JP2002331616A - Transparent film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional film deforms or releases a polarizer due to a decrease in an adhesive strength in a humid heat environment in the case of obtaining an optical film having improved adhesive properties. SOLUTION: A transparent film comprises a resin layer which contains a composition different from that of the film on at least one surface, in such a manner that the absolute value of the difference of a solubility parameter from that of the film is 2.0 MPa<0.5> or less. Thus, the adhesive properties of the resin layer to the film is good, and, the resin layer is surface treated, as needed to obtain the film in which the adhesive properties to the adhesive are remarkably improved. The transparent film preferably contains at least (A) a thermoplastic resin A which contains a component having a substituted or non-substituted imide group at a side chain, and (B) a thermoplastic resin B which contains at least a substituted or non-substituted phenyl group and nitrile group at its side chain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to optical characteristics, and
The present invention relates to a novel optical film having excellent film processability.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and smaller, and liquid crystal display devices that take advantage of their light weight and compactness, such as notebook computers, word processors, mobile phones, and personal digital assistants, have been increasingly used. It is becoming. As the applications of these liquid crystal display devices have expanded, it has become necessary to adapt to a high-temperature and high-humidity environment, and similar characteristics have come to be required for various films constituting the liquid crystal display device. Above all, polarizing films are
On both sides of a polarizer made by adsorbing iodine and dichroic dye on highly stretched polyvinyl alcohol film,
Because triacetyl cellulose, which has high moisture permeability and poor moisture absorption dimensional stability, is adhered as a protective film, there is a problem that the performance stability is poor, such as the polarization ability tends to decrease under high temperature and high humidity atmosphere. I have.

[0003] For this reason, it has been proposed to use a new film such as a polycarbonate film, an acrylic film, or an olefin film, which has a lower moisture permeability than triacetyl cellulose, as a polarizer protective film.

[0004]

When a film such as triacetyl cellulose is incorporated in a polarizing film or a liquid crystal display device, it is bonded to another material using an adhesive or an adhesive. In particular, when used as a polarizer protective film and bonded to a stretched polyvinyl alcohol-based polarizer, it is necessary to maintain sufficient adhesive strength against stress accompanying shrinkage deformation of the polarizer corresponding to environmental changes. A conventional polarizing film maintains its characteristics by saponifying the surface of a triacetyl cellulose film, activating the surface, and firmly adhering it using a polyvinyl alcohol-based adhesive. Various films proposed in place of triacetyl cellulose have basic properties such as moisture permeability and birefringence that are superior to those of triacetyl cellulose, but cannot be adapted to a unique bonding process, and new adhesive properties There is a need for technology for granting.

To deal with such problems, the film surface is subjected to an electrical treatment such as a corona discharge treatment or a spark treatment, a plasma treatment at a low or normal pressure, an ultraviolet irradiation treatment in the presence or absence of ozone, Acid treatment with chromic acid, etc.
A method of activating by a surface activation treatment such as a flame treatment or a primer treatment of a silane or titanium system has been attempted.

Although these treatments have a certain effect, the resulting film has insufficient adhesion to the polarizer. In addition, even when a sufficient adhesive strength is obtained in the initial stage, there is a problem that the adhesive strength is reduced in a moist heat environment and the polarizer is deformed or peeled off. The reason why the adhesive strength is insufficient is that the film used does not show sufficient reactivity under the conditions of the surface treatment, and has an insufficient affinity with the adhesive.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 2000-356714, it has been proposed to form a hydrophilic resin layer having a high affinity for an adhesive. Although the affinity was high, the adhesiveness between the resin layer and the film was insufficient, and it was difficult to obtain desired characteristics. Further, when the obtained polarizing film is placed in a moist heat environment, there is a problem that the hydrophilic resin layer absorbs water and the adhesive strength is reduced.

[0008]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies and found that the absolute value of the difference between the solubility parameter of the transparent film and that of the transparent film was 2.0 MPa ^0.5 The following problems can be solved by applying a known surface treatment means to the surface of the resin layer, if necessary, as a composite film having the following resin layer, and a film having good adhesion can be easily obtained. The present invention has led to what can be done.

That is, the present invention provides a resin film having a composition different from that of the transparent film and having an absolute value of a difference in solubility parameter from the film of 2.0 MPa ^0.5 or less on at least one surface of the transparent film. A transparent composite film characterized by having a transparent composite film. The film of the present invention has a light transmittance of 85% or more, a haze of 2% or less, and a retardation value of 10 nm or more and 1000 nm or less.
Further, the film of the present invention has a light transmittance of 85% or more, a haze of 2% or less, and a retardation value of less than 10 nm.

In the composite film of the present invention, the transparent film comprises at least (A) a thermoplastic resin A comprising a component having a substituted or unsubstituted imide group in a side chain;
It is preferable that the film contains a thermoplastic resin B having at least a substituted or unsubstituted phenyl group and a nitrile group in a side chain.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The transparent composite film of the present invention has a composition different from that of the transparent film on at least one surface of the transparent film, and the absolute value of the difference in solubility parameter from the film is 2.0 MPa ^0.5 It has the following resin layer.

A transparent film that can be used in the present invention
A wide variety of known films can be used. General
Typically, polyethylene terephthalate, polyethylene na
Polyester resins such as phthalate, cellulosedia
Acetate, cellulose acetate butyrate, cellulose
Acetate phthalate, cellulose acetate propylate
Cellulose ester resins such as onate or the like
Derivatives, polystyrene, syndiotactic police
Polystyrene resin such as styrene, polyvinyl chloride,
Polyvinylidene chloride, polymethylpentene, polymer
Terminal olefin resins such as tyl methacrylate
Recarbonate resin, polyester carbonate tree
Fat, polyarylate resin, polysulfone resin, poly
Cyclos such as ether sulfone resins and norbornene resins
Olefin resins or their derivatives, olefin polymers
Imide-based resins such as reimide-based resins and glutarimide-based resins
Resins can be mentioned. Among the above resins, molecules
Birefringence due to the orientation of the material and the photoelastic coefficient is relatively small
Cycloolefin resin, polystyrene resin,
A mid resin can be preferably used. These resins
Is preferably 100 ° C. or higher, and more preferably
It is preferably 120 ° C, more preferably 140 ° C or more.
You. A preferred photoelastic coefficient has an absolute value of 30 × 10
^-13cm^Two/ Dyn or less, more preferably 10 ×
10^-13cm ^Two/ Dyn or less, more preferably 5
× 10^-13cm^Two/ Dyn or less. The photoelastic coefficient is
If it is larger than that, when used as a polarizer protective film,
The contraction stress of the polarizer makes it easier to develop a phase difference,
It may cause a decrease in the optical characteristics of the optical film.
Not good. The retardation of the transparent film is less than 10 nm.
Preferred, more preferably less than 5 nm, even more preferred
Or less than 3 nm. Further, the light of the transparent film
The transmittance is preferably 85% or more. Also, the transparent
The phase difference in the film thickness direction of the film
It is important to improve the viewing angle characteristics of the film.
A preferable thickness direction retardation is 50 nm or less.
More preferably 30 nm or less, and even more preferably 10 nm or less.
nm or less. The phase difference in the film thickness direction
The maximum refractive index in the system plane is nx, refraction in the direction orthogonal to nx
Index is ny, refractive index in the film thickness direction is nz, film
| (Nx + ny) / 2-nz) where d is the thickness of
| × d.

In another embodiment of the present invention, the transparent film preferably has a retardation of 10 nm or more and 1000 nm or less.

The moisture permeability of the film of the present invention can be represented by moisture permeability. In particular, durability at a high temperature is required, and it is important that the moisture permeability at 70 ° C.-90% relative humidity is small. . Preferably, 1000 g / (m ² · 2
4 hr) or less, more preferably 500 g / (m ² · 24)
hr) or less, more preferably 400 g / (m ² · 24 h)
r) The following is true. Too small a water vapor transmission rate is not preferable because it may hinder drying of water remaining in the adhesive or the polarizer. Generally, the lower limit of the preferable moisture permeability is 10 g.
/ (M ² · 24 hr) or more, more preferably 50
g / (m ² · 24 hr), more preferably 100 g /
(M ² · 24 hr) or more, but is not limited thereto.

Particularly preferred resins constituting the transparent film of the present invention include (A) a thermoplastic resin A having a substituted or unsubstituted imide group in the side chain, and (B) a substituted or unsubstituted (B) side chain at least. It is a resin composition containing a thermoplastic resin B having a phenyl group and a nitrile group.

The preferred thermoplastic resin (A) in the resin composition is at least one olefin (alkene)
(A binary or higher multi-component copolymer) containing a repeating unit derived from the above and a repeating unit having at least one type of substituted or unsubstituted maleimide structure. The olefin / maleimide copolymer can be prepared by known methods, for example, as described in JP-A-5-59193 and JP-A-5-59193.
As described in 195801, JP-A-6-136058 and JP-A-9-328523, two kinds of monomers are directly copolymerized or graft copolymerized to one polymer. An imide bond can be introduced into a precursor polymer described below by a polymer reaction to obtain the precursor polymer. Particularly preferably, the thermoplastic resin (A) has a repeating unit derived from at least one olefin (alkene) represented by the following formula (3) and at least one substituted group represented by the following formula (4). Alternatively, it contains a repeating unit having an unsubstituted maleimide structure.

[0017]

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(Here, R ⁵ , R ⁶ and R ⁷ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms.)

[0019]

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(Where R ¹ is hydrogen, C 1-18
Or a cycloalkyl group having 3 to 12 carbon atoms. Examples of preferred olefins include isobutene, 2-methyl-1-butene, 2-methyl-1-pentene, 2-methyl-1-hexene, 1-methyl-1-heptene, 1-isooctene, and 2-methyl-1-. Octene, 2-ethyl-1
-Pentene, 2-ethyl-2-butene, 2-methyl-2
Olefin monomers such as pentene and 2-methyl-2-hexene. Preferred substituted maleimides are those wherein the N substituent is methyl, ethyl, n-propyl, i-
Propyl, n-butyl, i-butyl, s-butyl, t-
Butyl, n-pentyl, n-hexyl, n-heptyl,
N-substituted maleimides such as n-octyl, lauryl, stearyl, cyclopropyl, cyclobutyl and cyclohexyl.

These copolymers may contain other vinyl monomers. Examples of the vinyl monomer include acrylic monomers such as methyl acrylate and butyl acrylate, methacrylic monomers such as methyl methacrylate and cyclohexyl methacrylate, and vinyl ester monomers such as vinyl acetate. Monomer, a vinyl ether monomer such as methyl vinyl ether, an acid anhydride having an unsaturated double bond such as maleic anhydride, and a styrene monomer such as styrene and α-methylstyrene. It may be contained. These olefin monomers, substituted or unsubstituted maleimide monomers, and the third component may be used in combination of a plurality of monomers as necessary.
By including the third component to such an extent that the optical properties are not impaired, the heat resistance of the thermoplastic copolymer (A) can be improved or the mechanical strength can be increased.

The olefin / maleimide copolymer is obtained by reacting an amine compound with maleic acid, the above-mentioned olefin-based monomer, and if necessary, the above-mentioned third component or the precursor polymer containing the unsubstituted or substituted maleimide. You can also get it. Preferred amine compounds include alkylamines such as methylamine, ethylamine n-propylamine, i-propylamine, n-butylamine, s-butylamine, t-butylamine, and cyclohexylamine, ammonia, dimethylurea, diethylurea, and the like. be able to.

The olefin / maleimide copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, and an alternating copolymer, but is preferably an alternating copolymer. The olefin / maleimide copolymer is more preferably a maleimide unit,
R in the formula (2) contains at least one maleimide unit which is an alkyl group selected from a methyl group, an ethyl group, an isopropyl group and a cyclohexyl group, and as an olefin unit, R ¹ in the formula (1) is hydrogen. Yes,
At least one of R ² and R ³ each being a methyl group;
It is a copolymer containing various olefin units. More preferably, the olefin / maleimide copolymer contains an N-methylmaleimide unit as a maleimide unit and an isobutylene unit as an olefin unit. It is particularly preferred that the thermoplastic copolymer (A) of the present invention is an alternating copolymer of N-substituted maleimide and isobutene.

In the olefin / maleimide copolymer,
The content of the maleimide component is preferably 30 mol% or more and less than 80 mol%, more preferably 40 mol% or more and 60 mol% or less, based on the total repeating units in the copolymer. If it exceeds this range, the heat resistance and mechanical strength of the obtained film will be impaired. When the third component is added, the content of the third component is preferably 5 mol% or more and 30 mol% or less. The remainder of the olefin / maleimide copolymer is olefin units. The olefin / maleimide copolymer may contain a maleimide unit and an olefin unit as main components (preferably, the total of the maleimide unit and the olefin unit is 70 mol% or more of the thermoplastic copolymer (A)). Particularly preferred.

With respect to the required heat resistance, the glass transition temperature is preferably 80 ° C. or higher, more preferably 100 ° C.
C. or higher, more preferably 130.degree. C. or higher.

The preferred range of the weight average molecular weight is as follows:
A copolymer of 1 × 10 ⁴ or more and 5 × 10 ⁵ or less is used.

As another preferable thermoplastic resin (A) in the resin composition, a glutarimide-based thermoplastic resin can be used. The glutarimide resin,
JP-A-2-153904, JP-A-5-20225
No. 3, JP-A-6-500807, etc., it has a glutarimide structural unit and a methyl acrylate or methyl methacrylate structural unit.

A preferred glutarimide is represented by the following formula (5):

[0029]

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A glutarimide unit represented by the formula (wherein, R ² , R ³ and R ⁴ independently represent hydrogen or C 1 to C 1)
Two unsubstituted or substituted alkyl, cycloalkyl and aryl groups. ) Is a glutarimide-based resin.

Preferred glutarimide units constituting the glutarimide resin used in the present invention include R
² , R ³ is hydrogen or a methyl group, and R ⁴ is a methyl group or a cyclohexyl group. The glutarimide unit may be a single unit or a plurality of units.

A preferred second structural unit constituting the glutarimide resin is a unit composed of an acrylic ester or a methacrylic ester. Preferred acrylate or methacrylate structural units include methyl acrylate, ethyl acrylate, methyl methacrylate, methyl methacrylate, and the like. Another preferable imidizable unit is N-methylmethacrylamide or N-ethylmethacrylamide.
It is an alkyl methacrylamide. These second structural units may be used alone or in combination.

[0033] The content of the glutarimide unit in the glutarimide resin is 20% by weight or more based on the total repeating units in the glutarimide resin. The preferred content of the glutarimide unit is from 20% by weight to 9% by weight.
It is 5% by weight, more preferably 50-90% by weight, even more preferably 60-80% by weight. When the glutarimide unit is smaller than this range, the heat resistance of the resulting film may be insufficient and the transparency may be impaired. If the ratio exceeds this range, the heat resistance is unnecessarily increased to make it difficult to form a film, and the mechanical strength of the obtained film becomes extremely brittle, and the transparency may be impaired.

The glutarimide resin may further have, if necessary, a third structural unit copolymerized.
Preferred examples of the third structural unit include styrene, substituted styrene, styrene monomers such as α-methylstyrene, acrylic monomers such as butyl acrylate, and nitrile monomers such as acrylonitrile and methacrylonitrile. And a structural unit obtained by copolymerizing a maleimide monomer such as maleimide, N-methylmaleimide, N-phenylmaleimide, or N-cyclohexylmaleimide. These may be directly copolymerized with the glutarimide unit and the imidizable unit in the glutarimide resin, or may be graft copolymerized with the resin having the glutarimide unit and the imidizable unit. It may be polymerized. When the third component is added, the content in the glutarimide resin is 5 mol% or more,
It is preferably at most 30 mol%.

The glutarimide resin is disclosed in US Pat.
No. 4425, U.S. Pat.
As described in JP-A-53904, for example, a resin obtained using methacrylic acid methyl ester or the like as a main raw material is used as a resin having imidizable units, and the resin having imidizable units is converted to ammonia or a substituted amine. Can be obtained by imidation using
Further, as shown in Japanese Patent Application Laid-Open No. 02-153904, the glutarimide resin can be obtained by imidization using a resin mainly composed of N-methylacrylamide and methyl methacrylate.

When the glutarimide resin is obtained, a unit composed of acrylic acid, methacrylic acid, or an anhydride thereof may be introduced as a reaction by-product into the glutarimide resin. The presence of such a structural unit, particularly an acid anhydride, is not preferred because it reduces the total light transmittance and haze of the transparent film. It is desirable that the content of acrylic acid or methacrylic acid be 0.5 meq or less, preferably 0.3 meq or less, more preferably 0.1 meq or less per 1 g of the resin. The glutarimide resin preferably has a weight average molecular weight of 1 × 10 ⁴ to 5 × 10 ⁵ .

As the preferred thermoplastic resin B in the resin composition, an acrylonitrile-styrene copolymer can be preferably used. Particularly preferably, the thermoplastic resin (B) contains an unsaturated nitrile unit represented by the following formula (6) and a styrene-based unit represented by the following formula (7).

[0038]

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(Here, R ⁸ and R ⁹ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms.)

[0040]

Embedded image

(Wherein R ¹⁰ and R ¹¹ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms;
¹² represents hydrogen, an alkyl group having 1 to 8 carbon atoms, a halogen, a hydroxyl group, an alkoxy group or a nitro group. ).

Preferred examples of the unsaturated nitrile compound constituting the thermoplastic resin B include α-substituted unsaturated nitriles such as acrylonitrile and methacrylonitrile;
It is a nitrile compound having an α, β-disubstituted olefinically unsaturated bond such as fumaronitrile.

Examples of the styrene compound constituting the thermoplastic resin B include unsubstituted or substituted styrene compounds such as styrene, vinyltoluene, methoxystyrene and chlorostyrene, and α-substituted styrene compounds such as α-methylstyrene. Can be used.

The acrylonitrile / styrene copolymer may contain a third component, if necessary. An example of a preferred third component is an acrylic monomer such as butyl acrylate, or an olefin monomer such as ethylene or propylene, and one or two or more of these monomers are copolymerized. Thereby, the flexibility of the obtained film can be increased. Also,
The other third component is an N-substituted maleimide. In particular, by using phenylmaleimide as a copolymer component, the heat resistance of the copolymer can be improved.

The thermoplastic resin B can be obtained by directly copolymerizing these monomers. Alternatively, the corresponding monomers may be graft-copolymerized with a styrene-based or unsaturated nitrile-based polymer. . Further, a preferable copolymer can be obtained by graft-polymerizing a styrene-based monomer or an unsaturated nitrile-based monomer to an acrylic polymer having rubber elasticity. In a particularly preferred monomer, the unsaturated nitrile component is acrylonitrile, and the styrene-based monomer is styrene. Further, the thermoplastic resin B is 1 × 1
0 preferably has a weight average molecular weight of ⁴ to 5 × 10 ^5. These copolymers are known as AS resins and AAS resins.

In the thermoplastic resin B, the content of the unsaturated nitrile component in the preferred copolymer is preferably from 20 to
It is preferably 60% by weight, more preferably 20 to 50% by weight. Further, the content of the styrene component is 4
It is preferably from 0 to 80% by weight, more preferably from 50 to 80% by weight.
% By weight. Particularly, when the former is 20 to 30% by weight and the latter is 70 to 80% by weight, more preferable results are obtained. If the styrene-based or nitrile-based component exceeds this range, the compatibility with the thermoplastic resin A becomes poor, and the haze of the obtained transparent film may be undesirably increased.

When the third component is added, the content in the thermoplastic resin B is preferably 5 mol% or more and 30 mol% or less. Particularly preferred nitrile and styrene components differ depending on the thermoplastic resins A and B used.

It is preferable that the thermoplastic resin B has a weight average molecular weight of 1 × 10 ⁴ to 5 × 10 ⁵ .

When a film having a small retardation is obtained, when the thermoplastic resin A is mainly the olefin / maleimide copolymer, and when the thermoplastic resin B is a copolymer mainly composed of acrylonitrile and styrene, acrylonitrile and acrylonitrile are used. The content of styrene is preferably 20 to
By setting the content of styrene to 50% by weight, more preferably 25 to 40% by weight, and the content of styrene to preferably 50 to 80% by weight, more preferably 55 to 75% by weight, a good composition can be obtained in a wide composition range. When the film is compatible and has a total light transmittance of 85% or more and a haze of 2% or less, a film can be obtained. In particular, by setting the content of acrylonitrile to 26 to 29% by weight and the content of styrene to 71 to 74% by weight, the thermoplastic resin B and the thermoplastic resin A have a composition range of 0 to 80% by weight. Shows good compatibility, and is extremely transparent with a total light transmittance of 90% or more and a haze of 1% or less, and a film having an extremely small retardation of 5 nm or less, preferably 3 nm or less. . Further, since the film made of the composition has a feature that the retardation is hardly developed even when stretched, the film is stretched uniaxially or biaxially, and has excellent mechanical strength, and furthermore, in-plane of the film and It is characterized in that a film having a small retardation in both thickness directions can be obtained. Stretching is known in the art, such as transverse stretching using a tenter, longitudinal stretching using a roll, free-end uniaxial stretching, and sequential combination of these, sequential biaxial stretching, and simultaneous biaxial stretching that simultaneously stretches vertically and horizontally. Can be used.

When the thermoplastic resin A is mainly the glutarimide resin and the thermoplastic resin B is a copolymer mainly composed of acrylonitrile and styrene,
The content of acrylonitrile is preferably 20 to 50% by weight, more preferably 25 to 40% by weight, and the content of styrene is preferably 50 to 80% by weight, more preferably 55 to 75% by weight. By doing so, good compatibility is exhibited in a wide composition range, and when the film is formed, a film having a total light transmittance of 85% or more and a haze of 2% or less can be obtained.

Particularly, when a film having a small retardation is obtained by using the glutarimide resin, the glutarimide unit is 60 to 80% by weight, the unit composed of methyl methacrylate is 20 to 40% by weight, and the acid content is 0 to 40% by weight. By adjusting the content of acrylonitrile to 26 to 29% by weight and the content of styrene to 71 to 74% by weight in the thermoplastic resin B, the thermoplastic resin B
And the glutarimide resin exhibit good compatibility over a wide composition range, are extremely transparent with a total light transmittance of 90% or more and a haze of 1% or less, and have a phase difference of 5 nm or less, preferably 3 nm or less. A film having a small retardation can be obtained. Further, a film comprising the composition,
Since it has the feature that the retardation is extremely difficult to develop even when stretched, it is stretched uniaxially or biaxially to obtain a film with excellent mechanical strength and a small retardation both in the film plane and in the thickness direction. It has the feature that it can be. Stretching is known in the art, such as transverse stretching using a tenter, longitudinal stretching using a roll, free-end uniaxial stretching, and sequential combination of these, sequential biaxial stretching, and simultaneous biaxial stretching that simultaneously stretches vertically and horizontally. Can be used.

The transparent film is composed of a single resin or a resin composition as described above, but the transparent film may be a composite film composed of a plurality of layers composed of the resin or the composition. Absent.

The transparent film can be obtained by a known film forming method, and the film forming method is not particularly limited. Preliminary drying of the resin and pellets used before film formation is useful for preventing defects such as foaming of the film. In particular, when an imide-based resin or a cycloolefin-based resin is used, it has a characteristic that a retardation due to molecular orientation during processing is hard to appear, and therefore, a film formation by a melt molding method is also a preferable method. When a film is formed by a melt molding method, a known method such as a melt extrusion method such as a T-die method or an inflation method, a calender method, a hot press method, or an injection molding method can be employed. T in that it is easy to obtain a film of
A melt molding method using a die is preferred. Further, a solution casting method is also a preferable method in that a film having extremely uniform thickness accuracy can be obtained. By these film forming methods, it is possible to obtain an optically isotropic transparent film having no defects such as die lines, a small variation in film thickness of 5% or less, and a small retardation.

The transparent film has on at least one surface thereof a resin layer whose absolute value of the difference between the film and the solubility parameter is 2.0 MPa ^0.5 or less. As the resin layer, a known resin layer can be used. As a preferred resin layer, generally, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose phthalate, cellulose acetate propionate, cellulose acetate butyrate, and
Cellulose ester resins such as cellulose acetate phthalate, methyl cellulose, ethyl cellulose, alkyl cellulose ether resins such as ethyl hydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose ether resins such as hydroxypropyl cellulose, nitrocellulose resins, or these cellulose resins Derivatives of resins, polyvinyl ester resins such as polyvinyl acetate and polyvinyl propionate, and saponified products thereof, olefin-vinyl ester resins of olefins such as ethylene and propylene with vinyl esters such as vinyl acetate and vinyl propionate, and The saponified product, isobutylene-maleic anhydride resin and its hydrolyzate, alkali metal salt, polyacrylic acid and polymer Acrylic acid resins and copolymers of them with methacrylic acid methyl ester and acrylic acid methyl ester; copolymerized polyamide resins such as copolymerized polyamides of 66 amino acids consisting of caprolactam, hexamethylenediamine and adipic acid; methoxymethyl Polyamide-based resin such as a modified polyamide 6,
Polyvinyl ether resins such as polyvinyl methyl ether and polyvinyl ethyl ether, polyvinyl butyral resins, polyvinyl formal resins, polystyrene resins such as polystyrene and syndiotactic polystyrene, polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate Such as terminal olefin resin, polycarbonate resin, polyester carbonate resin, polyarylate resin, polysulfone resin, polyethersulfone resin, cycloolefin resin such as norbornene resin or derivatives thereof, olefin-maleimide resin and Examples include imide resins such as glutarimide resins and hydrophilic polyester resins such as sulfonated polyesters. It is particularly preferable that the resin layer contains a compound capable of generating at least one functional group selected from a hydroxyl group, an amino group and a carboxyl group by hydrolysis with an acid or an alkali.
Specific examples of such compounds include an ester group,
It is a compound having a carbonate group, a substituted or unsubstituted amide group, a substituted or unsubstituted imide group, an ether group, and an acid anhydride group.

The solubility parameters of these resins can be measured and calculated by known methods. In particular, the solubility parameter of Fedors determined from the contribution of each atomic group (RF Fedors, Polym. Eng. Sc.
i. , Vol14, p147, p472, (197
4). And J. Brandrup et a
l. , "Polymer Handbook", 4th
Ed. , John Wiley & Sons, New
York, 1999, Ch. 7, Table
3. Is useful because the solubility parameters of various polymers can be easily determined. The absolute value of the difference between the solubility parameters of the transparent film and the resin layer is preferably 2.0 MPa ^0.5 or less, more preferably 1.5 MPa ^0.5
Hereinafter, by setting the pressure to 1.0 MPa ^0.5 or less, a composite film having excellent adhesion between the resin layer and the transparent film can be obtained. Since the value of the solubility parameter of the preferred resin varies depending on the solubility parameter of the transparent film to be composited, a resin system capable of continuously changing the solubility parameter is preferred. Among the above preferred resins, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose phthalate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose ester resins such as cellulose acetate phthalate, methyl cellulose, ethyl cellulose, and ethyl Alkyl cellulose ether resins such as hydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose ether resins such as hydroxypropyl cellulose, nitrocellulose resins, or derivatives of these cellulose resins, polyvinyls such as polyvinyl acetate and polyvinyl propionate Ester resins, saponified products thereof, olefins such as ethylene and propylene Olefin-vinyl ester resin and its saponified product with vinyl ester such as vinyl acetate and vinyl propionate, isobutylene-maleic anhydride resin and its hydrolyzed product, alkali metal salt, polyacrylic acid and polymethacrylic acid resin and their methacrylic acid Copolymers such as acid methyl esters and acrylic acid methyl esters, copolymerized polyamide resins such as copolymerized polyamides of 66 amino acids consisting of caprolactam, hexamethylenediamine and adipic acid, and methoxymethylated polyamides 6 A polyamide-based resin is a preferable resin because the solubility parameter can be continuously changed over a wide range by changing the composition. The cellulose-based resin can be obtained by substituting the hydroxyl group of cellulose with various substituents to obtain a cellulose derivative such as the cellulose ester-based resin or the alkyl cellulose ether-based resin or the cellulose ether-based resin. It is possible to continuously change the solubility parameter by changing the substitution ratio of the alcohol residue of cellulose. The solubility parameter of the vinyl ester resin can be continuously changed by changing the ratio of saponification of the vinyl ester or the copolymerization ratio with the olefin. It is also possible to use a curable resin layer which is cured by heat or energy rays such as ultraviolet rays and electron beams. As a preferred curable resin layer, as the organic coating layer,
Melamine resin-based, acrylic resin-based, urethane resin-based, alkyd resin-based, fluorine-containing resin-based, and as an organic-silicone composite system, polyester polyol or etherified methylol melamine alkyltrialkoxysilane, tetraalkoxysilane One containing a partially hydrolyzed product is exemplified. Further, silicone resins such as partial hydrolysates of aminosilane and epoxysilane, partial hydrolysates of silane coupling agents and alkyltrialkoxysilanes / tetraalkoxysilanes, and hydrolysates of colloidal silica and alkyltrialkoxysilanes are also suitable. Can be used.

The upper limit of the thickness of the resin layer is preferably 10
μm or less, more preferably 1 μm or less, and still more preferably 0.5 μm or less. Although the lower limit of the thickness of the resin layer is not limited as long as the adhesiveness can be maintained, it is generally 0.01 μm.
m, preferably 0.1 μm or more.

The resin layer needs to have durability against humidity like the transparent film. When the transparent composite film of the present invention is formed using a layer made of a resin having solubility in water as the resin layer, and then bonded to a polarizer using an aqueous adhesive to form a polarizing film, the adhesive contains Since the resin layer absorbs water and becomes a viscous layer, there is a problem that the drying of the polarizing film is difficult to proceed and it takes time to develop the adhesive strength. Further, although the obtained polarizing film also shows good adhesiveness in a dry state, there is a problem that the resin layer absorbs water under high humidity conditions and cannot maintain the adhesiveness with the adhesive. Therefore, the resin layer has a water-soluble weight fraction (water-soluble component) of preferably 50% or less, more preferably 10% or less. Further, the water absorption is preferably 50
%, More preferably 30% or less, further preferably 10% or less.

The method of laminating the resin layer on the transparent film is not particularly limited. After dispersing in a suitable solvent or water, a method of coating the transparent film, a method of laminating a film composed of the resin layer to the transparent film by heat or the like, a co-extrusion method for forming the transparent film into a film. Such as laminating by
It is possible to use a known laminating method.

In the case of coating by dissolving or dispersing the resin forming the resin layer in a solvent, a known coating method can be used. Preferred examples of the coating method include a bar coater, a doctor knife, a Meyer bar, a roll, a T-die, and a comma coater.
Known solvents can be used for coating. Generally, aromatics such as toluene, xylene and anisole, cyclic ethers such as dioxane, dioxolan, tetrahydrofuran and pyran, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone Solvents such as carbonate solvents such as dimethyl carbonate and the like, and alcohol solvents such as methyl alcohol and isopropyl alcohol can be used. Also, halogenated hydrocarbon solvents such as methylene chloride and trichloroethane, and highly polar non-halogen solvents such as dimethylformamide and dimethylacetamide can be used. These solvents can also be used by mixing with each other, it is also preferable to control the evaporation rate by combining a solvent having a low boiling point and a solvent having a high boiling point, and to obtain the resin layer having excellent surface properties. Is the way. The solid content concentration of the solution can be appropriately adjusted depending on the appearance of the coating film and the required thickness of the resin layer.
1 to 50% by weight, preferably 1 to 10% by weight
It is. After coating the solution on the transparent film,
The resin layer is dried in a drying oven and, if necessary, is further heated or irradiated with ultraviolet rays or electron beams to cure the resin layer. The amount of residual solvent in the resin layer is preferably 5% by weight or less, more preferably 1% or less, and still more preferably 0.1% or less.
1% or less.

When the resin layer is laminated with the transparent film, if necessary, the transparent film and / or the surface on which the resin layer is laminated may be subjected to an electrical treatment such as a corona discharge treatment or a spark treatment, a low pressure or a low pressure treatment. Performs a known surface activation treatment such as a plasma treatment under normal pressure, an ultraviolet irradiation treatment in the presence or absence of ozone, an acid treatment with chromic acid or the like, a flame treatment, and a silane or titanium-based primer treatment. Thereby, stronger adhesion can be obtained.

The composite film of the present invention has a light transmittance of 85.
%, Preferably 90% or more, and the haze is 2% or less, preferably 1% or less. A preferable photoelastic coefficient has an absolute value of 30 × 10 ⁻¹³ cm ² / dyn or less, and more preferably 10 × 10 ⁻¹³ cm ² / dy.
n or less, more preferably 5 × 10 ⁻¹³ cm ² / d
yn or less. If the photoelastic coefficient is larger than this, when used as a polarizer protective film, a contraction stress of the polarizer tends to cause a phase difference to occur, which may undesirably lower the optical characteristics of the polarizing film. The retardation of the transparent composite film is preferably less than 10 nm, more preferably less than 5 nm, and even more preferably less than 3 nm. Further, the retardation in the film thickness direction of the transparent composite film is also important for improving the viewing angle characteristics of the obtained polarizing film. The phase difference in the thickness direction is preferably 50 nm or less, more preferably 30 nm or less, and still more preferably 10 nm or less.

In another embodiment of the present invention, the transparent composite film preferably has a retardation of 10 nm or more and 1000 nm or less.

The transparent composite film contains a small amount of a plasticizer, a heat stabilizer, an ultraviolet absorber, a processability improver such as a lubricant, a known additive such as a filler, and other polymers, if necessary. You can do it. These additives can be added to either the transparent film and / or the resin layer.

Examples of preferred plasticizers include phthalic acid plasticizers such as dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate, di-n-ethylhexyl phthalate, Diisooctyl phthalate, di-n-octyl phthalate, di-n-phthalate
-Decyl, diisodecyl phthalate, di-n-dodecyl phthalate, diisotridecyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, di-2-phthalate
Ethylhexyl, di-2-ethylhexyl isophthalate, and aliphatic dibasic acid-based plasticizers include di-adipate
n-decyl, diisodecyl adipate, di-adipate
2-ethylhexyl, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, phosphate plasticizers such as tributyl phosphate, tri-2-ethylhexyl phosphate,
2-ethylhexyl, tricresyl phosphate, epoxidized soybean oil, epoxidized tall oil fatty acid-2-ethylhexyl as an epoxy plasticizer, butyl stearate, butyl oleate, chlorinated paraffin as a fatty acid ester plasticizer, Chlorinated fatty acid methyl, polymer additives such as polyethylene glycol dimethyl ether, polyethylene glycol benzoate, and polymer compounds containing an ester group (eg, dibasic acids such as adipic acid, sebacic acid, and phthalic acid; Polycondensates such as propylene glycol and 1,3-propylene glycol). Among these additives, di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2 sebacate, which do not contain an aromatic group. -Ethylhexyl, tributyl phosphate, tri-2-ethylhexyl phosphate, 2-phosphate
Ethylhexyl, tricresyl phosphate, epoxidized soybean oil, epoxidized tall oil fatty acid-2-ethylhexyl, butyl stearate, butyl oleate, chlorinated paraffin, chlorinated fatty acid methyl, polyethylene glycol dimethyl ether, or a polymer containing an ester group Plasticizers such as compounds (dibasic acids such as adipic acid and sebacic acid and polycondensates such as 1,2-propylene glycol and 1,3-propylene glycol) are preferable because they do not deteriorate the retardation of the obtained film. . These plasticizers are added in an amount of 20 parts by weight or less based on 100 parts by weight of the film. If the amount exceeds 20 parts by weight, the mechanical properties and heat resistance of the film are unnecessarily reduced, which is not preferable.

Further, a filler may be contained for the purpose of improving the slipperiness of the film. As the filler, inorganic or organic fine particles can be used. Examples of inorganic fine particles include silicon oxide, titanium dioxide, aluminum oxide, metal oxide fine particles such as zirconium oxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silicate fine particles such as magnesium silicate,
Calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, and the like can be used. As the organic fine particles, resin fine particles such as polymethacrylic acid ester type, polyacrylic acid ester type, polyolefin type, polystyrene type, divinylbenzene type, benzoguanamine type and organic silicone type can be used.

By including an ultraviolet absorber in the transparent composite film, the weather resistance of the film of the present invention can be improved, and the durability of a polarizing film or a liquid crystal display device using the film of the present invention can be improved, which is practically preferable. . As the ultraviolet absorber, 2- (2H-benzotriazole-
Benzotriazole-based ultraviolet absorbers such as 2-yl) -p-cresol and 2-benzotriazol-2-yl-4,6-di-t-butylphenol; 2- (4,6-diphenyl-1,3,5) -Triazin-2-yl) -5
Examples include triazine-based ultraviolet absorbers such as [(hexyl) oxy] -phenol, and benzophenone-based ultraviolet absorbers such as octabenzone. Also, 2,4-di-t-butylphenyl-3,5-di-t- Light stabilizers such as benzoate light stabilizers such as butyl-4-hydroxybenzoate and hindered amine light stabilizers such as bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate can also be used. In particular, an ultraviolet absorber mainly composed of a benzotriazole-based compound having a small volatile content at a high temperature is preferable because contamination of the film surface and the apparatus can be prevented by volatilization and dissipation due to heating at the time of forming the film.

The transparent composite film of the present invention has improved adhesiveness to an adhesive when a cycloolefin resin, a polystyrene resin, or an imide resin is used as the transparent film. A highly reliable polarizing film can be obtained by bonding the polarizer with an adhesive.
As the adhesive that can be used, known adhesives can be used, and polyvinyl alcohol, polyvinyl alcohol-based adhesives such as polyvinyl butyral, and polyacryl-based such as butyl acrylate, polyurethane-based, and polyester-based adhesives can be used. Can be used.
These adhesives are used after being dissolved and dispersed in a solvent or water.

Further, the resin layer surface of the composite film is
Electrical treatment such as corona discharge treatment and spark treatment, plasma treatment under low pressure or normal pressure, ultraviolet irradiation treatment in the presence or absence of ozone, acid treatment with chromic acid, flame treatment, silane-based or titanium-based By performing a known surface activation treatment such as a primer treatment, stronger adhesion can be obtained. The degree of a typical corona discharge treatment as a surface treatment can be controlled by the discharge amount represented by the following formula (II).

H = P / (LS × M) (II) where H is the amount of discharge, P is high-frequency power (W), LS is the film passing speed (m / min), and M is the discharge width (m). It is. Preferred conditions for the corona discharge treatment are 10 to
500 W · min / m ² . Considering productivity,
A more preferable upper limit of the discharge amount is 300 W · min / m ^2.
And more preferably 100 W · min / m ² . A preferable plasma treatment is a normal pressure plasma treatment in a single or mixed gas of hydrogen, carbon dioxide, nitrogen, argon, helium, oxygen, or the like as an atmosphere gas. Generally, as an atmosphere gas, 1% to 20% of one or more active gases such as oxygen, air, and carbon dioxide are contained in an inert gas such as nitrogen, helium, or argon.
It is preferable to use them in a mixture by volume%.

Further, when a hydrolyzable resin is used as the resin layer, the transparent composite film of the present invention is subjected to the same saponification treatment as that of the known triacetyl cellulose, so that the polyvinyl alcohol-based adhesive can be used as it is. Can also obtain extremely strong adhesion to the polarizer. Examples of the hydrolyzable resin forming the resin layer include cellulose diacetate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose ester resins such as cellulose acetate propionate, methyl cellulose, ethyl cellulose, and alkyl cellulose such as ethyl hydroxyethyl cellulose. Ether-based resin,
Carboxymethyl cellulose, hydroxyethyl cellulose, cellulose ether resins such as hydroxypropyl cellulose, nitrocellulose resins, or derivatives of these cellulose resins, polyvinyl ester resins such as polyvinyl acetate and polyvinyl propionate, and saponified products thereof, Olefins of olefins such as ethylene and propylene with vinyl esters such as vinyl acetate and vinyl propionate-vinyl ester resins and saponified products thereof, isobutylene-maleic anhydride resins and hydrolyzed products thereof, alkali metal salts, polyacrylic acid and polyacrylic acid Methacrylic acid resins and their copolymers with methacrylic acid methyl ester and acrylic acid methyl ester can be suitably used. In particular, a cellulosic resin is a preferable resin because it has relatively high heat resistance, and it is easy to obtain a resin having a wide range of solubility parameters, and the saponified layer on the surface of the resin layer has excellent water resistance.

The saponification treatment can be performed under the same conditions as for cellulose triacetate. As a saponifying agent, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an organic ammonium hydroxide salt such as tetramethylammonium hydroxide can be used, and a surfactant is added as necessary. can do. Organic ammonium water such as tetraalkylammonium hydroxides such as tetramethylammonium hydroxide and hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide, which are known as organic alkalis as alkali components. Oxides can also be used as a suitable alkali. These organic alkalis are used as an aqueous solution or a mixed solution of water and methyl alcohol, and if necessary, a nonionic surfactant such as polyethylene glycol can be used in combination. Saponification can be performed by immersing the composite film in an aqueous solution in which the above-mentioned saponifying agent is dissolved, or a mixed solution of alcohol / water under heating. Preferred saponification times are from 10 seconds to 10 minutes,
Preferred saponification bath temperatures are from room temperature to 80 ° C. The transparent composite film of the present invention that has been subjected to the saponification treatment, after washing with water, is easily formed with a polarizer using a polyvinyl alcohol-based adhesive,
And it can adhere firmly.

By performing such a surface activation treatment or a saponification treatment, the surface energy is usually reduced to 50 d or less.
yne / cm or more and 80 dyne / cm or less, more preferably 55 dyne / cm or more and 75 dyne / cm.
Or less, more preferably 60 dyne / cm or more and 72 dy
Ne / cm or less, and stable surface energy can be obtained over a long period of time. In particular, in the case of the saponification treatment, it is possible to obtain a surface having a surface energy of 65 dyne / cm or more and extremely high affinity with the aqueous adhesive.
The surface energy of the film can be measured by a known method. For details, see D.S. K. Owens, Jo
urnal of Applied Polymer
Science, vol. 13, p. 1741 (1969)
Year). Further, the pure water contact angle is preferably 60 ° or less, more preferably 40 ° or less, and further preferably 30 ° or less.

Further, a coating layer such as a hard coat layer can be formed on the surface of the transparent composite film of the present invention which is not adhered to the polarizer, if necessary. Further, the film of the present invention, via the coating layer, or,
Without intervening, a transparent conductive layer of indium tin oxide or the like can be formed by a sputtering method or the like and used as an electrode substrate of a plastic liquid crystal display device or an electrode substrate of a touch panel, or an antireflection layer can be formed.

The coating layer has a thickness of 0.1 μm to 1 μm.
It is preferable that the thickness is formed in the range of 0 μm, preferably 1 μm to 5 μm.

Preferred examples of the coating layer include organic coating layers of melamine resin type, acrylic resin type, urethane resin type, alkyd resin type and fluorine-containing resin type, and organic-silicone composite type. Examples include polyester polyols and etherified methylol melamine mixed with partial hydrolysis products of alkyl trialkoxysilane and tetraalkoxysilane. Further, silicone-based materials such as partial hydrolysates of aminosilane and epoxysilane, partial hydrolysates of silane coupling agents and alkyltrialkoxysilanes / tetraalkoxysilanes, and hydrolysates of colloidal silica and alkyltrialkoxysilanes are also suitable. Can be used.

After coating these coating materials on the surface of the transparent composite film of the present invention, a film having a solvent-resistant film can be obtained by thermosetting. At this time,
Simultaneous use of a low-temperature curing type catalyst is a preferred method for suppressing undesirable thermal denaturation of the film. A cured layer obtained by adding a photosensitizer to a monomer or oligomer such as a polyfunctional acrylate and using ultraviolet rays or an electron beam can also be suitably used. Various fillers can be added to the coating layer as needed. By adding a filler, glare due to film surface reflection can be prevented, and the occurrence of Newton rings due to optical interference when another film is laminated can be prevented. Preferred fillers include organic fillers such as polymethacrylic acid esters, polyacrylic acid esters, polyolefins, polystyrenes, divinylbenzenes, benzoguanamines, and organic silicones, and inorganic fillers such as silica, alumina, and titanium oxide. Can be used. On the other hand, when the filler is used for a display portion such as a liquid crystal display device by adding a filler, a glaring feeling of a display image may be given, and JIS K71
It is desirable that the transmitted image clarity measured by using the optical comb of 0.125 mm by the method described in 6.6 of JP-A No. 05 to be 80% or more.

A preferred use of the transparent composite film of the present invention is an optically isotropic film, and another preferred use is a retardation film. The optically isotropic film is further applied to various uses. One such preferred use is
It is a polarizer protective film, and another preferable application is an electrode substrate of a plastic liquid crystal display device or a resistive touch panel. Another preferred application is a support film for a recording medium or a protective film for a recording layer. Details of these are described in Nikkei Micro Device (published by Nikkei Inc.), July 17, 2000, page 155.

When the transparent composite film of the present invention is used as a protective film for a polarizer, the composite film of the present invention which has been subjected to a surface activation treatment or a saponification treatment has an adhesion strength with a polyvinyl alcohol-based adhesive of 50 kg / cm. ² or more,
Preferably, it can be 200 kg / cm ² or more.

[0079]

EXAMPLES The methods for measuring the physical properties shown in Examples and Comparative Examples are described below.

<Glass transition temperature> JIS K7121
Compliant with Seiko Electronics' differential scanning calorimeter (DSC)
It measured using. That is, 10 mg of a sample was set in a DSC device, and the temperature of the sample was raised from room temperature at 10 ° C./min, and the glass transition temperature was measured.

<Light Transmittance> JIS K7105-1
The measurement was performed using light of 550 nm according to the method described in 5.5 of 981.

<Haze> JIS K7105-198
The measurement was performed according to the method described in 6.4 of 1).

<Phase Difference> Using a microscopic polarization spectrophotometer (Oak Seisakusho: TFM-120AFT), the measurement wavelength was 51
It was measured at 4.5 nm.

<Phase Difference in Thickness Direction> Using a microscopic polarization spectrophotometer (Oak Manufacturing Co., Ltd .: TFM-120AFT),
The angle dependence of the phase difference is measured at a measurement wavelength of 14.5 nm, and nx, ny, and nz are determined. The thickness of the film is separately measured, and the retardation in the thickness direction is calculated using the following equation. Phase difference in thickness direction = | (nx + ny) / 2−nz | × d

<Water-Soluble Content> A film having a thickness of 50 μm is dried at 50 ° C. for 24 hours, and the film weight W1 is measured. This film is immersed in water at 40 ° C. for 30 minutes, then dried at 50 ° C. for 24 hours, and the film weight W2 is measured. Calculate the water soluble fraction from the following formula. Water soluble fraction (%) = (W1-W2) / W1 × 100

<Water absorption> A film having a thickness of 50 μm was dried at 50 ° C. for 24 hours and then cooled to obtain a film weight W
Measure d. After immersing this film in water at 23 ° C. for 24 hours, the moisture adhering to the surface is wiped off and the weight Ww
Is measured. Calculate the water absorption from the following formula. Water absorption (%) = (Ww−Wd) / Wd × 100

<Photoelastic coefficient> The birefringence of the film was measured using a microscopic polarization spectrophotometer (TFM-120AFT manufactured by Oak Manufacturing Co., Ltd.).
-PC). One of the films cut into strips having a width of 1 cm in the optical axis direction was fixed, and 50 g of 10 g
A weight of 0 g or 150 g is applied, and the amount of change in birefringence due to unit stress is calculated.

<Tear Propagation Strength> JIS K7128 (Trouser method) using an autograph manufactured by Shimadzu Corporation
It measured according to. The measurement was performed at a tensile speed of 200 mm / min, and a film having an average thickness of 50 ± 5 μm was used.

<Mass Fatigue Resistance> MI manufactured by Toyo Seiki Seisaku-sho, Ltd.
T rubbing fatigue tester (FOLDINGENDURANCE)
TESTER) type D was measured according to JIS C5016. In addition, the measurement is 15 mm in width and 20 in length.
A sample having a shape of 0 mm and an average thickness of 50 ± 5 μm was used.

<Moisture Permeability of Polymer Film> JIS Z0
The measurement was carried out according to the method described in No. 208.

Hereinafter, the present invention will be described in detail with reference to examples.

Reference Example 1 100 parts by weight of an alternating copolymer composed of isobutene and N-methylmaleimide (N-methylmaleimide content: 50 mol%, glass transition temperature: 157 ° C.), and acrylonitrile content: 28% by weight. 60 parts by weight (37.5% by weight) of an acrylonitrile / styrene copolymer is dissolved in a methylene chloride solution to a solid concentration of 15% by weight, and the solution is poured on a biaxially stretched polyethylene terephthalate film spread on a glass plate. It was extended and left at room temperature for 60 minutes. Thereafter, the film was peeled off, and sandwiched between four-side fixing jigs.
Drying was performed at 60 ° C. for 30 minutes to obtain a film. The thickness of the film is 120 μm, the retardation in the film plane direction of the film is 2 nm, and the retardation in the thickness direction is 3n.
m, the light transmittance was 92%, and the haze was 0.3%.
In addition, the glass transition temperature was 141 ° C., the rub fatigue resistance was 5 times in the MD direction, 6 times in the TD direction, and the tear propagation strength was 79 gf / mm in the MD direction and 76 gf / mm in the TD direction.
This film was stretched 1.8 times at 155 ° C. in the MD direction, and then stretched 1.8 times at 155 ° C. in the TD direction. This film has a thickness of 49 μm, a haze of 0.4%, a phase difference in the plane direction of the film of 1 nm, and a phase difference of 4 in the thickness direction.
and the fatigue resistance was 161 times in the MD direction, 138 times in the TD direction, and the tear propagation strength was 214 gf / MD in the MD direction.
mm and TD direction were 152 gf / mm. The solubility parameter calculated from the composition of the film is 23.5
MPa was ^0.5 .

Reference Example 2 A polyvinyl alcohol film (vinylon film, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a thickness of 75 μm was stretched uniaxially four times, and 0.075% by weight of iodine was maintained while maintaining the tension. Immersed in an aqueous solution containing 5% by weight of potassium iodide at room temperature for 1 minute. Furthermore,
A polarizer was obtained by dipping in an aqueous solution containing 7.5% by weight of boric acid and 6% by weight of potassium iodide at 70 ° C. for 5 minutes to perform a crosslinking treatment.

Example 1 Using a mixed solution of methyl ethyl ketone / toluene (50/50% by weight) containing 10% by weight of cellulose acetate propionate (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.7). The coating was performed on the transparent film obtained in Reference Example 1 using a wire bar. The obtained film was dried at 100 ° C. for 1 minute to obtain a transparent composite film having a 1 μm resin layer on one side. The in-plane retardation of this film is 2n
m, the phase difference in the thickness direction is 3 nm, the light transmittance is 92%,
Haze was 0.5%. The water absorption of the cellulose acetate propionate used was 1.6%, and the water-soluble content was 1% or less. The solubility parameter of the cellulose acetate propionate used was 22.5.
Mpa was ^0.5 , and the absolute value of the difference between the solubility parameter and the transparent film was 1.0 Mpa ^0.5 . Further, the moisture permeability of the resulting film, 85 g / in 40 ° C. -90% RH (m ² · 24hr), in 70 ° C. -90% RH was ^{365g / (m 2 · 24hr)} .

The transparent composite film was immersed in a 10% aqueous sodium hydroxide solution at 50 ° C. for 3 minutes to perform a saponification treatment, followed by washing with water and drying. The surface of the film resin layer before the treatment has a contact angle of pure water of 66 ° and a surface energy of 48 dyn.
e / cm, and the pure water contact angle on the surface opposite to the resin layer (the surface on which the resin layer was not provided) was 70 °. After processing,
The resin layer surface is 21 ° and 69 dyne / cm, respectively.
The surface on the opposite side to the resin layer had a pure water contact angle of 70 °, which was the same as before the treatment. This film has a pure water contact angle of 23 ° on the resin layer side and a surface energy of 68 dyne /
cm and a stable surface energy.

After the surfaces to be treated are opposed to each other and laminated via an aqueous solution of a PVA-based adhesive and closely adhered by a rolling roll,
After drying for minutes, the films were adhered to each other. When a T-type peel test was performed to measure the adhesive strength, the film was torn and could not be peeled.

Further, on both surfaces of the polarizer of Reference Example 2, a surface-treated transparent composite film was laminated via an aqueous solution of a PVA-based adhesive with the surface-treated surface facing the polarizer, and was brought into close contact with a rolling roll. Thereafter, the film was dried at 70 ° C. for 5 minutes to obtain a polarizing film. When the adhesive strength between the transparent composite film and the polarizer was measured by a T-peel test, the film could not be measured for tearing. Further, as a result of observing the state of the polarizing film after being left for 500 hours in an environment of 60 ° C. and 90% relative humidity, no color change or color omission was observed, and no floating or peeling of the film was observed.

Comparative Example 1 In the same manner as in Example 1, 6 of cellulose diacetate (degree of acetyl group substitution: 2.0) was prepared.
A resin layer having a thickness of 1 μm was formed using a weight-% ethyl acetate solution, and the resin layer was similarly saponified with an alkali. When the treated surfaces were opposed to each other and bonded with a PVA-based adhesive to measure the peel strength, they were easily peeled at the interface between the cellulose diacetate and the transparent film. The solubility parameter of cellulose diacetate is 26.8 MPa ^0.5 ,
The absolute value of the difference from the solubility parameter of the transparent film used was 3.3 MPa ^0.5 .

Comparative Example 2 A resin layer having a thickness of 1 μm was formed using a mixed solution of water / methyl ethyl ketone (50/50% by volume) containing 9% by weight of polyvinyl alcohol (degree of saponification: 90%). 70 ° C. in the same manner as in Example 1.
After drying for -5 minutes, a laminated film was obtained. The film could be easily peeled off, and the adhesive surface after the peeling had a tack remaining, and the adhesive was insufficiently dried. 70 ℃ -5
When the peeling test was performed on the film dried at 80 ° C. for 30 minutes with the film dried as it was, the film could be easily peeled. The release surface was dry and the adhesive was dry. The solubility parameter of the polyvinyl alcohol used was 37.3 MPa ^0.5 , and the absolute value of the difference was 14.8 MPa ^0.5 . When the water-soluble component was measured, the soluble component was 90% or more.

Example 2 A glutarimide copolymer comprising N-methylglutarimide and methyl methacrylate (N-methylglutarimide content: 75% by weight, acid content: 0.01 meq / g or less, glass transition temperature: 147 ° C.) )
65% by weight and 35% by weight of a copolymer composed of styrene and acrylonitrile having acrylonitrile and styrene contents of 28% by weight and 72% by weight, respectively, were dissolved in methylene chloride so as to have a solid concentration of 15% by weight. It was cast on a biaxially stretched PET film spread on a glass plate and left at room temperature for 60 minutes. Thereafter, the film was peeled off, and sandwiched between four pieces of fixing jigs.
After drying for 0 minutes, a film having a thickness of 100 μm was obtained.
The glass transition temperature of this film was 140 ° C., and the photoelastic coefficient was 6 × 10 −13 cm ² / dyn. A 30 cm x 10 cm sample film was cut out of this film, and a stretching test device (Toyo Seiki Seisakusho, X4HD-
After stretching 1.5 times at 160 ° C. in the MD direction using HT), the film was stretched 1.5 times at 160 ° C. in the TD direction. The thickness of this film is 45 μm, the haze is 0.4%, the in-plane retardation of the film is 2 nm, the retardation in the thickness direction is 4 nm, and the anti-rubbing fatigue is 210 times in the TD direction and 190 in the MD direction.
Times, the tear strength is 161 gf / mm in MD direction, T
The direction D was 158 gf / mm. The solubility parameter of the resulting film was 23.2 MPa ^0.5 . The moisture permeability of the obtained film is 40 ° C.-90.
% Relative humidity: 43 g / (m ² · 24 hr), 70 ° C.-
At 90% relative humidity, it was 182 g / (m ² · 24 hr).

In the same manner as in Example 1, 1 μm of cellulose acetate propionate was applied to one surface of the transparent film.
m was formed and a surface treatment was performed. When the obtained film was bonded with a PVA-based adhesive and the peel strength was measured, the film could not be measured for tearing. Solubility parameter of cellulose acetate propionate is 22.5 MPa ^0.5, the absolute value of the difference was 0.7 MPa ^0.5.

(Comparative Example 3) Using the film of Example 2,
In the same manner as in Comparative Example 1, a 1 μm resin layer made of cellulose diacetate was formed and, after surface treatment, bonded using a PVA-based adhesive and the adhesive strength was measured, but the film was easily peeled. . The absolute value of the difference between the two solubility parameters was 3.6 MPa ^0.5 .

(Example 3) This was used in Reference Example 1. Using 65 parts by weight of an alternating copolymer consisting of isobutene and N-methylmaleimide and 35 parts by weight of a styrene-acrylonitrile copolymer having an acrylonitrile content of 28% by weight,
The resin composition obtained by melt kneading was formed into a melt extruded film using a T-die extruder (cylinder diameter 40 mm, L / D24) to obtain a raw film having a thickness of about 100 μm. This film was stretched 1.5 times at 160 ° C. in the MD direction and then 1.5 times at 160 ° C. in the TD direction. The thickness of the obtained film is 50 μm, the haze is 0.4%,
The in-plane retardation of the film is 1 nm, and the retardation in the thickness direction is 4
nm, rubbing fatigue resistance was 161 times in the MD direction and 13 in the TD direction.
Three times, the tear propagation strength was 151 gf / mm in the MD direction,
The TD direction was 148 gf / mm. The moisture permeability is 85 g / (m ² · 24 at 40 ° C.-90% relative humidity.
hr), 365 g / (m ² ) at 70 ° C. and 90% relative humidity.
24 hr).

The obtained film was subjected to a surface treatment by forming a cellulose acetate propionate layer in the same manner as in Example 1, and then bonded with a PVA-based adhesive to evaluate the bonding strength. It could not be measured.

(Example 4) Glutar used in Example 2
65% by weight of imide resin and styrene-acrylonitrile
35% by weight of the polymer was melt-kneaded into pellets. this
The pellets are fed to a T-die melt extruder and the thickness is 1
A 35 μm film was obtained. Glass transition of this film
The temperature is 137 ° C. and the photoelastic coefficient of the film is 6 × 1
0^-13cm ^Two / Dyne. This film, M
After stretching 1.7 times at 160 ° C. in the D direction,
The film was stretched 1.8 times at 160 ° C. The thickness of the obtained film
Is 55 μm, haze is 0.4%, in-plane retardation of film
Is 1 nm, and the retardation in the thickness direction is 3 nm.
Means TD direction 190 times, MD direction 215 times, tear
The strength was 171 gf / mm in the MD direction and 17 in the TD direction.
It was 3 gf / mm. Also, the moisture permeability of the obtained film
The degree is 43 g / (m^Two・ 2
4 hr), 182 g / (m
^Two24 hr).

In the same manner as in Example 1, 1 μm of cellulose acetate propionate was applied to one surface of the transparent film.
m was formed and a surface treatment was performed. The surface of the film resin layer before the treatment had a contact angle of pure water of 66 °, a surface energy of 48 dyne / cm, and a contact angle of pure water on the surface opposite to the resin layer (surface on which no resin layer was provided) of 72 °. . After the treatment, the surface of the resin layer is 21 ° and 69 °, respectively.
Although the surface energy was extremely small as dyne / cm, the surface opposite to the resin layer had a pure water contact angle of 72 °, which was the same as before the treatment. This film showed a stable surface energy with a contact angle of pure water on the resin layer side of 23 ° and a surface energy of 68 dyne / cm even after a lapse of one month.

The obtained surface-treated film was prepared in the same manner as in Example 1.
Similarly, adhere with PVA-based adhesive and measure peel strength.
Is it impossible to measure the tearing of the film
Was. The solubility parameter of cellulose acetate propionate
The parameter is 22.5MPa ^0.5And the absolute difference
The value is 0.7MPa^0.5Met.

Example 5 In the same manner as in Reference Example 1, an alternating copolymer 1 comprising isobutene and N-methylmaleimide
00 parts by weight and an acrylonitrile-styrene copolymer 2
5 parts by weight (20% by weight) is dissolved in a methylene chloride solution to a solid concentration of 15% by weight, cast on a biaxially stretched polyethylene terephthalate film spread on a glass plate, dried, and dried to a thickness of 100 μm. A film was obtained. This film was stretched 1.8 times at 145 ° C. in the MD direction to obtain a retardation film having a retardation value of 142 nm. The solubility parameter calculated from the composition of this film is 23.4MP
a was ^0.5 . On one surface of this film, a 1 μm-thick cellulose acetate propionate resin layer was formed in the same manner as in Example 1 to obtain a transparent composite film. The retardation in the thickness direction of this film was 145 nm, the light transmittance was 92%, and the haze was 0.5%. The solubility parameter of cellulose acetate propionate is 22.
Is 5 MPa ^0.5, the absolute value of the difference between the solubility parameter of the transparent film was 0.9 MPa ^0.5. Also,
The moisture permeability of the obtained film was 380 g / (m ² · 24 hr) at 70 ° C.-90% relative humidity. Further, the pure water contact angle and the surface energy of the saponified resin layer surface showed an extremely large surface energy of 20 ° and 69 dyne / cm, but the pure water contact angle of the surface opposite to the resin layer was reduced. 70 °, which was the same as before the treatment. The treated surfaces were opposed to each other, laminated via an aqueous solution of a PVA-based adhesive, brought into close contact with a roll, and dried at 70 ° C. for 5 minutes to bond the films together. When a T-type peel test was performed to measure the adhesive strength, the film was torn and could not be peeled.

[0109]

The transparent composite film of the present invention has a resin layer having a specific solubility parameter on its surface.
A film having good adhesion to the resin layer and, if necessary, surface-treating the resin layer as needed can provide a film having significantly improved adhesion to an adhesive.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/02 C08L 101/02 G02B 5/30 G02B 5/30 G02F 1/1335 510 G02F 1/1335 510 ( 72) Inventor Sadao Fujii 8-4-9 Chikushigaoka, Kita-ku, Kobe City, Hyogo Prefecture AK01B AK01C AK03A AK03B AK03C AK12A AK12B AK12C AK27A AK27B AK27C AL01A AL01B AL01C BA02 BA03 BA10B BA10C BA26 EH46 EH462 EJ86 EJ862 GB41 JB16A JB16B JB16C JL01 JN01A JN01B JN01C JN06 JN10 YY00A YY00B YY00C 4J002 AA07W AA07X BC06X BG12W BH02W GP00

Claims (12)

[Claims] 1. The method according to claim 1, wherein at least one surface of the transparent film has
A transparent composite film having a composition different from that of the film and having a resin layer having an absolute value of a difference in solubility parameter from the film of 2.0 MPa ^0.5 or less. 2. The transparent composite film according to claim 1, wherein the light transmittance is 85% or more, the haze is 2% or less, and the retardation value is 10 nm or more and 1000 nm or less. 3. The transparent composite film according to claim 1, wherein the light transmittance is 85% or more, the haze is 2% or less, and the retardation value is less than 10 nm. 4. The resin layer according to claim 1, wherein said resin layer contains a compound capable of producing at least one functional group selected from a hydroxyl group, an amino group and a carboxyl group by hydrolysis with an acid or an alkali. 3. The transparent composite film according to 3. 5. A transparent film comprising: (A) a thermoplastic resin A comprising at least a component having a substituted or unsubstituted imide group in a side chain; and (B) a phenyl group and a nitrile having at least a substituted or unsubstituted phenyl group in a side chain. The transparent composite film according to claim 1, further comprising a thermoplastic resin B having a group. 6. The transparent composite film according to claim 5, wherein the thermoplastic resin A comprises an olefin component and a component having a substituted or unsubstituted imide group in a side chain. 7. The thermoplastic resin A contains a maleimide unit represented by the formula (1), and its content is from 30 mol% to 8 mol%.
7. The transparent composite film according to claim 5, wherein the amount is 0 mol%. Embedded image (Here, R ¹ represents hydrogen or an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms.) 8. The thermoplastic resin A contains a glutarimide unit represented by the formula (2), and its content is 20% by weight.
6. The transparent composite film according to claim 5, wherein Embedded image (Wherein, R ² , R ³ , and R ⁴ independently represent hydrogen or an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms;
Shows a cycloalkyl group and an aryl group. ) 9. The thermoplastic resin B comprises a substituted or unsubstituted acrylonitrile component and a substituted or unsubstituted styrene component, and the substituted or unsubstituted acrylonitrile component in the thermoplastic resin B is 20% by weight to 50% by weight;
9. The transparent composite film according to claim 5, wherein the substituted or unsubstituted styrene component is 50 to 80% by weight. 10. A polarizer protective film comprising the transparent composite film according to claim 1. 11. A polarizing film comprising the polarizer protective film according to claim 10. 12. A liquid crystal display device using the polarizing film according to claim 11.