JP7158385B2 - Adhesive composition and adhesive film - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive composition and an adhesive film.

Image display devices such as optical films used in liquid crystal displays, liquid crystal displays, plasma displays, organic EL (electroluminescence) displays, and touch panels are protected from surface protection (for example, from scratches, dust, contamination, and corrosion during transportation, storage, and processing). protection), anti-glare, anti-reflection, anti-scattering (anti-scattering of adherends), etc.

This functional film is an adhesive film having an adhesive layer for attachment to an image display device on one side of a base film and a functional coating layer provided on the other side as needed. is assumed to be in the form Before being attached to the surface of the image display device, it is attached to a release film. Optical films used in liquid crystal display devices, such as polarizing plates and retardation plates, are attached to liquid crystal cells using an adhesive.

The adhesive has excellent optical properties and is relatively easy to design. agent is used. Further, an isocyanate-based cross-linking agent is used as the cross-linking agent in order to obtain durability in an environment of high temperature and high humidity.

Here, the (meth)acrylic pressure-sensitive adhesive has a problem that contaminants derived from the pressure-sensitive adhesive layer remain on the adherend when the pressure-sensitive adhesive film is peeled off from the adherend. This is considered to be due to the low molecular weight components produced during the production of the (meth)acrylic acid ester copolymer. Furthermore, such low-molecular-weight components also cause a problem of excessively increasing adhesive force when the adhesive is heated. When the adhesive is heated due to the environment in which the adhesive film is attached to the article, the adhesive strength of the adhesive increases and the adhesive adheres strongly to the adherend, and the adhesive film is peeled off even after the purpose of use of the adhesive film has ended. becomes difficult. Furthermore, even if it can be peeled off, the adhesive remains on the adherend and contaminates the adherend. Therefore, there is a demand for a (meth)acrylic acid ester-based copolymer containing less low-molecular-weight components.

In general, (meth)acrylic acid ester copolymers are produced by free radical polymerization, but it is difficult to obtain homogeneity of the copolymer composition, and as a result, low molecular weight components (oligomers) are produced. generate a lot. Therefore, in Patent Document 1, it is proposed to use a (meth)acrylic acid ester-based copolymer produced by a living radical polymerization method in an adhesive composition (Patent Document 1 (page 18, 5 to 10 , lines 24-26)).

Further, it is known that when a (meth)acrylic acid ester-based copolymer obtained by a living radical polymerization method is used, cross-linking is delayed and heavy exfoliation occurs over time (Patent Document 2 (Comparative Example 1, See Comparative Example 5)). Delayed crosslinking requires a long curing period, resulting in poor productivity of the adhesive film, and heavy release increases the storage stability of the adhesive film and increases the workload during use. Therefore, in Patent Document 2, it is proposed to use a pressure-sensitive adhesive composition comprising a (meth)acrylic acid ester-based copolymer obtained by a living radical polymerization method, an isocyanate-based cross-linking agent, and an organic tin compound. (See Patent Document 2 (claim 1)).

WO2007/119884 JP 2014-31442 A

However, even in the pressure-sensitive adhesive composition described in Patent Document 2, the effect of suppressing heavy peeling is not sufficient, and there is room for further investigation. Furthermore, although Patent Document 2 proposes the use of an organotin compound, there is a need for a cross-linking accelerator to replace the organotin compound due to concerns about its toxicity.

The present invention has been made in view of the above circumstances, and aims to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having a short curing period, low staining property, and suppressed heavy release. aim.

The pressure-sensitive adhesive composition of the present invention, which was able to solve the above problems, comprises (A) a (meth)acrylic copolymer having a reactive functional group, (B) an isocyanate-based cross-linking agent, and (C) a metal and a chelate compound, the (A) (meth)acrylic copolymer is obtained by living radical polymerization, has a weight average molecular weight of 200,000 to 2,000,000, and has a molecular weight distribution (PDI) of It is characterized by being less than 3.0.

The pressure-sensitive adhesive composition of the present invention contains (C) a metal chelate compound, so that even when a copolymer obtained by living radical polymerization is used, the curing period is short, the staining property is low, and , a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer in which heavy release is suppressed can be obtained.

The pressure-sensitive adhesive composition can be suitably used for optics. The present invention also includes a pressure-sensitive adhesive film having a base film and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The present invention also includes an image display device provided with the pressure-sensitive adhesive film.

The pressure-sensitive adhesive composition of the present invention has a short curing period when forming a pressure-sensitive adhesive layer. In addition, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention has low staining properties and is suppressed from being heavily released from the release film.

An example of a preferred embodiment of the present invention will be described below. However, the following embodiments are merely examples. The present invention is by no means limited to the following embodiments.

In the present invention, "(meth)acrylic" means "at least one of acrylic and methacrylic". "(Meth)acrylate" means "at least one of acrylate and methacrylate". "(Meth)acryloyl" means "at least one of acryloyl and methacryloyl". A "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in the molecule. A “structural unit derived from a vinyl monomer” refers to a structural unit in which a radically polymerizable carbon-carbon double bond of a vinyl monomer is polymerized to form a carbon-carbon single bond. The “structural unit derived from (meth)acrylate” refers to a structural unit in which the radically polymerizable carbon-carbon double bond of (meth)acrylate is polymerized to form a carbon-carbon single bond. A “structural unit derived from a (meth)acrylic monomer” refers to a structural unit in which a radically polymerizable carbon-carbon double bond of a (meth)acrylic monomer is polymerized to form a carbon-carbon single bond. A “structural unit derived from a vinyl monomer” refers to a structural unit in which a radically polymerizable carbon-carbon double bond of a vinyl monomer is polymerized to form a carbon-carbon single bond.

<1. Adhesive Composition>
The adhesive composition of the present invention contains (A) a (meth)acrylic copolymer having a reactive functional group, (B) an isocyanate cross-linking agent, and (C) a metal chelate compound. The (A) (meth)acrylic copolymer is obtained by living radical polymerization, has a weight average molecular weight of 200,000 to 2,000,000, and a molecular weight distribution (PDI) of less than 3.0. be.

By blending (C) a metal chelate compound in the pressure-sensitive adhesive composition of the present invention, the curing period for forming the pressure-sensitive adhesive layer can be shortened. In addition, the pressure-sensitive adhesive composition of the present invention, by blending (C) a metal chelate compound, even when using a copolymer obtained by living radical polymerization, high release from the release film or the adherend. can be suppressed.

Each component and the like of the pressure-sensitive adhesive composition of the present invention will be described below.

((A) a (meth)acrylic copolymer having a reactive functional group)
The (A) (meth)acrylic copolymer having a reactive functional group (hereinafter sometimes simply referred to as "(A) copolymer") used in the present invention is obtained by living radical polymerization. is a (meth)acrylic copolymer having a weight average molecular weight of 200,000 to 2,000,000, a molecular weight distribution (Mw/Mn) of less than 3.0, and having a reactive functional group.

The (meth)acrylic copolymer may be any copolymer whose main component (50% by mass or more) is a structural unit derived from a (meth)acrylic monomer, and vinyl monomers other than (meth)acrylic monomers can contain structural units derived from The content of the structural unit derived from the (meth)acrylic monomer in the copolymer (A) is preferably 80% by mass or more, more preferably 90% by mass or more, based on 100% by mass of the entire copolymer. The copolymer (A) may be composed only of structural units derived from (meth)acrylic monomers.

The (A) copolymer is preferably a (meth)acrylate copolymer ((meth)acrylate copolymer). The (meth)acrylate copolymer may be a copolymer having a structural unit derived from (meth)acrylate as a main component (50% by mass or more), and is derived from a vinyl monomer other than (meth)acrylate. It can contain structural units. The (meth)acrylate is an ester compound produced from (meth)acrylic acid and a compound having a hydroxy group. The content of structural units derived from (meth)acrylate in the copolymer (A) is preferably 80% by mass or more, more preferably 90% by mass or more, based on 100% by mass of the entire copolymer. The copolymer (A) may be composed only of structural units derived from (meth)acrylate.

The reactive functional group is a functional group capable of reacting with an isocyanate group of the (B) isocyanate-based cross-linking agent described later. Examples of the reactive functional group include one or more selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a phosphine group and an epoxy group. , preferably hydroxy and/or carboxy groups.

The amount of reactive functional groups per 100 g of the (A) copolymer is preferably 0.5 mmol/100 g or more, more preferably 5 mmol/100 g or more, still more preferably 10 mmol/100 g or more, and particularly preferably 15 mmol/100 g or more. , preferably 150 mmol/100 g or less, more preferably 100 mmol/100 g or less, still more preferably 70 mmol/100 g or less, and particularly preferably 50 mmol/100 g or less. When the amount of reactive functional groups is 0.5 mmol/100 g or more, the durability of the pressure-sensitive adhesive composition is excellent, and when it is 150 mmol/100 g or less, the adhesiveness to the adherend is excellent.

The copolymer (A) has a reactive functional group. That is, the copolymer (A) contains a structural unit (a-1) having a reactive functional group in its structure. The structural unit (a-1) having the reactive functional group may be of only one type, or may be of two or more types. The reactive functional group may be present in either a structural unit derived from a (meth)acrylic monomer (preferably a (meth)acrylate monomer) or a structural unit derived from a vinyl monomer other than the (meth)acrylic monomer. . That is, the structural unit (a-1) having a reactive functional group is a structural unit derived from a (meth)acrylic monomer (preferably a (meth)acrylate monomer) having a reactive functional group, or a reactive functional group Structural units derived from vinyl monomers other than (meth)acrylic monomers having

The content of the structural unit (structural unit (a-1) having a reactive functional group) derived from a vinyl monomer having a reactive functional group in the copolymer (A) is 100% by mass of the entire copolymer. , preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, particularly preferably 3% by mass or more, and preferably 20% by mass or less, more preferably is 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 8% by mass or less. When the content of the structural unit (a-1) is within the above range, it is possible to obtain a pressure-sensitive adhesive composition having an excellent balance between adhesion to an adherend and durability. The vinyl monomer having a reactive functional group includes vinyl monomers other than (meth)acrylic monomers having a reactive functional group and (meth)acrylic monomers having a reactive functional group.

Examples of the (meth)acrylic monomer include (b1) a (meth)acrylic monomer having no reactive functional group and (b2) a (meth)acrylic monomer having a reactive functional group. These monomers may be used alone or in combination of two or more. The (b1) (meth)acrylic monomer having no reactive functional group is preferably (b1-1) a (meth)acrylate monomer having no reactive functional group. Examples of the (b2) (meth)acrylic monomer having a reactive functional group include (b2-1) a (meth)acrylate monomer having a reactive functional group.

The (b1) (meth)acrylic monomer having no reactive functional group includes (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, and (meth)acrylates having an alkoxy group. ) acrylate, (meth)acrylate having a polyethylene glycol structural unit, (meth)acrylate having an alicyclic hydrocarbon group, (meth)acrylate having an aromatic group, (meth)acrylate having an oxygen-containing heterocyclic group, three Examples include (meth)acrylates and (meth)acrylamides having a class amino group. Among these, (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, (meth)acrylates having an alicyclic hydrocarbon group, and (meth)acrylates having an aromatic group , (meth)acrylamides are preferred.

The (meth)acrylate having a straight-chain alkyl group is preferably a (meth)acrylate having a straight-chain alkyl group having 1 to 20 carbon atoms in the straight-chain alkyl group. (Meth)acrylates having linear alkyl groups of 1 to 10 in number are more preferred. Examples of (meth)acrylates having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, and n-hexyl (meth)acrylate. , n-octyl (meth)acrylate, n-nonyl (meth)acrylate, decyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate (meth)acrylic acid linear alkyl esters such as mentioned.

The (meth)acrylate having a branched-chain alkyl group is preferably a (meth)acrylate having a branched-chain alkyl group having 3 to 20 carbon atoms in the branched-chain alkyl group. (Meth)acrylates with 3 to 10 branched alkyl groups are preferred. Examples of (meth)acrylates having a branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, 2 - (meth)acrylic acid branched chain alkyl esters such as ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate and the like.

Examples of (meth)acrylates having an alkoxy group include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

The (meth)acrylate having a polyethylene glycol structural unit includes polyethylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5)) methyl ether (meth) acrylate, polyethylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5)) ethyl ether (meth) acrylate, polyethylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5)) propyl ether (meth) acrylate, polypropylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5)) Methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5)) Ethyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 1 to 10 (preferably 1 to 5) ) propyl ether (meth)acrylate and the like.

Examples of the alicyclic hydrocarbon group include saturated monocyclic hydrocarbon groups, unsaturated monocyclic hydrocarbon groups, and bridged ring hydrocarbon groups. The (meth)acrylate having an alicyclic hydrocarbon group is preferably a compound in which an alicyclic hydrocarbon group is directly bonded to a (meth)acryloyloxy group. The (meth)acrylate having an alicyclic hydrocarbon group is preferably a (meth)acrylate having a saturated monocyclic hydrocarbon group, and has a saturated monocyclic hydrocarbon group having 6 to 12 carbon atoms (meth) ) acrylates are more preferred. The (meth)acrylate having an alicyclic hydrocarbon group includes (meth)acrylates having a saturated monocyclic hydrocarbon group such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate. Bornyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) ) acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate and the like (meth)acrylate having a bridged ring hydrocarbon group.

Examples of (meth)acrylates having an alicyclic hydrocarbon group include (meth)acrylates having a cyclic alkyl group and (meth)acrylates having a polycyclic structure. The (meth)acrylate having a cyclic alkyl group is preferably a (meth)acrylate having a cyclic alkyl group having 6 to 12 carbon atoms. The cyclic alkyl group includes a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group), and may have a chain portion. Specific examples of (meth)acrylates having a cyclic alkyl group having a monocyclic structure include (meth)acrylic acid cyclic alkyl esters such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate. be able to.

The (meth)acrylate having a polycyclic structure is preferably a (meth)acrylate having a polycyclic structure with 6 to 12 carbon atoms. The polycyclic structure includes cyclic alkyl groups having a bridged ring structure (eg, adamantyl group, norbornyl group, isobornyl group), and may also have a chain portion. Specific examples of (meth)acrylates having a polycyclic structure include bornyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-adamantyl (meth)acrylate, 2-methyl-2- adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, norbornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyloxyethyl (meth) Acrylate, dicyclopentenyloxyethyl (meth)acrylate and the like can be mentioned.

The (meth)acrylate having an aromatic group is preferably a (meth)acrylate having an aromatic group having 6 to 12 carbon atoms. Examples of the aromatic group include an aryl group, and may have a chain portion such as an alkylaryl group, an araryl group, an aryloxyalkyl group, and the like. Examples of the (meth)acrylate having an aromatic group include a compound in which an aryl group is directly bonded to a (meth)acryloyloxy group, a compound in which an aralkyl group is directly bonded to a (meth)acryloyloxy group, and a (meth)acryloyloxy group. A compound having an alkylaryl group directly bonded thereto may be mentioned. The aryl group preferably has 6 to 12 carbon atoms. The aralkyl group preferably has 6 to 12 carbon atoms. The alkylaryl group preferably has 6 to 12 carbon atoms. (Meth)acrylates having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and the like.

The (meth)acrylate having an oxygen-containing heterocyclic group is preferably a (meth)acrylate having a 4- to 6-membered oxygen-containing heterocyclic group. Specific examples of (meth)acrylates having an oxygen-containing heterocyclic group include tetrahydrofurfuryl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl- 1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, 1,3-dioxane- (Meth)acrylate and the like.

Examples of (meth)acrylates having a tertiary amino group include 2-(dimethylamino)ethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate.

Examples of the (meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, (meth)acrylamide, N-methyl(meth) Acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, N-octyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl ( meth)acrylamide, N-propoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetoneacrylamide, N-(meth)acrylylmorpholine and the like. The (meth)acrylamides are (meth)acryl monomers, but are not included in (meth)acrylate monomers.

The (b2) (meth)acrylic monomer having a reactive functional group includes a (meth)acrylic monomer having a hydroxy group (preferably a (meth)acrylate monomer), a (meth)acrylic monomer having a carboxy group (preferably ( meth)acrylate monomer), (meth)acrylic monomer having a sulfonic acid group (preferably (meth)acrylate monomer), (meth)acrylic monomer having a phosphoric acid group (preferably (meth)acrylate monomer), having an epoxy group (Meth) acrylic monomers (preferably (meth) acrylate monomers) and the like. Among these, a (meth)acrylic monomer having a hydroxy group and a (meth)acrylic monomer having a carboxy group are preferable.

Examples of the (meth)acrylic monomer having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6 - hydroxyalkyl (meth)acrylates such as hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate; (4-hydroxymethylcyclohexyl) hydroxyalkylcycloalkane (meth)acrylate such as methyl (meth)acrylate; caprolactone adduct of hydroxyalkyl (meth)acrylate; and the like. Among these, hydroxyalkyl (meth)acrylates are preferred, and (meth)acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are more preferred.

Examples of the (meth)acrylic monomer having a carboxy group include carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2 - Monomers obtained by reacting (meth)acrylates having a hydroxy group such as (meth)acryloyloxyethyl phthalate with acid anhydrides such as maleic anhydride, succinic anhydride and phthalic anhydride, and (meth)acrylic acid. . Among these, (meth)acrylic acid is preferred.

Examples of the (meth)acrylic monomer having a sulfonic acid group include ethyl sulfonate (meth)acrylate.

Examples of the (meth)acrylic monomer having a phosphoric acid group include 2-(phosphonooxy)ethyl (meth)acrylate.

Examples of (meth)acrylic acid esters having an epoxy group include glycidyl (meth)acrylate and 3,4-epoxycyclohexylmethyl (meth)acrylate.

Examples of the vinyl monomer of the (meth)acrylic monomer include (b3) a vinyl monomer other than a (meth)acrylic monomer having no reactive functional group, and (b4) a vinyl monomer other than a (meth)acrylic monomer having a reactive functional group. monomers. These monomers may be used alone or in combination of two or more.

Vinyl monomers other than the (b3) (meth)acrylic monomer having no reactive functional group include aromatic vinyl monomers, vinyl monomers containing a heterocycle, vinyl carboxylates, and vinyl monomers containing a tertiary amino group. , vinyl monomers containing quaternary ammonium bases, vinylamides, α-olefins, dienes and the like.

Examples of the aromatic vinyl monomers include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene and 1-vinylnaphthalene.
Examples of vinyl monomers containing the heterocycle include 2-vinylthiophene, N-methyl-2-vinylpyrrole, 2-vinylpyridine and 4-vinylpyridine.
Examples of the vinyl carboxylate include vinyl acetate, vinyl pivalate, and vinyl benzoate.
Examples of vinyl monomers containing a tertiary amino group include N,N-dimethylallylamine.
Vinyl monomers containing the quaternary ammonium base include N-methacryloylaminoethyl-N,N,N-dimethylbenzylammonium chloride and the like.
Examples of the vinylamides include N-vinylformamide, N-vinylacetamide, 1-vinyl-2-pyrrolidone, N-vinyl-ε-captolactam and the like.
Examples of the α-olefin include 1-hexene, 1-octene and 1-decene.
Examples of the dienes include butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene.

Examples of the (b4) vinyl monomer other than the (meth)acrylic monomer having a reactive functional group include a vinyl monomer having a hydroxy group, a vinyl monomer having a carboxy group, and a vinyl monomer containing an epoxy group.

Examples of vinyl monomers having a hydroxy group include p-hydroxystyrene and allyl alcohol.
Examples of vinyl monomers having a carboxyl group include crotonic acid, maleic acid, itaconic acid, citraconic acid, cinnamic acid, and (meth)acrylic acid.
Examples of vinyl monomers containing epoxy groups include 2-allyl oxirane, glycidyl vinyl ether, and 3,4-epoxycyclohexyl vinyl ether.

The copolymer (A) may be a random copolymer, a block copolymer, a graft copolymer, or the like.

The weight average molecular weight (Mw) of the (A) copolymer is 200,000 or more, preferably 400,000 or more, more preferably 500,000 or more, still more preferably 600,000 or more, and preferably 2,000,000 or less. It is 1,800,000 or less, more preferably 1,500,000 or less, and still more preferably 1,300,000 or less. (A) If the Mw of the copolymer is less than 200,000, the cohesive force may be insufficient, resulting in a decrease in heat resistance or contamination of the surface of the adherend. may get worse. A method for measuring the weight average molecular weight (Mw) will be described later.

The molecular weight distribution (PDI) of the (A) copolymer is less than 3.0, preferably less than 2.5, more preferably less than 2.4, and particularly preferably less than 2.0. The smaller the PDI, the narrower the width of the molecular weight distribution, the more uniform the molecular weight of the copolymer. When the value is 1.0, the narrowest molecular weight distribution. If the PDI is less than 3.0, the content of substances with a small molecular weight or a substance with a large molecular weight is low compared to the designed molecular weight of the copolymer, and the adhesive strength is improved. In the present invention, the molecular weight distribution (PDI) is a value calculated by (weight average molecular weight (Mw)) / (number average molecular weight (Mn)), and methods for measuring Mw and Mn will be described later.

The glass transition temperature (Tg) of the copolymer (A) is preferably −80° C. or higher, more preferably −70° C. or higher, and preferably 20° C. or lower, more preferably 0° C. or lower. If the glass transition temperature is −80° C. or higher, the pressure-sensitive adhesive composition will have sufficient cohesive strength, and the durability of the pressure-sensitive adhesive layer will be improved. It becomes high, peeling etc. are suppressed and durability improves.

The glass transition temperature (Tg) of the (A) copolymer is a value calculated by the following FOX formula (formula (1)). In formula (1), Tg represents the glass transition temperature (°C) of the copolymer. Tgi indicates the glass transition temperature (°C) when the vinyl monomer i forms a homopolymer. Wi indicates the mass ratio of vinyl monomer i in all vinyl monomers forming the copolymer, and ΣWi=1. i is a natural number from 1 to n.

Table 1 shows the glass transition temperatures of representative homopolymers.

The (A) copolymer is produced by radically polymerizing a vinyl monomer by a living radical polymerization method. In the conventional radical polymerization method (free radical polymerization method), not only the initiation reaction and propagation reaction, but also termination reaction and chain transfer reaction cause deactivation of the propagating end, resulting in a mixture of polymers with various molecular weights and heterogeneous compositions. tend to be easy. In the living radical polymerization method, while maintaining the simplicity and versatility of conventional radical polymerization methods, termination reaction and chain transfer are less likely to occur, and growing terminals grow without deactivation. It is easy to produce a polymer of uniform composition.

Therefore, the copolymer produced by the living radical polymerization method is considered to have the advantage that it contains few low-molecular-weight components (oligomers) and causes little contamination of adherends when used in pressure-sensitive adhesive compositions. In addition, since the reactive functional groups are uniformly distributed in the copolymer, the copolymer produced by the living radical polymerization method is more suitable for the isocyanate cross-linking agent than the copolymer produced by the free radical polymerization method. It is believed that the amount of reactive functional groups that can be reacted increases, causing delay in cross-linking and requiring a long curing period.

In the living radical polymerization method, a random copolymer can be obtained by using a mixture of the monomers (vinyl monomers) constituting the copolymer (A). A block copolymer can also be obtained by sequentially reacting vinyl monomers constituting the copolymer. For example, in the case of a diblock copolymer, the first block is first produced, and the first block is polymerized with a vinyl monomer constituting the second block; , a method of polymerizing the vinyl monomer constituting the first block into the second block; and the like. In the case of a triblock copolymer, the first block is first produced, the vinyl monomer constituting the second block is polymerized on the first block, and the vinyl monomer constituting the third block is further polymerized. and the like;

Living radical polymerization methods include a method using a transition metal catalyst such as copper, ruthenium, nickel, and iron (ATRP method); a method using a sulfur-based reversible chain transfer agent, depending on the method of stabilizing the polymerization growth terminal. (RAFT method); and a method using an organic tellurium compound (TERP method). Since the ATRP method uses an amine-based complex, it may not be possible to use unless the acidic group of the vinyl monomer having an acidic group is protected. In the RAFT method, when a variety of vinyl monomers are used, it is difficult to obtain a low molecular weight distribution, and problems such as sulfur odor and coloration may occur. Among these methods, it is preferable to use the TERP method from the viewpoint of the diversity of usable vinyl monomers, molecular weight control in the high molecular region, uniform composition, or coloring.

The TERP method is a method of polymerizing a radically polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent. 2004/072126 and the method described in WO 2004/096870.

Specific polymerization methods for the TERP method include the following (a) to (d).
(a) A method of polymerizing a vinyl monomer using an organic tellurium compound represented by formula (1).
(b) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by formula (1) and an azo polymerization initiator.
(c) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by formula (1) and an organic ditelluride compound represented by formula (2).
(d) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by formula (1), an azo polymerization initiator, and an organic ditelluride compound represented by formula (2).

［式（１）において、Ｒ¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基である。Ｒ²およびＲ³は、それぞれ独立に、水素原子または炭素数１～８のアルキル基である。Ｒ⁴は、炭素数１～８のアルキル基、アリール基、置換アリール基、芳香族ヘテロ環基、アルコキシ基、アシル基、アミド基、オキシカルボニル基、シアノ基、アリル基またはプロパルギル基である。］

[In the formula (1), R ¹ is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group. R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ⁴ is an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amido group, an oxycarbonyl group, a cyano group, an allyl group or a propargyl group. ]

［式（２）において、Ｒ¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基である。］

[In the formula (2), R ¹ is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group. ]

The group represented by R ¹ is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group, and specific examples are as follows.
Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group and heptyl. linear or branched alkyl groups such as radicals, octyl groups, and cyclic alkyl groups such as cyclohexyl groups. A linear or branched alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.
A phenyl group, a naphthyl group, etc. can be mentioned as an aryl group.
A pyridyl group, a furyl group, a thienyl group, etc. can be mentioned as an aromatic heterocyclic group.

The groups represented by R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and specific examples of each group are as follows.
Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group and heptyl. linear or branched alkyl groups such as radicals, octyl groups, and cyclic alkyl groups such as cyclohexyl groups. A linear or branched alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

The group represented by R ⁴ is an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group or It is a propargyl group, specifically as follows.
Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group and heptyl. linear or branched alkyl groups such as octyl groups, cyclic alkyl groups such as cyclohexyl groups, and the like. A linear or branched alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.
A phenyl group, a naphthyl group, etc. can be mentioned as an aryl group. A phenyl group is preferred.
Examples of the substituted aryl group include a phenyl group having a substituent, a naphthyl group having a substituent, and the like. Substituents of the aryl group having a substituent include, for example, a halogen atom, a hydroxy group, an alkoxy group, an amino group, a nitro group, a cyano group, and a carbonyl-containing group represented by —COR ⁴¹ (R ⁴¹ is the number of carbon atoms 1 to 8 alkyl groups, aryl groups, C 1 to 8 alkoxy groups or aryloxy groups), sulfonyl groups, trifluoromethyl groups and the like. Moreover, it is preferable that one or two of these substituents are substituted.
A pyridyl group, a furyl group, a thienyl group, etc. can be mentioned as an aromatic heterocyclic group.
The alkoxy group is preferably a group in which an alkyl group having 1 to 8 carbon atoms is bonded to an oxygen atom. butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.
Acyl groups include acetyl, propionyl, and benzoyl groups.
Examples of amide groups include -CONR ⁴²¹ R ⁴²² (R ⁴²¹ and R ⁴²² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group).
The oxycarbonyl group is preferably a group represented by --COOR ⁴³ (R ⁴³ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group), such as a carboxy group, a methoxycarbonyl group, an ethoxycarbonyl group and a propoxycarbonyl group. group, n-butoxycarbonyl group, sec-butoxycarbonyl group, ter-butoxycarbonyl group, n-pentoxycarbonyl group, phenoxycarbonyl group and the like. Preferred oxycarbonyl groups include methoxycarbonyl and ethoxycarbonyl groups.
The allyl group includes -CR ⁴⁴¹ R ⁴⁴² -CR ⁴⁴³ =CR ⁴⁴⁴ R ⁴⁴⁵ (R ⁴⁴¹ and R ⁴⁴² are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴⁴³ , R ⁴⁴⁴ and R ⁴⁴⁵ are , are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, and each substituent may be connected in a cyclic structure).
The propargyl group includes —CR ⁴⁵¹ R ⁴⁵² —C≡CR ⁴⁵³ (R ⁴⁵¹ and R ⁴⁵² are a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴⁵³ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms , an aryl group or a silyl group).

Specifically, the organic tellurium compound represented by formula (1) is (methyltheranylmethyl)benzene, (methyltheranylmethyl)naphthalene, ethyl-2-methyl-2-methyltheranyl-propionate, ethyl-2-methyl -2-n-butyltheranyl-propionate, (2-trimethylsiloxyethyl)-2-methyl-2-methyltheranyl-propionate, (2-hydroxyethyl)-2-methyl-2-methyltheranyl-propionate or (3-trimethylsilylpropargyl) -2-methyl-2-methylteranyl-propionate, etc., organotellurium described in WO2004/14848, WO2004/14962, WO2004/072126, and WO2004/096870 All compounds can be exemplified.

Specifically, the organic ditelluride compound represented by formula (2) includes dimethyl ditelluride, diethyl ditelluride, di-n-propyl ditelluride, diisopropyl ditelluride, dicyclopropyl ditelluride, di -n-butyl ditelluride, di-s-butyl ditelluride, di-t-butyl ditelluride, dicyclobutyl ditelluride, diphenyl ditelluride, bis-(p-methoxyphenyl) ditelluride, bis-(p-aminophenyl) ditelluride, bis -(p-nitrophenyl)ditelluride, bis-(p-cyanophenyl)ditelluride, bis-(p-sulfonylphenyl)ditelluride, dinaphthylditelluride, dipyridylditelluride and the like can be exemplified.

As the azo polymerization initiator, any azo polymerization initiator that is commonly used in radical polymerization can be used without any particular limitation. For example, 2,2′-azobis(isobutyronitrile) (AIBN), 2,2′-azobis(2-methylbutyronitrile) (AMBN), 2,2′-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1′-azobis(1-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2′-azobisisobutyrate (MAIB), 4,4′-azobis(4-cyanovaleric acid) (ACVA), 1,1′-azobis(1-acetoxy-1-phenylethane), 2,2′-azobis(2-methylbutyramide), 2,2′-azobis(4-methoxy-2,4- dimethylvaleronitrile) (V-70), 2,2′-azobis(2-methylamidinopropane) dihydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane], 2, 2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2′-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2, 2′-azobis(N-butyl-2-methylpropionamide), 2,2′-azobis(N-cyclohexyl-2-methylpropionamide) and the like can be exemplified.

In the polymerization step, a vessel is replaced with an inert gas, and the vinyl monomer and the organic tellurium compound of formula (1) are added to the vinyl monomer for the purpose of promoting the reaction, controlling the molecular weight and molecular weight distribution, etc., depending on the type of the vinyl monomer, and further adding an azo A system polymerization initiator and/or an organic ditelluride compound of formula (2) are mixed. At this time, examples of the inert gas include nitrogen, argon, and helium. Argon and nitrogen are preferred.

In the above polymerization methods (a), (b), (c) and (d), the amount of the vinyl monomer used may be appropriately adjusted depending on the physical properties, molecular weight, etc. of the desired copolymer. It is preferable to use 200 mol to 30000 mol of the vinyl monomer per 1 mol of the organotellurium compound of (1). The molecular weight of the intended copolymer can also be increased by increasing the amount of the vinyl monomer used per 1 mol of the organotellurium compound of formula (1).

In the polymerization method (b), when the organic tellurium compound of formula (1) and an azo polymerization initiator are used in combination, the amount of the azo polymerization initiator used is usually the organic tellurium compound of formula (1) It is preferable to use 0.01 mol to 10 mol of the azo polymerization initiator per 1 mol.

In the polymerization method (c) above, when the organic tellurium compound of formula (1) and the organic ditelluride compound of formula (2) are used in combination, the amount of the organic ditelluride compound of formula (2) used is generally the formula ( It is preferable to use 0.01 mol to 100 mol of the organic ditelluride compound of formula (2) per 1 mol of the organic tellurium compound of 1).

In the polymerization method (d), when the organic tellurium compound of formula (1), the organic ditelluride compound of formula (2), and an azo polymerization initiator are used in combination, the amount of the azo polymerization initiator used is usually The amount of the azo polymerization initiator is preferably 0.01 mol to 100 mol per 1 mol in total of the organic tellurium compound of formula (1) and the organic ditelluride compound of formula (2).

The polymerization reaction can be carried out without a solvent, but may be carried out by using an aprotic or protic solvent generally used in radical polymerization and stirring the mixture. Aprotic solvents that can be used are, for example, benzene, toluene, N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, 2-butanone (methyl ethyl ketone), dioxane, propylene glycol monomethyl ether acetate, chloroform, Examples include carbon chloride, tetrahydrofuran (THF), ethyl acetate, propylene glycol monomethyl ether acetate, trifluoromethylbenzene, and the like. Examples of protic solvents include water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol or diacetone alcohol, and hexafluoroisopropanol.

The amount of the solvent to be used may be adjusted as appropriate. For example, it is preferably 0.01 ml or more, more preferably 0.05 ml or more, still more preferably 0.1 ml or more, and 50 ml or less per 1 g of the vinyl monomer. It is preferably 10 ml or less, more preferably 1 ml or less.

The mixture is then stirred. The reaction temperature and reaction time may be appropriately adjusted depending on the molecular weight or molecular weight distribution of the resulting copolymer, but the mixture is usually stirred at 0°C to 150°C for 1 minute to 100 hours. The TERP method can obtain high yields and precise molecular weight distributions even at low polymerization temperatures and short polymerization times. At this time, the pressure is usually normal pressure, but may be pressurized or reduced.

After completion of the polymerization reaction, the reaction mixture obtained can be subjected to the removal of the solvent used, residual vinyl monomers, etc. by a usual means of isolation and purification, and the intended copolymer can be isolated and purified. Moreover, the reaction mixture may be used as it is in the pressure-sensitive adhesive composition as long as it does not interfere with the physical properties of the pressure-sensitive adhesive composition.

The growing terminal of the copolymer obtained by the polymerization reaction is in the form of -TeR ¹ (wherein R ¹ is the same as described above), and is deactivated by the operation in the air after the completion of the polymerization reaction. , tellurium atoms may remain. Since a copolymer having a tellurium atom remaining at the end thereof is colored or has poor thermal stability, it is preferable to remove the tellurium atom.

Methods for removing tellurium atoms include radical reduction methods using tributylstannane or thiol compounds; adsorption methods using activated carbon, silica gel, activated alumina, activated clay, molecular sieves, polymer adsorbents, etc.; ion exchange resins, etc. Method of adsorbing metals: Hydrogen peroxide solution or peroxides such as benzoyl peroxide are added, air or oxygen is blown into the system to oxidize and decompose the tellurium atoms at the ends of the copolymer, washing with water or appropriate A liquid-liquid extraction method or solid-liquid extraction method that removes residual tellurium compounds by combining solvents; a purification method in a solution state such as ultrafiltration that extracts and removes only those with a specific molecular weight or less; , or a combination of these methods can be used. In addition, in the copolymer produced by the TERP method, metal compounds derived from the chain transfer agent may remain as impurities (exceeding 0 ppm). The tellurium content in the copolymer produced by the TERP method is preferably 1000 ppm or less, more preferably 400 ppm or less, and even more preferably 200 ppm or less.

((B) isocyanate cross-linking agent)
The pressure-sensitive adhesive composition contains (B) an isocyanate-based cross-linking agent. The isocyanate-based cross-linking agent is a compound having two or more isocyanate groups (including an isocyanate regenerative functional group temporarily protected by a blocking agent or quantization of the isocyanate group) in one molecule. The isocyanate-based cross-linking agent (B) may be used alone or in combination of two or more.

Examples of isocyanate-based cross-linking agents include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.
More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct, trimethylolpropane/hexamethylene diisocyanate trimer adduct, Isocyanate adducts such as isocyanurate hexamethylene diisocyanate; trimethylolpropane adducts of xylylene diisocyanate; trimethylolpropane adducts of hexamethylene diisocyanate; polyether polyisocyanates, polyester polyisocyanates, and combinations thereof with various polyols Polyisocyanate multifunctionalized with adducts, isocyanurate bonds, biuret bonds, allophanate bonds, etc. can be used. Among these, it is preferable to use an aliphatic isocyanate because of its high reaction rate.

The content of the (B) isocyanate-based cross-linking agent in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (A) copolymer. It is more preferably 1 part by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. If the content of the cross-linking agent is too small, the cohesive force will be insufficient, and if the content of the cross-linking agent is too large, the cross-linking density will be too high and the adhesive strength will decrease, which is not preferable.

In the pressure-sensitive adhesive composition, the molar ratio of the isocyanate groups of the (B) isocyanate-based cross-linking agent to the reactive functional groups of the (A) copolymer (molar amount of isocyanate groups/molar amount of reactive functional groups) is , is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.1 or more, preferably 10 or less, more preferably 5 or less, still more preferably 2 or less.

((C) metal chelate compound)
The pressure-sensitive adhesive composition contains (C) a metal chelate compound. This makes it possible to shorten the curing time in the formation of the pressure-sensitive adhesive composition, and to suppress heavy peeling of the obtained pressure-sensitive adhesive film. The (C) metal chelate compound is a complex in which a ligand having two or more coordinating atoms forms a ring and is bound to a central metal. The (C) metal chelate compound may be used alone, or two or more of them may be used in combination.

The metal constituting the (C) metal chelate compound is, for example, one selected from aluminum, zirconium, titanium, zinc, barium, calcium, copper, strontium, chromium, cobalt, iron, indium, magnesium, manganese and nickel. Alternatively, two or more kinds of metal atoms are included. Among these, at least one metal atom selected from aluminum, zirconium, titanium and zinc is suitable. The metal chelate compound (C) preferably does not contain tin as a constituent metal.

In (C) the metal chelate compound, the coordination number can be selected within an appropriate range in consideration of the type of metal atom used and the intended effect, and is not particularly limited. In (C) the metal chelate compound, the coordination number of the metal atom can be 3-20, preferably 4-16. In the present invention, "coordination number" refers to the number of coordination bonds formed between the metal atom and the ligand.

Examples of the ligand (chelating agent) constituting the (C) metal chelate compound include polyaminocarboxylic acids, oxycarboxylic acids, condensed phosphates, and the like. The (C) metal chelate compound preferably contains a ligand represented by the following formula (3).

［式中、Ｒ¹¹およびＲ¹²は、それぞれ独立に、水素、アルキル基またはアルコキシ基を示す。］

[In the formula, R ¹¹ and R ¹² each independently represent hydrogen, an alkyl group or an alkoxy group. ]

The alkyl group represented by R ¹¹ or R ¹² is preferably an alkyl group having 1 to 8 carbon atoms. Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group and heptyl. linear or branched alkyl groups such as octyl groups, cyclic alkyl groups such as cyclohexyl groups, and the like. A linear or branched alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

The alkoxy group represented by R ¹¹ or R ¹² is preferably a group in which an alkyl group having 1 to 8 carbon atoms is bonded to an oxygen atom, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, group, sec-butoxy group, tet-butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.

Examples of ligands contained in the (C) metal chelate compound include acetylacetonate-based ligands, acetoacetate-based ligands, acetonate-based ligands, lactate-based ligands, and carboxylic acid-based ligands. ligands, citrate-based ligands, glycol-based ligands, and the like. Specific examples include acetylacetonate, alkylacetoacetate, alkylenediaminetetraacetate, diisoalkoxybisalkylacetoacetate, diisopropoxybisalkylacetoacetate, di-n-alkoxy-bisalkyl-acetoacetate, hydroxyalkylene and diamine triacetate.

Specific examples of the metal chelate compound (C) include zirconium tetraacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), zirconium dibutoxybis(ethylacetoacetate), and the like. zirconium chelate compounds of; titanium chelate compounds such as titanium ethylacetoacetate, titanium diisopropoxybis(acetylacetonate), titanium tetraacetylacetonate, titanium diisopropoxybis(ethylacetoacetate); aluminum tris(acetylacetonate) , aluminum bisethylacetoacetate monoacetylacetonate, aluminum tris(ethylacetoacetate), aluminum ethylacetoacetate diisopropylate, aluminum alkylacetoacetate diisopropylate; zinc chelates such as hydrates; barium chelates such as bis(acetylacetonate)diaquabarium(II); calcium chelates such as bis(acetylacetonate)diaquacalcium(II); copper(II)bis copper chelates such as acetylacetonate; strontium chelates such as bis(acetylacetonate)diaquastrontium(II); chromium chelates such as chromium tris(acetylacetonate); cobalt(III) tris(acetylacetonate); Cobalt chelate compounds such as bis(acetylacetonate) diaquacobalt(II); iron chelate compounds such as iron(III) tris(acetylacetonate), bis(acetylacetonate) diaqua iron(II); indium tris(acetyl acetonate); magnesium chelate compounds such as bis(acetylacetonate)diaquamagnesium(II); manganese chelate compounds such as bis(acetylacetonate)diaquamanganese(II); nickel(II)bis Examples include nickel chelate compounds such as acetylacetonate dihydrate. Among these, zirconium chelate compounds and titanium chelate compounds are preferred.

The content of (C) the metal chelate compound in the adhesive composition of the present invention is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass, relative to 100 parts by mass of the copolymer (A). Above, more preferably 0.04 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, still more preferably 0.3 parts by mass or less. By setting the content of the metal chelate compound (C) within the above range, it is possible to obtain an excellent effect of promoting crosslinking and an effect of suppressing heavy peeling.

Here, if the pressure-sensitive adhesive composition contains a metal compound derived from the chain transfer agent used in the living radical polymerization, it is believed that the metal compound acts on the adherend to easily cause heavy release. In the pressure-sensitive adhesive composition of the present invention, it is possible to suppress heavy peeling by containing the metal chelate compound (C). The metal compound derived from the chain transfer agent differs depending on the living radical polymerization method, and examples thereof include tellurium compounds in the case of the TERP method, and copper compounds, ruthenium compounds, nickel compounds, and iron compounds in the case of the ATRP method.

When the (A) copolymer contains a metal compound derived from a chain transfer agent, the content of the (C) metal chelate compound in the pressure-sensitive adhesive composition is the chain contained in the (A) copolymer It is preferably 2 parts by mass or more, more preferably 2.5 parts by mass or more, still more preferably 4 parts by mass or more, and preferably 40 parts by mass or less relative to 1 part by mass of the metal compound derived from the transfer agent in terms of metal. , more preferably 35 parts by mass or less, and still more preferably 30 parts by mass or less. By adjusting the mass ratio of the metal compound derived from the chain transfer agent and the (C) metal chelate compound, heavy exfoliation can be suppressed.

By blending (C) the metal chelate compound in the adhesive composition of the present invention, the reaction between the (A) reactive functional group of the copolymer and (B) the isocyanate cross-linking agent can be promoted. Therefore, the pressure-sensitive adhesive composition of the present invention can shorten the curing period for forming an adhesive layer without blending an organic tin compound. Therefore, the content of the organotin compound in the pressure-sensitive adhesive composition of the present invention is 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less. In addition, it is preferable that the pressure-sensitive adhesive composition of the present invention does not contain an organic tin compound. The organic tin compound is used as a cross-linking accelerator, and includes dibutyltin laurate, dibutyltin dioctylate, and the like.

(Other additives)
In addition to (A) the copolymer, (B) the isocyanate-based cross-linking agent, and (C) the metal chelate compound, the pressure-sensitive adhesive composition of the present invention may contain other additives. Other additives include, for example, the following.

(D) A cross-linking retarder may be added to the pressure-sensitive adhesive composition, if necessary. The (D) cross-linking retarder blocks the isocyanate group of the cross-linking agent in the pressure-sensitive adhesive composition containing the isocyanate-based cross-linking agent, thereby suppressing excessive viscosity increase of the pressure-sensitive adhesive composition. is a compound. (D) The type of cross-linking retarder is not particularly limited, but for example, β- diketones; β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; benzoylacetone and the like can be used. . As the cross-linking retarder (D), those capable of acting as a chelating agent are preferable, and β-diketones and β-ketoesters are preferable.

The content of the (D) cross-linking retarder that can be blended in the pressure-sensitive adhesive composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the (A) copolymer. It is preferably 3 parts by mass or more, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less. By adjusting the content of the (D) cross-linking retarder to the above range, after blending the (B) isocyanate-based cross-linking agent into the pressure-sensitive adhesive composition, excessive viscosity increase and gelation of the pressure-sensitive adhesive composition can be prevented. can be suppressed and the storage stability (pot life) of the pressure-sensitive adhesive composition can be extended.

Further, when a compound acting as a chelating agent is used as the (D) cross-linking retarder, (A) the metal component of the metal compound derived from the chain transfer agent contained in the copolymer and (C) the metal chelate compound The mass ratio of the sum of (C) the chelating agent (ligand) component in the metal chelate and (D) the cross-linking retarder (chelate component/metal component) with respect to the sum of the metal components is preferably 100 or more, and more It is preferably 150 or more, more preferably 200 or more, preferably 1000 or less, more preferably 900 or less.

The pressure-sensitive adhesive composition of the present invention can be used by blending a silane coupling agent, if necessary. Examples of the silane coupling agent include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, Epoxy group-containing silane coupling agents such as 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3- Amino group-containing silane coupling agents such as triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3- (meth)acrylic group-containing silane coupling agents such as methacryloxypropyltriethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane; and the like.

The content of the silane coupling agent that can be blended in the adhesive composition is preferably 1 part by mass or less, more preferably 0.01 part by mass to 100 parts by mass of the copolymer (A). 1 part by mass, more preferably 0.02 to 0.6 parts by mass. By adjusting the content of the silane coupling agent within the above range, water resistance at the interface can be improved when the pressure-sensitive adhesive layer is applied to a hydrophilic adherend such as glass.

If necessary, the pressure-sensitive adhesive composition of the present invention may contain (B) a cross-linking agent other than the isocyanate-based cross-linking agent. Examples of the (B) cross-linking agent other than the isocyanate-based cross-linking agent include epoxy-based cross-linking agents. An epoxy-based cross-linking agent refers to a polyfunctional epoxy compound having two or more epoxy groups in one molecule. Epoxy cross-linking agents include, for example, bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, diamineglycidylamine, 1 ,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether , polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether , adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether and the like.

The content of the epoxy-based cross-linking agent that can be blended in the pressure-sensitive adhesive composition is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the copolymer (A), and 0.01 part by mass. It is more preferably from 0.02 to 3 parts by mass, more preferably from 0.02 to 3 parts by mass. Cohesive force and heat resistance can be further improved by adjusting the content of the epoxy-based cross-linking agent within the above range.

The pressure-sensitive adhesive composition of the present invention may optionally contain a tackifying resin other than (A) the copolymer. Examples of the tackifying resin include rosin resins such as rosin ester resins, terpene resins such as terpene phenol resins, and petroleum resins. Among them, rosin ester resins and terpene phenol resins are preferred.

The rosin ester-based resin is a rosin resin containing abietic acid as a main component, a disproportionated rosin resin, a hydrogenated rosin resin, a dimer of a resin acid such as abietic acid (polymerized rosin resin), etc., which is esterified with an alcohol. It is a resin obtained by curing. A part of the hydroxyl groups of the alcohol used for the esterification are not used for the esterification and are contained in the resin, so that the hydroxyl value is adjusted. Alcohols include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol. A resin obtained by esterifying a rosin resin is a rosin ester resin, a resin obtained by esterifying a disproportionated rosin resin is a disproportionated rosin ester resin, a resin obtained by esterifying a hydrogenated rosin resin is a hydrogenated rosin ester resin, and a polymerized rosin. Polymerized rosin ester resin is obtained by esterifying resin. The terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol.

The content of the tackifying resin that can be blended in the adhesive composition is preferably 5 parts by mass to 40 parts by mass with respect to 100 parts by mass of the copolymer (A). By adjusting the content of the tackifying resin within the above range, the constant load releasability of the adhesive film from the adherend can be improved.

The pressure-sensitive adhesive composition of the present invention may optionally contain dyes, pigments, dyes, fluorescent brighteners, wetting agents, surface tension modifiers, thickeners, antifungal agents, preservatives, oxygen absorbers, ultraviolet rays. Absorbers, near-infrared absorbers, water-soluble quenchers, antioxidants, fragrances, metal deactivators, nucleating agents, antistatic agents, alkylating agents, flame retardants, lubricants, processing aids, etc. These are appropriately selected and blended for use according to the application and purpose of use of the adhesive.

(Method for producing pressure-sensitive adhesive composition)
The pressure-sensitive adhesive composition can be produced by mixing the (A) copolymer, (B) an isocyanate-based cross-linking agent, (C) a metal chelate compound, and optionally other additives. . The pressure-sensitive adhesive composition contains (A) a solvent derived from the production of the copolymer, or is further diluted with a suitable solvent to have a viscosity suitable for forming the pressure-sensitive adhesive layer. It may be a liquid solution.

Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone. esters such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; glycol ether solvents such as propylene glycol monomethyl ether; These solvents may be used singly or in combination of two or more.

The amount of the solvent used may be appropriately adjusted so that the pressure-sensitive adhesive composition has a viscosity suitable for coating, and is not particularly limited. It is preferable to use it so that it will be from mass % to 95 mass %.

(Use of adhesive composition)
The application of the pressure-sensitive adhesive composition is not particularly limited, and it can be used for a wide range of applications, but it is particularly preferably used for optical applications such as the production of optical products and optical members.

The optical product means that the product has optical properties (e.g., polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.) Refers to the product used. Examples of the optical product include display devices such as a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper, an input device such as a touch panel, or a combination of these display devices and an input device. and a device obtained by appropriately combining the above.

The optical member means a member having the optical properties. The optical member includes, for example, a member constituting equipment (optical equipment) such as the display device (image display device) and the input device, or a member used in these equipment. Examples of optical members include polarizing plates, wave plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, transparent conductive films (ITO films), design films, decorative films, surfaces Protective plates, prisms, lenses, color filters, transparent substrates, and members in which these are laminated (these are sometimes collectively referred to as "optical films"), and the like. The above-mentioned "plate" and "film" include forms such as plate-like, film-like, and sheet-like, respectively. For example, "polarizing film" includes "polarizing plate" and "polarizing sheet". As described above, the "optical member" in the present invention includes a member (design film, decorative film, and surface protection film) are also included.

A material constituting the optical member is not particularly limited, but examples thereof include glass, acrylic resin, polycarbonate, polyethylene terephthalate, metal (including metal oxide), and the like.

<2. Adhesive film>
The pressure-sensitive adhesive film of the present invention has a base film and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive layer is formed on at least one side or at least a portion of the base film. In addition, in this invention, a tape and a sheet shall also be included in a "film."

The thickness of the base film is not particularly limited and may be appropriately selected, but it is generally preferably 10 μm or more, more preferably 20 μm or more, and preferably 250 μm or less, more preferably 200 μm or less.

The substrate film can be appropriately selected and used according to the application of the adhesive film. For example, when the adhesive film is used for optical purposes, it is preferably a transparent substrate film. A transparent substrate refers to a substrate that is transparent. Examples of transparent substrate films include polyester resins such as polyethylene terephthalate (PET); acrylic resins such as polymethyl methacrylate (PMMA); polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, and polyvinyl chloride. , polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer. The plastic materials may be used alone or in combination of two or more. Among these, PET is preferable in terms of excellent mechanical strength and dimensional stability. In addition, TAC is preferable because the in-plane retardation of the film is very small. That is, as the transparent substrate film, a PET film (especially a biaxially stretched PET film) and a TAC film are preferable.

Although the total light transmittance (JIS K7361-1 (1997)) of the transparent base film in the visible light wavelength region is not particularly limited, it is preferably 85% or more. When the total light transmittance is 85% or more, the transparency is excellent, so that the visibility and display quality of the display portion of the optical product and the appearance of the optical product are less likely to be adversely affected.

For the purpose of improving adhesion to the layer provided on the surface of the base film, one or both sides of the base film can be subjected to surface treatment by an oxidation method, a roughening method, or the like, if desired. Examples of the oxidation method include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone/ultraviolet irradiation treatment, and the like. Examples of the roughening method include a sandblasting method and a solvent treatment method. These surface treatment methods are appropriately selected according to the type of substrate film, but generally corona discharge treatment is preferably used from the standpoints of effectiveness and operability. Further, as the base film, one surface or both surfaces of which is subjected to a primer treatment can be used.

The thickness of the pressure-sensitive adhesive layer may be appropriately adjusted according to the use of the pressure-sensitive adhesive film. For example, it is preferably 0.1 μm to 20 μm for protective film applications (slight adhesion), and 10 μm to 350 μm for OCA applications (strong adhesion).

The gel fraction of the adhesive layer is preferably 30% to 100%, more preferably 40% to 100%, and 50% to 100% from the viewpoint of durability and adhesive strength. More preferably, it is particularly preferably 80% to 100%. If the gel fraction is too low, durability is likely to be insufficient due to insufficient cohesive force, and adhesive residue tends to occur when peeled off. The gel fraction can be controlled by the blending amount of the cross-linking agent in the pressure-sensitive adhesive composition, the cross-linking treatment temperature, and the cross-linking treatment time.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and includes, for example, the following methods (1) and (2).
(1) A method of applying an adhesive composition to one or both sides of a substrate film using various coating devices, removing the solvent by drying, and curing as necessary.
(2) Using various coating devices, the adhesive composition is applied to the release surface of the release film whose surface has been subjected to release treatment, the solvent is removed by drying, and if necessary, after curing, the substrate A method of transferring onto one or both sides of a film.

Examples of the coating apparatus include reverse roll coaters, gravure coaters, forward roll coaters, knife coaters, wire bar coaters, doctor blade coaters, slot die coaters, curtain coaters, and dip coaters.

The drying temperature for removing the solvent by drying is preferably 40°C to 200°C, more preferably 60°C to 180°C. The drying time is preferably 5 seconds to 20 minutes, more preferably 10 seconds to 10 minutes. Drying means include hot air, near-infrared rays, infrared rays, and high frequencies. Further, the curing conditions include, for example, 23° C. for about 3 to 7 days.

The pressure-sensitive adhesive film may have a release film (separator) on the surface of the pressure-sensitive adhesive layer until it is used. A release layer is provided on the opposite side of the adhesive layer laminated surface of the base film without using a separate release film, and the surface of the release layer is wound in a roll so that the exposed side of the adhesive layer is in contact. It may be turned or laminated in a stack. The release film is used as a protective material for the pressure-sensitive adhesive layer, and is peeled off when the pressure-sensitive adhesive film of the present invention is attached to an adherend.

Examples of the release film include paper such as glassine paper, coated paper, laminated paper, and various plastic films coated with a release agent such as silicone resin. As the plastic film to be used for the release film, the one exemplified as the base film can be appropriately used. Although the thickness of the release film is not particularly limited, it is usually 10 μm to 150 μm.

The pressure-sensitive adhesive film of the present invention may be a functional pressure-sensitive adhesive film having a pressure-sensitive adhesive layer on one side of a base film and a functional layer on the other side. Examples of the functional layer include coating layers having functions such as scratch resistance, antireflection, antiglare (antiglare), antifouling, antifingerprint, chemical resistance, and anti-glass scattering properties. A known method can be adopted as a method for forming the functional layer. Further, the functional layer may be a laminate of layers for exhibiting functions such as anti-glare properties, antifouling properties, anti-fingerprint properties, and chemical resistance. For example, by forming the hard coat layer into a laminated structure of a layer having excellent scratch resistance and a layer having excellent anti-glare properties, it is possible to obtain a hard coat layer having excellent properties of both scratch resistance and anti-glare properties.

<3. Image display device>
An image display device of the present invention is characterized by comprising the adhesive film. Examples of the image display device include a liquid crystal display, an organic EL (electroluminescence) display, a plasma display, and electronic paper.

Examples of the adhesive film include optical films, and specific examples include polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, transparent conductive films (ITO films), design films, decorative films, surface protective plates, and the like.

An image display device having the adhesive film of the present invention can be obtained by manufacturing the display device using the optical member having the adhesive film of the present invention or the adhesive film of the present invention.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is by no means limited to the following examples, and can be modified as appropriate without changing the gist of the invention. In addition, the polymerization rate of the copolymer, the weight average molecular weight (Mw), the molecular weight distribution (PDI), the solid content, the viscosity, the adhesive strength of the adhesive composition, the adhesive strength after heating, the adhesive residue, the peel strength to the release film, The gel fraction was evaluated according to the method described below.

Abbreviations have the following meanings.
BTEE: ethyl-2-methyl-2-n-butylteranyl-propionate V-70: 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)
MA: methyl acrylate BA: butyl acrylate 2-EHA: 2-ethylhexyl acrylate LA: lauryl acrylate CHA: cyclohexyl acrylate 4-HBA: 4-hydroxybutyl acrylate HEA: hydroxyethyl acrylate AcOEt: ethyl acetate

(Polymerization rate)
¹ H-NMR was measured (solvent: CDCl ₃ , internal standard: trimethylsilane (TMS)) using a nuclear magnetic resonance (NMR) spectrometer (manufactured by Bruker Biospin, model: AVANCE500 (frequency: 500 MHz)). . With respect to the obtained NMR spectrum, the integration ratio of the peaks of the monomer-derived vinyl group and the polymer-derived ester side chain peak was determined to calculate the polymerization rate of the monomer.

(Weight average molecular weight (Mw) and molecular weight distribution (PDI))
It was determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (Model HLC-8320GPC manufactured by Tosoh Corporation). Two columns of TSKgel Super Multipore HZ-H (manufactured by Tosoh Corporation) were used, a tetrahydrofuran solution was used as a mobile phase, and a differential refractometer was used as a detector. The measurement conditions were a column temperature of 40° C., a sample concentration of 10 mg/mL, a sample injection volume of 10 μm, and a flow rate of 0.2 mL/min. Polystyrene (molecular weight 2,890,000, 1,090,000, 775,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630, 440) was used as a standard. Then, a calibration curve (calibration curve) was prepared, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. A molecular weight distribution (PDI=Mw/Mn) was calculated from this measured value.

(solid content)
A copolymer solution having a weight of W1 (about 1.0 g) was weighed into an aluminum cup (weight of W0) and dried under reduced pressure at 130° C. for 1 hour. The mass (W2) of the aluminum cup containing the dried copolymer was measured, and the solid content was calculated from the following formula.
Solid content (mass%) = [(W2-W0) / W1] × 100

(viscosity)
Using a Brookfield viscometer (trade name: TVB-15, manufactured by Toki Sangyo Co., Ltd.), the viscosity was measured using an M3 rotor at 25° C. and a rotor speed of 60 rpm.

<Production of copolymer>
(Synthesis example 1)
2-EHA (475.0 g), 4-HBA (25.0 g), V-70 (45.7 mg) and AcOEt (377.2 g) were charged into a flask equipped with an argon gas inlet tube and a stirrer, and argon was added. After substitution, BTEE (111.1 mg) was added and reacted at 33° C. for 20 hours to polymerize. The polymerization rate was 88.5%.

After completion of the reaction, AcOEt was added to the reaction solution to obtain a copolymer A solution. The obtained copolymer A had an Mw of 974,000, a PDI of 2.34, and a Tg of -69°C. was 0.03 mol. The copolymer solution had a solid content of 22.3 mass % and a viscosity of 3,881 mPa·s. The content of each structural unit and the amount of reactive functional groups in the copolymer were calculated from the charging ratio of the vinyl monomers used in the polymerization reaction.

After drying the solution of copolymer A, it was subjected to ashing treatment, and by inductively coupled plasma mass spectrometry (ICP/MS), it was confirmed that the amount of tellurium compound relative to the solid content of the solution of copolymer A was 106 ppm in terms of metal. confirmed.

(Synthesis example 2)
BA (475 g), 4-HBA (25 g), V-70 (61.7 mg) and AcOEt (377.2 g) were charged into a flask equipped with an argon gas inlet tube and a stirrer, and after purging with argon, BTEE (200 .9 mg) was added and reacted at 33° C. for 30 hours to polymerize. The polymerization rate was 86.2%.

After completion of the reaction, AcOEt was added to the reaction solution to obtain a copolymer B solution. The resulting copolymer B had an Mw of 701,000, a PDI of 1.63, and a Tg of -53°C. was 0.03 mol. The copolymer solution had a solid content of 19.8% by mass and a viscosity of 2,364 mPa·s. The content of each structural unit and the amount of reactive functional groups in the copolymer were calculated from the charging ratio of the vinyl monomers used in the polymerization reaction.

After drying the solution of copolymer B, it was subjected to ashing treatment, and by inductively coupled plasma mass spectrometry (ICP/MS), it was confirmed that the amount of tellurium compound relative to the solid content of the solution of copolymer B was 197 ppm in terms of metal. confirmed.

(Synthesis Example 3)
BA (300 g), 2-EHA (75 g), CHA (100 g), HEA (25 g), V-70 (38.8 mg), AcOEt (377.2 g) were placed in a flask equipped with an argon gas inlet tube and a stirrer. was charged, and after purging with argon, BTEE (111.0 mg) was added and reacted at 33° C. for 22 hours to polymerize. The polymerization rate was 81.1%.

After completion of the reaction, AcOEt was added to the reaction solution to obtain a copolymer C solution. The resulting copolymer C had an Mw of 941,000, a PDI of 1.95, and a Tg of -44°C. The amount of functional groups was 0.04 mol. The copolymer solution had a solid content of 17.6 mass % and a viscosity of 4368 mPa·s. The content of each structural unit and the amount of reactive functional groups in the copolymer were calculated from the charging ratio of the vinyl monomers used in the polymerization reaction.

After drying the solution of copolymer C, it was subjected to ashing treatment, and by inductively coupled plasma mass spectrometry (ICP/MS), it was confirmed that the amount of tellurium compound relative to the solid content of the solution of copolymer C was 128 ppm in terms of metal. confirmed.

(Synthesis Example 4)
MA (50 g), 2-EHA (350 g), LA (75 g), 4-HBA (25 g), V-70 (57.1 mg), AcOEt (333.1 mg) were added to a flask equipped with an argon gas inlet tube and a stirrer. 3 g) was charged, and after purging with argon, BTEE (299.87 mg) was added and reacted at 33° C. for 21 hours to polymerize. The polymerization rate was 89.4%.

After completion of the reaction, AcOEt was added to the reaction solution to obtain a copolymer C solution. The resulting copolymer D had an Mw of 478,000, a PDI of 1.78, and a Tg of -56°C. was 0.03 mol. The copolymer solution had a solid content of 42.4 mass % and a viscosity of 7070 mPa·s. The content of each structural unit and the amount of reactive functional groups in the copolymer were calculated from the charging ratio of the vinyl monomers used in the polymerization reaction.

After drying the solution of copolymer D, it was subjected to ashing treatment, and by inductively coupled plasma mass spectrometry (ICP/MS), it was confirmed that the amount of tellurium compound relative to the solid content of the solution of copolymer D was 285 ppm in terms of metal. confirmed.

<Production of adhesive composition>
(Adhesive composition No. 1)
With respect to 448.4 parts by mass of the solution of the copolymer A obtained in Synthesis Example 1 (100 parts by mass of the copolymer component, 348.4 parts by mass of AcOEt), 6.31 parts by mass of the isocyanate compound and 0 parts of the zirconium chelate compound were added. .08 parts by mass, 13.9 parts by mass of acetylacetone, and 196.6 parts by mass of AcOEt were added and stirred to give PSA composition No. 1. got 1.

(Adhesive composition Nos. 2 to 28)
Except for changing the formulation as shown in Tables 2 to 4, pressure-sensitive adhesive composition No. Adhesive composition No. 1 was prepared in the same manner as in No. 1. 2-28 were made. The amount of solvent in Tables 2 to 4 is the total amount of AcOEt contained in the copolymer solution and AcOEt added during preparation of the pressure-sensitive adhesive composition.

<Production of adhesive film>
(Adhesive film No. 1)
Adhesive composition No. 1 was applied onto a polyethylene terephthalate (PET) film (thickness: 125 μm) so that the thickness after drying would be 7 μm. The PET film coated with the adhesive composition was dried at 100° C. for 1 minute, and adhesive film No. 1 having an adhesive layer was obtained. 1 was produced. A release film (thickness: 25 μm, manufactured by Toray Advanced Film Co., Ltd., “Therapeal (registered trademark) WZ”) was attached to the resulting pressure-sensitive adhesive layer, and cured by standing at 23° C. for 1 week.

(Adhesive film No. 2 to 5)
Adhesive composition No. 1, Adhesive composition No. Adhesive film No. 2 except for changing to 2 to 5. Adhesive film No. 1 was prepared in the same manner as in 1. 2 to 5 were produced.

(Adhesive film No. 6)
Adhesive composition No. 6 was applied onto a PET film (thickness: 125 μm) so that the thickness after drying would be 10 μm. The PET film coated with the adhesive composition was dried at 100° C. for 2 minutes to prepare an adhesive film having an adhesive layer. A release film (thickness: 25 μm, manufactured by Toray Advanced Film Co., Ltd., “Therapeal (registered trademark) WZ”) was attached to the resulting pressure-sensitive adhesive layer, and cured by standing at 23° C. for 1 week.

(Adhesive film No. 7 to 19)
Adhesive composition No. 6 was mixed with adhesive composition No. 6. Adhesive film No. 7 to 19 except that the adhesive film No. Adhesive film no. 7-19 were made.

(Adhesive film No. 20)
Adhesive composition No. 20 was applied onto a PET film (thickness: 50 μm) so that the thickness after drying would be 10 μm. The PET film coated with the adhesive composition was dried at 100° C. for 2 minutes to prepare an adhesive film having an adhesive layer. A release film (thickness: 25 μm, manufactured by Higashiyama Film Co., Ltd., “HY-PS11”) was attached to the resulting pressure-sensitive adhesive layer, and left at 40° C. for 3 days for curing.

(Adhesive film No. 21 to 28)
Adhesive composition No. 20, adhesive composition No. Adhesive film No. 21 to 28, except for the change. Adhesive film no. 21-28 were produced.

<Evaluation of adhesive film>
(IR peak intensity ratio)
Adhesive film no. With respect to the pressure-sensitive adhesive layers 1 to 5, the amount of residual isocyanate group was evaluated after curing for 3 hours and after 7 days (1 week). The amount of residual isocyanate groups was evaluated by measuring the peak intensity at 2275 cm ⁻¹ , which is the IR peak of reverse pair stretching of isocyanate groups. Measurement was performed by a total reflection method (ATR method) using a Fourier transform infrared spectrophotometer (FT-IR). Table 5 shows adhesive film Nos. The ratio of strength to peak strength after 3 hours of curing period of No. 5 is shown.

(Adhesive force)
The adhesive strength of the adhesive film was measured according to the method for measuring adhesive strength of JIS Z0237 (2009) (method 1: a test method in which a tape and a sheet are peeled off from a stainless test plate at 180°). Specifically, a surface-cleaned adherend (stainless steel plate (SUS304BA) Ra 50 nm (JIS B 0601 (1994))) is crimped using a crimping device (roller mass 2 kg), and the adherend is pressed. The adhesive strength was measured when the film was peeled off at 180°. The test temperature was 23° C., and the peeling speed was 300 mm/min. The adhesive film had a width of 25 mm and a length of 300 mm. After the start of the measurement, the first 25 mm length measurements were ignored, and then the adhesion measurements for 50 mm lengths peeled from the test panel were averaged.

(Adhesive strength after heating)
In the same manner as in the measurement of adhesive strength, the adhesive film was pressed onto the adherend, heated at 150° C. for 1 hour, and then cooled at room temperature (23° C.) for 1 hour. After cooling, the adhesive strength when peeled off at 180° was measured in the same manner as the measurement of the adhesive strength. Also, the rate of increase in adhesive strength due to heating was calculated by the following formula.
Increase rate (%) = (adhesive strength after heating/adhesive strength unheated) x 100

(Adhesive residue on adherend after adhesion measurement)
In the measurement of the adhesive strength after heating, the adherend after the adhesive film was peeled off was visually observed to confirm whether there was any adhesive residue on the adherend. Those with no adhesive residue were evaluated as "Good", and those with adhesive residue were evaluated as "Poor".

(Peel force)
The release force when the release film is peeled off is determined according to the JIS Z0237 (2009) release force measurement method (method 4: a test method in which the release liner is peeled off from the adhesive surface of the tape or sheet at 180°). It was measured. Specifically, the adhesive film was fixed to a stainless steel plate with a double-sided adhesive tape, and the release force was measured when the release film was peeled off at an angle of 180° to the adhesive film. The test temperature was 23° C., and the peeling speed was 300 mm/min. The width of the release film and the adhesive film was 25 mm, and the length was 300 mm. After starting the measurement, the measured value of the first 25 mm length was ignored, and then the peel force measured value of 50 mm length peeled from the adhesive film was averaged.

(Peel strength after heating)
Adhesive film no. For 1 to 5, the adhesive film with the release film attached was heated at 100° C. for 1 hour and then cooled at 23° C. for 1 hour. Adhesive film no. For Nos. 6 to 28, the adhesive film attached with the release film was heated at 150° C. for 1 hour and then cooled at 23° C. for 1 hour. After cooling, the peel strength when peeled off at 180° was measured in the same manner as the measurement of the peel strength. Also, the rate of increase in peel force due to heating was calculated by the following formula.
Increase rate (%) = (peeling force after heating/unheated peeling force) x 100

(Gel fraction)
The adhesive composition was applied to a release film and dried at 100° C. for 1 minute (Adhesive composition Nos. 1 to 5) or 100° C. for 2 minutes (Adhesive composition Nos. 6 to 28). After that, after standing at 23° C. for 1 week for curing, the pressure-sensitive adhesive layer formed on the release film was peeled off.
An adhesive layer with a weight of W1 (about 0.10 g) was weighed onto a stainless steel wire mesh (400 mesh) with a weight of W0 and immersed in ethyl acetate at 60° C. for 24 hours. Thereafter, the pressure-sensitive adhesive layer and the stainless steel wire mesh were removed from the ethyl acetate, dried at 23° C. for 24 hours, and further dried under reduced pressure at 130° C. for 1 hour. After drying, the weight W2 of the stainless wire mesh containing the dried pressure-sensitive adhesive layer was measured, and the gel fraction was calculated from the following formula.
Gel fraction (mass%) = [(W2-W0)/W1] × 100

イソシアネート化合物：旭化成社製、デュラネート（登録商標）ＴＰＡ－１００
ジルコニウムキレート化合物：マツモトファインケミカル社製、オルガチックス（登録商標）ＺＣ－１５０（ジルコニウムテトラアセチルアセトネート）
チタンキレート化合物：マツモトファインケミカル社製、オルガチックス（登録商標）ＴＣ－７５０（チタンジイソプロポキシビス（エチルアセトアセテート））
アルミニウムキレート化合物：川研ファインケミカル社製、アルミキレートＡ（アルミニウムトリス（アセチルアセトネート））
有機スズ化合物：日東化成社製、ネオスタン（登録商標）Ｕ８１０（ジオクチルスズ）
アミン化合物：東京化成社製、１，４－ジアザビシクロ［２．２．２］オクタン

Isocyanate compound: Asahi Kasei Co., Ltd., Duranate (registered trademark) TPA-100
Zirconium chelate compound: Orgatics (registered trademark) ZC-150 (zirconium tetraacetylacetonate) manufactured by Matsumoto Fine Chemical Co., Ltd.
Titanium chelate compound: Orgatics (registered trademark) TC-750 (titanium diisopropoxybis (ethyl acetoacetate)) manufactured by Matsumoto Fine Chemical Co., Ltd.
Aluminum chelate compound: Aluminum chelate A (aluminum tris (acetylacetonate)) manufactured by Kawaken Fine Chemicals
Organic tin compound: Neostan (registered trademark) U810 (dioctyltin) manufactured by Nitto Kasei Co., Ltd.
Amine compound: manufactured by Tokyo Kasei Co., Ltd., 1,4-diazabicyclo[2.2.2]octane

As shown in Table 5, when a zirconium chelate compound or a titanium chelate compound was used as a cross-linking accelerator (adhesive composition Nos. 1 and 2), the IR peak intensity ratio was small even after a curing period of 3 hours. Therefore, it can be seen that these chelate compounds have a cross-linking promoting ability like the organotin compound (Adhesive composition No. 3). When an amine compound is used as a cross-linking accelerator (adhesive composition No. 4), the IR peak intensity ratio is 1.0 with a curing period of 3 hours. In other words, it can be seen that the amine compound does not have cross-linking acceleration ability.

Further, as shown in Table 5, when an organic tin compound was used as a cross-linking accelerator (adhesive film No. 3), the release force was lower than when no cross-linking accelerator was used (adhesive film No. 5). The rate of increase due to heating is high. On the other hand, when a zirconium chelate compound or a titanium chelate compound is used as a cross-linking accelerator (adhesive film Nos. 1 and 2), the rate of increase in release force due to heating is low, and heavy release is suppressed. there is

Further, as shown in Tables 6 to 8, when a metal chelate compound (zirconium chelate compound, titanium chelate compound, aluminum chelate compound) was used as a crosslinking accelerator (adhesive film Nos. 6 to 13, 16, 17), The rate of increase in the adhesive force to the adherend due to heating is also lower than in the cases where no cross-linking accelerator is used (adhesive film Nos. 15 and 19). Furthermore, when the cross-linking accelerator is not used for the copolymer A (adhesive film No. 15), the adhesive strength after heating is significantly increased, contaminating the adherend. On the other hand, adhesive film No. With 6 to 14, the increase in adhesive strength due to heating was suppressed, and no contamination of the adherend occurred. In addition, adhesive film No. In No. 19, no contamination of the adherend was observed, although the adhesive strength after heating was greatly increased. This is probably because the copolymer B has a higher cohesive force than the copolymer A. Moreover, adhesive film No. 22, 25 and 28 are considered to be due to the difference in the curing conditions during the production of the adhesive film and the thickness of the base film.

The present invention includes the following embodiments.
(Embodiment 1)
(A) a (meth)acrylic copolymer having a reactive functional group, (B) an isocyanate crosslinking agent, and (C) a metal chelate compound, and the (A) (meth)acrylic copolymer A pressure-sensitive adhesive composition characterized by coalescence obtained by living radical polymerization, a weight average molecular weight of 200,000 to 2,000,000, and a molecular weight distribution (PDI) of less than 3.0.

(Embodiment 2)
The content of the (C) metal chelate compound is 2 parts by mass or more with respect to 1 part by mass of the metal compound derived from the chain transfer agent contained in the (A) (meth)acrylic copolymer. The adhesive composition according to certain embodiment 1.

(Embodiment 3)
The reactive functional group of the (A) (meth)acrylic copolymer is selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a phosphine group and an epoxy group. 3. The adhesive composition according to embodiment 1 or 2, which is at least one.

(Embodiment 4)
The (A) (meth)acrylic copolymer contains 0.1% to 20% by mass of a structural unit derived from a vinyl monomer having a reactive functional group in 100% by mass of the total copolymer. The adhesive composition according to any one of embodiments 1-3.

(Embodiment 5)
Any one of Embodiments 1 to 4, wherein the (A) (meth)acrylic copolymer contains 80% by mass or more of structural units derived from a (meth)acrylic monomer in 100% by mass of the total copolymer. 1. The pressure-sensitive adhesive composition according to item 1.

(Embodiment 6)
In any one of Embodiments 1 to 5, the content of the (B) isocyanate cross-linking agent is 0.01 parts by mass to 20 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer. The adhesive composition described.

(Embodiment 7)
The (C) metal chelate compound is at least one metal selected from the group consisting of aluminum, zirconium, titanium, zinc, barium, calcium, copper, strontium, chromium, cobalt, iron, indium, magnesium, manganese and nickel. 7. The pressure-sensitive adhesive composition of any one of embodiments 1-6 comprising atoms.

(Embodiment 8)
The pressure-sensitive adhesive composition according to any one of Embodiments 1 to 7, wherein the (C) metal chelate compound contains a ligand represented by the following formula (3).

［式中、Ｒ¹¹およびＲ¹²は、それぞれ独立に、水素、アルキル基またはアルコキシ基を示す。］

[In the formula, R ¹¹ and R ¹² each independently represent hydrogen, an alkyl group or an alkoxy group. ]

(Embodiment 9)
Any one of Embodiments 1 to 8, wherein the content of the (C) metal chelate compound is 0.01 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer. The pressure-sensitive adhesive composition according to .

(Embodiment 10)
The pressure-sensitive adhesive composition according to any one of Embodiments 1 to 9, further comprising (D) a cross-linking retarder.

(Embodiment 11)
The pressure-sensitive adhesive composition according to any one of Embodiments 1 to 10, which is for optical use.

(Embodiment 12)
A pressure-sensitive adhesive film comprising a substrate film and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of Embodiments 1 to 11.

(Embodiment 13)
An image display device comprising the pressure-sensitive adhesive film according to Embodiment 12.

Claims (13)

(A) a (meth)acrylic copolymer having a reactive functional group, (B) an isocyanate cross-linking agent, and (C) a metal chelate compound,
The (A) (meth)acrylic copolymer is obtained by living radical polymerization, has a weight average molecular weight of 200,000 to 2,000,000, and a molecular weight distribution (PDI) of less than 3.0 . ,
The content of the (C) metal chelate compound is 2 parts by mass to 40 parts by mass with respect to 1 part by mass of the metal compound derived from the chain transfer agent contained in the (A) (meth)acrylic copolymer. A pressure-sensitive adhesive composition characterized by being parts by mass . The content of the (C) metal chelate compound is 4 parts by mass to 30 parts by mass with respect to 1 part by mass of the metal compound derived from the chain transfer agent contained in the (A) (meth) acrylic copolymer. The pressure-sensitive adhesive composition according to claim 1, which is parts by mass . The reactive functional group of the (A) (meth)acrylic copolymer is selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a phosphine group and an epoxy group. 3. The pressure-sensitive adhesive composition according to claim 1, which is at least one. The (A) (meth)acrylic copolymer contains 0.1% to 20% by mass of a structural unit derived from a vinyl monomer having a reactive functional group in 100% by mass of the total copolymer. The pressure-sensitive adhesive composition according to any one of claims 1-3. Any one of claims 1 to 4, wherein the (A) (meth)acrylic copolymer contains 80% by mass or more of structural units derived from a (meth)acrylic monomer in 100% by mass of the entire copolymer. 1. The pressure-sensitive adhesive composition according to item 1. Any one of claims 1 to 5, wherein the content of the (B) isocyanate-based cross-linking agent is 0.01 to 20 parts by mass with respect to 100 parts by mass of the (A) (meth)acrylic copolymer. 1. The pressure-sensitive adhesive composition according to item 1. The (C) metal chelate compound is at least one metal selected from the group consisting of aluminum, zirconium, titanium, zinc, barium, calcium, copper, strontium, chromium, cobalt, iron, indium, magnesium, manganese and nickel. The pressure-sensitive adhesive composition according to any one of claims 1 to 6, comprising atoms. The pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein the (C) metal chelate compound contains a ligand represented by the following formula (3).

[In the formula, R ¹¹ and R ¹² each independently represent hydrogen, an alkyl group or an alkoxy group. ] Any one of claims 1 to 8, wherein the content of the (C) metal chelate compound is 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the (A) (meth)acrylic copolymer. or the pressure-sensitive adhesive composition according to claim 1. The pressure-sensitive adhesive composition according to any one of claims 1 to 9, further comprising (D) a cross-linking retarder. The pressure-sensitive adhesive composition according to any one of claims 1 to 10, which is for optical use. A pressure-sensitive adhesive film comprising a substrate film and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 11. An image display device comprising the adhesive film according to claim 12 .