CN114341682B

CN114341682B - Adhesive layer-containing polarizing film laminate, and optical display panel using same

Info

Publication number: CN114341682B
Application number: CN202080061044.9A
Authority: CN
Inventors: 木村智之; 小野宽大; 外山雄祐; 竹田哲郎; 高田胜则; 木村启介; 山下智弘; 杉野洋一郎
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2019-08-28
Filing date: 2020-08-20
Publication date: 2024-10-18
Anticipated expiration: 2040-08-20
Also published as: CN114341682A; TW202122839A; WO2021039583A1; KR20220049009A; JP2021033159A; JP7309521B2

Abstract

The present invention provides a polarizing film laminate and the like which can solve the problems of multiolefination, decoloration and heating redness in a lump. The polarizing film laminate is a polarizing film laminate comprising a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one surface of the polarizing film, wherein the adhesive layer comprises an adhesive polymer, and the adhesive polymer is copolymerized with an acid component in an amount of 5 wt.% or less in all monomer components constituting the adhesive polymer, wherein in an x-y orthogonal coordinate system in which the iodine concentration of the polarizing film is an x-axis and the moisture content of the polarizing film laminate is a y-axis, the polarizing film laminate comprises an iodine concentration and a moisture content contained in a region surrounded by a first coordinate point connecting the iodine concentration of 7.0wt.% and the moisture content of 0.7g/m ² and a second coordinate point connecting the iodine concentration of 2.2wt.% and the moisture content of 3.2g/m ², a second coordinate point connecting the iodine concentration of 2.2wt.% and the moisture content of 4.0g/m 3256, a fifth coordinate point connecting the iodine concentration of 3.0 g/m and the moisture content of 3.2g/m 37, and a fifth coordinate point connecting the iodine concentration of 3.2 wt.% and the moisture content of 3.2g/m 37, and a fifth coordinate point connecting the iodine concentration of 3.2g/m 3, and a fifth coordinate point connecting the iodine concentration of the moisture content of 3.2g/m and the moisture content of 3.2g/m 3 g/m.2 g/3.

Description

Adhesive layer-containing polarizing film laminate, and optical display panel using same

Technical Field

The present invention relates to a polarizing film laminate with an adhesive layer and an optical display panel using the same.

Background

In recent years, optical display panels such as liquid crystal panels and organic EL panels have found various possibilities for use in power running vehicles such as automobiles, electric trains, and airplanes, in addition to use in electric appliances such as smart phones, personal computers, and IoT home appliances. For example, it is conceivable to mount an optical display panel on a windshield, an instrument panel, an exterior package, or other various body parts of an automobile, thereby providing various information to a driver and transmitting the various information to the outside.

However, unlike smart phones and the like, in many cases, power running vehicles are used in severe outdoor environments, and the performance of an optical display panel, particularly a polarizing film laminate (polarizing plate) for the optical display panel, and a polarizing film (polarizing mirror) for the polarizing film laminate is deteriorated due to a use environment such as high temperature or high humidity, and in the worst case, may even be unusable.

Patent document 1 discloses an example of a polarizer having improved durability in a high-temperature or high-humidity environment, a polarizing plate using the polarizer, and a liquid crystal display device using the polarizing plate. As durability, among them, red leakage (elimination of polarization of long wavelength light) under crossed nicols occurring when placed under high temperature conditions is regarded as a problem point, and in order to solve this problem, it has been proposed to contain zinc and adjust the relationship between the zinc content and the iodine content to a given range.

Similarly, patent document 2 relates to a polarizing plate for an image display device for vehicle use, which has improved durability in a high-temperature or high-humidity environment, wherein attention is paid to the moisture content of the polarizing plate and the saturated water absorption amount of the protective film. In order to solve this problem, patent document 2 proposes to use a transparent protective film having a saturated water absorption in a predetermined range as a transparent protective film to be bonded to a polarizer and to reduce the amount of moisture in the polarizer, while requiring high-temperature durability in a vehicle-mounted polarizer, which may cause a significant decrease in transmittance of the polarizer due to a high-temperature environment.

Patent document 3 also relates to a polarizing plate having improved durability at high temperature or high humidity, wherein attention is paid to the moisture content of the polarizing plate and the moisture permeability of the protective film. Since the inside of a polarizing plate is in a high-temperature and high-humidity state in a high-temperature environment, and as a result, the change in light transmittance, polarization degree, hue of an image, and the like becomes large, and reliability as a polarizing plate becomes low, there has been proposed a method of bonding a protective film having low moisture permeability in a state where the moisture content of a polarizing plate is reduced as much as possible.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2003-29042

Patent document 2: japanese patent laid-open publication No. 2014-102353

Patent document 3: japanese patent laid-open No. 2002-90546

Disclosure of Invention

Problems to be solved by the invention

As problems that occur in high-temperature or high-humidity environments, there are known "multi-olefination", "decoloration" and "thermal erythro", as to an optical display panel, particularly a polarizing film laminate for an optical display panel, and a polarizing film for a polarizing film laminate.

In general, "multiolefination" refers to a phenomenon in which the monomer transmittance of a polarizing film laminate is lowered by being placed in a high temperature or high humidity environment, and "discoloration" and "hot redness" are also known as a phenomenon in which the transmittance of a polarizing film is raised and the polarizing film is colored red by being placed in a high temperature or high humidity environment, when the orthogonal transmittance of wavelengths 410nm and 700nm is measured by disposing the polarizing film laminate so as to be orthogonal to each other, wherein "discoloration" is known as a phenomenon in which the transmittance of a long wavelength side of about 700nm and a short wavelength side of about 410nm is raised and discoloration occurs in black display, and "hot redness" is known as a phenomenon in which the transmittance of a long wavelength side of about 700nm is raised and the polarizing film is colored red.

Patent document 1 mainly focuses on the problem of "discoloration", patent document 2 mainly focuses on the problem of "polyalkylene", and patent document 3 mainly focuses on the problem of "heating red discoloration", and it is considered that the solutions proposed in the respective documents are effective at least in solving the respective problems. However, the inventions described in the respective patent documents are not necessarily sufficient to solve these problems in a lump.

The applicant of the present application repeatedly conducted intensive studies based on the fact that each of "polyethylenization", "decoloring" and "heating erythro-change" is related to each other by iodine and moisture, and further by temperature and humidity affecting moisture, and as a result, the following findings were obtained: these problems can be collectively solved by adjusting the iodine concentration of the polarizing film and the moisture content of the polarizing film laminate.

The present invention aims to solve the above 3 problems in total by adjusting the iodine concentration of the polarizing film and the moisture content of the polarizing film laminate.

In attaching the polarizing film to a liquid crystal cell or the like, an adhesive is generally used. In addition, since there are advantages in that the polarizing film can be instantaneously fixed to the liquid crystal cell or the like, and a drying process for adhering the polarizing film to the liquid crystal cell or the like is not required, the adhesive is often provided on one side of the polarizing film in the form of an adhesive layer in advance. That is, in lamination of the polarizer, a polarizer with an adhesive layer is generally used.

The characteristics required for the adhesive layer include: the adhesiveness is not reduced with time, and the durability is high; when the polarizing film is attached to the liquid crystal cell, even if the attachment position is wrong or a foreign matter is embedded in the attachment surface, the polarizing film can be peeled off from the surface of the liquid crystal panel and attached again (reworkability) or the like.

In the case of using the optical display panel for a power running vehicle, high temperature durability is also required for an adhesive for bonding a polarizing film constituting the optical display panel to a liquid crystal cell or the like. In such applications, as the adhesive composition constituting the adhesive, an adhesive composition containing an acid component such as acrylic acid in the monomer component of the adhesive polymer can be suitably used.

The present inventors have found that a novel problem of deterioration of the polyene due to the acid component copolymerized in the binder polymer occurs. In the above-described prior art, although researches on the polyethylenization of a polarizing film have been carried out, the durability and reworkability of an adhesive layer have not been studied, and no disclosure has been made about the problem.

The purpose of the present invention is to obtain a pressure-sensitive adhesive layer-equipped polarizing plate in which a pressure-sensitive adhesive layer is provided directly on a polarizing film or via an optically transparent polarizing film protective film, and which has excellent reliability and adhesion durability of optical characteristics and reworkability.

Means for solving the problems

The present inventors have focused on the influence of an acid component in a monomer component of a binder polymer contained in a binder layer on the performance of a polarizing film, and have completed the present invention. In the prior art, regarding the adhesive polymer contained in the adhesive layer, no study has been made from the viewpoint of the correlation between the ratio of the acid component in the monomer component and the performance of the adhesive layer-attached polarizing film laminate such as reliability of optical characteristics, adhesion durability, reworkability, and the like. The present inventors have found the amount of the acid component in the total monomer components of the adhesive polymer required for obtaining the adhesive layer-attached polarizing film laminate having excellent characteristics.

While not being bound by any theory, it is believed that if a substance containing an acid component such as acrylic acid is used as the monomer component of the binder polymer, the acid component acts as a catalyst for dehydration condensation of a polyvinyl alcohol (PVA) -based resin film constituting the polarizing film to promote the polyalkylation, although the high temperature durability is improved due to the action of hydrogen bonds of COOH groups of the acid component.

In order to solve the above problems, a polarizing film laminate according to one embodiment of the present invention is a polarizing film laminate comprising a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one side of the polarizing film,

The adhesive layer contains an adhesive polymer copolymerized with an acid component in an amount of 5 wt% or less of all monomer components constituting the adhesive polymer,

In an x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is the x-axis and the moisture content (g/m ²) of the polarizing film laminate is the y-axis, the polarizing film laminate has an iodine concentration and a moisture content contained in a region surrounded by a first line connecting a first coordinate point having an iodine concentration of 7.0wt.% and a moisture content of 0.7g/m ² and a second coordinate point having an iodine concentration of 2.2wt.% and a moisture content of 3.2g/m ², a second line connecting the second coordinate point and a third coordinate point having an iodine concentration of 2.2wt.% and a moisture content of 4.0g/m ², a third line connecting the third coordinate point and a fourth coordinate point having an iodine concentration of 3.0wt.% and a moisture content of 4.0g/m ², a fourth coordinate point connecting the fourth coordinate point having an iodine concentration of 10.0wt.% and a moisture content of 0.7g/m ², and the fifth coordinate point connecting the fifth coordinate point.

According to the polarizing film laminate with an adhesive layer of this embodiment, the problems of "polyethylenization", "decoloration", "heat discoloration", "adhesion durability" and "reworkability" can be collectively solved.

In the polarizing film laminate of the embodiment, the binder polymer may have a polydispersity (weight average molecular weight (Mw)/number average molecular weight (Mn)) of 3.0 or less. This is also true in (another) other embodiment of the present invention.

In the polarizing film laminate of the above embodiment, the thickness of the polarizing film may be 4 to 20 μm.

In addition, the polarizing film laminate according to another embodiment of the present invention is a polarizing film laminate with an adhesive layer, which comprises a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided on at least one surface of the polarizing film directly or via an optically transparent polarizing film protective film,

In an x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is taken as the x-axis and the moisture content (g/m ²) of the polarizing film laminate is taken as the y-axis, the polarizing film laminate has an iodine concentration and a moisture content contained in a region surrounded by a sixth line segment connecting the sixth coordinate point having an iodine concentration of 4.5wt.% and a moisture content of 2.0g/m ² and the second coordinate point having an iodine concentration of 2.2 g/m ², a second line segment connecting the second coordinate point and the third coordinate point having an iodine concentration of 2.2wt.% and a moisture content of 4.0g/m ², a third line segment connecting the third coordinate point and the fourth coordinate point having an iodine concentration of 3.0wt.% and a moisture content of 4.0g/m ², a seventh line segment connecting the fourth coordinate point having an iodine concentration of 4.5wt.% and a moisture content of 3.3g/m ², and the eighth line segment connecting the seventh coordinate point and the eighth line segment.

In the polarizing film laminate of the above embodiment, it may be: the sixth coordinate point is a coordinate point having an iodine concentration of 4.0wt.% and a moisture content of 2.3g/m ², and the seventh coordinate point is a coordinate point having an iodine concentration of 4.0wt.% and a moisture content of 3.5g/m ².

In the polarizing film laminate of the above embodiment, the thickness of the polarizing film may be 11 to 20 μm.

In another embodiment of the present invention, a polarizing film laminate is provided with a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one side of the polarizing film,

In an x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is taken as the x-axis and the moisture content (g/m ²) of the polarizing film laminate is taken as the y-axis, the polarizing film laminate has an iodine concentration and a moisture content contained in a region surrounded by a first coordinate point connecting the iodine concentration of 7.0wt.% and the moisture content of 0.7g/m ² and an eleventh line segment connecting the eighth coordinate point and the eighth coordinate point of the moisture content of 2.6g/m ², a tenth line segment connecting the eighth coordinate point and the ninth coordinate point of the iodine concentration of 6.0wt.% and the moisture content of 2.6g/m ², a twelfth line segment connecting the ninth coordinate point and the fifth coordinate point of the iodine concentration of 10.0wt.% and the moisture content of 0.7g/m ², and a fifth line segment connecting the first coordinate point and the fifth coordinate point.

In the polarizing film laminate of the above embodiment, it may be: the eighth coordinate point is a sixth coordinate point having an iodine concentration of 4.5wt.% and a moisture content of 2.0g/m ², and the ninth coordinate point is a tenth coordinate point having an iodine concentration of 7.2wt.% and a moisture content of 2.0g/m ².

In the polarizing film laminate of the above embodiment, the thickness of the polarizing film may be 4 to 11 μm.

In the polarizing film laminate of the above embodiment, the polarizing film preferably contains zinc.

Further, in the polarizing film laminate of the above embodiment, it is preferable that the transmittance of the monomer after heating at 95 ℃/500 hours is the same as or greater than the transmittance of the monomer before heating for a sample including the polarizing film laminate and glass plates laminated on both sides of the polarizing film laminate via an adhesive.

Thus, the problem of multiolefination can be effectively solved.

In the polarizing film laminate of the above embodiment, it is preferable that the amount of change in the orthogonal transmittance at a wavelength of 410nm by a heat treatment at 95 ℃/500 hours is less than 1% and the amount of change in the orthogonal transmittance at a wavelength of 700nm is less than 5% for a sample including the polarizing film laminate and glass plates laminated on both sides of the polarizing film laminate via an adhesive.

Thus, the problem of discoloration can be effectively solved.

In the polarizing film laminate of the above embodiment, it is preferable that the amount of change in the orthogonal transmittance at the wavelength of 410nm by the heat treatment at 95 ℃/500 hours is 1% or more and the amount of change in the orthogonal transmittance at the wavelength of 700nm is less than 5% for the sample including the polarizing film laminate and the glass plates laminated on both sides of the polarizing film laminate via the adhesive.

Thus, the problem of heating reddening can be effectively solved.

In the polarizing film laminate of the above embodiment, an antireflection layer may be provided on the surface of the visible side of the polarizing film with a base material interposed therebetween, and the antireflection film including the base material and the antireflection layer may have a moisture permeability of 15g/m ² ·24h or more.

In addition, the polarizing film laminate of the above embodiment preferably includes:

a liquid crystal cell including a liquid crystal layer including liquid crystal molecules aligned in one direction in a plane in a state where an electric field is not applied;

A first polarizing film disposed on one side of the liquid crystal cell; and

A second polarizing film disposed on the other side of the liquid crystal cell so that an absorption axis of the second polarizing film is orthogonal to an absorption axis of the first polarizing film,

A first retardation layer and a second retardation layer are disposed between the first polarizing film and the liquid crystal cell in this order from one side of the first polarizing film, wherein when the refractive index in the slow axis x direction in the plane of the first retardation layer is nx1, the refractive index in the fast axis direction is ny1, and the refractive index in the thickness z direction is nz1, the first retardation layer satisfies the relationship of nx1 > ny1 > nz1, and the second retardation layer satisfies the relationship of nz2 > nx2 > ny2 when the refractive index in the slow axis x direction in the plane of the second retardation layer is nx2, the refractive index in the fast axis direction is ny2, and the refractive index in the thickness z direction is nz 2.

A first polarizing film disposed on one side of the liquid crystal cell; and

A first retardation layer and a second retardation layer are disposed in this order from one side of the first polarizing film between the first polarizing film and the liquid crystal cell, and when the refractive index in the slow axis x direction in the plane of the first retardation layer is nx1, the refractive index in the fast axis direction is ny1, and the refractive index in the thickness z direction is nz1, the first retardation layer satisfies the relationship of nz1 > nx 1=ny1, and when the refractive index in the slow axis x direction in the plane of the second retardation layer is nx2, the refractive index in the fast axis direction is ny2, and the refractive index in the thickness z direction is nz2, the second retardation layer satisfies the relationship of nx2 > ny 2=nz2.

Further, the polarizing film laminate according to the above embodiment preferably includes:

a liquid crystal cell including a liquid crystal layer including liquid crystal molecules aligned in one direction in a plane in a state where an electric field is not applied; and

A polarizing film disposed on one side of the liquid crystal cell,

A retardation layer is disposed between the polarizing film and the liquid crystal cell, and satisfies a relationship of nx > nz > ny when a refractive index in a slow axis x direction in a plane of the retardation layer is nx, a refractive index in a fast axis direction is ny, and a refractive index in a thickness z direction is nz.

Further, in order to solve the above-described problems, an optical display panel according to an embodiment of the present invention includes: an optical display unit, the polarizing film laminate of any one of the above described above bonded directly to one surface of the optical display unit or via another optical film, and an optically transparent cover plate disposed on the opposite side of the optical display unit along the polarizing film laminate, wherein the optical display unit, the polarizing film laminate, and the transparent cover plate are bonded together by a transparent adhesive layer filled between them in a state of no void.

In the optical display panel of the above embodiment, the transparent cover plate may have a function of a capacitive touch sensor.

In the optical display panel according to the above embodiment, an ITO layer, which is a constituent element of the capacitive touch sensor, may be provided between the transparent cover plate and the polarizing film laminate.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the problems of "polyene", "decolor", "heat red change", "adhesion durability" and "reworkability" can be collectively solved.

Drawings

Fig. 1 is a schematic view showing a layer structure of an optical display panel.

Fig. 2 is a diagram illustrating an example of a method for producing a polarizing film.

Fig. 3 is a graph showing a calibration curve for calculating the iodine concentration of the polarizing film.

Fig. 4 is a diagram showing a structure for reliability test.

Fig. 5 is a graph obtained by plotting the results of examples and comparative examples.

Symbol description

1. Optical display panel

10. Optical display unit

11. Transparent adhesive

12. Polarizing film laminate

13. Transparent adhesive

14. Transparent cover plate

120. Polarizing film

121. Polarizing film protective film

122. Polarizing film protective film

Detailed Description

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. For convenience of explanation, only the preferred embodiment is shown, but the present invention is of course not limited thereto.

The present invention is directed to an optical display panel, particularly an optical display panel mounted on a vehicle body of an automobile, an electric car, an airplane, or other power running vehicles running by power, and a polarizing film laminate used for the optical display panel. Here, "attached to the vehicle body" does not necessarily mean the case where the optical display panel and the polarizing film laminate are fixed to the vehicle body, but includes the case where they are freely mounted on and carried into a power running vehicle, for example, as in the case of an optical display panel and a polarizing film laminate used for a smart phone or the like. In other words, "mounted to a vehicle body" includes all conditions in which the optical display panel, the polarizing film laminate, and the power running vehicle are used together, and are likely to be exposed to a high-temperature or high-humidity environment.

1. Optical display panel

Fig. 1 schematically illustrates an example of a layer structure of an optical display panel 1. The optical display panel 1 includes at least: the optical display unit 10, a polarizing film laminate 12 laminated on one surface 10a side (visible side) of the optical display unit 10, and an optically transparent cover plate 14 arranged on the opposite side, i.e., visible side, of the optical display unit 10 along the polarizing film laminate 12. On the other surface 10b side of the optical display unit 10, another polarizing film laminate 17 is disposed via a transparent adhesive 16. The optical display unit 10, the polarizing film laminate 12, and the cover plate 14 are bonded together by the layers of the transparent adhesives 11, 13 filled therebetween in a state of no void. In this specification, unless otherwise specified, the term "adhesion" includes adhesion (pressure-sensitive adhesion). The optical display unit 10 and the polarizing film laminate 12 may be directly bonded together by the transparent adhesive 11, but may be bonded together with other optical films (not shown) such as a retardation film and a viewing angle compensation film interposed therebetween as needed.

1-1. Optical display Unit

Examples of the optical display unit 10 include a liquid crystal unit and an organic EL unit.

As the organic EL unit, an organic EL unit in which a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially stacked on a transparent substrate to form a light-emitting body (organic electroluminescent light-emitting body) or the like can be suitably used. The organic light emitting layer is a laminate of various organic thin films, and various layer structures may be employed, including, for example: a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer made of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer, or the like.

As the liquid crystal cell, any of a reflective liquid crystal cell using external light, a transmissive liquid crystal cell using light from a light source such as the backlight 18, and a semi-transmissive and semi-reflective liquid crystal cell using both light from the outside and light from the light source can be used. In the case where the liquid crystal cell is a liquid crystal cell that uses light from a light source, as shown in fig. 1, a polarizing film laminate 17 may be disposed on the opposite side of the optical display unit (liquid crystal cell) 10 from the viewing side, and a light source 18 such as a backlight may be disposed. The light source-side polarizing film laminate 17 and the liquid crystal cell 10 are bonded together with a layer of a suitable transparent adhesive 17 interposed therebetween. As a driving method of the liquid crystal cell, any type of method such as VA mode, IPS mode, TN mode, STN mode, bend (band) alignment (pi type) can be used.

1-2 Cover plate

Examples of the cover plate 14 include a transparent plate (window layer) and a touch panel. As the transparent plate, a transparent plate having suitable mechanical strength and thickness can be used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, a glass plate, or the like can be used. The surface of the cover plate 14 may be subjected to a low reflection treatment using, for example, a low reflection film (not shown). As the touch panel, various touch panels such as a resistive film type, a capacitive type, an optical type, and an ultrasonic type, a glass plate having a touch sensor function, a transparent resin plate, and the like can be used.

In the case of using a capacitive touch panel as the cover plate 14, a front transparent plate made of glass or a transparent resin plate is preferably provided on the side closer to the visible side than the touch panel. In this case, the transparent adhesive 13 bonded between the cover plate 14 and the polarizing film laminate 12 is provided as an ITO layer (not shown) which is a constituent element of the capacitive touch sensor.

[ Adhesive composition ]

An adhesive composition that can be used for the transparent adhesive 11 and the like will be described.

< Adhesive Polymer >)

The binder polymer to be contained in the binder composition is not particularly limited as long as it is a polymer having adhesiveness which is usually used as a base polymer of the binder, and a polymer having Tg of 0 ℃ or less (usually-100 ℃ or more) is preferable for the reason that balance of the adhesive properties is easily obtained. Among these binder polymers, polyester-based polymers, (meth) acrylic polymers and the like can be suitably used.

The binder polymer used in the present invention is copolymerized with an acid component.

As the polyester-based polymer, a saturated polyester or a copolyester of a polyhydric alcohol and a polycarboxylic acid is generally used.

Examples of the polyol include: diols such as ethylene glycol, propylene glycol, hexamethylenediol, neopentyl glycol, 1, 2-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, decamethylenediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.

Examples of the polycarboxylic acid include: aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2, 5-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, 1, 4-naphthalene dicarboxylic acid, 1, 5-naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylsulfone carboxylic acid, and anthracene dicarboxylic acid; alicyclic dicarboxylic acids such as1, 3-cyclopentanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, 3-diethylsuccinic acid, glutaric acid, 2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecanedicarboxylic acid, and the like. As the polycarboxylic acid, 2 or more kinds of polycarboxylic acids, for example, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are often used in combination.

In the present invention, by containing such an acid component in the binder polymer, the durability of the binder is improved, and the occurrence of foaming, peeling, and the like can be prevented for a long period of time. The upper limit value of the amount of the acid component is less than 5% by weight, preferably less than 3% by weight, and more preferably less than 2% by weight, based on the amount of the entire monomer components constituting the binder polymer. If the amount of the acid component exceeds the upper limit value, the polarization film is adversely affected and reworkability of the adhesive layer tends to be lowered. The lower limit value of the amount of the acid component is preferably 0.01% by weight or more, more preferably 0.2% by weight or more, and still more preferably 0.5% by weight or more, based on the amount of the entire monomer components constituting the binder polymer. If the amount of the acid component is small, the durability of the adhesive layer tends to be lowered.

The polyhydric alcohol and the polycarboxylic acid used for the polyester polymer are not particularly limited, and various polyhydric alcohols and polycarboxylic acids can be used, and as the polyhydric alcohol, polymer polyols such as polycarbonate diol can be used. The polyester-based polymer can be obtained by mixing the above diol component with a 3-or more-membered polyol and/or a 3-or more-membered polycarboxylic acid. The weight average molecular weight of the polyester-based polymer is usually 1.1 ten thousand or more.

The (meth) acrylic polymer generally contains an alkyl (meth) acrylate as a monomer unit as a main component. The term (meth) acrylate refers to an acrylate and/or a methacrylate.

As the alkyl (meth) acrylate constituting the main skeleton of the (meth) acrylic polymer, there may be exemplified alkyl (meth) acrylates having a linear or branched alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isotetradecyl, undecyl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. These alkyl (meth) acrylates may be used alone or in combination. The average number of carbon atoms of these alkyl groups is preferably 3 to 9.

Further, an aromatic ring-containing alkyl (meth) acrylate such as phenoxyethyl (meth) acrylate and benzyl (meth) acrylate may be used. The aromatic ring-containing alkyl (meth) acrylate may be used by mixing a polymer obtained by polymerizing the aromatic ring-containing alkyl (meth) acrylate with the above-mentioned exemplary (meth) acrylic polymer, but from the viewpoint of transparency, the aromatic ring-containing alkyl (meth) acrylate is preferably used by copolymerizing with the above-mentioned alkyl (meth) acrylate.

For the purpose of improving the adhesion and heat resistance, 1 or more kinds of comonomers having a polymerizable functional group containing an unsaturated double bond such as a (meth) acryloyl group or vinyl group may be introduced into the (meth) acrylic polymer by copolymerization. Specific examples of such comonomers include, for example: hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and 4-hydroxymethylcyclohexyl (meth) acrylate; carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloxynaphthalene sulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

Among the above comonomers, as the acid component in the present invention, a comonomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group is exemplified. Specific examples of the comonomer used as the acid component include, for example: carboxyl group-containing monomers such as acrylic acid, (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, propyl (meth) acrylate sulfonate, and (meth) acryloxynaphthalene sulfonic acid; and phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

In the case where an acid component is present, from the viewpoint of adverse effects caused by the acid, it is considered that an acid of a system having relatively weak acidity such as a carboxyl group-containing monomer is preferable, and then a phosphoric acid group-containing monomer, a sulfonic acid group-containing monomer, or the like may be used.

Examples of the monomer used for the purpose of modification include: (N-substituted) amide monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylol propane (meth) acrylamide; alkyl aminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and the like; alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; succinimide-based monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryl-6-oxyhexamethylene succinimide, N- (meth) acryl-8-oxyoctamethylene succinimide, and N-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-dodecylmaleimide and N-phenylmaleimide; and (3) a itaconimide monomer such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide and N-dodecyl itaconimide.

Further, as the modifying monomer, it is also possible to use: vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methyl vinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyridine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylpyrazineVinyl monomers such as oxazole, vinyl morpholine, N-vinylcarboxylic acid amide, styrene, α -methylstyrene, N-vinylcaprolactam, etc.; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; polyethylene glycol acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine-containing (meth) acrylate, silicone (meth) acrylate, 2-methoxyethyl acrylate, and other acrylic monomers. Further, isoprene, butadiene, isobutylene, vinyl ether and the like are exemplified.

Further, as the copolymerizable monomer other than the above, a silane-based monomer containing a silicon atom and the like can be mentioned. Examples of the silane monomer include: 3-acryloxypropyl triethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyl trimethoxysilane, 4-vinylbutyl triethoxysilane, 8-vinyloctyl trimethoxysilane, 8-vinyloctyl triethoxysilane, 10-methacryloxydecyl trimethoxysilane, 10-acryloxydecyl trimethoxysilane, 10-methacryloxydecyl triethoxysilane, 10-acryloxydecyl triethoxysilane, and the like.

In addition, as the comonomer, it is possible to use: and (3) a multifunctional monomer having 2 or more unsaturated double bonds such as (meth) acryloyl groups and vinyl groups, such as an esterified product of (meth) acrylic acid and a polyhydric alcohol, such as tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, bisphenol a diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like, a polyester (meth) acrylate, an epoxy (meth) acrylate, a urethane (meth) acrylate, and the like, wherein 2 or more unsaturated double bonds such as (meth) acryloyl groups and vinyl groups are added to a skeleton of a polyester, an epoxy, a urethane, and the like, as the same functional groups as the monomer component.

Among these comonomers, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferably used from the viewpoints of adhesion and durability. The hydroxyl group-containing monomers and the carboxyl group-containing monomers may be used in combination. In the case where the adhesive composition contains a crosslinking agent, these comonomers become reaction sites with the crosslinking agent. Since the reactivity of the hydroxyl group-containing monomer, carboxyl group-containing monomer, and the like with the intermolecular crosslinking agent is sufficient, it is preferable to improve the cohesiveness and heat resistance of the resulting adhesive layer. The hydroxyl group-containing monomer is preferable from the viewpoint of reworkability, and the carboxyl group-containing monomer is preferable from the viewpoint of both durability and reworkability.

The hydroxyl group-containing monomer may be used in an amount of about 0.01 to 30% by weight, preferably about 0.03 to 20% by weight, and more preferably about 0.05 to 10% by weight, of the total monomer components constituting the binder polymer.

In addition to the above, the comonomer other than the acid component may be used in an amount of about 0 to 30% by weight, preferably about 0.1 to 20% by weight, and more preferably about 0.1 to 10% by weight, of all the monomer components constituting the binder polymer.

The weight average molecular weight (Mw) of the binder polymer used in the present invention is preferably 90 to 300 tens of thousands. The weight average molecular weight is more preferably 120 to 250 ten thousand in view of durability, particularly heat resistance. If the weight average molecular weight is less than 90 ten thousand, the polymer component having a low molecular weight increases, and the crosslinking density of the gel (adhesive layer) increases, and the adhesive layer becomes hard and the stress relaxation property is impaired. In addition, if the weight average molecular weight is more than 300 ten thousand, the viscosity increases, and gelation occurs during polymerization of the polymer, which is not preferable.

The binder polymer used in the present invention preferably has a polydispersity (weight average molecular weight (Mw)/number average molecular weight (Mn)) of 3.0 or less, more preferably 1.05 to 2.5, and still more preferably 1.05 to 2.0. When the polydispersity (Mw/Mn) exceeds 3.0, the polymer having a low molecular weight increases, and a large amount of the crosslinking agent is necessary to increase the gel fraction of the adhesive layer, and the remaining crosslinking agent reacts with the polymer having gelled, so that the crosslinking density of the gel (adhesive layer) increases, and the adhesive layer becomes hard and the stress relaxation property is impaired, which is not preferable. In addition, when the amount of the low molecular weight polymer is large and the amount of the uncrosslinked polymer or oligomer (sol portion) is large, the adhesive layer is broken due to the uncrosslinked polymer or the like segregated in the vicinity of the interface of the adhesive layer in contact with the adherend under heating/humidifying conditions or the like, which causes peeling of the adhesive layer. The weight average molecular weight and polydispersity (Mw/Mn) were determined from values calculated by GPC (gel permeation chromatography) and converted to polystyrene.

The binder polymer used in the present invention can be produced by appropriately selecting known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerization. The resulting binder polymer may be any copolymer such as a random copolymer, a block copolymer, or a graft copolymer.

In the solution polymerization, for example, ethyl acetate, toluene, or the like is used as a polymerization solvent. As a specific example of the solution polymerization, the reaction is carried out under a reaction condition in which a polymerization initiator is added under a flow of an inert gas such as nitrogen, usually at about 50 to 70℃for about 10 minutes to 30 hours. In particular, by shortening the polymerization time to about 30 minutes to 3 hours, the formation of low molecular weight oligomers formed in the latter stage of polymerization can be suppressed, and the polydispersity (Mw/Mn) can be adjusted to a preferable range of 3.0 or less.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization are not particularly limited, and may be suitably selected for use. The weight average molecular weight of the binder polymer may be controlled according to the amount of the polymerization initiator, the chain transfer agent, and the reaction conditions, and the amount of the binder polymer may be appropriately adjusted according to the type of the above-mentioned substances.

Examples of the polymerization initiator include: 2,2' -azobisisobutyronitrile, 2' -azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2' -azobis (2-methylpropionamidine) disulfate, 2' -azobis (N.N ' -dimethyleneisobutyramidine), 2' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate (manufactured by Wako pure chemical industries, ltd.), VA-057), persulfates such as potassium persulfate and ammonium persulfate, peroxide initiators such as bis (2-ethylhexyl) peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-N-octanoyl peroxide, 1, 3-tetramethylbutyl peroxy2-ethylhexanoate, bis (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1-di-t-hexylcyclohexane peroxide, t-butylhydroperoxide, hydrogen peroxide, redox initiators such as a combination of persulfate and sodium hydrogen sulfite, a combination of peroxide and sodium ascorbate, and the like, and a redox initiator such as a peroxide and a reducing agent.

The polymerization initiator may be used alone or in combination of 2 or more kinds, and the total content thereof is preferably about 0.005 to 1 part by weight, more preferably about 0.02 to 0.5 part by weight, based on 100 parts by weight of the monomer.

For example, in order to produce the (meth) acrylic polymer having the weight average molecular weight using 2,2' -azobisisobutyronitrile as a polymerization initiator, the amount of the polymerization initiator is preferably about 0.06 to 0.2 parts by weight, more preferably about 0.08 to 0.175 parts by weight, based on 100 parts by weight of the total monomer components.

Examples of the chain transfer agent include: dodecyl mercaptan, glycidyl mercaptan, thioglycollic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2, 3-dimercapto-1-propanol, and the like. The chain transfer agent may be used alone or in combination of 2 or more kinds, and the total content thereof is preferably about 0.1 part by weight or less relative to 100 parts by weight of the total amount of the monomer components.

Examples of the emulsifier used in the emulsion polymerization include: anionic emulsifiers such as sodium dodecyl sulfate, ammonium dodecyl sulfate, sodium dodecyl benzene sulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block polymer, and the like. These emulsifiers may be used alone or in combination of 2 or more.

Further, as the reactive emulsifier, specifically, examples of the emulsifier having a radical polymerizable functional group such as an acryl group or an allyl ether group introduced therein include: AQUALON HS-10, HS-20, KH-10, BC-05, BC-10, BC-20 (all of which are manufactured by first Industrial pharmaceutical Co., ltd.), ADEKA REASOAP SE N (manufactured by Asahi Denka Co., ltd.), etc. The reactive emulsifier enters the polymer chain after polymerization, and thus the water resistance is improved, which is preferable. The amount of the emulsifier to be used is preferably 0.3 to 5 parts by weight, more preferably 0.5 to 1 part by weight, in view of polymerization stability and mechanical stability, based on 100 parts by weight of the total amount of the monomer components.

The binder polymer used in the present invention is usually a binder polymer having a weight average molecular weight in the range of 30 to 400 tens of thousands. In view of durability, particularly heat resistance, it is preferable to use a binder polymer having a weight average molecular weight of 50 to 300 ten thousand. More preferably 65 to 200 tens of thousands. When the weight average molecular weight is less than 30 ten thousand, it is not preferable in view of heat resistance. In addition, when the weight average molecular weight is more than 400 ten thousand, it is not preferable in view of the adhesiveness and the adhesion. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated by polystyrene conversion.

< Other ingredients in adhesive composition >

In addition, the adhesive composition used in the present invention may contain a crosslinking agent. As the crosslinking agent, an organic crosslinking agent and a polyfunctional metal chelate can be used. Examples of the organic crosslinking agent include: isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, and the like. The polyfunctional metal chelate is a chelate obtained by covalently or coordinately bonding a polyvalent metal and an organic compound. As the polyvalent metal atom, al, cr, zr, co, cu, fe, ni, V, zn, in, ca, mg, mn, Y, ce, sr, ba, mo, la, sn, ti is exemplified. Examples of the atoms in the covalently or coordinately bonded organic compound include oxygen atoms, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

As the crosslinking agent, an isocyanate-based crosslinking agent and/or a peroxide-based crosslinking agent is preferable. Examples of the compound of the isocyanate-based crosslinking agent include: isocyanate monomers such as toluene diisocyanate, chlorophenylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate, isocyanate compounds obtained by adding these isocyanate monomers to trimethylolpropane or the like, isocyanurate compounds, biuret compounds, and urethane prepolymer-type isocyanates such as polyether polyols, polyester polyols, acrylic polyol esters, polybutadiene polyols, and polyisoprene polyols, which have undergone an addition reaction. Particularly preferred are polyisocyanate compounds such as polyisocyanate compounds selected from one of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate and isophorone diisocyanate or derived therefrom. Here, the polyisocyanate compound selected from one of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate and isophorone diisocyanate or derived therefrom includes hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, polyol-modified hexamethylene diisocyanate, polyol-modified hydrogenated xylylene diisocyanate, trimer-type hydrogenated xylylene diisocyanate, polyol-modified isophorone diisocyanate, and the like. The polyisocyanate compound exemplified is preferable because the reaction with hydroxyl groups proceeds rapidly by using, in particular, an acid or a base contained in the polymer as a catalyst, and thus, the crosslinking rate is particularly improved.

The peroxide-type crosslinking agent may be used as long as it is a peroxide that generates a radical active species by heating or light irradiation and crosslinks the base polymer of the adhesive composition, but in view of handleability and stability, it is preferable to use a peroxide having a half-life temperature of 80 to 160℃in 1 minute, and more preferable to use a peroxide having a half-life temperature of 90 to 140℃in 1 minute.

Examples of the peroxide that can be used as the crosslinking agent include: di (2-ethylhexyl) peroxydicarbonate (1-min half-life temperature: 90.6 ℃), di (4-t-butylcyclohexyl) peroxydicarbonate (1-min half-life temperature: 92.1 ℃), di (sec-butyl) peroxydicarbonate (1-min half-life temperature: 92.4 ℃), t-butyl peroxyneodecanoate (1-min half-life temperature: 103.5 ℃), t-hexyl peroxypivalate (1-min half-life temperature: 109.1 ℃), t-butyl peroxypivalate (1-min half-life temperature: 110.3 ℃), dilauroyl peroxide (1-min half-life temperature: 116.4 ℃), di (1-min half-life temperature: 117.4 ℃), di (1, 3-tetramethylbutyl) peroxy2-ethylhexanoate (1-min half-life temperature: 124.3 ℃), di (4-methylbenzoyl) peroxide (1-min half-life temperature: 128.2 ℃), t-butyl peroxyisobutyrate (1-min half-life temperature: 109.1-min half-life temperature: 1-life temperature: 136; 1-cyclohexane (1-t-life temperature: 149 ℃)). Among them, bis (4-t-butylcyclohexyl) peroxydicarbonate (1-minute half-life temperature: 92.1 ℃ C.), dilauryl peroxide (1-minute half-life temperature: 116.4 ℃ C.), dibenzoyl peroxide (1-minute half-life temperature: 130.0 ℃ C.), and the like are exemplified because of particularly excellent crosslinking reaction efficiency.

The half-life of the peroxide is an index indicating the decomposition rate of the peroxide, and means the time until the residual amount of the peroxide becomes half. The decomposition temperature at which the half-life is obtained at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer's catalogue, for example, in "organic peroxide catalogue 9 th edition (month 5 2003) of japan oil and fat corporation.

The amount of the crosslinking agent to be used is preferably 0.01 to 20 parts by weight, more preferably 0.03 to 10 parts by weight, based on 100 parts by weight of the binder polymer. If the crosslinking agent is less than 0.01 parts by weight, the cohesive force of the adhesive tends to be insufficient, and foaming may occur during heating, whereas if it is more than 20 parts by weight, the moisture resistance is insufficient, and peeling is likely to occur in a reliability test or the like.

The isocyanate-based crosslinking agent may be used alone or in combination of 1 or 2 or more, and is preferably contained in an amount of 0.01 to 2 parts by weight, more preferably 0.02 to 2 parts by weight, and still more preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight of the binder polymer. The resin composition may be appropriately contained in consideration of the cohesive force, prevention of peeling in the durability test, and the like.

The peroxide may be used alone or in combination of 1 or 2 or more, and the total amount thereof is 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the adhesive polymer. In order to adjust the processability, reworkability, crosslinking stability, peelability, etc., it may be appropriately selected within this range.

The method for measuring the peroxide decomposition amount remaining after the reaction treatment may be, for example, a method by HPLC (high performance liquid chromatography).

More specifically, for example, about 0.2g of the adhesive composition after the reaction treatment may be taken out each time, immersed in 10ml of ethyl acetate, shaken at 120rpm for 3 hours at 25℃by a shaker, extracted, and then allowed to stand at room temperature for 3 days. Next, 10ml of acetonitrile was added, and the mixture was shaken at 120rpm for 30 minutes at 25℃and about 10. Mu.l of an extract obtained by filtration through a membrane filter (0.45 μm) was injected into HPLC, and analyzed as the peroxide amount after the reaction treatment.

As the additive, a silane coupling agent is particularly preferably blended. As the silane coupling agent, there may be mentioned: silicon compounds having an epoxy structure such as 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; amino-containing silicon compounds such as 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) 3-aminopropyl trimethoxysilane and N- (2-aminoethyl) 3-aminopropyl methyldimethoxysilane; 3-chloropropyl trimethoxysilane; (meth) acryl-containing silane coupling agents such as acetoacetyl trimethoxysilane, 3-acryloyloxy propyl trimethoxysilane, and 3-methacryloyloxy propyl triethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyl triethoxysilane. In particular, 3-glycidoxypropyl trimethoxysilane and acetoacetyl-containing trimethoxysilane are preferably used because they can be effectively inhibited. The silane coupling agent can impart durability, particularly an effect of suppressing peeling in a humidified environment. The silane coupling agent is used in an amount of 1 part by weight or less, further 0.01 to 1 part by weight, preferably 0.02 to 0.6 part by weight, based on 100 parts by weight of the binder polymer. If the amount of the silane coupling agent is increased, the adhesion to the liquid crystal cell may be excessively increased, which may affect the reworkability or the like.

The adhesive composition used in the present invention may contain other known additives, and for example, powder such as a colorant and a pigment, a dye, a surfactant, a plasticizer, a tackifier, a surface lubricant, a leveling agent, a softener, an antioxidant, an anti-aging agent, a light stabilizer, an ultraviolet absorber, a polymerization inhibitor, an inorganic or organic filler, metal powder, granules, a foil, and the like may be added to the adhesive composition as appropriate according to the use. In addition, within a controllable range, redox species added with a reducing agent may be used.

When forming the pressure-sensitive adhesive layer from the pressure-sensitive adhesive composition, it is preferable to adjust the amount of the crosslinking agent added in the whole amount and sufficiently consider the influence of the crosslinking treatment temperature and the crosslinking treatment time.

The crosslinking treatment temperature and the crosslinking treatment time can be adjusted according to the crosslinking agent used. The crosslinking treatment temperature is preferably 170℃or less.

The crosslinking treatment may be performed at a temperature at the time of the drying step of the pressure-sensitive adhesive layer, or may be performed by providing a separate crosslinking treatment step after the drying step.

The crosslinking treatment time may be set in consideration of productivity and handleability, but is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

[ Adhesive layer ]

The adhesive layer will be described.

The polarizing film laminate with an adhesive layer of the present invention is provided with an adhesive layer directly on at least one surface of a polarizing film or via an optically transparent polarizing film protective film.

As a method for forming the adhesive layer, for example, there can be mentioned: a method in which the pressure-sensitive adhesive composition is applied to a separator or the like subjected to a peeling treatment, and after drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition is transferred to an optical film; or a method of forming an adhesive layer on an optical film by applying the adhesive composition to an optical film, and drying and removing a polymerization solvent. In the case of applying the adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

As the separator subjected to the release treatment, a silicone release liner can be preferably used. In the step of forming the adhesive layer by applying the adhesive composition to such a liner and drying it, a suitable method can be appropriately used as a method for drying the adhesive according to the purpose. The coating film is preferably dried by heating. The heating and drying temperature is preferably 40 to 200 ℃, more preferably 50 to 180 ℃, particularly preferably 70 to 170 ℃. By setting the heating temperature in the above range, an adhesive layer having excellent adhesive properties can be obtained.

The drying time may be appropriately used for a suitable time. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

The adhesive layer may be formed on the surface of the polarizing film, or may be formed after various easy-to-adhere treatments such as corona treatment and plasma treatment. In addition, the surface of the pressure-sensitive adhesive layer may be subjected to an easy-to-adhere treatment.

When an adhesive layer is provided on the surface of the polarizing film, it is desirable to use an acid-free system for the adhesion promoting layer and the adhesive layer.

As a specific method for forming the adhesion-promoting layer, there are the following methods: and a method in which a solution containing a urethane polymer (Denatron B-C, manufactured by Nagase ChemteX Co., ltd.) is adjusted to a solid content of 0.2% by weight with a water/isopropyl alcohol (65:35 by volume ratio) mixed solution, and the adjusted solution is applied to a polarizing plate using a Meyer rod #5 and dried at 50℃for 30 seconds to form an adhesive coating layer having a thickness of 25 nm.

As a method for forming the adhesive layer, various methods can be employed. Specific examples include: roll coating, roll licking coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, die lip coating, extrusion coating using a die coater, and the like.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 500. Mu.m. Preferably 1 to 250. Mu.m, more preferably 1 to 100. Mu.m, still more preferably 1 to 35. Mu.m.

By reducing the thickness of the adhesive layer, the effect on the polyalkylene of the adhesive layer-attached polarizing film laminate can be reduced with respect to the total amount of acid in the adhesive of the polarizing film.

In addition, in general, if the thickness of the adhesive layer is reduced, the adhesive force is reduced, and the shrinkage stress of the polarizing plate due to shrinkage of the polarizing film tends to reduce the adhesion durability such as warpage and peeling under high temperature and high humidity, so that it is not preferable to reduce the thickness of the adhesive layer. However, by thinning the polarizing film, the shrinkage stress of the polarizing plate can be reduced, and as a result, even if the thickness of the adhesive layer is thinned, the adhesion durability can be maintained or improved.

In the case where the adhesive layer is exposed, the adhesive layer may be protected with a sheet (separator) subjected to a peeling treatment until it is put to practical use.

Examples of the constituent material of the separator include: plastic films such as polyethylene, polypropylene, polyethylene terephthalate and polyester films, porous materials such as paper, cloth and nonwoven fabric, and suitable sheet materials such as nets, foam sheets, metal foils and laminates thereof, etc., but plastic films are preferably used in view of excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include: polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like.

The thickness of the separator is usually about 5 to 200. Mu.m, preferably about 5 to 100. Mu.m. The separator may be subjected to a release treatment, an anti-fouling treatment, or an antistatic treatment such as a coating treatment, a mixing treatment, or a vapor deposition treatment, with an organosilicon-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agent, or a silica powder, as necessary. In particular, the separator can be further improved in releasability from the pressure-sensitive adhesive layer by suitably subjecting the surface of the separator to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment.

The release-treated sheet used in the production of the pressure-sensitive adhesive layer-attached polarizing film laminate can be used as a separator for the pressure-sensitive adhesive layer-attached polarizing film laminate, and thus the process can be simplified.

2. Polarizing film laminate

Polarizing film laminate 12 includes at least: a polarizing film 120, and a polarizing film protective film 121 bonded to at least one surface of the polarizing film 120, for example, the visible side. As in the present embodiment, the polarizing film protective films 121 and 122 may be bonded to both surfaces of the polarizing film 120, that is, both the visible side and the opposite side of the polarizing film 120, via an appropriate adhesive (not shown). Although not particularly shown, another optical film may be provided between the polarizing film 120 and the polarizing film protective films 121 and 122.

In order to solve the problems occurring in a high-temperature or high-humidity environment, particularly the problems of "multi-olefination", "decoloration" and "heating redness", the present invention focuses attention on the iodine concentration (wt.%) of the polarizing film 120 and the moisture content (g/m ²) of the polarizing film laminate 12. These values can be adjusted, for example, at the time of manufacturing the polarizing film or at the time of manufacturing the polarizing film laminate.

2-1 Polarizing film

The polarizing film 120 is made of a polyvinyl alcohol (PVA) -based resin film containing iodine. As a material of the PVA-based film applicable to the polarizing film, PVA or a derivative thereof can be used. Examples of the derivative of PVA include, in addition to polyvinyl formal and polyvinyl acetal, derivatives modified with an olefin such as ethylene and propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid and crotonic acid, an alkyl ester thereof, and acrylamide. PVA having a polymerization degree of about 1000 to 10000 and a saponification degree of about 80 to 100 mol% is usually used. PVA-based films made of these materials tend to contain moisture easily.

The PVA-based film may contain an additive such as a plasticizer. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include: glycerol, diglycerol, triglycerol, ethylene glycol, propylene glycol, polyethylene glycol, and the like. The amount of plasticizer is not particularly limited, but is preferably 20% by weight or less in the PVA-based film.

2-1-1. Production of polarizing film

In the case of producing a polarizing film having a film thickness of 6 μm or more, for example, a dyeing treatment for dyeing the PVA-based film with iodine and a stretching treatment for stretching the PVA-based film in at least one direction are performed. In general, the PVA-based film may be subjected to a series of treatments including swelling, dyeing, crosslinking, stretching, washing with water, and drying.

The swelling treatment may be performed by, for example, immersing the PVA-based film in a swelling bath (water bath). By this treatment, dirt and an anti-blocking agent on the surface of the PVA film can be washed and the PVA film can be swelled, whereby unevenness such as uneven dyeing can be prevented. Glycerin, potassium iodide, and the like may be suitably added to the swelling bath. The temperature of the swelling bath is, for example, about 20 to 60 ℃, and the immersion time in the swelling bath is, for example, about 0.1 to 10 minutes.

The dyeing treatment may be performed, for example, by immersing the PVA-based film in an iodine solution. The iodine solution is usually an aqueous iodine solution and contains potassium iodide as an iodine and dissolution aid. The iodine concentration is, for example, about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The potassium iodide concentration is, for example, about 0.01 to 10% by weight, preferably 0.02 to 8% by weight.

In the dyeing treatment, the temperature of the iodine solution is, for example, about 20 to 50 ℃, preferably 25 to 40 ℃. The dipping time is, for example, about 10 to 300 seconds, preferably 20 to 240 seconds. In the iodine dyeing treatment, the concentration of the iodine solution, the immersion temperature of the PVA film in the iodine solution, the immersion time, and other conditions are adjusted so that the iodine content and the potassium content in the PVA film fall within the above-described ranges.

The crosslinking treatment may be performed, for example, by immersing the PVA-based film dyed with iodine in a treatment bath containing a crosslinking agent. As the crosslinking agent, any suitable crosslinking agent may be used. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, glutaraldehyde, and the like. These crosslinking agents may be used alone or in combination. The solvent of the solution for the crosslinking bath is usually water, but an organic solvent having compatibility with water may be appropriately added. The crosslinking agent is used in a proportion of, for example, 1 to 10 parts by weight relative to 100 parts by weight of the solvent. Preferably, the solution of the crosslinking bath further contains an auxiliary agent such as iodide. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. The temperature of the crosslinking bath is, for example, about 20 to 70℃and preferably 40 to 60 ℃. The immersion time in the crosslinking bath is, for example, about 1 second to 15 minutes, preferably about 5 seconds to 10 minutes.

The stretching treatment is a treatment of stretching the PVA-based film in at least one direction. Generally, a PVA-based film is uniaxially stretched in a transport direction (longitudinal direction). The stretching method is not particularly limited, and any of a wet stretching method and a dry stretching method may be employed. In the case of using the wet stretching method, the PVA-based film is stretched to a given magnification in a treatment bath. As the solution of the stretching bath, a solution obtained by adding a compound necessary for various treatments to a solvent such as water or an organic solvent (e.g., ethanol) can be suitably used. Examples of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In the production of the polarizing film, the stretching treatment may be performed at any stage. Specifically, the swelling, dyeing, and crosslinking may be performed simultaneously, or at any time before and after each treatment. In addition, the stretching may be performed in a plurality of stages. The cumulative stretch ratio of the PVA-based film is, for example, 5 times or more, preferably about 5 to 7 times.

The PVA-based film (stretched film) after each treatment is subjected to a water washing treatment and a drying treatment according to a conventional method.

The water-washing treatment can be performed, for example, by immersing the PVA-based film in a water-washing bath. The water bath may be pure water or an aqueous solution of iodide (e.g., potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably 0.1 to 10% by weight. Adjuvants such as zinc sulfate and zinc chloride can also be added into the iodide water solution.

The water washing temperature is, for example, in the range of 5 to 50 ℃, preferably 10 to 45 ℃, and more preferably 15 to 40 ℃. The dipping time is, for example, about 10 to 300 seconds, preferably 20 to 240 seconds. The water washing treatment may be performed only 1 time, or may be performed as many times as necessary. When the water washing treatment is performed a plurality of times, the types and concentrations of additives contained in the water bath used for each treatment can be appropriately adjusted.

The drying treatment of the PVA-based film may be performed by any suitable method (e.g., natural drying, air drying, heat drying).

2-1-2. Manufacture of polarizing film

The polarizing film having a film thickness of less than 6 μm can be produced by the production method disclosed in japanese patent No. 4751481, for example. The manufacturing method comprises the following steps: a laminate preparation process of forming a PVA-based resin layer on a thermoplastic substrate; stretching the PVA-based resin layer integrally with the thermoplastic resin substrate; dyeing treatment for adsorbing the dichroic substance to the PVA resin layer, and the like. The PVA-based resin layer may be subjected to insolubilization treatment, crosslinking treatment, drying treatment, washing treatment, and the like, as needed. The stretching treatment may be performed before or after the dyeing treatment. Any stretching method may be used in stretching in a gaseous atmosphere or in stretching in an aqueous solution such as an aqueous boric acid solution. The stretching may be one-stage stretching or multi-stage stretching of 2 or more stages.

An example of a method for producing a polarizing film will be described with reference to fig. 2. Here, a PVA-based resin layer formed on a resin base material is integrally stretched with the resin base material, thereby producing a polarizing film.

[ Laminate production Process (A) ]

First, an amorphous ester-based thermoplastic resin substrate having a glass transition temperature of 75 ℃, which has a thickness of 200 μm, for example, isophthalic acid copolymerized polyethylene terephthalate (hereinafter referred to as "amorphous PET") 6 in which isophthalic acid is copolymerized, and a 4 to 5 wt% concentration aqueous PVA solution obtained by dissolving a PVA powder having a polymerization degree of 1000 or more and a saponification degree of 99% or more in water are prepared. Next, in the laminate manufacturing apparatus 20 including the coating means 21, the drying means 22, and the surface modification treatment means 23, the aqueous PVA solution was coated on the amorphous PET substrate 6, and dried at a temperature of 50 to 60 ℃, and the PVA layer 2 having a thickness of 7 μm and having a glass transition temperature of 80 ℃ was formed on the PET substrate 6. Thus, laminate 7 including a 7 μm-thick PVA layer was produced. At this time, by corona-treating the surface of the amorphous PET substrate 6 by the surface modification treatment device 23, the adhesion between the amorphous PET substrate 6 and the PVA layer 2 formed thereon can be improved.

Next, the laminate 7 including the PVA layer was subjected to the following 2-stage stretching treatment of auxiliary stretching in an atmosphere including gas and stretching in an aqueous boric acid solution, to finally produce a polarizing film having a thickness of 3 μm.

[ Auxiliary stretching treatment in gas atmosphere (B) ]

In the auxiliary stretching treatment (B) in the gas atmosphere of the first stage, the laminate 7 including the PVA layer 2 having a thickness of 7 μm was stretched integrally with the PET base material 6, to produce a "stretched laminate 8" including the PVA layer 2 having a thickness of 5 μm. Specifically, in the auxiliary stretching apparatus 30 in a gas atmosphere in which the stretching means 31 is provided in the oven 33, the stretching means 31 of the oven 33 set to a stretching temperature environment of 130 ℃ is provided with the laminate 7 including the PVA layer 2 having a thickness of 7 μm, and free-end unidirectional stretching is performed so that the stretching ratio becomes 1.8 times, to thereby produce the stretched laminate 8. In this stage, the roll 8' of the stretched laminate 8 can be manufactured by the winding device 32 provided together with the oven 30.

[ Dyeing treatment (C) ]

Next, by the dyeing treatment (C), a colored laminate 9 was produced in which iodine in a dichroic substance was adsorbed to the PVA layer 2 having a thickness of 5 μm in which PVA molecules were aligned. Specifically, in the dyeing apparatus 40 including the dyeing bath 42 of the dyeing liquid 41, the stretched laminate 8 is continuously discharged from the continuous discharge device 43 provided together with the roll 8' attached to the dyeing apparatus 40, immersed in the dyeing liquid 41 containing iodine and potassium iodide at a liquid temperature of 30 ℃ for an arbitrary period of time, and the transmittance of the monomer constituting the PVA layer of the finally produced polarizing film is set to 40 to 44%, whereby the colored laminate 9 obtained by adsorbing iodine to the PVA layer 2 after the orientation of the stretched laminate 8 is produced.

In this treatment, since the PVA layer 2 contained in the stretched laminate 8 is not dissolved in the dyeing liquid 41, water is used as a solvent, and the iodine concentration is set to 0.30 wt%. The concentration of potassium iodide in the dye solution 41 for dissolving iodine in water was set to 2.1 wt%. The ratio of iodine to potassium iodide concentration was 1 to 7. More specifically, the stretched laminate 8 was immersed in a dyeing liquid 41 having an iodine concentration of 0.30 wt% and a potassium iodide concentration of 2.1 wt% for 60 seconds, to thereby produce a colored laminate 9 in which iodine was adsorbed to the PVA layer 2 having a thickness of 5 μm after the PVA molecules were oriented.

[ Stretching treatment in aqueous boric acid solution (D) ]

The colored laminate 9 including the iodine-oriented PVA layer 2 was further stretched by the stretching treatment in the aqueous boric acid solution of the second stage to produce an optical film laminate 60 including a 3 μm-thick constituent polarizing film and an iodine-oriented PVA layer. Specifically, in the in-boric acid stretching apparatus 50 including the boric acid bath 52 of the boric acid aqueous solution 51 and the stretching mechanism 53, the colored laminate 9 continuously discharged from the dyeing apparatus 40 is immersed in the boric acid aqueous solution 51 containing boric acid and potassium iodide and set to a stretching temperature environment of 65 ℃ in liquid temperature, and then the stretching mechanism 53 provided in the in-boric acid stretching apparatus 50 performs free-end unidirectional stretching so that the stretching ratio becomes 3.3 times, thereby producing the optical film laminate 60 including the PVA layer having a thickness of 3 μm.

[ Cleaning treatment (G) ]

Next, the optical film laminate 60 including the polarizing film is preferably directly sent to the cleaning process (G). The purpose of the cleaning process (G) is to wash away unwanted residues adhering to the surface of the polarizing film by the cleaning liquid 81 of the cleaning device 80. The cleaning process (G) may be omitted, and the taken out optical film laminate 60 including the polarizing film may be directly subjected to the drying process (H).

[ Drying treatment (H) ]

The optical film laminate 60 after cleaning is sent to a drying process (H), and is dried here. Next, the dried optical film laminate 60 is wound into a continuous web of the optical film laminate 60 by a winding device 91 provided together with the drying device 90, and a roll of the optical film laminate 60 including a polarizing film is produced. As the drying treatment (H), any suitable method may be used, such as natural drying, air drying, and heat drying. For example, in the drying device 90 of the oven, drying is performed for 240 seconds by hot air at 60 ℃.

2-1-3 Others

The polarizing film preferably contains zinc. By containing zinc in the polarizing film, the decrease in transmittance and the deterioration in hue of the polarizing film laminate after the heat test tend to be suppressed. When the polarizing film contains zinc, the zinc content in the polarizing film is preferably 0.002 to 2 wt%, more preferably 0.01 to 1 wt%.

Preferably, the polarizing film further contains sulfuric acid ions. By containing sulfuric acid ions in the polarizing film, the transmittance of the polarizing film laminate after the heating test tends to be suppressed from decreasing. When the polarizing film contains sulfate ions, the content of sulfate ions in the polarizing film is preferably 0.02 to 0.45 wt%, more preferably 0.05 to 0.35 wt%, and still more preferably 0.1 to 0.25 wt%. The content of sulfuric acid ions in the polarizing film can be calculated from the sulfur atom content.

In order to contain zinc in the polarizing film, it is preferable to perform zinc impregnation treatment in the manufacturing process of the polarizing film. In order to contain sulfuric acid ions in the polarizing film, it is preferable to perform sulfuric acid ion treatment in the process of producing the polarizing film.

The zinc impregnation treatment may be performed, for example, by immersing the PVA-based film in a zinc salt solution. The zinc salt is preferably an inorganic chlorine compound of an aqueous solution of zinc halide such as zinc chloride and zinc iodide, zinc sulfate, zinc acetate, or the like. In addition, various zinc complexes may be used in the zinc impregnation treatment. In addition, when an aqueous solution containing potassium ions and iodide ions by potassium iodide or the like is used as the zinc salt solution, zinc ions are easily impregnated, which is preferable. The concentration of potassium iodide in the zinc salt solution is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight.

The sulfuric acid ion treatment can be performed, for example, by immersing the PVA-based film in an aqueous solution containing a metal sulfate. As the metal sulfate, the following metal sulfate is preferable: the metal sulfate is easily separated into sulfate ions and metal ions in the treatment liquid, and the metal sulfate is easily introduced into the PVA-based film in an ionic state. For example, alkali metals such as sodium and potassium are examples of the metal species forming the metal sulfate; alkaline earth metals such as magnesium and calcium; cobalt, nickel, zinc, chromium, aluminum, copper, manganese, iron, and the like.

In the production of the polarizing film, the zinc impregnation treatment and the sulfuric acid ion treatment may be performed at any stage. That is, the zinc impregnation treatment and the sulfuric acid ion treatment may be performed before the dyeing treatment or after the dyeing treatment. The zinc impregnation treatment and the sulfuric acid ion treatment may be performed simultaneously. Preferably, zinc sulfate is used as the zinc salt and the metal sulfate, and the PVA-based film is immersed in a treatment bath containing zinc sulfate, thereby simultaneously performing zinc impregnation treatment and sulfuric acid ion treatment. The zinc salt and the metal sulfate may be co-present in the dyeing solution in advance, and the zinc impregnation treatment and/or the sulfuric acid ion treatment may be performed simultaneously with the dyeing treatment. The zinc impregnation treatment and the sulfuric acid ion treatment may be performed simultaneously with the stretching.

2-2 Polarizing film protective film

Examples of the material constituting the polarizing film protective films 121 and 122 include thermoplastic resins excellent in transparency, mechanical strength, and thermal stability. Specific examples of such thermoplastic resins include cellulose-based resins such as cellulose triacetate, polyester-based resins, polyether sulfone-based resins, polysulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth) acrylic resins, cyclic polyolefin-based resins (norbornene-based resins), polyarylate-based resins, polystyrene-based resins, PVA-based resins, and mixtures thereof.

The polarizing film protective film may be a film having a function of a retardation film at the same time.

The thickness of the polarizing film protective film may be appropriately adjusted for the purpose of adjusting the moisture content of the polarizing film laminate. From the viewpoints of workability such as strength and handling properties, and thin layer properties, it is preferably about 1 to 500. Mu.m, more preferably 2 to 300. Mu.m, and still more preferably 5 to 200. Mu.m.

The polarizing film protective film may contain 1 or more kinds of optional additives. Examples of the additive include: ultraviolet light absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

2-3 Other optical films

The polarizing film and the polarizing film protective film may be directly bonded, but may be laminated with other optical films. The other optical film is not particularly limited, and for example, a retardation film, a viewing angle compensation film, and the like can be used. The retardation film as the other optical film may be a film having a function as a protective film.

As described above, the polarizing film protective film may also have the function of a phase difference film, but in this case, a phase difference film that is another optical film may be omitted. On the other hand, in the case where the polarizing film protective film also has the function of a phase difference film, the phase difference film may be provided as another optical film. In this case, the retardation film substantially includes 2 or more layers.

2-4 Adhesive

For example, a radical polymerization curable adhesive, a cationic polymerization curable adhesive, or an aqueous adhesive may be used for bonding the polarizing film 120 and the polarizing film protective films 121 and 122, or bonding other optical films such as a retardation film and the like.

(Radical polymerization curable adhesive)

The radical polymerization curable adhesive contains a radical polymerizable compound as a curable compound. The radical polymerizable compound may be a compound that is cured by active energy rays, or may be a compound that is cured by heat. Examples of the active energy ray include: electron beam, ultraviolet, visible, etc.

Examples of the radical polymerizable compound include: a compound having a radically polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. As the radical polymerizable compound, a polyfunctional radical polymerizable compound is preferably used. The radical polymerizable compound may be used alone or in combination of 1 or more than 2. In addition, a multifunctional radical polymerizable compound and a monofunctional radical polymerizable compound may be used in combination.

The polymerizable compound is preferably a compound having a high logP value (octanol/water partition coefficient), and the radical polymerizable compound is also preferably a compound having a high logP value. Here, the log P value is an index characterizing the lipophilicity of a substance, and represents the logarithmic value of the partition coefficient of octanol/water. A high log p value means lipophilicity, i.e. low water absorption. The log P value may be measured (flask permeation method described in JIS-Z-7260) or calculated based on the structure of each compound as a constituent component (curable component or the like) of the curable adhesive (ChemDraw Ultra manufactured by Cambridge Soft Co.).

The log p value of the radical polymerizable compound is preferably 2 or more, more preferably 3 or more, particularly preferably 4 or more. If the amount is within this range, deterioration due to moisture of the polarizer can be prevented, and a polarizing film excellent in durability at high temperature and high humidity can be obtained.

Examples of the polyfunctional radical polymerizable compound include: tripropylene glycol di (meth) Acrylate, tetraethylene glycol di (meth) Acrylate, 1, 6-hexanediol di (meth) Acrylate, 1, 9-nonanediol di (meth) Acrylate, 1, 10-decanediol di (meth) Acrylate, 2-ethyl-2-butylpropanediol di (meth) Acrylate, bisphenol A ethylene oxide adduct di (meth) Acrylate, bisphenol A propylene oxide adduct di (meth) Acrylate, bisphenol A diglycidyl ether di (meth) Acrylate, neopentyl glycol di (meth) Acrylate, tricyclodecanedimethanol di (meth) Acrylate, cyclic trimethylolpropane methylal (meth) Acrylate (Cyclic Trimethylolpropane formal (meth) Acrylate), dimeth (meth) AcrylateEsters of (meth) acrylates such as alkylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and EO-modified diglycerol tetra (meth) acrylate with polyhydric alcohols; 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene; epoxy (meth) acrylates; urethane (meth) acrylates; polyester (meth) acrylates, and the like.

Among the above-mentioned polyfunctional radically polymerizable compounds, polyfunctional radically polymerizable compounds having a high log P value are preferable. Examples of such a compound include: alicyclic (meth) acrylates such as tricyclodecane dimethanol di (meth) acrylate (logp=3.05) and isobornyl (meth) acrylate (logp=3.27); equal length chain aliphatic (meth) acrylates of 1, 9-nonanediol di (meth) acrylate (logp=3.68), 1, 10-decanediol diacrylate (logp=4.10); multi-branched (meth) acrylates such as hydroxypivalic acid neopentyl glycol (meth) acrylate adduct (logp=3.35) and 2-ethyl-2-butylpropanediol di (meth) acrylate (logp=3.92); aromatic ring-containing (meth) acrylates such as bisphenol a di (meth) acrylate (logp=5.46), bisphenol a ethylene oxide 4 molar adduct di (meth) acrylate (logp=5.15), bisphenol a propylene oxide 2 molar adduct di (meth) acrylate (logp=6.10), bisphenol a propylene oxide 4 molar adduct di (meth) acrylate (logp=6.43), 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene (logp=7.48), and p-phenylphenol (meth) acrylate (logp=3.98).

When the polyfunctional radical polymerizable compound and the monofunctional radical polymerizable compound are used in combination, the content of the polyfunctional radical polymerizable compound is preferably 20 to 97% by weight, more preferably 50 to 95% by weight, still more preferably 75 to 92% by weight, and particularly preferably 80 to 92% by weight, based on the total amount of the radical polymerizable compounds. When the content is within this range, a polarizing film excellent in durability under high temperature and high humidity conditions can be obtained.

Examples of the monofunctional radically polymerizable compound include (meth) acrylamide derivatives having a (meth) acrylamide group. When the (meth) acrylamide derivative is used, an adhesive layer excellent in adhesion can be formed with high productivity. Specific examples of the (meth) acrylamide derivative include, for example: n-alkyl (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; n-hydroxyalkyl (meth) acrylamide derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propane (meth) acrylamide; n-aminoalkyl-containing (meth) acrylamide derivatives such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; n-alkoxy (meth) acrylamide derivatives such as N-methoxymethacrylamide and N-ethoxymethacrylamide; and N-mercaptoalkyl (meth) acrylamide derivatives such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide. As the heterocyclic ring-containing (meth) acrylamide derivative in which a nitrogen atom of a (meth) acrylamide group forms a heterocyclic ring, for example, there can be used: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among these, N-hydroxyalkyl (meth) acrylamide-containing derivatives are preferred, and N-hydroxyethyl (meth) acrylamide is more preferred.

As the monofunctional radical polymerizable compound, a (meth) acrylic acid derivative having a (meth) acryloyloxy group can be used; carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid; lactam vinyl monomers such as N-vinyl pyrrolidone, N-vinyl-epsilon-caprolactam, methyl vinyl pyrrolidone, and the like; vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinylAnd vinyl monomers having nitrogen-containing heterocyclic rings such as oxazole and vinyl morpholine.

In the case of using the multifunctional radical polymerizable compound and the monofunctional radical polymerizable compound in combination, the content of the monofunctional radical polymerizable compound is preferably 3 to 80% by weight, more preferably 5 to 50% by weight, still more preferably 8 to 25% by weight, and particularly preferably 8 to 20% by weight, relative to the total amount of the radical polymerizable compounds. When the content is within this range, a polarizing film excellent in durability under high temperature and high humidity conditions can be obtained.

The radical polymerization curable adhesive may further contain other additives. In the case where the radical polymerization curable adhesive contains a curable compound that is cured by active energy rays, the adhesive may further contain, for example: photopolymerization initiator, photoacid generator, silane coupling agent, etc. In addition, in the case where the radical polymerization curable adhesive contains a curable compound by heat curing, the adhesive may further contain a thermal polymerization initiator, a silane coupling agent, or the like. Further, examples of other additives include: polymerization inhibitor, polymerization initiator, leveling agent, wettability modifier, surfactant, plasticizer, ultraviolet absorber, inorganic filler, pigment, dye, etc.

(Cationic polymerization curable adhesive)

The cationically polymerizable curable adhesive contains a cationically polymerizable compound as a curable compound. Examples of the cationically polymerizable compound include compounds having an epoxy group and/or an oxetane group. The compound having an epoxy group is preferably a compound having at least 2 epoxy groups in the molecule. Examples of the compound having an epoxy group include: a compound having at least 2 epoxy groups and at least 1 aromatic ring (aromatic epoxy compound), a compound having at least 2 epoxy groups in the molecule and at least 1 of them being formed between adjacent 2 carbon atoms constituting an alicyclic ring (alicyclic epoxy compound), and the like.

Preferably, the cationic polymerization curable adhesive contains a photo-cationic polymerization initiator. The photo cation polymerization initiator generates cation species or lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., thereby initiating polymerization of epoxy groups and oxetane groups. In addition, the cationically polymerizable curable adhesive may further contain the above-mentioned additives.

(Aqueous adhesive)

As the aqueous adhesive, for example, it is preferable to use: an aqueous solution (for example, a solid content concentration of 0.5 to 60% by weight) of an aqueous adhesive such as an isocyanate-based adhesive, a PVA-based adhesive, a gelatin-based adhesive, a vinyl-based latex or an aqueous polyester.

The adhesive may be applied to any one of the polarizing film 120, the polarizing film protective films 121 and 122, and other optical films, or to any two of them. In general, it is preferable that the polarizing film is immersed in an aqueous adhesive solution and then laminated with the polarizing film protective films 121 and 122 by a roll laminator or the like. The thickness of the adhesive layer is not particularly limited, and is, for example, about 30nm to 1000nm in terms of the thickness after drying.

The polarizing film, the polarizing film protective film, and other optical films are laminated with an adhesive, and the laminate is subjected to a drying treatment. In the drying step of the laminate, the purpose of the adhesive is to dry and solidify, and the purpose of the moisture content to improve the initial optical characteristics of the polarizing film laminate is to decrease. As a drying method, heat drying is generally used. The drying conditions are preferably in the range of 50 to 95℃and more preferably in the range of 60 to 85 ℃.

The drying condition of the laminate is not particularly limited, but in view of the efficiency and practicality of the treatment, the drying temperature is preferably 50 ℃ or higher, and from the viewpoint of making the optical properties of the polarizing film laminate uniform, it is preferably 95 ℃ or lower. The drying temperature may be increased stepwise in the above temperature range.

The laminate may be dried continuously with the bonding treatment of the polarizing film and the polarizing film protective film, and other optical films. Further, after the laminate of the polarizing film, the polarizing film protective film, and other optical films is temporarily wound into a roll, drying may be performed as another process.

In general, in order to reduce the moisture content of the polarizing film laminate, high-temperature/long-time drying conditions are necessary. Drying at high temperature/for a long time is preferable from the viewpoint of reduction in the moisture content of the polarizing film laminate, but on the other hand, there is a case where deterioration in optical characteristics and the like of the polarizing film laminate occurs. By using a polarizing film protective film having a small saturated water absorption amount and a polarizing film protective film having a high moisture permeability, the moisture content of the polarizing film laminate can be adjusted to the above-described desired range without using severe drying conditions.

2-5 Adhesive

The adhesive described in the above "1-3. Transparent adhesive" can be used in the same manner.

3. Reliability evaluation item

A number of phenomena that may occur in the polarizing film laminate, namely, multiolefination, discoloration, reddening by heating, adhesion durability, and reworkability were evaluated. The mechanism of each phenomenon is not clear, but it can be estimated as follows.

< Polyalkylene >

In a high-temperature and high-humidity environment, the single transmittance of the polarizing film laminate decreases. It is speculated that this decrease is due to the poly-olefination of PVA. Polyene means- (ch=ch) _n -, which can be formed in a polarizing film by heating. The polyene causes a significant decrease in transmittance of the polarizing film. In addition, in a high-temperature and high-humidity environment, the PVA-polyiodine complex is destroyed, and I ^- and I ₂ are easily produced.

The polyeneization of PVA is considered to be initiated by acceleration of dehydration reaction due to iodine (I ₂) generated in a high temperature and high humidity environment and heating, as shown in the following chemical formula 1.

(Chemical formula 1)

It is considered that the PVA-polyiodide complex present in the polarizing film is destroyed by heating, and thus I ₂ and OH groups in the PVA form a charge transfer complex (HO. I ₂), and then the polyolefination occurs via the OI group. When the acid component is contained in a large amount in the binder layer, it is considered that protons generated from the acid component act as a catalyst for the dehydration reaction of PVA, and thus, the polyalkylation is further promoted.

< Decoloring >

In the PVA-based film (polarizing film) dyed with iodine and stretched, iodine forms a complex (PVA multi-iodine complex) with the PVA in which the orientation has occurred in the form of multi-iodide ions of I ₃ ^- and I ₅ ^-. At this time, PVA forms crosslinking points by a crosslinking agent such as boric acid, thereby maintaining orientation.

However, if the polarizing film is exposed to high temperature and high humidity, hydrolysis of boric acid crosslinking is induced, resulting in a decrease in orientation of PVA, and disintegration of PVA multi-iodine complex occurs. Thus, the visible light absorption by the PVA polyiodine complex decreases, and the transmittance increases on the long wavelength side of about 700nm and on the short wavelength side of about 410 nm. Thus, discoloration in black display occurs in a polarizing film placed under high temperature and high humidity.

< Heating Red change >)

In the PVA-based film (polarizing film) dyed with iodine and stretched, iodine forms a complex with PVA in the form of polyiodide ions of I ₃ ^- and I ₅ ^- (PVA polyiodide complex). I ₃ ^- has a broad absorption peak around 470nm, and I ₅ ^- has a broad absorption peak around 600 nm. That is, the PVA-I ₃ ^- complex is responsible for the absorption on the short wavelength side (blue side) and the PVA-I ₅ ^- complex is responsible for the absorption on the long wavelength side (red side).

However, this PVA-I ₅ ^- complex is weak against heat, and if the polarizing film is exposed to high temperature, the complex formation of PVA and I ₅ ^- is broken, and I ₅ ^- is decomposed.

Therefore, in the polarizing film at high temperature, the PVA-I ₅ ^- complex responsible for absorption on the long wavelength side is reduced, and therefore, the transmittance on the long wavelength side of about 700nm is increased, and the polarizing film changes color to red.

Examples

4. Examples and comparative examples

The following description will be given of examples together with comparative examples, but it is needless to say that the present invention is not limited to the descriptions in these examples.

As examples and comparative examples, samples of various polarizing film laminates were prepared in which "film thickness of polarizing film (μm)", and/or "iodine concentration of polarizing film (wt.%)", and/or "moisture content of polarizing film laminate (g/m ²)".

Film thickness of polarizing film

The thickness (μm) of the polarizing film was measured using a spectrofilm thickness meter MCPD-1000 (manufactured by tsukamu electronics corporation). The thickness of the polarizing film protective film was also measured using the spectrofilm thickness meter. The polarizing film included in the sample may be taken out by immersing the sample in a solvent and dissolving the polarizing film protective film. As the solvent, for example, methylene chloride is used when the polarizing film protective film is a cellulose triacetate resin, cyclohexane is used when the polarizing film protective film is a cycloolefin resin, and methyl ethyl ketone is used when the polarizing film protective film is an acrylic resin, respectively. When the resin of the polarizing film protective film provided on one surface of the polarizing film is different from the resin of the polarizing film protective film provided on the other surface, the respective resins are sequentially dissolved using the above-described solvents.

< Iodine concentration of polarizing film >)

In the production of the polarizing film, the iodine concentration (wt.%) of the polarizing film may be changed by adjusting the concentration of the aqueous iodine solution used to impregnate the PVA-based film and the PVA layer, and the impregnation time.

The iodine concentration of the polarizing film was measured by the following method. The polarizing film included in the sample may be immersed in a solvent and the polarizing film protective film may be dissolved and taken out, similarly to the case of measuring the film thickness of the polarizing film.

(Fluorescent X-ray measurement)

In measuring the iodine concentration of the polarizing film, first, the iodine concentration was quantified by a calibration curve method of fluorescent X-ray analysis. The apparatus used was a fluorescence X-ray analyzer ZSX-PRIMUS IV (manufactured by Kyowa Co., ltd.).

The value directly obtained by the fluorescent X-ray analyzer is not the concentration of each element, but the fluorescent X-ray intensity (kcps) of the wavelength inherent to each element. Therefore, in order to determine the iodine concentration contained in the polarizing film, it is necessary to convert the fluorescent X-ray intensity into a concentration using a calibration curve. The iodine concentration of the polarizing film in the present specification and the like means an iodine concentration (wt%) based on the weight of the polarizing film.

(Preparation of calibration Curve)

The calibration curve was prepared as follows.

1. A known amount of potassium iodide was dissolved in an aqueous PVA solution to prepare 7 aqueous PVA solutions containing iodine at a known concentration. The PVA aqueous solution was applied to polyethylene terephthalate, dried, and peeled off to prepare samples 1 to 7 of PVA films containing iodine at a known concentration.

The iodine concentration (wt%) of the PVA film was calculated according to the following equation 1.

[ Mathematics 1]

Iodine concentration (wt%) = { amount of potassium iodide (g)/(amount of potassium iodide (g) +amount of PVA (g)) } × (127/166)

(Molecular weight of iodine: 127 molecular weight of potassium: 39)

2. The prepared PVA film was subjected to measurement of fluorescent X-ray intensity (kcps) corresponding to iodine by using a fluorescent X-ray analyzer ZSX-PRIMUS IV (manufactured by Kagaku Kogyo Co., ltd.). Wherein the fluorescence X-ray intensity (kcps) is set as the peak of the fluorescence X-ray spectrum. The thickness of the PVA film thus produced was measured using a spectroscope film thickness meter MCPD-1000 (manufactured by Katsukamu electronics Co., ltd.).

3. The fluorescent X-ray intensity (kcps/. Mu.m) per unit thickness of the film was obtained by dividing the fluorescent X-ray intensity by the thickness (μm) of the PVA film. The iodine concentration and the fluorescent X-ray intensity per unit thickness of each sample are shown in table 1.

TABLE 1

4. Based on the results shown in Table 1, a calibration curve was prepared with the X-ray intensity of fluorescence (kcps/. Mu.m) per unit thickness of the PVA film as the horizontal axis and the iodine concentration (wt%) contained in the PVA film as the vertical axis. The calibration curve produced is shown in fig. 3. The mathematical expression for determining the iodine concentration from the fluorescent X-ray intensity per unit thickness of the PVA film by passing through the calibration curve is determined as shown in mathematical expression 2. Note that R ² in fig. 3 is a correlation coefficient.

[ Math figure 2]

(Iodine concentration) (wt%) = 14.474 × (fluorescent X-ray intensity per unit thickness of PVA film) (kcps/. Mu.m)

(Calculation of iodine concentration)

The fluorescent X-ray intensity per unit thickness (kcps/. Mu.m) was determined by dividing the fluorescent X-ray intensity obtained by the sample measurement by the thickness. The intensity of fluorescent X-rays per unit thickness of each sample was substituted into equation 2 to determine the iodine concentration.

< Moisture content of polarizing film laminate >

The moisture content (g/m ²) of the polarizing film laminate can be determined mainly by adjusting the film thickness of the polarizing film, the material and thickness of the polarizing film protective film to be bonded to the polarizing film, and the like. The crosslinking treatment (boric acid content, etc.) in the production of the polarizing film may be adjusted.

The moisture content of the polarizing film laminate was measured by the following method.

First, the polarizing film laminates obtained in examples and comparative examples were cut into squares of 0.1m×0.1 m.

The cut sample was placed in a constant temperature and humidity apparatus and left in an environment with a temperature of 23℃and a relative humidity of 55% for 48 hours. Then, the sample was taken out in the same environment as in the constant temperature and humidity apparatus, i.e., in a clean room set at a temperature of 23 ℃ and a relative humidity of 55%, and the weight was measured within 5 minutes after taking out. The sample weight at this time was set to the initial weight W1 (g). It should be noted that, within about 15 minutes after removal, even if the temperature in the cleaning chamber varies by about 2 to 3 ℃, and even if the relative humidity in the cleaning chamber varies by about ±10%, the initial weight is not substantially affected.

Next, the taken sample was put into a desiccator and dried at 120 ℃ for 2 hours. Then, the dried sample was taken out in the above-mentioned clean room set at a temperature of 23 ℃ and a relative humidity of about 55%, and the weight was measured within 10 minutes after the taking out. The sample weight at this time was set to be the dried weight W2 (g). Unlike the above, the cooling time is not limited to 5 minutes but is limited to 10 minutes. In the same manner as described above, the weight after drying is not substantially affected as long as the time is less than about 15 minutes after removal.

From the initial weight W1 and the dried weight W2 of the sample thus obtained, the equilibrium moisture content M (g/M ²) of the polarizing film laminate was calculated by the following formula.

(Formula) m= (W1-W2)/(0.1×0.1)

The "moisture content of the polarizing film laminate" referred to in the present invention means the equilibrium moisture content calculated by the above-described method.

(Preparation of adhesive layer A)

First, 80.9 parts of butyl acrylate, 18 parts of benzyl acrylate, 1 part of acrylic acid, and 0.1 part of 4-hydroxybutyl acrylate were charged into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a condenser, to thereby obtain a monomer mixture. Further, 0.1 part of 2,2' -azobisisobutyronitrile as a polymerization initiator was added together with 100 parts of ethyl acetate with respect to 100 parts of the monomer mixture (solid content). While the mixture was slowly stirred, nitrogen gas was generally introduced into the flask to replace nitrogen. The polymerization was carried out for 8 hours while maintaining the liquid temperature in the flask at about 55 ℃, whereby a solution of an acrylic polymer having a weight average molecular weight (Mw) of 185 ten thousand and Mw/mn=3.8 was prepared.

Next, 0.45 parts of an isocyanate crosslinking agent (Coronate L, trimethylolpropane toluene diisocyanate, manufactured by Tosoh Co., ltd.), 0.1 parts of benzoyl peroxide (NYPER BMT, manufactured by Japanese fat & oil Co., ltd.) and 0.2 parts of gamma-glycidoxypropyl methoxysilane (KBM-403, manufactured by Xinyue chemical Co., ltd.) were further blended with 100 parts of the solid content of the acrylic polymer solution, thereby preparing a solution of the acrylic pressure-sensitive adhesive composition.

Next, the obtained solution was applied to one surface of a separator (MRF 38 manufactured by mitsubishi chemical polyester film co.). The separator is a polyethylene terephthalate film treated with an organosilicon based release agent. The obtained coating film was dried at 155 ℃ for 1 minute, thereby forming an adhesive layer a on the surface of the separator. The thickness of the adhesive layer was 20. Mu.m.

(Preparation of adhesive layer B)

First, 99 parts by weight of butyl acrylate (the same applies hereinafter), 1.0 part of 4-hydroxybutyl acrylate, and 0.3 part of 2,2' -azobisisobutyronitrile were charged together with 100 parts of ethyl acetate in a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a condenser. While the mixture was slowly stirred, nitrogen gas was introduced into the flask to replace nitrogen. The polymerization was carried out for 4 hours while maintaining the liquid temperature in the flask at about 55 ℃, whereby a solution of an acrylic polymer having a weight average molecular weight (Mw) of 165,000 and Mw/mn=3.7 was prepared.

Then, 0.3 parts of dibenzoyl peroxide (NYPER BMT, manufactured by Japanese fat & oil Co., ltd.) and 0.1 parts of trimethylolpropane xylylene diisocyanate (Sanjingku Kagaku Co., ltd.) were blended per 100 parts of the solid content of the acrylic polymer solution: TAKENATE D110N), 0.2 part of a silane coupling agent (manufactured by green chemical Co., ltd.): a-100, acetoacetyl-containing silane coupling agent), thereby preparing an adhesive composition.

Next, the obtained solution was applied to one surface of a separator (MRF 38 manufactured by mitsubishi chemical polyester film co.). The separator is a polyethylene terephthalate film treated with an organosilicon based release agent. The obtained coating film was dried at 155 ℃ for 1 minute, thereby forming an adhesive layer B on the surface of the separator. The thickness of the adhesive layer was 20. Mu.m.

(Preparation of adhesive layer C)

Adhesive layer C was produced in the same manner as adhesive layer a except that the polymerization time of the acrylic polymer was set to 2 hours in the production of adhesive layer a. The weight average molecular weight (Mw) of the acrylic polymer was 190 ten thousand, mw/mn=2.5.

(Preparation of adhesive layer D)

Adhesive layer D was produced in the same manner as adhesive layer a except that the composition of the acrylic polymer in the production of adhesive layer a was 80.9 parts of butyl acrylate, 18 parts of benzyl acrylate, 4.8 parts of acrylic acid, and 0.1 part of 4-hydroxybutyl acrylate. The weight average molecular weight (Mw) of the acrylic polymer was 210 ten thousand, mw/mn=4.0.

(Preparation of adhesive layer E)

First, 71.9 parts of butyl acrylate, 18 parts of benzyl acrylate, 10 parts of acrylic acid, and 0.1 part of 4-hydroxybutyl acrylate were charged into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a condenser, to thereby obtain a monomer mixture. Further, 0.1 part of 2,2' -azobisisobutyronitrile as a polymerization initiator was added together with 70 parts of ethyl acetate and 30 parts of toluene, relative to 100 parts of the monomer mixture (solid content). While the mixture was slowly stirred, nitrogen gas was introduced into the flask to replace nitrogen. The polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at about 55 ℃, whereby a solution of an acrylic polymer having a weight average molecular weight (Mw) of 80 ten thousand and Mw/mn=3.6 was prepared.

Next, a solution of an acrylic pressure-sensitive adhesive composition was prepared by mixing 100 parts of the solid content of the acrylic polymer solution with 1 part of an isocyanate crosslinking agent (Coronate L, trimethylolpropane toluene diisocyanate, manufactured by Tosoh Co., ltd.), 0.1 part of benzoyl peroxide (NYPER BMT, manufactured by Japanese fat & oil Co., ltd.) and 0.2 part of gamma-glycidoxypropyl methoxysilane (KBM-403, manufactured by Xinyue chemical Co., ltd.).

Next, the obtained solution was applied to one surface of a separator (MRF 38 manufactured by mitsubishi chemical polyester film co.). The separator is a polyethylene terephthalate film treated with an organosilicon based release agent. The obtained coating film was dried at 155 ℃ for 1 minute, thereby forming an adhesive layer E on the surface of the separator. The thickness of the adhesive layer was 20. Mu.m.

Example 1

(Production of polarizing film)

As the resin base material, an elongated amorphous isophthalic acid copolymerized polyethylene terephthalate film (degree of isophthalic acid based modification 5mol%, thickness: 100 μm) (degree of modification=ethylene isophthalate unit/(ethylene terephthalate unit+ethylene isophthalate unit)) was used. One surface of the resin substrate was subjected to corona treatment (treatment condition: 55 W.min/m ²), and an aqueous solution of 13 parts by weight of potassium iodide relative to PVA, which was prepared by mixing 90 parts by weight of PVA (polymerization degree 4200, saponification degree 99.2 mol%) and 10 parts by weight of acetoacetyl-modified PVA (trade name "GOHSEFIMER Z", manufactured by Nippon chemical Co., ltd.) was coated on the corona-treated surface at normal temperature. Then, the resultant was dried at 60℃to form a PVA based resin layer having a thickness of 13. Mu.m, thereby producing a laminate.

The resulting laminate was subjected to free-end unidirectional stretching to 2.4 times in the machine direction (longitudinal direction) in an oven at 130 ℃ between rolls having different peripheral speeds (auxiliary stretching in a gas atmosphere).

Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40 ℃ for 30 seconds (insolubilization treatment).

Next, in a dyeing bath (aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ℃, the solution was immersed for 60 seconds while adjusting the concentration so that the solution became a predetermined transmittance (dyeing treatment).

Then, the resultant solution was immersed in a crosslinking bath (an aqueous boric acid solution obtained by mixing 100 parts by weight of water with 3 parts by weight of potassium iodide and 5 parts by weight of boric acid) at a liquid temperature of 40℃for 30 seconds (crosslinking treatment).

Then, while immersing the laminate in an aqueous boric acid solution (boric acid concentration 3.0 wt%) at a liquid temperature of 70 ℃, unidirectional stretching (stretching in an aqueous solution) was performed between rolls having different peripheral speeds in the machine direction (longitudinal direction) so that the total stretching magnification became 5.5 times.

Then, the laminate was immersed in a washing bath (an aqueous solution obtained by mixing 100 parts by weight of water with 4 parts by weight of potassium iodide) at a liquid temperature of 20 ℃ (washing treatment).

Then, the metal roll was brought into contact with an SUS metal roll maintained at a surface temperature of 75 ℃ for 2 seconds or more while being dried (drying treatment) in an oven maintained at 90 ℃ (hot roll drying treatment).

Thus, a polarizing film having a thickness of 5.4 μm was obtained on the resin substrate.

(Production of polarizing film laminate)

Cycloolefin films (ZT 12, 18 μm, manufactured by Japanese rayleigh Co.) as protective films for polarizing films were bonded to the surfaces of the obtained polarizing films on the opposite sides from the resin base material by an ultraviolet-curable adhesive. Specifically, the curable adhesive described below was applied so that the total thickness of the curable adhesive became 1.0 μm, and was bonded by a roll machine. Then, UV light was irradiated from the cycloolefin film side to cure the adhesive. Next, the resin substrate was peeled off to obtain a polarizing film laminate including a cycloolefin polarizing film protective film and a polarizing film.

The details of the curable adhesive are as follows. An adhesive was prepared by mixing 40 parts by weight of N-hydroxyethyl acrylamide (HEAA), 60 parts by weight of Acryloylmorpholine (ACMO), and 3 parts by weight of a photoinitiator "IRGACURE 819" (manufactured by BASF corporation). The adhesive layer after curing was applied to the polarizing film so that the thickness of the adhesive layer became 1.0 μm, and the adhesive layer was cured by irradiation of ultraviolet rays as active energy rays. The ultraviolet irradiation used was a metal halide lamp in which gallium was enclosed, and an irradiation device: fusion UV Systems, LIGHT HAMMER manufactured by Inc, valve: v valve, peak illuminance: 1600mW/cm ² and cumulative exposure of 1000/mJ/cm ² (wavelength 380-440 nm), and the illuminance of ultraviolet light was measured by using a Sola-Check system manufactured by Solatell company.

(Removal of polarizing film)

The iodine concentration of the polarizing film was measured by taking out the polarizing film from the polarizing film laminate using cyclohexane as a solvent.

(Production of polarizing film laminate with adhesive layer)

The adhesive layer a was transferred onto one surface of the polarizing film laminate, thereby producing a polarizing film laminate with an adhesive layer of example 1.

Example 2

In the production of the polarizing film of example 1, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film. Other conditions were the same as in example 1.

Example 3

In the production of the polarizing film of example 1, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film. In addition, when the polarizing film laminate of example 1 was produced, cycloolefin films (ZF 12, 13 μm, manufactured by japan rayleigh corporation) were bonded as the polarizing film protective film. Other conditions were the same as in example 1.

Example 4

When the polarizing film laminate of example 1 was produced, a cellulose triacetate film-based film (TJ 40UL thickness 40 μm, manufactured by fuji film co.) was bonded as a polarizing film protective film. In addition, in the production of the polarizing film of example 1, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment. Other conditions were the same as in example 1.

Example 5

In the production of the polarizing film laminate of example 1, a transparent protective film (Ridong electric Co., ltd.) having a thickness of 40 μm and formed of a modified acrylic polymer having a lactone ring structure was bonded as the polarizing film protective film. In addition, in the production of the polarizing film of example 1, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment. Other conditions were the same as in example 1.

Example 6

(Production of polarizing film)

PVA films having an average polymerization degree of 2700 and a thickness of 30 μm were stretched while being dyed between rolls having different circumferential speed ratios. First, the PVA film was swollen by immersing it in a water bath at 30 ℃ for 1 minute, and after stretching it 1.2 times in the transport direction, it was immersed in an aqueous solution (liquid temperature 30 ℃) of potassium iodide (0.03 wt%) and iodine (0.3 wt%) for 1 minute, whereby it was stretched 3 times in the transport direction while dyeing it (unstretched film basis). Next, the stretched film was stretched to 6 times in the transport direction (unstretched film standard) while being immersed in an aqueous solution (bath) of boric acid (4 wt%), potassium iodide (5 wt%) and zinc sulfate (3.5 wt%) for 30 seconds. After stretching, drying was performed in an oven at 40℃for 3 minutes, to obtain a polarizing film of 12.0. Mu.m.

(Production of polarizing film laminate)

As the adhesive, an aqueous solution containing an acetoacetyl group-containing polyvinyl alcohol resin (average degree of polymerization 1200, degree of saponification 98.5 mol%, degree of acetoacetylation 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, a transparent protective film (ridong electric company) having a thickness of 20 μm formed of a modified acrylic polymer having a lactone ring structure was bonded to one surface of a polarizing film using a roll laminator at a temperature of 30 ℃, and a transparent protective film having a thickness of 27 μm formed of a hard coat layer (HC) having a thickness of 2 μm on a cellulose triacetate film (trade name "KC2UA" manufactured by konikama dada) having a thickness of 25 μm was bonded to the other surface, and then the resultant film was heated in an oven at 70 ℃ for 5 minutes to dry the film, thereby obtaining a polarizing film laminate having the transparent protective film bonded to both surfaces of the polarizing film.

The hard coat layer is formed by the following method. First, a hard coat layer forming material is prepared. The material was made as follows: to the resin solution (trade name "UNIDIC-806" manufactured by DIC corporation) obtained by dissolving an ultraviolet curable resin monomer or oligomer containing urethane acrylate as a main component in butyl acetate, 5 parts by weight of a photopolymerization initiator (product name "IRGACURE906" manufactured by BASF corporation) and 0.01 parts by weight of a leveling agent (product name "GRANDIC PC4100" manufactured by DIC corporation) were added per 100 parts by weight of the solid content in the solution, and cyclopentanone (hereinafter referred to as "CPN") and propylene glycol monomethyl ether (hereinafter referred to as "PGM") were added at a ratio of 45:55 so that the solid content concentration in the solution became 36% by weight, to thereby prepare a hard coat layer forming material. The hard coat layer-forming material thus prepared was applied to a transparent protective film so that the thickness of the cured hard coat layer became 2 μm, thereby forming a coating film. Then, the film was dried at 90℃for 1 minute, and then irradiated with ultraviolet rays having an accumulated light amount of 300mJ/cm ² by a high-pressure mercury lamp, and the film was subjected to a curing treatment.

(Removal of polarizing film)

The iodine concentration of the polarizing film was measured by taking out the polarizing film from the polarizing film laminate using methylene chloride and methyl ethyl ketone as solvents.

(Production of polarizing film laminate with adhesive layer)

The adhesive layer a was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing an adhesive layer-attached polarizing film laminate of example 6.

Example 7

In the production of the polarizing film of example 6, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time during the dyeing treatment. In addition, when the polarizing film laminate of example 6 was produced, a 30 μm thick transparent protective film (Ridong electric Co., ltd.) made of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the obtained polarizing film, and a 49 μm thick transparent protective film having a 9 μm thick HC formed on a 40 μm thick cellulose triacetate film (product name "KC4UY" manufactured by Konikoku Meida) was bonded to the other surface. Other conditions were the same as in example 6.

Example 8

A polarizing film laminate with an adhesive layer was produced in the same manner as in example 7 except that the adhesive layer C was transferred to one surface of the acrylic transparent protective film of the polarizing film laminate.

Example 9

In the production of the polarizing film of example 6, a PVA film having a thickness of 45 μm was stretched and transported in a stretching process to obtain a polarizing film having a thickness of 18.0 μm, and the concentration of iodine was changed by adjusting the concentration of the iodine aqueous solution and the immersion time in a dyeing process. In addition, when the polarizing film laminate of example 6 was produced, a transparent protective film (ridong electric company, TJ40UL thickness 40 μm) having a thickness of 30 μm formed of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the obtained polarizing film, and a cellulose triacetate film (fuji film company, TJ40UL thickness 40 μm) was bonded to the other surface. Other conditions were the same as in example 6.

EXAMPLE 10 to the upper portion example 13

In the production of the polarizing film of example 9, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film. Other conditions were the same as in example 9.

Example 14

A polarizing film laminate with an adhesive layer was produced in the same manner as in example 9 except that the adhesive layer C was transferred to one surface of the acrylic transparent protective film of the polarizing film laminate.

Example 15

A polarizing film laminate with an adhesive layer was produced in the same manner as in example 9 except that the adhesive layer D was transferred to one surface of the acrylic transparent protective film of the polarizing film laminate.

Comparative example 1 to the outside comparative example 2

In the production of the polarizing film of example 1, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film.

Further, the adhesive layer B was transferred onto one surface of the polarizing film laminate, thereby producing the polarizing film laminate with adhesive layer of comparative examples 1 and 2. Other conditions were the same as in example 1.

Comparative example 3 over-extension comparative example 4

In the production of the polarizing film of example 6, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film.

Further, the adhesive layer B was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing the polarizing film laminate with adhesive layer of comparative examples 3 and 4. Other conditions were the same as in example 6.

Comparative example 5

In the production of the polarizing film of example 7, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film.

Further, the adhesive layer B was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing an adhesive layer-attached polarizing film laminate of comparative example 5. Other conditions were the same as in example 7.

Comparative example 6

In the production of the polarizing film of example 9, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film.

Further, the adhesive layer B was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing an adhesive layer-attached polarizing film laminate of comparative example 6. Other conditions were the same as in example 9.

Comparative example 7

(Production of polarizing film)

In the production of the polarizing film of example 9, a PVA film having a thickness of 60 μm was stretched and conveyed in a stretching treatment to obtain a polarizing film of 22.0. Mu.m. In the dyeing process, the concentration of iodine and the immersion time are adjusted to change the iodine concentration, and the thickness of the polarizing film protective film is adjusted to change the moisture content of the polarizing film laminate. Other conditions were the same as in example 9.

(Production of polarizing film laminate)

As a polarizing film protective film, a 30 μm thick transparent protective film (available from ridong electric Co., ltd.) formed of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the obtained polarizing film, and a 49 μm thick transparent protective film having a thickness of 9 μm HC formed on a 40 μm thick cellulose triacetate film (available from Konikoku Meida, trade name "KC4 UY") was bonded to the other surface. The other processes were the same as in example 9.

(Removal of polarizing film)

Conditions for removal were the same as in example 9.

(Production of polarizing film laminate with adhesive layer)

The adhesive layer B was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing an adhesive layer-attached polarizing film laminate of comparative example 7.

Comparative example 8

In the production of the polarizing film of comparative example 7, the concentration of iodine was changed by adjusting the concentration of the aqueous iodine solution and the immersion time in the dyeing treatment, and the amount of moisture in the polarizing film laminate was changed by adjusting the thickness of the polarizing film protective film. As the polarizing film protective film, a transparent protective film (ridong electric company) having a thickness of 20 μm and formed of a modified acrylic polymer having a lactone ring structure was bonded to one surface of the polarizing film. Other conditions were the same as in comparative example 7.

Comparative example 9

In the production of the polarizing film of example 9, a PVA film having a thickness of 75 μm was stretched and conveyed in a stretching treatment to obtain a polarizing film of 28 μm. In the dyeing process, the concentration of iodine and the immersion time are adjusted to change the iodine concentration, and the thickness of the polarizing film protective film is adjusted to change the moisture content of the polarizing film laminate.

Further, the adhesive layer B was transferred onto one surface of the acrylic transparent protective film of the polarizing film laminate, thereby producing an adhesive layer-attached polarizing film laminate of comparative example 9. Other conditions were the same as in example 9.

Comparative example 10

A polarizing film laminate with an adhesive layer of comparative example 10 was produced in the same manner as in comparative example 9 except that the adhesive layer D was transferred to one surface of the acrylic transparent protective film of the polarizing film laminate.

Comparative example 11

A polarizing film laminate with an adhesive layer of comparative example 11 was produced in the same manner as in comparative example 6 except that the adhesive layer E was transferred to one surface of the acrylic transparent protective film of the polarizing film laminate.

4-1 Reliability test

Using the polarizing film laminate 12 obtained in examples and comparative examples, glass plates (loose wave glass slide, product number: S2000423, specification: water edge mill 65×165mm, thickness 1.3 mm) were laminated on both sides of the polarizing film laminate 12 via adhesives 11, 13, respectively, as shown in fig. 4, and were used as samples.

As the adhesive, CS9868US (manufactured by solar corporation) having a thickness of 200 μm was used on the surface of the polarizing film laminate where the adhesive layers a to D were not provided.

After this sample was left at 95℃for 250 hours (95 ℃ C./250H), discoloration and heating redness were evaluated, and after this sample was left at 95℃for 500 hours (95 ℃ C./500H), a polyalkylene evaluation was performed.

4-2 Evaluation criterion

The evaluation criteria for the polyalkylation, the heating reddening and the discoloration are shown below.

< Polyalkylene >

The monomer transmittance of the sample was measured before and after the heating test at 95℃at 500H, and the amount of change ΔTs in the monomer transmittance was determined according to the following formula.

(Type) Δts=ts ₅₀₀－Ts₀

Wherein, ts ₀ is the monomer transmittance of the sample before heating, and Ts ₅₀₀ is the monomer transmittance after heating at 95 ℃/500H.

The case where the variation Δts was negative was evaluated as "multiolefination (decrease in monomer transmittance)" of the sample. In other words, when the transmittance of the monomer after heating at 95℃for 500 hours was the same as that before heating or greater than that before heating, it was evaluated that there was no problem of multiple olefination.

For the above-mentioned samples, the transmittance of the monomers was measured by using a spectrophotometer (product name "DOT-3" manufactured by Toku Kogyo Co., ltd.). The transmittance of the monomer can be obtained based on JIS Z8701.

< Decoloring/heating Red Change >)

Before and after the heating test at 95℃at 250H, the samples were arranged so as to be crossed nicols, and the crossed transmittances (%) at the wavelength of 410nm and at the wavelength of 700nm were measured by the spectrophotometer, respectively, to obtain the respective amounts of change ΔHs ₄₁₀ and ΔHs ₇₀₀.

All cases satisfying the following 2 conditions were evaluated as "discoloration" of the sample.

The change amount ΔH ₄₁₀ is 1% or more

The change amount ΔH ₇₀₀ is 5% or more

In other words, when the amount of change in the orthogonal transmittance at a wavelength of 410nm is less than 1% and the amount of change in the orthogonal transmittance at a wavelength of 700nm is less than 5% due to the heat treatment at 95 ℃/500 hours, it is evaluated that there is no problem of discoloration.

The case where the following conditions were satisfied was evaluated as "heating redness" of the sample.

The variation ΔH ₄₁₀ is less than 1%

The change amount ΔH ₇₀₀ is 5% or more

In other words, when the amount of change in the orthogonal transmittance at a wavelength of 410nm was 1% or more and the amount of change in the orthogonal transmittance at a wavelength of 700nm was less than 5% due to the heat treatment at 95 ℃/500 hours, it was evaluated that there was no problem of heat discoloration.

< Adhesion durability >)

The polarizing film laminate with the adhesive layer was cut into 420mm in the longitudinal direction and 320mm in the transverse direction, and laminated to both sides of an alkali-free glass plate having a thickness of 0.7mm by a laminator. Then, autoclave treatment was performed at 50℃and 5atm for 15 minutes to completely adhere the sample to the alkali-free glass plate. After the sample subjected to the above treatment was subjected to a treatment (heat test) at 95℃for 500 hours, the foaming, peeling and warping states were evaluated by visual observation according to the following criteria.

"Verygood": no change in appearance such as foaming, peeling, warping, etc

"Good" is shown in the following description: the end portions are slightly peeled off or foamed, but there is no practical problem

"DELTA": peeling or foaming at the end portion, but there is no problem in practical use unless it is used for special purposes

"×": There is significant peeling, or foaming at the ends, which is problematic in practical use

< Reworkability >

The polarizing film laminates with an adhesive layer obtained in examples and comparative examples were cut into 200mm in the longitudinal direction and 100mm in the transverse direction, and used as samples. This sample was laminated on alkali-free glass (trade name: EG-XG, manufactured by Corning Co.) having a thickness of 0.7mm using a laminator. Next, autoclave treatment was performed at 50℃and 0.5MPa for 15 minutes to completely seal the samples. For the above samples, the samples were peeled from the alkali-free glass by hand, and the reworkability was evaluated according to the following criteria. For evaluation of reworkability, 3 sheets were produced in the above-described order and repeated 3 times.

And (3) the following materials: the 3 sheets have no residual adhesive and film breakage, and can be peeled off well.

O: a part of the films in the 3 sheets was broken, but could be peeled off by peeling again.

Delta: the 3 sheets all had film breakage, but could be peeled off by peeling again.

X: the 3 sheets had developed a residual adhesive or the film was broken regardless of the peeling of the film several times.

The evaluation results in each example and comparative example are shown in table 2 below.

5. Summary of evaluation results

FIG. 5 is a graph showing the results of examples and comparative examples (excluding comparative example 11) in an x-y orthogonal coordinate system. The x-axis (horizontal axis) represents the iodine concentration (wt.%) of the polarizing film, and the y-axis (vertical axis) represents the moisture content (g/m ²) of the polarizing film laminate.

(1) From the results of the drawing and the common technical knowledge, it is considered that the problem of reddening by heating which occurs in a high temperature state is likely to occur when the iodine concentration is small and the water content is too small, and that the problem of multiple olefination and discoloration is likely to occur when the iodine concentration is large and the water content is too large. In addition, when the iodine concentration is small and the water content is too large, it is considered that the problem of discoloration in a high-temperature and high-humidity state is likely to occur, and in this case, as the iodine concentration increases, the problem of multiple olefination is likely to occur. In particular, a transition region between decolorization and polyethylenization was also observed (comparative examples 13 and 15).

On the other hand, it is found that when the iodine concentration and the water content fall within the predetermined regions, all of the problems of reddening, multiolefination and discoloration by heating can be collectively solved. For example, the results of the examples were all located on the upper side of the separation line "α", i.e., y= (1043-125 x)/240, and the separation line "β", i.e., y= (379-33 x)/70, which is a line passing through the coordinate point (hereinafter referred to as the first coordinate point) representing the graph of the result of example 3 having the smallest moisture amount, i.e., the iodine concentration of 7.0wt.% and the moisture amount of 0.7g/m ², and the coordinate point (hereinafter referred to as the second coordinate point) representing the graph of the result of example 9 having the smallest iodine concentration, i.e., the iodine concentration of 2.2wt.% and the moisture amount of 3.2g/m ², and the separation line "β" passing through the coordinate point (hereinafter referred to as the fourth coordinate point) representing the graph of the result of example 8 having the largest moisture amount, i.e.0 wt.% and the moisture amount of 4.0g/m ², and the coordinate point (hereinafter referred to as the fifth coordinate point) representing the graph of the result of example 2 having the largest iodine concentration, i.0 wt.% and the iodine concentration of the graph of the moisture amount of 10.0 g/m ². Thus, the regions partitioned by these partition lines "α" and "β" can be obtained as lines indicating conditions necessary for solving all the problems of heating reddening, multi-olefination and decoloration in total. The separation lines "α" and "β" are not related to the film thickness of the polarizing film, in other words, can be applied to all polarizing films having a film thickness of about 4 to 20 μm.

In comparative example 6 in which the binder B (amount of acid component in all the monomer components constituting the binder polymer: 0 wt%) was used, although the problem of heat discoloration was not caused by the occurrence of the multiolefination was confirmed, however, in comparative example 11 in which the binder was changed to the binder E (amount of acid component in all the monomer components constituting the binder polymer: 10 wt%), the multiolefination was confirmed. It is speculated from this that if the component containing the acid component is used in excess of a given amount in the monomer component of the binder polymer, the polyalkyleneization is promoted.

(2) As is apparent from the results of the drawing and the general knowledge, in particular, when the iodine concentration and the moisture content of the polarizing film laminate are contained in the region surrounded by a to e, the entire problems of "multi-polarization", "decoloration" and "hot red discoloration" can be collectively solved, and more specifically, the region surrounded by the first coordinate point (a ") connecting the iodine concentration of 7.0wt.% and the moisture content of 0.7g/m ² and the second coordinate point (b") connecting the iodine concentration of 2.2wt.% and the moisture content of 3.2g/m ², the second coordinate point (c) connecting the iodine concentration of 2.2wt.% and the third coordinate point (c) of the moisture content of 4.0g/m ², the fifth coordinate point (d) connecting the third coordinate point "c" and the iodine concentration of 3.0wt.% and the fourth coordinate point (d) of 4.0g/m ² and the fifth coordinate point (e) connecting the fifth coordinate point of the iodine concentration of 34.0 wt.% and the fourth coordinate point (d of 4.0g/m ²).

(3) Similarly, it is understood that, in particular, when the iodine concentration and the moisture content of the polarizing film laminate are contained in the region surrounded by f, b, c, d, g, the polarizing film having a film thickness of about 11 to 20 μm can collectively solve all of the problems of "multi-fluidization", "decoloration", and "heating redness", and more specifically, the region surrounded by the sixth coordinate point (f "in the drawing) and the second coordinate point" b ", the sixth coordinate point (c) and the third coordinate point (d) which connect the iodine concentration of 4.5wt.% and the moisture content of 2.0g/m ², the third coordinate point (d) and the fourth coordinate point (d), the seventh coordinate point (g" in the drawing) and the eighth coordinate point (g) which connect the fourth coordinate point (c) and the seventh coordinate point (g) of 3.3g/m ².

It is considered that, particularly, when the sixth coordinate point "f" is the coordinate point "f-1" having an iodine concentration of 4.0wt.% and a moisture content of 2.3g/m ² and the seventh coordinate point "g" is the coordinate point "g-1" having an iodine concentration of 4.0wt.% and a moisture content of 3.5g/m ², preferable results are obtained.

It is also estimated that, in the case where the iodine concentration and the moisture content of the polarizing film laminate are contained in the regions surrounded by f, b, c, d, g and divided by the line connecting h and i, more specifically, the region surrounded by the eighth coordinate point (h' in the figure) connecting the iodine concentration of 3.3wt.% and the moisture content of 2.6g/m ² and the ninth line connecting the second coordinate point "b" and the second line connecting the second coordinate point "b" and the third coordinate point "c", the third line connecting the third coordinate point "c" and the fourth coordinate point "d", the seventh line connecting the fourth coordinate point "d" and the seventh coordinate point "g", the eighth line connecting the sixth coordinate point "f" and the seventh coordinate point "g", and the ninth line connecting the eighth coordinate point "h" and the moisture content of 6.64 g "in the figure, the polarizing film having a film thickness of about 11 to 20 μm can be obtained with a better result in all of the regions.

(4) It is further understood that, in particular, when the iodine concentration and the moisture content of the polarizing film laminate are contained in the region surrounded by a, h, i, e, namely, the region surrounded by the eleventh line segment connecting the first coordinate point "a" and the eighth coordinate point "h", the tenth line segment connecting the eighth coordinate point "h" and the ninth coordinate point "i", the twelfth line segment connecting the ninth coordinate point "i" and the fifth coordinate point "e", and the fifth line segment connecting the first coordinate point "a" and the fifth coordinate point "e", all the problems of "multi-polarization", "decoloration", and "heating red change" can be solved in a lump, with respect to the polarizing film having a film thickness of about 4 to 11 μm, preferably a film thickness of 4 to 7 μm, and more preferably a film thickness of 4.5 to 6 μm.

It is considered that, particularly when the eighth coordinate point "h" is the sixth coordinate point "f", the ninth coordinate point "i" is the tenth coordinate point (j "in the figure) having an iodine concentration of 7.2wt.% and a water content of 2.0g/m ², preferable results are obtained.

It is also estimated that, in the case where the iodine concentration and the moisture content of the polarizing film laminate are contained in the regions surrounded by a, k, i, e, the region surrounded by the first coordinate point "a" and the eleventh coordinate point (k "in the figure) of the iodine concentration of 6.0wt.% and the moisture content of 1.2g/m ², the thirteenth line segment connecting the eleventh coordinate point" k "and the ninth coordinate point" i ", the twelfth line segment connecting the ninth coordinate point" i "and the fifth coordinate point" e ", and the fifth line segment connecting the first coordinate point" a "and the fifth coordinate point" e ", the polarizing film having a film thickness of about 4 to 11 μm, preferably a film thickness of 4 to 7 μm, more preferably a film thickness of 4.5 to 6 μm, the polarizing film can obtain better results in all of" multi-polarization "," decoloration "and" heating redness ".

It is considered that more preferable results are obtained particularly when the eleventh coordinate point "k" is the coordinate point (k-1) having an iodine concentration of 6.5wt.% and a water content of 1.0g/m ² and the ninth coordinate point "i" is the coordinate point (i-1) having an iodine concentration of 6.5wt.% and a water content of 2.3g/m ².

Claims

1. A polarizing film laminate comprising a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one side of the polarizing film,

The adhesive layer contains an adhesive polymer copolymerized with an acid component, and the amount of the acid component in all monomer components constituting the adhesive polymer is 5 wt% or less,

Wherein the x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is taken as the x-axis and the moisture amount (g/m ²) of the polarizing film laminate is taken as the y-axis has the iodine concentration and the moisture amount contained in a region surrounded by a first line segment connecting the first coordinate point and the second coordinate point, a second line segment connecting the second coordinate point and the third coordinate point, a third line segment connecting the third coordinate point and the fourth coordinate point, a fourth line segment connecting the fourth coordinate point and the fifth coordinate point, and a fifth line segment connecting the first coordinate point and the fifth coordinate point,

The first coordinate point is a coordinate point with an iodine concentration of 7.0wt.% and a moisture content of 0.7g/m ²,

The second coordinate point is a coordinate point with an iodine concentration of 2.2wt.% and a moisture content of 3.2g/m ²,

The third coordinate point is a coordinate point with an iodine concentration of 2.2wt.% and a moisture content of 4.0g/m ²,

The fourth coordinate point is a coordinate point with an iodine concentration of 3.0wt.% and a moisture content of 4.0g/m ²,

The fifth coordinate point is a coordinate point of iodine concentration of 10.0wt.% and moisture amount of 0.7g/m ².

2. The polarizing film laminate according to claim 1, wherein,

The binder polymer has a polydispersity (weight average molecular weight (Mw)/number average molecular weight (Mn)) of 3.0 or less.

3. The polarizing film laminate according to claim 1 or 2, wherein,

The thickness of the polarizing film is 4-20 mu m.

4. A polarizing film laminate comprising a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one side of the polarizing film,

Wherein the polarizing film has an iodine concentration (wt.%) and a water content in the following regions in an x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is taken as an x-axis and the water content (g/m ²) of the polarizing film laminate is taken as a y-axis,

The region is surrounded by a sixth line segment connecting the sixth coordinate point and the second coordinate point, a second line segment connecting the second coordinate point and the third coordinate point, a third line segment connecting the third coordinate point and the fourth coordinate point, a seventh line segment connecting the fourth coordinate point and the seventh coordinate point, and an eighth line segment connecting the sixth coordinate point and the seventh coordinate point,

The sixth coordinate point is a coordinate point with an iodine concentration of 4.5wt.% and a moisture content of 2.0g/m ²,

The seventh coordinate point is a coordinate point having an iodine concentration of 4.5wt.% and a moisture content of 3.3g/m ².

5. The polarizing film laminate according to claim 4, wherein,

The sixth coordinate point is a coordinate point with an iodine concentration of 4.0wt.% and a moisture content of 2.3g/m ²,

The seventh coordinate point is a coordinate point having an iodine concentration of 4.0wt.% and a moisture content of 3.5g/m ².

6. The polarizing film laminate according to claim 4 or 5, wherein,

The thickness of the polarizing film is 11-20 mu m.

7. A polarizing film laminate comprising a polarizing film comprising a polyvinyl alcohol resin and an adhesive layer provided directly or via an optically transparent polarizing film protective film on at least one side of the polarizing film,

Wherein the x-y orthogonal coordinate system in which the iodine concentration (wt.%) of the polarizing film is taken as the x-axis and the moisture amount (g/m ²) of the polarizing film laminate is taken as the y-axis has the iodine concentration and the moisture amount contained in a region surrounded by an eleventh line segment connecting the first coordinate point and the eighth coordinate point, a tenth line segment connecting the eighth coordinate point and the ninth coordinate point, a twelfth line segment connecting the ninth coordinate point and the fifth coordinate point, and a fifth line segment connecting the first coordinate point and the fifth coordinate point,

The eighth coordinate point is a coordinate point with an iodine concentration of 3.3wt.% and a moisture content of 2.6g/m ²,

The ninth coordinate point is a coordinate point of iodine concentration 6.0wt.% and moisture amount 2.6g/m ²,

8. The polarizing film laminate according to claim 7, wherein,

The eighth coordinate point is a sixth coordinate point having an iodine concentration of 4.5wt.% and a moisture content of 2.0g/m ²,

The ninth coordinate point is a tenth coordinate point having an iodine concentration of 7.2wt.% and a moisture amount of 2.0g/m ².

9. The polarizing film laminate according to claim 7 or 8, wherein,

The thickness of the polarizing film is 4-11 mu m.

10. The polarizing film laminate according to any one of claims 1 to 9, wherein,

The polarizing film contains zinc.

11. The polarizing film laminate according to any one of claims 1 to 10, wherein,

For a sample composed of the polarizing film laminate and glass plates laminated on both sides of the polarizing film laminate via an adhesive, the transmittance of the monomer after heating at 95 ℃/500 hours was the same as or greater than the transmittance of the monomer before heating.

12. The polarizing film laminate according to any one of claims 1 to 11, wherein,

For the samples including the polarizing film laminate and glass plates laminated on both sides of the polarizing film laminate via an adhesive, the amount of change in the orthogonal transmittance at a wavelength of 410nm due to a heat treatment at 95 ℃/500 hours was less than 1%, and the amount of change in the orthogonal transmittance at a wavelength of 700nm was less than 5%.

13. The polarizing film laminate according to any one of claims 1 to 11, wherein,

For the sample including the polarizing film laminate and glass plates laminated on both sides of the polarizing film laminate via an adhesive, the amount of change in the orthogonal transmittance at a wavelength of 410nm by a heat treatment of 95 ℃/500 hours was 1% or more and the amount of change in the orthogonal transmittance at a wavelength of 700nm was less than 5%.

14. An optical display panel, comprising:

An optical display unit;

the polarizing film laminate according to any one of claims 1 to 13 bonded directly to one surface of the optical display unit or via another optical film; and

An optically transparent cover plate disposed on the opposite side of the optical display unit along the polarizing film laminate,

The optical display unit, the polarizing film laminate, and the transparent cover plate are bonded together by a transparent adhesive layer filled therebetween in a state of no void.

15. The optical display panel of claim 14 wherein,

The transparent cover plate has a function of a capacitive touch sensor.

16. The optical display panel of claim 15, wherein,

An ITO layer, which is a constituent element of the capacitive touch sensor, is provided between the transparent cover plate and the polarizing film laminate.