WO2019182146A1

WO2019182146A1 - Active energy ray-curable resin composition, polarizing film protective layer, and polarizing plate

Info

Publication number: WO2019182146A1
Application number: PCT/JP2019/012235
Authority: WO
Inventors: 友樹木田; 拓石井; 卓也畠山; ▲高▼木　誠司
Original assignee: 三菱ケミカル株式会社
Priority date: 2018-03-22
Filing date: 2019-03-22
Publication date: 2019-09-26
Also published as: CN111886525A; CN111886525B; KR20200135339A

Abstract

The present invention relates to an active energy ray-curable resin composition for polarizing film protection. The present invention also relates to a polarizing film protective layer, which is obtained by curing the active energy ray-curable resin composition. The present invention also relates to a polarizing plate which comprises the polarizing film protective layer. A polarizing plate according to the present invention exhibits excellent wet heat resistance.

Description

Active energy ray-curable resin composition, polarizing film protective layer and polarizing plate

The present invention relates to an active energy ray-curable resin composition, a polarizing film protective layer, and a polarizing plate. More specifically, the present invention relates to an active energy ray-curable resin composition suitable for a protective layer for a polarizing film constituting a polarizing plate used in a liquid crystal display device or the like.

Liquid crystal display devices are widely used as image display devices for liquid crystal televisions, computer displays, mobile phones, digital cameras, and the like. Such a liquid crystal display device has a configuration in which polarizing plates are laminated on both sides of a glass substrate in which liquid crystal is sealed, and various optical functional films such as a retardation plate are laminated thereon as necessary.

Conventionally, a polarizing plate has a configuration in which a protective film is bonded to at least one surface, preferably both surfaces, of a polarizing film made of a polyvinyl alcohol film (hereinafter, polyvinyl alcohol may be abbreviated as “PVA”). It has become. Here, as a polarizing film, a dichroic material such as iodine is dispersed and adsorbed in a PVA film formed using a PVA resin having a high saponification degree. A uniaxially stretched PVA film cross-linked with an agent is widely used. Since such a polarizing film is a uniaxially stretched PVA film, it tends to shrink under high humidity. Therefore, a protective film is bonded to the polarizing film for the purpose of supplementing moisture resistance and strength.

As such a protective film, thermoplastic resins such as cellulose resin, polycarbonate resin, cyclic polyolefin resin, (meth) acrylic resin, and polyester resin are transparent, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. In particular, a protective film made of a triacetyl cellulose (TAC) resin has been widely used.

These protective films are bonded to the polarizing film with an adhesive. As such an adhesive, from the viewpoint of adhesion to a polarizing film having a hydrophilic surface, a PVA resin aqueous solution, particularly a PVA resin aqueous solution mainly composed of a high saponification degree PVA resin similar to the polarizing film is preferably used. ing.

By the way, in recent years, there has been a demand for thinner polarizing plates, and an energy beam curable composition is used as a polarizing film without using a triacetyl cellulose (TAC) film that has been most commonly used as a protective film. It has been studied to form a protective film by irradiating energy rays after coating.

For example, Patent Document 1 proposes a polarizing plate that is superior in terms of weight reduction and durability, including a protective film mainly composed of an epoxy resin on at least one surface of a polarizer.

Patent Document 2 proposes a polarizing plate excellent in adhesion and high durability between a polarizer and a protective layer formed of a cured product of a resin composition containing an aromatic epoxy compound on at least one surface thereof. Yes.

Japanese Unexamined Patent Publication No. 2004-245924 Japanese Unexamined Patent Publication No. 2016-85369

However, the protective film described in Patent Document 1 and the protective layer described in Patent Document 2 do not have sufficient performance, and a polarizing plate using them may have insufficient moisture and heat resistance.

Therefore, an object of the present invention is to provide an active energy ray-curable resin composition capable of forming a polarizing film protective layer from which a polarizing plate excellent in moisture and heat resistance can be obtained.

That is, the present invention relates to the following <1> to <11>.
<1> An active energy ray-curable resin composition for protecting a polarizing film, which contains an epoxy resin having an epoxy equivalent of 300 or more.
<2> The active energy ray-curable resin composition according to <1>, wherein the epoxy resin has an aromatic ring or an alicyclic skeleton.
<3> The active energy ray-curable resin composition according to <1> or <2>, which contains an oxetane compound.
<4> The active energy ray-curable resin composition according to <3>, wherein the content ratio of the oxetane compound is 1 to 90 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the oxetane compound. .
<5> An active energy ray-curable resin composition for protecting a polarizing film, comprising a bifunctional or higher functional oxetane compound (A1) and a compound (B) having at least two unsaturated hydrocarbon groups,
An active energy ray-curable resin composition, wherein a content ratio of the oxetane compound (A1) is 51 to 99 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition.
<6> The active energy ray-curable resin composition according to <5>, wherein the compound (B) is a radical polymerizable monomer.
<7> An active energy ray-curable resin composition for protecting a polarizing film comprising a bifunctional or higher functional oxetane compound (A2) and an epoxy compound (C),
The content ratio of the oxetane compound (A2) is 75 to 99 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition,
The active energy ray-curable resin composition, wherein the epoxy compound (C) has at least one of an aromatic ring structure and an alicyclic structure.
<8> The active energy ray-curable resin composition according to any one of <1> to <7>, containing a photoacid generator.
<9> The active energy ray-curable resin composition according to any one of <1> to <8>, comprising a photoradical initiator.
<10> A polarizing film protective layer obtained by curing the active energy ray-curable resin composition according to any one of <1> to <9>.
<11> A polarizing plate having the polarizing film protective layer according to <10>.

When a polarizing film protective layer obtained from the active energy ray-curable resin composition for protecting a polarizing film according to the first embodiment of the present invention is used, a polarizing plate excellent in wet heat resistance can be obtained.

The active energy ray-curable resin composition for protecting a polarizing film according to the second embodiment of the present invention is excellent in curability. The said resin composition can form the polarizing film protective layer excellent in adhesiveness with a polarizing film. When the said polarizing film protective layer is used, the polarizing plate excellent in heat-and-moisture resistance can be obtained.

The active energy ray-curable resin composition for protecting a polarizing film according to the third embodiment of the present invention is excellent in curability. When a polarizing film protective layer obtained from the resin composition is used, a polarizing plate excellent in wet heat resistance can be obtained.

Hereinafter, the present invention will be described in detail, but these show examples of desirable embodiments.

In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

In addition, the active energy ray-curable resin composition for protecting a polarizing film according to the first embodiment of the present invention may be simply referred to as “first resin composition”. The active energy ray-curable resin composition for protecting a polarizing film according to the second embodiment of the present invention may be simply referred to as “second resin composition”. The active energy ray-curable resin composition for protecting a polarizing film according to the third embodiment of the present invention may be simply referred to as “third resin composition”.
The first resin composition, the second resin composition, and the third resin composition may be collectively referred to as “the resin composition of the present invention”.

[First Embodiment]
The first resin composition contains an epoxy resin having an epoxy equivalent of 300 or more.

<Epoxy resin>
The epoxy resin used in the first embodiment of the present invention may have an epoxy equivalent of 300 or more, preferably 500 or more, more preferably 1,000 or more. The epoxy equivalent is usually 10,000 or less, preferably 9,500 or less, more preferably 9,000 or less.

In addition, an epoxy equivalent means the gram number (g / eq) of resin containing an epoxy group of 1 gram equivalent. In the present invention, the epoxy equivalent means an epoxy equivalent measured according to JIS K 7236.

The reason why the polarizing plate having a polarizing film protective layer obtained by curing the first resin composition containing an epoxy resin having an epoxy equivalent of 300 or more is excellent in wet heat resistance is not clear, but is presumed as follows. That is, when the final cured product has a higher molecular weight, the glass transition temperature of the epoxy resin is increased, and the moisture permeability is decreased by decreasing the moisture permeability. As a result, the optical properties of the polarizing plate after the wet heat test are improved. It is presumed that the deterioration of characteristics is suppressed.

Examples of the epoxy resin having an epoxy equivalent of 300 or more include aliphatic epoxy resins, epoxy resins having an aromatic ring, epoxy resins having an alicyclic skeleton, and polymers having an epoxy group.
Especially, the epoxy resin which has 2 or more of epoxy groups is preferable at the point which can improve heat-and-moisture resistance, The epoxy resin which has an aromatic ring, and the epoxy resin which has an alicyclic skeleton are more preferable.

Examples of the aliphatic epoxy resin include higher alcohol glycidyl ether, higher alcohol (EO (ethylene oxide))-modified glycidyl ether, dibromoneopentyl glycol diglycidyl ether, and the like. Moreover, the thing whose epoxy equivalent is 300 or more is mentioned among polyethyleneglycol diglycidyl ether, polypropylene diglycidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, polyglycerin polyglycidyl ether.

Examples of the epoxy resin having an aromatic ring include phenol (EO) -modified glycidyl ether, alkylphenol glycidyl ether, dibromophenyl glycidyl ether, bisphenol type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol novolak type epoxy. Examples of the resin, biphenol type epoxy resin, resorcinol type epoxy resin, hydroquinone type epoxy resin, naphthalene type epoxy resin, and anthracene type epoxy resin having an epoxy equivalent of 300 or more.
Of these, bisphenol type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and bisphenol novolak type epoxy resins are preferable, and bisphenol type epoxy resins are particularly preferable.

Examples of the bisphenol type epoxy resin include a bisphenol A type epoxy resin, a bisphenol E type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, and the like, and an epoxy resin in which these bisphenol structures are mixed may be used.
Of these, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferred because they are easy to handle.

Examples of epoxy resins having an alicyclic skeleton include hydrogenated epoxy resins obtained by hydrogenating aromatic rings of epoxy resins having aromatic rings, (EO) modified alicyclic epoxy resins, and ester modified alicyclic epoxies. Examples thereof include resins.
As the hydrogenated epoxy resin, a hydrogenated bisphenol type epoxy resin is preferable.

Examples of the polymer having an epoxy group include an epoxy group-containing acrylic polymer, an epoxy group-containing acrylic styrene polymer, and an epoxy group-containing polybutadiene polymer.

These epoxy resins can be used alone or in combination.

The content of the epoxy resin in the first resin composition is preferably 10 to 100% by weight, more preferably 20 to 95% by weight, and further preferably 40 to 90% by weight from the viewpoint of heat and moisture resistance.

<Oxetane compound>
The first resin composition preferably contains an oxetane compound because the curability is improved and the heat and moisture resistance is excellent.

The oxetane compound may be a compound having one or more oxetanyl groups in the molecule.
For example, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (cyclohexyloxymethyl) Oxetane compounds having one oxetanyl group in the molecule such as oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl, -3 {[(3-Ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 4,4'-bis [(3- Oxetane having two or more oxetanyl groups in the molecule, such as ethyl-3-oxetanyl) methoxymethyl] biphenyl Compounds and the like.
These oxetane compounds can be used alone or in combination of two or more.

Among these, 3-ethyl-3-hydroxymethyloxetane and 1,4-bis [(3-ethyl-3-oxetanyl) are easily available and have excellent dilutability (low viscosity) and excellent compatibility. ) Methoxymethyl] benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) Methyl, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane and the like are preferably used.

In addition, from the viewpoint of compatibility and adhesiveness, a liquid form is preferred at room temperature (25 ° C.) with a molecular weight of 500 or less, and in addition, since it has excellent curability and durability, it contains two or more oxetanyl groups in the molecule. An oxetane compound containing one oxetanyl group and one (meth) acryloyl group or one epoxy group in the molecule is preferable.

Specifically, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane -3-yl) methyl is preferably used.

Specifically, as the oxetane compound, for example, commercially available Aron Oxetane OXT-101, Aron Oxetane OXT-121, Aron Oxetane OXT-212, Aron Oxetane OXT-221 (all manufactured by Toagosei Co., Ltd.) should be used. Can do. Aron oxetane OXT-101 and Aron oxetane OXT-221 are particularly preferable.

The content of the oxetane compound is preferably 1 to 90 parts by weight, more preferably 5 to 80 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the oxetane compound. More preferably, it is ˜60 parts by weight. If the content is too small, the curability tends to be inferior, and if it is too large, the adhesiveness to the polarizing film tends to decrease.

<Solvent>
The first resin composition can further contain a solvent.
When the first resin composition contains a solvent, the viscosity of the first resin composition can be adjusted, coating properties can be improved, and a polarizing film protective layer having a uniform thickness can be obtained. Improves moist heat resistance.
The viscosity of the first resin composition is preferably adjusted to be 20,000 mPa or less.

Examples of the solvent include toluene, xylene, ethyl acetate, methyl ethyl ketone, alcohols (methanol, ethanol, butanol, propanol, isopropanol, etc.), and toluene, ethyl acetate, and methyl ethyl ketone are preferably used.

The content of the solvent in the first resin composition is preferably 50 to 300 parts by weight and more preferably 70 to 250 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the oxetane compound. The amount is preferably 90 to 200 parts by weight.

If the content of the solvent is too small, the viscosity during coating tends to be high, and a polarizing film protective layer with a uniform thickness tends to be difficult to obtain. If it is too large, the drying time for removing the solvent tends to be long. .

<Epoxy resin having an epoxy equivalent of less than 300>
In addition to the above components, the first resin composition is an epoxy resin having an epoxy equivalent of less than 300, the following aliphatic epoxy resins, alicyclic epoxy resins having an epoxy group on the alicyclic skeleton, An epoxy resin having an aromatic ring can be contained.

(Aliphatic epoxy resin)
Examples of the aliphatic epoxy resin include one epoxy group in the molecule such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidol, alcohol glycidyl ether having 11 to 15 carbon atoms, lauryl alcohol glycidyl ether, and the like. Individual aliphatic epoxy resins, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, Ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl Ether, glycerine polyglycidyl molecule epoxy groups in such ether bifunctional or more having two or more aliphatic epoxy resins. Examples of the polyethylene glycol diglycidyl ether, polypropylene diglycidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, and polyglycerin polyglycidyl ether include those having an epoxy equivalent of less than 300.
These aliphatic epoxy resins can be used alone or in combination of two or more.

The content of the aliphatic epoxy resin in the first resin composition is preferably 40% by weight or less.

(Alicyclic epoxy resin having epoxy group on alicyclic skeleton)
Examples of the alicyclic epoxy resins include 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone modified 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2-epoxy-4-vinylcyclohexane, limonene dioxide and the like. These alicyclic epoxy resins can be used alone or in combination of two or more.

The content of the alicyclic epoxy resin in the first resin composition is preferably 40% by weight or less.

(Epoxy resin with aromatic ring)
The first resin composition can further contain an epoxy resin having an aromatic ring.

Examples of the epoxy resin having an aromatic ring include phenyl glycidyl ether. Also, phenol (EO) modified glycidyl ether, alkylphenol glycidyl ether dibromophenyl glycidyl ether, bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol novolac type epoxy resin, biphenol type epoxy resin, resorcinol type epoxy resin , Hydroquinone type epoxy resin, naphthalene type epoxy resin and anthracene type epoxy resin having an epoxy equivalent of less than 300.

The content of the epoxy resin having an aromatic ring in the first resin composition is preferably 40% by weight or less.

[Second Embodiment]
The second resin composition contains a bifunctional or higher oxetane compound (A1) and a compound (B) having at least two unsaturated hydrocarbon groups.

Usually, when an oxetane compound is blended in a curable resin composition, it is blended so that it is not a main component but a small amount. The reason is that when the oxetane compound is the main component, the glass transition temperature is lowered due to the skeleton of the oxetane compound, and as a result, the heat and humidity resistance tends to be lowered.

However, by increasing the oxetane compound content ratio as described below, combining it with a compound having at least two unsaturated hydrocarbon groups, and making the oxetane compound bifunctional or higher, it is possible to suppress the decrease in the glass transition temperature and adhere closely. And wet heat resistance can be improved.

The reason for this is not clear, but when a compound having an unsaturated hydrocarbon group and an oxetane compound are used in combination, they react at a close reaction rate, so that the reaction proceeds sufficiently without much mutual structural control. It is presumed that a crosslinked structure with a high degree of crosslinking is obtained, the moisture permeability of the polarizing film protective layer is suppressed, and the moisture and heat resistance of the polarizing plate is improved.

<Difunctional or higher oxetane compound (A1)>
The oxetane compound (A1) has only to be bifunctional or more. For example, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl -3-Oxetanyl) methoxymethyl] benzene, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, and the like. These oxetane compounds (A1) can be used alone or in combination of two or more.

Among these, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-, is readily available and has excellent dilutability (low viscosity) and excellent compatibility. 3 {[(3-Ethyloxetane-3-yl) methoxy] methyl} oxetane and the like are preferably used.
From the viewpoint of compatibility and adhesiveness, a liquid material having a molecular weight of 500 or less at room temperature (25 ° C.) is preferably used.

As the oxetane compound (A1), for example, commercially available products Aron Oxetane OXT-121 and Aron Oxetane OXT-221 (both manufactured by Toagosei Co., Ltd.) can be used. Aron oxetane OXT-221 is particularly preferable.

The content ratio of the oxetane compound (A1) is 51 to 99 parts by weight, preferably 55 to 95 parts by weight, and preferably 55 to 85 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition. More preferably.
If the content is too small, the adhesiveness to the polarizing film tends to be inferior, and if it is too large, the curability tends to decrease.

<Compound (B) having at least two unsaturated hydrocarbon groups>
The compound (B) is preferably a radical polymerizable monomer from the viewpoint of heat and heat resistance.
For example, a vinyl compound having a bifunctional or higher functional group, a (meth) acrylic compound having a bifunctional or higher functional group, and a (meth) acrylic group having a bifunctional or higher functional group in terms of curability. Compounds.

Examples of the (meth) acrylic compound having a bifunctional or higher functional group include a bifunctional (meth) acrylic compound and a trifunctional or higher functional (meth) acrylic compound.

Examples of the bifunctional (meth) acrylic compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4- Butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate Di (meth) having a long chain structure or branched chain structure such as ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate Acrylate; cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentanedi (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethylene oxide modified cyclohexanedimethanol di (meth) acrylate, etc. Di (meth) acrylate having; alkyle such as ethylene oxide modified bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate Di (meth) acrylates having aromatic rings such as oxide-modified bisphenol A type di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, diglycidyl phthalate di (meth) acrylate; dioxane glycol di (meth) And di (meth) acrylates having a ring structure such as acrylate and ethylene oxide modified di (meth) acrylate.

Examples of the trifunctional or higher functional (meth) acrylic compound include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and di Pentaerythritol hexa (meth) acrylate, polyglycerin poly (meth) acrylate; caprolactone modified dipentaerythritol penta (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, caprolactone modified pentaerythritol tri (meth) acrylate, caprolactone modified Pentaerythritol tetra (meth) acrylate, ethylene oxide modified dipentaerythritol penta (meth) acrylate Rate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, ethylene oxide modified glycerin tri (meth) acrylate, etc. A tri- or higher-functional (meth) acrylate having a long-chain or branched-chain structure such as a tri- or higher-functional (meth) acrylate having a structure; a tri (meth) acrylate having a ring structure such as an isocyanuric acid ethylene oxide-modified triacrylate; Etc.

Among these, bifunctional (meth) acrylic compounds are preferable from the viewpoint of the balance between adhesiveness and heat-and-moisture resistance, and 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Di (meth) acrylate having a long chain or branched chain structure such as glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, Di (meth) acrylate having dicyclic structure such as tricyclodecane dimethanol di (meth) acrylate, ethylene oxide modified cyclohexanedimethanol di (meth) acrylate, dioxane glycol di (meth) acrylate, ethylene oxide modified isocyanuric acid Di (meth) acrylate having a cyclic structure such as di (meth) acrylate are more preferred. Of these, a (meth) acrylic compound having an alicyclic structure or a ring structure is more preferable in terms of further improving the heat and moisture resistance.

Specifically, tricyclodecane dimethanol diacrylate (light acrylate DCP-A manufactured by Kyoeisha Chemical Co., Ltd.), 1,4-butanediol diacrylate (Biscoat # 195 manufactured by Osaka Organic Chemical Industry Co., Ltd.), dioxane glycol diacrylate (new And Nakamura Chemical Co., Ltd. NK Ester A-DOG).

The content of the compound (B) is preferably 1 to 49 parts by weight and preferably 5 to 45 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition from the viewpoint of heat and moisture resistance. More preferred is 15 to 45 parts by weight.

<Epoxy resin>
The second resin composition may contain an epoxy resin.

Examples of the epoxy resin include an aliphatic epoxy resin, an alicyclic epoxy resin, an epoxy resin having an aromatic ring, an epoxy resin having an alicyclic skeleton, and a polymer having an epoxy group.
Examples of the aliphatic epoxy resin include one epoxy group in the molecule such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, glycidol, alcohol glycidyl ether having 11 to 15 carbon atoms, lauryl alcohol glycidyl ether, and the like. Individual aliphatic epoxy resins, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol jig Bifunctional or higher aliphatic type having two or more epoxy groups in the molecule such as sidyl ether, polytetramethylene glycol diglycidyl ether, polybutadiene diglycidyl ether, sorbitol polyglycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether An epoxy resin is mentioned.

Examples of alicyclic epoxy resins include 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone-modified 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1 , 2-epoxy-4-vinylcyclohexane, limonene dioxide and the like.

Examples of the epoxy resin having an aromatic ring include phenol (EO) -modified glycidyl ether, alkylphenol glycidyl ether dibromophenyl glycidyl ether, bisphenol type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol novolak type epoxy resin. , Biphenol type epoxy resin, resorcinol type epoxy resin, hydroquinone type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin and the like.

Examples of the epoxy resin having an alicyclic skeleton include hydrogenated epoxy resins obtained by hydrogenating an aromatic ring of an epoxy resin having an aromatic ring, cyclohexanedimethanol diglycidyl ether, and the like.

The content of the epoxy resin in the second resin composition is preferably 45 parts by weight or less and 40 parts by weight or less with respect to 100 parts by weight of the total amount of the oxetane compound (A2) and the compound (B). More preferably, it is more preferably 35 parts by weight or less.

<Oxetane compound (A11)>
The second resin composition may contain an oxetane compound (A11) other than the oxetane compound (A1).

As the oxetane compound (A11), an oxetane compound having one oxetanyl group in the molecule can be used.
Examples of the compound include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (Cyclohexyloxymethyl) oxetane, 3-ethyl-3- (oxiranylmethoxy) oxetane, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl and the like.

[Third Embodiment]
The third resin composition contains a bifunctional or higher oxetane compound (A2) and an epoxy compound (C).

However, by increasing the oxetane compound content ratio as described below, combining it with an epoxy compound having at least one of an aromatic ring structure and an alicyclic structure, and making the oxetane compound bifunctional or more, the decrease in glass transition temperature is suppressed. In addition, the heat and moisture resistance and adhesion can be improved.

The reason is not clear, but since the oxetane compound has a higher growth rate than the epoxy compound, the polymerization reaction proceeds sufficiently, and the crosslinked structure with a high degree of crosslinking can suppress the moisture permeability of the polarizing film protective layer. It is estimated that the wet heat resistance of the polarizing plate is improved.

<Difunctional or higher oxetane compound (A2)>
The oxetane compound (A2) has only to be bifunctional or more. For example, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, 1,4-bis [(3-ethyl -3-Oxetanyl) methoxymethyl] benzene, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, and the like. These oxetane compounds (A2) can be used alone or in combination of two or more.

As the oxetane compound (A2), for example, commercially available products Aron Oxetane OXT-121 and Aron Oxetane OXT-221 (both manufactured by Toagosei Co., Ltd.) can be used. Aron oxetane OXT-221 is particularly preferable.

The content of the oxetane compound (A2) is 75 to 99 parts by weight, preferably 75 to 90 parts by weight, and preferably 75 to 85 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition. More preferably.
If the content is too small, the adhesiveness to the polarizing film tends to be inferior, and if it is too large, the curability tends to decrease.

<Epoxy compound (C)>
The epoxy compound (C) only needs to have at least one of an aromatic ring structure and an alicyclic structure, and among them, an epoxy compound having two or more epoxy groups is preferable in that it can further improve wet heat resistance.

Examples of the epoxy compound having an aromatic ring structure include phenyl glycidyl ether, phenol (EO) -modified glycidyl ether, alkylphenol glycidyl ether dibromophenyl glycidyl ether, bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol. Examples include novolac type epoxy resins, biphenol type epoxy resins, resorcinol type epoxy resins, hydroquinone type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins and the like.

Among them, bisphenol type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and bisphenol novolak type epoxy resins are preferable, and bisphenol type epoxy resins are particularly preferable.

Examples of the epoxy compound having an alicyclic structure include an epoxy resin which is a polyglycidyl ether of an alicyclic polyhydric alcohol and an alicyclic epoxy compound in which an epoxy group is directly bonded to an alicyclic ring.
Examples of epoxy resins that are polyglycidyl ethers of alicyclic polyhydric alcohols include hydrogenated epoxy resin compounds obtained by hydrogenating aromatic epoxy compounds such as bisphenol type epoxy resins, phenol novolac type epoxy resins, and cresol novolac epoxy resins. , 6-cyclohexanedimethanol diglycidyl ether and the like.

Examples of alicyclic epoxy compounds include 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone modified 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1, Examples include 2-epoxy-4-vinylcyclohexane and limonene dioxide.

These epoxy compounds can be used alone or in combination.

The content of the epoxy compound (C) is preferably 1 to 25 parts by weight and preferably 10 to 25 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition from the viewpoint of heat and moisture resistance. Is more preferably 15 to 25 parts by weight.

[Resin composition of the present invention]
<Photo acid generator>
The resin composition of the present invention preferably further contains a photoacid generator. By using a photoacid generator, a polymerization reaction proceeds, adhesion to the polarizing film is improved, and a polarizing film protective layer having sufficient strength can be obtained.

Photoacid generators are compounds that generate cation species and Lewis acids upon irradiation with active energy rays. For example, onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, iron-allene complexes Etc.

Examples of the aromatic diazonium salt include benzenediazonium / hexafluoroantimonate, benzenediazonium / hexafluorophosphate, and benzenediazonium / hexafluoroborate.

Examples of the aromatic iodonium salt include diphenyliodonium / tetrakis (pentafluorophenyl) borate, diphenyliodonium / hexafluorophosphate, diphenyliodonium / hexafluoroantimonate, di (4-nonylphenyl) iodonium / hexafluorophosphate, and the like. It is done.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium hexa Fluorophosphate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide / bishexafluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide / bishexafluoroantimonate, 4 , 4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfoni ] -2-Isopropylthioxanthone hexafluoroantimonate, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide · bishexafluoroantimonate, 7- [Di (p-toluyl) sulfonio] -2-isopropylthioxanthone / tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide / hexafluorophosphate, 4- (p-tert-butyl) Phenylcarbonyl) -4'-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfur Niobium - diphenylsulfide tetrakis (pentafluorophenyl) borate, and the like.

Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) -hexafluoroantimonate, cumene-cyclopentadienyl iron (II) -hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide and the like.

Among such photoacid generators, it is preferable to use an aromatic iodonium salt or an aromatic sulfonium salt from the viewpoint that it reacts with high sensitivity to a long wavelength light source.
Examples include diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate (CPI-100P manufactured by San Apro) and diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate (CPI-101A manufactured by San Apro). It is done.
A photo-acid generator can be used individually or in combination of 2 or more types.

The content of the photoacid generator in the first resin composition is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the oxetane compound, and 1.0 to 15 parts by weight. More preferred are parts by weight, and even more preferred is 1.5 to 10 parts by weight.

The content of the photoacid generator in the second resin composition is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound (A1) and the compound (B). The amount is more preferably 0 to 15 parts by weight, and further preferably 1.5 to 10 parts by weight.

The content of the photoacid generator in the third resin composition is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound (A2) and the epoxy compound (C). The amount is more preferably 1.0 to 15 parts by weight, and further preferably 1.5 to 10 parts by weight.

If the content of the photoacid generator is too large, the solubility tends to decrease or the heat and humidity resistance tends to decrease. Moreover, when there is too little content of a photo-acid generator, hardening will become inadequate and there exists a tendency for the adhesiveness with a polarizing film, and the intensity | strength of a polarizing film protective layer to fall.

<Photo radical initiator>
The resin composition of the present invention preferably further contains a photo radical initiator.

Examples of the photo radical initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2 -Propyl) ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone Acetophenones such as 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether Kind Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4 , 6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium chloride, etc. Benzophenones; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3 , 4-Dimethyl Thioxanthones such as -9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine And acylphosphine oxides such as bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide;
In addition, only 1 type may be used independently for these photoradical initiators, and 2 or more types may be used together.

Further, auxiliary agents for these photo radical initiators include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4- Ethyl dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4- Diisopropylthioxanthone and the like can be used in combination.

Among the above photo radical initiators, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-hydroxy-2- Methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis Acylphosphine oxides such as (2,4,6-trimethylbenzoyl) -phenylphosphine oxide are preferred.

Specifically, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (IGM Resins TPO) and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (IGM Resins Omnirad 819) are available. preferable.

The content of the photo radical initiator in the first resin composition is preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the total amount of the epoxy resin and the oxetane compound, and preferably 0.5 to 15 parts by weight. More preferred are parts by weight, and even more preferred is 0.7 to 10 parts by weight.

The content of the photo radical initiator in the second resin composition is preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound (A1) and the compound (B). More preferably, it is 5 to 15 parts by weight, and even more preferably 0.7 to 10 parts by weight.

The content of the photo radical initiator in the third resin composition is preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound (A2) and the epoxy compound (C). The amount is more preferably 0.5 to 15 parts by weight, and further preferably 0.7 to 15 parts by weight.

If the content of the photoradical initiator is too large, the low molecular weight component tends to increase and the crosslink density tends to decrease and the heat and moisture resistance tends to decrease.If the content of the photoradical initiator is too small, the curability is poor and the physical properties are poor. There is a tendency to become unstable.

<Radical polymerization component>
The resin composition of the present invention can contain a radical polymerization component.
As the radical polymerization component, a compound having at least one (meth) acryloyl group in the molecule (hereinafter sometimes referred to as “(meth) acrylic compound”) can be used.

By using a (meth) acrylic compound, the curing rate can be adjusted, and the curability tends to be improved. In addition, when using a (meth) acrylic-type compound as a radical polymerization component, it is preferable to use a photoradical initiator.

As the (meth) acrylic compound, for example, a (meth) acrylic compound having one (meth) acryloyl group in the molecule (hereinafter sometimes referred to as “monofunctional (meth) acrylic compound”). And (meth) acrylic compounds having two or more (meth) acryloyl groups in the molecule (hereinafter sometimes referred to as “polyfunctional (meth) acrylic compounds”). These (meth) acrylic compounds can be used alone or in combination of two or more.

Examples of monofunctional (meth) acrylic compounds include alkyl (meth) acrylate compounds, polar group-containing (meth) acrylic compounds, alicyclic (meth) acrylate compounds, aromatic (meth) acrylate compounds, Examples include (meth) acrylic compounds having a reactive functional group other than (meth) acryloyl group and (meth) acryloyl group in the molecule.

Examples of the alkyl (meth) acrylate compounds include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2- Examples include ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.

Examples of the polar group-containing (meth) acrylic compound include a carboxyl group-containing (meth) acrylic compound, a hydroxyl group-containing (meth) acrylate compound, a nitrogen atom-containing (meth) acrylic compound, and an alkoxy group-containing (meth) acrylate. System compounds and the like.

Examples of carboxyl group-containing (meth) acrylic compounds include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide N-glycolic acid, cinnamic acid, and (meth) acrylic. Michael adducts of acids (eg, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (eg, 2 -Acrylyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl Kisa hexahydrophthalic acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid mono ester) and the like.

Examples of the hydroxyl group-containing (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. Hydroxyalkyl (meth) acrylate compounds such as caprolactone-modified 2-hydroxyethyl (meth) acrylate and other caprolactone-modified (meth) acrylate compounds; ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, pentanediol Mono (meth) acrylate compounds of dihydric alcohols such as mono (meth) acrylate and hexanediol mono (meth) acrylate; mono (meth) acrylate of diethylene glycol, Mono (meth) acrylate of ethylene glycol, mono (meth) acrylate of tetraethylene glycol, mono (meth) acrylate of polyethylene glycol, mono (meth) acrylate of dipropylene glycol, mono (meth) acrylate of tripropylene glycol, polypropylene glycol Mono (meth) acrylate compounds of polyalkylene glycols such as mono (meth) acrylates; other primary hydroxyl group-containing (meth) acrylate compounds such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2 -Secondary hydroxyl group-containing (meth) acrylate compounds such as hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate; 2,2-dimethyl 2-hydroxyethyl (meth) acrylate Tertiary hydroxyl (meth) acrylate compound and the like; and the like.

Examples of nitrogen atom-containing (meth) acrylic compounds include amide group-containing (meth) acrylic compounds, amino group-containing (meth) acrylic compounds, and other nitrogen atom-containing (meth) acrylic compounds.

Examples of the amide group-containing (meth) acrylic compound include (meth) acrylamide; N, N-dialkyl (meth) acrylamide such as N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide; N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-isopropoxymethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N- N-alkoxyalkyl (meth) acrylamides such as isobutoxymethyl (meth) acrylamide; hydroxyl-containing acrylamides such as N- (hydroxymethyl) (meth) acrylamide; N- (3-N, N-dimethylaminopropyl) (meth) Acrylamide, methyl Nbisu (meth) acrylamide, ethylenebis (meth) acrylamide.

Examples of the amino group-containing (meth) acrylic compound include primary amino group-containing (meth) acrylates such as aminoalkyl (meth) acrylate (for example, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate), t -Secondary amino group-containing (meth) acrylates such as butylaminoethyl (meth) acrylate, dialkylaminoalkyl (meth) acrylates (eg ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) And tertiary amine group-containing (meth) acrylates such as acrylate) and heterocyclic amine monomers such as acryloylmorpholine.

Examples of alkoxy group-containing (meth) acrylate compounds include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, and the like. Alkoxyalkyl (meth) acrylate compounds, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate , Methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol-mono (meth) acrylate , Lauroxypolyethylene glycol mono (meth) acrylate, polyether chains containing such stearoxy polyethylene glycol mono (meth) acrylate (meth) acrylate compounds, and the like.

Examples of the alicyclic (meth) acrylate compounds include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 1,4-cyclohexanedimethylol mono (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclohexane. Examples include pentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 2-adamantyl (meth) acrylate, and the like.

Examples of the aromatic (meth) acrylate compound include phenyl (meth) acrylate; benzyl (meth) acrylate; phenoxyalkyl (meth) acrylate such as phenoxyethyl (meth) acrylate and phenoxypropyl (meth) acrylate; phenoxydiethylene glycol ( Phenoxydialkylene glycol (meth) acrylates such as meth) acrylate and phenoxydipropylene glycol (meth) acrylate; phenoxypolyethylene glycol (meth) acrylate; phenoxypolyethylene glycol-polypropylene glycol- (meth) acrylate; p-cumylphenol alkylene oxide Adduct (meth) acrylate, o-phenylphenol alkylene oxide adduct (meth) acrylic Over DOO, (meth) acrylate of phenol alkylene oxide adduct (meth) acrylate and nonylphenol alkylene oxide adduct.

Examples of (meth) acrylic compounds having a (meth) acryloyl group and a reactive functional group other than (meth) acryloyl group in the molecule include glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 3,4-epoxycyclohexyl. Epoxy group-containing (meth) acrylate compounds such as methyl (meth) acrylate, vinyl group-containing (meth) acrylate compounds such as 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, 2- (meth) acryloyloxy Examples include isocyanate group-containing (meth) acrylate compounds such as ethyl isocyanate. Other examples include (meth) acrylate compounds having a cyclic ether structure such as tetrahydrofurfuryl (meth) acrylate and caprolactone-modified tetrahydrofurfuryl (meth) acrylate.

Also, examples of the polyfunctional (meth) acrylic compound include a bifunctional (meth) acrylic compound and a trifunctional or higher functional (meth) acrylic compound.

Examples of the bifunctional (meth) acrylic compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6- Hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether Di (meth) acrylate having a long chain or branched chain structure such as (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, and hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate; cyclohexanedimethanol di (meth) Di (meth) acrylates having an alicyclic structure such as acrylate, dimethylol dicyclopentane di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethylene oxide modified cyclohexanedimethanol di (meth) acrylate; ethylene oxide Alkylene oxide modified bisphenol A type di (meth) acrylate such as modified bisphenol A type di (meth) acrylate and propylene oxide modified bisphenol A type di (meth) acrylate Di (meth) acrylates having aromatic rings such as bisphenol A diglycidyl ether di (meth) acrylate, diglycidyl phthalate di (meth) acrylate; ring structures such as isocyanuric acid ethylene oxide modified di (meth) acrylate Di (meth) acrylate having;

Also, oligomers such as urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate can be used as the (meth) acrylic compound.

The content of the radical polymerization component in the first resin composition is preferably 40% by weight or less from the viewpoint of heat and moisture resistance.

The content of the radical polymerization component excluding the compound (B) having at least two unsaturated hydrocarbon groups in the second resin composition is preferably 40% by weight or less from the viewpoint of heat and humidity resistance.

The content of the radical polymerization component in the third resin composition is preferably 20% by weight or less from the viewpoint of heat and moisture resistance.

<Other additives>
The resin composition of the present invention can contain other additives in addition to the above components as long as the effects of the present invention are not impaired.
Examples of other additives include photosensitizers; polyols; antistatic agents; adhesives; acrylic resins; urethane resins; rosins, rosin esters, hydrogenated rosin esters, phenol resins, aromatic modified terpene resins, Tackifiers such as aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins; plasticizers; colorants; fillers; anti-aging agents; ultraviolet absorbers; functional dyes; Examples thereof include compounds that cause coloration or discoloration upon irradiation.

The content of other additives in the resin composition of the present invention is preferably 30% by weight or less, more preferably 20% by weight or less from the viewpoint of heat and moisture resistance.

Further, the resin composition of the present invention may contain a small amount of impurities contained in the raw materials for producing the constituent components of the active energy ray-curable resin composition in addition to the above additives.

<Method for producing active energy ray-curable resin composition>
The resin composition of the present invention is obtained by blending at a predetermined ratio using each of the above components and mixing them.

[Polarizing film protective layer]
The polarizing film protective layer of the present invention can be obtained by curing the resin composition of the present invention. The conditions for curing the resin composition of the present invention will be described in detail below.

[Polarizer]
The polarizing plate of the present invention has the polarizing film protective layer of the present invention. Specifically, the polarizing plate of the present invention has the polarizing film protective layer of the present invention on the polarizing film.
The polarizing plate of the present invention can be obtained by irradiating at least one surface, preferably both surfaces, of the polarizing film of the present invention with active energy ray irradiation on the resin composition of the present invention applied or bonded.

As the polarizing film, a film made of a PVA resin having an average degree of polymerization of 1,500 to 10,000 and a degree of saponification of 85 to 100 mol% is usually used as an original film, and an iodine-potassium iodide aqueous solution or two. A uniaxially stretched film dyed with a chromatic dye (usually a stretch ratio of about 2 to 10 times, preferably about 3 to 7 times) is used.

PVA-based resins are usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but a small amount of unsaturated carboxylic acid (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, A component copolymerizable with vinyl acetate such as a saturated sulfonate may be contained. Further, for example, so-called polyvinyl acetal resins and PVA derivatives such as polybutyral resins and polyvinyl formal resins obtained by reacting PVA resins with aldehydes in the presence of an acid can also be used.

As the active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. Ultraviolet rays are advantageous because of their availability and price.

A high pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, an LED lamp, or the like is used as a light source for ultraviolet irradiation.
UV irradiation is usually ² ~ 3000mJ / cm 2 in the integrated wavelength 365 nm, preferably carried out at a 10 ~ 2000mJ / cm ² conditions.

Particularly, the case of using the high-pressure mercury lamp, for example, usually 5 ~ 3000mJ / cm ^2, preferably at a 50 ~ 2000mJ / cm ² conditions.
When the electrodeless lamp is used, for example, it is usually performed under conditions of 2 to 2000 mJ / cm ² , preferably 10 to 1000 mJ / cm ² .

The irradiation time varies depending on the type of light source, the distance between the light source and the coating surface, the coating thickness, and other conditions, but it is usually several seconds to several tens of seconds, and in some cases, may be a fraction of a second.
On the other hand, in the case of the electron beam irradiation, for example, an electron beam having an energy in the range of 50 to 1000 keV is used and the irradiation amount is preferably 2 to 50 Mrad.

Active energy rays (ultraviolet rays, electron beams, etc.) can be irradiated from any appropriate direction, but are preferably irradiated from the coated surface side of the curable resin composition in terms of preventing uneven curing.

The thickness of the polarizing film protective layer in the polarizing plate of the present invention obtained by the above operation is usually 0.1 to 30 μm, preferably 0.2 to 25 μm, particularly preferably 0.3 to 20 μm, more preferably 0.5. ~ 15 μm. If the thickness is too thin, the heat and humidity resistance tends to be insufficient, and if the thickness is too thick, the workability of the polarizing plate tends to deteriorate due to cracks during punching.

The resin composition of the present invention exhibits very excellent moisture and heat resistance when used for protecting various polarizing films.
Moreover, this invention relates also to the method of protecting a polarizing film using the resin composition of this invention.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, “part” means a weight basis.

[Test Example 1]
Prior to the examples and comparative examples, each component of the curable resin composition shown below was prepared.

[Epoxy resin]
Epoxy resin 1-1: bisphenol A type epoxy resin (Mitsubishi Chemical Corporation jER1256, epoxy equivalent: 8000)
Epoxy resin 1-2: bisphenol A type epoxy resin (Mitsubishi Chemical Corporation jER1004, epoxy equivalent: 925)
Epoxy resin 1-3: bisphenol A type epoxy resin (jER828 manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 190)

[Oxetane compound]
Compound name 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (OXT-221 manufactured by Toagosei Co., Ltd.)

[Photoacid generator]
Compound name Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate (CPI-100P manufactured by San Apro)

[Examples 1-1 to 1-3, Comparative Examples 1-1 to 1-2]
<Preparation of active energy ray-curable resin composition>
An active energy ray-curable resin composition was prepared by blending the above components at a ratio shown in Table 1 and mixing them.

<Preparation of polarizing film>
First, a 60 μm PVA film was stretched 1.5 times while immersed in a water bath with a water temperature of 30 ° C.
Next, the PVA film was stretched 1.3 times while being immersed for 240 seconds in a dyeing tank (30 ° C.) consisting of 0.2 g / L of iodine and 15 g / L of potassium iodide.
Furthermore, the PVA film is immersed in a boric acid treatment tank (50 ° C.) having a composition of boric acid 50 g / L and potassium iodide 30 g / L, and at the same time uniaxially stretched 3.08 times for boric acid treatment for 5 minutes. went.
Thereafter, the PVA film was dried at 90 ° C. to produce a polarizing film having a total draw ratio of 6 times.

<Preparation of polarizing plate test piece>
The curable resin composition obtained above was applied to one side of the polarizing film obtained above using a bar coater so that the film thickness after drying was 15 μm.
About the composition containing a solvent, the solvent was removed by drying at 80 degreeC for 3 minute (s).

The coated surface is irradiated with ultraviolet rays at a peak illuminance of 1,000 mW / cm ² and an integrated exposure amount of 500 mJ / cm ² (wavelength 365 nm) using an ultraviolet irradiation apparatus equipped with a high-pressure mercury lamp, and a curable resin composition is obtained. A polarizing plate was prepared by curing to form a protective layer.

The obtained polarizing plate was cut into a size of 40 mm × 40 mm, and the surface on the opposite side of the protective layer of the polarizing plate was bonded to glass through a pressure-sensitive adhesive having a thickness of 20 μm.

<Performance evaluation>
(Moisture and heat resistance)
The obtained polarizing plate with glass was left in a constant temperature and humidity chamber at 60 ° C. and 90% for 500 hours, and then the degree of polarization of the polarizing plate was measured with an automatic polarizing film measuring device VAP-7070S (manufactured by JASCO Corporation). It was measured. The degree of polarization of the polarizing plate was evaluated according to the following criteria. The results are shown in Table 1.

○: The degree of polarization after standing for 500 hours was 99.9% or more.
Δ: The degree of polarization after standing for 500 hours was 99.0% or more and less than 99.9%.
X: The degree of polarization after standing for 500 hours was less than 99.0%.

From the above results, it was found that the polarizing plates of Examples 1-1 to 1-3 had a high degree of polarization after being left under high temperature and high humidity and were excellent in wet heat resistance.

[Test Example 2]
Prior to the examples and comparative examples, each component of the curable resin composition shown below was prepared.

[Oxetane compound]
Oxetane compound 2-1 (bifunctional): Compound name 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (Aron Oxetane OXT-221 manufactured by Toagosei Co., Ltd.)
Oxetane compound 2-2 (monofunctional): Compound name 3-ethyl-3-hydroxymethyloxetane (Aron Oxetane OXT-101 manufactured by Toagosei Co., Ltd.)

[Compound having an unsaturated hydrocarbon group]
Radical polymerizable compound 2-1 (bifunctional): Compound name Tricyclodecane dimethanol diacrylate (Kyoeisha Chemical Co., Ltd. Light acrylate DCP-A)
Radical polymerizable compound 2-2 (bifunctional): Compound name 1,4-butanediol diacrylate (Biscoat # 195, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
Radical polymerizable compound 2-3 (bifunctional): Compound name Dioxane glycol diacrylate (NK ester A-DOG manufactured by Shin-Nakamura Chemical Co., Ltd.)
Radical polymerizable compound 2-4 (monofunctional): Compound name dicyclopentanyl acrylate (Hankuri FA-513AS manufactured by Hitachi Chemical Co., Ltd.)

[Photo radical initiator]
Compound name 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (Omnirad TPO manufactured by IGM Resins)

[Examples 2-1 to 2-4, Comparative Examples 2-1 to 2-4]
<Preparation of active energy ray-curable resin composition>
An active energy ray-curable resin composition was prepared by blending the above components at a ratio shown in Table 2 and mixing them.

<Preparation of polarizing plate test piece>
The curable resin composition obtained above was coated on one side of the polarizing film obtained above using a bar coater so that the film thickness after drying was 15 μm.
A release PET film (SPPET3801BU thickness 38 μm manufactured by Mitsui Chemicals, Inc.) was bonded to the coated surface.
Curable resin composition by irradiating ultraviolet rays from the release PET film surface with a peak illuminance of 1,000 mW / cm ² and an integrated exposure amount of 500 mJ / cm ² (wavelength 365 nm) with an ultraviolet irradiation device equipped with a high-pressure mercury lamp. The product was cured to form a protective layer to produce a polarizing plate.

The other side of the polarizing film is coated with the curable resin composition obtained above using a bar coater so that the film thickness after drying is 15 μm, and the release PET film is coated on the coated surface. Pasted together.
The curable resin composition was cured by irradiating with ultraviolet rays under the same conditions as described above to obtain a protective layer.

The polarizing plate which has the protective layer which hardened the curable resin composition on both surfaces of the polarizing film was produced by peeling each release PET film.

<Performance evaluation>
(Curable)
The tackiness of the curable resin composition when the release PET film was peeled off immediately after UV irradiation was confirmed with a finger. The tack property was evaluated according to the following criteria. The results are shown in Table 2.

○: No tackiness remained.
X: Tackiness remained.

(Adhesion)
The obtained polarizing plate was cut into a size of 40 mm × 40 mm and bonded to glass via a pressure sensitive adhesive. The obtained polarizing plate with glass was cut with a cutter vertically and horizontally at intervals of 2 mm to prepare 100 grids, and the adhesion between the polarizing film and the resin composition was confirmed. The adhesion was evaluated according to the following criteria. The results are shown in Table 2.

○: No peeling at all.
X: There was a peeling part.

(Moisture and heat resistance)
The obtained polarizing plate was cut into a size of 40 mm × 40 mm, and bonded to glass through a pressure-sensitive adhesive having a thickness of 20 μm.
The obtained polarizing plate with glass was left in a constant temperature and humidity chamber at 60 ° C. and 90% for 500 hours, and then the degree of polarization of the polarizing plate was measured with an automatic polarizing film measuring device VAP-7070S (manufactured by JASCO Corporation). did. The degree of polarization of the polarizing plate was evaluated according to the following criteria. The results are shown in Table 2.

○: The degree of polarization after standing for 500 hours was 99.9% or more.
Δ: The degree of polarization after standing for 500 hours was 98.0% or more and less than 99.9%.
X: The degree of polarization after standing for 500 hours was less than 98.0%.

From the above results, it was found that the active energy ray-curable resin compositions of Examples 2-1 to 2-4 were excellent in curability.
Moreover, the said resin composition can form the polarizing film protective layer excellent in adhesiveness with a polarizing film, and when the said polarizing film protective layer was used, it turned out that the polarizing plate excellent in moisture-heat resistance can be obtained.

[Test Example 3]
Prior to the examples and comparative examples, each component of the curable resin composition shown below was prepared.

[Oxetane compound]
Oxetane compound (bifunctional): Compound name 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (OXT-221 manufactured by Toagosei Co., Ltd.)

[Epoxy compound]
Epoxy compound 3-1 (alicyclic): Compound name 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (CEL2021P manufactured by Daicel)
Epoxy compound 3-2 (containing alicyclic structure): Compound name hydrogenated bisphenol A type epoxy resin (YX8000 manufactured by Mitsubishi Chemical Corporation)
Epoxy compound 3-3 (containing aromatic ring structure): Compound name bisphenol A type epoxy resin (jER1009 manufactured by Mitsubishi Chemical Corporation)
Epoxy compound 3-4 (aliphatic): Compound name 1,4-butanediol diglycidyl ether (EX-214L manufactured by Nagase ChemteX Corporation)

[Examples 3-1 to 3-3, Comparative Examples 3-1 to 3-3]
<Preparation of active energy ray-curable resin composition>
An active energy ray-curable resin composition was prepared by blending and mixing the above components in the proportions shown in Table 3.

<Preparation of polarizing plate test piece>
The curable resin composition obtained above was applied to one side of the polarizing film obtained above using a bar coater so that the film thickness after drying was 15 μm.
A release PET film (SPPET3801BU thickness 38 μm manufactured by Mitsui Chemicals, Inc.) was bonded to the coated surface.
Curable resin composition by irradiating ultraviolet rays from the release PET film surface with a peak illuminance of 1,000 mW / cm ² and an integrated exposure amount of 500 mJ / cm ² (wavelength 365 nm) with an ultraviolet irradiation device equipped with a high-pressure mercury lamp. The product was cured to form a protective layer to produce a polarizing plate.

<Performance evaluation>
(Curable)
The tackiness of the curable resin composition when the release PET film was peeled off immediately after UV irradiation was confirmed with a finger. The tack property was evaluated according to the following criteria. The results are shown in Table 3.

○: No tackiness remained.
X: Tackiness remained.

(Moisture and heat resistance)
The obtained polarizing plate was cut into a size of 40 mm × 40 mm, and bonded to glass through a pressure-sensitive adhesive having a thickness of 20 μm.
The obtained polarizing plate with glass was left in a constant temperature and humidity chamber at 60 ° C. and 90% for 500 hours, and then the degree of polarization of the polarizing plate was measured with an automatic polarizing film measuring device VAP-7070S (manufactured by JASCO Corporation). did. The degree of polarization of the polarizing plate was evaluated according to the following criteria. The results are shown in Table 3.

From the above results, it was found that the active energy ray-curable resin compositions of Examples 3-1 to 3-3 were excellent in curability.
Moreover, when the polarizing film protective layer obtained from the said resin composition was used, it turned out that the polarizing plate excellent in heat-and-moisture resistance can be obtained.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application includes Japanese patent applications filed on March 22, 2018 (Japanese Patent Application No. 2018-054226), Japanese patent applications filed on July 26, 2018 (Japanese Patent Application No. 2018-140747), and applications filed on July 26, 2018. Based on Japanese Patent Application (Japanese Patent Application No. 2018-140748), the contents of which are incorporated herein by reference.

The resin composition of the present invention, the polarizing film protective layer obtained by curing the resin composition, and the polarizing plate having the protective layer are excellent in moisture and heat resistance and can be suitably used for image display devices such as liquid crystal display devices.

Claims

An active energy ray-curable resin composition for protecting a polarizing film, which contains an epoxy resin having an epoxy equivalent of 300 or more.
The active energy ray-curable resin composition according to claim 1, wherein the epoxy resin has an aromatic ring or an alicyclic skeleton.
The active energy ray-curable resin composition according to claim 1 or 2, comprising an oxetane compound.
The active energy ray-curable resin composition according to claim 3, wherein a content ratio of the oxetane compound is 1 to 90 parts by weight with respect to 100 parts by weight of a total amount of the epoxy resin and the oxetane compound.
An active energy ray-curable resin composition for protecting a polarizing film, comprising a bifunctional or higher functional oxetane compound (A1) and a compound (B) having at least two unsaturated hydrocarbon groups,
An active energy ray-curable resin composition, wherein a content ratio of the oxetane compound (A1) is 51 to 99 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition.
The active energy ray-curable resin composition according to claim 5, wherein the compound (B) is a radical polymerizable monomer.
An active energy ray-curable resin composition for protecting a polarizing film containing a bifunctional or higher functional oxetane compound (A2) and an epoxy compound (C),
The content ratio of the oxetane compound (A2) is 75 to 99 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition,
The active energy ray-curable resin composition, wherein the epoxy compound (C) has at least one of an aromatic ring structure and an alicyclic structure.
The active energy ray-curable resin composition according to any one of claims 1 to 7, comprising a photoacid generator.
The active energy ray-curable resin composition according to any one of claims 1 to 8, which contains a photo radical initiator.
A polarizing film protective layer obtained by curing the active energy ray-curable resin composition according to any one of claims 1 to 9.
A polarizing plate having the polarizing film protective layer according to claim 10.