WO2020026935A1

WO2020026935A1 - Adhesive composition and surface protection film

Info

Publication number: WO2020026935A1
Application number: PCT/JP2019/029195
Authority: WO
Inventors: 佐藤　浩司; 朋和髭白; 優紀小松崎
Original assignee: Dic株式会社
Priority date: 2018-08-01
Filing date: 2019-07-25
Publication date: 2020-02-06
Also published as: CN112236494B; CN112236494A; JP6863524B2; JPWO2020026935A1

Abstract

The present invention addresses the problem of providing an adhesive composition which is capable of maintaining the transparency of a surface protection film even under high temperature, high humidity conditions. The present invention uses an adhesive composition which contains a urethane resin (A) and a curing agent (B), and which is configured such that: the urethane resin (A) is a reaction product of a polyol (a1) and a polyisocyanate (a2); the polyol (a1) contains a polymer polyol (a1-1) and a polyol (a1-2) having a carboxyl group; and the curing agent (B) contains a curing agent that has a functional group which is reactive with a carboxyl group.

Description

Adhesive composition and surface protective film

The present invention relates to a pressure-sensitive adhesive composition and a surface protective film.

表面 Surface protective films are used for the purpose of preventing dirt and scratches on the surface of various substrates. The surface protection film is attached to an optical member or the like, for example, in a manufacturing process of a display device, and is peeled off from the optical member or the like when the surface protection becomes unnecessary.

As a pressure-sensitive adhesive used for such a surface protection film, a pressure-sensitive adhesive containing a urethane polymer having an ester bond and a fatty acid ester and a curing agent is known (for example, see Patent Document 1). Further, an adhesive containing a urethane resin having a hydroxyl group, a curing agent, and a diester or triester of an organic acid is known (for example, see Patent Documents 2 and 3). Further, a pressure-sensitive adhesive containing a polyurethane having two or more hydroxyl groups, a crosslinking agent, a carbodiimide compound, and an organic solvent is known (for example, see Patent Document 4). Further, an adhesive containing a polyurethane obtained by reacting a polyisocyanate, a polyol, a dioxycarboxylic acid, and the like, and a polyisocyanate curing agent is known (for example, see Patent Document 5).

Japanese Patent No. 5861794 Japanese Patent No. 5974311 Japanese Patent No. 5974313 Japanese Patent No. 6032388 JP 2010-180290 A

However, when the pressure-sensitive adhesives described in Patent Documents 1 to 5 are used for the surface protective film, the surface protective film may become white and cloudy (white fog) when left under high temperature and high humidity. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive composition capable of maintaining the transparency of a surface protective film even under high temperature and high humidity.

The pressure-sensitive adhesive composition of the present invention comprises a urethane resin (A) and a curing agent (B), wherein the urethane resin (A) is a reaction product of a polyol (a1) and a polyisocyanate (a2), (A1) contains a polymer polyol (a1-1) and a polyol having a carboxyl group (a1-2), and the curing agent (B) contains a curing agent having a functional group capable of reacting with a carboxyl group. It is a thing.

粘着 The pressure-sensitive adhesive composition of the present invention can maintain transparency of the obtained surface protective film even after being placed under high temperature and high humidity.

粘着 The pressure-sensitive adhesive composition of the present invention contains a urethane resin (A) and a curing agent (B).

The urethane resin (A) is a reaction product of the polyol (a1) and the polyisocyanate (a2).

The polyol (a1) is a compound having two or more hydroxyl groups in one molecule, and includes a polymer polyol (a1-1) and a polyol (a1-2) having a carboxyl group.

The number average molecular weight of the polymer polyol (a1-1) is preferably at least 500, more preferably at least 700, even more preferably at least 900, preferably at most 10,000, more preferably at most 5,000, even more preferably. Is 3,000 or less, particularly preferably 1,200 or less.
In the present invention, the number average molecular weight and the weight average molecular weight represent values measured by gel permeation chromatography in terms of polystyrene.

ポリマー As the polymer polyol (a1-1), one or more kinds can be used, and examples thereof include a polyether polyol, a polyester polyol, and a polycarbonate polyol.

The polyether polyol is obtained by subjecting one or more compounds having two or more active hydrogen atoms (for example, a molecular weight of 50 to less than 500) to an addition polymerization of an alkylene oxide as an initiator, or the active hydrogen A compound obtained by subjecting a cyclic ether to ring-opening polymerization using one or more compounds having two or more atoms (for example, a molecular weight of 50 or more and less than 500) as an initiator as required.

As the compound having two or more active hydrogen atoms, one or more compounds can be used. For example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, Examples include 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, bisphenol A, glycerin, trimethylolethane, and trimethylolpropane.

As the alkylene oxide, one or more kinds can be used, and examples thereof include ethylene oxide, propylene oxide, butylene oxide, and epichlorohydrin. Examples of the cyclic ether include tetrahydrofuran and alkyl-substituted tetrahydrofuran.

Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, a polytetramethylene glycol derivative obtained by reacting tetrahydrofuran with an alkyl-substituted tetrahydrofuran, and a poly (ethylene copolymer) obtained by copolymerizing neopentyl glycol and tetrahydrofuran. A tetramethylene glycol derivative or the like can be used. Of these, polypropylene glycol, polytetramethylene glycol (PTMG), and polytetramethylene glycol derivative (PTXG) are preferable as the polyether polyol.

The polyether polyol includes at least a polyether polyol having at least 10% by mass of oxyalkylene units having 4 or more carbon atoms. By including an oxyalkylene unit having 4 or more carbon atoms, a change in surface characteristics can be easily suppressed.

In the polymer polyol (a1-1), the content of the polyether polyol is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and preferably 100% by mass or less. is there.

Examples of the polyester polyol include an esterification product of a low-molecular polyol and a polycarboxylic acid; a ring-opening polymer of a cyclic ester compound such as ε-caprolactone; a copolyester of the esterification product or a ring-opening polymer. Can be used.

As the polycarboxylic acid, for example, succinic acid, adipic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, and the like. An anhydride or an esterified product may be used.

As the polycarbonate polyol, for example, a reaction between a carbonate ester and / or phosgene and a low molecular weight polyol can be mentioned. As the carbonic acid ester, one or more kinds can be used. For example, aliphatic carbonates such as alkyl carbonate (eg, methyl carbonate, ethyl carbonate, etc.) and dialkyl carbonate (eg, dimethyl carbonate, diethyl carbonate, etc.) Carbonates containing an alicyclic structure such as cyclocarbonate (hereinafter, “containing an alicyclic structure” may be simply referred to as “alicyclic”); and aromatic carbonates such as diphenyl carbonate. Among them, aliphatic carbonates and alicyclic carbonates are preferable, aliphatic carbonates are more preferable, and dialkyl carbonates are more preferable.

Examples of the low-molecular polyol capable of reacting with the carbonate or phosgene include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, and tripropylene glycol. 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, -Methyl-1,3-propanediol, Pentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol Alicyclic polyols such as 1,4-cyclohexanedimethanol; hydroquinone, resorcin; aromatic polyols such as bisphenol A, bisphenol F, and 4,4′-biphenol.

As the low molecular polyol, aliphatic polyols and alicyclic polyols are preferable, and aliphatic polyols are more preferable. 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl- 1,5-pentanediol and 1,6-hexanediol are more preferred.

Examples of the polycarbonate polyol include an aliphatic polycarbonate polyol which is a reaction product of an aliphatic carbonate and an aliphatic polyol; a reaction product of an aliphatic carbonate and / or an alicyclic carbonate and an aliphatic polyol and / or an alicyclic polyol. Certain alicyclic polycarbonate polyols are preferred.

In the polyol (a1), the content of the polymer polyol (a1-1) is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and preferably 100% by mass or less. is there.

As the polyol having a carboxyl group (a1-2), one or more kinds can be used. For example, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2- Hydroxy acids such as dimethylol butyric acid and 2,2-dimethylol valeric acid; and reaction products of the polyol having a carboxy group with the polycarboxylic acid. The polyol (a1-2) having a carboxyl group is preferably a hydroxy acid, and more preferably 2,2-dimethylolpropionic acid.

The content of the polyol (a1-2) having a carboxyl group is preferably at least 1 part by mass, more preferably at least 2 parts by mass, and still more preferably 3 parts by mass, per 100 parts by mass of the polymer polyol (a1-1). It is at least 50 parts by mass, more preferably at most 30 parts by mass, even more preferably at most 20 parts by mass.

In the polyol (a1), the total content of the polymer polyol (a1-1) and the polyol (a1-2) having a carboxyl group is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably. Is 90% by mass or more, preferably 100% by mass or less.

The polyol (a1) may contain another polyol (a1-3) other than the polymer polyol (a1-1) and the polyol having a carboxyl group (a1-2).

One or more polyisocyanates (a2) can be used, and examples thereof include diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, triene diisocyanate, and naphthalene. Aromatic polyisocyanates such as diisocyanate, xylylene diisocyanate and tetramethyl xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 4,4 ′ Dicyclohexylmethane diisocyanate, 2,4- and / or 2,6-methylcyclohexane diisocyanate, cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1,2-dicarboxylate and 2,5- and / or 2,6- Examples include alicyclic polyisocyanates such as norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, and hydrogenated xylylene diisocyanate. Of these, aliphatic polyisocyanates and alicyclic polyisocyanates are preferred.

The molar ratio (isocyanate group / hydroxyl group) of the isocyanate group contained in the polyisocyanate (a2) to the hydroxyl group contained in the polyol (a1) is 0.5 or more, preferably 0.7 or more, It is more preferably 0.8 or more, further preferably 0.85 or more, less than 1, preferably 1 or less, and more preferably 0.95 or less.

The urethane resin may be one obtained by further reacting a chain extender with the polyol (a1) and the polyisocyanate (a2). Further, the molar ratio (isocyanate group / hydroxyl group) of the isocyanate group contained in the polyisocyanate (a2) and the hydroxyl group contained in the polyol (a1) is caused to react in a ratio of an isocyanate group excess of 1.0 or more. After the isocyanate-terminated prepolymer is obtained, it may be reacted with a chain extender. When preparing an isocyanate-terminated prepolymer, the molar ratio (isocyanate group / hydroxyl group) of the isocyanate group contained in the polyisocyanate (a2) to the hydroxyl group contained in the polyol (a1) is 1.0 or more. , Preferably 1.05 or more, more preferably 1.1 or more, preferably less than 3.0, more preferably 2.5 or less, and still more preferably 2.0 or less.

As the chain extender, one or more kinds can be used, and examples thereof include a compound having two or more active hydrogen atoms and a polyamine. Examples of the compound having two or more active hydrogen atoms include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and 3-methyl- 1,5-pentanediol, 1,6-hexanediol, 3,3′-dimethylolheptane, neopentyl glycol, 3,3-bis (hydroxymethyl) heptane, diethylene glycol, dipropylene glycol, polyoxypropylene glycol, Aliphatic chain extenders such as polyoxybutylene glycol, glycerin and trimethylolpropane; 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 4-cyclohexanedimeta , Hydroxypropylcyclohexanol, tricyclo [5.2.1.0 ^2,6 ] decane-dimethanol, bicyclo [4.3.0] -nonanediol, dicyclohexanediol, bicyclo [4.3.0] Alicyclic chain elongation such as nadimethanol, spiro [3.4] octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, 1,3-adamantanediol Aliphatic alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,3-butanediol; cyclohexanedimethanol and the like. Alicyclic glycol, etc. Preferred. Examples of the polyamine include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, and 3,3′-diamine. Dimethyl-4,4'-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, N-hydroxymethylaminoethylamine, N-ethylaminoethylamine, N-methylaminopropylamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, hydrazine, N, N'-dimethylhydrazine, 1,6-hexamethylenebishydrazine, succinic dihydrazide, adipic dihydrazide, glutaric dihydrazide, sebacic dihydrazide, isophthalic dihydrazide And polyamine extenders such as β-semicarbazidepropionic hydrazide, 3-semicarbazide-propyl-carbazate, and semicarbazide-3-semicarbazidemethyl-3,5,5-trimethylcyclohexane.

When the chain extender is contained, its content is preferably at least 0.01% by mass, more preferably at least 0.05% by mass, further preferably at least 0.1% by mass, based on the polyol (a1). , Preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less.

The urethane resin (A) may be a product obtained by further reacting a reaction product of the polyol (a1), the polyisocyanate (a2), and a chain extender used as required with a terminal terminator. By using the terminal stopper, the isocyanate group can be deactivated.

The terminal terminator is preferably an alcohol, for example, a monofunctional alcohol such as methanol, ethanol, propanol, or butanol; a bifunctional alcohol such as 1,2-propylene glycol or 1,3-butylene glycol; a polyfunctional polyol; Examples thereof include alkanolamine compounds such as amines (eg, ethanolamine) and alkanoldiamines (eg, diethanolamine).

When the terminal stopper is used, the molar ratio of the group having an active hydrogen atom contained in the terminal stopper to the isocyanate group contained in the polyisocyanate (a2) is preferably 1.0 or more, more preferably 1 or more. 0.2 or more, more preferably 1.5 or more, preferably 10.0 or less, more preferably 5.0 or less, and even more preferably 3.0 or less.

The acid value of the urethane resin (A) is preferably 5 mgKOH / g or more, more preferably 7 mgKOH / g or more, preferably 50 mgKOH / g or less, more preferably 45 mgKOH / g or less, and further preferably 35 mgKOH / g or less. .

The number average molecular weight of the urethane resin (A) is preferably 7,000 or more, more preferably 9,000 or more, further preferably 10,000 or more, preferably 80,000 or less, more preferably 60,000 or less. 000 or less, more preferably 40,000 or less.

The weight average molecular weight of the urethane resin (A) is preferably 10,000 or more, more preferably 20,000 or more, still more preferably 30,000 or more, preferably 100,000 or less, more preferably 70,000. Or less, more preferably 50,000 or less.

分子 The molecular weight dispersity of the urethane resin (A) is preferably 1.8 or more, more preferably 2 or more, still more preferably 2.3 or more, preferably 7 or less, more preferably 5 or less.

において In the present specification, the number average molecular weight and the weight average molecular weight can be measured as conversion values using polystyrene as a standard sample by gel permeation chromatography.

The urethane resin (A) can be produced by reacting the polyol (a1) with the polyisocyanate (a2) and, if necessary, further reacting a chain extender and / or a terminal stopper. The reaction may be performed in the presence of an organic solvent, and in the case of the reaction, a urethanation catalyst may be allowed to coexist.

As the organic solvent, one or more kinds can be used. For example, aromatic hydrocarbon solvents such as toluene; ester solvents such as ethyl acetate and butyl acetate; acetone, methyl ethyl ketone, cyclohexanone, 3-pentanone and the like. Ketone solvents; ether solvents such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, ethyl carbitol; nitrile solvents such as acetonitrile, propionitrile, isobutyronitrile, valeronitrile; dimethyl Sulfoxide solvents such as sulfoxide; amide solvents such as methylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone;

Examples of the urethanization catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine, metal salts such as potassium acetate, zinc stearate, and tin octylate; dibutyltin laurate; dioctyltin dineodecanate; and zirconium tetraacetyl. An organometallic compound such as acetonate can be used.

The curing agent (B) includes a curing agent (b1) having a functional group capable of reacting with a carboxyl group. Examples of the functional group capable of reacting with the carboxyl group include an epoxy group, a carbodiimide bonding group (—N ＝ C ＝ N—), an aziridinyl group, and an oxazolyl group. Examples of the curing agent (b1) having a functional group capable of reacting with a carboxyl group include a compound having two or more functional groups capable of reacting with a carboxyl group. Examples of the curing agent (b1) having a functional group capable of reacting with the carboxyl group include an epoxy curing agent, a carbodiimide curing agent, an aziridine curing agent, and an oxazoline curing agent, and these may be used in combination. Especially, it is preferable to contain at least one of an epoxy curing agent and a carbodiimide curing agent.

As the epoxy curing agent, one or more kinds can be used. For example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol Diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, cyclohexane dimethanol diglycidyl ether, resorcinol diglycidyl ether, phenol (EO) 5 glycidyl ether, bis- (p-hydroxyphenyl) methane Diglycidyl ether, 2,2-bis- (p-hydroxyphenyl) propane diglycidyl ether, tri Aliphatic, alicyclic or aromatic such as-(p-hydroxyphenyl) methane polyglycidyl ether, 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane polyglycidyl ether, lauryl alcohol (EO) 15 glycidyl ether Diglycidyl ether of an aromatic polyol compound; glycerin triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycidyl ether Polyglycidyl ethers of aliphatic, cycloaliphatic or aromatic polyol compounds such as glycerol polyglycidyl ether; N, N-diglycidyl Aniline, N, N-diglycidyl toluidine 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, N, N, N ′ Polyglycidyl ethers of amine compounds such as N, N'-tetraglycidyl-bis- (p-aminophenyl) methane; diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl naphthalenedicarboxylate, polyglycidyl trimellitate Diglycidyl esters or polyglycidyl esters of fatty acids or aromatic acids such as diglycidyl adipic acid ester and diglycidyl sebacate; triglycidyl aminophenol; triglycidyl tris (2-hydroxyethyl) isocyanurate, trig Triglycidyl isocyanurate; ortho-cresol type epoxy, and the like phenol novolac type epoxy.

場合 When the epoxy curing agent is used, an epoxy curing catalyst may coexist. Examples of the epoxy curing catalyst include tertiary amine compounds such as imidazole and dimethylaminopyridine; phosphorus compounds such as triphenylphosphine; boron trifluoride amine complexes such as boron trifluoride and boron trifluoride monoethylamine complex; Organic acid compounds such as thiodipropionic acid; benzoxazine compounds such as thiodiphenol benzoxazine and sulfonyl benzoxazine; and sulfonyl compounds.

As the carbodiimide curing agent, one or more kinds can be used. For example, N, N′-di-o-toluylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-di-2, 6-dimethylphenylcarbodiimide, N, N'-bis (2,6-diisopropylphenyl) carbodiimide, N, N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N, N'-di-2, 2-di-tert. -Butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p- Examples include hydroxyphenylcarbodiimide, N, N'-di-cyclohexylcarbodiimide, N, N'-di-p-toluylcarbodiimide and the like.

As the aziridine curing agent, one or more kinds can be used. For example, 2,2′-bishydroxymethylbutanol tris [3- (1-aziridinyl) propionate], 4,4′-bis (ethylene Iminocarbonylamino) diphenylmethane and the like.

As the oxazoline curing agent, one or more kinds can be used. For example, 2′-methylenebis (2-oxazoline), 2,2′-ethylenebis (2-oxazoline), 2,2′-ethylene Bis (4-methyl-2-oxazoline), 2,2'-propylenebis (2-oxazoline), 2,2'-tetramethylenebis (2-oxazoline), 2,2'-hexamethylenebis (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-2-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), Oxazoline compounds such as 2,2'-bis (4-phenyl-2-oxazoline); vinyls such as 2-isopropenyl-2-oxazoline and 2-isopropenyl-4,4-dimethyl-2-oxazoline Copolymers thereof having a dimer copolymerized oxa z Ron groups.

The molar ratio of the carboxyl group in the urethane resin (A) to the group capable of reacting with the carboxyl group contained in the curing agent (B) (carboxyl group / functional group capable of reacting with the carboxyl group) is preferably 1 or more. , More preferably 1.2 or more, further preferably 1.5 or more, preferably 5 or less, more preferably 4 or less, and still more preferably 3 or less.

In the curing agent (B), the content of the curing agent (b1) having a functional group capable of reacting with the carboxyl group is preferably 10% by mass or more, more preferably 30% by mass or more, and still more preferably 40% by mass. Or less, and preferably 100% by mass or less.

The curing agent (B) may further include another curing agent (b2) in addition to the curing agent (b1) having a functional group capable of reacting with the carboxyl group. Examples of the other curing agent (b2) include an isocyanate curing agent.

As the isocyanate curing agent, one or more kinds can be used. For example, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate Polyisocyanates; trimethylolpropane adducts thereof; isocyanurates thereof; and burettes thereof. Among these, it is preferable to use trimethylolpropane adduct of polyisocyanate and isocyanurate of polyisocyanate.

When the other curing agent (b2) is contained, the content of the other curing agent (b2) is preferably based on 100 parts by mass of the curing agent (b1) having a functional group capable of reacting with the carboxyl group. It is at least 5 parts by mass, more preferably at least 20 parts by mass, even more preferably at least 30 parts by mass, preferably at most 200 parts by mass, more preferably at most 150 parts by mass, even more preferably at most 130 parts by mass.

The content of the curing agent (B) is preferably at least 0.1 part by mass, more preferably at least 0.5 part by mass, and preferably at least 10 parts by mass, based on 100 parts by mass of the urethane resin (A). Or less, more preferably 7 parts by mass or less.

The total content of the urethane resin (A) and the curing agent (B) in the solid content of the pressure-sensitive adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass. %, Preferably 100% by mass or less.
In the present specification, the solid content of the pressure-sensitive adhesive composition refers to a portion excluding a solvent contained in the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition may further include a curing catalyst. Examples of the curing catalyst include the same compounds as the compounds exemplified as the urethanization catalyst and the epoxy curing catalyst. When the curing catalyst is contained, its content is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, and still more preferably 0.01 part by mass, based on 100 parts by mass of the urethane resin (A). It is at least 1 part by mass, preferably at most 1 part by mass, more preferably at most 0.1 part by mass, further preferably at most 0.05 part by mass.

The pressure-sensitive adhesive composition may further contain a plasticizer. Examples of the plasticizer include aliphatic polycarboxylic acid esters such as adipic acid ester, citrate ester, sebacate ester, azelate ester, and maleate ester; terephthalate ester, isophthalate ester, phthalate ester and trimellitate ester. And aromatic polycarboxylic acid esters such as benzoic acid esters; ether-modified polyesters; epoxy-modified polyesters; polyesters formed from polycarboxylic acids and polyols.

When the composition contains the plasticizer, the content of the plasticizer is preferably at least 0.1 part by mass, more preferably at least 1 part by mass, and preferably at least 50 parts by mass, based on 100 parts by mass of the urethane resin (A). It is at most 40 parts by mass, more preferably at most 30 parts by mass, even more preferably at most 30 parts by mass.

The pressure-sensitive adhesive composition may further contain a solvent. Examples of the solvent include the same compounds as the compounds exemplified as the organic solvent. When the organic solvent is contained, the content is preferably 20% by mass or more, more preferably 30% by mass or more, preferably 80% by mass or less, more preferably 70% by mass or less in the pressure-sensitive adhesive composition. It is. In the pressure-sensitive adhesive composition of the present invention, the content of water in the solvent is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 1% by mass or less, and the lower limit is 0% by mass. .

The pressure-sensitive adhesive composition further includes, as other additives, a silane coupling agent, an antioxidant, a light stabilizer, a rust inhibitor, a thixotropy-imparting agent, a sensitizer, a polymerization inhibitor, a leveling agent, and a tackifier. Agents, antistatic agents, flame retardants and the like. The content of the other additive in the pressure-sensitive adhesive composition is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 1% by mass or less, and the lower limit is 0% by mass.

By applying the pressure-sensitive adhesive composition to a substrate, removing the solvent as necessary, and aging as necessary, it is possible to form a pressure-sensitive adhesive layer that is a cured product of the pressure-sensitive adhesive composition. . The thickness of the adhesive layer is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, preferably 200 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less.

方法 As a method of forming a sheet with the pressure-sensitive adhesive composition, for example, a method of applying the pressure-sensitive adhesive composition on a plastic substrate, and drying and curing the same is exemplified.

Examples of the plastic substrate include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polyolefin resins such as polyethylene and polypropylene; polyacrylic resins; polyvinyl chloride resins; polypropylene ethylene vinyl alcohol; A sheet or a film obtained using a polyurethane resin; a polyamide resin; a polyimide resin or the like. The surface of these plastic substrates may be subjected to a release treatment, an antistatic treatment, a corona treatment, or the like. The thickness of the plastic substrate is, for example, in the range of 10 to 200 μm.

方法 Examples of a method for applying the pressure-sensitive adhesive composition to the plastic substrate include a coating method using a roll coater, a gravure coater, a reverse coater, a spray coater, an air knife coater, a die coater, or the like.

The pressure-sensitive adhesive layer, which is a cured product of the pressure-sensitive adhesive composition, can suppress changes in the surface characteristics of the base material before and after peeling, and can be used as a surface protection film, particularly, a display device and the like. It is useful as a surface protective film for protecting the information display section of the electronic device.

Hereinafter, the present invention will be described more specifically with reference to examples.

(Production Example 1: Production of urethane resin (I))
477 polytetramethylene ether glycol (number average molecular weight: 1,010.9, hydroxyl value: 111.0) was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube under a nitrogen stream. 0.62 parts by mass of neopentyl glycol and 0.28 parts by mass of neopentyl glycol were added and mixed uniformly. Then, 133.04 parts by mass of isophorone diisocyanate was added, and then 0.1 part by mass of tin octoate was added. By the reaction, a urethane prepolymer (a) having an isocyanate group at a molecular terminal was obtained.

Next, the urethane prepolymer (a) obtained by the above method is cooled to 60 ° C., and 14.96 parts by mass of 2,2-bis (hydroxymethyl) propionic acid and 268.24 parts by mass of methyl ethyl ketone are added. After adding 0.3 parts by mass of tin and reacting at 75 ° C. for about 5 hours, a solution of urethane prepolymer (b) having an isocyanate group at a molecular end in methyl ethyl ketone (solid content: 70% by mass) was obtained.

Next, the methyl ethyl ketone solution of the urethane prepolymer (b) obtained by the above method was cooled to 50 ° C., and 2.39 parts by weight of diethanolamine as a terminal terminator was added to confirm that the isocyanate had disappeared. Then, the mixture was cooled to room temperature to obtain a methyl ethyl ketone solution of the urethane resin (I) (solid content: 50% by mass). The acid value of this urethane resin (I) is 10 mgKOH / g, the molecular weight distribution by GPC is as follows: number average molecular weight (Mn) is 10,389, weight average molecular weight (Mw) is 56,341, and molecular weight dispersity (Mw / Mn). Was 5.43.

(Production Example 2: Production of urethane resin (II))
405. Polytetramethylene ether glycol (number-average molecular weight: 1,010.9, hydroxyl value: 111.0) in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube under a nitrogen stream. After adding 26 parts by mass and 2.02 parts by mass of neopentyl glycol and uniformly mixing, 170.79 parts by mass of isophorone diisocyanate was added, and then 0.2 parts by mass of tin octoate was added, followed by reaction at 90 ° C. for about 3 hours. As a result, a urethane prepolymer (c) having an isocyanate group at a molecular terminal was obtained.
Next, the urethane prepolymer (c) obtained by the above method is cooled to 60 ° C., and 44.65 parts by mass of 2,2-bis (hydroxymethyl) propionic acid and 266.88 parts by mass of methyl ethyl ketone are added. After adding 0.3 parts by mass of tin and reacting at 75 ° C. for about 5 hours, a solution of a urethane prepolymer (d) having an isocyanate group at a molecular end in methyl ethyl ketone (solid content: 70% by mass) was obtained.

Subsequently, the methyl ethyl ketone solution of the urethane prepolymer (d) obtained by the above method was cooled to 50 ° C., and 3.07 parts by mass of diethanolamine as a terminal terminator was added to confirm that the isocyanate had disappeared. Then, the mixture was cooled to room temperature to obtain a urethane resin (II) solution in methyl ethyl ketone (solid content: 50% by mass). The acid value of this urethane resin (I) is 30 mgKOH / g, the molecular weight distribution by GPC is as follows: number average molecular weight (Mn) is 10,063, weight average molecular weight (Mw) is 56,728, and molecular weight dispersity (Mw / Mn). Was 5.64.

(Production Example 3: Production of urethane resin (III))
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, a polyester diol comprising 3-methyl-1,5-pentanediol and adipic acid (number-average molecular weight 977.44) was placed under a nitrogen stream. , Hydroxyl value: 114.8) 322.83 parts by mass and ethyl acetate 422.76 parts by mass were added and uniformly mixed, and then 100.00 parts by mass of hexamethylene diisocyanate was added, and then 0.01 part by mass of dioctyltin dineodecanate. Was added thereto, and the mixture was reacted at 75 ° C. for about 3 hours to obtain an ethyl acetate solution of a urethane prepolymer (e) having an isocyanate group at a molecular terminal (solid content: 50% by mass).

Next, the ethyl acetate solution of the urethane prepolymer (e) obtained by the above method was cooled to 40 ° C., and polyoxyethylene polyoxypropylene triol (“Sannicks GL-3000” manufactured by Sanyo Chemical Co., Ltd., molar ratio [EO] / PO] = 25/75, number average molecular weight; 3,077.1, hydroxyl value: 54.7) 948.55 parts by mass, ethyl acetate 315.25 parts by mass, and after uniform mixing, at 65 ° C. The reaction was allowed to proceed for about 6 hours. When the NCO% became 0.01% or less, the mixture was cooled to 60 ° C., and 3.43 parts by mass of methanol as a terminal terminator was added. 231.66 parts by mass of ethyl was added, and the mixture was cooled to room temperature to obtain a solution of urethane resin (III) in ethyl acetate (solid content: 50% by mass). This urethane resin (III) has an acid value of 0 mgKOH / g, a molecular weight distribution by GPC, a number average molecular weight (Mn) of 23,434, a weight average molecular weight (Mw) of 129,370, and a molecular weight dispersity (Mw / Mn). Was 5.52.

(Example 1)
Immediately before producing a sheet, a neurate of hexamethylene diisocyanate ("Asahi Kasei Corporation") as an isocyanate curing agent was added to 100 parts by mass of a methyl ethyl ketone solution (solid content: 50% by mass) of the urethane resin (I) obtained in Production Example 1. 1.72 parts by mass of Duranate TKA-100, hereinafter abbreviated as "TKA-100"), 2.00 parts by mass of a 1% by mass solution of dioctyltin dineodecanate in methyl ethyl ketone as an isocyanate curing catalyst, and 0.50 parts by mass of acetylacetone 1.52 parts by mass of an aliphatic polyglycidyl ether ("CR-5L" manufactured by DIC Corporation, hereinafter abbreviated as "CR-5L") as an epoxy curing agent, and 0.05% of triphenylphosphine as an epoxy curing catalyst. Parts by mass, 29.82 parts by mass of methyl ethyl ketone To obtain a pressure-sensitive adhesive composition (1) (solid content: 40 wt%).

(Example 2)
Immediately before producing a sheet, 1.72 parts by mass of “Duranate TKA-100” was added to 100 parts by mass of a solution of the urethane resin (II) in methyl ethyl ketone (solid content: 50% by mass) obtained in Production Example 2. 2.00 parts by mass of a 1% by mass solution of dioctyltin dineodecanate in methyl ethyl ketone as an isocyanate curing catalyst, 0.50 parts by mass of acetylacetone, 4.57 parts by mass of "CR-5L" as an epoxy curing agent, and triphenyl as an epoxy curing catalyst 0.14 parts by mass of phosphine, 2.87 parts by mass of N-methyldiethanolamine, and 34.51 parts by mass of methyl ethyl ketone were mixed to obtain a pressure-sensitive adhesive composition (2) (solid content: 40% by mass).

(Example 3)
In 100 parts by mass of the urethane resin (II) obtained in Production Example 2 in methyl ethyl ketone solution (solid content: 50% by mass), immediately before producing a sheet, a carbodiimide curing agent in a methyl ethyl ketone solution (carbodilite manufactured by Nisshinbo Chemical Inc.) was used as a carbodiimide curing agent. V-09B ", a solid content of 70.26% by mass, hereinafter abbreviated as" V-09B "), 15.91 parts by mass, and 37.03 parts by mass of methyl ethyl ketone, and the pressure-sensitive adhesive composition (3) (solid 40% by mass).

(Comparative Example 1)
In 100 parts by mass of the urethane resin (III) obtained in Production Example 3 in ethyl acetate (solid content: 50% by mass), immediately before producing a sheet, 5.00 parts by mass of "Duranate TKA-100" as an isocyanate curing agent was used. Parts, 2.00 parts by mass of a 1% by mass solution of dioctyltin dineodecanate in ethyl acetate as an isocyanate curing catalyst, 0.50 parts by mass of acetylacetone, and 32.50 parts by mass of ethyl acetate were mixed, and the pressure-sensitive adhesive composition (X1) (solid 40% by mass).

[Processing method of adhesive sheet]
The obtained pressure-sensitive adhesive composition was applied on the surface of a polyethylene terephthalate film having a thickness of 50 μm so that the film thickness after drying was 65 μm, and dried at 60 ° C. for 3 minutes and further at 120 ° C. for 3 minutes. . A 38 μm-thick polyethylene terephthalate film whose surface was subjected to a mold release treatment was bonded thereto and cured at 40 ° C. for 3 days to obtain an adhesive sheet.

[Evaluation method for white fog]
What cut | disconnected the surface protective film obtained by the Example and the comparative example into 50 mm x 70 mm was used as the test piece. A single-sided tape having a thickness of 150 μm was cut into 40 mm × 60 mm, and the inner side was cut out to obtain a frame having a thickness of 150 μm and a width of 10 mm. The prepared frame was attached to a glass plate, and a test piece was attached thereon. At this time, since the thickness of the frame is thicker than the thickness of the adhesive, air bubbles are contained on both sides of the frame. After pasting, it was allowed to stand still for 3 days in an environment of a temperature of 85 ° C and a humidity of 85%, and then taken out in an environment of 23 ° C and left for 1 hour. The surface protection film was peeled off from the glass plate, and white fog where bubbles were present was evaluated.

White fog was evaluated as follows.
○: No white fog △: Thin but white fog ×: White fog

Examples 1 to 3 are examples of the present invention, and were able to maintain transparency even after being placed under high temperature and high humidity. Comparative Example 1 did not contain a curing agent having a functional group capable of reacting with a carboxyl group, and after being placed under high temperature and high humidity, the transparency was reduced (white fog was generated).

Claims

Including a urethane resin (A) and a curing agent (B),
The urethane resin (A) is a reaction product of a polyol (a1) and a polyisocyanate (a2),
The polyol (a1) includes a polymer polyol (a1-1) and a polyol having a carboxyl group (a1-2);
An adhesive composition wherein the curing agent (B) contains a curing agent having a functional group capable of reacting with a carboxyl group.
The pressure-sensitive adhesive composition according to claim 1, wherein the urethane resin (A) has an acid value of 5 mgKOH / g or more and 50 mgKOH / g or less.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the curing agent (B) further contains an isocyanate curing agent.
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the content of the curing agent (B) is 1 part by mass or more and 50 parts by mass or less based on 100 parts by mass of the urethane resin (A). .
粘着 A pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 4.
A surface protective film comprising the pressure-sensitive adhesive sheet according to claim 5.