KR20150072357A - Pressure-sensitive adhesive composition, polarizer with pressure-sensitive adhesive, and display device - Google Patents

Abstract

The present invention relates to an adhesive composition including an acryl-based copolymer having a carboxyl group, an isocyanate compound, and a terpene phenolic tackifier. The adhesive composition includes 10-50 parts by weight of the isocyanate compound with respect to 100 parts by weight of the acryl-based copolymer having a carboxyl group.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition, a polarizer with a pressure-sensitive adhesive, and a display device,

The present invention relates to a pressure-sensitive adhesive composition, a polarizer with a pressure-sensitive adhesive and a display device.

2. Description of the Related Art [0002] In recent years, as a display device for displaying an image such as a liquid crystal display device, organic electroluminescence or the like, various display type devices have become widespread. Among them, a liquid crystal display device generally has a structure in which a liquid crystal cell containing a liquid crystal component sandwiched between two support substrates such as a glass plate and oriented in a predetermined direction and an optical film such as a polarizing plate, a retardation film, Lt; / RTI > A pressure-sensitive adhesive is used for laminating optical films and for bonding an optical film to a liquid crystal cell.

The polarizing plate used in the liquid crystal display device is arranged so that the stretching shafts of two stretched polarizing films cross each other. Under harsh environments such as high temperature and high humidity, polarizing films are likely to undergo dimensional changes due to expansion and shrinkage, and stress is generated in the polarizing plate. When the generated stress is not alleviated by the pressure sensitive adhesive disposed between the polarizing plate and the liquid crystal cell, the residual stress is unevenly generated in the polarizing plate. As a result, in the two polarizing plates arranged so that the stretching axes of the polarizing films cross each other on the front and back surfaces of the display panel, phase deviations occur, and light leaks from the four peripheral portions of the display portion of the liquid crystal display device, Called dirt occurs.

The occurrence frequency, occurrence pattern, and the like of the white hair described above differ depending on the size of the display panel.

Generally, in a small display panel, a relatively soft pressure-sensitive adhesive (soft type pressure-sensitive adhesive) is used in order to alleviate the stress generated to prevent the occurrence of gray hair (see, for example, Japanese Patent Application Laid-Open No. 10-27990). This soft type pressure-sensitive adhesive is liable to adhere to the processing blade, which tends to deteriorate the suitability of punching, and thus is not suitable for manufacturing a large-sized display panel.

On the other hand, in a large display panel, a relatively hard pressure-sensitive adhesive (hard type pressure-sensitive adhesive) is used to suppress the occurrence of stress in order to prevent the occurrence of white streaks. If this hard type pressure-sensitive adhesive is applied to a small-size display panel, the stress due to shrinkage or the like tends to concentrate on the edge of the display panel, so that the above-mentioned white flakes tend to appear noticeably around the display panel.

In addition, from the viewpoint of enhancing the workability when adhering to an adherend, a suitable tackiness is required for the pressure-sensitive adhesive. The pressure-sensitive adhesive having a suitable tackiness can be temporarily fixed to an adherend. If the tackiness of the tackiness agent is low, the tackiness agent may peel off at the time of temporary stoppage, and the workability is lowered.

As described above, the soft type pressure-sensitive adhesive is said to be suitable for a small-size display panel. However, even if a soft type pressure-sensitive adhesive is currently used for a small-sized display panel, it is difficult to sufficiently prevent the occurrence of white- The same applies to a large display panel, and it is difficult to sufficiently prevent the occurrence of gray hair even if a hard type adhesive is currently used for a large display panel.

Furthermore, a pressure-sensitive adhesive capable of sufficiently preventing the occurrence of white streaks even when used in both small-sized display panels and large-sized display panels has not yet been proposed, and it is necessary to use a pressure-sensitive adhesive separately in small-sized display panels and large-sized display panels.

In addition, from the viewpoint of workability, a suitable adhesive property is required for the pressure-sensitive adhesive.

The object of the present invention is to provide a pressure-sensitive adhesive composition which has suitable adhesive properties and which can prevent the generation of white streaks as compared with the prior art, and which can prevent the occurrence of white stains even when used in both large-sized display panels and small-sized display panels. It is still another object of the present invention to provide a polarizing plate with a pressure-sensitive adhesive and a display device in which an image with few white streaks is displayed.

In the process leading to the present invention, by using an isocyanate compound at a higher content than that of the acrylic copolymer having a carboxyl group, the pressure-sensitive adhesive composition becomes stiffer than before, and the white flag of the large display panel is improved. And thus the occurrence of the disease can be suppressed. Furthermore, it has been found that when the isocyanate compound is used at a higher content than the conventional one, the tackiness tends to deteriorate. In particular, it has been found that a terpene phenolic tackifier (tackifier) is effective for improving the tackiness. The invention has been accomplished.

Specific means for achieving the above object are as follows.

<1> A pressure-sensitive adhesive composition comprising an acrylic copolymer having a carboxyl group, an isocyanate compound and a terpene phenolic tackifier, wherein the content of the isocyanate compound is 10 parts by mass to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer having the carboxyl group.

&Lt; 2 > The pressure-sensitive adhesive composition according to the above-mentioned < 1 >, wherein the softening point of the terpene phenol-based takkyfire is 130 DEG C to 145 DEG C.

<3> The pressure-sensitive adhesive composition according to <1> or <2>, wherein the content of the terpene phenolic tackifier is 2 parts by mass to 10 parts by mass relative to 100 parts by mass of the acrylic copolymer having a carboxyl group.

<4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the acrylic copolymer having a carboxyl group contains 0.1% by mass to 5% by mass of a structural unit derived from an acrylic monomer having a carboxyl group.

(5) The acrylic copolymer having a carboxyl group is a copolymer derived from at least one monomer selected from the group consisting of alkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms and phenoxyethyl (meth) Sensitive adhesive composition according to any one of < 1 > to < 4 >

<6> The acrylic copolymer having a carboxyl group is obtained by copolymerizing a constituent unit derived from acrylic acid, a constituent unit derived from n-butylacrylate and at least one monomer selected from methyl acrylate and phenoxyethyl acrylate Sensitive adhesive composition according to any one of < 1 > to < 5 >

<7> The pressure-sensitive adhesive composition according to <6>, wherein the acrylic copolymer having a carboxyl group further contains a structural unit derived from 2-hydroxyethyl acrylate.

<8> The pressure-sensitive adhesive composition according to any one of <1> to <7>, wherein the isocyanate compound comprises a tolylene diisocyanate compound.

&Lt; 9 >

And a pressure-sensitive adhesive layer formed on the polarizer and formed by the pressure-sensitive adhesive composition according to any one of < 1 > to < 8 >.

&Lt; 10 > a display panel for displaying an image;

The display device according to the above-mentioned < 9 >, which is disposed on at least one surface of the display panel, and a polarizing plate with a pressure-sensitive adhesive.

According to the present invention, there is provided a pressure-sensitive adhesive composition which has suitable adhesive properties and can prevent the generation of white streaks, and which can prevent the occurrence of white stains even when used in both large-sized display panels and small-sized display panels. According to the present invention, there is also provided a polarizer and a display device with a pressure-sensitive adhesive capable of displaying an image with few white streaks.

Hereinafter, the pressure-sensitive adhesive composition of the present invention and a polarizer and a display device with a pressure-sensitive adhesive using the pressure-sensitive adhesive composition will be described in detail.

&Lt; Pressure sensitive adhesive composition &

The pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer having a carboxyl group, an isocyanate compound and a terpene phenolic tackifier, wherein the content of the isocyanate compound is 10 parts by mass to 50 parts by mass relative to 100 parts by mass of the acrylic copolymer having a carboxyl group to be.

The pressure-sensitive adhesive composition of the present invention may further contain other components such as a crosslinking agent and a silane coupling agent, if necessary, in addition to the acrylic copolymer and the isocyanate compound having a carboxyl group.

In the conventional pressure-sensitive adhesive composition, the content of the isocyanate compound is suppressed at most about 5 parts by mass relative to 100 parts by mass of the acrylic copolymer. However, in the present invention, the isocyanate compound is actively incorporated at a high content of 10 parts by mass to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer having a carboxyl group. Thereby, it is possible to obtain a pressure-sensitive adhesive composition which can prevent the generation of white streaks and can prevent the occurrence of white stains even when used in both large-sized display panels and small-sized display panels.

The pressure-sensitive adhesive composition of the present invention can be suitably applied to a large-sized display panel of 19 inches or larger (i.e., a large-sized display device) Small-size display device). In other words, according to the present invention, there is no need to separately prepare a pressure-sensitive adhesive composition which is varied in composition according to the size of the display panel.

In addition, when the isocyanate compound is contained in a high content of 10 parts by mass to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer having a carboxyl group, the tackiness tends to decrease. By incorporating a terpene phenolic tackifier therein, it is possible to effectively suppress the deterioration of the tackiness and provide a pressure-sensitive adhesive composition excellent in workability.

Each component will be described in detail below.

(An acrylic copolymer having a carboxyl group)

The pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer having a carboxyl group (hereinafter sometimes abbreviated as &quot; acrylic copolymer &quot;). The acrylic copolymer having a carboxyl group may have a constituent unit derived from an acrylic monomer having a carboxyl group and may further have a constituent unit derived from another monomer.

Examples of the acrylic monomer having a carboxyl group include acrylic acid (AA), methacrylic acid (MAA), omega -carboxy-polycaprolactone mono (meth) acrylate, succinic acid monohydroxyethyl (meth) (Meth) acrylate, methoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, ) Acrylic acid dimer and the like. These acrylic monomers having carboxyl groups may be used alone or in combination of two or more. Among them, acrylic acid is preferable as an acrylic monomer having a carboxyl group since the reactivity with other monomers during the copolymerization reaction is high and the unreacted monomers can be reduced.

The content ratio of the structural unit derived from an acrylic monomer having a carboxyl group in the acrylic copolymer is preferably from 0.1% by mass to 5% by mass, more preferably from 1% by mass to 5% by mass, still more preferably from 1% by mass to 3% More preferable. When the content is 0.1% by mass or more, crosslinking by an isocyanate compound described later is effectively carried out. When the content is 5% by mass or less, the pot life can be inhibited from being shortened.

Examples of other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, , n-dodecyl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate and the like. These monomers may be used alone or in combination of two or more.

Among them, as other monomers, at least one (meth) acrylate selected from the group consisting of alkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms and phenoxyethyl (meth) acrylate is preferable in view of easy adjustment of the cohesive force and adhesive force of the pressure- And more preferably at least one monomer selected from the group consisting of alkyl acrylates having an alkyl group having 1 to 4 carbon atoms and phenoxy ethyl acrylate, and more preferably n-butyl acrylate as a main component Methyl acrylate and n-butyl acrylate are used in combination, and phenoxyethyl acrylate and n-butyl acrylate are used in combination with n-butyl acrylate as a main component or n-butyl acrylate is used as the main component Methyl acrylate, phenoxyethyl acrylate and n-butyl acrylate as It is more preferred that use.

The content of the constituent unit derived from n-butyl acrylate (BA) in the acrylic copolymer is preferably 75% by mass to 95% by mass, more preferably 80% by mass to 95% by mass, More preferably, it is in mass%.

In the case of using methyl acrylate (MA) and / or phenoxy ethyl acrylate (PHEA) and n-butyl acrylate (BA) as other monomers, the mass ratio of MA and / or PHEA to the BA ((MA + PHEA) / BA) is preferably 0.01 to 1, more preferably 0.1 to 1, and even more preferably 0.1 to 0.7. When the mass ratio of the MA and / or PHEA is 0.01 or more, the polarity of the resin is increased, and even if a large amount of the isocyanate compound is contained, it tends to be easily mixed.

The total content of structural units derived from MA and / or PHEA and BA in the acrylic copolymer is preferably 95% by mass to 99.9% by mass, more preferably 95% by mass to 99% by mass, still more preferably 95% by mass to 98% Is more preferable.

The pressure-sensitive adhesive composition of the present invention is preferably used in combination with other monomers having a functional group other than a carboxyl group. Examples of other monomers having a functional group other than the carboxyl group that can be used in combination include monomers having a hydroxyl group such as 2-hydroxyethyl acrylate (2HEA) and 4-hydroxybutyl acrylate (4HBA), N, N-dimethylacrylamide (DMAA); monomers having an epoxy group such as 4-hydroxybutyl acrylate glycidyl ether (4HBAGE) and glycidyl methacrylate (GMA); and in view of cohesion, Monomer having a hydroxyl group is preferable, and 2-hydroxyethyl acrylate is particularly preferable.

The total amount of constituent units derived from other monomers having a functional group other than the carboxyl group in the acrylic copolymer is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less.

Particularly preferred acrylic copolymers are copolymers containing at least acrylic acid, n-butyl acrylate, and structural units derived from methyl acrylate and / or phenoxyethyl acrylate, and specifically include copolymers of AA / BA / MA, AA / BA / MA / 2HEA copolymer, AA / BA / MA / PHEA copolymer, AA / BA / 2HEA / PHEA copolymer and AA / BA / MA / 2HEA / PHEA copolymer .

The weight average molecular weight of the acrylic copolymer is preferably 300,000 to 2,000,000, more preferably 500,000 to 2,000,000, and even more preferably 700,000 to 1,800,000.

In the present specification, the weight average molecular weight (Mw) of the acrylic copolymer is a value measured by the following method. That is, it is measured according to the following (1) to (3).

(1) An acrylic copolymer solution is coated on a release sheet (release sheet) and dried at 100 DEG C for 2 minutes to obtain a film-like acrylic copolymer.

(2) The film-like acrylic copolymer obtained in the above (1) was dissolved in tetrahydrofuran so as to have a solid content of 0.2% by mass.

(3) The weight average molecular weight (Mw) of the (meth) acrylic copolymer is measured by gel permeation chromatography (GPC) under the following conditions.

<Condition>

GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]

· Column: TSK-GEL GMHXL (using four)

Mobile phase solvent: tetrahydrofuran

· Standard sample: Standard polystyrene

· Flow rate: 0.6 ml / min

Column temperature: 40 ° C

The glass transition temperature (Tg) of the acrylic copolymer is preferably in the range of -50 ° C to -30 ° C, more preferably -48 ° C to -40 ° C. When the Tg is -50 占 폚 or more, the modulus of elasticity can be adjusted, and the durability and the fire resistance are excellent. When the Tg is -30 占 폚 or lower, the viscosity is not extremely deteriorated and the tackiness and the adhesiveness are excellent.

In the present specification, the glass transition temperature (Tg) of the acrylic copolymer is a molar average glass transition temperature determined by the following calculation. Tg ₁ , Tg ₂ , ... in the following formula: And Tg _n are components 1, 2, ... And the glass transition temperature of each homopolymer of component n, calculated in terms of the absolute temperature (K). m ₁ , m ₂ , ... And m _n are the mole fractions of the respective components.

[Calculation formula of glass transition temperature (Tg)] [

The glass transition temperature (Tg) of the homopolymer referred to herein is the glass transition temperature of the monomers described in L. E. Nielsen, Onogi Shigeharu, &quot; Mechanical Properties of Polymers &quot;

The content of the acrylic copolymer in the pressure-sensitive adhesive composition is preferably in the range of 50 mass% to 74 mass% with respect to the total solid content, more preferably in the range of 54 mass% to 69 mass%. When the content of the acrylic copolymer is within the above range, hardness is imparted to the pressure-sensitive adhesive to suppress the generation of stress and effectively inhibit the generation of white streaks.

The polymerization method of the acrylic copolymer in the present invention is not particularly limited, and solution polymerization, emulsion polymerization, suspension polymerization and the like can be applied. Since the treatment process is relatively simple and can be performed in a short time, solution polymerization is preferable as the polymerization method of the acrylic copolymer.

Solution polymerization is generally carried out by adding a predetermined organic solvent, a monomer, a polymerization initiator and a chain transfer agent, which is used as needed, in a polymerization vessel and heating for several hours while stirring in a nitrogen stream or an organic solvent under reflux. The polymerization initiator is not particularly limited, and for example, an azo-based compound can be used.

(Isocyanate compound)

The pressure-sensitive adhesive composition of the present invention contains at least one isocyanate compound. The isocyanate compound is contained in an amount of 10 parts by mass to 50 parts by mass based on 100 parts by mass of the acrylic copolymer having a carboxyl group. When an isocyanate compound is contained in such an amount, white flame is prevented regardless of the size of the display panel. When the content of the isocyanate compound is 10 parts by mass or more, it is possible to prevent the occurrence of white streaks and to prevent the occurrence of white stains even when used in both large-sized display panels and small-sized display panels. When the content of the isocyanate compound is 50 parts by mass or less, the whitening due to the carbon dioxide generated in the reaction of the isocyanate is suppressed and the appearance becomes better. Further, when the content of the isocyanate compound is increased to about 10 parts by mass, the tackiness tends to decrease. However, the pressure-sensitive adhesive composition is excellent in tackiness by containing a terpene phenolic tackifier to be described later.

The content of the isocyanate compound in the pressure-sensitive adhesive composition is preferably 15 parts by mass to 50 parts by mass, more preferably 20 parts by mass to 45 parts by mass, more preferably 30 parts by mass to 40 parts by mass, relative to 100 parts by mass of the total amount of the acrylic copolymer having a carboxyl group It is more desirable to deny it.

As the isocyanate compound, a tolylene diisocyanate compound is suitably used. As the tolylene diisocyanate compound, a tolylene diisocyanate compound derived from tolylene diisocyanate such as a dimer or trimer of tolylene diisocyanate or adduct of a polyol such as tolylene diisocyanate and trimethylol propane can be used have. These tolylene diisocyanate compounds may be used alone or in combination of two or more.

The tolylene diisocyanate compound may be a commercially available product. As a commercially available product of the tolylene diisocyanate compound, &quot; Colonate L &quot; (trade name) manufactured by Nippon Polyurethane Industry Co., Ltd. can be suitably used.

(Terpene phenol based takkyfire)

The pressure-sensitive adhesive composition of the present invention contains a terpene phenolic tackifier. The terpene phenolic tackifier is a resin obtained by copolymerizing a terpene monomer with a phenolic compound. The terpene phenolic tackifier is easily mixed in a pressure-sensitive adhesive composition containing an isocyanate compound in a larger amount than in the prior art, so that the pressure-sensitive adhesive can effectively exhibit adhesiveness.

The terpene phenolic tackifier preferably has a softening point of 130 ° C to 145 ° C, more preferably 130 ° C to 140 ° C, from the viewpoint of mixing properties in the pressure-sensitive adhesive composition.

The softening point of the terpene phenolic tackifier is a value measured based on the softening point test method (ring method) specified in JIS K 2207 (2006 edition).

The terpene phenol-based takkyfire may be used alone or in combination of two or more. Examples of the terpene phenol-based tackifier include monocyclic monoterpenes such as alpha-pinene, beta-pinene and dipentene (limonene), and copolymers of phenol compounds such as phenol, cresol and bisphenol A, and the like.

Terpene phenolic tackifiers may be available on the market. YS Polyster TH130 &quot; (trade name, softening point 130 占 폚), YS Polyster U115 (trade name, softening point 115 占 폚), YS Polyster T145 (trade name, YS Polyster T115 "(trade name, softening point 115 캜)," YS Polyster T140 "(trade name, softening point 140 캜)," YS Polyster T130 " YS Polyster N 125 "(trade name, softening point 125 ° C)," YS Polyster 2115 "(trade name, softening point 115 ° C)," YS Polyster S145 " Mighty Ace K125 "(trade name, softening point 125 ° C)," Mighty Ace G150 "(trade name, softening point 150 ° C)," Mighty Ace G125 " 901 &quot; (trade name, softening point 130 캜), and the like.

The content of the terpene phenolic tackifier in the pressure-sensitive adhesive composition is preferably 2 parts by mass to 10 parts by mass, more preferably 3 parts by mass to 8 parts by mass, per 100 parts by mass of the total amount of the acrylic copolymer having a carboxyl group. When the content of the terpene phenolic tackifier is 10 parts by mass or less, the stress inhibition tends to be more exerted.

(Silane coupling agent)

The pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent. When the pressure-sensitive adhesive composition includes a silane coupling agent, even if a display device (e.g., a liquid crystal display device) in which a polarizing plate is assembled is exposed under a high temperature and high humidity environment, the pressure sensitive adhesive layer tends to be hardly peeled off from the polarizing plate or the liquid crystal cell .

Examples of the silane coupling agent include polymerizable unsaturated group-containing silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3 Mercapto group-containing silane compounds such as mercaptopropyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -methyltrimethoxysilane and the like, Amino group-containing silane compounds such as 3-aminopropylmethyldimethoxysilane, and tris- (3-trimethoxysilylpropyl) isocyanurate. These silane coupling agents may be used alone, or two or more silane coupling agents may be used in combination.

A commercially available silane coupling agent may be used. As a commercially available product of the silane coupling agent, "KBM-403" (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. can be suitably used.

The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably in the range of 0.01 part by mass to 2.0 parts by mass with respect to 100 parts by mass of the total amount of the acrylic copolymer having a carboxyl group. When the content of the silane coupling agent is within the above range, the durability of the pressure-sensitive adhesive layer can be further improved.

In the pressure-sensitive adhesive composition of the present invention, in addition to the above components, various additives such as ultraviolet absorbers, solvents and the like may be appropriately compounded.

<Polarizer with adhesive>

The polarizer with a pressure-sensitive adhesive of the present invention has at least a polarizer and a pressure-sensitive adhesive layer provided on the polarizer and formed by the above-mentioned pressure-sensitive adhesive composition of the present invention.

As the polarizer, for example, a polyvinyl alcohol (PVA) film or the like is generally used. The polarizer can be used, for example, as a polarizing plate composed of, for example, a three-layer structure (for example, TAC / polarizer / TAC) held between protective sheets such as triacetyl cellulose (TAC).

For example, a pressure-sensitive adhesive layer is provided by applying the above-described pressure-sensitive adhesive composition of the present invention to at least one surface of a three-layer structure polarizer of TAC / polarizer / TAC to manufacture a pressure-sensitive adhesive polarizer. In this case, the pressure-sensitive adhesive composition may be provided on the polarizing plate, but is preferably provided on the protective sheet (release sheet) to be peeled off at the time of use. Specifically, the pressure-sensitive adhesive composition of the present invention is coated on a protective sheet (release sheet) and dried to form a pressure-sensitive adhesive layer on the protective sheet to form a pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer is transferred onto the polarizing plate to cure the pressure- A polarizing plate is produced. The pressure-sensitive adhesive composition may be suitably applied by a dipping method using a liquid pressure-sensitive adhesive composition, a coating method, or an inkjet method. Among them, the application of the pressure-sensitive adhesive composition is preferably carried out by a coating method.

The pressure-sensitive adhesive composition applied on the protective sheet (release sheet) is preferably dried using a hot-air drier or the like at a temperature of 70 ° C to 120 ° C for about 1 minute to 3 minutes.

It is preferable that a protective sheet (release sheet) for protecting the exposed surface is provided in close contact with the exposed surface of the adhesive layer provided on the polarizing plate from the viewpoint of protecting the contact surface with the adherend. As the protective sheet, a synthetic resin sheet such as a polyester subjected to release treatment with a releasing agent such as a fluorine resin, paraffin wax or silicone is suitably used so that peeling with the adhesive layer can be easily performed. The protective sheet is peeled off and the surface of the exposed pressure-sensitive adhesive layer is brought into close contact with a glass plate or the like.

The surface (exposed surface) of the polarizing plate on which the pressure-sensitive adhesive layer is not provided may further be provided with a surface protective sheet for protecting the surface thereof. As the surface protection sheet, a protective film or the like which is tack-worked on one side of the PET film is suitably used.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and it is preferably from 1 탆 to 100 탆, more preferably from 5 탆 to 50 탆, and further preferably from 15 탆 to 30 탆 in thickness after drying.

The polarizing plate with a pressure-sensitive adhesive of the present invention can be applied even when the size of the stacked liquid crystal cell is 19 inches wide (260 mm x 415 mm) or more. If the size of the liquid crystal cell is 19 inches wide (260 mm x 415 mm) or larger, the expansion and contraction due to the influence of heat, humidity, etc. of the polarizing plate becomes large. Therefore, in the conventional polarizer with a pressure-sensitive adhesive, since the stress suppression is not sufficient when exposed under high temperature and high humidity, the occurrence of &quot; white hair &quot; occurring around the bezel is suppressed at the time of lighting of a large display device Is difficult. In contrast, in the polarizing plate with a pressure-sensitive adhesive of the present invention, the resin design of the copolymer and the type and amount of the cross-linking agent are appropriately adjusted. Therefore, even when exposed under a high temperature and high humidity, sufficient stress can be restrained and a size of 19 inches wide (260 mm x 415 mm) Of liquid crystal cells. In addition, even when applied to a small-sized display device (liquid crystal display device) of less than 19 inches (and even less than 10 inches), generation of white streaks is suppressed by appropriate stress relaxation property.

Further, in the pressure-sensitive adhesive sheet to which the conventional pressure-sensitive adhesive composition was applied, the portion that did not reach the size of one polarizer was discarded. On the other hand, since the pressure-sensitive adhesive composition of the present invention does not need to be divided according to the size of the polarizer, it can be used for a polarizing plate of a small size even if it does not reach the size of a polarizer of a large size, so that the adhesive sheet can be used without waste.

<Display device>

The display device of the present invention comprises a display panel for displaying an image and a polarizing plate with a pressure-sensitive adhesive of the present invention disposed on at least one side of the display panel. Examples of the display panel include a liquid crystal display panel in which a liquid crystal compound is sealed, an organic electroluminescent display panel, and the like.

As an example of the display device of the present invention, a polarizing plate with a pressure-sensitive adhesive of the present invention is disposed on both sides of a liquid crystal display panel so that the pressure-sensitive adhesive layer is in contact with the surface of the liquid crystal display panel (for example, the surface of the glass plate) A liquid crystal display device having a structure in which a polarizing plate is bonded to both surfaces of a liquid crystal display panel (polarizer / pressure-sensitive adhesive layer / liquid crystal display panel / pressure-sensitive adhesive layer / polarizer structure).

Example

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples unless the scope thereof is exceeded.

(Preparation Example B)

90.25 parts by mass of n-butyl acrylate (BA), 9.5 parts by mass of methyl acrylate (MA), 0.15 parts by mass of 2-hydroxyethyl acrylate (2HEA) in a reactor equipped with a thermometer, a stirrer, , 0.1 part by mass of acrylic acid (AA), 110 parts by mass of ethyl acetate (EAc) and 0.1 part by mass of azobisdimethylvaleronitrile (ABVN) were mixed and replaced with nitrogen in the reactor. Thereafter, while stirring the obtained mixture, the mixture in the reactor was heated to 65 캜 and held for 8 hours to carry out a polymerization reaction. After completion of the polymerization reaction, the reaction mixture was diluted with ethyl acetate and adjusted to a solid content of 27.0% by mass to obtain a solution of resin B (acrylic copolymer) as a BA / MA / 2HEA / AA copolymer.

(Production Examples C to J, A)

A solution of Resin C to J (acrylic copolymer) and a solution of Resin A for Comparative Example were obtained in the same manner as in Production Example B, except that the composition and mixing ratio (parts by mass) of the monomers were changed as shown in Table 1 below.

(Example 1)

- Preparation of pressure-sensitive adhesive composition -

370.4 parts by mass (100 parts by mass as solid content of Resin B) of the resin B as the BA / MA / 2HEA / AA copolymer obtained in Production Example B as an acrylic copolymer and 40 parts by mass of Colonate L as an isocyanate compound 30 parts by mass as an effective component of an isocyanate compound and an isocyanate compound manufactured by Urethane Industries Co., Ltd.), 5 parts by mass of a YS Polyster TH130 (trade name, a product of Yasuhara Chemical Co., Ltd., softening point 130 캜) as a terpene phenolic tackifier, And 0.1 part by mass of KBM-403 were thoroughly stirred and mixed to obtain a pressure-sensitive adhesive composition.

- Production of optical film samples -

The pressure-sensitive adhesive composition was coated on the releasing agent-treated surface of the release film surface-treated with the silicone type releasing agent so that the coated amount after drying was 25 g / cm 2. Next, the applied pressure-sensitive adhesive composition was dried at 100 캜 for 90 seconds by a hot air circulating dryer to form a pressure-sensitive adhesive layer on the release film. Then, a polarizing plate (having a laminated structure of a TAC film / a PVA film / a TAC film by laminating a cellulose triacetate (TAC) film on both sides of a polarizer mainly composed of a polyvinyl alcohol (PVA) film; Thickness: about 190 占 퐉) and the surface of the pressure-sensitive adhesive layer were laminated and bonded to each other, passed through a pressure nip roll, and pressed to obtain a bonded body. This bonded body was cured for 10 days under the environmental conditions of 23 DEG C and 65% RH to prepare a polarizing plate with a pressure-sensitive adhesive having a laminated structure of a release film / pressure-sensitive adhesive layer / polarizing plate as an optical film sample.

-evaluation-

The following evaluation was conducted using the polarizer with a pressure-sensitive adhesive prepared above. The evaluation results are shown in Table 2 below.

(1) Durability (4.3 inches)

A test piece (4.3 inches) of 54 mm × 96 mm (long side) cut at a long side of 45 ° with respect to the absorption axis prepared in the above "Production of optical film sample" was prepared and the release film was peeled from the test piece Respectively. The surface of the pressure-sensitive adhesive layer exposed by peeling was brought into close contact with one side of a 0.7 mm-thick non-alkali glass plate (# 1737, made by Corning), whereby the test pieces were laminated on a glass plate and laminated by using a laminator. Next, this laminate was allowed to stand under the conditions of 23 占 폚 and 65% RH for 24 hours by autoclave treatment (50 占 폚, 5 kg / cm2, 20 minutes). The durability test in which the laminate thus left after being left for 500 hours in a dry environment (80 ° C, 0% RH) under high temperature and low humidity conditions and the durability test for 500 hours in a WET environment (60 ° C, 90% RH) under high temperature and high humidity conditions And a durability test in which H / S environment was repeated by repeating high-temperature and low-temperature cycles (-40 占 폚 for 30 minutes and 85 占 폚 for 30 minutes as one cycle for 300 cycles).

After completion of the durability test, the state of foaming, lifting and peeling was visually observed and evaluated according to the following evaluation criteria.

<Evaluation Criteria>

A: No foaming, lifting and peeling were observed at all.

B: At least one of foaming, lifting and peeling was slightly recognized but acceptable.

C: At least one of foaming, lifting and peeling was recognized remarkably.

(2) gray hair

(2-1) Gray hair phenomenon (small size: 7 inches)

Two specimens were prepared by changing the specimen size to 88 mm × 156 mm (7.0 inches) at the above "(1) Durability (4.3 inches)" and two test specimens were prepared on both sides of a 0.7 mm thick non-alkali glass plate (# 1737, And the polarizing axes were orthogonal to each other to prepare a test sample. Next, this test sample was allowed to stand under the conditions of 23 ° C and 50% RH for 24 hours under autoclave treatment (50 ° C, 5 kg / m 2, 20 minutes), and then dried in a dry environment (70 ° C., 0% . The thus-left test sample was placed on a backlight of a liquid crystal monitor under the conditions of 23 캜 and 50% RH, and the state of nakedness was visually observed and evaluated according to the following evaluation criteria.

<Evaluation Criteria>

A: No gray hair was recognized at all.

B: The gray hair was hardly recognized.

C: The gray hair was slightly recognized, but it was acceptable.

D: The gray hair was greatly recognized.

(2-2) Gray hair phenomenon (large: 19 inches)

Except that the size of the test piece obtained by cutting the polarizing plate with a pressure-sensitive adhesive in the "(2-1) white flash phenomenon (7 inch)" was changed to 240 mm × 427 mm (19 inch) ) &Quot;.

(3) Appearance

The laminate prepared in the same manner as in "(1) Durability (4.3 inch)" was allowed to stand under the conditions of 23 ° C. and 65% RH for 24 hours by autoclave treatment (50 ° C., 5 kg / cm 2, 20 minutes). The exterior appearance of the laminate after the standing was visually observed and evaluated according to the following evaluation criteria.

<Evaluation Criteria>

A: No foaming was found.

B: Foaming was recognized.

(4) Tackiness (probe tack)

The probe tack value of the pressure-sensitive adhesive composition was measured under the conditions of a load of 200 gf / cm 2 (1961.33 mN / cm 2), a velocity of 5 mm / min and a contact time of 0.1 sec by using a probe tack TAC-1000 .

<Evaluation Criteria>

A: Probe value is 80gf (784.532mN) or more, and it has excellent workability.

B: The probe tack value is less than 80 gf (784.532 mN), and the workability is poor.

(Examples 2 to 21 and Comparative Examples 1 to 6)

Except that the kind of the acrylic copolymer, the content ratio (mass part) of the acrylic copolymer and the type of the tachyphyr or the content (mass part) of the tachyphite in Example 1 were changed as shown in Table 2, , A pressure-sensitive adhesive composition was prepared, and a polarizing plate with a pressure-sensitive adhesive was prepared using the pressure-sensitive adhesive composition and evaluated. In Table 2, &quot; unevaluated &quot; indicates that evaluation was impossible because foaming was recognized.

The following are the used takkypires.

· YS Polyster TH130: product of Yasuhara Chemical Co., Ltd., softening point 130 ° C, terpene phenol type

· YS Polyster T140: product of Yasuhara Chemical Co., Ltd., softening point 140 ° C, terpene phenol type

· YS Polyster T115: product of Yasuhara Chemical Co., Ltd., softening point 115 ° C, terpene phenol type

· Fine Crystal D-6011: manufactured by Arakawa Chemical Industries, Ltd., rosin series

As shown in Table 2, in Examples, foaming, lifting and peeling were suppressed irrespective of the DRY environment, the WET environment, and the H / S environment, and good durability was obtained. In addition, in the examples, generation of white streaks was effectively suppressed regardless of the size of the test piece. Further, in the examples, bubbles which are likely to occur during bonding are not curled, and good adhesion is exhibited.

Claims (10)

Wherein the isocyanate compound is contained in an amount of 10 parts by mass to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer having an isocyanate compound and the isocyanate compound having an isocyanate compound and a terpene phenolic tackifier. The method according to claim 1,
Wherein the softening point of the terpene phenolic tackifier is 130 ° C to 145 ° C. The method according to claim 1 or 2,
Wherein the content of the terpene phenolic tackifier is 2 parts by mass to 10 parts by mass based on 100 parts by mass of the acrylic copolymer having the carboxyl group. The method according to claim 1 or 2,
The acrylic copolymer having a carboxyl group contains 0.1 to 5% by mass of a structural unit derived from an acrylic monomer having a carboxyl group. The method according to claim 1 or 2,
The acrylic copolymer having a carboxyl group may contain a constituent unit derived from at least one monomer selected from the group consisting of alkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms and phenoxyethyl (meth) acrylate Lt; / RTI &gt; The method according to claim 1 or 2,
The acrylic copolymer having a carboxyl group may contain a constituent unit derived from acrylic acid, a constituent unit derived from n-butyl acrylate, and a constituent unit derived from at least one monomer selected from methyl acrylate and phenoxyethyl acrylate Lt; / RTI &gt; The method of claim 6,
Wherein the acrylic copolymer having a carboxyl group further contains a structural unit derived from 2-hydroxyethyl acrylate. The method according to claim 1 or 2,
Wherein the isocyanate compound comprises a tolylene diisocyanate compound. A polarizer,
And a pressure-sensitive adhesive layer formed on the polarizer and formed by the pressure-sensitive adhesive composition according to claim 1 or 2. A display panel for displaying an image;
A display device comprising the polarizing plate with a pressure-sensitive adhesive according to claim 9 disposed on at least one side of the display panel.