JP2013194151A - Tacky adhesive sheet, optical film with tacky adhesive and optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tacky adhesive sheet which has a short aging time from when a tacky adhesive composition is coated into a sheet-like shape till when processing such as cutting can be performed on the sheet without difficulty, and which has excellent processability, and to apply the tacky adhesive sheet to an optical film with a tacky adhesive and to an optical laminate.SOLUTION: A tacky adhesive sheet is formed into a sheet-like shape from a tacky adhesive composition containing: an acrylic resin (A) being a copolymer obtained from a monomer mixture containing 75-99.9 wt.% of the (meth)acrylic acid alkyl ester (A-1) shown by formula (I): CH=C(R)-CO-ORand 0.1-5 wt.% of a (meth)acrylic monomer (A-2) having a carboxyl group; a cross-linking agent (B) comprising an isocyanate compound having an aromatic ring and at least two isocyanate groups in a molecule; and a (meth)acrylate monomer (C) containing the carboxyl group, which is shown by formula (II): CH=C(R)-CO-O-A-COOH (wherein A is a 2-4C bivalent organic group).

Description

  The present invention relates to an adhesive sheet suitably used for an optical film, and an optical film with an adhesive formed by bonding the adhesive sheet to an optical film. The optical film targeted in the present invention includes, for example, a polarizing plate and a retardation film. The present invention also relates to an optical laminate in which this optical film with an adhesive is laminated on a glass substrate and is suitably used for liquid crystal display.

  A polarizing plate is widely used by being mounted on a liquid crystal display device. A polarizing plate generally has a transparent protective film laminated on both sides of a polarizing film, a pressure-sensitive adhesive layer is formed on the surface of at least one protective film, and a release film is stuck on the pressure-sensitive adhesive layer. doing. In addition, a retardation film is laminated on a polarizing plate in which a protective film is bonded to both sides of the polarizing film to form an elliptical polarizing plate, and an adhesive layer / release film is attached in this order to the retardation film side. Sometimes. Furthermore, an adhesive layer / release film may be stuck in this order on the surface of the retardation film. In this specification, the polarizing plate, the elliptically polarizing plate, the retardation film and the like provided with the pressure-sensitive adhesive layer are collectively referred to as an optical film. The optical film provided with these pressure-sensitive adhesive layers is cut into a predetermined size, peeled off the release film before being bonded to the liquid crystal cell, and bonded to the liquid crystal cell via the exposed pressure-sensitive adhesive layer. An optical film provided with such a pressure-sensitive adhesive layer has a problem of workability that the pressure-sensitive adhesive layer tends to be chipped during cutting. For this reason, after forming the pressure-sensitive adhesive layer, it is generally cured and used for a sufficient period of time, and there is still room for improvement in terms of productivity.

  The pressure-sensitive adhesive applied to the optical film is manufactured by copolymerizing a monomer having an acrylic ester as a main component and a polar functional group such as a hydroxyl group or a carboxyl group from the viewpoint of transparency and weather resistance. Many acrylic resins are used. By blending such an acrylic resin with a crosslinking agent, the required cohesive force is imparted. Here, the crosslinking agent is a compound having in the molecule at least two functional groups capable of forming a crosslinked structure by reacting with a polar functional group constituting the acrylic resin. Specifically, an isocyanate compound or an epoxy compound is used. Compounds, metal chelate compounds, amine compounds, and the like. Of these, isocyanate compounds are widely used as crosslinking agents.

  That is, by blending an acrylic resin having a polar functional group with an isocyanate-based crosslinking agent having at least two isocyanato groups (—NCO) in the molecule, the functional group in the acrylic resin becomes an isocyanate group in the crosslinking agent over time. Reacts with to form a cross-linked structure, develops cohesive force and improves processability. Therefore, if the speed of the cross-linking reaction is increased, the time required to show sufficient processability can be shortened. As a means for increasing the speed of the crosslinking reaction, for example, paragraph 0046 of Japanese Patent No. 4370888 (Patent Document 1) describes that an amine compound is blended as a crosslinking catalyst. It is said that a compound based on this type is suitable.

  JP-A-2009-173772 (Patent Document 2) discloses a pressure-sensitive adhesive for optical members that exhibits good processability by blending an acrylic resin having a hydroxyl group with a silane compound having an amino group and an isocyanate-based crosslinking agent. It has been proposed to provide an agent composition. Furthermore, JP-A-2009-215528 (Patent Document 3) discloses an isocyanate-based cross-linking agent and a silane coupling to an acrylic resin having an aromatic ring and a small amount of an amino group, and additionally having a carboxyl group and / or a hydroxyl group. It has been proposed that a pressure-sensitive adhesive composition for an optical film that also exhibits good processability is formulated by blending an agent.

  In addition to the amine compounds described above, organotin compounds such as dibutyltin dilaurate and aluminum complexes are effective as a crosslinking catalyst for the reaction of an acrylic copolymer having a hydroxyl group or a carboxyl group with an isocyanate crosslinking agent. It is known. On the other hand, JP 2011-1440 (Patent Document 4) considers the effects of organotin compounds and aluminum complexes on the human body to increase the reactivity of the isocyanate-based crosslinking agent without using them. In addition, the use of β-diketones, typically acetylacetonate complexes of iron, ruthenium, zinc or zirconium, has been proposed.

  In this way, if a silane compound having an amino group or an acrylic resin having an amino group is used as a component of the pressure-sensitive adhesive composition or a metal compound-based cross-linking catalyst is blended, the cross-linking reaction of the pressure-sensitive adhesive is promoted. However, the presence of an amino group, which is a functional group different from the isocyanato group, or the presence of a metal compound having a different functional group may depend on the environment in which the adhesive is used. An unpredictable reaction may occur at the time of use. In this case, there is a problem that the performance of the pressure-sensitive adhesive is changed.

  On the other hand, an optical film with an adhesive is bonded to a liquid crystal cell on the adhesive layer side to form a liquid crystal panel. In this state, the optical film is placed in a high temperature or high temperature and high humidity condition, and heating and cooling are repeated. If the dimensional change of the optical film occurs, foaming will occur in the pressure-sensitive adhesive layer, or there may be floating or peeling between the optical film and the pressure-sensitive adhesive layer or between the pressure-sensitive adhesive layer and the liquid crystal cell glass. Therefore, it is required to have excellent durability without causing such problems. In particular, when an acrylic resin having a carboxyl group or a hydroxyl group, which is the main component of the pressure-sensitive adhesive layer, contains a compound having a significantly different chemical structure and a low compatibility, such as a metal compound, the compatibility is low. The compound often precipitates and leads to defects such as foaming, floating, and peeling, and in this case, durability is impaired.

  In addition, when the optical film with adhesive is placed in a high temperature environment, the distribution of residual stress acting on the optical film becomes non-uniform, and stress concentration occurs on the outer periphery of the optical film, resulting in the outer periphery becoming whitish when displaying black. Since a phenomenon called white spotting or color unevenness may occur, suppression of such white spotting or color unevenness is also required. In addition, when there is a defect when an optical film with an adhesive is bonded to a liquid crystal cell, the optical film is peeled off and then a new film is reattached. A so-called rework property is also required in which the agent layer is peeled off along with the optical film, no adhesive remains on the cell glass, and no fogging occurs.

Japanese Patent No. 4370888 (Japanese Patent Laid-Open No. 2004-190012) JP 2009-173772 A JP 2009-215528 A Japanese Unexamined Patent Publication No. 2011-1440

  The object of the present invention is to provide a pressure-sensitive adhesive sheet that has a short curing time and is excellent in workability before it can be processed without problems after being coated in a sheet shape. The optical film with pressure-sensitive adhesive is applied, and the optical film with pressure-sensitive adhesive is further bonded to a glass substrate having a liquid crystal cell as a representative example to form an optical laminate.

  As a result of intensive studies to solve such problems, the present inventors have obtained by copolymerization of (meth) acrylic acid ester as a main component and a (meth) acrylic monomer having a carboxyl group. A pressure-sensitive adhesive composition in which a specific isocyanate-based crosslinking agent and a (meth) acrylic acid ester monomer having a carboxyl group at a position away from a carbon-carbon double bond site are blended with an acrylic resin to be obtained, By including the carboxyl group-containing (meth) acrylic acid ester monomer of the specific structure, it will show a high gel fraction in a short curing time after coating in a sheet shape, and it has excellent workability and agglomeration It was found that a pressure-sensitive adhesive sheet exhibiting excellent durability can be obtained by the development of force. The pressure-sensitive adhesive composition for forming this pressure-sensitive adhesive sheet does not contain a compound or resin having an amino group, nor a metal compound-based crosslinking catalyst, while containing a carboxyl group having the above-mentioned specific structure blended therein ( The (meth) acrylic acid ester monomer has a similar chemical structure to the (meth) acrylic acid ester constituting the acrylic resin that is the main component of the pressure-sensitive adhesive composition, and therefore does not change its performance in various usage environments. It has been found that an adhesive sheet is provided. The present invention has been completed based on such findings.

  That is, the pressure-sensitive adhesive sheet of the present invention comprises (meth) acrylic acid ester (A-1) 75 to 99.9% by weight and (meth) acrylic monomer (A-2) 0. An acrylic resin (A) which is a copolymer obtained from a monomer mixture containing 1 to 5% by weight, a crosslinking agent (B) comprising an isocyanate compound having an aromatic ring and at least two isocyanato groups in the molecule, and The sheet is formed from a pressure-sensitive adhesive composition containing a carboxyl group-containing (meth) acrylic acid ester monomer (C) shown below.

The (meth) acrylic acid ester (A-1) is represented by the following formula (I), wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 14 or less carbon atoms. .

The carboxyl group-containing (meth) acrylic acid ester monomer (C) is represented by the following formula (II), where R ₃ represents a hydrogen atom or a methyl group, and A is a C 2-4 carbon atom. Represents a divalent organic group.

  The pressure-sensitive adhesive composition forming this pressure-sensitive adhesive sheet can further contain a silane compound (D).

  In general, these pressure-sensitive adhesive sheets are preferably formed on a plastic film, and a typical example of the plastic film in that case is a release film subjected to a release treatment. And it is often produced in a state where the pressure-sensitive adhesive sheet is formed on the release film, that is, in a state where the release film is stuck on one surface of the pressure-sensitive adhesive sheet. A release film can also be attached to the other surface.

  The optical film with a pressure-sensitive adhesive of the present invention is one in which any one of the above pressure-sensitive adhesive sheets is bonded to the optical film. This optical film advantageously includes at least one of a polarizing plate and a retardation film.

  Moreover, the optical laminated body of this invention is a thing with which said optical film with an adhesive is laminated | stacked on the glass substrate by the adhesive sheet side.

  The pressure-sensitive adhesive sheet of the present invention comprises an acrylic resin (A) having a carboxyl group as a main component and an isocyanate compound having an aromatic ring as a crosslinking agent (B), and further containing the above-mentioned carboxyl group-containing (meth) acrylic acid. It forms from the adhesive composition with which the ester monomer (C) was mix | blended. Thus, the isocyanate compound which has an aromatic ring is employ | adopted as a crosslinking agent (B) with respect to the acrylic resin (A) which has a carboxyl group, and also the carboxyl group containing (meth) acrylic acid ester monomer (C) is mix | blended. By forming a pressure-sensitive adhesive sheet from the pressure-sensitive adhesive composition, the crosslinking reaction proceeds quickly, and the curing time from application of the pressure-sensitive adhesive composition to a sheet shape until high gel fraction is shortened, processing The property is improved.

  Moreover, the optical film with an adhesive of this invention gives the optical laminated body for liquid crystal displays, for example by laminating | stacking on the glass substrate of a liquid crystal cell. In this optical laminate, the pressure-sensitive adhesive sheet absorbs and relaxes stress caused by the dimensional change of the optical film and the glass substrate under high-temperature conditions, wet heat conditions, or in an environment where heating and cooling are repeated. Stress concentration is reduced, and the pressure-sensitive adhesive layer is prevented from floating or peeling off from the glass substrate.

It is a cross-sectional schematic diagram which shows the example of the suitable layer structure of the optical laminated body which concerns on this invention.

  The present invention will be described in detail below. The pressure-sensitive adhesive sheet of the present invention comprises an acrylic resin (A) copolymerized with a (meth) acrylic monomer (A-2) having a carboxyl group, and a crosslinking agent (B) comprising a diisocyanate compound having an aromatic ring. And a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester monomer (C) having a carboxyl group at the alcohol residue site forming the ester. First, each of these components constituting the pressure-sensitive adhesive composition will be described.

[Acrylic resin (A)]
The acrylic resin (A) constituting the pressure-sensitive adhesive composition is mainly composed of the (meth) acrylic acid ester (A-1) represented by the above formula (I) and further having a carboxyl group. It is a copolymer obtained from a monomer mixture containing a monomer (A-2). Here, (meth) acrylic acid means that either acrylic acid or methacrylic acid may be used, and “(meth)” such as (meth) acrylate has the same meaning. In this specification, the (meth) acrylic acid ester (A-1) represented by the formula (I) is simply referred to as “monomer (A-1)” and a (meth) acrylic monomer having a carboxyl group. The body (A-2) may be simply referred to as “monomer (A-2)”.

In the above formula (I), which is the main structural unit of the acrylic resin (A), R ₁ is a hydrogen atom or a methyl group, and R ₂ is an alkyl group having 14 or less carbon atoms.

  Specific examples of the monomer (A-1) include linear acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, and lauryl acrylate. Alkyl acrylates; branched alkyl acrylates such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacryl Illustrative are linear alkyl methacrylates such as n-octyl acid and lauryl methacrylate; and branched alkyl alkyl esters such as isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate. Is done. These monomers (A-1) can be used alone or in combination with a plurality of different monomers.

  Among these, n-butyl acrylate is preferable. Specifically, among all the monomers constituting the acrylic resin (A), n-butyl acrylate is 50% by weight or more and is described above. It is preferable to use it so as to satisfy the regulations regarding the monomer (A-1).

  The monomer (A-2) is a (meth) acrylic monomer having a carboxyl group, typically acrylic acid or methacrylic acid, but other than the above, such as 2-carboxyethyl acrylate, The carboxyl group-containing (meth) acrylic acid ester corresponding to the formula (II) can also be the monomer (A-2). Among these, it is preferable to use acrylic acid as one of the monomers (A-2) constituting the acrylic resin (A).

  In the acrylic resin (A), the content of the structural unit derived from the (meth) acrylic acid ester represented by the formula (I), that is, the monomer (A-1) is 75 to 99.9% by weight, The content of the structural unit derived from the (meth) acrylic monomer having a carboxyl group, that is, the monomer (A-2) is 0.1 to 5% by weight. By copolymerizing the monomers (A-1) and (A-2) in such a limited ratio, a pressure-sensitive adhesive composition that gives a pressure-sensitive adhesive sheet with excellent processability can be obtained. The content of the structural unit derived from the monomer (A-1) is preferably 99.5% by weight or less. The content of the structural unit derived from the monomer (A-2) is preferably 0.5% by weight or more, and preferably 4% by weight or less, especially 3% by weight or less. Of course, the total amount of structural units derived from each of the monomers (A-1) and (A-2) does not exceed 100% by weight.

  The acrylic resin (A) is essentially derived from the structural units derived from the monomers (A-1) and (A-2) described above, but the other monomers are copolymerized and derived therefrom. It may contain a structural unit. Examples of suitable monomers that can be copolymerized in addition to the monomers (A-1) and (A-2) include (meth) acrylic acid esters other than the above formula (I), particularly the following formula (III) ) A substituted alkyl ester of (meth) acrylic acid represented by

Here, R ₄ represents a hydrogen atom or a methyl group, X represents an alkylene group having 14 or less carbon atoms, m represents 0 or an integer of 1 to 4, n represents 0 or 1, and R ₅ represents carbon. An alkyl group or an aryl group having a number of 12 or less is represented, and when n is 0, R ₅ represents an aryl group.

The substituted alkyl ester of (meth) acrylic acid represented by the above formula (III) will be described. In the formula (III), X is an alkylene group having 14 or less carbon atoms, and the alkylene group preferably has about 1 to 4 carbon atoms, and when n is 0, the alkylene group represented by X The number of carbon atoms is preferably about 2 to 4. m is 0 or an integer of 1 to 4, but 0, 1 or 2 is particularly preferable. R ₅ is an alkyl group or aryl group having 12 or less carbon atoms, and may be linear or branched as long as the alkyl group has 3 or more carbon atoms. Examples of the aryl group constituting R ₅ include phenyl and naphthyl, as well as nuclear alkyl-substituted phenyl including tolyl, xylyl, ethylphenyl, and biphenylyl (or phenylphenyl). R ₅ is particularly preferably these aryl groups.

In the formula (III), examples of the compound where n is 0 include benzyl acrylate and benzyl methacrylate. When n is 0, the rightmost alcohol residue site constituting the ester of formula (III) is —X—R ₅ , and when R ₅ is an alkyl group, it is represented by the formula (I) ( It overlaps with (meth) acrylic acid ester. Thus, when n is 0, R ₅ cannot be an alkyl group and is therefore an aryl group.

  Examples of compounds in which m is 0 and n is 1 in formula (III) include 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, and 2- (o -Alkoxyalkyl or aryloxyalkyl esters of acrylic acid, such as -phenylphenoxy) ethyl; 2-methoxyethyl methacrylate, ethoxymethyl methacrylate, 2-phenoxyethyl methacrylate, and 2- (o-phenylphenoxy) methacrylate There are alkoxyalkyl esters or aryloxyalkyl esters of methacrylic acid, such as ethyl.

  Examples of compounds in which m is 1 and n is 1 in formula (III) include aryloxyethoxyalkyl esters of acrylic acid such as 2- (2-phenoxyethoxy) ethyl acrylate; methacrylic acid 2 There are aryloxyethoxyalkyl esters of methacrylic acid such as-(2-phenoxyethoxy) ethyl.

  It is effective that the substituted alkyl ester of (meth) acrylic acid represented by the above formula (III) is copolymerized at a ratio of 15% by weight or less based on all monomers constituting the acrylic resin (A). .

  In addition, for example, a monomer having a polar functional group other than a carboxyl group, a (meth) acrylic acid ester other than those represented by formulas (I) and (III), and having an alicyclic structure in the molecule ( A (meth) acrylic acid ester, a styrene monomer, a vinyl monomer, a (meth) acrylamide derivative, a monomer having a plurality of (meth) acryloyl groups in the molecule, and the like can also be copolymerized.

  A monomer having a polar functional group other than a carboxyl group will be described. Here, the polar functional group other than the carboxyl group may be a heterocyclic group including an epoxy ring. Examples of the monomer having a heterocyclic group include acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl. There are (meth) acrylate, glycidyl (meth) acrylate, and the like.

  When a monomer having a polar functional group other than a carboxyl group is copolymerized, the acrylic resin (A) is added, including the (meth) acrylic monomer (A-2) having a carboxyl group as an essential component. The total of monomers having polar functional groups is preferably 5% by weight or less, more preferably 4% by weight or less, and particularly preferably 3% by weight or less, based on the total monomers constituting the composition.

  The (meth) acrylic acid ester having an alicyclic structure in the molecule will be described. The alicyclic structure is a cycloparaffin structure having usually 5 or more carbon atoms, preferably about 5 to 7 carbon atoms. Examples of acrylates having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, tert-butyl acrylate Examples include cyclohexyl, α-ethoxyacrylate cyclohexyl, cyclohexylphenyl acrylate, and the like. Examples of methacrylic acid esters having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, tert methacrylate. -Butyl cyclohexyl, cyclohexyl phenyl methacrylate and the like.

  Examples of styrenic monomers include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene. Alkyl styrenes; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, and the like.

  Examples of vinyl monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate and vinyl laurate such as vinyl esters; vinyl halides such as vinyl chloride and vinyl bromide; Vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile, methacrylonitrile, etc. .

  Examples of (meth) acrylamide derivatives include N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (4- Hydroxybutyl) (meth) acrylamide, N- (5-hydroxypentyl) (meth) acrylamide, N- (6-hydroxyhexyl) (meth) acrylamide, N- (methoxymethyl) (meth) acrylamide, N- (ethoxymethyl) ) (Meth) acrylamide, N- (propoxymethyl) (meth) acrylamide, N- (butoxymethyl) (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N- Isopropyl (meth) acrylamide, N- (3-di Tilaminopropyl) (meth) acrylamide, N- (1,1-dimethyl-3-oxobutyl) (meth) acrylamide, N- [2- (2-oxo-1-imidazolidinyl) ethyl] (meth) acrylamide, 2- And acryloylamino-2-methyl-1-propanesulfonic acid.

  Examples of monomers having a plurality of (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonane. Two diols in the molecule, such as diol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate A monomer having a (meth) acryloyl group; and a monomer having three (meth) acryloyl groups in the molecule, such as trimethylolpropane tri (meth) acrylate.

  (Meth) acrylic acid ester and styrene monomer having an alicyclic structure in the molecule other than the monomers (A-1) and (A-2) which are essential components of the acrylic resin (A) When a monomer having no polar functional group such as a vinyl monomer, a (meth) acrylamide derivative, or a monomer having a plurality of (meth) acryloyl groups in the molecule is copolymerized, the ratio is acrylic resin Based on the total monomers constituting (A), it is usually preferred to be 5% by weight or less, more preferably 3% by weight or less, and particularly preferably 1% by weight or less.

  The resin component constituting the pressure-sensitive adhesive composition is the (meth) acrylic acid ester represented by the formula (I) described above, that is, the monomer (A-1), and the (meth) acrylic monomer having a carboxyl group. Two or more types of acrylic resins (A) each having a structural unit derived from a monomer, that is, the monomer (A-2) may be mixed. Further, an acrylic resin different from the acrylic resin (A) having structural units derived from the monomers (A-1) and (A-2) at a predetermined ratio may be mixed. Examples of the different acrylic resins mixed in this case include those having a structural unit derived from the (meth) acrylic acid ester of the formula (I) and having no polar functional group. The acrylic resin (A) having a predetermined proportion of structural units derived from the monomers (A-1) and (A-2) is 80% by weight or more, and further 90% by weight or more of the whole acrylic resin. It is preferable to do so.

  The acrylic resin (A) obtained by copolymerization of the monomer mixture containing the monomers (A-1) and (A-2) is a weight average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC). Mw is preferably in the range of 500,000 to 2,000,000. The weight average molecular weight Mw is more preferably 500,000 to 1,800,000. When the weight average molecular weight in terms of standard polystyrene is 500,000 or more, the adhesiveness under high temperature and high humidity is improved, and the possibility of occurrence of floating or peeling between the glass substrate and the pressure sensitive adhesive sheet is reduced. And reworkability tends to be improved. In addition, when the weight average molecular weight is 2 million or less, even if the dimension of the optical film bonded to the pressure-sensitive adhesive sheet changes, the pressure-sensitive adhesive layer changes following the dimensional change. This is preferable because there is no difference between the brightness of the peripheral portion and the brightness of the central portion, and white spots and color unevenness tend to be suppressed. The molecular weight distribution represented by the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn is not particularly limited, but is preferably in the range of about 3 to 7, for example.

  The acrylic resin (A) preferably has a glass transition temperature in the range of −10 to −60 ° C. in order to develop adhesiveness. The glass transition temperature of the resin can be measured by a differential scanning calorimeter.

  The acrylic resin (A) can be produced by various known methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method. In the production of this acrylic resin, a polymerization initiator is usually used. The polymerization initiator is used in an amount of about 0.001 to 5 parts by weight with respect to a total of 100 parts by weight of all monomers used in the production of the acrylic resin.

  As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, or the like is used. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone. Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis (2-methylpropio) And azo compounds such as 2,2'-azobis (2-hydroxymethylpropionitrile); lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroper Oxide, diisopropylperoxydicarbonate, dipropylperoxydicarbonate, tert-butylperoxide Organic peroxides such as xineodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl) peroxide; inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide An oxide etc. can be mentioned. A redox initiator using a peroxide and a reducing agent in combination can also be used as the polymerization initiator.

  Among the methods shown above, the solution polymerization method is preferable as the method for producing the acrylic resin. A specific example of the solution polymerization method will be described. A desired monomer and an organic solvent are mixed, a thermal polymerization initiator is added under a nitrogen atmosphere, and about 40 to 90 ° C, preferably 50 to 80 ° C. A method of stirring at about C for about 3 to 15 hours can be mentioned. Moreover, in order to control reaction, you may add a monomer and a thermal-polymerization initiator continuously or intermittently during superposition | polymerization, or may be added in the state melt | dissolved in the organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; acetone, methyl ethyl ketone, and methyl isobutyl. Ketones such as ketones can be used.

[Crosslinking agent (B)]
In the present invention, an isocyanate compound having an aromatic ring and at least two isocyanato groups (—NCO) in the molecule is blended in the acrylic resin (A) described above as a crosslinking agent (B). Specific examples of this isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Two or more isocyanate compounds may be mixed and used.

  An isocyanate compound having at least two isocyanato groups in the molecule is, for safety and health reasons, an adduct having a urethane bond formed by addition reaction of a isocyanate group at one end to a polyol such as glycerol or trimethylolpropane, It is often used in a dimer or trimer form, that is, in a high molecular weight form. For example, in the trimer of a diisocyanate compound having two isocyanato groups in the molecule, the diisocyanate compound in which three molecules of the diisocyanate compound form an isocyanurate ring at the portion of each isocyanato group, There are burettes in which molecules are bonded by hydration and decarboxylation at each isocyanato group at one end. Such a high molecular weight of an isocyanate compound can of course be used as the crosslinking agent (B), but it is more preferable.

  In the present invention, tolylene diisocyanate, xylylene diisocyanate, or those having a high molecular weight as described above are preferably used as the crosslinking agent (B).

  A crosslinking agent (B) is normally mix | blended in the ratio of 0.01-5 weight part with respect to 100 weight part of acrylic resins (A). The amount of the crosslinking agent (B) is preferably 0.1 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). When the blending amount of the crosslinking agent (B) with respect to 100 parts by weight of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.1 parts by weight or more, the durability of the pressure-sensitive adhesive sheet tends to be improved. It is preferable that the amount is 5 parts by weight or less because white spots are not noticeable when the optical film with an adhesive is applied to a liquid crystal display device.

[Carboxyl group-containing (meth) acrylic acid ester monomer (C)]
In the present invention, a carboxyl group-containing (meth) acrylic acid ester monomer (C) is further blended into the pressure-sensitive adhesive composition. This carboxyl group-containing (meth) acrylic acid ester monomer (C) is represented by the formula (II), and as can be seen from this formula, the carboxyl group is located at a position away from the carbon-carbon double bond site by a predetermined number of atoms. Have In this formula (II), R ₃ is a hydrogen atom or a methyl group, and A is a divalent organic group having 2 to 4 carbon atoms. The divalent organic group represented by A is typically alkylene, which is also preferably linear alkylene, but the (meth) acrylic acid moiety CH ₂ ═C (R ₃ ) COO— Assuming that the carbon chain connecting the terminal carboxyl group —COOH is at least 2 in series, the chain may be branched if it has 3 or more carbon atoms. Of these, acrylic acid esters are preferable, and specific examples include 2-carboxyethyl acrylate, 3-carboxypropyl acrylate, 4-carboxybutyl acrylate, and the like. Of course, the compound which changed these acrylic acid ester into the methacrylic acid ester can also become a carboxyl group-containing (meth) acrylic acid ester monomer (C).

  2-Carboxyethyl acrylate is usually produced by dimerization of acrylic acid. In that case, in addition to 2-carboxyethyl acrylate, which is the main component, acrylic acid itself and oligomers of trimers of acrylic acid or more. In many cases, it is sold as a mixture as it is. Thus, together with the carboxyl group-containing (meth) acrylic acid ester (C) represented by the formula (II), other carboxyl group-containing (meth) acrylic monomers are present in the pressure-sensitive adhesive composition. Of course.

  The carboxyl group-containing (meth) acrylic acid ester monomer (C) is preferably blended in an amount of 0.004 parts by weight or more, more preferably 0.02 parts by weight or more, based on 100 parts by weight of the acrylic resin (A). Is done. When the blending amount of the carboxyl group-containing (meth) acrylic acid ester monomer (C) is 0.004 parts by weight or more, particularly 0.02 parts by weight or more with respect to 100 parts by weight of the acrylic resin (A), the adhesive It is preferable because the processability of the agent sheet tends to be improved. On the other hand, even if the amount is too large, the effect of improving the workability of the pressure-sensitive adhesive sheet is saturated, and this carboxyl group-containing (meth) acrylic acid ester alone is also obtained by drying after coating in a sheet form The body (C) cannot be removed and may remain in the pressure-sensitive adhesive sheet as a low-molecular free acid, affecting the physical properties thereof. Therefore, the upper limit of the amount is preferably about 1 part by weight with respect to 100 parts by weight of the acrylic resin (A).

[Silane Compound (D)]
The pressure-sensitive adhesive sheet of the present invention can contain a silane compound (D). In that case, what is necessary is just to mix | blend a silane compound (D) with the adhesive composition for forming an adhesive sheet. Thereby, after setting it as an optical film with an adhesive, the adhesiveness of the adhesive sheet and a glass substrate can be improved. The silane compound (D) may be contained in the acrylic resin before blending the crosslinking agent.

  The silane compound (D) can be a compound in which at least one hydrolyzable alkoxy group and another organic group are bonded to a silicon atom. For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane 3-glycidoxypropyldimethylethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane , 3-mercaptopropyltrimethoxysilane and the like. Two or more silane compounds may be used.

  The silane compound (D) may be of a silicone oligomer type. When the silicone oligomer is shown in the form of (monomer)-(monomer) copolymer, for example, the following can be mentioned.

  3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxy A copolymer containing a mercaptopropyl group, such as a silane copolymer;

  Mercaptomethyl groups such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer. Containing copolymers;

  3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-Methacryloyloxypropylmethyldiethoxysilane-tetra Toki bell Ranco polymers such as, methacryloyloxypropyl group containing copolymers;

  3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane Rimmer such as, acryloyloxypropyl group-containing copolymer;

  Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, Vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer.

  These silane compounds are often liquids. The compounding quantity of the silane compound (D) in an adhesive composition is about 0.01-10 weight part normally with respect to 100 weight part of acrylic resins (A), Preferably it is 0.02 weight part, Furthermore, Preferably it is used in a ratio of 0.03 to 1 part by weight. When the blending amount of the silane compound (D) with respect to 100 parts by weight of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.03 parts by weight or more, adhesion between the pressure-sensitive adhesive sheet and the glass substrate is improved. To preferred. Further, the blending amount is preferably 10 parts by weight or less, particularly 2 parts by weight or less, or 1 part by weight or less because the so-called bleed-out of the silane compound from the pressure-sensitive adhesive sheet tends to be suppressed.

[Other explanation about pressure-sensitive adhesive composition]
The pressure-sensitive adhesive composition may further contain dyes, pigments, inorganic fillers, crosslinking catalysts, antistatic agents, weathering stabilizers, tackifiers, plasticizers, softeners, resins other than the acrylic resin (A), and the like. It is also useful to blend an ultraviolet curable compound into this pressure-sensitive adhesive composition and to cure it by irradiating with ultraviolet rays after forming the pressure-sensitive adhesive sheet to form a harder pressure-sensitive adhesive layer.

  When the pressure-sensitive adhesive composition is used as a pressure-sensitive adhesive sheet, it is preferable that the pressure-sensitive adhesive composition does not contain an amino group in order to avoid a strong adhesion with a specific release film. In particular, it is preferable not to have a tertiary amino group.

  These components constituting the pressure-sensitive adhesive composition described above are mixed in a state dissolved in a solvent to prepare a pressure-sensitive adhesive composition in a solution state. Some components may be dispersed without dissolving in the solvent.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention is formed into a sheet form from the pressure-sensitive adhesive composition described above. Specifically, the pressure-sensitive adhesive composition prepared in the above solution state is applied on a suitable substrate and dried to form a pressure-sensitive adhesive sheet. The substrate used here is generally a plastic film, and a typical example thereof is a release film that has been subjected to a release treatment. The release film is, for example, a film on which a pressure-sensitive adhesive sheet of a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarylate is formed and subjected to a release treatment such as silicone treatment. Can be. A pressure-sensitive adhesive sheet may be formed on the release film, and another release film may be attached to the exposed surface of the resulting pressure-sensitive adhesive sheet. That is, the pressure-sensitive adhesive sheet of the present invention can take a form in which a release film is attached to at least one surface.

  As mentioned above, this pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive composition containing the carboxyl group-containing (meth) acrylic acid ester monomer (C) represented by the formula (II). It is characterized in that the cross-linking reaction proceeds rapidly after coating, and shows a relatively high gel fraction value in a shorter curing time compared to the case where it is not included. Since the carboxyl group-containing (meth) acrylic acid ester monomer (C) represented by the formula (II) is only mixed in the pressure-sensitive adhesive composition, the solvent is removed by drying unless the amount is too large. In this stage, it is removed together with the solvent and hardly remains in the pressure-sensitive adhesive sheet.

The gel fraction is a value measured according to the following (1) to (4).
(1) An adhesive sheet having an area of about 8 cm × about 8 cm and a metal mesh made of SUS304 (with a weight of Wm) of about 10 cm × about 10 cm are bonded.
(2) Weigh the bonded product obtained in (1) above, weigh it Ws, then fold it 4 times so as to wrap the adhesive sheet, weigh it with a stapler (stapler), weigh it, Let the weight be Wb.
(3) The mesh stapled in (2) above is placed in a glass container, and 60 mL of ethyl acetate is added and immersed, and then the glass container is stored at room temperature for 3 days.
(4) The mesh is taken out from the glass container, dried at 120 ° C. for 24 hours, weighed, the weight is taken as Wa, and the gel fraction is calculated based on the following formula.
Gel fraction (% by weight) = [{Wa− (Wb−Ws) −Wm} / (Ws−Wm)] × 100

  In many cases, the pressure-sensitive adhesive sheet is used after being cured until the crosslinking reaction in the pressure-sensitive adhesive layer has sufficiently progressed so that the gel fraction can be processed without any problem. The state in which this crosslinking reaction has proceeded, that is, the gel fraction at the end of curing, depends on, for example, the type of acrylic resin (A), which is an active ingredient of the pressure-sensitive adhesive composition, and the type and blending amount of the crosslinking agent (B). Can be adjusted. Specifically, the amount of the monomer (A-2) in the acrylic resin (A) and the other monomer having a polar functional group is increased, or the crosslinking agent (B) in the pressure-sensitive adhesive composition. If the blending amount is increased, the gel reaction can be increased because the crosslinking reaction proceeds faster.

[Optical film with adhesive]
The optical film with pressure-sensitive adhesive of the present invention is obtained by bonding a pressure-sensitive adhesive sheet formed from the above pressure-sensitive adhesive composition to at least one surface of an optical film. In this specification, in the optical film with the pressure-sensitive adhesive in a state where the pressure-sensitive adhesive sheet is bonded to the optical film, or in the optical laminate in which the pressure-sensitive adhesive sheet is further laminated on the glass substrate, It may be simply called “adhesive layer”. The optical film used for the optical film with an adhesive is a film having optical properties, and examples thereof include a polarizing plate and a retardation film.

  A polarizing plate is an optical film having a function of emitting polarized light with respect to incident light such as natural light. The polarizing plate absorbs linearly polarized light having a vibrating surface in a certain direction and reflects linearly polarized light having a vibrating surface in a certain direction, and reflects linearly polarized light having a vibrating surface in a certain direction. There are a polarizing separation plate having a property of transmitting linearly polarized light having a vibration plane orthogonal to the polarizing plate, an elliptically polarizing plate in which a polarizing plate and a retardation film described later are laminated. As a suitable specific example of a polarizing film that expresses the function of a polarizing plate, particularly a linear polarizing plate (sometimes referred to as a polarizer), two colors such as iodine and a dichroic dye are applied to a uniaxially stretched polyvinyl alcohol resin film. The thing which the adsorptive orientation of the property pigment is mentioned.

  The retardation film is an optical film exhibiting optical anisotropy, for example, polyvinyl alcohol, polycarbonate, polyester, polyarylate, polyimide, polyolefin, cyclic polyolefin, polystyrene, polysulfone, polypropylene, polyethersulfone, polyvinylidene. Stretched film obtained by stretching a polymer film made of fluoride / polymethylmethacrylate, liquid crystal polyester, acetylcellulose, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride, etc. by about 1.0 to 6 times Is mentioned. Among them, a polymer film obtained by uniaxially or biaxially stretching a polycarbonate film or a cyclic polyolefin film is preferable. Although there exist what is called a uniaxial phase difference film, a wide viewing angle phase difference film, a low photoelasticity phase difference film, etc., it is applicable to all.

  Moreover, the film which expressed optical anisotropy by application | coating and orientation of a liquid crystalline compound, and the film which expressed optical anisotropy by application | coating of an inorganic layered compound can also be used as retardation film. In such a retardation film, a so-called temperature-compensated retardation film and a rod-like liquid crystal sold under the trade name “NH film” from JX Nippon Mining & Energy Co., Ltd. are tilted. Film, a film with a disc-shaped liquid crystal marketed under the trade name “WV film” from FUJIFILM Corporation, and a complete biaxial film sold under the trade name “VAC film” from Sumitomo Chemical Co., Ltd. There are also oriented films, such as biaxially oriented films sold under the trade name “new VAC film” by Sumitomo Chemical Co., Ltd.

  Further, those obtained by attaching a protective film to these optical films can also be used as the optical film. As the protective film, a transparent resin film is used, and as the transparent resin, for example, an acetyl cellulose resin typified by triacetyl cellulose or diacetyl cellulose, a methacrylic resin typified by polymethyl methacrylate, a polyester resin, or a polyolefin Resin, polycarbonate resin, polyether ether ketone resin, polysulfone resin and the like. The resin constituting the protective film may contain an ultraviolet absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound, and a nickel complex salt compound. As the protective film, an acetyl cellulose resin film such as a triacetyl cellulose film is preferably used.

  The linear polarizing plate mentioned above etc. are mentioned as an example of what the protective film was affixed on the optical film. The linearly polarizing plate is often used in a state where a protective film is attached to one side or both sides of a polarizing film constituting the polarizing plate, for example, a polarizing film made of polyvinyl alcohol resin. Moreover, although the above-mentioned elliptically polarizing plate is obtained by laminating a retardation film on a linearly polarizing plate, this linearly polarizing plate is often in a state where a protective film is attached to one side or both sides of the polarizing film. . When bonding the adhesive sheet of this invention to such an elliptically polarizing plate, it is normally bonded to the retardation film side.

  Moreover, it is preferable that the optical film with an adhesive of this invention sticks the peeling film to which the release process as mentioned above was given to the surface of the adhesive layer, and is temporarily attached and protected until it is used. An optical film with an adhesive provided with a release film in this way is formed, for example, by applying the above-mentioned adhesive composition to the release treatment surface of the release film to form an adhesive sheet, A method of laminating on an optical film, a method of applying a pressure-sensitive adhesive composition on an optical film to form a pressure-sensitive adhesive sheet, attaching a release film to the surface of the pressure-sensitive adhesive to protect it, and making an optical film with a pressure-sensitive adhesive Can be manufactured.

  The thickness of the pressure-sensitive adhesive layer formed on the optical film is not particularly limited, but is usually preferably 30 μm or less, more preferably 10 μm or more, and further preferably 15 to 25 μm. When the thickness of the pressure-sensitive adhesive layer is 30 μm or less, the adhesiveness under high temperature and high humidity is improved, and the possibility of occurrence of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be reduced. Moreover, it is preferable because reworkability tends to be improved. Further, if the thickness of the optical film bonded to the thickness is 10 μm or more, the pressure-sensitive adhesive layer fluctuates following the dimensional change, so that the brightness of the peripheral edge of the liquid crystal cell This is preferable because there is no difference between the brightness of the central portion and white spots and color unevenness tend to be suppressed.

[Optical laminate]
The optical film with the pressure-sensitive adhesive of the present invention can be made into an optical laminate by laminating the pressure-sensitive adhesive layer side on a glass substrate. In order to laminate an optical film with an adhesive on a glass substrate to form an optical laminate, for example, the release film is peeled off from the optical film with an adhesive obtained as described above, and the exposed adhesive layer surface is the surface of the glass substrate. You just have to stick together. As a glass substrate, the glass substrate of a liquid crystal cell, the glass for glare-proof, the glass for sunglasses etc. can be mentioned, for example. Among them, an optical film with an adhesive (upper polarizing plate) is laminated on the glass substrate on the front side (viewing side) of the liquid crystal cell, and another optical film with adhesive (lower polarizing plate) on the glass substrate on the back side of the liquid crystal cell. ) Is preferable because it can be used as a panel (liquid crystal panel) for a liquid crystal display device. Examples of the material of the glass substrate include soda lime glass, low alkali glass, non-alkali glass, and the like, and non-alkali glass is suitably used for the liquid crystal cell.

  Examples of some suitable layer configurations of the optical laminate according to the present invention are shown in cross-sectional schematic views in FIG. In the example shown in FIG. 1 (A), a polarizing film 5 is configured by sticking a protective film 3 having a surface treatment layer 2 on one surface of a polarizing film 1 on the surface opposite to the surface treatment layer 2. ing. In this example, the polarizing plate 5 is also the optical film 10 referred to in the present invention. An adhesive layer 20 is provided on the surface of the polarizing film 1 opposite to the protective film 3 to form an optical film 25 with an adhesive. And the surface on the opposite side to the polarizing plate 5 of the adhesive layer 20 is bonded to the liquid crystal cell 30 which is a glass substrate, and the optical laminated body 40 is comprised.

  In the example shown in FIG. 1B, the first protective film 3 having the surface treatment layer 2 is attached to one surface of the polarizing film 1 on the surface opposite to the surface treatment layer 2. On the other surface, a second protective film 4 is stuck to form a polarizing plate 5. Also in this example, the polarizing plate 5 is simultaneously the optical film 10 referred to in the present invention. An adhesive layer 20 is provided on the outer side of the second protective film 4 constituting the polarizing plate 5 to form an optical film 25 with an adhesive. And the surface on the opposite side to the polarizing plate 5 of the adhesive layer 20 is bonded to the liquid crystal cell 30 which is a glass substrate, and the optical laminated body 40 is comprised.

  In the example shown in FIG. 1 (C), a polarizing film 5 is formed by sticking a protective film 3 having a surface treatment layer 2 on one side of a polarizing film 1 on the surface opposite to the surface treatment layer 2. Yes. On the surface of the polarizing film 1 opposite to the protective film 3, a retardation film 7 is stuck via an interlayer adhesive 8 to constitute an optical film 10. An adhesive layer 20 is provided on the outer side of the retardation film 7 constituting the optical film 10 to constitute an optical film 25 with an adhesive. And the surface on the opposite side to the optical film 10 of the adhesive layer 20 is bonded to the liquid crystal cell 30 which is a glass substrate, and the optical laminated body 40 is comprised.

  In the example shown in FIG. 1 (D), the first protective film 3 having the surface treatment layer 2 is attached to one surface of the polarizing film 1 on the surface opposite to the surface treatment layer 2, and the polarizing film A polarizing plate 5 is configured by sticking a second protective film 4 to the other surface of 1. On the outer side of the second protective film 4 constituting the polarizing plate 5, a retardation film 7 is stuck via an interlayer adhesive 8 to constitute an optical film 10. An adhesive layer 20 is provided on the outer side of the retardation film 7 constituting the optical film 10 to constitute an optical film 25 with an adhesive. And the surface on the opposite side to the optical film 10 of the adhesive layer 20 is bonded to the liquid crystal cell 30 which is a glass substrate, and the optical laminated body 40 is comprised.

  In these examples, the first protective film 3 and the second protective film 4 are generally composed of a triacetyl cellulose film, but may be composed of the various transparent resin films described above. it can. The surface treatment layer formed on the surface of the first protective film 3 can be a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or the like. Of these, a plurality of layers may be provided.

  As shown in FIGS. 1C and 1D, when the retardation film 7 is laminated on the polarizing plate 5, a suitable example of the retardation film 7 is a medium-to-small liquid crystal display device. And a quarter-wave plate. In this case, it is general that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 which is a quarter wavelength plate are arranged so as to intersect at about 45 degrees. Depending on the characteristics, the angle may be shifted from 45 degrees to some extent. On the other hand, in the case of a large liquid crystal display device such as a television, a retardation film having various retardation values according to the characteristics of the liquid crystal cell 30 is used for the purpose of phase difference compensation and viewing angle compensation of the liquid crystal cell 30. . In this case, the polarizing plate 5 and the retardation film 7 are generally arranged so that the absorption axis and the slow axis of the retardation film 7 are substantially orthogonal or substantially parallel. When the retardation film 7 is composed of a quarter wavelength plate, a uniaxial or biaxial stretched film is preferably used. When the retardation film 7 is provided for the purpose of retardation compensation or viewing angle compensation of the liquid crystal cell 30, in addition to the uniaxial or biaxially stretched film, it is also oriented in the thickness direction in addition to the uniaxial or biaxially stretched film. What is called an optical compensation film, such as a film or a film obtained by coating and fixing a retardation-expressing substance such as liquid crystal on a support film, can also be used as the retardation film 7.

  Similarly, when the polarizing plate 5 and the retardation film 7 are bonded via the interlayer adhesive 8 as in the example shown in FIGS. 1C and 1D, the interlayer adhesive 8 includes A typical acrylic pressure-sensitive adhesive is usually used, but it is of course possible to use a pressure-sensitive adhesive sheet as defined herein. In the case where the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 are arranged so as to be substantially orthogonal or substantially parallel like the large liquid crystal display device described above, In applications where the phase difference film 7 can be roll-to-roll-bonded and re-peelability between the two is not required, the interlayer adhesive 8 shown in (C) and (D) of FIG. It is also possible to use an adhesive that can be firmly bonded once bonded and cannot be peeled off. Examples of such an adhesive include an aqueous adhesive that is composed of an aqueous solution or an aqueous dispersion, and develops an adhesive force by evaporating water as a solvent, an ultraviolet curing that cures by ultraviolet irradiation and develops an adhesive force. Examples thereof include a mold adhesive.

  1 (C) and (D) shown in FIG. 1 can also be distributed by themselves, in which the pressure-sensitive adhesive layer 20 is formed on the retardation film 7. Can be a film. An optical film with an adhesive with an adhesive layer formed on a retardation film can be bonded to a liquid crystal cell that is a glass substrate to form an optical laminate, and a polarizing plate is provided on the retardation film side. It can also paste and can be set as another optical film with an adhesive.

  FIG. 1 shows an example in which the optical film 25 with an adhesive is arranged on the viewing side of the liquid crystal cell 30, but the optical film with an adhesive according to the present invention is the back side of the liquid crystal cell, that is, the back. It can also be placed on the light side. When the optical film with pressure-sensitive adhesive of the present invention is disposed on the back side of the liquid crystal cell, a protective film having no surface treatment layer is employed instead of the protective film 3 having the surface treatment layer 2 shown in FIG. Others can be configured similarly to (A) to (D) of FIG. In this case, various optical films known to be disposed on the back side of the liquid crystal cell, such as a brightness enhancement film, a light collecting film, and a diffusion film, may be provided outside the protective film constituting the polarizing plate. Is possible.

  The optical layered body of the present invention described above can be suitably used for organic EL display devices and liquid crystal display devices. The liquid crystal display device formed from this optical laminate includes, for example, a notebook type, a desktop type, a personal computer liquid crystal display including a PDA (Personal Digital Assistant), a television, an in-vehicle display, an electronic dictionary, a digital camera, a digital It can be used for video cameras, electronic desk calculators, watches, etc.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, parts and% indicating the amount used or content are based on weight unless otherwise specified. In the following examples, the weight average molecular weight is 4 columns of “TSKgel XL” manufactured by Tosoh Corporation as a column in the GPC apparatus, and “Shodex GPC manufactured by Showa Denko KK and sold by Shoko Tsusho Corporation.” One KF-802 ”, 5 in total, are arranged in series, tetrahydrofuran is used as the eluent, sample concentration is 5 mg / mL, sample introduction amount is 100 μL, temperature is 40 ° C., flow rate is 1 mL / min, It is the value measured by standard polystyrene conversion.

  First, the example of superposition | polymerization which manufactured the acrylic resin used as the main component of an adhesive composition is shown.

[Polymerization Example 1]
In a reactor equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 169.8 parts of ethyl acetate, 98.9 parts of butyl acrylate as monomer (A-1), and monomer (A-2) ) Was charged with 1.1 parts of a mixed solution, the air in the apparatus was replaced with nitrogen gas, and the internal temperature was raised to 55 ° C. without oxygen, and then azobisisobutyroyl as a polymerization initiator. A total solution of 0.14 parts of nitrile dissolved in 5 parts of ethyl acetate was added. Thereafter, the temperature was maintained for 12 hours while maintaining the internal temperature at 54 to 56 ° C., and finally ethyl acetate was added to adjust the concentration of the acrylic resin to 20%, thereby preparing an ethyl acetate solution of the acrylic resin. The obtained acrylic resin had a polystyrene equivalent weight average molecular weight Mw by GPC of 1.78 million and Mw / Mn of 4.86. This is designated as acrylic resin A.

[Polymerization Example 2]
An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 1 except that the amount of butyl acrylate charged was 97.0 parts and the amount of acrylic acid charged was 3.0 parts. The obtained acrylic resin had a polystyrene equivalent weight average molecular weight Mw by GPC of 1,540,000 and Mw / Mn of 4.69. This is designated as acrylic resin B.

  Table 1 summarizes the charge composition of the monomers in the above Polymerization Examples 1 and 2 and the weight average molecular weight and Mw / Mn of the resulting acrylic resin. In Table 1, “BA” in the column of “monomer charge composition (part)” means butyl acrylate, and AA means acrylic acid.

  Next, examples and comparative examples in which pressure-sensitive adhesives were prepared using the acrylic resin produced above and applied to optical films are shown. In the following examples, the following were used as the crosslinking agent, the carboxyl group-containing (meth) acrylic acid ester monomer, and the silane compound, respectively. The first name is the product name.

<Crosslinking agent>
Takenate D-110N: Ethyl acetate solution (solid content concentration 75%) of trimethylolpropane adduct of xylylene diisocyanate, obtained from Mitsui Chemicals, Inc. In Table 2 below, it is abbreviated as “D110N”.
Coronate L: Trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate solution (solid content: 75%), obtained from Nippon Polyurethane Co., Ltd. In Table 2 below, it is abbreviated as “Cor-L”.
Takenate D-204EA: Ethylene acetate solution of isocyanurate form of tolylene diisocyanate (solid content: 50%), obtained from Mitsui Chemicals, Inc. In Table 2 below, it is abbreviated as “D204EA”.

<Carboxyl group-containing (meth) acrylic acid ester monomer>
β-CEA: 2-carboxyethyl acrylate sold by Daicel Cytec Co., Ltd. under the trade name “β-CEA”. Its chemical composition is
CH ₂ = CH (COOCH ₂ CH ₂ ) _n COOH (n = average 1)
Specifically, 2-carboxyethyl acrylate (that is, acrylic acid dimer) 40%, acrylic acid trimer or higher oligomer 40%, and acrylic acid 20%. Hereinafter, “β-CEA” is displayed following the product name. In the following description, “2-carboxyethyl acrylate” refers to a dimer of acrylic acid, that is, CH ₂ ═CHCOOCH ₂ CH ₂ COOH.
It shall refer to itself.

<Silane compound>
KBM-403: 3-glycidoxypropyltrimethoxysilane, liquid, obtained from Shin-Etsu Chemical Co., Ltd.

[Examples 1-3 and Comparative Examples 1-3]
(A-1) Production of pressure-sensitive adhesive compositions 1 to 3 Using the 20% ethyl acetate solution of acrylic resin A and the 20% ethyl acetate solution of acrylic resin B prepared in Polymerization Examples 1 and 2, each acrylic resin (solid Min) With respect to 100 parts, the respective amounts of the above-mentioned crosslinking agents shown in Table 2, 0.1 part of carboxyl group-containing acrylate monomer (β-CEA), and silane compound (KBM-403) 0.5 parts of the mixture was mixed, and ethyl acetate was further added so that the solid content concentration was 13% to prepare an adhesive composition. In addition, although the used crosslinking agent is an ethyl acetate solution as above-mentioned, the addition amount shown in Table 2 is the solid content.

(A-2) Manufacture of adhesive composition 4-6 Adhesive agent which does not mix | blend a carboxyl group-containing acrylate ester monomer ((beta) -CEA), but performs operation according to the above (a-1) others. Compositions 4-6 were prepared.

(B) Preparation of pressure-sensitive adhesive sheet Each of the pressure-sensitive adhesive compositions prepared in the above (a-1) and (A-2) was subjected to a release treatment to a polyethylene terephthalate film [trade name “SP-PLR382050”, (Applied from Lintec Co., Ltd., referred to as separator)] was applied to the release-treated surface using an applicator so that the thickness after drying was 20 μm, and then dried at 100 ° C. for 1 minute. Produced.

(C) Gel fraction measurement of pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet prepared in (b) above was left at room temperature for 1 day, then left for 4 days, and after 7 days, respectively. The gel fraction was measured by the method. The value after leaving for 1 day is in the column “1st day” in Table 2, the value after being left for 4 days in the “4th day” column in Table 2, and the value after being left for 7 days in “2” in Table 2. These are shown in the “day” column.

(D) Preparation of polarizing plate with pressure-sensitive adhesive The polarizing plate having a three-layer structure in which both surfaces of a polarizing film in which iodine is adsorbed and oriented on polyvinyl alcohol is sandwiched between protective films made of triacetyl cellulose are combined with the above (b ), The surface of the pressure-sensitive adhesive sheet opposite to the separator (pressure-sensitive adhesive surface) was pasted with a laminator, and then cured for 7 days at a temperature of 23 ° C. and a relative humidity of 65%. Produced.

(E) Production of optical laminate After separating the separator from the pressure-sensitive adhesive polarizing plate produced in (d) above, the pressure-sensitive adhesive surface was a glass substrate for liquid crystal cells [trade name “EAGLE XG”, obtained from Corning] An optical laminate was prepared by sticking to both sides so as to be crossed Nicol. When this optical laminated body was subjected to a heat resistance test for 300 hours under dry conditions at a temperature of 80 ° C. (indicated as “heat resistance” in Table 2), a moisture heat resistance test for 300 hours at a temperature of 60 ° C. and a relative humidity of 90%. (In Table 2, it is expressed as “moisture heat resistance”), and the process of lowering the temperature from −70 ° C. to 70 ° C. and then raising the temperature to 70 ° C. is defined as one cycle (1 hour). When the heat shock resistance test was repeated for 100 cycles (indicated as “HS resistance” in Table 2), the optical laminate after the test was visually observed. The results were classified according to the following criteria and summarized in the “Durability” column of Table 2.

<Evaluation criteria for heat resistance test, moist heat resistance test and heat shock resistance test>
A: No change in appearance such as floating, peeling or foaming is observed.
○: Almost no change in appearance such as floating, peeling or foaming.
Δ: Appearance changes such as floating, peeling and foaming are slightly noticeable.
X: Remarkable changes in appearance such as floating, peeling, foaming, etc.

(F) Reworkability evaluation of optical film with adhesive Reworkability was evaluated by the following method. First, the polarizing plate with an adhesive produced in the above (d) was cut into a test piece having a size of 25 mm × 150 mm. Next, the separator is peeled off from the test piece, and the pressure-sensitive adhesive surface is attached to a glass substrate for a liquid crystal cell using a sticking apparatus (trade name “Lamipacker” manufactured by Fuji Plastics Co., Ltd.), temperature 50 ° C., pressure 5 kg / pressure. Autoclaving was performed at cm ² (490.3 kPa) for 20 minutes. Next, after heat-treating at 70 ° C. for 2 hours and subsequently storing in an oven at 50 ° C. for 48 hours, the polarizing plate is removed from the adhesion test piece in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%. It peeled in the direction of 180 ° with the layer at a speed of 300 mm / min (direction parallel to the glass surface when the polarizing plate was peeled upside down), observed the state of the glass plate surface, and classified according to the following criteria: . The results are also shown in the “Rework” column of Table 2.

<Evaluation criteria for reworkability>
A: No fogging or the like is observed on the glass substrate surface.
A: Almost no fogging or the like is observed on the glass substrate surface.
(Triangle | delta): Cloudiness etc. are recognized by the glass substrate surface.
X: The remainder of an adhesive is recognized by the glass substrate surface.

  As shown in Table 1 and Table 2, an acrylic resin having a carboxyl group is blended with an isocyanate crosslinking agent having an aromatic ring and 2-carboxyethyl acrylate corresponding to the formula (II) to prepare an adhesive composition. Example 1-3 which comprised and formed the adhesive sheet from this is a sheet form compared with Comparative Examples 1-3 which formed the adhesive sheet from the adhesive composition in which 2-carboxyethyl acrylate was not mix | blended. The gel fractions on the 1st, 4th and 7th days after coating are high.

  Specifically, in Example 1 and Comparative Example 1, xylylene diisocyanate is used as a crosslinking agent, but Comparative Example 1 in which a pressure-sensitive adhesive sheet is formed from a composition not containing 2-carboxyethyl acrylate has a sheet shape. In Example 1 where the pressure-sensitive adhesive sheet was formed from a composition containing 2-carboxyethyl acrylate, the gel fraction was less than 10% even on the seventh day after coating. The gel fraction in the 20% range is given even on the first day after the construction, and the gel fraction has reached the 40% range on the 4th and 7th days, and the speed of the crosslinking reaction has been greatly accelerated. I understand. In Examples 2 and 3 and Comparative Examples 2 and 3, tolylene diisocyanate was used as a cross-linking agent, and Comparative Examples 2 and 3 in which a pressure-sensitive adhesive sheet was formed from a composition not containing 2-carboxyethyl acrylate were also sheet-like. In Examples 2 and 3, in which a pressure-sensitive adhesive sheet was formed from a composition containing 2-carboxyethyl acrylate, the corresponding gel fraction was given on the 7th day after coating. It can be seen that is further enhanced.

  Therefore, by using a pressure-sensitive adhesive composition in which 2-carboxyethyl acrylate corresponding to the formula (II) is blended, the coating property when applied in a sheet form is good and the coating is performed. The curing time until processing such as cutting can be performed without problems can be shortened, and an adhesive sheet excellent in processability can be obtained. In addition, the pressure-sensitive adhesive sheets of Examples 1 to 3 gave results equal to or higher than those of Comparative Examples 1 to 3 in heat resistance, moisture and heat resistance, and heat shock resistance when applied to the polarizing plate.

  The pressure-sensitive adhesive sheet of the present invention can shorten the curing time required until processing can be performed after forming the sheet, and is excellent in workability and durability. The optical film provided with the pressure-sensitive adhesive sheet is suitably used for a liquid crystal display device.

1 …… Polarizing film,
2 ... Surface treatment layer
3 ... (first) protective film,
4 …… Second protective film,
5 ... Polarizing plate,
7 ... retardation film,
8 …… Interlayer adhesive,
10 …… Optical film,
20 ... Adhesive layer (adhesive sheet) bonded to the liquid crystal cell (glass substrate),
25 …… Optical film with adhesive,
30 ... Liquid crystal cell (glass substrate),
40: Optical laminate.

Claims (6)

(A) (A-1) The following formula (I)

(Wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 14 or less carbon atoms) (meth) acrylic acid ester 75 to 99.9% by weight, and (A-2 ) 0.1-5% by weight of (meth) acrylic monomer having a carboxyl group
An acrylic resin which is a copolymer obtained from a monomer mixture containing
(B) a crosslinking agent comprising an isocyanate compound having an aromatic ring and at least two isocyanato groups in the molecule, and (C) the following formula (II)

(In the formula, R ₃ represents a hydrogen atom or a methyl group, and A represents a divalent organic group having 2 to 4 carbon atoms) and a pressure-sensitive adhesive containing a carboxyl group-containing (meth) acrylic acid ester monomer A pressure-sensitive adhesive sheet which is formed into a sheet form from the adhesive composition.   The pressure-sensitive adhesive sheet according to claim 1, further comprising (D) a silane compound.   The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein a release film is adhered to at least one surface.   An optical film with an adhesive, wherein the adhesive sheet according to claim 1 or 2 is bonded to an optical film.   The optical film with an adhesive according to claim 4, wherein the optical film is selected from a polarizing film and a retardation film.   An optical laminated body, wherein the optical film with an adhesive according to claim 4 or 5 is laminated on a glass substrate on the adhesive sheet side.

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