JP5434773B2 - Adhesive for decorative sheet and decorative sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive for decorative pressure-sensitive adhesive sheets used for the purpose of advertising and decoration of articles such as signs, buildings, vehicles, and the like.

Conventionally, a decorative sheet in which an adhesive layer is formed on a colored PVC base material for signboard use has been used. This decorative sheet is also called a marking sheet. Furthermore, it may be used by giving design properties by printing on a PVC base material.
Recently, with the diversification of advertising methods, the use of decorative sheets for vehicles such as automobiles, trucks, buses, trains, etc. is increasing in addition to signboard applications.
Therefore, the pressure-sensitive adhesive used for the decorative sheet has high outdoor weather resistance, is in close contact with an unpainted PP bumper or the like, and needs a sufficient adhesive force that does not cause lifting or peeling even when it is applied to an uneven surface. On the other hand, after use, re-peelability that can be peeled without adhesive residue is required.

  Therefore, Patent Document 1 proposes a pressure-sensitive adhesive that uses alkyl methacrylate as a re-peeling adhesive for the purpose of suppressing an increase in peel force with time, and uses 43 parts by weight of iso-butyl methacrylate in Example 2. Has been. However, since this adhesive has a high glass transition temperature and low tack and adhesive strength, it is not suitable for the intended use of the present invention.

  Patent Document 2 discloses that 100 parts by weight of an adhesive polymer having a weight average molecular weight of 600,000 or more obtained by copolymerizing an alkoxyalkyl ester of acrylic acid as a main component and a carboxyl group-containing monomer, and an alkyl methacrylate. A low molecular weight polymer having a glass transition temperature of 60 ° C. or more and a weight average molecular weight of 50,000 or less, obtained by copolymerizing an amino group-containing monomer with the monomer, and a crosslinking agent Agent compositions have been proposed. However, since this adhesive is supposed to be used for FDP and touch panel, it has insufficient adhesive strength to olefins such as PP, and is not suitable for this application used outdoors in winter.

JP 2002-363521 A JP 2002-327160 A

  The present invention has high outdoor weather resistance, good adhesion to olefin-based materials such as PP used for bumpers, etc., even when stuck on an uneven surface, no lifting or peeling occurs, after use The purpose is to provide an adhesive used for decorative sheets that can be peeled off without leaving glue

The present invention includes an acrylic polymer (A) formed by solution polymerization having a glass transition temperature of −70 to −10 ° C. and a weight average molecular weight of 800,000 to 2 million, a glass transition temperature of −10 ° C. or more and less than 40 ° C., and A pressure-sensitive adhesive comprising an acrylic polymer (B) formed by solution polymerization having a weight average molecular weight of 1 to 100,000 or less, and a crosslinking agent (C),
The acrylic polymer (B) is a copolymer obtained by reacting at least a methacrylic acid alkyl ester having an alkyl chain having 2 to 6 carbon atoms,
Furthermore, it is related with the adhesive for decorative sheets characterized by using the said acrylic polymer (A) and the said acrylic polymer (B) by weight ratio 50 / 50-95 / 5.

  Moreover, this invention relates to the adhesive for decorative sheets of the said invention characterized by the acrylic polymer (B) containing a carboxyl group and / or an amino group further.

  The present invention also relates to a decorative sheet formed by forming a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for decorative sheets of the above invention on a sheet-like substrate.

  The present invention also relates to a vehicle using the decorative sheet of the above invention.

  According to the present invention, outdoor weather resistance is high, olefin materials such as PP used for bumpers and the like have good adhesiveness, and there is sufficient adhesive strength that does not cause peeling even when stuck on an uneven surface. After use, it was possible to provide a pressure-sensitive adhesive for a decorative sheet that could be peeled off without leaving glue.

The pressure-sensitive adhesive for decorative sheets of the present invention comprises an acrylic polymer (A) formed by solution polymerization having a glass transition temperature of −70 to −10 ° C. and a weight average molecular weight of 800,000 to 2 million, and a glass transition temperature of −10 ° C. or higher. A pressure-sensitive adhesive containing an acrylic polymer (B) formed by solution polymerization having a weight average molecular weight of 1 to 100,000 or less and a crosslinking agent (C) at less than 40 ° C.,
The acrylic polymer (B) is a copolymer obtained by reacting at least a methacrylic acid alkyl ester having an alkyl chain having 2 to 6 carbon atoms,
Furthermore, it is important to use the acrylic polymer (A) and the acrylic polymer (B) in a weight ratio of 50/50 to 95/5.

In the present invention, the acrylic polymer (A) is a high molecular weight polymer and has a high cohesive force, so that it imparts cohesive force to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, and does not cause floating or peeling even when applied outdoors. It has a function.
On the other hand, in the present invention, the acrylic polymer (B) is a polymer having a relatively low molecular weight, and has a function of improving the adhesion of the pressure-sensitive adhesive layer to the olefinic adherend and the followability to the uneven surface. Therefore, it is important that the weight average molecular weight is 1 to 100,000 or less. Furthermore, it is important that the acrylic polymer (B) has a glass transition temperature of −10 ° C. or higher and lower than 40 ° C., but in order to achieve the above function, the monomer used has at least an alkyl chain having 2 to 6 carbon atoms. It is important that it is a methacrylic acid alkyl ester.
The pressure-sensitive adhesive for decorative sheets of the present invention is used as a decorative sheet by using these two types of polymers (A) and (B) in a weight ratio of 50/50 to 95/5 and further using a crosslinking agent (C). The olefinic adherend and the uneven surface have good followability, do not float or peel off, and have excellent characteristics that can be peeled off with no adhesive residue even after aging.

  In the present invention, the acrylic polymer (A) preferably has at least one of a carboxyl group and a hydroxyl group as a functional group involved in the reaction with the crosslinking agent (C) described later. In order for the acrylic polymer (A) to have at least one of a carboxyl group or a hydroxyl group, a copolymerizable monomer having at least one of a carboxyl group or a hydroxyl group is used.

Examples of carboxyl group-containing monomers include (meth) acrylic acid, itaconic anhydride, itaconic acid, crotonic acid, maleic anhydride, maleic acid, 2- (meth) acryloyloxyethyl succinic acid, and 2-acryloyloxyethyl phthalic acid. 2- (meth) acryloyloxyethyl hexahydrophthalic acid and the like.
Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl. (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylhexyl) -methyl acrylate, chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) Examples include acrylates, caprolactone-modified (meth) acrylates, polyethylene glycol (meth) acrylates, and polypropylene glycol (meth) acrylates.

Examples of the other copolymerizable monomer used for the synthesis of the acrylic polymer (A) in the present invention include compounds having an ethylenically unsaturated double bond, and the acrylic monomer has weather resistance and adhesive properties. To preferred.
For example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl acrylate, t- (meth) acrylate Butyl, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, (meth) acrylic acid Alkyl (meth) acrylates such as decyl, dodecyl (meth) acrylate, octadecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate;
(Meth) acrylic acid cyclic esters such as cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate;
Allyl (meth) acrylate, 1-methylallyl (meth) acrylate, 2-methylallyl (meth) acrylate, 1-butenyl (meth) acrylate, 2-butenyl (meth) acrylate, (meth) acrylic acid 3- Butenyl, 1,3-methyl-3-butenyl (meth) acrylate, 2-chloroallyl (meth) acrylate, 3-chloroallyl (meth) acrylate, o-allylphenyl (meth) acrylate, (meth) acrylic acid 2- (allyloxy) ethyl, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, geranyl (meth) acrylate, rosinyl (meth) acrylate, cinnamyl (meth) acrylate, vinyl (meth) acrylate, etc. Unsaturated group-containing (meth) acrylic acid esters;
Heterocycle-containing (meth) acrylic acid esters such as (meth) acrylic acid glycidyl, (meth) acrylic acid (3,4-epoxycyclohexyl) methyl, (meth) acrylic acid tetrahydrofurfuryl;
Amino groups such as N-methylaminoethyl (meth) acrylate, N-tributylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and N, N-diethylaminoethyl (meth) acrylate Containing (meth) acrylic acid esters;
Alkoxysilyl such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltriisopropoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane Group-containing (meth) acrylic acid esters;
(Meth) acrylic acid derivatives such as (meth) acrylic acid methoxyethyl, ethylene oxide adducts of (meth) acrylic acid;
(Meth) acrylic acid perfluoroalkyl esters such as (meth) acrylic acid perfluoroethyl, (meth) acrylic acid perfluoropropyl, (meth) acrylic acid perfluorobutyl, (meth) acrylic acid perfluorooctyl;
Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, 1,1,1-trishydroxymethylethane diacrylate, 1,1,1-trishydroxymethylethane triacrylate, 1,1, 1-trishydroxymethylpropane polyfunctional (meth) acrylic acid esters such as triacrylic acid;
Perfluoromethyl (meth) acrylate, trifluoromethyl methyl (meth) acrylate, 2-trifluoromethyl ethyl (meth) acrylate, diperfluoromethyl methyl (meth) acrylate, 2-par (meth) acrylate Fluoroethylethyl, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, triperfluoromethylmethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate Fluorine-containing (meth) acrylic acid esters such as 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, 2-perfluorohexadecylethyl (meth) acrylate;
Examples thereof include, but are not limited to, acrylic monomers. These may use only 1 type or may use multiple types together.

Other monomers such as vinyl monomers copolymerizable with acrylic monomers can also be used.
For example, aromatic vinyl systems such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1-butylstyrene, chlorostyrene, styrenesulfonic acid and sodium salts thereof monomer;
Trialkyloxysilyl group-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane;
silicon-containing vinyl monomers such as γ- (methacryloyloxypropyl) trimethoxysilane;
Nitrile group-containing vinyl monomers such as acrylonitrile and methacrylonitrile;
Amide group-containing vinyl monomers such as acrylamide and methacrylamide;
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl cinnamate;
Fluorine-containing monomers such as perfluoroethylene, perfluoropropylene, vinylidene fluoride; and the like, but are not particularly limited thereto. These may use only 1 type or may use multiple types together.

  The carboxyl group-containing monomer is preferably used in an amount of 1 to 10% by weight out of 100% by weight of all monomers from the viewpoint of adhesive strength and cohesive strength. More preferably, it is 4 to 8% by weight. When the carboxyl group-containing monomer is less than 1% by weight, it is difficult to obtain a sufficient adhesive force, and the cohesive force of the pressure-sensitive adhesive layer tends to be reduced. On the other hand, if the monomer having a carboxyl group is used in an amount of more than 10% by weight, the adhesion to the tack or the substrate tends to be lowered.

  The hydroxyl group-containing monomer is preferably used in an amount of 0.1 to 5% by weight out of 100% by weight of all monomers. More preferably, it is 0.1 to 2% by weight. If it is less than 0.1% by weight, it is difficult to obtain a sufficient adhesive force, the cohesive force of the pressure-sensitive adhesive layer tends to decrease, and the adhesive remains easily at the time of peeling. On the other hand, if the monomer having a hydroxyl group is used in an amount of more than 5% by weight, the adhesion to the tack and the substrate tends to be lowered.

  The glass transition temperature (Tg) of the acrylic polymer is preferably −70 to −10 ° C., more preferably −55 to −30 ° C. When Tg is less than −70 ° C., the cohesive force of the pressure-sensitive adhesive layer decreases, and in order to obtain a cohesive force that does not leave adhesive during peeling, the amount of the necessary cross-linking agent is increased. When the uneven surface of the vehicle is affixed, there is a risk of floating or peeling. On the other hand, when Tg exceeds −10 ° C., sufficient adhesive strength and tack cannot be obtained, and the adhesion to the substrate may be reduced.

  The weight average molecular weight of the acrylic polymer (A) is important from 80 to 2 million, more preferably from 80 to 1.5 million. When the weight average molecular weight is less than 800,000, the cohesive force is insufficient, and thus the amount of the crosslinking agent used is increased, whereby the adhesive strength is lowered. Therefore, there is a risk of floating or peeling when the uneven surface of the vehicle is applied. On the other hand, when the weight average molecular weight exceeds 2,000,000, the viscosity of the pressure-sensitive adhesive increases, and the coating suitability may decrease.

  The acrylic polymer (A) can be polymerized by solution polymerization, bulk polymerization, emulsion polymerization, or the like. In the present invention, however, solution polymerization is required from the viewpoint of controlling physical properties. As an organic solvent used for polymerization, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, or the like is used. These polymerization solvents may be used as a mixture of two or more.

  Examples of the polymerization initiator used for polymerization include benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroxybenzoate, t-butyl peroxyneodecanoate, t- Organic peroxide polymerization initiators such as butyl peroxy 2-ethylhexanoate; azo polymerizations such as 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobiscyclohexanecarbonitrile Although radical polymerization initiators, such as an initiator, are mentioned, it is not specifically limited. Only one kind of these polymerization initiators may be used, or two or more kinds may be appropriately mixed and used. What is necessary is just to set the usage-amount of a polymerization initiator according to a composition, reaction conditions, etc. of the monomer with which it superposes | polymerizes, and it does not specifically limit.

Furthermore, a chain transfer agent can also be used when the acrylic polymer (A) is polymerized.
Examples of the chain transfer agent include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan; thioglycolic acid esters such as octyl thioglycolate, nonyl thioglycolate, and 2-ethylhexyl thioglycolate; , 4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, and the like. In particular, when thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, and 1-methyl-4-isopropylidene-1-cyclohexene are used, the resulting copolymer has a low odor. preferable. In addition, when using a chain transfer agent, it is used in about 0.001-3 weight part with respect to a total of 100 weight part of the monomer to superpose | polymerize. Moreover, a polymerization reaction is normally performed over 2-8 hours on 40-100 degreeC temperature conditions.

  It is important that the acrylic polymer (B) used in the present invention is a copolymer obtained by reacting at least a methacrylic acid alkyl ester having an alkyl chain having 2 to 6 carbon atoms. It is preferable to use a methacrylic acid alkyl ester having a linear alkyl chain because there is little decrease in adhesion to the adherend even in a low temperature environment. On the other hand, even if it is a methacrylic acid alkyl ester having a linear alkyl chain, a monomer having a high Tg of a homopolymer such as methyl methacrylate, a monomer having a cyclic structure such as cyclohexyl methacrylate, styrene, etc. Aromatic monomers are not preferred because the viscosity of the resulting resin solution is high and the polymerization conversion tends to be low.

  For example, ethyl methacrylate, isopropyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl acrylate, t-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, methacrylic acid Examples include n-hexyl and isohexyl methacrylate. These may use only 1 type or may use multiple types together.

  It is important that the various monomers described above are copolymerized so that the glass transition temperature (Tg) of the acrylic polymer (B) is −10 ° C. or higher and lower than 40 ° C., preferably −5 ° C. or higher, 40 ° C. Is less than. When Tg is 40 ° C. or higher, the wettability of the formed pressure-sensitive adhesive layer is reduced, and the adhesive strength to olefins such as PP is reduced.

  Furthermore, in the present invention, the acrylic polymer (B) preferably has a carboxyl group and / or an amino group. For that purpose, a carboxyl group-containing monomer or an amino group-containing monomer can be used. The total of carboxyl group-containing monomers and amino group-containing monomers is preferably 0.1 to 10% by weight, and more preferably 0.3 to 5% by weight. It is also preferable to use an amide group-containing monomer.

Examples of the amino group-containing monomer include N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropyl acrylamide, and the like. Of these, N, N-dimethylaminoethyl methacrylate is preferred.
Examples of the amide group-containing monomer include N, N-dimethylacrylamide, acryloylmorpholine, Ni-propylacrylamide, and N, N-diethylacrylamide.

  In the present invention, the weight average molecular weight of the acrylic polymer (B) is preferably 1 to 100,000, more preferably 1 to 80,000. When the weight average molecular weight exceeds 100,000, the wettability of the pressure-sensitive adhesive layer is reduced, and the adhesive force to olefins such as PP is reduced. In addition, when the uneven surface is applied, the stress relaxation property is also lowered, and there is a possibility that floating or peeling occurs.

  As a method for producing the acrylic polymer (B), it can be produced by the same method as the acrylic polymer (A) described above.

  In the present invention, it is important that the acrylic polymer (A) and the acrylic polymer (B) are contained in a weight ratio of 50/50 to 95/5, preferably 60/40 to 90/10. When the ratio of the acrylic polymer (B) is more than 50, the adhesive strength is reduced because a large amount of a crosslinking agent is used to compensate for the insufficient cohesive force. For this reason, when the uneven surface is applied, floating or peeling occurs. On the other hand, if it is less than 5% by weight, not only the adhesive strength to olefins such as PP will be reduced, but also the stress relaxation property when it is applied to the uneven surface will be lowered, and floating and peeling will occur.

  In the present invention, the acrylic polymer (A) and the acrylic polymer (B) can be obtained by various methods. For example, the acrylic polymer (A) and the acrylic polymer (B) can be produced separately and mixed together, or after the acrylic polymer (A) is produced, Acrylic polymer (B) can also be obtained by polymerizing monomers in the presence of a polymer.

The copolymer in that case has a high molecular weight component (A) and a low molecular weight component (B), and shows two peaks in the GPC emission curve, with the minimum value (valley) on the emission curve as a boundary. Then, the weight average molecular weight of the high molecular weight component (A) obtained by dividing the two at the trough is acrylic polymer (A), and the weight average molecular weight of the low molecular weight component (B) is acrylic polymer (B). Further, the area ratio of the high molecular weight component (A) / the low molecular weight component (B) divided at the valley is defined as the weight ratio of the acrylic polymer (A) and the acrylic polymer (B).
Further, the glass transition temperature (Tg) of the acrylic polymer (A) and the acrylic polymer (B) was measured by measuring the amount of monomer remaining by gas chromatography after the acrylic polymer (A) was produced. It is important that copolymerization is performed so that the glass transition temperature (Tg) of the polymer (B) is -10 ° C or higher and lower than 40 ° C.

  The crosslinking agent (C) constituting the pressure-sensitive adhesive of the present invention has a functional group capable of reacting with at least one of a carboxyl group or a hydroxyl group of the acrylic polymer (A). Examples of such a crosslinking agent (C) include isocyanate compounds, epoxy compounds, metal chelate compounds, aziridine compounds, amine compounds, carbodiimide compounds, oxazoline compounds, and melamine compounds. By using the crosslinking agent, the cohesive force of the pressure-sensitive adhesive layer can be further improved. Only one kind of these crosslinking agents may be used, or two or more kinds may be used in combination.

Here, examples of the isocyanate compound include aromatic polyisocyanate, aliphatic polyisocyanate, araliphatic polyisocyanate, and alicyclic polyisocyanate.
Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-triisocyanate. Range isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 " -Triphenylmethane triisocyanate etc. can be mentioned.
Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate. 2,4,4-trimethylhexamethylene diisocyanate and the like.
Examples of the araliphatic polyisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene, , 4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and the like.
Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- Examples include 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane and the like.

The polyisocyanate can be modified to be used as a multimer such as a trimethylolpropane adduct or an isocyanurate trimer.
Moreover, polyphenylmethane polyisocyanate (PAPI), naphthylene diisocyanate, and these polyisocyanate modified products can be used. As the polyisocyanate-modified product, a carbodiimide group, a uretdione group, a uretoimine group, a burette group reacted with water, a group of isocyanurate groups, or a modified product having two or more of these groups can be used. A reaction product of a polyol and a diisocyanate can also be used as a polyisocyanate.
These polyisocyanate compounds include 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), xylylene diisocyanate, 4,4′-methylenebis. From the viewpoint of weather resistance, it is particularly preferable to use a non-yellowing or hardly yellowing polyisocyanate compound such as (cyclohexyl isocyanate) (hydrogenated MDI).

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

  Examples of metal chelate compounds include chelate compounds composed of acetylacetone and acetone esters of divalent or higher metals such as aluminum, copper, iron, tin, zinc, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Can be mentioned.

  Examples of the aziridine compound include trimethylolpropane-tri-β-aziridinylpropionate, bisisophthaloyl-1- (2-methylaziridine), and the like.

  As the amine compound, any polyamine having two or more primary amino groups can be used without particular limitation. A polyamine having two or more primary amino groups that are not directly bonded to the aromatic ring, that is, the primary amino group is directly bonded to an aliphatic functional group or an alicyclic functional group because of its excellent curing speed. Aliphatic polyamines are preferred. The aliphatic polyamine may contain an aromatic ring in its skeleton as long as the aromatic ring is not directly bonded to the primary amino group.

Aliphatic polyamines include 2,5-dimethyl-2,5-hexamethylenediamine, mensendiamine, 1,4-bis (2-amino-2-methylpropyl) piperazine, and propylene branched carbon at both ends of the molecule. Polypropylene glycol to which an amino group is bonded [a diamine having a propylene skeleton, such as “Jefamine D230” and “Jefamine D400” manufactured by Sun Techno Chemical Co., Ltd.], and a triamine having a propylene skeleton, such as “Jeffamine T403”. ], Ethylenediamine, propylenediamine, butylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, trimethylhexamethylenediamine, N-aminoethylpiperazine, 1,2-diaminopropane, iminobispropyl Amines such as amine, methyliminobispropylamine, H ₂ N (CH ₂ CH ₂ O) ₂ (CH ₂ ) ₂ NH ₂ [“Jefamine EDR148” (diamine with ethylene glycol skeleton) manufactured by Sun Techno Chemical Co.] Polyether skeleton diamine, 1,5-diamino-2-methylpentane ("MPMD" manufactured by DuPont Japan), metaxylylenediamine (MXDA), polyamidoamine (Sanwa Chemical) "X2000"), isophoronediamine, 1,3-bisaminomethylcyclohexane ("1,3BAC" manufactured by Mitsubishi Gas Chemical Company), 1-cyclohexylamino-3-aminopropane, 3-aminomethyl-3,3,5 -Trimethyl-cyclohexylamine, dimethyleneamine having a norbornane skeleton (“NBDA” manufactured by Mitsui Chemicals) and the like.
Among these, since the curing rate is particularly high, 1,3-bisaminomethylcyclohexane, dimethyleneamine having a norbornane skeleton, metaxylylenediamine, H ₂ N (CH ₂ CH ₂ O) ₂ (CH ₂ ) ₂ NH ₂ (ethylene glycol skeleton diamine), propylene skeleton diamine, propylene skeleton triamine, and polyamidoamine (trade name: X2000).
Ketimines, which are the reaction products of these polyamines and ketones, are also included in the amine compounds, and from the viewpoints of stability, reactivity adjustment and overcoatability, acetophenone or propiophenone and 1,3-bisaminomethylcyclohexane Obtained from acetophenone or propiophenone and dimethyleneamine (NBDA) having a norbornane skeleton; obtained from acetophenone or propiophenone and metaxylylenediamine; acetophenone or propiophenone; Those obtained from Jeffamine EDR148, Jeffamine D230 and Jeffamine D400, which are diamines having an ethylene glycol skeleton or propylene skeleton, or Jeffamine T403, which is a triamine having a propylene skeleton, etc. It is below.

As the carbodiimide compound, a compound having two or more carbodiimide groups (—N═C═N—) in the molecule is preferably used, and known polycarbodiimides can be used.
As the carbodiimide compound, high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst can also be used.
Examples of such compounds include those obtained by decarboxylation condensation reaction of the following diisocyanates. As the diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-di′phenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′- Diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4, One kind of 4′-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, or a mixture thereof can be used. As the carbodiimidization catalyst, 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl- Phosphorene oxides such as 2-phospholene-1-oxide or their 3-phospholene isomers can be used.

  As the oxazoline compound, a compound having two or more oxazoline groups in the molecule is preferably used. Specifically, 2′-methylenebis (2-oxazoline), 2,2′-ethylenebis (2-oxazoline), 2 , 2′-ethylenebis (4-methyl-2-oxazoline), 2,2′-propylenebis (2-oxazoline), 2,2′-tetramethylenebis (2-oxazoline), 2,2′-hexamethylene Bis (2-oxazoline), 2,2'-octamethylenebis (2-oxazoline), 2,2'-p-phenylenebis (2-oxazoline), 2,2'-p-phenylenebis (4,4 ' -Dimethyl-2-oxazoline), 2,2'-p-phenylenebis (4-methyl-2-oxazoline), 2,2'-p-phenylenebis (4-phenyl- -Oxazoline), 2,2'-m-phenylenebis (2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline), 2,2'-m-phenylenebis (4 4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4-phenylenebis-2-oxazoline), 2,2'-o-phenylenebis (2-oxazoline), 2,2'- o-phenylenebis (4-methyl-2-oxazoline), 2,2′-bis (2-oxazoline), 2,2′-bis (4-methyl-2-oxazoline), 2,2′-bis (4 -Ethyl-2-oxazoline), 2,2′-bis (4-phenyl-2-oxazoline) and the like. Alternatively, it may be a copolymer of vinyl compounds such as 2-isopropenyl-2-oxazoline and 2-isopropenyl-4,4-dimethyl-2-oxazoline, and other monomers copolymerizable therewith.

  The melamine compound is a compound having a triazine ring in the molecule, and examples thereof include melamine, benzoguanamine, cyclohexanecarboguanamine, methylguanamine, vinylguanamine, hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine and the like. These low-condensates, alkyl etherified formaldehyde resins and aminoplast resins may also be used.

  The amount of the crosslinking agent (C) may be determined in consideration of the physical properties of the adhesive, and is not particularly limited. However, by adjusting the amount of the crosslinking agent, the crosslinking density of the adhesive layer in the adhesive sheet can be adjusted. It is necessary to optimize. As a usage-amount of a crosslinking agent (C), 0.0001-10 weight part is preferable with respect to a total of 100 weight part of an acrylic polymer (A) and an acrylic polymer (B), More preferably, 0.001- 1 part by weight. If the usage-amount of a crosslinking agent (C) is less than 0.0001 weight part, there exists a possibility that adhesive force may remain at the time of peeling because cohesion force is low. On the other hand, when the amount of the crosslinking agent (C) used exceeds 10 parts by weight, the elasticity of the pressure-sensitive adhesive layer becomes high, tackiness is reduced, and the adhesive strength is lowered, so that it floats when the uneven surface of the vehicle is applied. There is a risk of peeling. Will occur. In addition, the addition method which adds the crosslinking agent (C) which comprises an adhesive is not specifically limited.

  Further, the pressure-sensitive adhesive of the present invention is a known tackifier resin, silane coupling agent, weathering stabilizer, ultraviolet absorber, heat ray absorbent, plasticizer, softening material, as long as the object of the present invention is not impaired. Various additive components such as dyes, pigments and inorganic fillers can be contained.

  Examples of the tackifier include terpene resin, aliphatic petroleum resin, aromatic petroleum resin, coumarone-indene resin, phenol resin, terpene-phenol resin, rosin derivative (rosin, polymerized rosin, hydrogenated rosin and glycerin thereof. All existing ones such as esters with pentaerythritol, resin acid dimers, etc.) can be used. As the plasticizer, known materials such as phthalates and phosphates can be used.

Next, the decorative sheet of the present invention will be described.
The decorative sheet of the present invention is obtained by forming a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive of the present invention on at least one surface of a sheet-like substrate.
Accordingly, the pressure-sensitive adhesive sheet of the present invention has the following aspects.
A so-called single-sided pressure-sensitive adhesive sheet in which a sheet-like substrate / pressure-sensitive adhesive layer / release sheet is sequentially laminated.
A so-called double-sided pressure-sensitive adhesive sheet in which a release sheet / pressure-sensitive adhesive layer / sheet-like substrate / pressure-sensitive adhesive layer / release sheet is sequentially laminated.

Examples of the sheet-like substrate constituting the decorative sheet of the present invention include, for example, polyolefin resins such as polyethylene, polyester resins such as polyethylene terephthalate, polycarbonate resins, vinyl chloride resins, vinyl acetate resins, acrylic resins, Plastic film made of synthetic resin such as urethane resin, polyimide resin, fluororesin, plastic such as cellophane; paper such as kraft paper, Japanese paper; rubber sheet made of natural rubber, butyl rubber, etc .; polyurethane, polychloroprene rubber, etc. Examples include foam sheets obtained by foaming; metal foils such as aluminum foil and copper foil; and composites thereof. Moreover, surface treatments, such as a corona treatment, may be given to the single side | surface or both surfaces.
Furthermore, as the sheet-like base material, a colored sheet base material containing a colorant such as a pigment or a dye in the above-mentioned various sheets, or a color in which a colored layer is formed on the base material surface by printing such as a screen method or an ink jet method It is preferable to use a sheet substrate. Furthermore, the sheet-like substrate may be a single layer or a multi-layer structure as long as it can function as a decoration.
Moreover, when forming a colored layer by printing on a sheet | seat base material, you may print on a sheet | seat base material before the adhesive process mentioned later, and you may print on the adhesive sheet obtained after an adhesive process.

The release sheet is also referred to as a separator. Examples of such a release sheet include glassine paper, kraft paper, clay-coated paper, paper laminated with a film such as polyethylene, and resins such as polyvinyl alcohol and acrylate copolymer. And the like obtained by applying a release resin such as a fluorine resin or a silicone resin to a paper or the like coated with polyester or a synthetic resin film such as polyester or polypropylene. It is not particularly limited.
Moreover, what is uneven | corrugated processed on the surface of a peeling sheet can also be used.

  The decorative sheet of the present invention can be obtained by various methods. For example, apply and dry the adhesive on one side of the sheet-like base material, stack the release sheet on the surface of the formed adhesive layer, or apply and dry the adhesive on one side of the release sheet, It can be obtained by stacking a sheet-like substrate on the surface of the formed pressure-sensitive adhesive layer.

The application device used when applying the adhesive to various sheet-like substrates is a commonly used application device and is not particularly limited. For example, a roll knife coater, a die coater, a roll coater, a bar Examples include coaters, gravure roll coaters, reverse roll coaters, dipping, blade coaters and the like.
Moreover, it is preferable that drying conditions are the conditions which the solvent of the adhesive for decorative sheets dries and removes at the time of drying, and also carries out a crosslinking reaction. For example, 60 to 120 ° C. and about 1 to 5 minutes are preferable, but not limited thereto. After drying, aging can be performed with the pressure-sensitive adhesive layer sandwiched between sheet-like substrates, and the crosslinking reaction can be further advanced.
In the pressure-sensitive adhesive sheet of the present invention, the thickness of the pressure-sensitive adhesive layer after drying is preferably 1 to 200 μm, and more preferably 10 to 50 μm.

  The adherend material to which the pressure-sensitive adhesive sheet of the present invention is attached may be any metal, synthetic resin, stone, wood, glass, fiber product, paper, lacquer product, leather, or the like. The surface may be flat or uneven. For example, in addition to an advertising tower, a signboard, and a vehicle, a ship, a wall surface of a building, a ceiling, a window, and the like can be given. Specifically, it can also be used for corrugated plates with irregularities used for truck bed parts, commercial vehicles and passenger cars using unpainted PP bumpers, and vehicles such as railway vehicles. In the present application, a vehicle means a wide-range moving body having wheels and an endless track such as a bicycle, a car including a so-called bus / truck, a construction machine such as a bulldozer, a railway vehicle, and an aircraft.

  Next, although an example of the present invention is shown and explained in detail, the present invention is not limited by these. In the examples, “part” means “part by weight” and “%” means “% by weight”.

(Production Example 1)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube (hereinafter simply referred to as “
"Reaction vessel". ) 70 parts of n-butyl acrylate, 20 parts of methyl acrylate, 4 parts of 2-ethylhexyl acrylate, 6 parts of acrylic acid, 72 parts of ethyl acetate, 0.13 of 2,2′-azobis (2-methylbutyronitrile) After replacing the air in the reaction vessel with nitrogen gas, the reaction solution was reacted at reflux temperature for 8 hours in a nitrogen atmosphere with stirring. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content concentration of about 30% and a weight average molecular weight Mw of 910,000.

(Production Examples 2 to 5)
Except for adjusting the amount of ethyl acetate, a solution of an acrylic copolymer having a weight average molecular weight Mw of 1,050,148, 186,000 and 580,000 was obtained in the same manner as in Production Example 1.

(Production Example 6)
An acrylic copolymer solution having a weight average molecular weight Mw of 920,000 was obtained in the same manner as in Production Example 1 except that the monomer composition was changed to 72 parts of n-butyl acrylate, 20 parts of ethyl acrylate, and 8 parts of acrylic acid.

(Production Example 7)
The monomer composition was changed to 75 parts of n-butyl acrylate, 5.9 parts of 2-ethylhexyl acrylate, 20 parts of ethyl acrylate, 8 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and 15 parts of iso-butyl methacrylate. Except for the above, a solution of an acrylic copolymer having a weight average molecular weight Mw of 940,000 was obtained in the same manner as in Production Example 1.

(Production Example 8)
100 parts of toluene was charged in a reaction vessel, and 60 parts of n-hexyl methacrylate, 39 parts of ethyl methacrylate, 1 part of acrylic acid, and 2,2′-azobis (2-methylbutyronitrile) were charged in a dropping device. After the air in the reaction vessel was replaced with nitrogen gas, the reaction solution was dropped in a nitrogen atmosphere with stirring for 1 hour, and the reaction solution was reacted at reflux temperature for 8 hours. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content concentration of about 30% and a weight average molecular weight Mw of 30,000.

(Production Examples 9 to 11)
Except for adjusting the amount of 2,2′-azobis (2-methylbutyronitrile) and the reaction temperature, an acrylic copolymer having a weight average molecular weight Mw of 50,000, 90,000 and 150,000 was prepared in the same manner as in Production Example 8. A solution was obtained.

(Production Example 12)
A solution of an acrylic copolymer having a weight average molecular weight Mw of 30,000 was obtained in the same manner as in Production Example 8, except that the monomer composition was changed to 99 parts of n-hexyl methacrylate and 1 part of acrylic acid.

(Production Example 13)
A solution of an acrylic copolymer having a weight average molecular weight Mw of 30,000, similar to Production Example 8, except that the monomer composition was changed to 64 parts of ethyl methacrylate, 35 parts of n-hexyl methacrylate, and 1 part of acrylic acid. Got.

(Production Example 14)
A solution of an acrylic copolymer having a weight average molecular weight Mw of 30,000, similar to Production Example 8, except that the monomer composition was changed to 64 parts of methyl methacrylate, 35 parts of n-hexyl methacrylate and 1 part of acrylic acid. Got.

(Production Example 15)
An acrylic copolymer solution having a weight average molecular weight Mw of 30,000 was obtained in the same manner as in Production Example 8, except that the monomer composition was changed to 40 parts of iso-butyl methacrylate and 60 parts of n-hexyl methacrylate.

(Production Example 16)
A solution of an acrylic copolymer having a weight average molecular weight Mw of 50,000 was prepared in the same manner as in Production Example 8, except that the monomer composition was changed to 95 parts of n-butyl methacrylate and 5 parts of N, N-dimethylaminoethyl methacrylate. Obtained.

(Production Example 17)
In a reaction vessel, 59.2 parts of n-butyl acrylate, 16 parts of methyl acrylate, 4.8 parts of acrylic acid, 94 parts of ethyl acetate, 16 parts of acetone, 2,2′-azobisisobutyronitrile, 0.012 part The air in the reaction vessel was replaced with nitrogen gas. Thereafter, this reaction solution was reacted at reflux temperature for 12 hours while stirring under a nitrogen atmosphere to obtain a mixed solution of a copolymer having a weight average molecular weight of 1,20,000 and a monomer. In addition, the value of said weight average molecular weight is a value including the detection limit of the GPC apparatus mentioned later, and is a value including an unreacted monomer. As a result of analyzing the obtained liquid mixture by a normal analysis method using gas chromatography, 8% of n-butyl acrylate remained as a monomer.

  Next, 19.0 parts of ethyl methacrylate, N, N-dimethylaminoethyl methacrylate, 1.0 part, 49 parts of ethyl acetate, 13 parts of methyl ethyl ketone and 0.07 part of AIBN were added, and the reaction was further continued for 6 hours. After completion, the mixture was diluted with ethyl acetate to obtain an acrylic polymer solution having a nonvolatile content concentration of 30%.

  The acrylic polymer solution has a high molecular weight component (A) and a low molecular weight component (B), and shows two peaks in the GPC discharge curve with the minimum value (valley) on the discharge curve as a boundary. The weight average molecular weight of the high molecular weight component (A) obtained by dividing at the valley portion is 1,120,000, and the weight average molecular weight of the low molecular weight component (B) is 40,000, and divided by the valley portion (A) / ( The area ratio of B) was 81/19. In Table 1, the left column of Production Example 17 shows the monomer composition of the high molecular weight component (A), and the right column shows the composition of the monomer for the low molecular weight component (B).

The types of copolymerizable monomers constituting the copolymer (a) in Table 1 are indicated by the following abbreviations.
BA: butyl acrylate (Tg of homopolymer = −54 ° C.)
iBMA: iso-butyl methacrylate (Tg of homopolymer = 67 ° C.)
nBMA: butyl methacrylate (Tg of homopolymer = 20 ° C.)
EA: ethyl acrylate (homopolymer Tg = −22 ° C.)
MA: methyl acrylate (Tg of homopolymer = 8 ° C.)
MMA: Methyl methacrylate (homopolymer Tg = 105 ° C.)
2EHA: 2-ethylhexyl acrylate (homopolymer Tg = −85 ° C.)
VAC: vinyl acetate (homopolymer Tg = 29 ° C.)
AA: Acrylic acid (Tg of homopolymer = 106 ° C.)
HEA: 2-hydroxyethyl acrylate (homopolymer Tg = −15 ° C.)
Light ester DM (Kyoeisha Chemical Co., Ltd .: N, N-dimethylaminoethyl methacrylate (homopolymer Tg = 18 ° C.))

(Weight average molecular weight)
It is a weight average molecular weight in terms of polystyrene determined by GPC measurement, and the measurement conditions are as follows.
Equipment: HCL8820GPC manufactured by Tosoh Corporation
Column: Three TSKgel GMHXLs manufactured by Tosoh Corporation are connected and used.
Solvent: Tetrahydrofuran Flow rate: 0.5 ml / min
Temperature: 40 ° C
Sample concentration: 0.2 wt%
Sample injection volume: 100 μl

〔Glass-transition temperature〕
The Tg of the copolymer was calculated from the formula “FOX” below based on the homopolymer Tg.
1 / Tg = [(W1 / Tg1) + (W2 / Tg2) + ... + (Wn / Tgn)]
/ 100 (Here, the temperature is an absolute temperature.)
Wn:% by weight of monomer n
Tgn: It can be determined from the glass transition temperature of a homopolymer composed of monomer n.

Example 1
75 parts by weight of the copolymer solution obtained in Production Example 1, 25 parts by weight of the copolymer solution obtained in Production Example 9, and N, N, N ′, N′-tetraglycidyl-m-xylyl as an epoxy crosslinking agent 0.021 part of range amine was added and stirred uniformly to obtain an adhesive.
The obtained pressure-sensitive adhesive was applied onto a commercially available peelable sheet so that the dry coating thickness was 30 μm, and dried at 100 ° C. for 2 minutes. The pressure-sensitive adhesive layer surface and a vinyl chloride resin sheet (thickness 50 μm) Were stuck together to produce an adhesive sheet.

(Example 2)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that 65 parts by weight of the copolymer solution obtained in Production Example 2 and 35 parts by weight of the copolymer solution obtained in Production Example 9 were used.

(Example 3)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that 75 parts by weight of the copolymer solution obtained in Production Example 2 and 25 parts by weight of the copolymer solution obtained in Production Example 9 were used.
Example 4
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that 85 parts by weight of the copolymer solution obtained in Production Example 2 and 15 parts by weight of the copolymer solution obtained in Production Example 9 were used.

(Example 5)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the copolymer solution obtained in Production Example 3 was used instead of the copolymer solution obtained in Production Example 1.

(Example 6)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the copolymer solution obtained in Production Example 4 was used instead of the copolymer solution obtained in Production Example 1.

(Example 7)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the copolymer solution obtained in Production Example 6 was used instead of the copolymer solution obtained in Production Example 1.

(Example 8)
75 parts by weight of the copolymer solution obtained in Production Example 7 and 25 parts by weight of the copolymer solution obtained in Production Example 9, an isocyanate crosslinking agent (“Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd., non-volatile content concentration 75% ) 0.75 part was added and stirred uniformly to obtain an adhesive solution.
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 using the obtained pressure-sensitive adhesive solution.

Example 9
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3 except that the copolymer solution obtained in Production Example 8 was used in place of the copolymer solution obtained in Production Example 9.

(Example 10)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3 except that the copolymer solution obtained in Production Example 10 was used instead of the copolymer solution obtained in Production Example 9.

(Example 11)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3, except that the copolymer solution obtained in Production Example 12 was used instead of the copolymer solution obtained in Production Example 9.

(Example 12)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3 except that the copolymer solution obtained in Production Example 13 was used instead of the copolymer solution obtained in Production Example 9.

(Example 13)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3 except that the copolymer solution obtained in Production Example 15 was used instead of the copolymer solution obtained in Production Example 9.

(Example 14)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3 except that the copolymer solution obtained in Production Example 16 was used instead of the copolymer solution obtained in Production Example 9.
(Example 15)
100 parts by weight of the copolymer solution obtained in Production Example 17 and 0.021 part of N, N, N ′, N′-tetraglycidyl-m-xylylenediamine as an epoxy crosslinking agent were added and stirred uniformly. An adhesive solution was obtained.
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 using the obtained pressure-sensitive adhesive solution.

(Comparative Example 1)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that 30 parts by weight of the copolymer solution obtained in Production Example 2 and 70 parts by weight of the copolymer solution obtained in Production Example 9 were used.

(Comparative Example 2)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that 100 parts by weight of the copolymer solution obtained in Production Example 2 was used.
(Comparative Example 3)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that 75 parts by weight of the copolymer solution obtained in Production Example 5 and 25 parts by weight of the copolymer solution obtained in Production Example 9 were used.
(Comparative Example 4)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that 75 parts by weight of the copolymer solution obtained in Production Example 2 and 25 parts by weight of the copolymer solution obtained in Production Example 11 were used.
(Comparative Example 5)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that 75 parts by weight of the copolymer solution obtained in Production Example 2 and 25 parts by weight of the copolymer solution obtained in Production Example 14 were used.

[Measurement of physical properties of adhesive sheet]
About the adhesive sheet obtained by the Example and the comparative example, after making it pass for 7 days in the atmosphere of 23 degreeC-50% RH and aging an adhesive layer, the test shown below was done. The results are shown in Table 1.

[SUS adhesive strength]
This was performed according to JIS Z 0237. A test piece having a width of 25 mm was cut out from each pressure-sensitive adhesive sheet, the separator was peeled off, affixed to a stainless steel plate in an atmosphere of 23 ° C.-50% RH, and reciprocated once with a 2 kg roll to obtain a measurement sample.
Peeling strength when peeled at an angle of 180 ° at a tensile speed of 300 mm / min with a tensile tester after being placed in the same environment for 20 minutes (initial) and 24 hours (permanent), respectively. N / inch) was measured.

[PP adhesive strength]
This was performed according to JIS Z 0237. A 25 mm wide test piece is cut out from each adhesive sheet, the separator is peeled off, affixed to a polypropylene plate in a 10 ° C.-50% RH atmosphere and a 23 ° C.-50% RH atmosphere, and reciprocated once with a 2 kg roll. Thus, a measurement sample was obtained.
Measure the peel strength (N / inch) when left at the same environment for 24 hours or more (permanently) and then peel off at a 180 ° angle with a tensile tester at a tensile speed of 300 mm / min. did.

[PP curved surface holding force]
A test piece having a width of 25 mm was cut out from each pressure-sensitive adhesive sheet, the separator was peeled off, and after being attached to a polypropylene rod having a diameter of 100 mm, a measurement sample was obtained. And after leaving for 1 week in the environment of 60 degreeC-80% RH, it evaluated visually.
The evaluation criteria are shown below.
◎ ・ ・ ・ No lifting or peeling of the adhesive sheet.
○ ・ ・ ・ Slight float, but no problem in practical use.
X: Floating and peeling.

[Constant load peel test]
Each adhesive sheet is cut into a strip of 25 mm width and 200 mm length, the separator is peeled off, and a 25 mm width x 180 mm portion is repeated at intervals of 45 mm with a 10 mm high bulge and a 25 mm flat portion repeatedly. A sample to be measured was obtained by pasting on a melamine-coated plate with a convex portion and then pressure bonding.
The obtained measurement sample is allowed to stand in an atmosphere of 23 ° C.-50% RH for 24 hours, and the melamine coated plate with the convex portion is kept horizontal so that the pasting surface is on the lower side. A weight of 100 g was suspended at the end of the sheet, left for 24 hours, and then visually evaluated.
The evaluation criteria are shown below.
◎ ・ ・ ・ No peeling of adhesive sheet.
○ The weight has not dropped after 24 hours.
X: The weight dropped within 24 hours.

[Removability]
Cut each adhesive sheet into a strip with a width of 25 mm and a length of 100 mm, peel off the separator, paste the 25 mm wide x 80 mm long part to a flat melamine coating plate, and reciprocate it with a 2 kg roll for pressure bonding. A measurement sample was obtained.
The obtained measurement sample was allowed to stand for 1000 hours in an atmosphere of 60 ° C. to 80% RH, and then the pressure-sensitive adhesive sheet was peeled off, and the surface of the melamine coated plate was visually evaluated.
The evaluation criteria are shown below.
◎ ・ ・ ・ No glue residue, good re-peelability ○ ・ ・ ・ Spot-like glue residue, but good re-peelability × ・ ・ ・ There is glue residue, poor re-peelability

The above evaluation results are shown in Table 2.

From the results in Table 2, the decorative sheet using the decorative sheet adhesive of the present invention has good SUS adhesive strength, PP adhesiveness, constant load peeling, and removability.
In Comparative Example 1, when the same acrylic polymer (A) and acrylic polymer (B) as in Examples 2 to 4 were used, but the weight ratio of the acrylic polymer (B) was too large, Not only the SUS adhesive strength is reduced, but also PP adhesiveness, constant load property, and removability are reduced. Moreover, PP adhesiveness falls in the comparative example 2 which does not contain an acrylic polymer (B). Similarly, when the weight average molecular weight of the acrylic polymer (B) is too large or the glass transition temperature is too high, the PP adhesiveness is lowered. In Comparative Example 3, when the weight average molecular weight of the acrylic polymer (A) is too small, the constant load peeling and the removability are also lowered.
When used as a decorative sheet, the pressure-sensitive adhesive for decorative sheet of the present invention has good followability to olefinic adherends and uneven surfaces, and does not float or peel off. It has an excellent feature that it can be peeled off without it.

Claims (4)

Acrylic polymer (A) obtained by solution polymerization having a glass transition temperature of −70 to −10 ° C. and a weight average molecular weight of 800,000 to 2,000,000, a glass transition temperature of −10 ° C. to less than 40 ° C., and a weight average molecular weight of 1 A pressure-sensitive adhesive containing an acrylic polymer (B) formed by solution polymerization of 100,000 or less and a crosslinking agent (C),
The acrylic polymer (B) is a copolymer obtained by reacting at least a methacrylic acid alkyl ester having an alkyl chain having 2 to 6 carbon atoms,
Furthermore, the pressure-sensitive adhesive for decorative sheets, wherein the acrylic polymer (A) and the acrylic polymer (B) are used in a weight ratio of 50/50 to 95/5. The pressure-sensitive adhesive for decorative sheets according to claim 1, wherein the acrylic polymer (B) further contains a carboxyl group and / or an amino group.   A decorative sheet formed by forming a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for decorative sheets according to claim 1 or 2 on a sheet-like substrate.   A vehicle comprising the decorative sheet according to claim 3.