CN103168083B - The optical component of Adhesive composition for optical component, optical component tackiness agent, band binder layer and image display device - Google Patents

Abstract

There is provided a kind of Adhesive composition for optical component, it can reach taking into account re-workability and weather resistance, and can suppress irregular colour, light leakage phenomena when being applied to the image display devices such as LCD panel.The present invention relates to Adhesive composition for optical component, it is characterized in that, it is the acrylic resin (A) obtained containing the copolymer composition [I] that is main component with (methyl) alkyl-acrylates monomer (a1) is carried out copolymerization, and containing N-(alkoxyalkyl) (methyl) acrylamide monomers (a2) is as copolymer composition [I].

Description

Adhesive composition for optical member, adhesive for optical member, optical member with adhesive layer, and image display device

technical field

The present invention relates to an adhesive composition for optical members, an adhesive for optical members, an optical member with an adhesive layer, and an image display device. Specifically, it relates to optical members such as optical films (polarizing films, retardation films, optical compensation films, and brightness enhancement films) suitable for image display devices such as liquid crystal display devices, organic EL display devices, and PDPs (plasma display panels). More specifically, In other words, it relates to an adhesive composition for optical members for bonding an optical laminate in which a polarizing film is covered with a protective film such as a cellulose triacetate film and a glass substrate of a liquid crystal cell, and the adhesive composition obtained by crosslinking adhesive for optical members, an optical member with an adhesive layer formed with an adhesive layer comprising the adhesive for optical members, especially a polarizing plate with an adhesive layer, and further comprising the adhesive The image display device of the optical member of the agent layer.

Background technique

Hitherto, research has been conducted on the production of a liquid crystal display panel by laminating a polarizing plate with a protective film such as a cellulose-based film on the surface of a liquid crystal cell having an oriented liquid crystal component between two glass plates. It is formed by covering both sides of a polarizing plate such as a polyvinyl alcohol-based film to which polarizing properties are imparted, and is usually laminated on the surface of the liquid crystal cell by bringing the adhesive layer provided on the surface of the polarizing plate into contact with the surface of the liquid crystal cell and pressing to proceed.

For the adhesive forming the adhesive layer, when an optical member such as a polarizing plate is peeled from the liquid crystal cell due to a mistake in processing or the mixing of impurities, reworkability (repeatability) that can be easily peeled off without adhesive residue is required. sex). In addition, when exposed to severe environments such as high temperature and high humidity for a long time, peeling and blistering by the adhesive may occur, and durability is also required for the adhesive forming the adhesive layer. Furthermore, when the dimensional change occurs due to the passage of time of the polarizing plate, since the adhesive layer deforms following the dimensional change of the polarizing plate, the polymer in the adhesive layer is partially oriented, thereby causing birefringence, This results in color unevenness and light leakage such that the peripheral portion of the liquid crystal display panel is brighter or darker than the center. Therefore, the adhesive that forms the adhesive layer is also required to suppress color unevenness and light leakage due to stress accompanying dimensional changes in optical members such as polarizing plates.

In order to solve the above problems, Patent Document 1 discloses a (meth)acrylic polymer containing a tertiary amino group-containing monomer (acrylic acid ester and acrylamide described in paragraph 0036 of the same document). Patent Document 2 discloses an adhesive polarizing plate on which an acrylic adhesive layer containing a specific silane coupling agent is laminated.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2009-215528

Patent Document 2: Japanese Patent Application Laid-Open No. 9-288214

Contents of the invention

The problem to be solved by the invention

However, with prior art technologies such as Patent Documents 1 and 2, it is difficult to achieve a balance between reworkability and durability when exposed to high temperature and high humidity for a long time. However, there is still room for further improvement of the problem that the reworkability deteriorates when the durability is improved.

The present invention has been made in view of the above circumstances, and its object is to provide an adhesive for optical members that can achieve both rework and durability, and can suppress color unevenness and light leakage when applied to image display devices such as liquid crystal display panels. A mixture composition; an optical member adhesive obtained by crosslinking the adhesive composition; an optical member with an adhesive layer formed with an adhesive layer comprising the optical member adhesive; comprising the An image display device of an optical member with an adhesive layer.

solutions to problems

The inventors of the present invention conducted in-depth research in view of the above-mentioned actual situation, and found that by using an acrylic resin containing N-(alkoxyalkyl)(meth)acrylamide monomer as a copolymerization component, it is possible to achieve a high degree of reworkability and Durability is taken into consideration, and color unevenness and light leakage can be suppressed when applied to an image display device, thereby completing the present invention, wherein the N-(alkoxyalkyl)(meth)acrylamide monomer is A (meth)acrylamide-based monomer, and the alkyl chain bonded to the nitrogen atom of the amide bond is substituted with an alkoxy group.

That is, the gist of the present invention relates to an adhesive composition for optical members, which is characterized in that it contains a copolymerization component [I] mainly composed of an alkyl (meth)acrylate monomer (a1). The obtained acrylic resin (A) is formed, and contains an N-(alkoxyalkyl)(meth)acrylamide monomer (a2) as a copolymerization component [I].

Furthermore, it also relates to the optical member adhesive for optical members obtained by crosslinking the said adhesive composition for optical members, and the optical member with an adhesive layer which consists of the adhesive layer of the said adhesive for optical members . An image display device comprising the optical member with an adhesive layer.

The present invention includes the following embodiments.

[1] An adhesive composition for optical members, which is obtained by copolymerizing a copolymerization component [I] mainly composed of an alkyl (meth)acrylate monomer (a1) It is made of an acrylic resin (A) and contains an N-(alkoxyalkyl)(meth)acrylamide monomer (a2) as a copolymerization component [I].

[2] The adhesive composition for optical members according to [1], which contains at least one selected from aromatic ring-containing monomers (a3) and carboxyl group-containing monomers (a4) as a copolymerization component. [I].

[3] The adhesive composition for optical members according to [1] or [2], which contains a crosslinking agent (B).

[4] The adhesive composition for optical members according to any one of [1] to [3], which contains a silane coupling agent (C).

[5] An adhesive for optical members obtained by cross-linking the adhesive composition for optical members according to any one of [1] to [4].

[6] The adhesive for optical members according to [5], wherein the optical member is a polarizing plate.

[7] An optical member with an adhesive layer comprising a laminated structure of an adhesive layer and an optical member, the adhesive layer comprising the optical member described in [5] or [6] Use adhesive.

[8] An image display device comprising the optical member with an adhesive layer according to [7].

[9] The optical member with an adhesive layer according to [7], wherein the optical member is a polarizing plate.

The effect of the invention

The adhesive for optical members obtained by cross-linking the adhesive composition for optical members of the present invention is excellent in reworkability, so when processing mistakes or contamination of impurities, optical members such as polarizing plates are detached from liquid crystal cells. When peeling off, it can be easily peeled off without adhesive residue. In addition, the adhesive of the present invention has excellent durability when exposed to high temperature and high humidity for a long time, so even in a high temperature and high humidity environment and repeated environmental changes from low temperature to high temperature, an optical laminate can be obtained. It is an image display device that has excellent adhesiveness between a polarizing plate and a glass substrate, and is less prone to blistering and peeling between the adhesive layer and the glass substrate. Furthermore, for an optical member with an adhesive layer formed with an adhesive layer comprising the adhesive of the present invention, even when a dimensional change occurs due to the passage of time of the optical member, since the double layer of the adhesive layer can be made Since the refraction is close to 0, color unevenness and light leakage can be suppressed in an image display device including the optical member with an adhesive layer.

Detailed ways

Hereinafter, the present invention will be described in detail, and an example of a preferred embodiment will be shown. It should be noted that in the present invention, (meth)acrylic acid refers to acrylic acid or methacrylic acid, (meth)acryloyl refers to acryloyl or methacryloyl, and (meth)acrylate refers to acrylate or methacrylic acid. base acrylate.

[Adhesive composition for optical member]

First, the adhesive composition for optical members (henceforth simply referred to as "adhesive composition") of the present invention will be described.

The adhesive composition of this invention is a composition containing an acrylic resin (A).

The acrylic resin (A) used in the present invention is mainly composed of (meth)acrylic acid alkyl ester monomer (a1), and further contains N-(alkoxyalkyl)(meth)acrylamide monomer The body (a2) is preferably obtained by copolymerizing the copolymerization component [I] containing an aromatic ring-containing monomer (a3) and/or a carboxyl group-containing monomer (a4) as an essential component.

As the alkyl (meth)acrylate monomer (a1), the number of carbon atoms in the alkyl group is usually preferably 1 to 20, particularly preferably 1 to 12, more preferably 1 to 8, and especially preferably 4 to 8, specifically methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate ester, n-propyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isodecyl (meth)acrylate, Lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

Among the alkyl (meth)acrylate monomers (a1), n-butyl (meth)acrylate, (meth)acrylate, ) 2-ethylhexyl acrylate, and n-butyl (meth)acrylate is more preferably used from the viewpoint of excellent durability.

The "main component" of the alkyl (meth)acrylate monomer (a1) means that the alkyl (meth)acrylate monomer ( a1). The content ratio of the alkyl (meth)acrylate monomer (a1) to the entire copolymerization component [I] is preferably 50 to 97% by weight, particularly preferably 60 to 95% by weight, and more preferably 80 to 93% by weight. %.

When the content ratio of the alkyl (meth)acrylate monomer (a1) is too small, the adhesive strength tends to be insufficient when the adhesive composition is crosslinked and used as an adhesive.

As the N-(alkoxyalkyl)(meth)acrylamide monomer (a2), the number of carbon atoms in the alkoxy group is usually preferably 1 to 10, particularly preferably 1 to 8, and more preferably 1 to 8. 6. Especially preferably 1 to 4. The number of carbon atoms in the alkyl group is usually preferably 1 to 6, particularly preferably 1 to 4, further preferably 1 to 2, and especially preferably 1. Specifically, for example, N -(methoxymethyl)(meth)acrylamide, N-(n-butoxymethyl)(meth)acrylamide, N-(isobutoxymethyl)(meth)acrylamide, N -(n-butoxyethyl)(meth)acrylamide, etc. From the standpoint of excellent balance between durability and reworkability, N-(n-butoxymethyl)acrylamide, N- (Methoxymethyl)acrylamide, N-(isobutoxymethyl)acrylamide. These may be used alone or in combination of two or more.

The content ratio of the N-(alkoxyalkyl)(meth)acrylamide-based monomer (a2) to the entire copolymerization component [I] is preferably 0.1 to 3% by weight, particularly preferably 0.3 to 2% by weight, More preferably, it is 0.3 to 1% by weight.

When the content ratio of the N-(alkoxyalkyl)(meth)acrylamide-based monomer (a2) is too small, the durability and reworkability tend to decrease due to insufficient cohesive force, and when it is too large, the viscosity becomes high Or the tendency for the stability of the resin to decrease.

Examples of the aromatic ring-containing monomer (a3) include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, ethoxylated o-phenyl (meth)acrylate Phenylphenyl ester, phenyldiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropenyl (meth)acrylate, styrene, α-methylstyrene, etc., among these, From the viewpoint of excellent light leakage resistance, phenyldiethylene glycol acrylate and phenoxyethyl acrylate are preferably used. These may be used alone or in combination of two or more.

The content ratio of the aromatic ring-containing monomer (a3) to the entire copolymerization component [I] is preferably 3 to 20% by weight, particularly preferably 3 to 15% by weight, and even more preferably 5 to 15% by weight.

When the content ratio of the aromatic ring-containing monomer (a3) is too small, the light leakage resistance (light leakage suppression performance) tends to decrease easily, and when it is too large, the light leakage resistance decreases, the adhesive property of the acrylic resin deteriorates, or the polymerization stability tendency to decline.

Examples of the carboxyl group-containing monomer (a4) include (meth)acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acid, acrylamide-N-glycolic acid, cinnamic acid, etc., among which (meth)acrylic acid is preferably used. These may be used alone or in combination of two or more.

The content ratio of the carboxyl group-containing monomer (a4) to the entire copolymerization component [I] is preferably 1.5% by weight or less, particularly preferably 0.05 to 1% by weight, and even more preferably 0.05 to 0.6% by weight.

When the content ratio of the carboxyl group-containing monomer (a4) is too small, the cohesive force tends to be insufficient and the durability tends to decrease, and when it is too large, the viscosity tends to increase or the stability of the resin tends to deteriorate.

The acrylic resin (A) used in the present invention may contain other copolymerizable monomers (a5) as the copolymerization component [I] in addition to the above-mentioned monomers (a1) to (a4). Examples of the other copolymerizable monomer (a5) include hydroxyl-containing monomers, amino-containing monomers, acetoacetyl-containing monomers, isocyanate-containing monomers, and glycidyl-containing monomers. Among them, it is preferable to use a hydroxyl group-containing monomer from the viewpoint that the crosslinking reaction can efficiently proceed.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, (methyl) Hydroxyalkyl acrylates such as 6-hydroxyhexyl acrylate and 8-hydroxyoctyl (meth)acrylate, caprolactone-modified monomers such as 2-hydroxyethyl (meth)acrylate , diethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate and other alkylene oxide modified monomers, and 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, Primary hydroxyl-containing monomers such as N-methylol (meth)acrylamide, (meth)acrylate-2-hydroxypropyl, (meth)acrylate-2-hydroxybutyl, (meth)acrylate-3- Chloro-2-hydroxypropyl ester, (meth)acrylic acid-2-hydroxy-3-phenoxypropyl ester and other secondary hydroxyl-containing monomers, (meth)acrylic acid-2,2-dimethyl-2-hydroxyethyl Tertiary hydroxyl-containing monomers such as esters.

Among hydroxyl group-containing monomers, primary hydroxyl group-containing monomers are preferred from the viewpoint of excellent reactivity with crosslinking agents. Furthermore, it is particularly preferable to use 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate from the viewpoint of less impurities such as di(meth)acrylate and ease of production.

In addition, as the hydroxyl group-containing monomer used in the present invention, it is preferable to use a di(meth)acrylate content ratio of 0.5% by weight or less as an impurity, more preferably 0.2% by weight or less, and particularly preferably 0.1% by weight. Hereinafter, specifically, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are preferably used.

Examples of amino group-containing monomers include tert-butylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, (meth)acrylic acid Diethylaminoethyl ester, etc.

Examples of the acetoacetyl group-containing monomer include 2-(acetoacetoxy)ethyl (meth)acrylate, allyl acetoacetate, and the like.

As an isocyanate group containing monomer, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, these alkylene oxide adducts, etc. are mentioned, for example.

Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate, allyl glycidyl (meth)acrylate, and the like.

Other examples of other copolymerizable monomers (a5) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-Methoxybutyl, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (methyl) Acrylates, Methoxytriethylene glycol (meth)acrylate, Ethoxydiethylene glycol (meth)acrylate, Methoxydipropylene glycol (meth)acrylate, Methoxypolyethylene glycol (Meth)acrylate, Octyloxypolyethylene glycol-polypropylene glycol-mono(meth)acrylate, Lauryloxypolyethylene glycol mono(meth)acrylate, Stearyloxypolyethylene glycol mono (Meth)acrylates and other monomers containing alkoxy groups and oxyalkylene groups;

Acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, Dialkyl Conate, Dialkyl Fumarate, Allyl Alcohol, Acryloyl Chloride, Methyl Vinyl Ketone, N-Acrylamidomethyl Trimethyl Ammonium Chloride, Allyl Trimethyl Ammonium Chloride , Dimethyl allyl vinyl ketone, etc.

The content ratio of other copolymerizable monomers (a5) to the total copolymerization component [I] is preferably 5% by weight or less, particularly preferably 0.5 to 3% by weight, and even more preferably 0.4 to 1.6% by weight.

When the content rate of other copolymerizable monomer (a5) is too large, it will become difficult to acquire the effect of this invention.

In the present invention, other copolymerizable monomers (a5) may be used in combination with monomers other than N-(alkoxyalkyl)(meth)acrylamide monomers (a2) within the range not impairing the effect of the present invention. Amide monomers (i.e., amide monomers without alkoxyalkyl groups, such as (meth)acryloylmorpholine, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, diethyl(meth)acrylamide, Methylamino (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, etc.) as the copolymerization component [I].

In addition, when an amide-based monomer other than the N-(alkoxyalkyl)(meth)acrylamide-based monomer (a2) is used in combination as the above-mentioned copolymerizable monomer (a5), the content thereof relative to the copolymerization component [I] Generally, 0.1 to 2% by weight is sufficient, preferably 0.3 to 1% by weight or less, or 0 to 100% by weight, preferably 0 to 50% by weight, particularly preferably 0 to 20% by weight.

In addition, the total content ratio of the N-(alkoxyalkyl)(meth)acrylamide-based monomer (a2) and the carboxyl group-containing monomer (a4) is preferably 4% by weight or less with respect to the entire copolymerization component [I]. Especially preferably, it is 0.3 to 2 weight%, More preferably, it is 0.4 to 1.6 weight%.

When the total content ratio of (a2) and (a4) is too large, the viscosity tends to become too high or the stability of the resin tends to decrease.

For the purpose of increasing the molecular weight of the acrylic resin (A) used in the present invention, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate can be used in combination. Compounds having two or more ethylenically unsaturated groups such as alcohol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and divinylbenzene.

In the present invention, the copolymerization component [I] containing at least the above-mentioned (a1) and (a2) monomers, preferably (a3), (a4) monomers, and optionally (a5) monomers Copolymerization is performed to produce the acrylic resin (A), and this copolymerization can be performed by conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. For example, mixing or dropping (meth)acrylic acid alkyl monomer (a1), N-(alkoxyalkyl) (meth)acrylamide monomer (a2), aromatic ring-containing polymerizable monomers such as monomer (a3), carboxyl group-containing monomer (a4), and other copolymerizable monomers (a5), and a polymerization initiator, and polymerize in a reflux state or at 50-90°C for 2-20 hours.

Examples of organic solvents used in this polymerization include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as n-propanol and isopropanol; acetone, methyl ethyl ketone, Ketones such as methyl isobutyl ketone and cyclohexanone, etc.

Examples of the polymerization initiator used in this radical copolymerization include azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, and peroxides, which are common radical polymerization initiators. Specific examples include peroxide-based polymerization initiators such as benzoyl, lauroyl peroxide, di-tert-butyl peroxide, and cumene hydroperoxide.

The weight-average molecular weight (Mw) of the acrylic resin (A) is usually 400,000 to 2 million, preferably 450,000 to 1.9 million, particularly preferably 500,000 to 1.8 million. When the weight-average molecular weight is too small, the durability tends to decrease, and when it is too large, a large amount of diluting solvent is required, which tends to be unpreferable in terms of coatability and cost.

The degree of dispersion (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the acrylic resin (A) is preferably 20 or less, particularly preferably 15 or less, further preferably 10 or less, and especially preferably 7 or less. When the dispersion is too high, the durability of the pressure-sensitive adhesive layer tends to decrease and foaming tends to occur easily. However, the lower limit of the degree of dispersion is usually 2 from the viewpoint of production limits.

Furthermore, the glass transition temperature of the acrylic resin (A) is preferably -80 to -20°C, particularly preferably -75 to -30°C, and more preferably -60 to -40°C. When the glass transition temperature is too high, The viscosity tends to be insufficient, and when it is too low, the heat resistance tends to decrease.

Among them, the above-mentioned weight average molecular weight (Mw) is the weight average molecular weight based on the standard polystyrene molecular weight conversion, and is used in high performance liquid chromatography (manufactured by Japan Waters Corporation "Waters2695 (main body)" and "Waters2414 (detector)" in series 3 chromatographic columns: ShodexGPCKF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100～2×10 ⁷ , number of theoretical plates: 10,000 segments/support, packing material: styrene-divinylbenzene Copolymer, filler particle size: 10μm), the number average molecular weight (Mn) can also be measured by the same method. In addition, the degree of dispersion can be obtained from the weight average molecular weight and number average molecular weight. In addition, the glass transition temperature is obtained by It can be calculated by the following Fox formula.

[mathematical formula 1]

$\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Tg</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Wa</span>}}{\mathrm{<span\; class="notranslate">\; Tga</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; wb</span>}}{\mathrm{<span\; class="notranslate">\; Tgb</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; Tgn</span>}}$

Tg: glass transition temperature (K) of the copolymer.

Tga: glass transition temperature of homopolymer of monomer A (K) Wa: weight fraction of monomer A

Tgb: glass transition temperature of homopolymer of monomer B (K) Wb: weight fraction of monomer B

Tgn: glass transition temperature of homopolymer of monomer N (K) Wn: weight fraction of monomer N

(Wa+Wb+...+Wn=1)

The present invention provides an adhesive obtained by crosslinking an adhesive composition for optical members containing the acrylic resin (A) as an essential component. Preferably, the adhesive composition for optical members further contains a crosslinking agent (B), It is an adhesive obtained by crosslinking with a crosslinking agent.

Examples of the crosslinking agent (B) include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, and amine crosslinking agents. agent, metal chelate crosslinking agent. Among these, it is preferable to use an isocyanate crosslinking agent from the viewpoint of improving the adhesiveness with a base material and the reactivity with a base polymer.

Examples of the isocyanate-based crosslinking agent include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hydrogenated toluene diisocyanate, 1,3-xylene diisocyanate, and 1,4-xylene diisocyanate , hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylene Diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, biuret products of these polyisocyanate compounds, isocyanurates acid esters, etc.

Examples of the epoxy-based crosslinking agent include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin Triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether etc.

Examples of the above-mentioned aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide) wait.

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, and hexapentoxymethylmelamine. , hexahexyloxymethyl melamine, melamine resin, etc.

As said aldehyde crosslinking agent, glyoxal, malondialdehyde, succinaldehyde, maleic dialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. are mentioned, for example.

Examples of the amine crosslinking agent include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, Isophorone diamine, amino resin, polyamide, etc.

Examples of the metal chelate crosslinking agent include acetylacetone and acetoacetate complexes of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. compound etc.

In addition, these crosslinking agents (B) may be used alone or in combination of two or more.

The content of the crosslinking agent (B) is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and particularly preferably 0.1 to 2.5 parts by weight relative to 100 parts by weight of the acrylic resin (A). When the crosslinking agent (B) is too small, the cohesive force tends to be insufficient and sufficient durability cannot be obtained. When the crosslinking agent (B) is too large, the flexibility and adhesive force decrease, the durability decreases, and peeling tends to occur, so it is difficult to use as an optical member. Tendency to use.

In this invention, it is preferable to contain a silane coupling agent (C) further as a structural component of the adhesive composition for optical members from a viewpoint of improving the adhesiveness with respect to an optical member.

Examples of the silane coupling agent (C) include epoxy-containing silane coupling agents, (meth)acryloxy-containing silane coupling agents, mercapto-containing silane coupling agents, and hydroxyl-containing silane coupling agents. , Carboxyl-containing silane coupling agent, amino-containing silane coupling agent, amido-containing silane coupling agent, isocyanate-containing silane coupling agent, etc. These may be used alone or in combination of two or more. Among these, it is preferable to use epoxy-containing silane coupling agents and mercapto-containing silane coupling agents, and it is also preferable to use epoxy-containing silane coupling agents in combination from the viewpoint of improving moisture-heat durability and not excessively improving adhesive force. agent and mercapto-containing silane coupling agent.

Specific examples of the above-mentioned epoxy group-containing silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, Oxypropoxypropylmethyldiethoxysilane, γ-Glycidoxypropylmethyldimethoxysilane, Methyltris(glycidyl)silane, β-(3,4-epoxy Cyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Among them, γ-glycidoxypropyltrimethoxysilane, γ - Glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

Specific examples of the above-mentioned mercapto-containing silane coupling agents include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane wait.

The content of the silane coupling agent (C) is usually 0.001 to 10 parts by weight, preferably 0.01 to 1 part by weight, particularly preferably 0.03 to 0.8 parts by weight, based on 100 parts by weight of the acrylic resin (A). When the content of the silane coupling agent (C) is too small, the effect of addition tends not to be obtained, and when it is too large, the compatibility with the acrylic resin (A) tends to decrease, and adhesive force and cohesive force tend not to be obtained .

In the present invention, an unsaturated group-containing compound (D) and a polymerization initiator (E) may also be contained, and the optical member may be bonded by active energy rays and/or heat (active energy ray irradiation and/or heating). agent composition cross-linking.

In the case of the above-mentioned crosslinking by active energy rays and/or heat (active energy ray irradiation and/or heating), an adhesive for optical members containing an unsaturated group-containing compound (D) and a polymerization initiator (E) is used Mixture composition. In this way, by containing the unsaturated group-containing compound (D), crosslinking can be adjusted, and adhesive physical properties suitable for use in optical members can be realized. In addition, by containing the above-mentioned polymerization initiator (E), the reaction at the time of active energy ray irradiation and/or heating can be stabilized.

In the above-mentioned crosslinking, the unsaturated group-containing compound (D) is polymerized (polymerized) by active energy rays and/or heat, and crosslinked with the acrylic resin (A) (physical crosslinking). In the case where the acrylic resin (A) is an unsaturated group-containing acrylic resin, polymerization of the unsaturated group-containing compound (D) by active energy rays and/or heat may also occur This is accompanied by crosslinking such as polymerization of the unsaturated group-containing acrylic resin (A) and the unsaturated group-containing compound (D).

The unsaturated group-containing compound (D) may be a monofunctional unsaturated group-containing compound having one unsaturated group in one molecule, or may have two or more unsaturated groups in one molecule. Polyfunctional unsaturated group-containing compounds, but preferably unsaturated group-containing compounds with more than 2 unsaturated groups, more preferably unsaturated group-containing compounds with more than 3 unsaturated groups, which from the activity It is preferable from the viewpoint of curability when irradiated with energy rays.

As the structure of the above-mentioned unsaturated group-containing compound (D), for example, urethane (meth)acrylate compounds, epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, Compounds, ethylenically unsaturated monomers containing one or more ethylenically unsaturated groups in one molecule, such as monofunctional monomers, difunctional monomers, trifunctional or higher functional monomers, and the like. Among these, use of a urethane (meth)acrylate compound (d1) and an ethylenically unsaturated monomer (d2) is preferable from the viewpoint of excellent curing speed and stability of the achieved physical properties.

The above-mentioned urethane (meth)acrylate compound (d1) is a (meth)acrylate compound having a urethane bond in the molecule, and the (meth)acrylic acid compound containing a hydroxyl group is made by a known common method. What is obtained by reacting a polyisocyanate compound and a polyisocyanate compound (if necessary, a polyol compound) should just be sufficient, and as its weight average molecular weight, the weight average molecular weight of 300-4000 can be used normally.

As the ethylenically unsaturated monomer (d2) used in the present invention, known general monofunctional monomers, difunctional monomers, trifunctional or higher functional monomers, etc. can be used.

The content of the unsaturated group-containing compound (D) is preferably 0.5 to 99 parts by weight, more preferably 1 to 50 parts by weight, and even more preferably 8 to 30 parts by weight, based on 100 parts by weight of the acrylic resin (A). parts by weight. When the content of the above-mentioned unsaturated group-containing compound (D) is too large, the compatibility with the resin tends to decrease and the coating film tends to be whitened. When the content is too small, the crosslinking density of the adhesive becomes insufficient, Light leakage resistance and durability tend to decrease.

As the above-mentioned polymerization initiator (E), for example, various polymerization initiators such as photopolymerization initiator (e1) and thermal polymerization initiator (e2) can be used, and crosslinking can be achieved by irradiation with active energy rays such as ultraviolet rays for a very short time. From the viewpoint of (hardening), it is particularly preferable to use a photopolymerization initiator (e1).

In addition, when the photopolymerization initiator (e1) is used, the adhesive composition for optical members is crosslinked by active energy rays, and when the thermal polymerization initiator (e2) is used, the adhesive composition for optical members is crosslinked by heating. For crosslinking, if necessary, it is also preferable to use both in combination.

The photopolymerization initiator (e1) and the thermal polymerization initiator (e2) are not particularly limited, and known general photopolymerization initiators and thermal polymerization initiators can be used.

The above-mentioned polymerization initiator (E) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 7 parts by weight, more preferably 0.3 to 3 parts by weight, based on 100 parts by weight of the above-mentioned acrylic resin (A). When the content of the above-mentioned polymerization initiator (E) is too small, curability tends to be lacking and physical properties become unstable, and when it is too large, a better effect tends not to be obtained.

Moreover, in the adhesive composition for optical members of this invention, you may further compound other than an antistatic agent, an acrylic adhesive other than an acrylic resin (A), etc. within the range which does not impair the effect of this invention. Adhesives, polyurethane resins, rosin, rosin esters, hydrogenated rosin esters, phenolic resins, aromatic modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins, etc. Conventionally known additives such as tackifiers, colorants, fillers, anti-aging agents, ultraviolet absorbers, functional pigments, and compounds that develop or change color when exposed to ultraviolet rays or radiation.

Moreover, impurities etc. which are contained in the manufacturing raw material of the structural component of the adhesive composition for optical members, etc. may be contained in small quantities other than the said additive.

Examples of the aforementioned antistatic agents include cationic antistatic agents of quaternary ammonium salts such as imidazolium and tetraalkylammonium sulfonates; aliphatic sulfonates, higher alcohol sulfate ester salts, higher alcohol oxidation Anionic antistatic agents such as alkene adduct sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol oxyalkylene adduct phosphate ester salt; bis(fluorosulfonyl)imide potassium, bis(trifluorosulfonyl)acyl Alkali metal salts such as lithium imide and lithium chloride, alkaline earth metal salts, higher alcohol oxyalkylene adducts, polyalkylene glycol fatty acid esters, and the like.

In addition, in the present invention, the adhesive composition for optical members is preferably a composition containing acrylic resin (A) as the main component. Here, "as the main component" means relative to the total amount of the adhesive composition for optical members. , usually contains 50% by weight or more of the acrylic resin (A), preferably 60% by weight or more, more preferably 70% by weight or more. In addition, the upper limit of the content of the acrylic resin (A) is usually 99.9% by weight.

In this way, the adhesive composition for optical members used in the present invention can be obtained, and the adhesive composition for optical members is crosslinked to become the adhesive for optical members of the present invention.

[Adhesives for Optical Members]

In the present invention, the gel ratio of the adhesive for optical members obtained by crosslinking the above-mentioned adhesive composition for optical members is preferably 60 to 95% from the viewpoint of an excellent balance of durability performance and light leakage resistance. , particularly preferably 65 to 90%, more preferably 70 to 85%. When the gel fraction is too low, insufficient durability due to insufficient cohesive force tends to easily occur, and when the gel fraction is too high, the cohesive force tends to increase excessively and peeling tends to occur in a durability test.

In addition, adjusting the gel fraction of the binder to the above-mentioned range can be achieved by, for example, adjusting the type and amount of the crosslinking agent, adjusting the compositional ratio of hydroxyl groups and carboxyl groups in the composition, and the like. In addition, the ratio between the crosslinking agent and the amount of functional groups changes in the gel ratio due to their interaction, and therefore needs to be balanced separately.

The above-mentioned gel ratio is a standard of the degree of crosslinking, and is calculated, for example, by the following method. That is, a 200-mesh SUS metal mesh is used for an adhesive sheet (without a separator) in which an adhesive layer is formed on a polymer sheet (such as polyethylene terephthalate film, etc.) constituting the substrate. Wrapped and dipped in toluene at 23°C for 24 hours, the weight percentage of the undissolved adhesive component remaining in the metal mesh relative to the adhesive layer before dipping in toluene was defined as the gel ratio. Here, the weight of the substrate is subtracted in advance.

The adhesive for optical members of this invention can be used for the optical member conceptually including a display and the optical member which comprises it. As a display, various displays, such as a word processor, a computer, a mobile phone, and a television, are mentioned, and as an optical member, a polarizing plate, the optical laminate based on it, etc. are mentioned. The adhesive for optical members of the present invention has various applications other than the optical member with an adhesive layer described later. In particular, since the adhesive for optical members of the present invention is excellent in reworkability and durability, it is also useful as an adhesive for protective sheets for protecting display screens such as liquid crystal screens. In addition, the adhesive for optical members of the present invention can also be used as an adhesive for temporary surface protection of electronic substrates, an adhesive for double-sided tapes, an adhesive for medical use, an adhesive for surface protection, and ordinary labels. Adhesives, adhesives for sheets used in toys, adhesives for decorative sheets, and adhesives for irregularities.

[Optical member with adhesive layer]

In the present invention, an optical member with an adhesive layer can be obtained by laminating an adhesive layer containing the above-mentioned adhesive for optical members on one or both surfaces of an optical member (for example, an optical laminate).

In the above-mentioned optical member with an adhesive layer, it is preferable that a release sheet is further provided on the surface (exposed surface) opposite to the surface of the adhesive layer on the optical member side.

Moreover, when using the optical member with an adhesive layer for practical use, the said release sheet is peeled and used. Furthermore, it is preferable to use a silicon-based release sheet as the release sheet.

In addition, when producing an optical member with an adhesive layer, as a method of crosslinking the adhesive composition for an optical member, there may be mentioned: [1] coating and drying the adhesive composition for an optical member [2] After coating and drying the adhesive composition for optical members on the release sheet, the method of attaching the optical member and performing aging treatment. Among these, the method of [2] is preferable from the viewpoint of not damaging the optical member, operability, and stable production.

The above-mentioned aging treatment is carried out in order to obtain a balance of adhesive properties. As aging conditions, the temperature is usually room temperature to 70° C., and the time is usually 1 day to 30 days. Specifically, for example, at 23° C. for 1 day to 20 days. Days, 3 days to 10 days at 23°C, and 1 day to 7 days at 40°C may be used.

When applying the above-mentioned adhesive composition for optical members, it is preferable to dilute the adhesive composition for optical members in a solvent to apply, and the diluted concentration is preferably 5 to 60% by weight, particularly preferably 10% by weight. ~30% by weight. In addition, the solvent is not particularly limited as long as it can dissolve the adhesive composition for optical members. For example, ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; acetone, methyl ethyl ketone, etc., can be used. , methyl isobutyl ketone and other ketone solvents; toluene, xylene and other aromatic solvents; methanol, ethanol, propanol and other alcohol solvents. Among these, ethyl acetate and methyl ethyl ketone are suitably used from the viewpoints of solubility, dryness, price, and the like.

Moreover, coating of the said adhesive composition for optical members can be performed by the usual method, such as a roll coater, a die coater, a gravure coater, a comma coater, and screen printing.

In addition, the thickness of the adhesive layer of the obtained optical member with an adhesive layer is usually preferably 5 to 300 μm, particularly preferably 10 to 50 μm, further preferably 12 to 30 μm. When the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive property tends to be difficult to stabilize, and when it is too thick, the thickness of the entire optical member tends to be too thick.

About the optical member with an adhesive layer of this invention, after the optical member which has a release sheet peels off a release sheet, an adhesive layer is bonded to the glass substrate of a liquid crystal cell, for example, and it supplies it to a liquid crystal display device.

The optical member in the optical member with an adhesive layer of the present invention is not particularly limited, and examples thereof include optical films that can be suitably used in image display devices such as liquid crystal display devices, such as polarizing plates, retardation plates, elliptically polarized Sheets, optical compensation films, brightness enhancement films, and optical laminates stacked thereon. Among them, the present invention is particularly effective as a polarizing plate.

The polarizing plate used in the present invention is usually a polarizing plate in which a cellulose triacetate film is laminated as a protective film on both sides of a polarizing film. A film formed of a polyvinyl alcohol-based resin in mole % is used as a raw film, a uniaxially stretched film dyed with an iodine-potassium iodide aqueous solution or a dichroic dye (usually 2 to 10 times, preferably about 3 to 7 times) stretch ratio).

As the above-mentioned polyvinyl alcohol resin, it is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, and may contain a small amount of unsaturated carboxylic acid (including its salt, ester, amide, nitrile, etc.), olefins, Components that can be copolymerized with vinyl acetate, such as vinyl ethers and unsaturated sulfonates. In addition, so-called polyvinyl acetal resins and polyvinyl alcohol derivatives such as polybutyral resins and polyvinyl formal resins obtained by reacting polyvinyl alcohol with aldehydes in the presence of an acid are exemplified.

[Image display device]

The optical member with an adhesive layer of the present invention can be suitably used for image display devices such as liquid crystal display devices, organic EL display devices, PDPs, electronic papers, and LED panels. Even if the image display device containing the optical member with the adhesive layer of the present invention is in a high-temperature, high-humidity environment and repeated environmental changes from low temperature to high temperature, it is difficult to generate a gap between the adhesive layer and the image display device. Lathers, peels. In addition, it is possible to suppress the occurrence of color unevenness and light leakage caused by stress accompanying dimensional changes of optical members such as polarizing plates. Therefore, the display quality of the image display device can be maintained.

Example

The following examples are given to illustrate the present invention more specifically, but the present invention is not limited to the following examples unless the gist of the present invention is exceeded. However, "part" and "%" in an example represent a basis of weight unless otherwise indicated.

First, various acrylic resins (A) were prepared in the following manner. However, the measurement of the weight average molecular weight and the number average molecular weight of the acrylic resin (A) was performed according to the above-mentioned method.

[Preparation of Acrylic Resin (A)]

For Examples 1 to 13, each monomer (a1) to (a5) and 80 parts of ethyl acetate were charged into a four-necked round-bottomed flask equipped with a reflux condenser, a stirrer, a nitrogen blowing port, and a thermometer. Esters, 40 parts of acetone, after heating to reflux, add 0.03 parts of azobisisobutyronitrile as a polymerization initiator, after reacting at the reflux temperature of ethyl acetate for 3 hours, dilute with ethyl acetate to obtain acrylic resins (A ) solution.

For Example 14, put 120 parts of ethyl acetate into a four-necked round-bottomed flask equipped with a reflux condenser, a stirrer, a nitrogen blowing port, and a thermometer, and heat up while stirring. When the internal temperature reaches 75°C, 0.05 parts of azobis Add all the solution of isobutyronitrile (polymerization initiator) dissolved in 5 parts of ethyl acetate, then keep the internal temperature at 74-76°C, add 90.4 parts of butyl acrylate (a1), 8 parts of phenoxydiethyl A mixed solution of diol acrylate (a3), 1 part of 2-hydroxyethyl acrylate (a5), 0.5 part of N-(n-butoxymethyl) acrylamide (a2), and 0.4 part of acrylic acid (a4) was passed through 2 It was added dropwise to the reaction system within hours. Then, after carrying out superposition|polymerization at internal temperature 74-76 degreeC for 5 hours, ethyl acetate was added, and an acrylic resin (A) solution was obtained.

In addition, for Comparative Examples 1 to 3, other copolymerizable monomers (amides or amine compounds) (a5) in the amounts described in Table 1 were added instead of N-(alkoxyalkyl)(meth)acrylamide-based monomers (a2) In Comparative Example 4, except that the monomer (a2) was not added, it carried out similarly to Examples 1-13, and obtained the acrylic resin (A) solution, respectively.

Table 1 shows the weight average molecular weight and number average molecular weight of each acrylic resin (A) solution obtained above.

The monomers indicated by the symbols in Table 1 are as follows.

BA: butyl acrylate

MA: methyl acrylate

BMAA: N-(n-butoxymethyl)acrylamide

MMAA: N-(methoxymethyl)acrylamide

IBMAA: N-(isobutoxymethyl)acrylamide

PEA2: Phenyl diethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Lightacrylate P2HA")

PEA: Phenoxyethyl Acrylate

AAc: acrylic acid

β-CEA: carboxyethyl acrylate (mixture)

HEA: 2-Hydroxyethyl Acrylate

DMAA: Dimethylaminoacrylamide

DMAPAA: Dimethylaminopropylacrylamide

DMAEA: Dimethylaminoethyl Acrylate

[Crosslinking agent (B)]

Prepare the following substance as a crosslinker (B).

・Toluene diisocyanate adduct of trimethylolpropane in 55% ethyl acetate solution (manufactured by Nippon Polyurethane Industry Co., Ltd., "Coronate L-55E") (KL-55E)

[Silane coupling agent (C)]

Prepare the following as a silane coupling agent (C).

・γ-Glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., "X-41-1805")

[antistatic agent]

Prepare potassium bis(fluorosulfonyl)imide (KFSI) as an antistatic agent.

[Examples 1-14, Comparative Examples 1-4]

The respective compounding components prepared and prepared as described above were compounded at the ratios shown in Table 1 to prepare an adhesive composition to be an adhesive-forming material for optical parts, which was diluted with methyl ethyl ketone (viscosity [500 ~1000mPa·s (25°C)]) to prepare an adhesive composition solution.

Next, the above-mentioned adhesive composition solution was coated on a polyester-based release sheet so that the thickness after drying was 25 μm, and after drying at 90° C. for 3 minutes, the side of the formed adhesive composition layer was transferred to After coating on a polyethylene terephthalate (PET) film (thickness 38 μm), it was cured for 10 days at a temperature of 23° C. and a relative humidity of 65% to obtain a PET film with an adhesive layer.

Using the PET film with an adhesive layer obtained in this way, the gel fraction and surface resistivity were measured and evaluated by various methods shown below. These results are shown in Table 2.

[Measuring method of gel fraction]

The obtained PET film with an adhesive layer was cut into a size of 40×40 mm, the release sheet was peeled off, and the adhesive layer side was bonded to a 50×100 mm SUS mesh (200 mesh). After the sample was folded from the central portion relative to the longitudinal direction of the SUS mesh, the gel fraction was measured using the weight change when the sample was immersed in a sealed container containing 250 g of toluene.

[Measuring method of surface resistivity]

After the obtained PET film with an adhesive layer was cut into a size of 40×40 mm, it was left to stand for 3 hours under conditions of a temperature of 23° C.×relative humidity of 65%, and humidity was adjusted. The surface resistivity of the pressure-sensitive adhesive layer after peeling off the release sheet for 10 to 20 seconds was measured using an electrical resistance meter (manufactured by Mitsubishi Chemical Corporation, Hirestar UP). Among them, the smaller the surface resistivity is, the higher the antistatic performance is.

[Preparation of Polarizing Plate with Adhesive Layer]

The adhesive composition solutions of Examples 1 to 14 and Comparative Examples 1 to 4 were coated on a polyester release sheet to a thickness of 25 μm after drying, and after drying at 90° C. for 3 minutes, the formed The adhesive composition layer was transferred onto a polarizing plate (thickness 190 μm), and then aged for 10 days at a temperature of 23° C.×relative humidity of 65%, thereby obtaining a polarizing plate with an adhesive layer.

However, the above-mentioned polarizing plate was cut and used at 45° with respect to the stretching axis.

Using the polarizing plate with an adhesive layer obtained in this way, reworkability, light leakage resistance, and durability (heat resistance test, wet heat resistance test, heat cycle test) were measured and evaluated according to the methods shown below. These results are shown in Table 2.

[reworkability]

The prepared polarizing plate with adhesive layer was cut into a width of 25 mm, the release sheet was peeled off, and the adhesive layer side was pressed against an alkali-free glass plate (manufactured by Corning Inc., EagleXG) to bond the polarizing plate and the glass plate. Then, autoclave treatment (50° C., 0.5 MPa, 20 minutes) was performed, and after 48 hours in an environment of 50° C., it was left in an environment of 23° C. for 30 minutes, and then a 180° peel test was performed. Regarding the reworkability, the adhesive force is desired to be moderately small, and the target is about 10N/25mm after 48 hours. Evaluation was performed according to the following criteria.

(evaluation criteria)

◎: Less than 10N/25mm

○: More than 10N/25mm and less than 15N/25mm

△: More than 15N/25mm and less than 20N/25mm

×: 20N/25mm or more

[light leakage resistance]

After leaving the obtained polarizing plate with an adhesive layer at 80° C. for 1000 hours, a sample for light leakage observation was prepared in which the same sample was bonded on both the front and back sides so that the polarizing plate formed crossed prisms. The backlight was irradiated and visually confirmed, and evaluated according to the following criteria.

(evaluation criteria)

◎: Light leakage was not confirmed at all.

◯: A small amount of light leakage can be confirmed.

Δ: Light leakage can be confirmed to the extent that it may hinder practical use.

X: Light leakage is serious.

[durability]

The release sheet of the obtained polarizing plate with adhesive layer was peeled off, and the adhesive layer side was pressed against an alkali-free glass plate (manufactured by Corning Incorporated, EagleXG). After treatment (50° C., 0.5 MPa, 20 minutes), foaming, peeling, and floating were evaluated in the following durability tests (1) to (3) (heat resistance test, heat and humidity resistance test, heat cycle test). Among them, the size of the test piece used was 20 cm×15 cm.

(1) Heat resistance test

Durability test at 90°C and 2000 hours

(2) Humidity and heat resistance test

Durability test at 60°C, relative humidity (R.H.) 90%, 2000 hours

(3) Thermal cycle test

The operation of standing at -35°C for 30 minutes and then standing at 70°C for 30 minutes is regarded as one cycle, and the durability test is performed for 1000 cycles

[evaluation criteria]

(bubbly)

◎···No foaming

○···Foaming is hardly observed

△···Slight foaming can be observed

×···A lot of foaming can be observed

(stripping)

○···There is less than 0.5mm of peeling, or less than 0.5mm of floating marks

△···There is a peeling of 0.5mm or more and less than 10mm, or a floating mark of 0.5mm or more and less than 10mm

×···There are peelings of 10mm or more, or floating marks of 10mm or more

[Table 1]

[Table 2]

It can be seen that for the polarizing plates with adhesive layers of Examples 1 to 14 containing N-(alkoxyalkyl)(meth)acrylamide-based monomers (a2), the reworkability and property of all can be achieved. A balance of durability when exposed to high temperature and high humidity for a long time.

On the other hand, in the case of using N,N-dialkyl(meth)acrylamide described in Patent Document 2 etc. instead of N-(alkoxyalkyl)(meth)acrylamide monomer (a2) In Comparative Example 1, although the reworkability was excellent, the durability was poor. In addition, Comparative Examples 2 and 3, which used tertiary amino group-containing monomers (acrylate, acrylamide) described in Patent Document 1 or the like instead of the monomer (a2), were inferior in both reworkability and durability. Furthermore, in Comparative Example 4 in which the monomer (a2) was not used, although the reworkability was excellent, the durability was insufficient.

Although this invention was demonstrated in detail with reference to the specific embodiment, it is clear for those skilled in the art that various changes and correction can be added to this invention without deviating from the mind and range of this invention.

This application is based on the JP Patent application (Japanese Patent Application No. 2010-229885) for which it applied on October 12, 2010, The content is taken in here as a reference.

Industrial availability

By using the adhesive composition for optical members of this invention, the adhesive agent for optical members excellent in reworkability and durability can be obtained. Furthermore, by using the adhesive for optical members of this invention, color unevenness and a light leakage phenomenon can be suppressed in image display devices, such as a liquid crystal display panel.

Claims (8)

1. An adhesive composition for an optical member, which is obtained by copolymerizing a copolymerization component [I] mainly composed of an alkyl (meth)acrylate monomer (a1) Acrylic resin (A), and contains N-(alkoxyalkyl)(meth)acrylamide monomer (a2) as copolymerization component [I], N-(alkoxyalkyl)( The content ratio of the meth)acrylamide-based monomer (a2) to the total copolymerization component [I] is 0.1 to 3% by weight, and the adhesive composition for optical members is cross-linked. The gel rate is 60-95%. 2. The adhesive composition for optical members according to claim 1, characterized in that it contains at least one selected from aromatic ring-containing monomers (a3) and carboxyl group-containing monomers (a4) as a copolymerization component [ I]. 3. The adhesive composition for optical members according to claim 1 or 2, which contains a crosslinking agent (B). 4. The adhesive composition for optical members according to claim 1 or 2, which contains a silane coupling agent (C). The adhesive for optical members obtained by crosslinking the adhesive composition for optical members as described in any one of Claims 1-4. 6. The adhesive for optical members according to claim 5, wherein the optical member is a polarizing plate. 7. An optical member with an adhesive layer, characterized in that it comprises a laminated structure of an adhesive layer and an optical member, and the adhesive layer contains the adhesive for optical members according to claim 5 or 6. agent. 8. An image display device comprising the optical member with an adhesive layer according to claim 7.