CN113646401A - Adhesive composition, adhesive layer, and adhesive sheet - Google Patents

Adhesive composition, adhesive layer, and adhesive sheet Download PDF

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Publication number
CN113646401A
CN113646401A CN202080024968.1A CN202080024968A CN113646401A CN 113646401 A CN113646401 A CN 113646401A CN 202080024968 A CN202080024968 A CN 202080024968A CN 113646401 A CN113646401 A CN 113646401A
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meth
mass
monomer
adhesive composition
acrylate
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渡边显士
尾崎真由
冈本昌之
本田哲士
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Nitto Denko Corp
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/08—Macromolecular additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Adhesive Tapes (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

The present invention relates to an adhesive composition comprising a base polymer and at least one oligomer obtained by polymerizing a monomer composition containing at least a vinyl monomer having at least one pigment structure in a side chain.

Description

Adhesive composition, adhesive layer, and adhesive sheet
Technical Field
The invention relates to an adhesive composition, an adhesive layer and an adhesive sheet.
Background
Conventionally, a transparent adhesive tape is preferably used for the adhesive tape in order to facilitate grasping of a position in a working process, bonding, or the like. On the other hand, colored adhesive tapes have been used for the purpose of changing the design, improving the design and visibility, and the like.
Pigments and dyes are often used for coloring adhesive tapes. For example, patent document 1 discloses that in an adhesive composition containing an acrylic polymer, a phenol resin, an epoxy resin, and a colorant, and containing the colorant in an amount of 10 parts by weight or less based on 100 parts by weight of the acrylic polymer, a pigment or a dye is preferably used as the colorant.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication (Kokai) No. 2015-013946
Disclosure of Invention
Problems to be solved by the invention
However, when the adhesive tape is colored with a pigment or a dye, aggregates may be generated in the adhesive composition, and good dispersibility cannot be obtained unless a dispersant is used.
In addition, there are also the following problems: the coloring component bleeds out from the adhesive composition, and after the adhesive tape is peeled off, the coloring component remains on the adherend.
In addition, depending on the type of pigment or dye, the adhesive properties may be deteriorated. In addition, in order to improve the dispersibility of the pigment, a resin having a high acid value may be used, and in this case, there is another problem such as corrosion of a metal adherend such as iron, stainless steel, and ITO.
Accordingly, an object of the present invention is to provide a colored pressure-sensitive adhesive composition having good adhesive strength, good dispersibility without using a resin having a high acid value or a dispersant, and no bleeding of a coloring matter component.
Means for solving the problems
The inventors of the present application have made intensive studies to solve the above problems. As a result, they have found that the above problems can be solved by using an oligomer obtained from a vinyl monomer having at least one dye structure in a side chain, and have completed the present invention.
One embodiment of the present invention relates to an adhesive composition comprising a base polymer and at least one oligomer, wherein the oligomer is obtained by polymerizing a monomer composition containing at least a vinyl monomer having at least one pigment structure in a side chain.
In one embodiment of the present invention, the base polymer is preferably a (meth) acrylic polymer in the adhesive composition.
In one embodiment of the present invention, the oligomer is preferably a (meth) acrylic oligomer in the adhesive composition.
In one embodiment of the present invention, the (meth) acrylic oligomer may be a homopolymer of a (meth) acrylic monomer having at least one dye structure in a side chain thereof in the adhesive composition.
In one embodiment of the present invention, the (meth) acrylic oligomer may be a copolymer of a (meth) acrylic monomer having at least one dye structure in a side chain and an alkyl (meth) acrylate in the adhesive composition.
In one embodiment of the present invention, the oligomer preferably has a weight average molecular weight of 1,000 to 50,000 in the adhesive composition.
One embodiment of the present invention relates to an adhesive layer formed from the adhesive composition.
One embodiment of the present invention relates to a pressure-sensitive adhesive sheet including the pressure-sensitive adhesive layer.
In one embodiment of the present invention, the pressure-sensitive adhesive sheet may include the pressure-sensitive adhesive layer on a transparent film.
ADVANTAGEOUS EFFECTS OF INVENTION
According to one embodiment of the present invention, a colored pressure-sensitive adhesive composition having good adhesive strength, good dispersibility without using a resin having a high acid value or a dispersant, and no bleeding of a coloring matter component can be provided.
Drawings
Fig. 1 is an example of a schematic cross-sectional view of an adhesive layer according to an embodiment of the present invention.
Fig. 2 is an example of a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention.
Fig. 3 is an example of a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below.
In the present specification, "a to B" indicating a range means "a to B inclusive". In the present specification, "mass%" is considered synonymous with "weight%" and "part by mass" is considered synonymous with "part by weight".
[ adhesive composition ]
An adhesive composition according to an embodiment of the present invention is an adhesive composition including a base polymer and at least one oligomer obtained by polymerizing a monomer composition including at least a vinyl monomer having at least one dye structure in a side chain.
In the above adhesive composition, since an oligomer obtained by polymerizing a vinyl monomer having a dye structure in a side chain is used as the dye, the dispersibility is good and bleeding of the dye component does not occur even when a resin having a high acid value or a dispersant is not used.
The components contained in the adhesive composition will be described in detail below.
< basic Polymer >
In the pressure-sensitive adhesive composition according to one embodiment of the present invention, the base polymer constituting the pressure-sensitive adhesive composition is not particularly limited, and known polymers used in pressure-sensitive adhesives can be used.
Examples thereof include (meth) acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, and epoxy polymers. Among them, from the viewpoint that coloring by a coloring matter becomes remarkable, a (meth) acrylic polymer having high transparency is more preferable. The polymer may be used alone or in combination of two or more.
The (meth) acrylic polymer means an acrylic polymer and/or a methacrylic polymer, and (meth) in the present invention means the same.
Hereinafter, the description will be mainly given of the embodiment in which a (meth) acrylic polymer is contained as a base polymer in the pressure-sensitive adhesive composition according to one embodiment of the present invention, but the present invention is not limited to this embodiment.
An embodiment of the present invention relates to an adhesive composition that may include a (meth) acrylic polymer as a base polymer. Typically, the pressure-sensitive adhesive composition may be a (meth) acrylic pressure-sensitive adhesive composition containing a (meth) acrylic polymer as a main component. The (meth) acrylic pressure-sensitive adhesive composition has excellent transparency.
The pressure-sensitive adhesive composition according to one embodiment of the present invention preferably contains, as a base polymer, for example, a (meth) acrylic polymer composed of a monomer component containing, at a ratio of 40 mass% or more, an alkyl (meth) acrylate having a linear or branched alkyl group having 1 to 20 carbon atoms at an ester end. Hereinafter, an alkyl (meth) acrylate having an alkyl group having not less than X and not more than Y carbon atoms at the ester end may be referred to as "(meth) acrylic acid CX-YAlkyl ester ".
In one embodiment, the (meth) acrylic acid C is contained in the whole monomer component of the (meth) acrylic polymer in view of easy availability of the balance of properties1-20The proportion of the alkyl ester is preferably more than 50% by mass, and may be, for example, 55% by mass or more, 60% by mass or more, and 70% by mass or more.
For the same reason, among the monomer components, (meth) acrylic acid C1-20The proportion of the alkyl ester may be, for example, 99.9% by mass or less, may be 99.5% by mass or less, and may be 99% by mass or less.
(meth) acrylic acid C in the (meth) acrylic polymer according to another embodiment1-20The proportion of the alkyl ester in the entire monomer component may be, for example, 98 mass% or less, and from the viewpoint of improving the cohesive property of the pressure-sensitive adhesive layer, 95 mass% or less, 85 mass% or less (for example, less than 80 mass%), 70 mass% or less, and 60 mass% or less.
As (meth) acrylic acid C1-20Non-limiting specific examples of the alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate.
Of these, it is preferable to use at least (meth) acrylic acid C4-20Alkyl esters, more preferably at least (meth) acrylic acid C4-18An alkyl ester. For example, a (meth) acrylic adhesive containing one or both of n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2EHA) as the monomer component is preferable, and at least BA is particularly preferable.
(meth) acrylic acid C which can be preferably used4-20Other examples of the alkyl ester include isononyl acrylate, n-Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), and isostearyl acrylate (iSTA).
In some embodiments, the monomer component constituting the (meth) acrylic polymer may contain (meth) acrylic acid C in a proportion of 40 mass% or more4-18An alkyl ester. (meth) acrylic acid C4-18The proportion of the alkyl ester in the monomer component may be, for example, 50 mass% or more, 60 mass% or more, and 65 mass% or more. (meth) acrylic acid C may be contained in a proportion of any lower limit or more than the above-mentioned one6-18A monomeric component of an alkyl ester.
In addition, from the viewpoint of improving the cohesive property of the pressure-sensitive adhesive layer, (meth) acrylic acid C4-18The proportion of the alkyl ester in the monomer component is usually preferably 99.5% by mass or less, and may be 95% by mass or less, may be 85% by mass or less, and may be 75% by mass or less. (meth) acrylic acid C may be contained in a proportion of not more than any of the above upper limits6-18A monomeric component of an alkyl ester.
The monomer component constituting the (meth) acrylic polymer may contain an alkyl (meth) acrylate and, if necessary, another monomer (copolymerizable monomer) copolymerizable with the alkyl (meth) acrylate.
As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, or the like) or a monomer having a high glass transition temperature (for example, 10 ℃ or higher) of a homopolymer can be preferably used.
The monomer having a polar group can contribute to introduction of a crosslinking point into the (meth) acrylic polymer or increase the cohesive force of the adhesive. The copolymerizable monomer may be used alone or in combination of two or more.
Specific non-limiting examples of the copolymerizable monomer include the following monomers.
Carboxyl group-containing monomer: for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, etc.
Acid anhydride group-containing monomer: for example, maleic anhydride, itaconic anhydride, and the like.
Hydroxyl group-containing monomer: examples of the (meth) acrylic acid include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.
Sulfonic acid group-or phosphoric acid group-containing monomer: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, and 2-hydroxyethylacryloyl phosphate.
Epoxy group-containing monomer: for example, epoxy group-containing acrylates such as glycidyl (meth) acrylate and 2-ethylglycidyl (meth) acrylate, allyl glycidyl ether, and glycidyl (meth) acrylate.
Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, and the like.
Isocyanate group-containing monomer: for example, 2-isocyanatoethyl (meth) acrylate and the like.
Amide group-containing monomer: for example, (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di (N-butyl) (meth) acrylamide, and N, N-di (tert-butyl) (meth) acrylamide; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, and N- (4-hydroxybutyl) (meth) acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine, and the like.
Amino group-containing monomers: such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate.
Monomer having epoxy group: such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.
Monomers having a ring containing a nitrogen atom: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinodione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, and N-vinylpyridazine (e.g., lactams such as N-vinyl-2-caprolactam), and the like.
Monomer having succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyhexamethylene succinimide.
Maleimide group: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.
Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide and the like.
Aminoalkyl (meth) acrylates: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate.
Alkoxy group-containing monomers: alkoxyalkyl (meth) acrylates (alkoxyalkyl (meth) acrylates) such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and ethoxypropyl (meth) acrylate; (meth) acrylic acid alkoxyalkylene glycols (for example, alkoxypolyalkylene glycol (meth) acrylates) such as (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolyethylene glycol, and (meth) acrylic acid methoxypolypropylene glycol.
Alkoxysilyl group-containing monomer: for example, alkoxysilyl group-containing (meth) acrylates such as 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane and 3- (meth) acryloyloxypropylmethyldiethoxysilane, and alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane.
Vinyl esters: for example, vinyl acetate, vinyl propionate, and the like.
Vinyl ethers: for example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compound: for example, styrene, α -methylstyrene, and vinyltoluene.
Olefins: for example, ethylene, butadiene, isoprene, isobutylene, and the like.
(meth) acrylate having alicyclic hydrocarbon group: for example, alicyclic hydrocarbon group-containing (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and adamantyl (meth) acrylate.
(meth) acrylate having an aromatic hydrocarbon group: for example, aromatic hydrocarbon group-containing (meth) acrylates such as phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.
And (meth) acrylates containing a heterocycle such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride-and fluorine atom-containing (meth) acrylates, silicon atom-containing (meth) acrylates such as silicone (meth) acrylates, and (meth) acrylates obtained from terpene compound derivative alcohols.
When such a copolymerizable monomer is used, the amount thereof is not particularly limited, and is usually preferably 0.01 mass% or more of the entire monomer component. From the viewpoint of more favorably exhibiting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer to be used may be 0.1 mass% or more, and may be 0.5 mass% or more of the entire monomer components.
In addition, the amount of the copolymerizable monomer used is usually suitably 50% by mass or less, preferably 40% by mass or less, of the entire monomer components, from the viewpoint of easily obtaining the balance of the adhesive properties.
In some embodiments, the monomer component constituting the (meth) acrylic polymer may include a monomer having a nitrogen atom. This can improve the cohesive force of the adhesive and satisfactorily improve the peeling force with time.
As a preferable example of the monomer having a nitrogen atom, a monomer having a ring containing a nitrogen atom is mentioned. As the monomer having a nitrogen atom-containing ring, the monomers exemplified above can be used, and examples thereof include N-vinyl cyclic amides represented by the following general formula (1).
[ chemical formula 1]
Figure BDA0003281778000000101
Here, in the general formula (1), R1Is a divalent organic group, specifically- (CH)2)n-. n is an integer of 2 to 7 (preferably 2,3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably used. Other preferable examples of the monomer having a nitrogen atom include (meth) acrylamide.
The amount of the monomer having a nitrogen atom (preferably, a monomer having a ring containing a nitrogen atom) to be used is not particularly limited, and may be, for example, 1 mass% or more, 3 mass% or more, 5 mass% or more, or 7 mass% or more of the entire monomer components.
In one embodiment, the amount of the monomer having a nitrogen atom to be used may be 10% by mass or more, 15% by mass or more, and 20% by mass or more of the entire monomer components.
The amount of the monomer having a nitrogen atom to be used is, for example, preferably 40% by mass or less, and may be 35% by mass or less, 30% by mass or less, and may be 25% by mass or less of the entire monomer component.
In another embodiment, the amount of the monomer having a nitrogen atom to be used may be, for example, 20 mass% or less and may be 15 mass% or less of the entire monomer component.
In some embodiments, the monomer component constituting the (meth) acrylic polymer may include a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the adhesive and the degree of crosslinking (for example, crosslinking based on an isocyanate crosslinking agent) can be appropriately adjusted.
The amount of the hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 0.01 mass% or more, 0.1 mass% or more, 0.5 mass% or more, 1 mass% or more, 5 mass% or more, or 10 mass% or more of the entire monomer components.
In some embodiments, the amount of the hydroxyl group-containing monomer used is, for example, preferably 40% by mass or less, and may be 30% by mass or less, 25% by mass or less, and may be 20% by mass or less, based on the total monomer components, from the viewpoint of suppressing the water absorption of the pressure-sensitive adhesive layer.
In another embodiment, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by mass or less, 10% by mass or less, or 5% by mass or less of the entire monomer components.
In the adhesive composition according to one embodiment of the present invention, the monomer component of the (meth) acrylic polymer may or may not include the alkoxyalkyl (meth) acrylate or the alkoxy polyalkylene glycol (meth) acrylate exemplified above.
In one embodiment of the technique according to the present embodiment, the ratio of the alkoxyalkyl (meth) acrylate in the monomer component of the (meth) acrylic polymer is less than 20% by mass, and the ratio of the alkoxy polyalkylene glycol (meth) acrylate is less than 20% by mass. This makes it easy to form the pressure-sensitive adhesive layer into a sheet without any problem such as gelation. By adopting the above monomer composition, the solid content concentration of the monomer mixture can be maintained in a predetermined range and the monomer mixture can be satisfactorily polymerized into a desired high molecular weight product (for example, having a weight average molecular weight (Mw) of more than 30 × 10)4Typically Mw is 40X 104Above).
The ratio of the alkoxyalkyl (meth) acrylate in the monomer component is preferably less than 10% by mass, more preferably less than 3% by mass, and still more preferably less than 1% by mass, and in a particularly preferred embodiment, the monomer component does not substantially contain the alkoxyalkyl (meth) acrylate (in an amount of 0 to 0.3% by mass).
Similarly, the content of the alkoxy polyalkylene glycol (meth) acrylate in the monomer component is preferably less than 10% by mass, more preferably less than 3% by mass, and still more preferably less than 1% by mass, and in a particularly preferred embodiment, the monomer component does not substantially contain the alkoxy polyalkylene glycol (meth) acrylate (content is 0 to 0.3% by mass).
In addition, from the viewpoint of suppressing gelation, the total ratio of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate in the monomer component of the (meth) acrylic polymer according to one preferred embodiment is limited to less than 20% by mass.
The total proportion of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is more preferably less than 10% by mass, still more preferably less than 3% by mass, and particularly preferably less than 1% by mass, and in one embodiment, the monomer component is substantially free of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate (in an amount of 0 to 0.3% by mass).
Similarly, the monomer component of the (meth) acrylic polymer according to the present embodiment may contain an alkoxy group-containing monomer in a proportion of less than 20% by mass or may not contain it. The amount of the alkoxy group-containing monomer in the monomer component is preferably less than 10% by mass, more preferably less than 3% by mass, and still more preferably less than 1% by mass, and in a particularly preferred embodiment, the monomer component does not substantially contain the alkoxy group-containing monomer (content is 0 to 0.3% by mass).
In some embodiments, the ratio of the carboxyl group-containing monomer in the monomer component of the (meth) acrylic polymer may be, for example, 2 mass% or less, 1 mass% or less, or 0.5 mass% or less (for example, less than 0.1 mass%). The monomer component of the (meth) acrylic polymer may be substantially free of a carboxyl group-containing monomer. The term "substantially free of carboxyl group-containing monomers" as used herein means that at least carboxyl group-containing monomers are not intentionally used.
The (meth) acrylic polymer having such a composition is likely to be a polymer having high water resistance reliability, and can be a polymer having metal corrosion resistance to an adherend containing metal.
In a preferred embodiment, the ratio of the hydrophilic monomer in the monomer component of the (meth) acrylic polymer is limited. Here, the "hydrophilic monomer" in the present specification means a carboxyl group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, a nitrogen atom-containing monomer (typically, an amide group-containing monomer such as (meth) acrylamide, and a nitrogen atom-containing ring-containing monomer such as N-vinyl-2-pyrrolidone), and an alkoxy group-containing monomer (typically, alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol (meth) acrylate).
In this embodiment, the proportion of the hydrophilic monomer in the monomer component of the (meth) acrylic polymer is preferably 32% by mass or less, and may be, for example, 30% by mass or less, and may be 28% by mass or less.
Although not particularly limited, the proportion of the hydrophilic monomer in the monomer component of the (meth) acrylic polymer may be 1% by mass or more, may be 10% by mass or more, and may be 20% by mass or more.
In some embodiments, the monomer component constituting the (meth) acrylic polymer may include a (meth) acrylate containing an alicyclic hydrocarbon group. This can increase the cohesive force of the adhesive and improve the peeling force with time.
As the alicyclic hydrocarbon group-containing (meth) acrylate, those exemplified above and the like can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably used. The amount of the alicyclic hydrocarbon group-containing (meth) acrylate used is not particularly limited, and may be, for example, 1 mass% or more, 3 mass% or more, or 5 mass% or more of the entire monomer components.
In one embodiment, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by mass or more and 15% by mass or more of the entire monomer components.
The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate to be used is preferably 40% by mass or less, and may be, for example, 30% by mass or less, and may be 25% by mass or less (for example, 15% by mass or less, and further 10% by mass or less).
The composition of the monomer component constituting the (meth) acrylic polymer can be set in the following manner: based on the composition of the monomer component, the glass transition temperature Tg determined by Fox equation is-75 ℃ or higher and 10 ℃ or lower.
In some embodiments, the Tg is suitably 0 ℃ or lower, preferably-10 ℃ or lower, and may be-20 ℃ or lower or-30 ℃ or lower, from the viewpoint of aggregation properties, impact resistance, and the like.
The Tg may be, for example, at-60 ℃ or higher, at-50 ℃ or higher, at-45 ℃ or higher or at-40 ℃ or higher.
The formula FOX here means, as shown below: tg of the copolymer, and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each monomer constituting the copolymer.
1/Tg＝Σ(Wi/Tgi)
In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction (copolymerization ratio on a weight basis) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i.
As the glass transition temperature of the homopolymer used for calculation of Tg, the value described in the known data was used. For example, the following values are used as the glass transition temperatures of homopolymers of the monomers mentioned below.
Figure BDA0003281778000000131
Figure BDA0003281778000000141
Regarding the glass transition temperature of a homopolymer of a monomer other than those exemplified in the above, the values described in "Polymer Handbook" (third edition, john wiley & Sons, inc.,1989) were used. In this document, it is described that when a plurality of values are used, the highest value is used.
As the monomer having a glass transition temperature which is not described in the above-mentioned Polymer Handbook, a value obtained by the following measurement method is used (see Japanese patent laid-open No. 2007-51271).
Specifically, 100 parts by mass of a monomer, 0.2 parts by mass of azobisisobutyronitrile and 200 parts by mass of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After removing oxygen from the polymerization system in this manner, the temperature was raised to 63 ℃ to carry out the reaction for 10 hours. Subsequently, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33 mass%. Subsequently, the homopolymer solution was cast on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test sample was punched out into a disk shape having a diameter of 7.9mm, sandwiched between parallel plates, and the viscoelasticity was measured at a temperature range of-70 to 150 ℃ in a shear mode at a temperature rise rate of 5 ℃/min while applying a shear strain at a frequency of 1Hz using a viscoelasticity tester (ARES, TA Instruments Co., Ltd.), and the peak top temperature of tan. delta. was taken as the Tg of the homopolymer.
The (meth) acrylic polymer according to the present embodiment is not particularly limited, and the SP value is preferably 23.0 (MJ/m)3)1/2The following. The SP value is more preferably 21.0 (MJ/m)3)1/2The following (e.g., 20.0 (MJ/m)3)1/2Below).
The lower limit of the SP value is not particularly limited, but is, for example, 10.0 (MJ/m)3)1/2Above, 15.0 (MJ/m)3)1/2The above is appropriate, and 18.0 (MJ/m) is preferable3)1/2The above.
It should be noted that the SP value of the (meth) acrylic polymer can be calculated by Fedors' method [ see "polymer process and technology (polymerng").&SCI.)”Vol.14, No. 2 (1974), pp.148-154]Namely the formula: SP value δ ═ (Σ Δ e/Σ Δ v)1/2To calculate.
(in the above formula,. DELTA.e is the evaporation energy (. DELTA.e) of each atom or atom group at 25 ℃ and. DELTA.v is the molar volume of each atom or atom group at the same temperature.)
The (meth) acrylic polymer having the above SP value can be obtained by: the monomer composition is appropriately determined based on the common technical knowledge of those skilled in the art.
The adhesive composition contains the monomer component having such a composition as described above in the form of a polymer, an unpolymerized product (i.e., a product in which the polymerizable functional group is not reacted), or a mixture thereof.
The adhesive composition may be in the following various forms: an aqueous dispersion type pressure-sensitive adhesive composition in which a pressure-sensitive adhesive (pressure-sensitive adhesive component) is dispersed in water; a solvent-based adhesive composition in which an organic solvent contains an adhesive; an active energy ray-curable adhesive composition prepared so as to form an adhesive by curing with an active energy ray such as ultraviolet ray or radioactive ray; and a hot melt adhesive composition which forms an adhesive when applied in a molten state by heating and cooled to a temperature near room temperature.
One preferred embodiment relates to an adhesive composition that is a solvent-based adhesive composition or a solventless adhesive composition. The solvent-free adhesive composition includes an active energy ray-curable adhesive composition and a hot-melt adhesive composition.
In the polymerization, a known or conventional thermal polymerization initiator or photopolymerization initiator can be used depending on the polymerization method, polymerization system, and the like. Such a polymerization initiator may be used singly or in appropriate combination of two or more.
The thermal polymerization initiator is not particularly limited. For example, azo polymerization initiators, peroxide initiators, redox initiators based on a combination of a peroxide and a reducing agent, substituted ethane initiators, and the like can be used.
More specifically, examples of the azo initiator include 2,2 ' -Azobisisobutyronitrile (AIBN), 2 ' -azobis (2-methylpropionamidine) disulfate, 2 ' -azobis (2-amidinopropane) dihydrochloride, 2 ' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2 ' -azobis (N, N ' -dimethyleneisobutyramidine), and 2,2 ' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; redox initiators such as combinations of persulfate and sodium bisulfite and combinations of peroxide and sodium ascorbate; and the like, but are not limited thereto. The thermal polymerization can be suitably carried out at a temperature of, for example, 20 to 100 ℃ and typically 40 to 80 ℃.
The photopolymerization initiator is not particularly limited. For example, ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α -ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzil photopolymerization initiators, benzophenone photopolymerization initiators, and thioxanthone photopolymerization initiators can be used.
The amount of the thermal polymerization initiator or the photopolymerization initiator used may be any amount that is generally used in accordance with the polymerization method, the polymerization system, or the like, and is not particularly limited. For example, the polymerization initiator may be used in an amount of 0.001 to 5 parts by mass (typically 0.01 to 2 parts by mass, for example, 0.01 to 1 part by mass) based on 100 parts by mass of the monomer to be polymerized.
In the above polymerization, various conventionally known chain transfer agents (which may be considered as a molecular weight regulator or a polymerization degree regulator) may be used as necessary.
As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α -thioglycerol can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used.
Specific examples of the non-sulfur chain transfer agent include: anilines such as N, N-dimethylaniline and N, N-diethylaniline; terpenes such as alpha-pinene and terpinolene; styrenes such as α -methylstyrene and α -methylstyrene dimer; compounds having benzylidene group such as dibenzylidene acetone, cinnamyl alcohol and cinnamyl aldehyde; hydroquinones such as hydroquinone and dihydroxynaphthalene; quinones such as benzoquinone and naphthoquinone; olefins such as 2, 3-dimethyl-2-butene and 1, 5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrides such as diphenylbenzene and triphenylbenzene; and so on.
The chain transfer agent may be used singly or in combination of two or more.
When a chain transfer agent is used, the amount of the chain transfer agent used may be, for example, 0.01 to 1 part by mass per 100 parts by mass of the monomer component. The technique according to this embodiment can be suitably carried out even in a mode in which a chain transfer agent is not used.
The molecular weight of the (meth) acrylic polymer obtained by appropriately using the above-mentioned various polymerization methods is not particularly limited, and may be set within an appropriate range according to the required performance. The weight average molecular weight (Mw) of the (meth) acrylic polymer is usually 10X 104Above (e.g., 20 × 10)4As described above), from the viewpoint of achieving both the cohesive force and the adhesive force with good balance, it exceeds 30 × 104Is suitable.
From the viewpoint of obtaining good adhesion reliability even in a high-temperature environment, the (meth) acrylic polymer according to one embodiment preferably has a molecular weight of 40 × 104Above (typically 50 × 10)4Above, for example, 55X 104Above) is used. According to a preferred embodiment of the technique according to this embodiment, since gelation can be suppressed by designing the monomer composition, a high molecular weight material in the above range can be obtained with high productivity by setting an appropriate solid content concentration.
The upper limit of Mw of the (meth) acrylic polymer may be usually 500X 104The following (for example, 150X 10)4Below). The Mw may be 75X 104The following.
Here, Mw means a value obtained by Gel Permeation Chromatography (GPC) in terms of standard polystyrene. The GPC apparatus may be, for example, a model name "HLC-8320 GPC" (column: TSKgel GMH-H (S), manufactured by Tosoh corporation). The same applies to the later-described embodiments. The Mw may be the Mw of the (meth) acrylic polymer in either the adhesive composition or the adhesive layer.
Some embodiments relate to an adhesive composition that may be an active energy ray-curable adhesive composition. Examples of the active energy ray include rays such as ultraviolet rays, visible rays, and infrared rays, radiation rays such as α rays, β rays, γ rays, electron rays, neutron rays, and X rays, and energy rays having energy capable of causing chemical reactions such as polymerization, crosslinking, and decomposition of an initiator.
A preferable example of the active energy ray-curable adhesive composition is a photocurable adhesive composition. The photocurable pressure-sensitive adhesive composition has the following advantages: even a thick adhesive layer can be easily formed. Among them, an ultraviolet-curable adhesive composition is preferable.
Typically, the photocurable pressure-sensitive adhesive composition contains at least a part (which may be a part of the monomer species or a part of the amount) of the monomer components of the composition in the form of a polymer.
The polymerization method for forming the polymer is not particularly limited, and various conventionally known polymerization methods can be suitably used. For example, it is possible to suitably employ: thermal polymerization (typically, carried out in the presence of a thermal polymerization initiator), such as solution polymerization, emulsion polymerization, or bulk polymerization; photopolymerization by irradiation with light such as ultraviolet light (typically, in the presence of a photopolymerization initiator); radiation polymerization by irradiation with radiation such as β rays and γ rays; and so on. Among them, photopolymerization is preferred.
One preferred embodiment relates to a photocurable adhesive composition containing a partial polymer of a monomer component. Such a partial polymer is typically a mixture of a polymer derived from a monomer component and an unreacted monomer, and preferably assumes a slurry state (viscous liquid state). Hereinafter, the partial polymer having such a property may be referred to as "monomer slurry" or simply "slurry".
The polymerization method for partially polymerizing the monomer component is not particularly limited, and various polymerization methods such as those described above can be appropriately selected and used. From the viewpoint of efficiency and simplicity, photopolymerization is preferably employed. According to photopolymerization, the polymerization conversion rate (monomer conversion) of the monomer component can be easily controlled by polymerization conditions such as the irradiation amount (light amount) of light.
The polymerization conversion rate of the monomer mixture in the partial polymer is not particularly limited. The polymerization conversion rate may be, for example, 70% by mass or less, preferably 60% by mass or less. From the viewpoint of ease of production, coatability, and the like of the adhesive composition containing the partial polymer, the polymerization conversion rate is usually suitably 50% by mass or less, and preferably 40% by mass or less (for example, 35% by mass or less).
The lower limit of the polymerization conversion is not particularly limited, but is typically 1% by mass or more, and usually 5% by mass or more.
The adhesive composition comprising a partial polymer of the monomer component can be obtained, for example, by: the monomer mixture containing all of the monomer components used in the preparation of the adhesive composition is partially polymerized using a suitable polymerization method (e.g., a photopolymerization method).
In addition, the adhesive composition containing a partial polymer of a monomer component may be a mixture of a partial polymer or a complete polymer of a monomer mixture containing a part of a monomer component (which is a monomer component used for preparation of the adhesive composition), and the remaining monomer component or a partial polymer thereof. In the present specification, the term "complete polymer" means that the polymerization conversion rate exceeds 95% by mass.
< oligomer >
One embodiment of the present invention is directed to an adhesive composition that may include at least one oligomer. The oligomer in one embodiment of the present invention is obtained by polymerizing a monomer composition containing at least a vinyl monomer having at least one dye structure in a side chain. That is, the oligomer contains at least a vinyl monomer having at least one dye structure in a side chain as a monomer unit.
In the pressure-sensitive adhesive composition according to one embodiment of the present invention, since an oligomer containing a vinyl monomer having a dye structure in a side chain as a structural unit is used as the dye component, problems of deterioration in dispersibility and bleeding of the dye when the pigment or dye is used can be avoided.
Examples of the vinyl monomer having at least one dye structure in the side chain include (meth) acrylic monomers, aromatic vinyl monomers, and aliphatic hydrocarbon monomers. From the viewpoint of good compatibility with the (meth) acrylic base polymer and maintaining transparency, a (meth) acrylic monomer is preferably used.
The (meth) acrylic monomer is not particularly limited. For example, the above-mentioned (meth) acrylic acid C1-20An alkyl ester; the various alicyclic hydrocarbon group-containing (meth) acrylates described above; the various aromatic hydrocarbon group-containing (meth) acrylates described above; a (meth) acrylic monomer such as a (meth) acrylate obtained from a terpene compound derivative alcohol. These may be used alone or in combination of two or more.
The aromatic vinyl monomer is not particularly limited. For example, styrene monomers such as styrene, chlorostyrene, chloromethylstyrene, and α -methylstyrene may be mentioned. These may be used alone or in combination of two or more.
The aliphatic hydrocarbon monomer is not particularly limited. For example, an olefin monomer, a diene monomer, and the like can be mentioned. These may be used alone or in combination of two or more.
The oligomer in one embodiment of the present invention may contain a monomer other than the vinyl monomer having at least one dye structure in the side chain. The monomer is not particularly limited as described above. Examples thereof include (meth) acrylic monomers, aromatic vinyl monomers, and aliphatic hydrocarbon monomers.
In the oligomer according to an embodiment of the present invention, the vinyl monomer having at least one dye structure in a side chain is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and further preferably 5 parts by mass or more, based on 100 parts by mass of the oligomer.
From the viewpoint of compatibility with the base polymer, it is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less.
As the oligomer in one embodiment of the present invention, a (meth) acrylic oligomer is preferable.
The (meth) acrylic oligomer may be a homopolymer of a (meth) acrylic monomer having at least one dye structure in a side chain.
The (meth) acrylic oligomer may be a copolymer of a "vinyl monomer having at least one dye structure in a side chain" and a "monomer other than a vinyl monomer having at least one dye structure in a side chain". In this case, the total amount of the "vinyl monomer having at least one dye structure in a side chain" and the "monomer other than the vinyl monomer having at least one dye structure in a side chain" is preferably 50% by mass or more of the monomer corresponding to the (meth) acrylic monomer. More preferably 70% by mass or more, and still more preferably 80% by mass or more.
The "monomer other than the vinyl monomer having at least one dye structure in the side chain" is preferably a "(meth) acrylic monomer having no dye structure in the side chain", and more preferably an "alkyl (meth) acrylate having no dye structure in the side chain".
When the (meth) acrylic oligomer is a copolymer of a "vinyl monomer having at least one dye structure in a side chain" and a "monomer other than a vinyl monomer having at least one dye structure in a side chain", a preferable combination is a combination of a "meth (acrylic monomer having at least one dye structure in a side chain" and a "meth (acrylic monomer having no dye structure in a side chain"). A more preferable combination is a combination of "a (meth) acrylic monomer having at least one dye structure in a side chain" and "an alkyl (meth) acrylate having no dye structure in a side chain".
As the (meth) acrylic monomer and the alkyl (meth) acrylate, those mentioned above can be used.
From the viewpoint of improving adhesiveness, the (meth) acrylic oligomer preferably contains, as a monomer unit, a (meth) acrylic monomer having a bulky structure represented by an alkyl (meth) acrylate having a branched structure of an alkyl group such as isobutyl (meth) acrylate or tert-butyl (meth) acrylate, a (meth) acrylate containing an alicyclic hydrocarbon group, a (meth) acrylate containing an aromatic hydrocarbon group, or the like.
In addition, when ultraviolet light is used for synthesizing a (meth) acrylic oligomer or for producing a pressure-sensitive adhesive layer, a monomer having a saturated hydrocarbon group at the ester terminal is preferable from the viewpoint of being less likely to cause inhibition of polymerization. For example, alkyl (meth) acrylates in which the alkyl group has a branched structure and (meth) acrylates containing a saturated alicyclic hydrocarbon group can be preferably used.
As the constituent monomer component of the (meth) acrylic oligomer, a functional group-containing monomer may be used as needed in addition to the above-mentioned (meth) acrylic monomer.
Examples of the functional group-containing monomer include: monomers having a nitrogen atom-containing heterocycle such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N, N-dimethylaminoethyl (meth) acrylate; amide group-containing monomers such as N, N-diethyl (meth) acrylamide; AA. Carboxyl group-containing monomers such as MAA; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate.
The above-mentioned functional group-containing monomers may be used singly or in combination of two or more. When the functional group-containing monomer is used, the proportion of the functional group-containing monomer in the total monomer components constituting the (meth) acrylic oligomer may be, for example, 1 mass% or more, 2 mass% or more, or 3 mass% or more. The proportion of the functional group-containing monomer may be, for example, 15 mass% or less, 10 mass% or less, or 7 mass% or less.
The oligomer in one embodiment of the present invention may have the same or different pigment structures in one molecule. In one embodiment of the present invention, the different pigment structures include not only pigment structures having different pigment skeletons but also pigment structures having the same pigment skeleton but having different types of substituents bonded to the pigment skeleton.
In one embodiment of the present invention, the dye structure refers to a structure derived from a dye compound. For example, there is a structure in which 1 or more arbitrary atoms of the dye compound are removed.
The type of the dye structure is not particularly limited, and may be appropriately selected depending on the purpose. The dye structure may be a structure derived from a dye compound having absorption in the visible light region (preferably, in the wavelength range of 400 to 700nm, more preferably, in the wavelength range of 400 to 650 nm). The dye compound may have a structure derived from a dye compound having absorption in the infrared region (preferably, a compound having a maximum absorption wavelength in the range of 700 to 1200 nm).
Among them, a structure derived from a dye compound having absorption in the visible light region is preferable.
Examples of the pigment structure include triarylmethane pigment structure, xanthene pigment structure, anthraquinone pigment structure, cyanine pigment structure, squarylium pigment structure, quinophthalone pigment structure, phthalocyanine pigment structure, subphthalocyanine pigment structure, azo pigment structure, pyrazolotriazole pigment structure, dipyrromethene pigment structure, isoindoline pigment structure, thiazole pigment structure, benzimidazolone pigment structure, perinone pigment structure, pyrrolopyrrole pigment structure, pyrrolopyrroledione pigment structure, diimmonium pigment structure, naphthalocyanine pigment structure, rylene pigment structure, dibenzofuranone pigment structure, merocyanine pigment structure, croconium pigment structure, and oxonol pigment structure.
Among them, triarylmethane dye structure, xanthene dye structure, and cyanine dye structure are preferable.
The vinyl monomer in one embodiment of the present invention may have at least one of the above-described dye structures in a side chain.
The oligomer in one embodiment of the present invention may be formed by: polymerizing a monomer composition containing at least a vinyl monomer having at least one pigment structure in a side chain. The polymerization method and polymerization method are not particularly limited, and various conventionally known polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, and radiation polymerization) can be used as appropriate.
The kind of the polymerization initiator (for example, azo-based polymerization initiator) that can be used according to need is generally as exemplified with respect to the synthesis of the (meth) acrylic polymer. The amount of the polymerization initiator and the amount of the chain transfer agent (for example, mercaptans such as n-dodecylmercaptan (NDM)) to be optionally used are appropriately set based on the technical common knowledge so that the desired molecular weight is obtained, and thus detailed description thereof is omitted.
The weight average molecular weight (Mw) of the oligomer in one embodiment of the present invention is preferably 1,000 to 50,000 from the viewpoint of compatibility with the base polymer. The weight average molecular weight (Mw) is more preferably 2,000 or more, and still more preferably 3,000 or more. The weight average molecular weight (Mw) is more preferably 25,000 or less, and still more preferably 10,000 or less.
The weight average molecular weight (Mw) herein means a value obtained by Gel Permeation Chromatography (GPC) in terms of standard polystyrene. The GPC apparatus may be, for example, a model name "HLC-8320 GPC" (column: TSKgel GMH-H (S), manufactured by Tosoh corporation). The same applies to the later-described embodiments. The Mw may be the Mw of the oligomer in either the adhesive composition or the adhesive layer.
In addition, from the viewpoint of good compatibility, the combination of the base polymer and the oligomer in one embodiment of the present invention is preferably a combination of a (meth) acrylic polymer and a (meth) acrylic oligomer.
The adhesive composition according to one embodiment of the present invention preferably contains the oligomer in an amount of 0.01 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 5 parts by mass or more, based on 100 parts by mass of the base polymer, from the viewpoint of coloring properties.
From the viewpoint of the influence on physical properties such as adhesive strength, the content of the oligomer is usually preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and still more preferably 80 parts by mass or less.
(other Components)
The pressure-sensitive adhesive composition according to one embodiment of the present invention may contain, as other optional components, various additives that are generally used in the field of pressure-sensitive adhesive compositions, such as tackifier resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, and ketone-based tackifier resins), viscosity modifiers (e.g., thickeners), leveling agents, plasticizers, fillers, stabilizers, preservatives, and anti-aging agents, as necessary, within a range that does not inhibit the effects of the present invention. Conventionally known additives can be used as such various additives by conventional methods, and a detailed description thereof will be omitted since the present invention is not particularly characterized.
The technique according to this embodiment can exhibit a good adhesive strength without using the above-described tackifier resin. Therefore, the content of the tackifier resin in the pressure-sensitive adhesive composition may be, for example, less than 10 parts by mass, and further less than 5 parts by mass, based on 100 parts by mass of the base polymer.
The content of the tackifier resin may be less than 1 part by mass (for example, less than 0.5 part by mass) and may be less than 0.1 part by mass (0 part by mass or more and less than 0.1 part by mass), and the pressure-sensitive adhesive composition may not contain the tackifier resin.
In the pressure-sensitive adhesive composition according to one embodiment of the present invention, it is preferable to limit the amount of the component other than the base polymer in the pressure-sensitive adhesive composition from the viewpoint of improving transparency and making coloring conspicuous by a coloring matter.
In the technique according to the present embodiment, the amount of the component other than the base polymer in the pressure-sensitive adhesive composition is usually 30% by mass or less, preferably 15% by mass or less, and preferably 12% by mass or less (for example, 10% by mass or less).
The amount of the component other than the base polymer in the pressure-sensitive adhesive composition according to one embodiment may be 5% by mass or less, may be 3% by mass or less, and may be 1.5% by mass or less (for example, 1% by mass or less). The composition in which the amount of the component other than the base polymer is limited in this way can be preferably used for the adhesive composition according to the present embodiment.
< adhesive layer >
The adhesive layer according to one embodiment of the present invention is formed from the adhesive composition. Fig. 1 is a schematic cross-sectional view showing one configuration example of the adhesive layer 11.
The adhesive layer may be a cured layer of the adhesive composition. That is, the adhesive layer may be formed by: after the adhesive composition is applied (for example, coated) to an appropriate surface, curing treatment is appropriately performed. When two or more curing treatments (drying, crosslinking, polymerization, and the like) are performed, they may be performed simultaneously or in multiple stages.
In the adhesive composition using a partial polymer (polymer slurry) of a monomer component, typically, a final copolymerization reaction is performed as the curing treatment. That is, a part of the polymer is subjected to further copolymerization to form a complete polymer.
For example, in the case of a photocurable adhesive composition, light irradiation is performed. If necessary, curing treatment such as crosslinking and drying may be performed.
For example, in the case where drying is required as a photocurable adhesive composition (for example, in the case of a photocurable adhesive composition in which a partial polymer of a monomer component is dissolved in an organic solvent), the composition may be dried and then photocured.
In the adhesive composition using a complete polymer, typically, the curing treatment is carried out by drying (heat drying) and crosslinking, if necessary. In the case of a solvent-based adhesive composition to which photocurability (photocrosslinking property) is imparted by addition of a polyfunctional monomer, the composition may be dried and then photocured.
Here, after drying the composition, the pressure-sensitive adhesive sheet obtained by the drying may be bonded to an adherend. The adhesive sheet described later can be used in the following manner: the attachment to the adherend is performed by a method including a step of photocuring the adherend after the attachment to the adherend.
The adhesive layer having a multilayer structure of two or more layers may be produced by bonding a previously formed adhesive layer. Alternatively, the second pressure-sensitive adhesive layer may be formed by applying a pressure-sensitive adhesive composition to a previously formed first pressure-sensitive adhesive layer and curing the pressure-sensitive adhesive composition.
When the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to be used in a bonding method in which the pressure-sensitive adhesive sheet is bonded to an adherend and then photocured has a multilayer structure, the pressure-sensitive adhesive layer to be photocured may be a partial layer (for example, one layer) or may be all layers included in the multilayer structure.
The application of the pressure-sensitive adhesive composition can be carried out using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.
As a method for providing a pressure-sensitive adhesive layer on a substrate, a pressure-sensitive adhesive sheet having a form of a substrate to be described later may be used a direct method in which a pressure-sensitive adhesive composition is directly applied to the substrate to form a pressure-sensitive adhesive layer, or a transfer method in which a pressure-sensitive adhesive layer formed on a release surface is transferred to a substrate.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 3 to 2000. mu.m.
In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and still more preferably 30 μm or more, from the viewpoint of adhesiveness to an adherend such as step-following property. The thickness of the pressure-sensitive adhesive layer may be 50 μm or more, may exceed 50 μm, may be 70 μm or more, may be 100 μm or more, and may be 120 μm or more.
In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 1000 μm or less, 700 μm or less, 500 μm or less, 300 μm or less, 200 μm or less, or 170 μm or less, from the viewpoint of preventing the occurrence of residual powder slurry due to cohesive failure of the pressure-sensitive adhesive layer. The technique according to this embodiment can be suitably implemented in the form of a pressure-sensitive adhesive sheet described later in which the thickness of the pressure-sensitive adhesive layer is 130 μm or less, 90 μm or less, or 60 μm or less (for example, 40 μm or less).
In the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a multilayer structure of two or more layers, the thickness of the pressure-sensitive adhesive layer is a thickness from a pressure-sensitive adhesive surface to be adhered to an adherend to a surface opposite to the pressure-sensitive adhesive surface.
< adhesive sheet >
The pressure-sensitive adhesive sheet according to one embodiment of the present invention has the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to one embodiment of the present invention may be a substrate-attached pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one surface or both surfaces of a sheet-like substrate (support), or may be a substrate-free pressure-sensitive adhesive sheet having a form in which a pressure-sensitive adhesive layer is held on a release sheet. The concept of the adhesive sheet as referred to herein may include articles called adhesive tapes, adhesive labels, adhesive films, and the like.
The pressure-sensitive adhesive layer is typically formed continuously, but is not limited to this form, and may be formed in a regular or irregular pattern such as dots or stripes, for example. The pressure-sensitive adhesive sheet according to an embodiment of the present invention may be in a roll form or a sheet form. Alternatively, the pressure-sensitive adhesive sheet may be further processed into various shapes.
(substrate)
The adhesive sheet according to some embodiments may be in the form of a substrate-attached adhesive sheet (which includes a substrate attached to the other back surface of the adhesive layer). Fig. 2 is a schematic cross-sectional view showing an example of a configuration in which an adhesive layer is formed on one surface of a substrate in the adhesive sheet according to an embodiment of the present invention.
The adhesive sheet 1 shown in fig. 2 includes a substrate 21 and an adhesive layer 11 formed on one surface of the substrate. As another embodiment, fig. 3 is a schematic cross-sectional view showing one configuration example in which adhesive layers are formed on both surfaces of the base material 21. The adhesive sheet 2 shown in fig. 3 includes a substrate 21, and a1 st adhesive layer 11 and a2 nd adhesive layer 12 formed on both surfaces of the substrate.
The material of the substrate is not particularly limited, and may be appropriately selected depending on the purpose of use, the mode of use, and the like of the adhesive sheet. Preferably a transparent film.
Non-limiting examples of substrates that can be used include: plastic films such as polyolefin films mainly composed of polyolefins such as polypropylene and ethylene-propylene copolymers, polyester films mainly composed of polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyvinyl chloride films mainly composed of polyvinyl chloride; foam sheets formed from foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics formed from various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semisynthetic fibers such as acetate, etc.) alone or in a blended form; papers such as japanese paper, high-quality paper, kraft paper, and crepe paper; metal foils such as aluminum foil and copper foil; and so on. The substrate may be a composite substrate.
Examples of the substrate having such a composite structure include a substrate having a structure in which a metal foil and the plastic film are laminated, a plastic sheet reinforced with inorganic fibers such as glass cloth, and the like.
As the substrate of the pressure-sensitive adhesive sheet according to one embodiment of the present invention, various films (hereinafter, also referred to as support films) can be preferably used. The support film may be a porous film such as a foam film or a nonwoven fabric sheet, a non-porous film, or a film having a structure in which a porous layer and a non-porous layer are laminated.
In some embodiments, as the support film, a film containing a (self-supporting or independent) resin film capable of independently maintaining a shape as a base film can be preferably used.
The "resin film" herein is a non-porous structure, and typically means a resin film substantially free of bubbles (non-porous). Therefore, the resin film is a concept distinguished from a foam film and a nonwoven fabric. The resin film may have a single-layer structure or a multilayer structure (for example, a three-layer structure) of two or more layers.
As the resin material constituting the resin film, for example, resins such as polyesters, polyolefins, polycycloolefins derived from monomers having an aliphatic ring structure such as a norbornene structure, Polyamides (PA) such as nylon 6, nylon 66, and partially aromatic polyamides, Polyimides (PI), Polyamideimides (PAI), Polyetheretherketones (PEEK), Polyethersulfones (PES), polyphenylene sulfides (PPS), Polycarbonates (PC), Polyurethanes (PU), fluororesins such as ethylene-vinyl acetate copolymers (EVA), polystyrenes, polyvinyl chlorides, polyvinylidene chlorides, and Polytetrafluoroethylene (PTFE), acrylic resins such as polymethyl methacrylates, cellulose polymers such as cellulose diacetate and cellulose triacetate, vinyl butyral polymers, acrylate polymers, polyoxymethylene polymers, and epoxy polymers can be used.
The resin film may be one formed using a resin material containing one kind of such resin alone, or one formed using a resin material obtained by mixing two or more kinds of resins together. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).
Preferable examples of the resin material constituting the resin film include polyester-based resins, PPS resins, and polyolefin-based resins. The polyester resin here means a resin containing a polyester at a ratio of more than 50% by mass. Similarly, the PPS resin refers to a resin containing PPS in a proportion of more than 50 mass%, and the polyolefin resin refers to a resin containing polyolefin in a proportion of more than 50 mass%.
As the polyester resin, typically, a polyester resin containing as a main component a polyester obtained by polycondensation of a dicarboxylic acid and a diol can be used. Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.
As the polyolefin resin, one kind of polyolefin may be used alone, or two or more kinds of polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of an α -olefin, a copolymer of two or more α -olefins, a copolymer of one or more α -olefins with another vinyl monomer, or the like.
Specific examples thereof include ethylene-propylene copolymers such as Polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene and Ethylene Propylene Rubber (EPR), ethylene-propylene-butene copolymers, ethylene-vinyl alcohol copolymers and ethylene-ethyl acrylate copolymers. Any of Low Density (LD) polyolefin and High Density (HD) polyolefin may be used.
Examples of the polyolefin resin film include an unstretched polypropylene (CPP) film, a biaxially stretched polypropylene (OPP) film, a Low Density Polyethylene (LDPE) film, a Linear Low Density Polyethylene (LLDPE) film, a Medium Density Polyethylene (MDPE) film, a High Density Polyethylene (HDPE) film, a Polyethylene (PE) film obtained by blending two or more types of Polyethylene (PE), a PP/PE blend film obtained by blending polypropylene (PP) and Polyethylene (PE), and the like.
Specific examples of the resin film which can be preferably used as the substrate include a PET film, a PEN film, a PPS film, a PEEK film, a CPP film, and an OPP film.
From the viewpoint of strength, preferable examples include a PET film, a PEN film, a PPS film, and a PEEK film. From the viewpoint of availability, dimensional stability, optical characteristics, and the like, a PET film is a preferred example.
The resin film may contain known additives such as a light stabilizer, an antioxidant, an antistatic agent, a colorant (dye, pigment, etc.), a filler, a slip agent, and an antiblocking agent, as required. The amount of the additive to be blended is not particularly limited, and may be appropriately set according to the use of the pressure-sensitive adhesive sheet and the like.
The method for producing the resin film is not particularly limited. For example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be suitably used.
The substrate may be substantially composed of such a resin film. Alternatively, the substrate may further include an auxiliary layer in addition to the resin film.
Examples of the auxiliary layer include an optical property adjusting layer (e.g., an antireflection layer), a printing layer for giving a desired appearance to a substrate or an adhesive sheet, a lamination layer, an antistatic layer, an undercoat layer, and a surface treatment layer such as a release layer. The substrate may be an optical member described later.
The thickness of the substrate is not particularly limited, and may be selected according to the purpose of use, the mode of use, and the like of the adhesive sheet. The thickness of the substrate may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, and 5 μm or less.
When the thickness of the substrate is small, the flexibility of the pressure-sensitive adhesive sheet and the following property to the surface shape of the adherend tend to be improved. The thickness of the base material may be, for example, 2 μm or more, and may be more than 5 μm or more than 10 μm from the viewpoint of workability, processability, and the like. In some embodiments, the thickness of the substrate may be, for example, 20 μm or more, 35 μm or more, and 55 μm or more.
The surface of the substrate on the side to be bonded to the adhesive layer may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, coating with a primer (primer), and antistatic treatment, as required.
Such surface treatment may be treatment for improving adhesion between the base material and the adhesive layer, in other words, anchoring property of the adhesive layer to the base material. The composition of the primer is not particularly limited, and may be appropriately selected from known ones.
The thickness of the undercoat layer is not particularly limited, but is usually preferably 0.01 to 1 μm, more preferably 0.1 to 1 μm.
A surface of the substrate opposite to the side to be bonded to the pressure-sensitive adhesive layer (hereinafter also referred to as a back surface) may be subjected to conventionally known surface treatment such as a peeling treatment, a treatment for improving adhesiveness or adhesiveness, an antistatic treatment, or the like, as necessary.
For example, the surface treatment of the back surface of the substrate with the release treatment agent can reduce the unwinding force of the adhesive sheet wound in a roll form. Examples of the release treatment agent include silicone release treatment agents, long-chain alkyl release treatment agents, olefin release treatment agents, fluorine release treatment agents, fatty acid amide release treatment agents, molybdenum sulfide, and silica powder.
(Release liner)
In the pressure-sensitive adhesive sheet according to one embodiment of the present invention, the pressure-sensitive adhesive layer may be protected by a release liner (release film ) until use.
The release liner is not particularly limited, and conventional release paper or the like can be used. For example, a substrate having a release treatment layer, a low-adhesion substrate made of a fluorine-based polymer, a low-adhesion substrate made of a nonpolar polymer, or the like can be used.
Examples of the substrate having a release-treated layer include plastic films and papers which are surface-treated with a release-treating agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.
Examples of the fluorine-based polymer of the low adhesion base material made of a fluorine-based polymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer.
Examples of the nonpolar polymer of the low-adhesion substrate made of the nonpolar polymer include olefin resins (for example, polyethylene, polypropylene, and the like). The release liner may be formed by a known or conventional method. The thickness of the release liner is not particularly limited.
In the technique according to this embodiment, the haze value of the pressure-sensitive adhesive sheet is preferably 10% or less, and may be 5% or less (for example, 3% or less). The haze value is preferably 1.0% or less. Such a pressure-sensitive adhesive sheet having high transparency is preferable in view of the remarkable change in appearance upon discoloration or coloring in one embodiment of the present invention.
The haze value of the adhesive sheet may be less than 1.0%, less than 0.7%, or 0.5% or less (e.g., 0 to 0.5%). These haze values relating to the pressure-sensitive adhesive sheet can be favorably applied to the haze value of the pressure-sensitive adhesive layer in the technique according to the present embodiment.
The "haze value" herein refers to a ratio of diffuse transmitted light to total transmitted light when the measurement object is irradiated with visible light. Also known as haze. The haze value may be represented by the following formula.
Th[％]＝Td/Tt×100
In the above formula, Th is a haze value [% ], Td is a scattered light transmittance, and Tt is a total light transmittance. The haze value can be measured by the method described in examples described later. The haze value can be adjusted, for example, by selecting the composition, thickness, etc. of the adhesive layer.
The technique according to the present embodiment can be preferably used for electronic component applications, optical component applications, building component applications, and the like.
Examples
Hereinafter, embodiments of the present invention will be described in detail with reference to examples.
< preparation of adhesive composition >
[ preparation of adhesive solution ]
(adhesive solution A1)
In a reaction vessel equipped with a condenser tube, a nitrogen gas inlet tube, a thermometer, and a stirrer, 97 parts by mass of n-Butyl Acrylate (BA), 2 parts by mass of Acrylic Acid (AA), 1 part by mass of 4-hydroxybutyl acrylate (4HBA), and 122 parts by mass of ethyl acetate as a polymerization solvent were charged as monomer components, 0.2 part by mass of 2, 2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added, and solution polymerization was performed under a nitrogen atmosphere, thereby obtaining a binder solution a1 containing a (meth) acrylic polymer having Mw of 70 ten thousand.
(adhesive solution A2)
A binder solution a2 having an Mw of 65 ten thousand was prepared in the same manner as in the preparation of the binder solution a1, except that the monomer components were 95 parts by mass of n-Butyl Acrylate (BA), 5 parts by mass of Acrylic Acid (AA), and 0 part by mass of 4-hydroxybutyl acrylate (4 HBA).
(adhesive solution A3)
A binder solution A3 having an Mw of 60 ten thousand was prepared in the same manner as in the preparation of the binder solution a1, except that the monomer components were 95 parts by mass of n-Butyl Acrylate (BA), 0 part by mass of Acrylic Acid (AA), and 5 parts by mass of 4-hydroxybutyl acrylate (4 HBA).
The formulation of the binder solution is summarized in table 1 below.
[ Table 1]
TABLE 1
Figure BDA0003281778000000321
[ preparation of dye oligomer solution ]
(dye oligomer solution B1)
A dye oligomer solution B1 containing a (meth) acrylic blue dye oligomer having an Mw of 5,000 was obtained by adding 90 parts by mass of n-Butyl Acrylate (BA) as a monomer component, 10 parts by mass of a blue polymerizable dye RDW-B01 (manufactured by fuji film and Wako pure chemical industries, Ltd.) as a vinyl monomer having a dye structure in a side chain, 5 parts by mass of n-dodecylmercaptan (NDM) as a chain transfer agent, and 122 parts by mass of ethyl acetate as a polymerization solvent to a reaction vessel equipped with a condenser tube, a nitrogen gas inlet tube, a thermometer, and a stirrer, and by adding 0.2 parts by mass of 2, 2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator and carrying out solution polymerization under a nitrogen atmosphere.
(dye oligomer solution B2)
A dye oligomer solution B2 having an Mw of 5,000 was obtained in the same manner as in the preparation of dye oligomer B1, except that 10 parts by mass of RDW-Y02 (fuji film, wako pure chemical industries, Ltd.) having a yellow polymerizable dye was used.
(dye oligomer solution B3)
A dye oligomer solution B3 having Mw of 1,300 was obtained in the same manner as in the preparation of the dye oligomer B1, except that the amount of n-dodecylmercaptan (NDM) used was 20 parts by mass relative to 100 parts by mass of the monomer component.
(dye oligomer solution B4)
A dye oligomer solution B4 having an Mw of 48,000 was obtained in the same manner as in the preparation of the dye oligomer B1, except that the amount of n-dodecylmercaptan (NDM) used was 0.1 part by mass relative to 100 parts by mass of the monomer component.
(dye oligomer solution B5)
A dye oligomer solution B4 having Mw of 600 was obtained in the same manner as in the preparation of the dye oligomer B1, except that the amount of n-dodecylmercaptan (NDM) used was changed to 30 parts by mass based on 100 parts by mass of the monomer component.
(dye oligomer solution B6)
A dye oligomer solution B6 having Mw of 120,000 was obtained in the same manner as in the preparation of the dye oligomer B1, except that the amount of n-dodecylmercaptan (NDM) used was 0.02 parts by mass relative to 100 parts by mass of the monomer component.
The formulation of the dye oligomer solution is summarized in the following table 2.
[ Table 2]
TABLE 2
Figure BDA0003281778000000331
[ production of adhesive composition ]
(adhesive composition C1)
To the adhesive solution a1 obtained above, 1 part by mass of the dye oligomer solution B1 and 0.8 part by mass of an isocyanate-based crosslinking agent Coronate L (manufactured by tokyo) were added and uniformly mixed with respect to 100 parts by mass of the polymer component used for the preparation of the solution, to prepare an adhesive composition C1.
(adhesive composition C2)
An adhesive composition C2 was prepared in the same manner as in the preparation of the adhesive composition C1, except that the amount of the dye oligomer solution B1 used was 5 parts by mass.
(adhesive composition C3)
A pressure-sensitive adhesive composition C3 was prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition C2, except that the pressure-sensitive adhesive solution used was the pressure-sensitive adhesive solution a2 and 0.08 parts by mass of Tetrad C (manufactured by mitsubishi gas chemical) was used instead of 0.8 parts by mass of Coronate L.
(adhesive composition C4)
An adhesive composition C4 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the adhesive solution used was the adhesive solution a 3.
(adhesive composition C5)
An adhesive composition C5 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the dye oligomer solution B1 was changed to 2.5 parts by mass and the dye oligomer solution B2 was changed to 2.5 parts by mass.
(adhesive composition C6)
An adhesive composition C6 was prepared in the same manner as in the preparation of adhesive composition C2, except that the dye oligomer solution B1 was changed to 2.5 parts by mass, and 2.5 parts by mass of organic Pigment Blue 15 (manufactured by tokyo chemical industry) and 0.5 part by mass of dispersant Ajisper PB821 (manufactured by Ajinomoto Fine-Techno) were added.
(adhesive composition C7)
An adhesive composition C7 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the dye oligomer solution used was the dye oligomer solution B3.
(adhesive composition C8)
An adhesive composition C8 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the dye oligomer solution used was the dye oligomer solution B4.
(adhesive composition C9)
An adhesive composition C9 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the dye oligomer solution used was the dye oligomer solution B5.
(adhesive composition C10)
An adhesive composition C10 was prepared in the same manner as in the preparation of the adhesive composition C2, except that the dye oligomer solution used was the dye oligomer solution B6.
(adhesive composition C11)
An adhesive composition C11 was prepared in the same manner as in the preparation of the adhesive composition C1, except that 1 part by mass of the organic Pigment Blue 15 was used instead of the dye oligomer solution B1.
(adhesive composition C12)
An adhesive composition C12 was prepared in the same manner as in the preparation of the adhesive composition C11, except that the organic Pigment was changed to 2.5 parts by mass of Pigment Blue 15 and 2.5 parts by mass of Pigment Yellow 74 (manufactured by Oakwood Products, inc.).
(adhesive composition C13)
An adhesive composition C13 was prepared in the same manner as in the preparation of the adhesive composition C1, except that the dye oligomer solution B1 was not used.
(adhesive composition C14)
An adhesive composition C14 was prepared in the same manner as in the preparation of adhesive composition C11, except that 0.5 part by mass of dispersant Ajisper PB821 (manufactured by Ajinomoto Fine-Technio) was added.
(adhesive composition C15)
An adhesive composition C15 was prepared in the same manner as in the preparation of the adhesive composition C14, except that the amount of the organic Pigment Blue 15 used was 5 parts by mass.
(adhesive composition C16)
A pressure-sensitive adhesive composition C16 was prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition C15, except that the pressure-sensitive adhesive solution used was the pressure-sensitive adhesive solution a3, 0.08 parts of Tetrad C (manufactured by mitsubishi gas chemical) was used in place of 0.8 parts by mass of Coronate L, and no dispersant was used.
< production of adhesive sheet >
(example 1)
A38 μm thick release film R1 (Mitsubishi resin corporation, MRF #38) having one side of a polyester film as a release surface was coated with the pressure-sensitive adhesive composition C1 and dried at 135 ℃ for 2 minutes to form a 30 μm thick pressure-sensitive adhesive layer. A polyethylene terephthalate (PET) film having a thickness of 75 μm and subjected to corona treatment was bonded to the pressure-sensitive adhesive layer, thereby obtaining a pressure-sensitive adhesive sheet 1 in which a PET film (support), a pressure-sensitive adhesive layer, and a release film R1 were sequentially laminated.
(examples 2 to 10)
Adhesive sheets 2 to 10 were produced in the same manner as in example 1, except that adhesive compositions C2 to C10 were used instead of the adhesive composition C1, respectively.
Comparative examples 1 and 2
Adhesive sheets 11 and 12 were produced in the same manner as in example 1, except that adhesive compositions C11 and C12 were used instead of adhesive composition C1, respectively.
(reference examples 1 to 4)
Adhesive sheets 13 to 16 according to each example were produced in the same manner as in example 1, except that adhesive compositions C13 to C16 were used instead of adhesive composition C1, respectively.
< evaluation of dispersibility >
The dispersibility of the dye oligomer or the known organic pigment in the adhesive sheets 1 to 16 prepared as described above was evaluated by the degree of the presence of aggregates as described below.
O (good dispersibility): no visually recognizable aggregates were observed in the test piece of 10cm × 10cm
Δ (slightly better dispersion): less than 10 visually recognizable aggregates were observed in a test piece of 10cm × 10cm
X (poor dispersibility): more than 10 visually recognizable aggregates were observed in a test piece of 10cm × 10cm
The results are shown in Table 3. In table 3, "-" means that the evaluation was not performed.
< evaluation of bleeding >
The bleeding properties of the pressure-sensitive adhesive sheets 1 to 16 produced as described above were evaluated by the degree of residue of the colorant component on the adherend after peeling, as described below. The remaining region of the dye component in the following evaluation was obtained as follows: the specific gravity of the pressure-sensitive adhesive layer was set to 1.17g/cm3The change in weight of the pressure-sensitive adhesive sheet before and after peeling was measured.
O (good bleeding): in a peeled surface of 2.5 cm. times.7 cm, no residue of the coloring matter component was observed
Δ (slightly good bleeding): in a 2.5cm × 7cm peeled surface, the residue of the dye component was observed in a region of less than 10%
X (poor bleeding property): in a 2.5cm × 7cm peeled surface, the residue of the dye component was observed in a region of 10% or more
The results are shown in Table 3. In table 3, "-" means that the evaluation was not performed.
< determination of adhesion >
The adhesive force was measured for the adhesive sheets 1 to 16 produced as described above.
For the measurement of the adhesive force, the adhesive sheets 1 to 16 were each cut into a width of 25mm and a length of 10cm, and the release liner was peeled off and removed.
Subsequently, the 2kg roller was reciprocated 1 time, and each adhesive sheet was pressure-bonded and stuck to acrylic glass.
The force at the time of peeling was measured using a tensile tester (AUTOGRAPH AGS-X, manufactured by Shimadzu corporation) under conditions of a peeling angle of 180 degrees and a peeling speed of 300mm/min, and the force was used as an adhesive force (N/25 mm).
The results are shown in Table 3. In table 3, "-" means that the measurement was not performed.
[ Table 3]
Figure BDA0003281778000000381
The adhesive sheets of examples 1 to 10 containing the dye oligomer were excellent in both dispersibility and bleeding property. Among them, examples 1 to 8 in which the weight average molecular weight (Mw) of the dye oligomer was 1,000 to 50,000 showed particularly good dispersibility and bleeding property. In addition, the adhesive sheet of example 6 contains a pigment, but also contains a dispersant, and therefore, good results were obtained.
On the other hand, the pressure-sensitive adhesive sheets of comparative examples 1 and 2 contained a pigment instead of a dye oligomer, and therefore were poor in both dispersibility and bleeding property.
In the pressure-sensitive adhesive sheets of reference examples 2 and 3, a dispersant was added to the pressure-sensitive adhesive composition of comparative example 1. Therefore, the pressure-sensitive adhesive sheets of comparative example 1 were poor in both dispersibility and bleeding property, but the pressure-sensitive adhesive sheets of reference examples 2 and 3 were good in both dispersibility and bleeding property. In addition, in the pressure-sensitive adhesive sheet of reference example 4, since a pressure-sensitive adhesive solution containing a polymer having a high acid value was used, both dispersibility and bleeding property were good.
While the various embodiments have been described above with reference to the drawings, it is needless to say that the present invention is not limited to these examples. It is understood by those skilled in the art that various changes and modifications can be made within the scope of the claims and that these are also within the technical scope of the present invention. In addition, the respective components in the above embodiments may be arbitrarily combined without departing from the scope of the invention.
It should be noted that the present application is based on japanese patent application filed on 28/3/2019 (japanese patent application 2019-065069), the contents of which are incorporated herein by reference.
Description of the reference numerals
1. 2 pressure-sensitive adhesive sheet
11. 12 adhesive layer
21 base material

Claims (9)

1. An adhesive composition comprising a base polymer and at least one oligomer obtained by polymerizing a monomer composition containing at least a vinyl monomer having at least one pigment structure in a side chain.
2. The adhesive composition of claim 1, wherein the base polymer is a (meth) acrylic polymer.
3. Adhesive composition according to claim 1 or 2, wherein the oligomer is a (meth) acrylic oligomer.
4. The adhesive composition according to claim 3, wherein the (meth) acrylic oligomer is a homopolymer of a (meth) acrylic monomer having at least one pigment structure in a side chain.
5. The adhesive composition according to claim 3, wherein the (meth) acrylic oligomer is a copolymer of a (meth) acrylic monomer having at least one pigment structure in a side chain and an alkyl (meth) acrylate.
6. The adhesive composition according to any one of claims 1 to 5, wherein the oligomer has a weight average molecular weight of 1,000 to 50,000.
7. An adhesive layer formed from the adhesive composition according to any one of claims 1 to 6.
8. A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 7.
9. The adhesive sheet according to claim 8, wherein the adhesive layer is provided on a transparent film.
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