JP2008101168A - Pressure-sensitive adhesive composition and optical functional film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive composition used for laying and sticking an optical functional film to a substrate e.g., glass and being excellent in both durability and reworkability, which are incompatible properties, and to provide an optical functional film laminated with a pressure-sensitive layer comprising the composition. <P>SOLUTION: The pressure-sensitive adhesive composition comprises (A) an acrylic oligomer-type silane coupling agent prepared by copolymerizing (a) a silane compound having a polymerizable double bond and an alkoxyl group, (b) a functional-group-containing monomer, and (c) a nonfunctional alkyl (meth)acrylate monomer, (B) an acrylic copolymer other than the silane coupling agent (A), and (C) a crosslinking agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adhesive composition and an optical functional film. More specifically, the present invention relates to a pressure-sensitive adhesive composition that is optimal for an optical functional film in a liquid crystal display device, and an optical functional film in which a pressure-sensitive adhesive layer is laminated with the composition.

  The liquid crystal display device has a structure in which a liquid crystal material oriented in a predetermined direction is sandwiched between two glass substrates, and a polarizing plate, a retardation film, a viewing angle expansion film, or the like is provided on the surface of the substrate. The optical functional film is laminated with an adhesive.

  In recent years, this liquid crystal display device has become thinner and larger, and is widely used for various applications such as mounting on vehicles, outdoor instruments, PC displays, or TV displays. There is an increasing trend. With the spread of this application, the environment in which the liquid crystal display device is used has become very harsh. Therefore, the adhesive used for the above-mentioned application does not adhere even when exposed to high temperature or high temperature and high humidity conditions. A characteristic (durability) is required in which foaming does not occur in the agent layer and the attached film does not peel off from the substrate. For this reason, conventionally, an acrylic resin-based adhesive having high adhesive strength has been used as an adhesive for optical functional films, and further improvement in durability is desired.

  By the way, in the manufacturing process of the liquid crystal display device, when a problem occurs in the bonding of the optical functional film, the liquid crystal cell and the liquid crystal material are very expensive. The work which peels and re-sticks is performed. However, since the conventional acrylic resin-based adhesive has a high adhesive strength as described above, it is possible to damage the glass substrate during the above-described peeling, or two sheets filled with liquid crystal components. In many cases, the gap width of the glass substrate is changed, and the glass substrate cannot be used again. In addition, even if the film is peeled off, a part of the pressure-sensitive adhesive remains on the glass substrate or the like, and there is a problem that the operation of re-attaching the optical functional film cannot be performed.

  Thus, in addition to the durability as described above, the adhesive used for the optical functional film can be easily peeled off even after a long time has passed since the optical functional film was attached. Moreover, the characteristic (rework property) that an adhesive does not remain on a glass substrate etc. is required after peeling.

  In order to solve the above problems, Patent Document 1 proposes a pressure-sensitive adhesive composition in which a specific amount of a specific polymer-type silane coupling agent is contained in an acrylic polymer. However, since the main chain of the silane coupling agent is a polysiloxane skeleton, the affinity with the acrylic polymer is not sufficient, and the composition does not have sufficient durability due to phase separation. . Patent Document 2 proposes a pressure-sensitive adhesive composition in which a specific amount of a specific silane compound monomer is contained in an acrylic polymer. However, in the composition, the silane compound monomer is liberated and the durability is not sufficient with time.

Japanese Patent No. 3498158 Japanese Patent No. 3533446

  An object of the present invention is a pressure-sensitive adhesive composition for laminating and sticking an optical functional film on a substrate such as glass of a liquid crystal display device, which has excellent durability and reworkability, which are contradictory properties. It is another object of the present invention to provide an adhesive composition and an optical functional film in which an adhesive layer is laminated with the composition.

  In order to solve the above problems, the present inventors have conducted extensive research and found that the following problems can be solved by the present invention. That is, the present invention copolymerizes a silane compound (a) having a polymerizable double bond group and an alkoxy group, a functional group-containing monomer (b), and a non-functional alkyl (meth) acrylate monomer (c). A pressure-sensitive adhesive comprising an acrylic oligomer-type silane coupling agent (A), an acrylic copolymer (B) other than the silane coupling agent (A), and a crosslinking agent (C) A composition is provided.

  Moreover, in the said adhesive composition, silane coupling agent (A) is molar ratio 1: 0.02: 0.02-1: of silane compound (a), monomer (b), and monomer (c). 40:40 copolymer, preferably having a weight average molecular weight of 1,000 to 20,000 and a dispersity (MW / MN) of 1.0 to 2.0. It is preferable that content of a ring agent (A) is 0.05-5 mass parts with respect to 100 mass parts of acrylic copolymers (B).

  The pressure-sensitive adhesive composition comprises an acrylic copolymer (B) having a C1-C18 alkyl (meth) acrylate monomer (d) and a functional group-containing monomer copolymerizable with the monomer (d). It is a copolymer with (e), and it is preferable that the weight average molecular weight of this copolymer is 800,000-2 million, and content of a crosslinking agent (C) is acrylic copolymer ( B) It is preferable that it is 0.01-5 mass parts with respect to 100 mass parts.

  The pressure-sensitive adhesive composition may further contain a silane coupling agent (D) other than the silane coupling agent (A). In this case, the content of the silane coupling agent (D) It is preferable that it is 0.01-3 mass parts with respect to 100 mass parts of acrylic copolymers (B).

  Moreover, this invention provides the optical functional film characterized by laminating | stacking the adhesive composition of this invention on the single side | surface or both surfaces.

  According to the present invention, an adhesive composition for laminating and attaching an optical functional film on a substrate such as glass of a liquid crystal display device, which has excellent durability and reworkability, which are contradictory properties An adhesive composition and an optical functional film in which an adhesive layer is laminated with the composition can be provided.

Next, the present invention will be described in detail with reference to the best mode for carrying out the invention.
The pressure-sensitive adhesive composition of the present invention comprises a specific acrylic oligomer type silane coupling agent (A) (hereinafter sometimes simply referred to as “silane coupling agent (A)”), and an acrylic other than the silane coupling agent. It contains a copolymer (B) and a crosslinking agent (C). Since the adhesive composition of this invention contains the specific silane coupling agent (A) mentioned later, while improving durability, it has the outstanding rework property.

  The specific silane coupling agent (A) that characterizes the present invention will be described. The silane coupling agent (A) includes a silane compound (a) having a polymerizable double bond group and an alkoxy group, a functional group-containing monomer (b), a non-functional alkyl (meth) acrylate monomer (c), Is a compound obtained by copolymerization. For this reason, since the main chain is a carbon skeleton, the silane coupling agent has good affinity with the acrylic copolymer (B), and since it is an oligomer type, the silane compound monomer may be liberated. Absent. 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 silane coupling agent (A) is a copolymer having a molar ratio of the silane compound (a), the monomer (b), and the monomer (c) of 1: 0.02: 0.02 to 1:40:40. Preferably, the polymer has a weight average molecular weight (MW) of 1,000 to 20,000 and a dispersity (MW / MN) of 1.0 to 2.0. Furthermore, the molar ratio is more preferably 1: 0.03: 0.03 to 1:35:35. When the above-described molar ratio, weight average molecular weight, and degree of dispersion are within the above ranges, the pressure-sensitive adhesive composition of the present invention is more excellent in durability and reworkability. The term “MN” in the claims and specification of the present invention means “number average molecular weight”.

  The silane compound (a) is a compound having a polymerizable double bond group that is copolymerized with the monomer (b) and the monomer (c), and an alkoxy group that is a functional group for an inorganic substance such as a glass substrate. Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxy Examples thereof include propyltriethoxysilane, and at least one selected from these groups can be used.

  The monomer (b) includes a carboxyl group, a hydroxyl group, an acetyl group, an amide group or a substituted amide group, an amino group or a substituted amino group, and an epoxy group that are reactive with the copolymer (B) and the crosslinking agent (C) described later. Or it is a monomer containing functional groups, such as a mercapto group, The following are mentioned as a specific example, At least 1 sort (s) chosen from these groups can be used.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, carboxyethyl (meth) acrylate, and the like. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and caprolactone-modified (meth) acrylate. Glycerol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, N- (2-hydroxyethyl) acrylamide and the like. Examples of the acetyl group-containing monomer include vinyl acetoacetate, allyl acetoacetate, allyl diacetoacetate, diacetone acrylamide, acetoacetoxymethyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, acetoacetoxyethyl crotonate, Examples include acetoacetoxypropyl (meth) acrylate, acetoacetoxypropyl crotonate, acetoacetoxybutyl (meth) acrylate, and the like. Examples of the amide group or substituted amide group-containing monomer include (meth) acrylamide, N-methylol (meth) acrylamide, Nn-butoxymethylacrylamide, Ni-butoxymethylacrylamide, N, N-dimethylacrylamide, N -Methyl acrylamide etc. are mentioned. Examples of the amino group or substituted amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and the like. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, glycidyl (meth) allyl ether, 3,4-epoxycyclohexyl (meth) acrylate, and the like. Examples of the mercapto group-containing monomer include allyl mercaptan. In particular, a monomer having an acetyl group is preferable.

  The monomer (c) has an alkyl group that is highly compatible (affinity) with the acrylic copolymer (B). For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl ( Monomers such as (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, and the like. At least one selected from the group can be used.

  The silane coupling agent (A) obtained by copolymerizing the structural units can be produced by ordinary solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, or the like. The silane coupling agent (A) Is preferably produced by solution polymerization obtained as a solution. By obtaining the silane coupling agent (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 silane coupling agent (A), a chain transfer agent can be used. For example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its ester, 2-ethylhexylthioglycol, thioglycol Mercaptans such as octyl acid; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol and allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane and trichlorethylene; acetone , Methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde carbonyls such as n-butyraldehyde, furfural, benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, α-methylstyrene, etc., and at least one selected from these groups should be used. Can do. A chain transfer agent having a mercapto group is preferable.

  The content of the silane coupling agent (A) in the pressure-sensitive adhesive composition of the present invention is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer (B). When the content is less than 0.05 parts by mass, the adhesive strength of the copolymer (B) cannot be appropriately reduced, and the reworkability is inferior compared with the above range, When the content exceeds 5 parts by mass, the adhesive strength of the copolymer (B) is reduced, but the durability is inferior compared with the above range.

  The acrylic copolymer (B), which is the main component of the pressure-sensitive adhesive composition of the present invention, is a cohesive copolymer obtained by copolymerizing an acrylic monomer and a functional group-containing monomer. Preferably, it is a copolymer of an alkyl (meth) acrylate monomer (d) having 1 to 18 carbon atoms and a functional group-containing monomer (e) copolymerizable with the monomer (d), and the copolymer The weight average molecular weight is preferably 800,000 to 2,000,000. When the weight average molecular weight is less than 800,000, the cohesive force of the formed pressure-sensitive adhesive layer is weak even when the cross-linking agent (C) is used, and the pressure-sensitive adhesive layer is easily foamed or peeled, resulting in poor durability. May be sufficient. On the other hand, when the weight average molecular weight exceeds 2 million, the viscosity of the pressure-sensitive adhesive composition becomes too high and the workability is poor.

  Examples of the monomer (d) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Examples include alkyl (meth) acrylate monomers such as octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate, and at least one selected from these groups can be used. .

  The monomer (e) has a functional group for an organic substance such as a cross-linking agent (C) or a raw film, such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid or carboxyethyl (meth). Carboxyl group-containing monomers such as acrylate, acid anhydride monomers such as maleic anhydride or fumaric anhydride, N- (2-hydroxyethyl) (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Hydroxyl group such as acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, caprolactone modified (meth) acrylate, polyethylene glycol mono (meth) acrylate or polypropylene glycol mono (meth) acrylate Yes monomers, amino group-containing monomers such as dimethylaminoethyl (meth) acrylate, include an amide group-containing monomers such as (meth) acrylamide, it can be used at least one selected from these groups.

  The proportion of the monomer (d) or the monomer (e) in the copolymer (B) is such that the copolymer (B) comprises only the monomer (d) and the monomer (e). Assuming that the monomer (d) is 90 to 99.8% by mass, the monomer (e) is preferably 0.2 to 10% by mass, and more preferably the monomer (d) is 93 to 99.5 mass%, the said monomer (e) is 0.5-7.0 mass%. When the monomer (d) is less than 90% by mass (when the monomer (e) exceeds 10% by mass), the pressure-sensitive adhesive layer to be formed has high hardness, and the adhesion to the optical functional film is within the above range. It is inferior to the inside. On the other hand, when the monomer (d) exceeds 99.8% by mass (when the monomer (e) is less than 0.2% by mass), it reacts with the crosslinking agent (C) in the copolymer (B). When there are few functional groups and the degree of crosslinking decreases, the cohesive force of the pressure-sensitive adhesive composition becomes weak, and the durability is inferior compared with the above range.

  The said copolymer (B) can contain monomers other than the said monomer (d) and the said monomer (e) as needed in the range which does not impair the effect of this invention. For example, aromatic group-containing monomers such as styrene, methylstyrene, phenoxyethyl (meth) acrylate or benzyl (meth) acrylate, vinyl acetate, (meth) acrylonitrile and the like can be contained, and these can be used alone or in combination. Good.

  The acrylic copolymer (B) obtained by copolymerizing the above monomers can be produced by ordinary solution polymerization, bulk polymerization, emulsion polymerization or suspension polymerization, and is preferably solution polymerization. As the solvent or polymerization initiator used in the solution polymerization, those similar to the solution polymerization in the silane coupling agent (A) can be used, and a chain transfer agent can be used in combination.

  Examples of the crosslinking agent (C) constituting 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. The cross-linking agent (C) reacts with the functional group of the copolymer (B) to increase the cohesive strength of the pressure-sensitive adhesive composition, and also reacts with the reactive functional group of the silane coupling agent (A). A bonding force is developed between the silane coupling agent (A) and the copolymer (B).

  Examples of the polyglycidyl compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexane. Diol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol poly Polyfunctional glycidyl compounds such as glycidyl ether can be used, and at least one selected from these groups can be used.

  Examples of the polyisocyanate compound include tolylene diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and prepolymers modified from these, and at least one selected from these groups is used. Can be used.

  Examples of the polyaziridine compound include 1,1 ′-(methylene-di-p-phenylene) bis-3,3-aziridylurea, 1,1 ′-(hexamethylene) bis-3,3-aziridylurea, Ethylenebis- (2-aziridinylpropionate), tris (1-aziridinyl) phosphine oxide, 2,4,6-triaziridinyl-1,3,5-triazine, trimethylolpropane-tris- (2-aziridinini) Lupropionate) and the like, and at least one selected from these groups can be used.

  It is preferable that content of the said crosslinking agent (C) is 0.01-5 mass parts with respect to 100 mass parts of said copolymers (B), More preferably, it is 0.02-4 mass parts. . When the said content is less than 0.01 mass part, the cohesion force of an adhesive composition becomes low and durability is inferior compared with the said range. On the other hand, when the amount used exceeds 5 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, the adhesive composition of this invention can contain silane coupling agents (D) other than the said silane coupling agent (A) further. By containing the silane coupling agent (D), the durability of the composition can be further improved. The content of the silane coupling agent (D) is preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the acrylic copolymer (B).

  A well-known thing can be used for the said silane coupling agent (D). For example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4- Epoxycyclohexyl) ethyltrimethoxysilane, epoxy group-containing silane coupling agent such as epoxy group-containing alkoxysilane oligomer, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltrimethyldimethoxysilane, γ- Mercapto group-containing silane coupling agents such as mercaptopropyltrimethyldiethoxysilane, mercapto group-containing alkoxysilane oligomers, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxy Sisilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyl Examples include amino group-containing silane coupling agents such as dimethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane, and isocyanate group-containing silane coupling agents such as γ-isocyanatopropyltrimethoxysilane and γ-isocyanatopropyltriethoxysilane. And at least one selected from these groups can be used.

  Moreover, the adhesive composition of this invention may mix | blend various additives in the range which does not impair the effect of this invention according to required characteristics, such as the objective of adjusting adhesive force. For example, terpene, terpene-phenol, coumarone indene, styrene, rosin, xylene, phenol, or petroleum tackifier resins, antioxidants, UV absorbers, fillers, pigments, etc. can do. The pressure-sensitive adhesive composition of the present invention 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 is characterized in that the pressure-sensitive adhesive composition of the present invention is laminated on one side or both sides of an optical functional film (raw film) on which no pressure-sensitive adhesive layer is formed. For this reason, the optical functional film of the present invention does not peel off from the glass substrate or the like even under high temperature or high temperature and high humidity, and does not cause foaming in the pressure-sensitive adhesive layer (durability), and has a long time. It can be easily peeled off even after a lapse of time, and also has a property (reworkability) that does not cause residue on the substrate after peeling.

  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 micrometers-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. Moreover, 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 values of the weight average molecular weight (MW) and the number average molecular weight (MN) are polystyrene equivalent molecular weights 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 silane coupling agent A>
[Production Example 1]
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, 80 parts of butyl acrylate, 10 parts of γ-methacryloxypropyltrimethoxysilane, 10 parts of acetoacetoxyethyl acrylate, 10 parts of triethylene glycol dimercaptan, 0.3 part of azobisisobutyronitrile and 100 parts of toluene was added. While stirring, this was reacted at 90 ° C. for 8 hours in a nitrogen gas stream. After completion of the reaction, the reaction solution was diluted with toluene to obtain a silane coupling agent solution A-1 having a solid content of 40%, a weight average molecular weight of 3,000, and a dispersity of 1.3.

[Production Example 2]
Except for changing the blending amount of triethylene glycol dimercaptan in Production Example 1 from 10 parts to 3 parts, in exactly the same manner as in Production Example 1, the solid content is 40%, the weight average molecular weight is 10,000, and the dispersity is 1.7. Silane coupling agent solution A-2 was obtained.

[Production Example 3]
Except that 10 parts of triethylene glycol dimercaptan of Production Example 1 was changed to 0.5 part of lauryl mercaptan, 40% solid content, weight average molecular weight of 50,000, and dispersity of 2.5 were the same as Production Example 1. A silane coupling agent solution A-3 was obtained.

[Production Example 4]
Production Example, except that the blending amounts of butyl acrylate, γ-methacryloxypropyltrimethoxysilane, and acetoacetoxyethyl acrylate in Production Example 1 were changed from 80 parts to 50 parts, 10 parts to 30 parts, and 10 parts to 20 parts, respectively. In the same manner as in Example 1, a silane coupling agent solution A-4 having a solid content of 40%, a weight average molecular weight of 2,900, and a dispersity of 1.2 was obtained.

[Production Example 5]
Production Example except that the blending amounts of butyl acrylate, γ-methacryloxypropyltrimethoxysilane, and acetoacetoxyethyl acrylate in Production Example 1 were changed from 80 parts to 20 parts, 10 parts to 40 parts, and 10 parts to 40 parts, respectively. In the same manner as in Example 1, a silane coupling agent solution A-5 having a solid content of 40%, a weight average molecular weight of 3,000, and a dispersity of 1.3 was obtained.

[Production Example 6]
Production Example, except that the blending amounts of butyl acrylate, γ-methacryloxypropyltrimethoxysilane, and acetoacetoxyethyl acrylate in Production Example 1 were changed from 80 parts to 50 parts, 10 parts to 1 part, and 10 parts to 49 parts, respectively. In the same manner as in Example 1, a silane coupling agent solution A-6 having a solid content of 40%, a weight average molecular weight of 3,200, and a dispersity of 1.3 was obtained.

[Production Example 7]
Except for changing the blending amounts of butyl acrylate, γ-methacryloxypropyltrimethoxysilane and acetoacetoxyethyl acrylate in Production Example 1 from 80 parts to 0.5 parts, 10 parts to 99 parts, and 10 parts to 0.5 parts, respectively. Produced silane coupling agent solution A-7 having a solid content of 40%, a weight average molecular weight of 3,100, and a dispersity of 1.3 in exactly the same manner as in Production Example 1.

<Preparation of acrylic copolymer B>
[Production Example 8]
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, 94 parts of butyl acrylate, 5 parts of acrylic acid, 1 part of 2-hydroxyethyl acrylate, 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 reaction mixture was diluted with ethyl acetate to obtain a copolymer solution B-1 having a solid content of 20%, a weight average molecular weight of 1,300,000 and a viscosity of 2,000 mPa · s.

<Production and evaluation of pressure-sensitive adhesive composition and optical functional film>
[Example 1]
0.4 parts (solid content) of silane coupling agent solution A-1 with respect to 100 parts of solid content of copolymer solution B-1, and polyisocyanate (trade name: Coronate L, Japan) as crosslinking agent C Polyurethane Industry Co., Ltd.) 0.2 parts (solid content) was added and mixed to obtain a pressure-sensitive adhesive composition of Example 1.

  Next, the obtained pressure-sensitive adhesive composition of Example 1 was applied on a PET film coated with a silicone resin, and the solvent was removed at 90 ° C., followed by drying and a cross-linking reaction, thereby causing a pressure-sensitive adhesive having a thickness of 25 μm. A layer was formed. A polarizing plate having a thickness of 250 μm was bonded to the surface on which the pressure-sensitive adhesive layer was formed to produce an optical functional film. After this optical functional film was cured at 23 ° C. and 50% RH for 7 days, the durability test and the reworkability test were evaluated by the test methods described later. The evaluation results were good in all items. The evaluation results are shown in Table 2.

[Examples 2 to 7]
As shown in Table 1, the pressure-sensitive adhesive compositions and optical functional films of Examples 2 to 7 were prepared in exactly the same manner as in Example 1 except that the types and / or amounts of the silane coupling agent and the crosslinking agent were changed. Obtained. The evaluation results were good in all items. The evaluation results are shown in Table 2.

[Example 8]
The pressure-sensitive adhesive composition and optical functional film of Example 8 were the same as Example 1 except that the amount of the silane coupling agent solution A-1 of Example 1 was changed from 0.4 part to 10 parts. Were prepared and evaluated. As a result of the evaluation, peeling occurred slightly in the durability test, but it was at a level where there was no practical problem. The evaluation results are shown in Table 2.

[Example 9]
Except that the silane coupling agent solution A-1 in Example 1 was changed to A-3, the pressure-sensitive adhesive composition and the optical functional film of Example 9 were produced in the same manner as in Example 1, and evaluated. went. In the reworkability test, the evaluation result showed that peeling was heavy, but it was at a level where there was no practical problem. The evaluation results are shown in Table 2.

[Example 10]
Except that the silane coupling agent solution A-1 of Example 1 was changed to A-6, the pressure-sensitive adhesive composition and optical functional film of Example 10 were produced in the same manner as in Example 1, and evaluated. went. As a result of the evaluation, peeling occurred slightly in the durability test, and peeling was heavy in the reworkability test. The evaluation results are shown in Table 2.

[Example 11]
Except that the silane coupling agent solution A-1 of Example 1 was changed to A-7, the pressure-sensitive adhesive composition and optical functional film of Example 11 were prepared in the same manner as in Example 1, and evaluated. went. As a result of the evaluation, peeling occurred slightly in the durability test, and peeling was heavy in the reworkability test. The evaluation results are shown in Table 2.

[Example 12]
Example 1 except that 0.2 part of γ-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the silane coupling agent solution A-1 of Example 1. The pressure-sensitive adhesive composition and optical functional film of Example 12 were produced and evaluated in exactly the same manner. The evaluation results were good in all items. The evaluation results are shown in Table 2.

[Comparative Example 1]
Except not using silane coupling agent solution A-1 of Example 1, the adhesive composition and optical functional film of Comparative Example 1 were produced and evaluated in exactly the same manner as in Example 1. . As a result of evaluation, peeling occurred in the durability test. In the reworkability test, peeling after heating was very heavy, and a slight amount of adhesive residue was confirmed. The evaluation results are shown in Table 2.

[Comparative Example 2]
The silane coupling agent solution A-1 of Example 1 was changed to γ-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), and the addition amount was 0.2 parts. Except that, the pressure-sensitive adhesive composition and the optical functional film of Comparative Example 2 were produced and evaluated in the same manner as in Example 1. As a result of the evaluation, in the reworkability test, peeling after heating was very heavy, and a lot of adhesive residue was confirmed. The evaluation results are shown in Table 2.

※表1に記載した「テトラッドＸ」は、三菱瓦斯化学（株）製の商品名を示し、ポリグリシジル化合物である。
※表１に記載した「ＫＢＭ−４０３」は、シランカップリング剤（Ａ）以外のシランカップリング剤であるが、便宜上同じ欄に記載した。

* “Tetrad X” shown in Table 1 represents a product name manufactured by Mitsubishi Gas Chemical Co., Ltd., and is a polyglycidyl compound.
* "KBM-403" described in Table 1 is a silane coupling agent other than the silane coupling agent (A), but is described in the same column for convenience.

<Test methods and evaluation criteria>
[Durability test]
The optical functional films in Examples and Comparative Examples were each cut to 200 mm × 300 mm, and after the PET film was peeled off, it was affixed on a glass substrate and subjected to autoclave treatment to produce an evaluation sample. About the obtained sample for evaluation, the test of the following item was performed, respectively.
-Heat durability test The sample for evaluation was allowed to stand in an atmosphere of 90 ° C (DRY) for 500 hours, and then visually confirmed for foaming and peeling. The evaluation criteria are as follows.
-Humidification durability test The sample for evaluation was allowed to stand for 500 hours in an atmosphere of 60 ° C and 95% RH, 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.

[Reworkability test]
-Peelability test Each of the optical functional films of Examples and Comparative Examples was peeled off by 180 ° according to JIS Z0237 (initial adhesive strength: adhesive strength after standing at 23 ° C for 1 hour). In the same manner, the optical functional films of Examples and Comparative Examples were each allowed to stand at 70 ° C. for 3 hours, then allowed to cool to 23 ° C., and then left to stand at this temperature for 1 hour (heating adhesive strength). ) Was measured. A glass plate was used as the adherend. In this test, the lower the adhesive strength of both, the better the peelability.
-Adhesive residue test After measuring the said heating adhesive force, the residue (adhesive residue) of the adhesive composition to the glass substrate surface was confirmed visually. The evaluation criteria are as follows.
Evaluation criteria (1) Adhesive residue ○: Adhesive residue is not confirmed on the glass substrate surface.
Δ: A slight amount of adhesive residue was confirmed on the glass substrate surface (practical level).
X: Adhesive residue was confirmed on the surface of the glass substrate.

  According to the present invention, an adhesive composition for laminating and attaching an optical functional film on a substrate such as glass of a liquid crystal display device, which has excellent durability and reworkability, which are contradictory properties An adhesive composition and an optical functional film in which an adhesive layer is laminated with the composition can be provided. Therefore, the pressure-sensitive adhesive composition and the optical functional film of the present invention can be suitably used for liquid crystal display devices.

Claims (8)

  Acrylic oligomer type obtained by copolymerizing a silane compound (a) having a polymerizable double bond group and an alkoxy group, a functional group-containing monomer (b), and a non-functional alkyl (meth) acrylate monomer (c). A pressure-sensitive adhesive composition comprising a silane coupling agent (A), an acrylic copolymer (B) other than the silane coupling agent (A), and a crosslinking agent (C).   The silane coupling agent (A) is a copolymer having a molar ratio of the silane compound (a), the monomer (b), and the monomer (c) of 1: 0.02: 0.02 to 1:40:40, The pressure-sensitive adhesive composition according to claim 1, having a weight average molecular weight of 1,000 to 20,000 and a dispersity (MW / MN) of 1.0 to 2.0.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of the silane coupling agent (A) is 0.05 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer (B).   The acrylic copolymer (B) is a copolymer of an alkyl (meth) acrylate monomer (d) having 1 to 18 carbon atoms and a functional group-containing monomer (e) copolymerizable with the monomer (d). The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the copolymer has a weight average molecular weight of 800,000 to 2,000,000.   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the content of the crosslinking agent (C) is 0.01 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer (B). .   Furthermore, the adhesive composition of any one of Claims 1-5 containing silane coupling agents (D) other than a silane coupling agent (A).   The pressure-sensitive adhesive according to any one of claims 1 to 6, wherein the content of the silane coupling agent (D) is 0.01 to 3 parts by mass with respect to 100 parts by mass of the acrylic copolymer (B). Composition.   An optical functional film obtained by laminating the pressure-sensitive adhesive composition according to any one of claims 1 to 7 on one side or both sides.