JP2020019928A - Pressure sensitive adhesive and pressure sensitive adhesive sheet - Google Patents

Abstract

To provide a pressure sensitive adhesive which has removability while exhibiting good adhesion to an oily adherend, and is also excellent in tack and in water resistance.SOLUTION: The pressure sensitive adhesive comprises an acrylic copolymer (A), an isocyanate curative (B), a tackifier (C), and a removability-enhancing agent (D). The acrylic copolymer (A) comprises a carboxyl group-containing monomer (a1) as a monomer unit forming the copolymer. The content of the isocyanate curative (B) is from 0.3 pt.mass to 10 pts.mass inclusive based on 100 pts.mass of the acrylic copolymer (A). The tackifier (C) comprises a terpene resin and/or petroleum resin. The removability-enhancing agent (D) includes a removability-enhancing agent having a molecular mass from 250 to 1000 inclusive.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

  There are various resin-based adhesives, and among them, acrylic is widely used. Acrylic pressure-sensitive adhesives have the advantage that control of basic pressure-sensitive adhesive properties such as adhesive strength and tackiness is easy by adjusting the monomer composition and compatible additives. Conventionally, there has been a market need to be able to adhere to an oil-adhered adherend, but in recent years there has been an increasing demand for more convenient and more sophisticated performance. Patent Literature 1 discloses a pressure-sensitive adhesive sheet for an adherend surface to which oil has adhered, comprising a specific (meth) acrylic copolymer and a tackifier having a softening point exceeding 115 ° C. Here, although the oil surface adhesive strength is good, there has been a problem that the adhesive strength gradually increases over time, and glue remains when peeled off several weeks later.

JP 2014-095021 A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive that exhibits removability while exhibiting good adhesive strength to an oil-adhered adherend, and is additionally excellent in tack and water resistance.

The present inventors have conducted intensive studies in order to solve the above problems, and as a result, have completed the present invention.
That is, an embodiment of the present invention relates to a pressure-sensitive adhesive containing an acrylic copolymer (A), an isocyanate curing agent (B), a tackifier (C), and a peeling agent (D). The polymer (A) contains a carboxyl group-containing monomer (a1) as a monomer unit constituting the copolymer, and the blending amount of the isocyanate curing agent (B) is 100 parts by mass of the acrylic copolymer (A). 0.3 parts by mass or more and 10 parts by mass or less, the tackifier (C) contains a terpene resin and / or a petroleum resin, and the release agent (D) has a molecular weight of 250 or more and 1000 or less. Adhesives, including certain

  In an embodiment of the present invention, the acrylic copolymer (A) further comprises an alkyl (meth) acrylate (a2) having an alkyl group having 8 to 10 carbon atoms and an alkyl group having 1 to 3 carbon atoms. It is the said adhesive containing the (meth) acrylic acid alkyl ester (a3) which has this.

  An embodiment of the present invention is the above-mentioned pressure-sensitive adhesive, wherein the acrylic copolymer (A) further contains a hydroxyl group-containing monomer (a4).

  In an embodiment of the present invention, the isocyanate curing agent (B) is the pressure-sensitive adhesive having an aromatic ring.

  In an embodiment of the present invention, the terpene resin includes a hydrogenated terpene resin, and the petroleum resin is the pressure-sensitive adhesive including a hydrogenated petroleum resin.

  An embodiment of the present invention is the above-mentioned pressure-sensitive adhesive wherein the solubility of the release-imparting agent (D) in water at 25 ° C. is 10 g / L or less.

  An embodiment of the present invention is the above-mentioned pressure-sensitive adhesive for bonding to an adherend whose surface is partially covered with oil.

  Further, the embodiment of the present invention is characterized in that the alkyl (meth) acrylate (a3) having an alkyl group having 1 to 3 carbon atoms is contained in the monomer constituting the copolymer in an amount of 3% by mass or more and 20% by mass or less. Is the above-mentioned pressure-sensitive adhesive.

  Further, an embodiment of the present invention is a pressure-sensitive adhesive sheet provided with a substrate and a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive.

  An embodiment of the present invention is the above-mentioned pressure-sensitive adhesive sheet for sticking to an adherend whose surface is partially covered with oil.

  The pressure-sensitive adhesive of the present invention has excellent adhesiveness to an oil-adhered adherend, and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive has good removability, tackiness and water resistance.

  Hereinafter, details of the present invention will be described. In the present specification, when “(meth) acryl”, “(meth) acryloyl”, “(meth) acrylic acid”, “(meth) acrylate”, and “(meth) acryloyloxy” are used, Unless otherwise specified, they represent “acryl or methacryl”, “acryloyl or methacryloyl”, “acrylic or methacrylic acid”, “acrylate or methacrylate”, “acryloyloxy or methacryloyloxy”, respectively. "Acrylic copolymer which is a copolymer containing a carboxyl group-containing monomer, an alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms, and an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms “Copolymer (A)” may be abbreviated as “acrylic resin (A)”. Further, “parts” and “%” represent “parts by mass” and “% by mass”, respectively, unless otherwise specified.

The pressure-sensitive adhesive of the present invention is a pressure-sensitive adhesive containing an acrylic copolymer (A) containing the following (a1) as a monomer constituting the copolymer. Further, the following monomers (a2), (a3) and (a4) and other monomers may be contained as monomers constituting the copolymer.
(A1) Carboxyl group-containing monomer (a2) Alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms (a3) Alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms (a4) Hydroxyl-containing monomer

<(A1) Carboxyl group-containing monomer>
In the present invention, (a1) is used as a monomer constituting the acrylic copolymer (A) in order to improve the adhesiveness to the oil-adhered adherend. Here, the carboxyl group-containing monomer means a monomer having a carboxyl group.

Specific examples of (a1) include (meth) acrylic acid, β-carboxyethyl (meth) acrylate, and the like. Among these, (meth) acrylic acid is more preferred.
The content of (a1) in all the monomers constituting the copolymer is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1% or more, and particularly preferably 1.5% or more. . Moreover, 15% or less is preferable, 10% or less is more preferable, 8% or less is further preferable,
Particularly preferred is 5% or less. When the content is within the above range, it becomes easy to achieve both cohesive force and adhesiveness to the oil-adhering surface.

<(A2) Alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms>
The monomer constituting the acrylic copolymer (A) preferably contains (a2). Here, the alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms means that the alkyl group in the alkyl (meth) acrylate has 8 to 10 carbon atoms. By containing (a2), the acrylic copolymer (A) becomes easily compatible with the oil-adhered adherend, and reliable adhesiveness is exhibited. In addition, improvement in tack and water resistance can be expected.

Examples of (a2) include 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isodecyl (meth) acrylate, and the like. Among these, 2-ethylhexyl acrylate is preferred.
The content of (a2) in all the monomers constituting the copolymer is preferably at least 10%, more preferably at least 30%, even more preferably at least 50%. In addition, 98% or less is preferable, 95% or less is more preferable, and 90% or less is further preferable. When the content is within the above range, the adhesiveness to the oil-adhered surface and the water resistance are improved, and the removability is easily imparted.

<(A3) Alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms>
(A3) can be contained as a monomer constituting the acrylic copolymer (A). By containing (a3), when the acrylic copolymer (A) contains a large amount of (a2), deterioration of the removability due to too low a glass transition temperature of the resin can be prevented.

Examples of (a3) include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. Among these, methyl acrylate and ethyl acrylate are preferred.
The content of (a3) in all the monomers constituting the copolymer is preferably 1% or more, more preferably 2% or more, still more preferably 3% or more, and particularly preferably 5% or more. Further, it is preferably at most 40%, more preferably at most 30%, further preferably at most 20%. When it is within the above range, it becomes easy to achieve both adhesion to the oil-adhered surface and tackiness and removability.

<(A4) Hydroxyl group-containing monomer>
The acrylic copolymer (A) preferably contains a hydroxyl group-containing monomer (a4) as a monomer constituting the copolymer. The hydroxyl group-containing monomer means a monomer having a hydroxyl group. By containing (a4), a polymer network is formed by a crosslinking reaction with an isocyanate curing agent, and improvement in adhesiveness and removability can be expected.

As the hydroxyl group-containing monomer (a4), hydroxyalkyl (meth) acrylate is preferred. Specific examples include 2-hydroxyethyl (meth) acrylate, 7-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, and the like. Among these, 2-hydroxyethyl (meth) acrylate is preferred.
The content of (a4) in all the monomers constituting the copolymer is preferably 0.05% or more, more preferably 0.1% or more. Further, it is preferably at most 5%, more preferably at most 3%. When it is within the above range, it becomes easy to achieve both tackiness and removability and tackiness.

<Other monomers>
The acrylic copolymer (A) may contain other monomers other than the above-mentioned monomers (a1) to (a4) as monomers constituting the copolymer. Other monomers include alkyl (meth) acrylate having an alkoxy group, alkyl (meth) acrylate having an amino group, alkyl (meth) acrylate having an amide group, and the like.

As the monomer having an alkoxy group, an alkoxyalkyl (meth) acrylate is preferred. Here, the carbon number of the alkoxy group in the (meth) acrylic acid alkoxyalkyl ester is preferably 1 to 12, more preferably 1 to 4, and even more preferably 1 or 2. Further, the carbon number of the alkylene group bonded to the alkoxy group in the (meth) acrylic acid alkoxyalkyl ester is preferably 1 to 18, more preferably 1 to 8, and preferably 1 to 4. More preferred.
Specific examples of the monomer having an alkoxy group include 2-methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxymethyl (meth) acrylate, and 2-ethoxyethyl (meth) acrylate. , 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, and the like. Among these, 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate are preferred.

  Examples of the monomer having an amino group include a monomer having an unsubstituted amino group and a monomer having a substituted amino group, preferably a monomer having a substituted amino group, and more preferably a monomer having a substituted amino group. (Meth) acrylates having an amino group substituted with an alkyl group, more preferably N-alkylamino (meth) acrylates and (meth) acrylates. ) N, N-dialkylamino acrylate. Here, examples of the substituent in the substituted amino group include an alkyl group, an alkyl group substituted with a hydroxyl group, an alkyl group substituted with a carbonyl group, and the like. 1-4 alkyl groups are more preferred. Specific examples of the monomer having an amino group include aminomethyl (meth) acrylate, N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylic acid N, N-diethylaminoethyl, N, N-dimethylaminopropyl (meth) acrylate and the like can be mentioned. Among these, N, N-dimethylaminoethyl methacrylate is preferred.

  The monomer having an amide group is not particularly limited as long as it has a amide group (—C (＝ O) N—), but a hydrogen atom on a nitrogen atom of (meth) acrylamide is substituted with a substituent. Preferably, the derivative is one or more substituted with an alkyl group which may be possessed. Here, examples of the alkyl group which may have a substituent include an alkyl group, an alkyl group substituted with a hydroxyl group, an alkyl group substituted with a carbonyl group, and the like. Specific examples of the monomer having an amide group include (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, N-vinylacetamide, and N-vinylacetamide. Vinylpyrrolidone, 4-acryloylmorpholine and the like. Among these, diacetone acrylamide is preferred.

  Examples of the alkyl (meth) acrylate other than the above include, for example, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, dodecyl (meth) acrylate, Examples thereof include tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl (meth) acrylate. These can be used alone or in combination of two or more.

The weight average molecular weight of the acrylic resin (A) is preferably 300,000 or more, more preferably 500,000 or more, and still more preferably 800,000 or more. Further, it is preferably 2.5 million or less, more preferably 2 million or less, and still more preferably 1.5 million or less. When the weight average molecular weight is within the above range, it is easy to achieve both tackiness and removability.

The acrylic resin (A) can be produced by a known method, but is preferably produced by solution polymerization. In the solution polymerization, as a solvent used in the polymerization, use an ester solvent such as methyl acetate and ethyl acetate, a ketone solvent such as acetone and methyl ethyl ketone, and a hydrocarbon solvent such as toluene and xylene. Is preferred.

Specifically, a solvent, a monomer, a polymerization initiator, etc., under an inert gas atmosphere such as nitrogen gas,
It is common to heat to a reaction temperature of about 50 to 90 ° C. and carry out a polymerization reaction for 4 to 12 hours.

Examples of the polymerization initiator include an azo initiator and a peroxide initiator. These polymerization initiators are usually used in an amount within a range from 0.01 to 5 parts by mass based on 100 parts by mass of the raw material monomer. During the polymerization reaction, a chain transfer agent, a raw material monomer, and a solvent may be appropriately added.

  Among the above polymerization initiators, examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile) and 1,1′-azobis (cyclohexane 1-carbonitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis ( 2-methylpropionate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2 -Imidazolin-2-yl) propane].

Among the polymerization initiators, examples of the organic peroxide include benzoyl peroxide and t-
Butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, di (2-ethoxyethyl) peroxy dicarbonate, t-butyl peroxy neodecanoate, t- Butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

Under the conditions as described above, the weight average molecular weight of the obtained copolymer is adjusted according to known techniques by adjusting the reaction conditions such as the type and amount of the solvent used, the type and amount of the polymerization initiator, the reaction time, and the reaction temperature. Can be adjusted.

<Isocyanate curing agent (B)>
The isocyanate curing agent (B) is, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, triphenyl Methane triisocyanate, and a diisocyanate such as polymethylene polyphenyl isocyanate and an adduct of a polyol compound such as trimethylolpropane, and a burette thereof, and an isocyanurate thereof, and the above-described diisocyanate, polyether polyol, polyester polyol, Acrylic polyol, polybutadiene polio Compounds having three or more isocyanate groups in the molecule, such as adducts with any of the polyols and polyisoprene polyols; or having two isocyanate groups in the molecule, such as allophanate bodies And the like. Among these, a trimethylolpropane adduct of tolylene diisocyanate and a trimethylolpropane adduct of xylylene diisocyanate are preferable because the adhesive properties can be easily adjusted. The number of isocyanate groups is an average number.

  The compounding amount of the isocyanate curing agent (B) is at least 0.3 part by mass, preferably at least 0.5 part by mass, and more preferably 1 part by mass, based on 100 parts by mass of the acrylic copolymer (A). More preferably, it is the above. Also, it is 10 parts by mass or less, preferably 8 parts by mass or less, more preferably 5 parts by mass or less. When the content is within the above range, it becomes easy to achieve both adhesion to the oil-adhered surface and tackiness and removability.

  In addition, as a curing agent, an epoxy curing agent, aziridine, or a metal chelate can be used as long as the effects of the present invention are not impaired. The curing agents can be used alone or in combination of two or more.

<Tackifier (C)>
The tackifier (C) can be used by any method such as a method used during solution polymerization and a method of blending it with the acrylic copolymer (A). When the tackifier resin is used at the time of solution polymerization, it acts as a chain transfer agent and facilitates adjustment of the molecular weight of the acrylic copolymer (A). Further, by blending it with the acrylic copolymer (A), the adhesive strength to the oil-adhering surface can be raised.

  Examples of the tackifier (C) include a rosin resin, a rosin ester resin, a rosin phenol resin, a terpene resin, a terpene phenol resin, a coumarone resin, a coumarone indene resin, a styrene resin, a xylene resin, a phenol resin, and a petroleum resin. Can be Among these, the pressure-sensitive adhesive of the present invention contains a terpene resin and / or a petroleum resin, because the compatibility with the acrylic copolymer is good and the adhesion performance to the oil-adhering surface can be further improved. Further, the terpene resin more preferably contains a hydrogenated terpene resin, and the petroleum resin preferably contains a hydrogenated petroleum resin.

The softening point of the tackifier (C) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and further preferably 100 ° C. or higher. The upper limit of the softening point is preferably 170 ° C. or lower, more preferably 140 ° C. or lower, and further preferably 115 ° C. or lower. When the softening point of the tackifier (C) is within the above range, it becomes easy to achieve both high adhesion to the oil-adhered surface, removability and tack at a high level. The softening point is a softening temperature measured according to the dry-bulb method specified in JIS K5902.

  The tackifier (C) is preferably contained in an amount of 1 part by mass or more, more preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the acrylic copolymer (A). . Further, the amount is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 20 parts by mass or less. When the content is in the above range, it is easy to achieve both the adhesiveness to the oil-adhered surface and the removability. The tackifier (C) can be used alone or in combination of two or more.

<Release imparting agent (D)>
The release-imparting agent refers to a material capable of imparting easily peelable performance when the pressure-sensitive adhesive sheet is released from the adherend. By blending the release imparting agent with the acrylic copolymer (A), re-peelability can be imparted while maintaining the adhesive force to the oil-adhering surface. The release imparting agent (D) used in the present invention has a molecular weight of 250 or more and 1000 or less. When the molecular weight is within the above range, compatibility with the acrylic copolymer is good, and adhesion to the oil-adhered surface and tackiness and removability are easily compatible.

  The release imparting agent (D) is, for example, a monoester, diester, triester, or an unsaturated fatty acid having 14 to 18 carbon atoms of a monobasic acid or polybasic acid having 1 to 18 carbon atoms and an alcohol having 18 or less carbon atoms. Or an ester of a branched acid and an alcohol having a valency of 4 or less, an ester of a monobasic acid or polybasic acid having 1 to 18 carbon atoms and a polyalkylene glycol, a diester, a triester or a tetraester of a hydroxy acid and a monobasic acid or an alcohol And fatty acid esters and phosphate esters in which unsaturated sites are epoxidized with a peroxide or the like.

  Examples of esters of a monobasic acid or polybasic acid having 1 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms include, for example, isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isopalmitate. Examples include stearyl, isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitate, and triisocetyl trimellitate.

  Examples of the unsaturated fatty acid having 14 to 18 carbon atoms and the branched acid and the alcohol having 4 or less valency constituting the ester of the unsaturated fatty acid having 14 to 18 carbon atoms or the branched acid and the alcohol having 4 or less are as follows. . Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, isostearic acid, and the like. Examples of the tetravalent or lower alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.

  Esters of polyalkylene glycols with monobasic or polybasic acids having 1 to 18 carbon atoms include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and adipic acid Dipolyethylene glycol methyl ether and the like.

  Esters of hydroxy acid and monobasic acid or alcohol include octyldodecyl lactate, diisostearyl malate, methyl 2-hydroxymyristate, 2-ethylhexyl 12-hydroxystearate, ethyl ricinoleate, methyl o-acetyl ricinoleate, o -Butyl acetyl ricinoleate, triethyl citrate, tributyl o-acetyl citrate, tri (2-ethylhexyl) o-acetyl citrate and the like.

  Fatty acid esters in which unsaturated sites are epoxidized with peroxide or the like, for example, epoxidized unsaturated fatty acids having 8 to 18 carbon atoms or epoxidized oils and fats such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized cottonseed oil. An ester compound of a compound and a linear or branched alcohol having 1 to 6 carbon atoms is exemplified.

  Examples of the phosphate ester include an ester compound of phosphorous acid or phosphoric acid and a linear or branched alcohol having 2 to 18 carbon atoms. Among these, tributyl phosphate, 2-ethylhexyl acid phosphate, oleyl acid phosphate, ethylene glycol acid phosphate, and the like are listed because they are excellent in compatibility with the acrylic copolymer (A) and stable in removability after aging. Can be

  The solubility of the release-imparting agent (D) in water at 25 ° C. (in this specification, sometimes simply referred to as “solubility”) is preferably 10 g / L or less, more preferably 1 g / L or less. The water resistance is improved by selecting a release imparting agent having low solubility in water.

  The release imparting agent (D) is preferably contained in an amount of 0.1 part by mass or more, more preferably 1 part by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the acrylic copolymer (A). More preferred. Further, the amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content is in the above range, the removability is improved, and the adhesive strength to the oil-adhered surface is maintained. The release imparting agent (D) can be used alone or in combination of two or more.

Various resins and additives can be added to the pressure-sensitive adhesive of the present invention, if desired, as long as the effects of the present invention are not impaired. Examples include silane coupling agents, heat or light stabilizers, ultraviolet absorbers, leveling agents, defoamers, antibacterial agents, humectants, vitamins, pigments, dyes, fragrances, and the like. These are compounded in an effective amount as required.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer, which is a cured product of the pressure-sensitive adhesive of the present invention, on a substrate. The pressure-sensitive adhesive sheet can be produced, for example, by applying a pressure-sensitive adhesive on a substrate and drying the pressure-sensitive adhesive. The adhesive layer may be provided on at least one surface of the substrate.

  In applying the adhesive, a suitable liquid medium, for example, a hydrocarbon solvent such as toluene, xylene, hexane, heptane; an ester solvent such as ethyl acetate and butyl acetate; a ketone solvent such as acetone and methyl ethyl ketone; dichloromethane And a halogenated hydrocarbon solvent such as chloroform, an ether solvent such as diethyl ether, methoxytoluene and dioxane, and an organic solvent such as another hydrocarbon solvent to adjust the viscosity. Can be heated to lower the viscosity.

  Examples of the base material include cellophane, plastic sheet, rubber, foam, cloth, rubber cloth, resin impregnated cloth, glass plate, wood, and the like, and may be plate-like or film-like. Further, the substrate can be used alone or in a multi-layer state in which a plurality of layers are laminated. Further, a substrate obtained by subjecting the surface of a substrate to a release treatment (hereinafter, referred to as a release sheet) can also be used.

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

  In the present invention, the method for applying the pressure-sensitive adhesive is not particularly limited, and may be a Meyer bar, an applicator, a brush, a spray, a roller, a gravure coater, a die coater, a lip coater, a comma coater, a knife coater, a reverse coater, a spin coater, and the like. No. The drying method is not particularly limited, and examples thereof include hot air drying, infrared rays, and a method using a reduced pressure method. The drying conditions depend on the curing form of the pressure-sensitive adhesive, the film thickness and the selected solvent, but usually hot air heating at about 60 to 130 ° C. is sufficient.

  The pressure-sensitive adhesive sheet of the present invention comprises (a) a pressure-sensitive adhesive applied to the release-treated surface of the release-treated film and dried, and a substrate is laminated on the surface of the pressure-sensitive adhesive layer; Can be obtained by directly coating and drying, and laminating a release-treated surface of a release-treated film on the surface of the pressure-sensitive adhesive layer.

  The thickness of the pressure-sensitive adhesive layer is preferably from 0.1 to 300 μm, more preferably from 1 to 200 μm, even more preferably from 3 to 150 μm.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Regarding the compounding ratio, values other than the solvent are shown in terms of solid content. The abbreviations of the materials used in the following examples are shown.

<(A1) Carboxyl group-containing monomer>
AA: acrylic acid MAA: methacrylic acid <(a2) alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms> 2EHA: 2-ethylhexyl acrylate NA: nonyl acrylate iDA: isodecyl acrylate <(a3) ) Alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms>
MA: methyl acrylate EA: ethyl acrylate PMA: propyl methacrylate <(a4) hydroxyl group-containing monomer>
HEA: 2-hydroxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate <Other monomers>
2MEA: 2-methoxyethyl acrylate BA: butyl acrylate

<Isocyanate curing agent (B)>
TDI-TMP: Trimethylolpropane adduct of tolylene diisocyanate <Curing agent other than isocyanate>
TGXA: N, N, N ', N'-tetraglycidyl-m-xylylenediamine HBAP: 2,2'-bishydroxymethylbutanoltris [3- (1-aziridinyl) propionate]
AlAA: Aluminum tris (acetylacetonate)

<Tackifier (C)>
P-135: Clearon P135 (hydrogenated terpene resin, softening point 135 ° C, manufactured by Yashara Chemical Co.)
M-100: Archon M-100 (hydrogenated petroleum resin, softening point 100 ° C, manufactured by Arakawa Industry Co., Ltd.)
P-85: Clearon P85 (hydrogenated terpene resin, softening point 85 ° C, manufactured by Yashara Chemical Co., Ltd.)
FTR-6110: FTR-6110 (non-hydrogenated petroleum resin, softening point 110 ° C, manufactured by Mitsui Chemicals, Inc.)
A-100: Superester A-100 (rosin ester resin, softening point 100 ° C, manufactured by Arakawa Chemical Industry Co., Ltd.)

<Release imparting agent (D)>
DOP: di-2-ethylhexyl phthalate (molecular weight: 390.56, solubility: less than 1 g / L) MAR: methyl O-acetyl ricinoleate (molecular weight: 354.52, solubility: less than 1 g / L) TBP: tributyl phosphate (molecular weight: 266.31) , Solubility 6g / L)

(Synthesis example 1)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction pipe (hereinafter, may be simply referred to as “reaction vessel”) was charged with 45.0 parts of 2-ethylhexyl acrylate and butyl acrylate. After charging 4.5 parts, 0.25 part of acrylic acid, 0.25 part of 2-hydroxyethyl acrylate, 20 parts of ethyl acetate, 20 parts of acetone, and 0.04 part of benzoyl peroxide (BPO), the reaction vessel is charged. Was replaced with nitrogen gas. Next, the mixture was heated to 80 ° C. while stirring under a nitrogen atmosphere to start the reaction. Further, in the dropping funnel, the same equimolar mixture (45.0 parts of 2-ethylhexyl acrylate, butyl acrylate 4.
5 parts, 0.25 part of acrylic acid, 0.25 part of 2-hydroxyethyl acrylate, 20 parts of ethyl acetate, 20 parts of acetone, and 0.04 part of BPO), and the mixture was added dropwise at a reflux temperature of 7 under a nitrogen atmosphere. The polymerization reaction was performed for an hour. After completion of the reaction, the mixture was cooled and diluted with toluene to obtain a copolymer solution having a nonvolatile content of 30% and a viscosity of 5000 mPa · s. When the weight average molecular weight (Mw) of the acrylic copolymer was measured using GPC, the weight average molecular weight was 910,000. Let the obtained copolymer be copolymer (A-1).

(Synthesis examples 2, 3, 6 to 8, 11, 12, 14, 17)
An acrylic copolymer was synthesized in the same manner as in Synthesis Example 1 except that the materials and the mixing ratios in Table 1 were changed.
(Synthesis examples 4, 5, 9, 10, 13, 15, 16)
Same as Synthesis Example 1 except that the materials and compounding ratios in Table 1 were changed, and that 0.04 part of BPO in Synthesis Example 1 was changed to 0.02 part of 2,2′-azobisisobutyronitrile (AIBN) Acrylic copolymers were synthesized by the methods described above.
Among the acrylic copolymers obtained in the above synthesis examples, the acrylic copolymers obtained in synthesis examples 1 to 15 correspond to the acrylic copolymer (A) and obtained in synthesis examples 16 and 17. The acrylic copolymer corresponds to an acrylic copolymer other than the acrylic copolymer (A).

<Weight average molecular weight (Mw)>
Mw was measured under the following conditions. Mw was determined by a calibration curve method using polystyrene having a known weight average molecular weight as a standard substance.
Apparatus name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: Four GMHXL manufactured by Tosoh Corporation and one HXL-H manufactured by Tosoh Corporation connected in series Mobile phase solvent: Tetrahydrofuran (THF)
Flow rate: 1.0 ml / min Column temperature: 40 ° C

(Example 1)
<Preparation of adhesive>
With respect to 100 parts of the nonvolatile content of the obtained acrylic copolymer (A), 2.0 parts of TDI-TMP was calculated as the isocyanate curing agent (B) in terms of the nonvolatile content, and P-135 was used as the tackifier (C). Was added, 10 parts of DOP was added as a release imparting agent (D), and ethyl acetate was added as a diluting solvent, followed by stirring to obtain an adhesive.

<Preparation of adhesive sheet>
38μm thick polyester separator [Product name "Super Stick" SP-PE
T38, manufactured by Lintec Co., Ltd., the same shall apply hereinafter) on the pressure-sensitive adhesive obtained above so that the thickness after drying is 50 μm, and dried in a hot-air oven at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer. Produced. After drying, it was laminated on a 25 μm-thick polyethylene naphthalate (PEN) film (Theonex, manufactured by Teijin Limited) and cured at 23 ° C. and 50% RH for 7 days to obtain an adhesive sheet.

<Oil surface adhesion>
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 100 mm in length. Then, in an environment of 23 ° C. and 50% RH, the adhesive layer exposed by peeling the separator from the adhesive sheet was uniformly coated with 2 g / m ² of engine oil (Apolloyl Promente SL / CF-4, manufactured by Idemitsu Kosan Co., Ltd.) on the surface. A stainless steel (SUS) plate and an uncoated SUS plate were adhered to each other, and reciprocated once with a 2 kg roll to prepare a measurement sample. After storing this measurement sample in an environment of 23 ° C. and 50% RH for 24 hours, a tensile tester (“Tensilon” manufactured by Orientec) was used at a peeling speed of 300 mm / min and a peeling angle of 180 °. The peel strength was measured. The ratio (A / B) between the peel strength A of the SUS plate coated with the oil on the surface and the peel strength B of the SUS plate not coated was determined and evaluated based on the following criteria.
：: A / B = 0.8 or more (excellent)
：: A / B = 0.6 or more and less than 0.8 (good)
Δ: A / B = 0.4 or more and less than 0.6 (usable)
×: A / B = less than 0.4 (cannot be used)

<Removability>
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 100 mm in length. Next, in a 23 ° C. and 50% RH environment, the pressure-sensitive adhesive layer exposed by peeling the separator from the sample was attached to a SUS plate, and reciprocated once with a 2 kg roll to prepare a measurement sample. After storing this measurement sample in an environment of 60 ° C. and 95% RH for 7 days, a tensile tester (“Tensilon” manufactured by Orientec) was used at a peeling speed of 300 mm / min and a peeling angle of 180 °. A peel test was performed. Next, the SUS plate surface after peeling was visually observed and evaluated based on the following criteria.
：: No fogging or adhesive residue was observed. (Excellent)
：: Fogging was observed in part, but no adhesive residue was left. (Good)
Δ: Fogging was observed as a whole, but no adhesive residue was left. (Available)
X: Clouding and adhesive residue are observed. (Usage prohibited)

<Tack>
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 200 mm in length. Then 23
In an environment of 50 ° C. and 50% RH, the pressure-sensitive adhesive layer exposed by peeling the separator from the sample was set on an inclined surface having an inclination angle of 30 °. Next, a steel ball (1/32 to 32/32 inch) was rolled on a sample having a running size of 100 mm and a glue surface of 100 mm, and the number of the diameter of the ball stopped near the center of the glue surface was recorded. The evaluation criteria are as follows.
：: The diameter number is 8 or more and 13 or less. (Good)
Δ: The diameter number is 4 or more and 7 or less, or 14 or more and 18 or less. (Available)
X: The diameter number is 3 or less, or 19 or more. (Usage prohibited)

<Water resistance>
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 100 mm in length. Then 23
In an environment of 50 ° C. and 50% RH, the pressure-sensitive adhesive layer exposed by peeling the separator from the sample was adhered to alkali glass, and reciprocated once with a 2 kg roll to prepare a measurement sample. After this measurement sample was immersed in ion-exchanged water for 24 hours in an environment of 40 ° C., the interface between the pressure-sensitive adhesive layer and the alkali glass was visually observed, and evaluated based on the following criteria.
：: No bubbles or floating are observed. (Good)
Δ: Fine bubbles and floating were slightly observed at the ends. (Available)
×: Bubbles and floating were observed over the entire surface. (Usage prohibited)

(Examples 2 to 31, Comparative Examples 1 to 9)
Except that the materials, compositions, and amounts shown in Tables 1 to 5 were changed, pressure-sensitive adhesives and pressure-sensitive adhesive sheets were produced, and measurement and evaluation were performed in the same manner as in Example 1. In addition, the numerical value in a table | surface represents a part unless there is particular notice, and the blank column represents not using.

Claims (10)

An adhesive containing an acrylic copolymer (A), an isocyanate curing agent (B), a tackifier (C) and a release agent (D),
The acrylic copolymer (A) contains a carboxyl group-containing monomer (a1) as a monomer unit constituting the copolymer,
The compounding amount of the isocyanate curing agent (B) is 0.3 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the acrylic copolymer (A),
The tackifier (C) contains a terpene resin and / or a petroleum resin,
The pressure-sensitive adhesive, wherein the release-imparting agent (D) includes one having a molecular weight of 250 or more and 1000 or less.   The acrylic copolymer (A) further comprises an alkyl (meth) acrylate (a2) having an alkyl group having 8 to 10 carbon atoms and an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms. The pressure-sensitive adhesive according to claim 1, comprising (a3).   The pressure-sensitive adhesive according to claim 1, wherein the acrylic copolymer (A) further includes a hydroxyl group-containing monomer (a4).   The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the isocyanate curing agent (B) has an aromatic ring.   The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the terpene resin includes a hydrogenated terpene resin, and the petroleum resin includes a hydrogenated petroleum resin.   The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the solubility of the release imparting agent (D) in water at 25 ° C is 10 g / L or less.   The pressure-sensitive adhesive according to any one of claims 1 to 6, which adheres to an adherend whose surface is partially covered with oil.   The alkyl (meth) acrylate (a3) having an alkyl group having 1 to 3 carbon atoms is contained in the monomer constituting the copolymer in an amount of 3% by mass or more and 20% by mass or less. The pressure-sensitive adhesive according to claim 1.   An adhesive sheet comprising a substrate and an adhesive layer which is a cured product of the adhesive according to any one of claims 1 to 8.   The pressure-sensitive adhesive sheet according to claim 9, which is attached to an adherend whose surface is partially covered with oil.