JP2013189601A - Adhesive and adhesive film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive capable of forming an adhesive layer which, when used on an adhesive film, presents high detachability, hardly causes a float or peeling from an adherend even after being exposed to a high temperature environment or a high-humidity/temperature environment, presents an excellent result of a light leakage evaluation, and also generates no indentation in production of the adhesive film.SOLUTION: An adhesive includes an acrylic copolymer (A) and an isocyanate compound (B), the copolymer (A) being copolymerized with a monomer containing hydroxyl group (1) and including a high-molecular-weight component (H) and a low-molecular-weight component (L) (2), wherein the high-molecular-weight component (H1) has a peak with 700,000-2,200,000 weight-average molecular weight, the low-molecular-weight component (L1) has a peak with 10,000-150,000 weight-average molecular weight, and an area ratio between the peak of the high-molecular-weight component (H1) and the peak of the low-molecular-weight component (L1) is (H1)/(L1)=65/35 to 35/65.

Description

  The present invention relates to a pressure-sensitive adhesive suitable for production of a display such as a liquid crystal.

Display devices such as liquid crystal displays are used in various devices such as home appliances and commercial appliances such as electronic computers, electronic watches, mobile phones, and televisions. Especially, liquid crystal and plasma televisions are becoming larger. In recent years, it has also been used for in-vehicle devices such as car navigation, and is required to withstand severe conditions such as high temperature and high humidity.
In the display device, polarizing plates and retardation plates having various optical functions are used, and these are attached to an adherend such as glass through an adhesive.

  The polarizing plate is a laminate having a configuration in which a polyvinyl alcohol film is sandwiched between triacetyl cellulose-based films and cycloolefin-based films. And since each said film has a different mechanical characteristic, the dimensional change rate at the time of a heating also differs, Therefore When it puts in a high temperature atmosphere, a curvature will arise in a laminated body in many cases.

  Therefore, for example, when a laminate composed of a polarizing plate / adhesive layer / glass (of a liquid crystal cell) is placed under high temperature or high temperature and high humidity conditions, and the warpage resulting from dimensional changes occurs in the polarizing plate, the adhesive layer There is a problem that bubbles (foaming) are generated at the bonding interface between the glass and the glass, or the polarizing plate is lifted from the glass and peeled off. Also, the stress distribution of the laminate becomes uneven due to warpage, and as a result of stress concentration at the four corners of the laminate or at the peripheral edges, light leaks from the four corners and peripheral edges of the laminate, so-called The problem of “light leakage phenomenon” occurred.

  In addition, when a polarizing plate is bonded to an optical component such as a liquid crystal cell in the manufacturing process of a liquid crystal display or the like, the polarizing plate is peeled off after a certain time has elapsed since the bonding position has shifted. It may be necessary to reuse expensive liquid crystal cells. Therefore, there is a need for a pressure-sensitive adhesive having re-peeling performance that can be peeled relatively easily from a liquid crystal cell even after a certain period of time after being bonded via a pressure-sensitive adhesive applied to a polarizing plate. It has been.

  Various pressure-sensitive adhesives have been proposed as pressure-sensitive adhesives that satisfy such requirements. For example, in order to solve the problem of light leakage, a technique for imparting stress relaxation properties by appropriately softening the adhesive layer by adding a plasticizer or the like to the adhesive is disclosed (see Patent Document 1). .

  In order to impart stress relaxation properties, the value (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) of the acrylic copolymer by the number average molecular weight (Mn) is adjusted to 10 to 50, and the molecular weight distribution is adjusted. A technique for increasing the stress relaxation property of the coating film and preventing light leakage is disclosed (see Patent Document 2).

  Furthermore, by reducing the content of the monomer having a hydroxyl group in the acrylic copolymer to 0.01 to 0.5 parts by weight as much as possible, the stress relaxation property of the coating film is improved and light leakage is reduced. Has been disclosed (see Patent Document 3).

  On the other hand, in order to impart removability, a low molecular weight acrylic polymer having a high acid value and a weight average molecular weight of 0.2 to 100,000 is used for a high molecular weight acrylic polymer having a weight average molecular weight of 500,000 or more. A technique for blending is disclosed (see Patent Document 4).

Japanese Patent Laid-Open No. 9-87593 JP 2007-169329 A JP 2010-276560 A JP 2010-1000071 A

  However, in the pressure sensitive adhesive of Patent Document 1, the addition of a plasticizer causes blisters that contaminate the adherend when the polarizing plate is peeled off and reduces cohesive force. It becomes easy.

  Moreover, in the adhesive of patent document 2, it is hard to say that white spots occur in the light leakage evaluation and the optical characteristics are excellent.

  In addition, the pressure-sensitive adhesive of Patent Document 3 can suppress the light leakage phenomenon, but since the crosslink density is low, it is imprinted by foreign matters when producing a pressure-sensitive adhesive film (hereinafter also referred to as “indentation”). ) Are likely to occur, and the yield is poor.

  Moreover, in the adhesive of patent document 4, the acid value of a low molecular weight body is high, and the isocyanate compound currently used as a hardening | curing agent reacts preferentially with the water | moisture content which exists in the vicinity of a low molecular weight body, and deactivates. Therefore, a sufficient crosslinked structure cannot be formed. Therefore, it is necessary to use an organic peroxide crosslinking agent in combination. However, since the organic peroxide is decomposed by heat during drying to generate radicals to form a crosslinking agent, the drying conditions are limited.

  The present invention, when used for an adhesive film, has excellent releasability, and is less likely to float or peel off from the adherend even after being exposed to a high temperature environment or a high temperature and high humidity environment. It aims at providing the adhesive which can create not only the impression layer at the time of adhesive film production but also the adhesive layer which can be produced.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the pressure-sensitive adhesive shown below, and have completed the present invention.

That is, the present invention is a pressure-sensitive adhesive containing an acrylic copolymer (A) and an isocyanate compound (B), wherein the copolymer (A)
(1) Copolymerized 0.5 to 2.0% by weight of a monomer (a) containing a hydroxyl group and another monomer (b) copolymerizable with (a). Yes (provided that the total of (a) and (b) is 100% by weight),
(2) including a high molecular weight component (H) and a low molecular weight component (L);
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 Low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak and the low molecular weight component (L1) peak is
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a weight average molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
The present invention relates to an adhesive.

  The present invention also relates to the above pressure-sensitive adhesive, comprising 0.05 to 5 parts by weight of an isocyanate compound (B) with respect to 100 parts by weight of the acrylic copolymer (A).

  Moreover, this invention relates to the said adhesive in which an isocyanate type compound (B) contains the compound (B-1) which has two isocyanate groups in a molecule | numerator.

  Moreover, this invention relates to the said adhesive which contains tackifying resin further.

In the present invention, the acrylic copolymer (A) contains 0.5 to 2.0% by weight of the monomer (a) containing a hydroxyl group, and other monomers that can be copolymerized with the (a). The body (b) is radically copolymerized until the polymerization conversion becomes 30 to 70% to synthesize a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000,
Subsequently, it is related with the said adhesive which is obtained by adding a polymerization initiator and radical-copolymerizing said (a) and (b) until the polymerization conversion rate will be 80 to 100%.

In the present invention, the acrylic copolymer (A) contains 0.5 to 2.0% by weight of the monomer (a) containing a hydroxyl group, and other monomers that can be copolymerized with the (a). The body (b) is radically copolymerized until the polymerization conversion becomes 30 to 70% to synthesize a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000,
Next, the monomer (b) is further added, and the above pressure-sensitive adhesive is obtained by further radical copolymerization of the above (a) and (b) until the polymerization conversion rate becomes 80 to 100%.

Moreover, this invention relates to the manufacturing method of an adhesive containing the following (I)-(III):
(I) A monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the above (a) have a polymerization conversion rate of 30 to 30%. Radical copolymerization to 70% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000 (provided that the total of (a) and (b) is 100% by weight) Do);
(II) Next, a polymerization initiator is added, and the above (a) and (b) are further radically copolymerized until the polymerization conversion becomes 80 to 100%,
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 The low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak to the low molecular weight component (L1) peak is:
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a weight average molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
Obtaining an acrylic copolymer (A) comprising a high molecular weight component (H) and a low molecular weight component (L); and (III) the acrylic copolymer (A) and an isocyanate compound (B). Mixing.

Moreover, this invention relates to the manufacturing method of an adhesive containing the following (I)-(III):
(I) A monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the above (a) have a polymerization conversion rate of 30 to 30%. Radical copolymerization to 70% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000;
(II) Then, the monomer (b) is further added, and the above (a) and (b) are further radically copolymerized until the polymerization conversion becomes 80 to 100% (provided that (a) and (b) Of 100% by weight),
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 The low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak to the low molecular weight component (L1) peak is:
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a weight average molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
Obtaining an acrylic copolymer (A) comprising a high molecular weight component (H) and a low molecular weight component (L); and (III) the acrylic copolymer (A) and an isocyanate compound (B). Mixing.

  Moreover, this invention relates to the adhesive obtained by the said manufacturing method.

  Moreover, this invention relates to the adhesive film characterized by having a base material and the adhesion layer formed from the said adhesive.

  The present invention also relates to the above adhesive film, wherein the substrate is an optical member.

  Moreover, this invention relates to the said adhesive film whose optical member is a polarizing plate.

  According to the present invention configured as described above, the pressure-sensitive adhesive layer is excellent in stress relaxation properties not only after high-temperature treatment but also after high-temperature and high-humidity treatment. Therefore, even when a polarizing plate that causes dimensional changes in a high-temperature and high-humidity environment is used as a base material, the possibility that the adhesive layer may float or peel over a long period of time can be reduced. In addition, when a polarizing film using this adhesive layer is used in a liquid crystal display device, the stress concentration caused by the contraction of the polarizing plate is alleviated, so that the light leakage phenomenon can be suppressed. As a result, even after exposure to high-temperature and high-temperature and high-humidity environments, it is difficult to lift and peel off the adherend. I was able to create a layer.

  The optical pressure-sensitive adhesive of the present invention contains an acrylic copolymer (A) and an isocyanate compound (B). The acrylic copolymer (A) comprises 0.5% to 2.0% by weight of a monomer (a) containing a hydroxyl group and another monomer (b) copolymerizable with the above (a). The adhesive layer is formed by a cross-linking reaction between a hydroxyl group in the acrylic copolymer (A) and an isocyanate group in the isocyanate compound (B).

  The three-dimensional network structure by the crosslinking reaction of the hydroxyl group in the acrylic copolymer (A) and the isocyanate group in the isocyanate compound (B) gives the cohesive force to the adhesive layer, and is a harsh environment such as high temperature and high temperature and high humidity. Even underneath, it is possible to suppress foaming, floating and peeling of the adhesive layer.

  In the present invention, the acrylic copolymer (A) is a monomer copolymer containing a (meth) acrylic acid ester. In the present invention, (meth) acrylic acid ester means at least one of acrylic acid ester and methacrylic acid ester.

  The monomer (a) containing a hydroxyl group is preferably used in an amount of 0.5 to 2.0% by weight, more preferably 0.5 to 2.0% in a total of 100% by weight of the monomers (a) and (b). 1.5% by weight is more preferred. When the amount used is less than 0.5% by weight, the acrylic copolymer (A) has few crosslinking points and has a low crosslinking density, which may cause imprints due to foreign matters during the production of the adhesive film. If the amount used exceeds 2.0% by weight, the crosslink density becomes too high, so that the stress concentration caused by the contraction of the polarizing plate cannot be relaxed, and there is a possibility that a light leakage phenomenon may occur. In the present invention, it is important to control the amount of the monomer (a) containing a hydroxyl group, and it is possible to suppress indentation and light leakage by appropriately using 0.5 to 2.0% by weight. It becomes.

  Examples of the monomer (a) containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic such as 2-hydroxybutyl, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate Glycol mono (meth) acrylates such as acid hydroxyalkyl esters, polyethylene glycol mono (meth) acrylates, polypropylene glycol mono (meth) acrylates, 1,4-cyclohexanedimethanol mono (meth) acrylates , Caprolactone modified Meth) acrylic acid esters, such as hydroxyethyl acrylamide. These may be used alone or in combination of two or more. Among these, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

  Other monomers (b) are: a monomer containing a carboxyl group, a monomer containing an amide bond, a monomer containing an epoxy group, a monomer containing an amino group, (meth) acrylic Examples thereof include, but are not limited to, acid alkyl esters, alkoxy (poly) alkylene oxide (meth) acrylic acid esters, vinyl acetate, vinyl crotonic acid, styrene, acrylonitrile and the like.

  Examples of the monomer containing a carboxyl group include (meth) acrylic acid, monohydroxyethyl acrylate ester of phthalate, p-carboxybenzyl acrylate ester, ethylene oxide modified (added mole number: 2 to 18) phthalate acrylic. Acid ester, monohydroxypropyl acrylate phthalate, monohydroxyethyl acrylate succinate, β-carboxyethyl acrylate, 2- (4-benzoyl-3-hydroxyphenoxy) ethyl acrylate, maleic acid, monoethyl maleate Examples include acid, itaconic acid, citraconic acid, and fumaric acid. These may be used alone or in combination of two or more.

  Examples of the monomer containing an amide bond include (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminopropyl (meth) ) Heterocycles such as (meth) acrylamide compounds such as acrylamide, diacetone acrylamide, N- (hydroxymethyl) acrylamide, N- (butoxymethyl) acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, etc. , N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide and the like. These may be used alone or in combination of two or more.

  Examples of the monomer containing an epoxy group include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl (meth) acrylate. Examples include 3,4-epoxycyclohexylmethyl.

  Examples of the monomer containing an amino group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate. And (meth) acrylic acid monoalkylamino esters.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) Hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, (meth ) Hexadecyl acrylate, octadecyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Among these compounds, butyl (meth) acrylate is preferable among these compounds because it is easy to obtain good adhesive performance.

  Examples of the alkoxy (poly) alkylene oxide (meth) acrylic acid ester include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, methoxypolyethylene glycol (meth) acrylic acid ester, and ethoxypolyethylene. Glycol (meth) acrylic acid ester, methoxypolypropylene glycol (meth) acrylic acid ester, ethoxypolypropylene glycol (meth) acrylic acid ester, phenoxypolyethylene glycol (meth) acrylic acid ester, phenoxypolypropylene glycol (meth) acrylic acid ester, etc. It is done.

The acrylic copolymer (A) contains a high molecular weight component (H) and a low molecular weight component (L).
There are the following three types of acrylic copolymers (A) depending on the form indicated by the discharge curve of gel permeation chromatography (hereinafter also referred to as “GPC”). Note that the peak here refers to a region having an area between the discharge curve and the baseline of the discharge curve. When the peak top is included, the region other than the peak top is also included. Moreover, it may not necessarily have a peak top.
(2-1) A type in which the high molecular weight component (H1) and the low molecular weight component (L1) form a completely independent peak on GPC.
(2-2) A type showing a continuous peak in which a high molecular weight component (H2) and a low molecular weight component (L2) are connected by a minimum value (valley) on the GPC emission curve. The minimum value here means the minimum value within the continuous peak (excluding both ends of the continuous peak), with the high molecular weight component (H2) on the high molecular weight side and the low molecular weight side on the low molecular weight side. Let it be a molecular weight component (L2). In many cases, the minimum value is between about 100,000 and 500,000 molecular weight.
(2-3) A type in which the high molecular weight component (H3) and the low molecular weight component (L3) show continuous peaks on the GPC emission curve and do not have a clear minimum value. In this case, with the molecular weight of 300,000 as the boundary, the high molecular weight side is the high molecular weight component (H3) and the low molecular weight side is the low molecular weight component (L3).

  In the present invention, the weight average molecular weight is a value in terms of polystyrene measured by GPC.

  The optical pressure-sensitive adhesive of the present invention contains the high molecular weight component (H) and the low molecular weight component (L), so that the presence of the low molecular weight component (L) in addition to the cohesive force of the high molecular weight component (H). This makes it possible to form an adhesive layer having both stress relaxation properties.

  The high molecular weight component (H) and the low molecular weight component (L) contained in the acrylic copolymer (A) are classified and specified as any one of the types (2-1) to (2-3). (H1) and (L1), (H2) and (L2), or (H3) and (L3). In any specific method, the high molecular weight component (H) has a weight average molecular weight of 700,000 to 2,200,000, and the low molecular weight component (L) has a weight average molecular weight of 10,000 to 150,000. The area ratio of the molecular weight component (H) peak to the low molecular weight component (L) peak is (H) / (L) = 65/35 to 35/65.

  The weight average molecular weights of the high molecular weight components (H1), (H2), and (H3) specified as described above are 700,000 to 2,200,000, and preferably 800,000 to 2,000,000. The weight average molecular weights of the low molecular weight components (L1), (L2), and (L3) specified as described above are 10,000 to 150,000, and preferably 30,000 to 120,000. When the weight average molecular weight of the high molecular weight component (H) is less than 700,000, the cohesive force of the adhesive layer is insufficient even when reacted with the isocyanate compound (B) described later, and foaming, floating and peeling occur. On the other hand, if the weight average molecular weight of the high molecular weight component (H) is greater than 2,200,000, the viscosity becomes high and the workability such as coating becomes inferior, and the optical properties cannot be maintained. On the other hand, when a low molecular weight component (L) having a weight average molecular weight of less than 10,000 is used, the cohesive force is insufficient, and foaming, floating and peeling are likely to occur. If a low molecular weight component (L) having a weight average molecular weight exceeding 150,000 is used, stress concentration caused by contraction of the polarizing plate cannot be relaxed, and a light leakage phenomenon occurs.

  Furthermore, the area ratio of the peak in GPC of the high molecular weight components (H1), (H2), (H3) and the low molecular weight components (L1), (L2), (L3) is (H1) / (L1) = 65 / 35 to 35/65, or (H2) / (L2) = 65/35 to 35/65, or (H3) / (L3) = 65/35 to 35/65. It is important that 60/40 to 40/60 respectively. If the proportion of the low molecular weight component (L) is too small, the stress concentration caused by the contraction of the polarizing plate cannot be relaxed, and a light leakage phenomenon occurs. On the other hand, when the proportion of the low molecular weight component (L) is too large, the cohesive force of the adhesive layer is insufficient, and foaming, floating and peeling are likely to occur. Furthermore, a high-molecular-weight component (H) and a low-molecular-weight component (L) are contained at a ratio of 65/35 to 35/65, so that the adhesive layer has good reworkability even after being subjected to harsh conditions. Can be obtained.

Such an acrylic copolymer (A) can be obtained by various methods. For example, the high molecular weight component (H) and the low molecular weight component (L) can be obtained separately and mixed together, or the high molecular weight components (that is, the above (H1) to (H3) In the presence of the obtained copolymer to obtain a low molecular weight component, and a copolymer containing both is obtained. A polymer (A) can also be obtained.
From the viewpoint of maintaining optical properties at high temperature or high temperature and high humidity, the latter method is more preferable.

  In the following, a copolymer containing a high molecular weight component, which is a more preferred method, was obtained (first stage polymerization), and then the monomer was polymerized in the presence of the obtained copolymer (second stage polymerization). ) To obtain a low molecular weight component in more detail. For example, the high molecular weight component is 0.01 to 1 part by weight of the polymerization initiator, more preferably 0.1 parts by weight based on 100 parts by weight of the monomers (a) and (b) used in the first stage. It is obtained by a method such as bulk polymerization or solution polymerization, preferably solution polymerization, using 01 to 0.1 parts by weight of a polymerization initiator.

  As the polymerization initiator, an azo compound or an organic peroxide is used, and two or more polymerization initiators may be used in combination. In the case of solution polymerization, as a polymerization solvent, methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol, etc. are used. It is done. Two or more kinds of polymerization solvents may be mixed and used.

  Among the polymerization initiators, examples of the azo compound 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- Methyl propionate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis (2- (2-imidazoline) -2-yl) propane) and the like.

  Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  First, it is preferable to polymerize the monomers (a) and (b) until the polymerization conversion becomes 30 to 70% by controlling the blending amount of the polymerization initiator as described above. First, a copolymer constituting the high molecular weight component (H) of the acrylic copolymer (A) can be obtained in the system by the stepwise polymerization. The copolymer obtained by the first stage polymerization mainly comprises the high molecular weight component (H), but may contain other copolymerization components. Here, the polymerization conversion rate is a value obtained by dividing the weight of the copolymer obtained by polymerizing the monomer by the total weight of the monomers used as raw materials. More specifically, a very small amount of the solution during polymerization is sampled and heated at 150 ° C. for about 20 minutes to obtain the solid content. The monomer volatilizes under the heating conditions, but the copolymer does not volatilize. Therefore, by obtaining the solid content of the solution, the amount of the copolymer contained can be obtained, and the polymerization conversion rate is calculated based on that.

  Then, if necessary, a new monomer (a) and / or (b) and / or a polymerization initiator is added, and as a second stage polymerization, a monomer remaining in the system after the first stage polymerization. (And a new monomer added as needed) is further radically polymerized to form the low molecular weight component (L). Thereby, the acrylic copolymer (A) containing a high molecular weight component (H) and a low molecular weight component (L) can be obtained. The polymerization conversion rate of the acrylic copolymer (A) in the second stage polymerization is preferably 80 to 100%, and more preferably 90 to 100%. That is, the monomer remaining in the reaction system is preferably 20% of the total 100% by weight of the monomers used in the polymerization, including the monomer added as necessary in the second stage polymerization step. The acrylic copolymer (A) can be obtained by radical copolymerization to form a low molecular weight component until it is less than 10%, more preferably less than 10% by weight.

  When the low molecular weight component (L) is formed in the second stage polymerization, the polymerization initiator used in the first stage is more than the polymerization initiator used in the first stage. It is preferable to use about 50 times the weight of the polymerization initiator. More specifically, 0.05 to 10 parts by weight of a polymerization initiator, more preferably 0.05 with respect to 100 parts by weight of the total of the monomers (a) and (b) used in the second stage. It is preferred to use -5 parts by weight of a polymerization initiator. Furthermore, in order to control the molecular weight to the low molecular weight side, during the synthesis of the low molecular weight component (L), mercaptans such as n-lauryl mercaptan and n-dodecyl mercaptan, chain transfer agents such as α-methylstyrene dimer and limonene are used. May be used. Thus, in GPC, the copolymer (A) in which the area ratio of the high molecular weight component (H) and the low molecular weight component (L) is (H) / (L) = 65/45 to 35/65 is preferably used. Can be obtained.

  A pressure-sensitive adhesive can be obtained by mixing the acrylic copolymer (A) having a hydroxyl group obtained as described above and an isocyanate compound (B) as a curing agent. Upon mixing, the acrylic copolymer (A) is preferably in a solution state dissolved in an organic solvent.

The isocyanate compound (B) is preferably blended in an amount of 0.05 to 5 parts by weight, more preferably 0.05 to 2 parts by weight, per 100 parts by weight of the acrylic copolymer (A). If it is less than 0.05 part by weight, the cohesive force of the adhesive layer tends to decrease, and if it exceeds 5 parts by weight, the stress relaxation property of the adhesive layer becomes poor.

  As an isocyanate type compound (B), what has two or more isocyanate groups in a molecule | numerator is preferable, and what has 2-4 pieces is more preferable, Especially, the compound (B-1 which has two isocyanate groups in a molecule | numerator). Is more preferable. By blending the isocyanate compound (B) as a curing agent, desired adhesive properties can be obtained. An isocyanate type compound (B) may be used independently and may be used in combination of 2 or more types arbitrarily. The number of isocyanate groups is an average number.

The following are mentioned as an example of an isocyanate type compound (B).
Examples of the compound having 3 or more isocyanate groups in the molecule include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, Adducts, burettes or isocyanurates of isocyanate monomers such as naphthalene diisocyanate, triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate and polyol compounds such as trimethylolpropane, and these polyether monomers and known polyether polyols or polyesters Polyol, acrylic polyol, polyb Diene polyol, an adduct or the like of the polyisoprene polyol and the like. Among these, a trimethylolpropane adduct body of tolylene diisocyanate and a trimethylolpropane adduct body of xylylene diisocyanate are preferable because they can be easily adjusted to an appropriate gel fraction.
Examples of the compound (B-1) having two isocyanate groups in the molecule include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl. Isocyanate groups in one molecule obtained by reacting a monofunctional alcohol with an isocyanate monomer such as xylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, or the above compound having three or more isocyanate groups in one molecule. , And further, allophanate of hexamethylene diisocyanate (coronate 2770: Made this Polyurethane Industry Co., Ltd.), and the like. Among these, hexamethylene diisocyanate allophanate is preferable from the viewpoint of compatibility with the acrylic copolymer (A).

  Specifically, a compound having three or more isocyanate groups in one molecule is reacted with a monofunctional alcohol to make the number of isocyanate groups in two molecules two. Specifically, a trimethylolpropane adduct of tolylene diisocyanate is used. And trimethylolpropane adducts of xylylene diisocyanate reacted with monofunctional alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, octyldodecyl alcohol, etc. The reaction conditions are nitrogen atmosphere, reaction temperature It is preferable to react at 60 to 100 ° C. for 2 to 8 hours.

  The pressure-sensitive adhesive of the present invention may be used in combination with a curing agent other than the isocyanate compound (B). For example, one or more of an epoxy compound, an ethyleneimine compound, a metal chelate compound, and an amine compound can be used in combination with the isocyanate compound (B). It is preferable that the compounding quantity in the case of mix | blending hardeners other than these isocyanate type compounds (B) is 0.01-5 weight part with respect to 100 weight part of acrylic copolymers (A).

  Examples of epoxy compounds include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diester. Glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane N, N, N ′, N′-tetraglycidylaminophenylmethane and the like.

  Examples of the ethyleneimine compound include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxite), N, N′-toluene-2,4-bis (1-aziridinecarboxite), Bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxite), 2,2′- Bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinylpropionate, Tris-2,4 , 6- (1-aziridinyl) -1,3,5-triazine and the like.

  Examples of metal chelate compounds include coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone or ethyl acetoacetate. Is mentioned.

  Furthermore, examples of the amine compound include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin, and methylene resin.

  The pressure-sensitive adhesive of the present invention preferably contains a tackifier resin. By using the tackifying resin, the adhesion between the adhesive layer and the adherend is improved, and the heat resistance and heat-and-moisture resistance may be further improved. The amount of the tackifying resin used is preferably in the range of 0.1 to 30 parts by weight, particularly preferably in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the acrylic copolymer (A).

  Examples of the tackifying resin include rosin derivative resins, polyterpene resins, aliphatic petroleum resins, aromatic petroleum resins, aliphatic / aromatic hybrid resins, and alkylphenol formaldehyde resins (oil-based phenol resins). These tackifier resins may be used alone or in any combination of two or more.

  The pressure-sensitive adhesive of the present invention preferably contains a silane coupling agent. By using a silane coupling agent, the adhesion between the adhesive layer and the adherend is improved, and the heat resistance and heat-and-moisture resistance may be further improved. The amount of the silane coupling agent used is preferably in the range of 0.01 to 2 parts by weight, particularly preferably in the range of 0.05 to 1 part by weight with respect to 100 parts by weight of the acrylic copolymer (A).

Examples of the silane coupling agent include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, and 3- (meta ) Alkoxysilane compounds having a (meth) acryloxy group such as acryloxypropyltributoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane;
Alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane;
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) Alkoxysilane compounds having an amino group, such as -3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane;
Alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, Alkoxysilane compounds having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyl Examples include triethoxysilane, hexamethyldisilazane, and a silicone resin having an alkoxysilyl group in the molecule (X-41-1056, manufactured by Shin-Etsu Chemical Co., Ltd., X-41-1810, manufactured by Shin-Etsu Chemical Co., Ltd.).

  The pressure-sensitive adhesive of the present invention may contain a tin catalyst in order to promote the crosslinking reaction between the hydroxyl group of the acrylic copolymer (A) and the isocyanate compound (B).

  As the tin catalyst, known tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate can be used.

  In the pressure-sensitive adhesive of the present invention, various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weathering stabilizers, plasticizers, fillers, as long as the effects of the present invention are not impaired. You may mix | blend an anti-aging agent, an antistatic agent, etc.

  In the present invention, the pressure-sensitive adhesive film has a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive of the present invention. The pressure-sensitive adhesive film can be produced, for example, by applying a pressure-sensitive adhesive on a substrate and drying it. The adhesive layer should just be provided in the at least one surface of the base material.

  When applying the adhesive, an appropriate liquid medium, for example, a hydrocarbon solvent such as toluene, xylene, hexane, heptane; an ester solvent such as ethyl acetate or butyl acetate; a ketone solvent such as acetone or methyl ethyl ketone; dichloromethane , Halogenated hydrocarbon solvents such as chloroform; ether solvents such as diethyl ether, methoxytoluene, dioxane, and other organic solvents such as hydrocarbon solvents can be added to adjust the viscosity and pressure-sensitive adhesive The viscosity can also be reduced by heating. However, it is preferable not to use water or alcohol because it may cause reaction inhibition between the acrylic copolymer (A) and the isocyanate compound (B).

  Examples of the substrate include cellophane, plastic sheet, rubber, foam, cloth, rubber cloth, resin-impregnated cloth, glass plate, wood and the like, and may be plate-like or film-like. Among these, when used for a liquid crystal display device, the substrate is preferably a film. Furthermore, the base material can be used alone, or a base material in a multilayer state formed by laminating a plurality of base materials can be used. Furthermore, what carried out the peeling process of the surface of a base material (henceforth a peeling sheet) can also be used.

  The plastic sheet is also called a plastic film. Polyvinyl alcohol film, triacetyl cellulose film, polypropylene, polyethylene, polycycloolefin, polyolefin resin film such as ethylene-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester resin film such as naphthalate, polycarbonate resin film, polynorbornene resin film, polyarylate resin film, acrylic resin film, polyphenylene sulfide resin film, polystyrene resin film, vinyl resin Film, polyamide resin film, polyimide resin film, epoxy resin film, etc. It is.

  In the present invention, the method of applying the adhesive is not particularly limited, and may be a Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. Can be mentioned. There is no restriction | limiting in particular in a drying method, What uses hot air drying, infrared rays, and the pressure reduction method is mentioned. As drying conditions, although depending on the cured form of the pressure-sensitive adhesive, the film thickness, and the selected solvent, heating with hot air at about 60 to 160 ° C. is usually sufficient.

  The pressure-sensitive adhesive film of the present invention can be obtained by (a) applying and drying a pressure-sensitive adhesive on the release-treated surface of the release sheet, and laminating a sheet-like optical member on the surface of the adhesive layer, or (b) It can be obtained by coating and drying the pressure-sensitive adhesive and laminating the release-treated surface of the release sheet on the surface of the pressure-sensitive adhesive layer.

  0.1-300 micrometers is preferable and, as for the thickness of the adhesion layer, 1-100 micrometers is more preferable. When the thickness is less than 0.1 μm, sufficient adhesive strength may not be obtained, and even when the thickness exceeds 300 μm, characteristics such as adhesive strength are often not improved further.

  Furthermore, the adhesive film of the present invention preferably has an adhesive strength of 2 to 20 N / 25 mm, more preferably 2 to 15 N / 25 mm after 1 day at 23 ° C. after being bonded to an alkali-free glass. If the adhesive strength is less than 2 N / 25 mm, the adhesive strength is insufficient as an adhesive, and there is a risk of floating or peeling. When the adhesive strength is 2 N / 25 mm or more, the adhesive strength is sufficient as an adhesive, and it can be sufficiently fixed to an adherend. Moreover, when adhesive force is larger than 20 N / 25mm, after adhering an adhesive film to a to-be-adhered body, when peeling again, there exists a possibility of destroying an to-be-adhered body.

  In this invention, it is preferable that the gel fraction of the adhesion layer of an adhesion film is 40 to 80 weight%, and 40 to 70 weight% is especially preferable. When the gel fraction is less than 40% by weight, sufficient cohesive force may not be obtained, and when it is 80% by weight or more, the stress relaxation property is lowered and a light leakage phenomenon occurs. In addition, the gel fraction as used in the field of this invention is the numerical value computed by following formula (1) after carrying out reflux extraction of the adhesive film in ethyl acetate for 5 hours, and drying for 30 minutes at 100 degreeC.

Formula (1) Gel fraction (% by weight) = (G2 / G1) × 100
G1: Weight of the adhesive layer before extraction with ethyl acetate
G2: Weight of the adhesive layer after extraction and drying with ethyl acetate

  The pressure-sensitive adhesive of the present invention can be suitably used for laminating optical members. That is, in the pressure-sensitive adhesive film of the present invention, an optical member can be preferably used as a substrate. Specific examples of the optical member include a polarizing plate, a retardation film, an elliptically polarizing film, an antireflection film, and a brightness enhancement film. A release sheet can be laminated on the other surface of the adhesive layer.

  By peeling off the release sheet covering the surface of the pressure-sensitive adhesive layer from the pressure-sensitive adhesive film thus obtained, for example, by sticking the pressure-sensitive adhesive layer to a glass member for a liquid crystal cell, “sheet-like optical member / pressure-sensitive adhesive layer / liquid crystal A liquid crystal cell member having a configuration of “cell glass member” can be obtained. In the present invention, when the optical member is a polarizing plate, it is particularly useful, and an adhesive film that does not float or peel off under high temperature and high temperature and high humidity environment can be obtained.

  As described above, the polarizing plate may be composed of a polarizing film alone, but a polarizing film and a viewing angle widening film are preferably integrated. In this case, the thickness of the adhesive layer is usually about 5 to 100 μm, preferably 10 to 50 μm.

  The pressure-sensitive adhesive of the present invention is suitable as a pressure-sensitive adhesive for optical members, as well as general labels and seals, paints, elastic wall materials, waterproof coating materials, flooring materials, tackifiers, pressure-sensitive adhesives, and pressure-sensitive adhesives for laminated structures. Agent, sealing agent, molding material, coating agent for surface modification, binder (magnetic recording medium, ink binder, casting binder, fired brick binder, graft material, microcapsule, glass fiber sizing, etc.), urethane foam (rigid, semi-rigid) , Soft), urethane RIM, UV / EB curable resin, high solid paint, thermosetting elastomer, microcellular, textile processing agent, plasticizer, sound absorbing material, vibration damping material, surfactant, gel coat agent, resin for artificial marble , Impact resistance agent for artificial marble, resin for ink, film (laminate adhesive, protective film, etc.), for laminated glass Fat, reactive diluent, various molding materials, elastic fiber, artificial leather, as a raw material for synthetic leather, can also very effectively used as various resin additives and a raw material thereof or the like.

  EXAMPLES Next, although an Example of this invention is shown and it demonstrates still in detail, this invention is not limited by these. In the examples, “part” means “part by weight”, and “%” means “% by weight”. In the following synthesis examples, for convenience, a copolymer component having a weight average molecular weight of 300,000 or more is referred to as “high molecular weight component (H)”, and a copolymer component having a weight average molecular weight of less than 300,000 is referred to as “low high molecular weight component (L ) ”. Further, the acrylic copolymer (A) was assigned a serial number as “A” regardless of whether or not it was an embodiment of the present invention.

(Synthesis Example 1)
In a reaction vessel (hereinafter simply referred to as “reaction vessel”) equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 89 parts of butyl acrylate, 10 parts of methyl acrylate, 2 parts of acrylic acid -1 part hydroxyethyl, 130 parts acetone, 0.025 part AIBN (2,2'-azobisisobutyronitrile, hereinafter referred to as "AIBN") are charged, and the air in the reaction vessel is filled with nitrogen gas. Replaced. Thereafter, while stirring under a nitrogen atmosphere, this reaction solution is reacted at a reflux temperature for 2 hours until the conversion becomes 45% to obtain a mixed solution of a copolymer having a weight average molecular weight of 1.6 million and a monomer. It was. Next, 140 parts of ethyl acetate and 0.2 part of V-65 (2,2′-azobis (2,4-dimethylvaleronitrile), hereinafter referred to as “V-65”) manufactured by Wako Pure Chemical Industries, Ltd. are added. The mixture was reacted for 2 hours, 0.2 parts of V-65 was further added, and further reacted for 6 hours until the conversion rate was 90% or more to obtain a solution of the copolymer (A1).

  The copolymer (A1) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-1) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-1), the high molecular weight component (H2-1) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-1) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-1) / (L2-1) = 50/50.

(Synthesis Example 2)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion was 35% in the same manner as in Synthesis Example 1-1. It was made to react for 1.5 hours until it became, and the mixed solution of the copolymer and monomer whose weight average molecular weight is 1.6 million was obtained. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A2) was obtained.

  The copolymer (A2) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-2) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-2), the high molecular weight component (H2-2) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-2) has a weight average molecular weight of 90,000, and the area ratio of the two Was (H2-2) / (L2-2) = 40/60.

(Synthesis Example 3)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion was 55% as in Synthesis Example 1-1. The mixture was reacted for 2.5 hours until a mixture solution of a copolymer having a weight average molecular weight of 1.6 million and a monomer was obtained. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A3) was obtained.

  The copolymer (A3) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-3) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-3), the high molecular weight component (H2-3) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-3) has a weight average molecular weight of 70,000, and the area ratio of the two Was (H2-3) / (L2-3) = 60/40.

(Synthesis Example 4)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 90 parts of ethyl acetate, and 0.025 part of AIBN, and the conversion was 45 as in Synthesis Example 1-1. It was made to react for 0.8 hours until it became%, and the mixed solution of the copolymer and monomer whose weight average molecular weight is 1 million was obtained. Next, 180 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A4) was obtained.

  The copolymer (A4) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-4) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-4), the high molecular weight component (H2-4) has a weight average molecular weight of 1,000,000, the low molecular weight component (L2-4) has a weight average molecular weight of 60,000, and the area ratio of the two Was (H2-4) / (L2-4) = 50/50.

(Synthesis Example 5)
A reaction vessel was charged with 89.4 parts of butyl acrylate, 10 parts of methyl acrylate, 0.6 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and converted in the same manner as in Synthesis Example 1-1. The reaction was continued for 2 hours until the rate reached 45% to obtain a mixed solution of a copolymer and a monomer having a weight average molecular weight of 1.6 million. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A5) was obtained.

  The copolymer (A5) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-5) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-5), the high molecular weight component (H2-5) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-5) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-5) / (L2-5) = 50/50.

(Synthesis Example 6)
A reaction vessel was charged with 88.5 parts of butyl acrylate, 10 parts of methyl acrylate, 1.5 parts of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and converted in the same manner as in Synthesis Example 1-1. The mixture was allowed to react for 2 hours until the rate reached 45% to obtain a mixed solution of a copolymer and a monomer having a weight average molecular weight of 1,650,000. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A6) was obtained.

  The copolymer (A6) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-6) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-6), the high molecular weight component (H2-6) has a weight average molecular weight of 1,650,000, the low molecular weight component (L2-6) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-6) / (L2-6) = 50/50.

(Synthesis Example 7)
A reaction vessel was charged with 84 parts of butyl acrylate, 5 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 120 parts of acetone, and 0.025 part of AIBN, and the conversion was 50% in the same manner as in Synthesis Example 1-1. It was made to react for 2.3 hours until it became, and the mixed solution of the copolymer and monomer whose weight average molecular weight is 1.6 million was obtained. Next, 5 parts of butyl acrylate, 5 parts of methyl acrylate, 150 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added, and the conversion rate was The mixture was further reacted for 6 hours until it reached 90% or more to obtain a solution of copolymer (A7).

  The copolymer (A7) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-7) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-7), the high molecular weight component (H2-7) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-7) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-7) / (L2-7) = 50/50.

(Synthesis Example 8)
A reaction vessel was charged with 84 parts of butyl acrylate, 5 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 90 parts of acetone, and 0.025 part of AIBN, and the conversion was 50% in the same manner as in Synthesis Example 1-1. It was made to react for 2.3 hours until it became, and the mixed solution of the copolymer and monomer whose weight average molecular weight is 1.8 million was obtained. Next, 10 parts of methyl methacrylate, 180 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added until the conversion reached 90% or more. The reaction was further continued for 6 hours to obtain a solution of copolymer (A8).

  The copolymer (A8) shows two independent peaks in the GPC emission curve, and a high molecular weight component (H1-8) having a weight average molecular weight of 1.8 million and a low molecular weight component having a weight average molecular weight of 40,000 ( L1-8), and the area ratio of the high molecular weight component (H1-8) to the low molecular weight component (L1-8) was (H1-8) / (L1-8) = 50/50.

(Synthesis Example 9)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion was 45% in the same manner as in Synthesis Example 1-1. The reaction was continued for 2 hours until a mixture solution of a copolymer having a weight average molecular weight of 1.6 million and a monomer was obtained. Next, 100 parts of ethyl acetate and 0.2 part of AIBN were added and reacted for 2 hours. Further, 0.2 part of AIBN was further added, and further reacted for 6 hours until the conversion reached 90% or more. A solution of A9) was obtained.

  The copolymer (A9) shows a continuous peak having no clear minimum in GPC, a high molecular weight component (H3-9) on the high molecular weight side having a molecular weight of 300,000 or more, and a low molecular weight side having a molecular weight of less than 300,000. Low molecular weight component (L3-9), the high molecular weight component (H3-9) has a weight average molecular weight of 1.6 million, the low molecular weight component (L3-9) has a weight average molecular weight of 120,000, and the area ratio of the two Was (H3-9) / (L3-9) = 50/50.

(Synthesis Example 10)
A reaction vessel was charged with 88.5 parts of butyl acrylate, 10 parts of methyl acrylate, 1.5 parts of 2-hydroxyethyl acrylate, 90 parts of ethyl acetate, 0.025 part of AIBN, and in the same manner as in Synthesis Example 1-1, The reaction was allowed to proceed for 8 hours until the conversion reached 95% or more to obtain a solution of a high molecular weight copolymer (H2-10) having a weight average molecular weight of 1,000,000.

  In another reaction vessel, 89.4 parts of butyl acrylate, 10 parts of methyl acrylate, 0.6 part of 2-hydroxyethyl acrylate, 150 parts of MEK, 0.2 part of AIBN were charged in the same manner as in Synthesis Example 1-1. The reaction was allowed to proceed for 8 hours until the conversion reached 95% or more to obtain a solution of a low molecular weight copolymer (L2-10) having a weight average molecular weight of 60,000.

  Next, the weight ratio of the high molecular weight copolymer (H2-10) to the low molecular weight copolymer (L2-10) is (H2-10) / (L2-10) = 50/50 (non-volatile content conversion). Both copolymers were mixed so that (A-10) solution was obtained, and GPC was measured. The area ratio of the high molecular weight copolymer (H2-10) and the low molecular weight copolymer (L2-10) was (H2-10) / (L2-10) = 50/50.

(Synthesis Example 11)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion was 70% in the same manner as in Synthesis Example 1-1. It was made to react for 4.5 hours until it became, and the mixed solution of the copolymer and monomer whose weight average molecular weight is 1.6 million was obtained. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A11) was obtained.

  The copolymer (A11) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-11) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-11), the high molecular weight component (H2-11) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-11) has a weight average molecular weight of 30,000, and the area ratio of the two. Was (H2-11) / (L2-11) = 75/25.

(Synthesis Example 12)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion rate was 25% in the same manner as in Synthesis Example 1-1. It was made to react for 0.8 hours until it became, and the mixed solution of the copolymer and monomer whose weight average molecular weight was 150,000 was obtained. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A12) was obtained.

  The copolymer (A12) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-12) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-12), the high molecular weight component (H2-12) has a weight average molecular weight of 150,000, the low molecular weight component (L2-12) has a weight average molecular weight of 110,000, and the area ratio of the two. Was (H2-12) / (L2-12) = 30/70.

(Synthesis Example 13)
A reaction vessel was charged with 89.8 parts of butyl acrylate, 10 parts of methyl acrylate, 0.2 part of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and converted in the same manner as in Synthesis Example 1-1. The reaction was continued for 2 hours until the rate reached 45% to obtain a mixed solution of a copolymer and a monomer having a weight average molecular weight of 1.6 million. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A13) was obtained.

  The copolymer (A13) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-13) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-13), the high molecular weight component (H2-13) has a weight average molecular weight of 1.6 million, the low molecular weight component (L2-11) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-13) / (L2-13) = 50/50.

(Synthesis Example 14)
A reaction vessel was charged with 87 parts of butyl acrylate, 10 parts of methyl acrylate, 3 parts of 2-hydroxyethyl acrylate, 130 parts of acetone, and 0.025 part of AIBN, and the conversion was 45% in the same manner as in Synthesis Example 1-1. The mixture was allowed to react for 2 hours until a mixture solution of a copolymer having a weight average molecular weight of 1,650,000 and a monomer was obtained. Next, 140 parts of ethyl acetate and 0.2 part of V-65 were added and reacted for 2 hours, and further 0.2 part of V-65 was added and reacted for another 6 hours until the conversion reached 90% or more. A solution of copolymer (A14) was obtained.

  The copolymer (A14) shows a continuous peak having a minimum value at a molecular weight of 300,000 in GPC, a high molecular weight component (H2-14) on the higher molecular weight side than this minimum value, and a lower molecular weight side than the minimum value. Low molecular weight component (L2-14), the high molecular weight component (H2-14) has a weight average molecular weight of 1,650,000, the low molecular weight component (L2-14) has a weight average molecular weight of 80,000, and the area ratio of the two Was (H2-14) / (L2-14) = 50/50.

(Synthesis Example 15)
A reaction vessel was charged with 89 parts of butyl acrylate, 10 parts of methyl acrylate, 1 part of 2-hydroxyethyl acrylate, 90 parts of ethyl acetate, and 0.025 part of AIBN, and the conversion was 95 as in Synthesis Example 1-1. It was made to react for 8 hours until it became more than%, and the solution of the copolymer (A15) whose weight average molecular weight is 1 million was obtained.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured using GPC “LC-GPC system” manufactured by Shimadzu Corporation. GPC is liquid chromatography in which a substance dissolved in a solvent (THF; tetrahydrofuran) is separated and quantified by the difference in molecular size, and the weight average molecular weight (Mw) is determined in terms of polystyrene.
Device name: LC-GPC system “Prominence” manufactured by Shimadzu Corporation
Column: Tosoh Co., Ltd. 4 GMHXL and Tosoh Co., Ltd. HXL-H 1 were connected.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min
Column temperature: 40 ° C

BA: butyl acrylate MA: methyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate

Example 1
Trimethylolpropane adduct (XDI / TMP) of xylylene diisocyanate as an isocyanate compound (B) with respect to 100 parts of the acrylic copolymer (A1) in the copolymer solution obtained in Synthesis Example 1. 2 parts were blended, and ethyl acetate was further added as a solvent to adjust the nonvolatile content to 20% to obtain a pressure-sensitive adhesive.

  The pressure-sensitive adhesive was applied on a release layer of a release sheet made of polyethylene terephthalate having a thickness of 38 μm and dried to a thickness of 25 μm, and then dried at 100 ° C. for 2 minutes for adhesion. A layer was formed. Next, one surface of a polarizing plate having a multilayer structure in which both sides of a polyvinyl alcohol (PVA) polarizer are sandwiched between triacetyl cellulose-based protective films (hereinafter referred to as “TAC film”) is bonded to this adhesive layer. An adhesive film having a configuration of “/ adhesive layer / TAC film / PVA / TAC film” was obtained. Subsequently, the obtained adhesive film was aged for one week under the conditions of a temperature of 35 ° C. and a relative humidity of 55%, to obtain an adhesive film in which the adhesive layer was covered with a release film.

(Examples 2 to 17, Comparative Examples 1 to 5)
According to the weight ratio in Table 3, a pressure-sensitive adhesive was obtained in the same manner as in Example 1. Further, an adhesive film in which the adhesive layer was coated with a release film was obtained in the same manner as in Example 1.

  The adhesive films obtained in Examples 1 to 17 and Comparative Examples 1 to 5 were evaluated by the following methods. The results are shown in Table 3.

(1) Heat resistance and wet heat resistance The adhesive film was cut into 160 mm width and 120 mm length, the release sheet was peeled off, and it was attached to non-alkali glass using a laminator. Subsequently, the glass plate to which the adhesive film was attached was held in an autoclave at 50 ° C. and 5 atm for 20 minutes to adhere to the glass plate to obtain a laminate of the adhesive film and the glass plate. As an evaluation of heat resistance, foaming, floating, and peeling after the laminate was allowed to stand at 85 ° C. for 500 hours were visually observed. In addition, as an evaluation of heat and moisture resistance, foaming, floating, and peeling were observed visually after the laminate was left at 60 ° C. and a relative humidity of 95% for 500 hours. The heat resistance and heat-and-moisture resistance were evaluated based on the following three-stage evaluation criteria.
A: “No foaming, floating or peeling is observed, and there is no problem in practical use”
○: “Bubbling, floating or peeling of 0.5 mm or less is recognized, but there is no practical problem”
×: “There is foaming, floating and peeling on the whole surface, which is not practical”

(2) Light leakage The adhesive film is cut into 160 mm width and 120 mm length, the release sheet is peeled off, and a laminator is attached so that the absorption axes of the polarizing plates of the two adhesive films are perpendicular to both sides of the alkali-free glass. Used to stick. Subsequently, the glass plate to which the adhesive film was attached was held in an autoclave at 50 ° C. and 5 atm for 20 minutes to adhere to the glass plate to obtain a laminate of the adhesive film and the glass plate. The laminate was allowed to stand at 85 ° C. for 500 hours, and then light leakage when light was transmitted through the polarizing plate was visually observed. The light leakage was evaluated based on the following three evaluation criteria.
A: “No whitening is observed and there is no practical problem at all”
○: “Slight whitening is recognized, but there is no practical problem”
×: “There is whitening on the entire surface and is not practical”

(3) Removability (reworkability)
The pressure-sensitive adhesive film was cut to a size of 25 mm wide and 150 mm long, the release sheet was peeled off, and attached to non-alkali glass using a laminator. Subsequently, it was held in an autoclave at 50 ° C. and 5 atm for 20 minutes to be in close contact with the glass plate. After leaving this test piece at 85 ° C. for 3 hours, a 180 ° peel test is performed in a 23 ° C. and 50% relative humidity environment using a tensile tester to peel it off at a rate of 300 mm / min in the direction of 180 °. Then, the fogging of the glass surface after peeling was visually observed and evaluated based on the following two-stage evaluation criteria.
○: “No glue residue or cloudiness is observed and there is no practical problem”
×: “Adhesive residue, cloudiness is recognized and impractical”

(4) Indentation The adhesive film is cut into a size of 50 mm width and 50 mm length, the release sheet is placed on the top surface and allowed to stand on the glass, and a stainless steel ball having a weight of 500 g is allowed to stand in the center of the adhesive film. It was. After holding for 1 minute or 30 seconds, the stainless steel sphere was removed, and the imprints on the adhesive film were visually observed and evaluated based on the following evaluation criteria.
A: “The trace after holding the stainless steel ball for 1 minute completely disappears after 24 hours”
○: “A trace after holding a stainless steel ball for 1 minute does not completely disappear after 24 hours, but a trace after holding for 30 seconds completely disappears after 24 hours”
X: “The trace after holding the stainless steel ball for 30 seconds does not completely disappear after 24 hours”

XDI / TMP: Trimethylolpropane adduct of xylylene diisocyanate (number of isocyanate groups: 3)
TDI / TMP: Trimethylolpropane adduct of tolylene diisocyanate (number of isocyanate groups: 3)
Coronate 2770: Allophanate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., number of isocyanate groups: 2)
KE-311: Rosin tackifying resin (Arakawa Chemical Industries)

As shown in Examples 1 to 17 in Table 3, it can be seen that the pressure-sensitive adhesive of the present invention is excellent in heat resistance, moisture and heat resistance, light leakage, removability, and indentation. On the other hand, in Comparative Examples 1-5, it turns out that any item is defective and has a practical problem or is unpractical.
The pressure-sensitive adhesive of the present invention has excellent characteristics such as heat resistance, heat-and-moisture resistance, light leakage, removability, and indentation required for a pressure-sensitive adhesive for optical members. Particularly in polarizing plate bonding applications, light leakage, which is an optical characteristic, is regarded as important, and the required performance has become increasingly severe as the display becomes larger. Therefore, the pressure-sensitive adhesive of the present invention is particularly useful because it can exhibit pressure-sensitive adhesive properties that have been difficult so far as described above.

Claims (12)

A pressure-sensitive adhesive containing an acrylic copolymer (A) and an isocyanate compound (B), wherein the copolymer (A) is
(1) Copolymerized 0.5 to 2.0% by weight of a monomer (a) containing a hydroxyl group and another monomer (b) copolymerizable with (a). Yes (provided that the total of (a) and (b) is 100% by weight),
(2) including a high molecular weight component (H) and a low molecular weight component (L);
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 Low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak and the low molecular weight component (L1) peak is
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a weight average molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
A pressure-sensitive adhesive.   The pressure-sensitive adhesive according to claim 1, comprising 0.05 to 5 parts by weight of an isocyanate compound (B) with respect to 100 parts by weight of the acrylic copolymer (A).   The pressure-sensitive adhesive according to claim 1 or 2, wherein the isocyanate compound (B) comprises a compound (B-1) having two isocyanate groups in the molecule.   Furthermore, the adhesive in any one of Claims 1-3 containing tackifying resin. The acrylic copolymer (A) comprises a monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the (a). , By radical copolymerization until the polymerization conversion is 30 to 70%, a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000 is synthesized,
Subsequently, a polymerization initiator is added, It is a thing obtained by further radical-copolymerizing said (a) and (b) until the polymerization conversion rate will be 80 to 100%, The claim in any one of Claims 1-4. Adhesive. The acrylic copolymer (A) comprises a monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the (a). , By radical copolymerization until the polymerization conversion is 30 to 70%, a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000 is synthesized,
Subsequently, the monomer (b) is further added, and (a) and (b) are further obtained by radical copolymerization until the polymerization conversion rate becomes 80 to 100%. The pressure-sensitive adhesive according to crab. A method for producing a pressure-sensitive adhesive comprising the following (I) to (III):
(I) A monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the above (a) have a polymerization conversion rate of 30 to 30%. Radical copolymerization to 70% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000 (provided that the total of (a) and (b) is 100% by weight) Do);
(II) Next, a polymerization initiator is added, and the above (a) and (b) are further radically copolymerized until the polymerization conversion becomes 80 to 100%,
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 The low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak to the low molecular weight component (L1) peak is:
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
Obtaining an acrylic copolymer (A) comprising a high molecular weight component (H) and a low molecular weight component (L); and (III) the acrylic copolymer (A) and an isocyanate compound (B). Mixing. A method for producing a pressure-sensitive adhesive comprising the following (I) to (III):
(I) A monomer (a) containing 0.5 to 2.0% by weight of a hydroxyl group and another monomer (b) copolymerizable with the above (a) have a polymerization conversion rate of 30 to 30%. Radical copolymerization to 70% to obtain a copolymer containing a high molecular weight component having a weight average molecular weight of 700,000 to 2,200,000;
(II) Then, the monomer (b) is further added, and the above (a) and (b) are further radically copolymerized until the polymerization conversion becomes 80 to 100% (provided that (a) and (b) Of 100% by weight),
(2-1) The peak of the high molecular weight component (H1) having a weight average molecular weight of 700,000 to 2,200,000 completely independent on the discharge curve in gel permeation chromatography, and the weight average molecular weight of 10,000 to 150,000 The low molecular weight component (L1) peak, and the area ratio of the high molecular weight component (H1) peak to the low molecular weight component (L1) peak is:
(H1) / (L1) = 65/35 to 35/65, or
(2-2) The peak of the high molecular weight component (H2) having a weight average molecular weight of 700,000 to 2,200,000 and the weight average molecular weight of 10,000 to 15 located on both sides of the minimum value of the discharge curve in gel permeation chromatography The low molecular weight component (L2) peak and the area ratio of the high molecular weight component (H2) peak to the low molecular weight component (L2) peak is (H2) / (L2) = 65 / 35-35 / 65, or
(2-3) In gel permeation chromatography, a peak of a high molecular weight component (H3) having a weight average molecular weight of 700,000 to 2,200,000 consisting of polymer molecules having a molecular weight of 300,000 or more, and a polymer having a molecular weight of less than 300,000 A low molecular weight component (L3) peak composed of molecules and having a weight average molecular weight of 10,000 to 150,000, and an area ratio between the high molecular weight component (H3) peak and the low molecular weight component (L3) peak is ( H3) / (L3) = 65/35 to 35/65,
Obtaining an acrylic copolymer (A) comprising a high molecular weight component (H) and a low molecular weight component (L); and (III) the acrylic copolymer (A) and an isocyanate compound (B). Mixing. A pressure-sensitive adhesive obtained by the production method according to claim 7 or 8.   A pressure-sensitive adhesive film comprising a base material and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive according to claim 1. The pressure-sensitive adhesive film according to claim 10, wherein the substrate is an optical member. The pressure-sensitive adhesive film according to claim 11, wherein the optical member is a polarizing plate.