JP5212688B2 - Optical pressure-sensitive adhesive composition and optical functional film - Google Patents

Description

  The present invention relates to an optical pressure-sensitive adhesive composition used for adhering an optical functional film such as a polarizing plate or a retardation plate to an optical component such as a liquid crystal cell of a liquid crystal display device, and an adhesive formed from the composition. The present invention relates to an optical functional film having an agent layer.

  A liquid crystal cell constituting a liquid crystal display device includes a liquid crystal component oriented in a predetermined direction sandwiched between two glass plates, and an adhesive layer formed from an optical adhesive composition on the outside of these glass substrates. An optical functional film such as a polarizing plate or a laminate of a polarizing plate and a retardation plate is attached. In recent years, liquid crystal display devices have been widely used due to the reduction in weight and thickness of displays for vehicles, outdoor instruments, displays such as personal computers, and televisions, and their demand is increasing. As a result, the usage environment of liquid crystal display devices has become extremely harsh, both indoors and outdoors.

  A polarizing plate used in a liquid crystal display device has a three-layer structure in which both surfaces of a polyvinyl alcohol polarizer are sandwiched between triacetyl cellulose protective films, but has poor dimensional stability due to the characteristics of these materials. In addition, since an optical functional film such as a polarizing plate is formed by stretching, it tends to expand and contract over time. For this reason, in the liquid crystal display device, the internal stress generated by the expansion and contraction of the optical functional film cannot be absorbed and relaxed by the adhesive layer, and the distribution of residual stress acting on the optical functional film becomes non-uniform, In particular, stress concentrates on the peripheral edge. As a result, the peripheral edge of the liquid crystal display device becomes brighter or darker than the center, which causes color unevenness and white spots in the liquid crystal display device.

  Many means have been studied to solve the above problems. For example, in Patent Document 1, a pressure-sensitive adhesive layer made of an acrylic polymer whose main component is an alkyl ester of acrylic acid or methacrylic acid having 1 to 12 carbon atoms in the alkyl group is provided on the surface of the polarizing plate. A pressure-sensitive adhesive layer containing 15% by weight or less of a polymer component having a weight average molecular weight of 100,000 or less and 10% by weight or more of a polymer component having a weight average molecular weight of 1,000,000 or more. A pressure-sensitive adhesive polarizing plate comprising a polymer is disclosed. However, in this invention, since the followability with respect to the shrinkage | contraction of the polarizing plate of an adhesive composition is inadequate, color irregularity and white spot cannot be suppressed.

In Patent Document 2, a high molecular weight (a copolymer of alkyl (meth) acrylate and a polymerizable monomer having a functionality with respect to a crosslinking agent of 0.5 to 20% by weight and having a weight average molecular weight of 1,000,000 or more ( 100 parts by weight of a (meth) acrylic copolymer, 20 to 200 parts by weight of a low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, and a functional group capable of forming a crosslinked structure in the molecule It consists of 0.005 to 5 parts by weight of a polyfunctional compound having at least two, [functional group of low molecular weight (meth) acrylic (co) polymer] / [functionality of high molecular weight (meth) acrylic copolymer] An adhesive composition for a polarizing plate having a functional group distribution ratio represented by the group] in the range of 0 to 15% by weight and a polarizing plate having an adhesive layer formed from the adhesive composition are disclosed. . However, in this invention, since the functional groups of the low molecular weight component are reduced, uneven color and white spots can be suppressed, but durability and reworkability are insufficient.
Japanese Patent No. 2549388 Japanese Patent No. 3533589

  An object of the present invention is a pressure-sensitive adhesive composition used for a liquid crystal cell constituting a liquid crystal display device, which can prevent the occurrence of uneven color and white spots in a liquid crystal display device due to expansion and contraction of an optical functional film, The object is to provide an optical pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer having excellent durability and reworkability.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and found that the above-described object can be achieved by the present invention described below.
That is, the present invention relates to 100 parts by weight of a (meth) acrylic acid ester copolymer (a) having a weight average molecular weight of 800,000 to 2,000,000 and a (meth) acrylic acid ester copolymer having a weight average molecular weight of 50,000 or less. (b) 20 to 100 parts by mass of acrylic acid ester copolymer mixture consisting of (a), becomes from a crosslinking agent (B), the copolymer (a) is, reactivity is high, a hydroxyl group, a carboxyl group and wherein the monomer unit having at least one functional group selected from amino group, the copolymer (b) is a less reactive functional group than the functional group on SL copolymer (a) has Having at least one monomer unit selected from acetoacetoxyethyl (meth) acrylate, vinyl acetoacetate and diacetone acrylamide, wherein the crosslinking agent (B) is an isocyanate To provide an optical pressure-sensitive adhesive composition characterized by, and / or an epoxy-based crosslinking agent.

  In the said invention, the said copolymer (a) contains 0.3-10 mass% of monomer units which have a functional group highly reactive with a crosslinking agent (B); The said copolymer (b ) Preferably contains 0.3 to 10% by mass of a monomer unit having a functional group having low reactivity with the crosslinking agent (B).

In the above present invention, the content of the crosslinking agent, this and a copolymer mixture (A) 0.005 to 3 parts by weight per 100 parts by weight; preferably includes and further silane coupling agent.

  Moreover, this invention provides the optical functional film characterized by having the adhesive layer which consists of an optical adhesive composition of the said invention on the at least one surface.

  Conventionally, in a pressure-sensitive adhesive composition comprising a high molecular weight component, a low molecular weight component, and a crosslinking agent, if there is a functional group in the low molecular weight component, the functional group reacts with the crosslinking agent and the low molecular weight component is crosslinked. Therefore, the effect of stress relaxation caused by the low molecular weight component is lost. Therefore, although the functional group has an effect of increasing the adhesive force and improving the durability, it is necessary to reduce the functional group of the low molecular weight component in order to increase the amount of the low molecular weight component.

  However, in the optical pressure-sensitive adhesive composition of the present invention, a low molecular weight (meth) having a weight average molecular weight of 50,000 or less present together with a high molecular weight (meth) acrylate copolymer having a weight average molecular weight of 800,000 to 2,000,000. Since the acrylic ester copolymer contains functional groups that have low reactivity with the cross-linking agent, these functional groups react only slightly with the cross-linking agent (B), and the stress relaxation effect disappears. There is no end. Furthermore, since the functional group has an effect of increasing durability, deterioration of durability due to the presence of a low molecular weight component can also be prevented. That is, in the optical pressure-sensitive adhesive composition of the present invention, a sufficient amount of a low molecular weight component can be mixed to prevent color unevenness and white spot phenomenon of a liquid crystal display device due to film shrinkage, and the low molecular weight component Since it contains a functional group, it is possible to prevent deterioration of durability and deterioration of reworkability due to the presence of a low molecular weight component.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. The term “(meth) acryl” in the claims and the specification of the present invention means both “acryl” and “methacryl”, and the term “(meth) acrylate” ”And“ methacrylate ”.
The (meth) acrylic acid ester copolymer (a) used in the present invention has a weight average molecular weight of 800,000 to 2,000,000. When the weight average molecular weight of the copolymer (a) is less than 800,000, when the pressure-sensitive adhesive composition is formed and the pressure-sensitive adhesive layer is formed, the durability of the pressure-sensitive adhesive layer becomes insufficient. On the other hand, if the weight average molecular weight of the copolymer (a) exceeds 2 million, it is not preferable because the occurrence of color unevenness and white spot phenomenon is insufficient in the optical functional film.

  The (meth) acrylic acid ester copolymer (a) used in the present invention has the above molecular weight, and the copolymer (a) has a functional group highly reactive with the crosslinking agent (B) described later. It is necessary to include units. Here, “high reactivity with the crosslinking agent (B)” means that the reactivity of the functional group of the copolymer (b) described later is relatively higher than the reactivity with respect to the crosslinking agent. For example, hydroxyl groups and amide groups are such that hydroxyl groups are more reactive with polyisocyanate crosslinking agents. Specific examples of these highly reactive groups include a hydroxyl group, a carboxyl group, and an amino group.

  As the copolymer (a) satisfying the above conditions, an alkyl (meth) acrylate monomer (1) having 1 to 18 carbon atoms and a functional group-containing monomer copolymerizable with the monomer (1) And a copolymer with (2). When the use ratio of the monomer (1) and the monomer (2) is 100% by mass, the monomer (1) is 90 to 99.7% by mass. (2) is preferably 10 to 0.3% by mass. When the amount of the monomer (2) used is less than 0.3% by mass, the durability becomes insufficient when the pressure-sensitive adhesive composition containing the copolymer (a) is used. Further, when the monomer (2) exceeds 10% by mass, the use of the pressure-sensitive adhesive composition containing the copolymer (a) cannot suppress the occurrence of uneven color and white spots in the optical functional film.

  Examples of the monomer (1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth). Examples thereof include alkyl (meth) acrylate monomers such as acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate. These may be used alone or in combination.

  The monomer (2) copolymerized with the monomer (1) is a functional group such as a carboxyl group, hydroxyl group, amino group or substituted amino group, epoxy group or mercapto group having high reactivity with the crosslinking agent (B). A monomer containing a group. Typically, a carboxyl group-containing monomer such as (meth) acrylic acid or carboxyethyl acrylate, or a hydroxyl group-containing monomer such as hydroxyethyl acrylate. These may be used alone or in combination. These monomers (2) are all known in the field of pressure-sensitive adhesive compositions, and any known monomer (2) can be used in the present invention.

  The copolymer (a) can contain a monomer other than the monomer (1) and the monomer (2) as necessary, as long as the effects of the present invention are not impaired. . For example, styrene, methylstyrene, aromatic group-containing monomers such as phenoxyethyl (meth) acrylate or benzyl (meth) acrylate, vinyl acetate, (meth) acrylonitrile, etc. can be contained, and these can be used alone or in combination. May be.

  In the copolymer (a) comprising the above monomers, the content of the monomer (2) unit is 0.3 to 10% by mass when the total monomer units are 100% by mass. It is preferable. If the content of the monomer (2) unit is less than 0.3% by mass, the durability is insufficient. On the other hand, when the content of the monomer (2) unit exceeds 10% by mass, the occurrence of uneven color and white spots is insufficiently suppressed.

  The copolymer (a) satisfying the above conditions can be produced by ordinary solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization or the like, but by solution polymerization in which the copolymer (a) is obtained as a solution. It is preferable to manufacture. By obtaining the copolymer (a) as a solution, it can be used as it is for producing the pressure-sensitive adhesive composition of the present invention. Examples of the solvent used for the solution polymerization include organic solvents such as ethyl acetate, toluene, n-hexane, acetone, and methyl ethyl ketone.

  Examples of the polymerization initiator used in the polymerization include peroxides such as benzoyl peroxide and lauryl peroxide, azobis compounds such as azobisisobutyronitrile and azobisvaleronitrile, and polymer azo polymerization initiators. These can be used alone or in combination. Moreover, in the said superposition | polymerization, in order to adjust the molecular weight of a copolymer (a), a conventionally well-known chain transfer agent can be used.

  The copolymer (b) used in the present invention is a (meth) acrylic acid ester copolymer having a weight average molecular weight of 50,000 or less. As a monomer constituting the copolymer (b), The monomer (1), the monomer (2) and the other monomer, but the monomer (2) is a functional group of the monomer (2) with respect to the crosslinking agent (B). A monomer (2 ′) that is relatively less reactive than the reactivity is used. Examples of such a monomer (2 ′) include monomers having an acetoacetyl group, an active carbonyl group, a mercapto group, an amide group or a substituted amide group, such as acetoacetoxyethyl (meth) acrylate, aceto Examples include vinyl acetate and diacetone acrylamide. These monomers are known per se, and any known monomer can be used.

  In the copolymer (b) comprising the above monomers, the content of the monomer (2 ′) unit is 0.3 to 10% by mass when the total monomer units are 100% by mass. It is preferable to do. If the content of the monomer (2 ') unit is less than 0.3% by mass, the durability is insufficient. On the other hand, when the content of the monomer (2 ′) unit exceeds 10% by mass, the occurrence of uneven color and white spots is insufficiently suppressed.

  In addition, the method for producing the copolymer (b) is to use a large amount of a known chain transfer agent such as a mercaptan compound such as t-octyl mercaptan or an alcohol in order to adjust the weight average molecular weight to 50,000 or less. Is the same as in the case of the copolymer (a). The preferred molecular weight of the copolymer (b) is 1,000 to 50,000, and if the molecular weight is less than 1,000, the durability is insufficient. On the other hand, if the molecular weight exceeds 50,000, the occurrence of uneven color and white spots is insufficiently suppressed.

  The essential resin components in the pressure-sensitive adhesive composition of the present invention are the copolymer (a) and the copolymer (b) described above, and the ratio of both is 100 parts by mass of the copolymer (a). The copolymer (b) needs to be 20 to 100 parts by mass. When the proportion of the copolymer (b) is less than 20 parts by mass, the suppression of the occurrence of uneven color and white spots is insufficient. On the other hand, if the proportion of the copolymer (b) exceeds 100 parts by mass, the durability is insufficient.

  Examples of the crosslinking agent (B) used in the present invention include a polyglycidyl compound having two or more glycidyl groups in one molecule, a polyisocyanate compound having two or more isocyanate groups in one molecule, and aziridinyl in one molecule. A polyaziridine compound having two or more groups, a polyoxazoline compound having two or more oxazoline groups in a molecule, a metal chelate compound or a butylated melamine compound can be used. A polyglycidyl compound, a polyisocyanate compound, or a polyaziridine compound is preferably used in that the durability of the pressure-sensitive adhesive composition can be further improved. These cross-linking agents are all known in the field of pressure-sensitive adhesive compositions, and any known cross-linking agent can be used in the present invention.

  It is preferable that content of the said crosslinking agent (B) is 0.005-3 mass parts with respect to 100 mass parts of acrylic ester copolymer mixture (A), More preferably, it is 0.1-2 mass parts. It is. When the content is less than 0.005 parts by mass, the cohesive force of the pressure-sensitive adhesive composition becomes low, and the durability is inferior compared to the above range. On the other hand, when the amount used exceeds 3 parts by mass, the resulting pressure-sensitive adhesive composition has excessive cohesive strength, which causes peeling of the optical functional film to be adhered.

  Moreover, in this invention, durability of the adhesive layer formed from an adhesive composition can further be improved by containing a silane coupling agent (C). These silane coupling agents are all known in the field of pressure-sensitive adhesive compositions, and any known silane coupling agent can be used in the present invention. It is preferable that content of a silane coupling agent (C) is 0.01-5 mass parts with respect to 100 mass parts of acrylic ester copolymer mixture (A), More preferably, it is 0.1-1 mass. Part. When the content is less than 0.01 parts by mass, the durability is inferior to that within the above range. On the other hand, when the content exceeds 5 parts by mass, the copolymer (a) Although the durability of the toner is improved, the reworkability and the suppression of the occurrence of uneven color and white spots are inferior.

  In the present invention, a known plasticizer can be added to suppress the occurrence of white spots as necessary, and depending on the required properties such as the purpose of adjusting the adhesive strength of the adhesive composition. In addition, various additives may be blended within a range not impairing the effects of the present invention. For example, terpene, terpene-phenol, coumarone-indene, styrene, rosin, xylene, phenol, or petroleum tackifier resins, antioxidants, UV absorbers, fillers, pigments, etc. can do. The production method of the pressure-sensitive adhesive composition of the present invention may be a known method and is not particularly limited, but is preferably in the form of a solution containing an organic solvent. In this case, the pressure-sensitive adhesive layer can be easily formed.

  The optical functional film of the present invention has a pressure-sensitive adhesive layer formed from the optical pressure-sensitive adhesive composition of the present invention on the surface of an optical functional film (raw film) as a substrate.

  Although there is no limitation in particular as the kind of said raw film, For example, a film light-guide plate, an antireflection film, an electroconductive film, a viewing angle expansion film, a phase difference film, a polarizing plate, or the film which combined these etc. are mentioned. . Moreover, in order to improve the adhesiveness with respect to the original film of the said adhesive composition, surface treatments, such as a corona treatment, can be performed to the surface of an original film. Moreover, there is no restriction | limiting in particular in the thickness of the said raw film, Although any thing can be used, For example, the thing of 5-300 micrometers can be used, These differ with uses or the objectives.

  The optical functional film of the present invention is coated by applying the pressure-sensitive adhesive composition of the present invention on one or both sides of the original film using a commonly used coating apparatus such as a roll coating apparatus. It can be produced by drying the layer. If necessary, the pressure-sensitive adhesive layer can be subjected to heat crosslinking or curing with light such as ultraviolet rays. The optical functional film of the present invention is prepared by first applying an adhesive composition to a protective film such as a polyethylene terephthalate film (PET film) coated with a release agent such as a silicone resin and drying the adhesive layer. After forming, it can also be produced by laminating the original film on the pressure-sensitive adhesive layer.

  The coating amount of the pressure-sensitive adhesive composition of the present invention is preferably such that the thickness of the pressure-sensitive adhesive layer after drying is 10 to 50 μm. By setting the thickness of the pressure-sensitive adhesive layer within the above range, an optical functional film having a better balance between durability and reworkability is obtained.

  The above-mentioned optical functional film of the present invention can be stuck on a glass substrate of a liquid crystal display device by means usually used. Further, the optical functional film of the present invention can be further laminated and stuck on the optical functional film stuck on the glass substrate.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited by the following Example, unless the summary is exceeded. In the text, “parts” and “%” are based on mass unless otherwise specified.

  In this example, the value of the weight average molecular weight (MW) is a polystyrene equivalent molecular weight measured by a GPC (GEL Permeation Chromatography) method. Specifically, the coating film obtained by drying the copolymer at room temperature was dissolved in tetrahydrofuran, and measured with a high performance liquid chromatograph (manufactured by Shimadzu Corporation, LC-10ADvp, column KF-G + KF-806 × 2). The weight average molecular weight (MW) in terms of polystyrene was determined.

<Preparation of acrylic copolymer>
[Production Examples A-1 to A-5]
Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen gas. Thereafter, 99 parts of butyl acrylate, 1 part of acrylic acid, 0.1 part of azobisisobutyronitrile and 100 parts of ethyl acetate were added to the reactor. While stirring, this was reacted at 68 ° C. for 8 hours in a nitrogen gas stream. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain a copolymer solution A-1 having a solid content of 20% and a weight average molecular weight of 1.6 million (Production Example 1). The weight average molecular weight was determined in terms of styrene by the GPC method. In the same manner as in Production Example A-1, polymerization was carried out in the same manner with the monomer composition shown in Table 1 to obtain copolymer solutions A-2 to A-5.

[Production Examples B-1 to 6]
After nitrogen gas was sealed in the same reactor as in Production Example 1, ethyl acetate 70 parts, n-hexane 70 parts, methyl ethyl ketone 60 parts, lauryl mercaptan 3 parts, butyl acrylate 97 parts, diacetone acrylamide 3 parts, and azobis Charge 1 part of isobutyronitrile and react at reflux temperature for 10 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate to obtain a copolymer solution B-1 having a solid content of 40% and a weight average molecular weight of 8,000. In the same manner as in Production Example B-1, polymerization was carried out in the same manner with the monomer compositions shown in Table 1 to obtain copolymer solutions B-2 to B-6. In addition, the numerical value of the composition in Table 1 is the number of parts.

ＢＡ： ブチルアクリレート
ＭＡ： メチルアクリレート
ｔ−ＢＡ：ターシャリブチルアクリレート
ＡＡ： アクリル酸
２ＨＥＡ：２−ヒドロキシエチルアクリレート
ＤＡＡＭ：ダイアセトンアクリルアマイド
ＡＡＥＭ：アセトアセトキシエチルアクリレート
ＭＭＡ： メチルメタクリレート

BA: Butyl acrylate MA: Methyl acrylate t-BA: Tertiary butyl acrylate AA: Acrylic acid 2HEA: 2-hydroxyethyl acrylate DAAM: Diacetone acrylamide AAEM: Acetoacetoxyethyl acrylate MMA: Methyl methacrylate

Examples 1-9, Comparative Examples 1-5
The copolymer solutions A-1 and B-1 are mixed so that the solid content ratio is 100 parts: 50 parts, and 0.4 parts of a crosslinking agent and a silane cup are added to 100 parts of the copolymer solution mixture. A pressure-sensitive adhesive composition of Example 1 was obtained by mixing 0.3 part of a ring agent. In the same manner as in Example 1, the components described in Table 2 were mixed to obtain pressure-sensitive adhesive compositions of Examples 2 to 9 and Comparative Examples 1 to 5.

コロネートＬ（商品名） ：日本ポリウレタン工業（株）製、ポリイソシアネート
テトラッドＣ（商品名） ：三菱瓦斯化学（株）製、ポリグリシジル
ＫＢＭ−８０３（商品名）：信越化学工業（株）製、γ−メルカプトプロピルメチルトリメトキシシラン
ＫＢＭ−４０３（商品名）：信越化学工業（株）製、γ−グリシドキシプロピルトリメトキシシラン

Coronate L (trade name): manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate tetrad C (trade name): manufactured by Mitsubishi Gas Chemical Co., Ltd., polyglycidyl KBM-803 (trade name): manufactured by Shin-Etsu Chemical Co., Ltd. γ-mercaptopropylmethyltrimethoxysilane KBM-403 (trade name): manufactured by Shin-Etsu Chemical Co., Ltd., γ-glycidoxypropyltrimethoxysilane

Examples 10-18, Comparative Examples 6-10
Each adhesive composition obtained in Examples 1 to 9 and Comparative Examples 1 to 5 was coated on a silicone resin-coated PET film, and the solvent was removed at 90 ° C. to dry the film. A 25 μm pressure-sensitive adhesive layer was formed. A polarizing plate having a thickness of 180 μm was bonded to the surface on which the pressure-sensitive adhesive layer was formed, and after aging at 23 ° C. for 7 days, optical functional films of Examples 10 to 18 and Comparative Examples 6 to 10 were prepared. Various tests were conducted by the method.

[Durability test]
The optical functional films in Examples 10 to 18 and Comparative Examples 6 to 10 were each cut to 200 mm × 300 mm, and after the PET film was peeled off, it was attached on a glass substrate and subjected to autoclave treatment to produce a sample for evaluation. did. About the obtained sample for evaluation, the test of the following item was performed, respectively. The evaluation results are shown in Table 3.
(1) 80 ° C
The sample for evaluation was allowed to stand in an atmosphere of 80 ° C. (DRY) for 500 hours, and then visually confirmed for foaming and peeling. The evaluation criteria are as follows.
(2) 60 ° C / 95% RH
The sample for evaluation was allowed to stand in an atmosphere of 60 ° C. and 95% RH for 500 hours, and then visually confirmed for foaming and peeling. The evaluation criteria are as follows.

Evaluation criteria (1) Foaming ○: Foaming is not confirmed in the optical functional film.
Δ: Slight foaming was confirmed in the optical functional film (practical level).
X: Foaming was confirmed in the optical functional film.
(2) Peeling ○: Peeling is not confirmed on the optical functional film.
Δ: Slight peeling was confirmed on the optical functional film (practical level).
X: Peeling was confirmed on the optical functional film.

[White spot test]
The same sample after the 80 ° C. endurance test using the optical functional films in Examples 10 to 18 and Comparative Examples 6 to 10 was bonded together in a crossed Nicol state and placed on the backlight of the liquid crystal monitor, and the whitened state Was visually observed.
-Evaluation criteria ○: No white spots were observed in the optical functional film.
Δ: Slight white spots were observed in the optical functional film.
X: White spots were observed in the optical functional film.

[Reworkability test]
Each of the optical functional films in Examples 10 to 18 and Comparative Examples 6 to 10 was cut to 25 mm × 100 mm, and after peeling the PET film, it was attached on a glass substrate, and after autoclaving, 70 ° C./24 hours, After leaving at 23 ° C. for 1 hour, the film was peeled off by hand and the stain on the glass plate was visually evaluated.
○: No dirt on the glass plate and no residual adhesive.
Δ: Slightly stained glass plate and residual adhesive.
X: Stain of glass plate and residual adhesive are remarkable.

  According to the present invention, an optical pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer that absorbs internal stress due to expansion and contraction of an optical functional film and can prevent occurrence of uneven color and white spots in a liquid crystal display device. Can be provided.

Claims (6)

100 parts by weight of a (meth) acrylic acid ester copolymer (a) having a weight average molecular weight of 800,000 to 2,000,000, and a (meth) acrylic acid ester copolymer (b) having a weight average molecular weight of 50,000 or less (b) 20 to 100 Consisting of an acrylic ester copolymer mixture (A) consisting of parts by mass and a crosslinking agent (B),
The copolymer (a) comprises monomer units having at least one functional group selected from the water group, carboxyl group and amino group,
The copolymer (b) comprises A Seto acetoxyethyl (meth) acrylate, the monomer unit is at least one member selected from the acetoacetic acid vinyl and diacetone acrylamide,
An optical pressure-sensitive adhesive composition, wherein the crosslinking agent (B) is an isocyanate-based and / or epoxy-based crosslinking agent. The copolymer (a) is water group, optical pressure-sensitive adhesive of claim 1, wherein the monomer units containing from 0.3 to 10 mass% with at least one functional group selected from carboxyl group and an amino group Agent composition. The copolymer (b) is, A Seth acetoxyethyl (meth) acrylate, according to claim 1 or 2 monomer units is at least one selected from the acetoacetic acid vinyl and diacetone acrylamide containing 0.3 to 10 wt% An optical pressure-sensitive adhesive composition as described in 1.   The optical pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the content of the crosslinking agent is 0.005 to 3 parts by mass per 100 parts by mass of the copolymer mixture (A).   Furthermore, the optical adhesive composition of any one of Claims 1-4 containing a silane coupling agent.   It has an adhesive layer which consists of an optical adhesive composition of any one of Claims 1-5 in an at least one surface, The optical functional film characterized by the above-mentioned.