JP7146745B2 - Adhesive, adhesive sheet, method for producing adhesive sheet, and image display device - Google Patents

Description

The present invention relates to an adhesive, an adhesive sheet, a method for producing an adhesive sheet, and an image display device.

Adhesives and adhesive sheets using them are widely used in various industrial fields. Specific uses include, for example, a protective film that is used by being attached to the surface of glass or the like. Examples of the glass include window glass of mobile phones, smart phones, automobiles, buildings, and the like.

The adhesive includes, for example, an acrylic resin-based adhesive, a rubber-based adhesive, a urethane adhesive, and the like. Among these, urethane adhesives have properties such as the ability to be peeled off after being applied (hereinafter referred to as re-peelability) and the ability to prevent air bubbles from being caught in the interface between the adhesive layer and the adherend (hereinafter referred to as wettability). It is widely used because of its excellent properties (Patent Document 1, etc.).

JP 2016-186064 A

In recent years, pressure-sensitive adhesives used in surface-protecting pressure-sensitive adhesive sheets and the like are required to have removability, wettability, and resistance to contamination of adherends. This is because products such as plastics, glass, etc., which have adhesives attached to their surfaces, may be transported or stored for a long period of time. Here, the adherend contamination resistance means that even if the product to which the adhesive sheet is attached is placed under high temperature and high humidity conditions for a long time, the adherend will not be contaminated by the adhesive when the adhesive sheet is removed. Say something that won't happen. Since the degree of contamination differs depending on the type of material (adherend) to which the pressure-sensitive adhesive is applied and the environment in which the product is left for a long time, the required resistance to contamination of the adherend also differs. Conceivable causes of contamination include denaturation and contamination derived from the material of the adherend, in addition to adhesive residue derived from the adhesive.

Therefore, the present invention provides a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a method for producing the pressure-sensitive adhesive sheet, and an image display device that can satisfy removability, wettability, and resistance to contamination of adherends under high temperature and high humidity conditions. intended to

前記化学式（I）中、
Ｒ^１およびＲ^２は、それぞれ、水素原子、炭化水素基またはアリール基であり、
Ｒ^１およびＲ^２は同一であっても異なっていてもよく、
Ｒ^１およびＲ^２の少なくとも一方は、炭化水素基またはアリール基である。

前記化学式（II）および（III）中、
Ｒ^３およびＲ^４は、それぞれ、水素原子、炭化水素基またはアリール基であり、
Ｒ^３およびＲ^４は同一であっても異なっていてもよく、
Ｒ^３およびＲ^４の少なくとも一方は、炭化水素基またはアリール基であり、
ＡＯはアルキレンオキシド基であり、各ＡＯは同一でも異なっていてもよく、
ｎは１以上の整数を表し、各ｎは同一でも異なっていてもよい。In order to achieve the above object, the pressure-sensitive adhesive of the present invention is
a polyurethane prepolymer (A);
including at least one selected from the group consisting of an organic acid (B-1), an acidic phosphate compound (B-2), and an organic acid anhydride (B-3),
The acidic phosphate compound (B-2) is at least one selected from the group consisting of acidic phosphate compounds represented by the following chemical formulas (I), (II), and (III),
The organic acid (B-1) is an organic acid other than the acidic phosphate compound (B-2),
The polyurethane prepolymer (A) is characterized by being a prepolymer synthesized from a polyol and an isocyanate.

In the chemical formula (I),
R ¹ and R ² are each a hydrogen atom, a hydrocarbon group or an aryl group;
R ¹ and R ² may be the same or different,
At least one of R ¹ and R ² is a hydrocarbon group or an aryl group.

In the chemical formulas (II) and (III),
R ³ and R ⁴ are each a hydrogen atom, a hydrocarbon group or an aryl group,
R ³ and R ⁴ may be the same or different,
at least one of R ³ and R ⁴ is a hydrocarbon group or an aryl group;
AO is an alkylene oxide group, each AO may be the same or different,
n represents an integer of 1 or more, and each n may be the same or different.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet in which an adhesive layer is formed on at least one side of a base material, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive of the present invention. do.

The method for producing a pressure-sensitive adhesive sheet according to the present invention includes a coating step of applying the pressure-sensitive adhesive and the cross-linking agent of the present invention to the adhesive layer forming surface of the substrate on which the adhesive layer is formed, and the coating step. and a heating step of heating the pressure-sensitive adhesive and the cross-linking agent on the pressure-sensitive adhesive layer forming surface.

An image display device of the present invention is an image display device having an image display surface to which a protective sheet for the image display device is attached, wherein the protective sheet is the pressure-sensitive adhesive sheet of the present invention.

ADVANTAGE OF THE INVENTION According to the present invention, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a method for producing the pressure-sensitive adhesive sheet, and an image display device that can satisfy removability, wettability, and resistance to contamination of adherends under high temperature and high humidity conditions are provided. can do.

The present invention will now be described with reference to examples. However, the invention is not limited by the following description.

In the adhesive of the present invention, the organic acid (B-1) may be, for example, at least one of carboxylic acid and sulfonic acid.

In the adhesive of the present invention, the organic acid anhydride (B-3) may be, for example, at least one of a carboxylic acid anhydride and a sulfonic acid anhydride.

The pressure-sensitive adhesive of the present invention may, for example, further contain a cross-linking agent (C), and the cross-linking agent may be polyisocyanate or polyol.

In the pressure-sensitive adhesive of the present invention, for example, the prepolymer (A) may be a polyurethane polyol synthesized from a polyol and a polyisocyanate and having a plurality of hydroxyl groups.

In the pressure-sensitive adhesive of the present invention, for example, the prepolymer (A) may be a polyurethane polyisocyanate having multiple isocyanate groups.

In the pressure-sensitive adhesive of the present invention, the cross-linking agent (C) may be, for example, polyisocyanate. Also, the cross-linking agent (C) may be, for example, a polyol.

The pressure-sensitive adhesive of the present invention may be, for example, a pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer on at least one side of a substrate to produce a pressure-sensitive adhesive sheet. Further, the substrate may be, for example, a polyethylene terephthalate or polyolefin substrate.

In the present invention, "alkyl" includes, for example, linear or branched alkyl. The number of carbon atoms of the alkyl is not particularly limited, and is, for example, 1-30, preferably 1-18, 3-16 or 4-12. Examples of alkyl include, but are not limited to, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group and tert-butyl group, pentyl group, hexyl group and heptyl. group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group and the like. The same applies to groups and atomic groups (such as alkoxy groups) derived from alkyl groups. The same applies to groups containing alkyl groups in their structures (alkylamino groups, alkoxy groups, etc.) or groups derived from alkyl groups (haloalkyl groups, hydroxyalkyl groups, aminoalkyl groups, alkanoyl groups, etc.).

In the present invention, "alkenyl" includes, for example, linear or branched alkenyl. Examples of the alkenyl include those having one or more double bonds in the above alkyl. The number of carbon atoms in the alkenyl is not particularly limited, and is, for example, the same as the alkyl, preferably 2-12 or 2-8. Examples of alkenyl include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butadienyl, 3-methyl-2-butenyl and the like.

In the present invention, "alkynyl" includes, for example, linear or branched alkynyl. Examples of the alkynyl include those having one or more triple bonds in the above alkyl. The number of carbon atoms in the alkynyl is not particularly limited, and is, for example, the same as the alkyl, preferably 2-12 or 2-8. Examples of the alkynyl include ethynyl, propynyl, butynyl and the like. Said alkynyl may, for example, additionally have one or more double bonds.

In the present invention, "aromatic ring" includes, for example, aryl, heteroaryl and arylalkyl. In addition, the "cyclic structure" includes, for example, the aromatic ring, cycloalkyl, bridged cyclic hydrocarbon group, spiro hydrocarbon group, and cycloalkenyl.

In the present invention, "aryl" includes, for example, monocyclic aromatic hydrocarbon groups and polycyclic aromatic hydrocarbon groups. Examples of the monocyclic aromatic hydrocarbon group include phenyl. The polycyclic aromatic hydrocarbon group is, for example, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9- phenanthryl and the like. Preferable examples include phenyl, naphthyl such as 1-naphthyl and 2-naphthyl, and the like.

In the present invention, "heteroaryl" includes, for example, monocyclic aromatic heterocyclic groups and condensed aromatic heterocyclic groups. The heteroaryl is, for example, furyl (eg: 2-furyl), thienyl (eg: 2-thienyl), pyrrolyl (eg: 1-pyrrolyl), imidazolyl (eg: 1-imidazolyl), pyrazolyl (eg: 1-pyrazolyl) ), triazolyl (eg: 1,2,4-triazol-1-yl), tetrazolyl (eg: 1-tetrazolyl), oxazolyl (eg: 2-oxazolyl), isoxazolyl (eg: 3-isoxazolyl), thiazolyl (eg: 2-thiazolyl), thiadiazolyl, isothiazolyl (e.g. 3-isothiazolyl), pyridyl (e.g. 2-pyridyl), pyridazinyl (e.g. 3-pyridazinyl), pyrimidinyl (e.g. 2-pyrimidinyl), furazanyl (e.g. 3-furazanyl) ), pyrazinyl (e.g. 2-pyrazinyl), oxadiazolyl (e.g. 1,3,4-oxadiazol-2-yl), benzofuryl (e.g. 2-benzo[b]furyl), benzothienyl (e.g. 2- benzo[b]thienyl), benzimidazolyl (e.g. 1-benzimidazolyl), dibenzofuryl, benzoxazolyl, benzothiazolyl, quinoxalyl (e.g. 2-quinoxalinyl), cinnolinyl (e.g. 3-cinnolinyl), quinazolyl (e.g. 2 -quinazolinyl), quinolyl (e.g. 2-quinolyl), phthalazinyl (e.g. 1-phthalazinyl), isoquinolyl (e.g. 1-isoquinolyl), prill, pteridinyl (e.g. 2-pteridinyl), carbazolyl, phenanthridinyl, acridinyl (eg: 1-acridinyl), indolyl (eg: 1-indolyl), isoindolyl, phenazinyl (eg: 1-phenazinyl), phenothiazinyl (eg: 1-phenothiazinyl) and the like.

In the present invention, "cycloalkyl" is, for example, a cyclic saturated hydrocarbon group with, but not limited to, 3-24 or 3-15 carbon atoms. The cycloalkyl includes, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, a bridged cyclic hydrocarbon group, a spiro hydrocarbon group and the like, preferably cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. , a bridged cyclic hydrocarbon group, and the like.

In the present invention, the "bridged cyclic hydrocarbon group" includes, for example, bicyclo[2.1.0]pentyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl and bicyclo[3 .2.1]octyl, tricyclo[2.2.1.0]heptyl, bicyclo[3.3.1]nonane, 1-adamantyl, 2-adamantyl and the like.

In the present invention, the "spirohydrocarbon group" includes, for example, spiro[3.4]octyl.

In the present invention, "cycloalkenyl" includes, for example, cyclic unsaturated aliphatic hydrocarbon groups having, for example, 3-24 or 3-7 carbon atoms. Examples of the above groups include cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl and the like, preferably cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl and the like. Said cycloalkenyl also includes, for example, bridged cyclic hydrocarbon groups and spirohydrocarbon groups having unsaturated bonds in the ring.

In the present invention, "arylalkyl" includes, for example, benzyl, 2-phenethyl and naphthalenylmethyl, and "cycloalkylalkyl" includes, for example, cyclohexylmethyl, adamantylmethyl and the like, and "hydroxyalkyl ” includes, for example, hydroxymethyl and 2-hydroxyethyl, and the like.

In the present invention, the "substituent" or "further substituent" is not particularly limited, but examples include carboxy, halogen, halogenated alkyl (e.g. CF ₃ , CH ₂ CF ₃ , CH ₂ CCl ₃ ), Nitro, nitroso, cyano, alkyl (e.g. methyl, ethyl, isopropyl, tert-butyl), alkenyl (e.g. vinyl), alkynyl (e.g. ethynyl), cycloalkyl (e.g. cyclopropyl, adamantyl), cycloalkylalkyl (e.g. cyclopropyl, adamantyl) cyclohexylmethyl, adamantylmethyl), cycloalkenyl (e.g. cyclopropenyl), aryl (e.g. phenyl, naphthyl), arylalkyl (e.g. benzyl, phenethyl), heteroaryl (e.g. pyridyl, furyl), heteroarylalkyl (e.g. pyridylmethyl), heterocyclyl (e.g. piperidyl), heterocyclylalkyl (e.g. morpholylmethyl), alkoxy (e.g. methoxy, ethoxy, propoxy, butoxy), perfluoroalkyl (e.g. _CF3 ), halogenated alkoxy (e.g. CF3) OCF ₃ ), acyl, alkenyloxy (eg vinyloxy, allyloxy), aryloxy (eg phenyloxy), alkyloxycarbonyl (eg methoxycarbonyl, ethoxycarbonyl, tert-butoxycarbonyl), arylalkyloxy (eg benzyl oxy), amino[alkylamino (e.g. methylamino, ethylamino, dimethylamino), acylamino (e.g. acetylamino, benzoylamino), arylalkylamino (e.g. benzylamino, tritylamino), hydroxyamino), alkylamino Including alkyl (eg diethylaminomethyl), sulfamoyl, oxo and the like.

In the present invention, "alkoxy" includes, for example, the aforementioned alkyl-O- groups, and includes, for example, methoxy, ethoxy, n-propoxy, isopropoxy, and n-butoxy. Examples include methoxymethyl and the like, and "aminoalkyl" includes, for example, 2-aminoethyl and the like.

In the present invention, "acyl" is not particularly limited, but examples include formyl, acetyl, propionyl, isobutyryl, valeryl, isovaleryl, pivaloyl, hexanoyl, cyclohexanoyl, benzoyl, ethoxycarbonyl, and the like. The same applies to a group containing an acyl group in its structure (acyloxy group, alkanoyloxy group, etc.). In the present invention, the number of carbon atoms in the acyl group includes carbonyl carbon, and for example, an alkanoyl group (acyl group) having 1 carbon atom refers to a formyl group.

In the present invention, "halogen" refers to any halogen element, including fluorine, chlorine, bromine and iodine.

In the present invention, "perfluoroalkyl" is not particularly limited, but includes, for example, perfluoroalkyl groups derived from linear or branched alkyl groups having 1 to 30 carbon atoms. The "perfluoroalkyl" more specifically includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl , undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, and other groups. The same applies to a group containing a perfluoroalkyl group in its structure (perfluoroalkylsulfonyl group, perfluoroacyl group, etc.).

In the present invention, when the various groups described above are heterocycles or contain heterocycles, the "number of carbon atoms" also includes the number of heteroatoms that constitute the heterocycles.

In addition, in the present invention, when isomers exist in substituents and the like, any isomers may be used unless otherwise specified. For example, a "naphthyl group" may be a 1-naphthyl group or a 2-naphthyl group, and a "propyl group" may be an n-propyl group or an isopropyl group.

Further, as described above, the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on at least one side of a base material, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive of the present invention. It is characterized by The pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive sheet that is used as a protective sheet for the image display surface of an image display device by being attached to the image display surface.

As described above, the method for producing a pressure-sensitive adhesive sheet according to the present invention includes a coating step of applying the pressure-sensitive adhesive of the present invention to the pressure-sensitive adhesive layer forming surface of the base material on which the pressure-sensitive adhesive layer is formed; After the step, the method for producing the pressure-sensitive adhesive sheet of the present invention includes a heating step of heating the pressure-sensitive adhesive on the pressure-sensitive adhesive layer forming surface. In the coating step, when the pressure-sensitive adhesive of the present invention contains a prepolymer and does not contain a cross-linking agent, it is preferable to apply the pressure-sensitive adhesive of the present invention together with the cross-linking agent.

Further, as described above, the image display device of the present invention is an image display device in which a protective sheet for the image display device is attached to the image display surface, and the protective sheet is the pressure-sensitive adhesive sheet of the present invention. It is characterized by

Hereinafter, embodiments of the present invention will be described more specifically. However, the present invention is not limited to the following embodiments.

[1. Adhesive]
As described above, the adhesive of the present invention comprises a polyurethane prepolymer (A) (hereinafter sometimes referred to as "component (A)"), an organic acid (B-1), an acidic phosphate compound (B -2), and at least one selected from the group consisting of organic acid anhydrides (B-3) (hereinafter sometimes referred to as “component (B)”), and the acidic phosphate compound (B -2) is at least one selected from the group consisting of acidic phosphoric ester compounds represented by the following chemical formulas (I), (II), and (III), and the organic acid (B-1) is , an organic acid other than the acidic phosphate compound (B-2), and the polyurethane prepolymer (A) is a prepolymer synthesized from a polyol and an isocyanate.

[1-1. Polyurethane prepolymer (A)]
The polyurethane prepolymer (A) is, as described above, a prepolymer synthesized from a polyol and an isocyanate. Said isocyanate may be, for example, a polyisocyanate.

The polyurethane prepolymer (A) may be, for example, a polyurethane polyol synthesized from a polyol and a polyisocyanate. In the present invention, the term "polyurethane polyol" refers to a polyurethane prepolymer having a plurality of hydroxyl groups. In the present invention, the term "prepolymer" refers to a polymer in which polymerization or cross-linking has progressed halfway, and which is capable of further progressing polymerization or cross-linking. In the present invention, the term "polyurethane prepolymer" refers to a polyurethane that has been partially polymerized or crosslinked and that can be converted into a polyurethane that has been further polymerized or crosslinked. The above-mentioned "polyurethane prepolymer" can be converted into polyurethane, for example, by having a plurality of hydroxyl groups or isocyanate groups to further proceed with polymerization or cross-linking. In the present invention, unless otherwise specified, the term "polyurethane polyisocyanate" refers to a polyurethane that can be converted into a polyurethane by further polymerization or cross-linking by having a plurality of isocyanate groups (for example, at both ends of the molecule). It means prepolymer. In the present invention, "polyol" refers to an organic compound having a plurality (2 or 3 or more) of hydroxyl groups (preferably at least one of alcoholic hydroxyl groups and phenolic hydroxyl groups) in one molecule.

The content of the polyurethane polyol is not particularly limited, but may be, for example, 20 to 80% by mass, 30 to 70% by mass, or 40 to 60% by mass with respect to the total mass of the adhesive of the present invention.

Alternatively, in the adhesive of the present invention, the polyurethane prepolymer (A) may be a polyurethane polyisocyanate having a plurality of isocyanate groups. In the present invention, "polyisocyanate" is an organic compound having a plurality (2 or 3 or more) of isocyanate groups (also referred to as isocyanato groups), ie (-N=C=O), in one molecule (polyfunctional isocyanate). Say. The content of the polyurethane polyisocyanate having multiple isocyanate groups is not particularly limited, but is preferably 20 to 80% by mass, more preferably 40 to 60% by mass, based on the total mass of the adhesive of the present invention. The types and the like of the polyol and polyisocyanate will be described together with examples of the method for producing the pressure-sensitive adhesive of the present invention in "2. Production method for pressure-sensitive adhesive" below.

[1-2. Organic acid (B-1), acidic phosphate compound (B-2), and organic acid anhydride (B-3)]
As described above, the pressure-sensitive adhesive of the present invention is a group consisting of an organic acid (B-1), an acidic phosphoric acid ester compound (B-2), and an organic acid anhydride (B-3) as the component (B). including at least one selected from In the adhesive of the present invention, the organic acid (B-1) may be at least one of carboxylic acid and sulfonic acid, or may contain both, as described above.

Examples of the carboxylic acid in the organic acid (B-1) include aromatic carboxylic acid and aliphatic carboxylic acid. Moreover, aromatic sulfonic acid, aliphatic sulfonic acid, etc. are mentioned as said sulfonic acid. From the viewpoint of suppressing or preventing corrosion of the adhesive applicator or adhesive object of the present invention, it is preferable that the acidity of the component (B) (acid component) is not too strong. From this point of view, the organic acid (B-1) is preferably at least one of an aromatic carboxylic acid and an aromatic sulfonic acid. The aromatic carboxylic acid and aromatic sulfonic acid are not particularly limited, but include, for example, aromatic carboxylic acids and aromatic sulfonic acids represented by chemical formulas (IV) and (V) described below.

In the organic acid (B-1), the aliphatic carboxylic acid and the aliphatic sulfonic acid include, for example, an aliphatic carboxylic acid having a carboxy group or a sulfo group bonded to an aliphatic saturated or unsaturated hydrocarbon group, or an aliphatic group sulfonic acids. The aliphatic saturated or unsaturated hydrocarbon group may be linear or branched, and may or may not contain a cyclic structure. The aliphatic saturated or unsaturated hydrocarbon group may be, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, cycloalkyl group, bridged hydrocarbon group, spirohydrocarbon group, cycloalkenyl group, and the like. From the viewpoint of suppressing or preventing corrosion of the adhesive applicator or adhesive object of the present invention, it is preferable that the aliphatic carboxylic acid and the aliphatic sulfonic acid are not too acidic. From this viewpoint, the aliphatic saturated or unsaturated hydrocarbon group may have, for example, 3 or more, 6 or more, or 8 or more carbon atoms. The upper limit of the number of carbon atoms in the aliphatic saturated or unsaturated hydrocarbon group is preferably 18 or less, 14 or less, or 12 or less. Examples of the aliphatic carboxylic acid and the aliphatic sulfonic acid include propionic acid, n-hexanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, n-nonadecanoic acid, 3,5,5-trimethylhexanoic acid, and the like. monobasic acid, dibasic acids such as hexanedioic acid, octanedioic acid and decanedioic acid, 1-propanesulfonic acid, methanesulfonic acid and the like.

The organic acid (B-1) preferably contains an aromatic ring from the viewpoint of solubility in a solvent (e.g., toluene, etc.) during pressure-sensitive adhesive production. One is preferred. The aromatic carboxylic acid and aromatic sulfonic acid can be represented, for example, by the following chemical formula (IV).

前記化学式（IV）中、
Ａｒは、芳香環（アリール）または複素芳香環（ヘテロアリール）であり、単環でも縮合環でもよく、
Ｒ^１００は、カルボキシ基、またはスルホ基であり、１でも複数でもよく、複数の場合は同一でも異なっていてもよく、
Ａｒは、Ｒ^１００以外の任意の置換基を１または複数有していてもよく、有していなくてもよい。

In the chemical formula (IV),
Ar is an aromatic ring (aryl) or a heteroaromatic ring (heteroaryl), which may be monocyclic or condensed;
R ¹⁰⁰ is a carboxy group or a sulfo group, and may be one or more, and if there are more than one, they may be the same or different;
Ar may or may not have one or more substituents other than R ¹⁰⁰ .

In the chemical formula (IV), Ar includes, for example, a benzene ring, naphthalene ring, anthracene ring, pyridine ring and the like. In addition, examples of optional substituents other than R ¹⁰⁰ include saturated or unsaturated hydrocarbon groups. The saturated or unsaturated hydrocarbon group is, for example, an aliphatic saturated or unsaturated hydrocarbon group. The aliphatic saturated or unsaturated hydrocarbon group may be linear or branched, and may or may not contain a cyclic structure. The aliphatic saturated or unsaturated hydrocarbon group may have, for example, 1-18 carbon atoms. The aliphatic saturated or unsaturated hydrocarbon group may be, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, cycloalkyl group, bridged hydrocarbon group, spirohydrocarbon group, cycloalkenyl group, and the like.

Further, the organic acid (B-1) can be represented, for example, by the following chemical formula (V).

前記化学式（V）中、Ｒ^１００は、前記化学式（IV）と同じであり、
Ｒ^２００は、脂肪族飽和または不飽和炭化水素基であり、１でも複数でもよく、同一でも異なっていてもよい。前記飽和または不飽和炭化水素基は、例えば、前記化学式（IV）と同様である。

In the chemical formula (V), R ¹⁰⁰ is the same as in the chemical formula (IV),
R ²⁰⁰ is an aliphatic saturated or unsaturated hydrocarbon group, may be one or more, and may be the same or different. The saturated or unsaturated hydrocarbon group is, for example, the same as the chemical formula (IV).

In the chemical formulas (IV) and (V), the aromatic carboxylic acid represented by the chemical formula (IV) or (V) from the viewpoint of suppressing or preventing corrosion of the adhesive applicator or the object to be adhered of the present invention and the aromatic sulfonic acid should not be too acidic. From this point of view, and from the point of view of the solubility of the aromatic carboxylic acid and aromatic sulfonic acid represented by the chemical formula (IV) or (V) in a solvent (e.g., toluene, etc.), the aliphatic saturated or unsaturated hydrocarbon The number of carbon atoms in the group is preferably 1 or more, 2 or more, or 4 or more. The upper limit of the number of carbon atoms in the aliphatic saturated or unsaturated hydrocarbon group is preferably 18 or less and 14 or less. The organic acid (B-1) can be used in combination with organic acids represented by the chemical formulas (IV) and (V).

In the chemical formulas (IV) and (V), examples of the aromatic carboxylic acid include straight-chain or branched alkylbenzenecarboxylic acids (alkylbenzoic acids). Alternatively, branched alkylbenzenecarboxylic acid (alkylbenzoic acid) and the like can be mentioned. Specific examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, and pyromellitic acid. Examples of the aromatic sulfonic acid include linear or branched alkylbenzenesulfonic acids, such as linear or branched alkylbenzenesulfonic acids having 10 to 14 alkyl carbon atoms.

As described above, the acidic phosphate compound (B-2) is at least one selected from the group consisting of the acidic phosphate compounds represented by the chemical formulas (I), (II), and (III). is one. As described above, the acidic phosphate compound (B-2) can be used in combination with the acidic phosphate compounds represented by the chemical formulas (I), (II) and (III).

In the chemical formulas (I), (II) and (III), R ¹ , R ² , R ³ and R ⁴ are each a hydrogen atom, a hydrocarbon group or an aryl group, as described above. Examples of the hydrocarbon group include saturated or unsaturated hydrocarbon groups. The saturated or unsaturated hydrocarbon group is, for example, an aliphatic saturated or unsaturated hydrocarbon group. The aliphatic saturated or unsaturated hydrocarbon group may be linear or branched, and may or may not contain a cyclic structure. The aliphatic saturated or unsaturated hydrocarbon group may have, for example, 4-18, 4-14, 4-10 or 4-7 carbon atoms. The aliphatic saturated or unsaturated hydrocarbon group may be, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, cycloalkyl group, bridged hydrocarbon group, spirohydrocarbon group, cycloalkenyl group, and the like. As said aryl group, each above-mentioned aryl group is mentioned, for example.

In the chemical formulas (I), (II) and (III), AO is an alkylene oxide group as described above, and each AO may be the same or different. AO includes, for example, an ethylene oxide group, a propylene oxide group, and the like. Also, as described above, n represents an integer of 1 or more, and each n may be the same or different. n can be, for example, 1-10, or 1-6.

The organic acid anhydride (B-3) is not particularly limited, but examples thereof include aromatic carboxylic acid anhydrides, aliphatic carboxylic acid anhydrides, aromatic sulfonic acid anhydrides, and aliphatic sulfonic acid anhydrides. . In the aromatic carboxylic anhydride, the aliphatic carboxylic anhydride, the aromatic sulfonic anhydride and the aliphatic sulfonic anhydride, an aromatic carboxylic acid, an aliphatic carboxylic acid, an aromatic sulfonic acid and an aliphatic sulfonic acid may be, for example, the same as the aliphatic carboxylic acid, aromatic carboxylic acid, aromatic sulfonic acid and aliphatic sulfonic acid exemplified for the organic acid (B-1).

The organic acid anhydride (B-3) preferably contains an aromatic ring from the viewpoint of solubility in a solvent (e.g., toluene, etc.) during adhesive production. is preferably at least one of group sulfonic anhydrides. The aromatic carboxylic anhydride and the aromatic sulfonic anhydride can be represented, for example, by the following chemical formula (VI) or (VII).

In the chemical formula (VI),
R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ --),
Ar is an aromatic ring (aryl) or a heteroaromatic ring (heteroaryl), may be a single ring or a condensed ring, each Ar may be the same or different,
each Ar may or may not have one or more optional substituents;
Each Ar is further linked with one or more carboxylic anhydride groups (--CO--O--CO--) or sulfonic anhydride groups ( _--SO.sub.2 --O-- _SO.sub.2-- ) other than ^R.sub.1000 . may or may not be connected.

In the chemical formula (VII),
R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ --),
Ar is an aromatic ring (aryl) or a heteroaromatic ring (heteroaryl), which may be monocyclic or condensed;
Ar may or may not have one or more optional substituents,
Ar may further have one or more carboxylic anhydride groups (--CO--O--CO--) or sulfonic anhydride groups ( _--SO.sub.2 --O-- _SO.sub.2-- ) other than ^R.sub.1000 . May or may not have.

In the chemical formulas (VI) and (VII), Ar is, for example, a benzene ring, naphthalene ring, anthracene ring, pyridine ring, etc., in the same manner as in the chemical formula (IV) exemplified for the organic acid (B-1). be done. Further, examples of the optional substituent include saturated or unsaturated hydrocarbon groups, as in the chemical formula (IV) exemplified for the organic acid (B-1). The saturated or unsaturated hydrocarbon group is, for example, an aliphatic saturated or unsaturated hydrocarbon group. The aliphatic saturated or unsaturated hydrocarbon group may be linear or branched, and may or may not contain a cyclic structure. The aliphatic saturated or unsaturated hydrocarbon group may have, for example, 1-18 carbon atoms. The aliphatic saturated or unsaturated hydrocarbon group may be, for example, the aforementioned alkyl group, alkenyl group, alkynyl group, cycloalkyl group, bridged hydrocarbon group, spirohydrocarbon group, cycloalkenyl group, and the like.

In the chemical formula (VI), when R ¹⁰⁰⁰ is a carboxylic anhydride group (-CO-O-CO-), it is represented by the following chemical formula (VI-1), and R ¹⁰⁰⁰ is a sulfonic anhydride group. (--SO ₂ --O--SO ₂ --) is represented by the following chemical formula (VI-2). In the following chemical formulas (VI-1) and (VI-2), R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ as shown below. -) is the same as the above chemical formula (VI).

Further, in the chemical formula (VII), when R ¹⁰⁰⁰ is a carboxylic anhydride group (-CO-O-CO-), it is represented by the following chemical formula (VII-1), where R ¹⁰⁰⁰ is a sulfonic anhydride group (--SO ₂ --O--SO ₂ --) is represented by the following chemical formula (VII-2). In the following chemical formulas (VII-1) and (VII-2), R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ as shown below. -), it is the same as the chemical formula (VII).

In addition, in the organic acid anhydride (B-3), the aromatic carboxylic acid anhydride and aromatic sulfonic acid anhydride can be represented by the following chemical formula (VIII) or (IX), for example.

In the chemical formula (VIII),
R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ --),
Each R ²⁰⁰ is an aliphatic saturated or unsaturated hydrocarbon group, each R ²⁰⁰ attached to each benzene ring may be one, plural or absent, and each R ²⁰⁰ may be the same when plural. may be different,
Each benzene ring is further linked by one or more carboxylic anhydride groups (--CO--O--CO--) or sulfonic anhydride groups ( _--SO.sub.2 --O-- _SO.sub.2-- ) other than ^R.sub.1000 . may or may not be connected.
In each R ²⁰⁰ , the saturated or unsaturated hydrocarbon group is, for example, the same as in the chemical formulas (IV) and (V).

In the chemical formula (IX),
R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ --),
R ²⁰⁰ is an aliphatic saturated or unsaturated hydrocarbon group, R ²⁰⁰ bonded to a benzene ring may be 1, plural or absent, and R ²⁰⁰ may be the same or different when plural Often,
The benzene ring further has one or more carboxylic anhydride groups (--CO--O--CO--) or sulfonic anhydride groups ( _--SO.sub.2 --O-- _SO.sub.2-- ) other than ^R.sub.1000 ; may or may not have.
In addition, in R ²⁰⁰ , the saturated or unsaturated hydrocarbon group is, for example, the same as in the chemical formulas (IV) and (V).

In the chemical formula (VIII), when R ¹⁰⁰⁰ is a carboxylic anhydride group (-CO-O-CO-), it is represented by the following chemical formula (VIII-1), where R ¹⁰⁰⁰ is a sulfonic anhydride group. (--SO ₂ --O--SO ₂ --) is represented by the following chemical formula (VIII-2). In the following chemical formulas (VIII-1) and (VIII-2), R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--) or a sulfonic anhydride group (--SO ₂ --O--SO ₂ as shown below. -), it is the same as the chemical formula (VIII).

In the chemical formula (IX), when R ¹⁰⁰⁰ is a carboxylic anhydride group (--CO--O--CO--), it is represented by the following chemical formula (IX-1), where R ¹⁰⁰⁰ is a sulfonic anhydride group. (--SO ₂ --O--SO ₂ --) is represented by the following chemical formula (IX-2). In the following chemical formulas (IX-1) and (IX-2), R ¹⁰⁰⁰ is a carboxylic anhydride group (—CO—O—CO—) or a sulfonic anhydride group (—SO ₂ —O—SO ₂ as shown below. -), it is the same as the above chemical formula (IX).

In the chemical formulas (VI) to (IX), the aromatic carboxylic acids represented by the chemical formulas (VI) to (IX) are used from the viewpoint of suppressing or preventing corrosion of the adhesive applicator or adhesive object of the present invention. and the aromatic sulfonic acid should not be too acidic. From this point of view, and from the point of view of the solubility of the aromatic carboxylic acid anhydride or aromatic sulfonic acid anhydride represented by the chemical formulas (VI) to (IX) in a solvent (for example, toluene), the aliphatic saturated or The unsaturated hydrocarbon group preferably has 1 or more, 2 or more, or 4 or more carbon atoms. The upper limit of the number of carbon atoms in the aliphatic saturated or unsaturated hydrocarbon group is preferably 18 or less and 14 or less.

In the chemical formulas (VI) to (IX), examples of the aromatic carboxylic acid include straight-chain or branched alkylbenzenecarboxylic acids (alkylbenzoic acids). Alternatively, branched alkylbenzenecarboxylic acid (alkylbenzoic acid) and the like can be mentioned. Further, specific examples of the aromatic carboxylic anhydride include benzoic anhydride, phthalic anhydride, and pyromellitic anhydride.

As described above, from the viewpoint of suppressing or preventing corrosion of the adhesive applicator or adhesive object of the present invention, it is preferable that the acidity of component (B) (acid component) is not too strong. From this point of view, in the present invention, as described above, the component (B) (acid component) includes the organic acid (B-1), the acidic phosphoric acid ester compound (B-2), and the organic acid anhydride (B -3), and more preferably an acidic phosphoric acid ester compound (B-2) or an organic acid anhydride (B-3). In addition, from the viewpoint of suppressing or preventing corrosion of the adhesive application device or application object of the present invention, the organic acid anhydride (B-3) is preferably a carboxylic acid anhydride.

The content of component (B) (acid component) is not particularly limited, but is, for example, 0.3 to 6% by mass, 0.6 to 6% by mass, or 3 to 6% by mass, based on the total mass of the adhesive of the present invention. It may be 6% by mass. Further, the content of the component (B) (acid component) is, for example, 0.5 to 10% by mass, 1 to 10% by mass, or 5 to 10% by mass, relative to the total mass of the polyurethane prepolymer (A). It may be 10% by mass. From the viewpoint of resistance to contamination of adherends under high temperature and high humidity conditions, it is preferable that the content of component (B) (acid component) is not too low. Moreover, from the viewpoint of removability and from the viewpoint of suppressing or preventing corrosion of an application device or an application target, it is preferable that the content of component (B) (acid component) is not too high.

[1-3. Crosslinking agent (C)]
The pressure-sensitive adhesive of the present invention may further contain a cross-linking agent (C), as described above. The cross-linking agent (C) is not particularly limited, but when the polyurethane prepolymer (A) is a polyurethane polyol, part or all of the cross-linking agent (C) is preferably polyisocyanate. In the present invention, as described above, "polyisocyanate" is an organic compound having a plurality (2 or 3 or more) of isocyanate groups (also referred to as isocyanato groups), that is, (-N=C=O) in one molecule ( polyfunctional isocyanate).

When the pressure-sensitive adhesive of the present invention contains the polyisocyanate as the cross-linking agent (C), the content thereof is not particularly limited. It may be from 0.5 to 5 times or from 1 to 4 times the molar amount.

When the cross-linking agent (C) contains a polyisocyanate (polyfunctional isocyanate), the polyisocyanate is not particularly limited. The polyisocyanate may be, for example, the same as the polyisocyanate used for synthesizing the polyurethane prepolymer (A), which is exemplified in "2. Production method of pressure-sensitive adhesive" described later. It may be a biuret form reacted with water, a trimer having an isocyanurate ring, or the like, and may be used alone or in combination of multiple types.

Alternatively, in the pressure-sensitive adhesive of the present invention, the polyurethane prepolymer (A) may be a polyurethane polyisocyanate having a plurality of isocyanate groups, as described above. In this case, part or all of the cross-linking agent (C) is preferably a polyol. When the pressure-sensitive adhesive of the present invention contains the polyol as the cross-linking agent (C), the content is not particularly limited, but the hydroxyl group of the polyol should be 0.00 per mole of the isocyanate groups of the polyurethane polyisocyanate. It may be 5-5 times or 1-4 times the molar amount.

When the cross-linking agent (C) contains a polyol, the polyol is not particularly limited. The polyol may be, for example, the same as the polyol used for synthesizing the polyurethane prepolymer (A), which will be exemplified in "2. Production method of pressure-sensitive adhesive" described later. good.

[1-4. Other ingredients]
The adhesive of the present invention contains the components (A) and (B) as described above. The component (C) (crosslinking agent (C)) may or may not be included as described above. In addition, the adhesive of the present invention may or may not contain components other than the components (A) to (C). For example, the pressure-sensitive adhesive of the present invention further contains a solvent, an antioxidant, an anti-crosslinking agent, a filler, a coloring agent, an ultraviolet absorber, an antifoaming agent, a light stabilizer, an antistatic agent, etc., as the other components. It may or may not be included. Although the types thereof are not particularly limited, for example, they may be the same as or similar to general pressure-sensitive adhesives. Examples of the ultraviolet absorber include, but are not particularly limited to, benzophenone-based, benzotriazole-based, and triazine-based ultraviolet absorbers. Examples of the antifoaming agent include, but are not particularly limited to, silicone antifoaming agents and mineral oil antifoaming agents. The light stabilizer is not particularly limited, but includes, for example, hindered amine-based light stabilizers. Examples of the antistatic agent include ionic compounds such as inorganic salts and organic salts, and nonionic compounds such as nonionic surfactants. The solvent, the antioxidant and the cross-linking inhibitor are not particularly limited. be.

As said other component, carboxylic acid ester etc. may be included, for example. The carboxylic acid ester is not particularly limited, but may be, for example, the carboxylic acid esters described in JP-A-2011-190420, JP-A-2015-151429, and JP-A-2016-186029. The carboxylic acid ester may be, for example, a carboxylic acid ester in Examples described later.

[2. Method for manufacturing adhesive]
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited except that the components (A) and (B) are used. Reference 1 and the like may be used as a reference. Hereinafter, the production method in the case where the polyurethane prepolymer (A) is a polyurethane polyol (polyurethane prepolymer) synthesized from a polyol and a polyisocyanate will be mainly described with examples.

First, a reaction vessel is charged with a polyol, a polyisocyanate, a solvent, and, if necessary, a catalyst, and the reaction is carried out while heating and stirring. The amount of the polyol used is not particularly limited, but is, for example, 20 to 80% by mass, or 40 to 60% by mass, based on the mass of the pressure-sensitive adhesive after production. The amount of the polyisocyanate used is not particularly limited, but is, for example, 0.5 to 10% by mass, or 1 to 5% by mass, based on the mass of the pressure-sensitive adhesive after production. The amount of the solvent used is not particularly limited, but is, for example, 10 to 50% by mass, or 20 to 40% by mass, based on the mass of the pressure-sensitive adhesive after production. The catalyst may not be used, but is preferably used from the viewpoint of smooth progress of the reaction. When the catalyst is used, the amount used is not particularly limited, but is, for example, 0.001 to 0.1% by mass based on the mass of the pressure-sensitive adhesive after production. The reaction temperature for the above reaction is not particularly limited, but is, for example, 30 to 80°C or 40 to 60°C. The reaction time for the reaction is not particularly limited, but is, for example, 0.5 to 15 hours, 0.5 to 4 hours, or 1 to 3 hours. In this manner, a polyurethane polyol (polyurethane prepolymer (A))-containing composition can be synthesized.

In addition, in the synthesis of the polyurethane polyol-containing composition, for example, (1) a method of charging a polyester polyol, a polyether polyol, a catalyst, and a polyisocyanate into a volumetric flask, and (2) a method of charging a polyester polyol, a polyether polyol, and a catalyst. A method of charging a flask and adding the polyisocyanate dropwise is also possible. (1) is simpler, but (2) is easier to control the reaction, so it is possible to use them properly according to need.

Furthermore, the component (B) is added to the synthesized polyurethane polyol-containing composition and stirred until uniform. At this time, if necessary, component (C) (crosslinking agent (C)) may be added. Further, if necessary, other components than components (A) to (C) may be added. The other component may contain, for example, a solvent, and may contain an antioxidant, an anti-crosslinking agent, a carboxylic acid ester, etc., as described above. Thus, the adhesive of the present invention can be obtained.

The cross-linking agent (C) preferably contains, for example, polyisocyanate (polyfunctional isocyanate). The polyisocyanate is not particularly limited, but may be the same as the polyisocyanate used for synthesizing the polyurethane polyol (polyurethane prepolymer (A))-containing composition exemplified below. , water-reacted burettes, trimers having an isocyanurate ring, etc., may be used alone or in combination of a plurality of types. In the cross-linking agent (C), the amount of the polyisocyanate to be used is not particularly limited. Four times the molar amount, or 0.5 to 5 times or 1 to 4 times the molar amount of the hydroxyl groups of the polyol relative to the molar amount of the isocyanate groups of the polyurethane polyisocyanate is preferred.

Although the solvent may not be used, it is preferable to use it from the viewpoint of smooth mixing of the components constituting the pressure-sensitive adhesive of the present invention. When the catalyst is used, the amount used is not particularly limited, but is, for example, 0.001 to 0.1% by mass, or 0.01 to 0.05% by mass, based on the mass of the pressure-sensitive adhesive after production. . Although the antioxidant may not be used, it is preferable to use it. When the antioxidant is used, the amount used is not particularly limited, but is, for example, 0.05 to 1% by mass, or 0.1 to 0.6% by mass, based on the mass of the pressure-sensitive adhesive after production. . When the fatty acid ester is used, the amount used is not particularly limited, but is, for example, 5 to 50% by mass, or 10 to 30% by mass, based on the mass of the pressure-sensitive adhesive after production.

The synthesis of the polyurethane polyol (polyurethane prepolymer (A))-containing composition will be described in more detail below.

The polyol is not particularly limited, and may be, for example, bifunctional (having two hydroxyl groups in one molecule) or trifunctional or higher (having three or more hydroxyl groups in one molecule), but should be trifunctional or higher. is preferred, and trifunctional is particularly preferred. Further, the polyol may be used alone or in combination of multiple types. The polyol is not particularly limited, but may be, for example, one or both of a polyester polyol and a polyether polyol.

The polyester polyol is not particularly limited, and may be, for example, a known polyester polyol. Examples of the acid component of the polyester polyol include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of the glycol component of the polyester polyol include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, poly oxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol and the like. Examples of the polyol component of the polyester polyol include glycerin, trimethylolpropane, and pentaerythritol. Other examples include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone) and polyvalerolactone.

The molecular weight of the polyester polyol is not particularly limited, and a range from low molecular weight to high molecular weight can be used. A polyester polyol having a number average molecular weight of 500 to 5,000 is preferably used. If the number average molecular weight is 500 or more, it is easy to prevent gelation due to too high reactivity. Moreover, if the number average molecular weight is 5,000 or less, it is easy to prevent a decrease in reactivity and a decrease in the cohesive strength of the polyurethane polyol itself. The polyester polyol may or may not be used, but when used, the amount used is, for example, 10 to 90 mol%, or 10 to 50 mol% of the polyol constituting the polyurethane polyol. good too.

Moreover, the polyether polyol is not particularly limited, and may be, for example, a known polyether polyol. Specifically, the polyether polyol is prepared by using a low-molecular-weight polyol such as water, propylene glycol, ethylene glycol, glycerin, and trimethylolpropane as an initiator, and an oxirane such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran. It may be a polyether polyol obtained by polymerizing a compound. More specifically, the polyether polyol may have two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol. The molecular weight of the polyether polyol is not particularly limited, and can be used from low molecular weight to high molecular weight. For example, polyether polyols having number average molecular weights of 1,000 to 15,000 may be used. If the number average molecular weight is 1,000 or more, it is easy to prevent gelation due to too high reactivity. Further, when the molecular weight is 15,000 or less, it is easy to prevent a decrease in reactivity and a decrease in the cohesive strength of the polyurethane polyol itself. The polyether polyol may or may not be used, but when used, the amount used is, for example, 20 to 100 mol %, or 20 to 80 mol % of the polyols constituting the polyurethane polyol. may

Part of the polyether polyol, if necessary, is ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, glycols such as pentaerythritol, ethylenediamine, N - Polyvalent amines such as aminoethylethanolamine, isophoronediamine, and xylylenediamine may be substituted and used in combination.

As described above, the polyol may be a bifunctional (having two hydroxyl groups in one molecule) polyether polyol, but is preferably trifunctional or higher (having three or more hydroxyl groups in one molecule). In particular, by using a polyol having a number average molecular weight of 1,000 to 15,000 and having a trifunctional or more function, in part or in whole, it becomes easier to balance adhesive strength and removability. When the number average molecular weight is 1,000 or more, it is easy to prevent gelation due to excessively high reactivity of the trifunctional or higher polyol. Further, when the number average molecular weight is 15,000 or less, it is easy to prevent a decrease in the reactivity of the tri- or higher functional polyol and a decrease in the cohesive strength of the polyurethane polyol itself. For example, a trifunctional or higher polyol having a number average molecular weight of 2,500 to 3,500 may be used partially or wholly.

Examples of the polyisocyanate (organic polyisocyanate compound) include, but are not limited to, known aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. In addition, one type of polyisocyanate may be used alone, or a plurality of types may be used in combination.

Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanatobenzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4' , 4″-triphenylmethane triisocyanate and the like.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and 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, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, etc. mentioned.

In addition, a trimethylolpropane adduct of the above polyisocyanate, a water-reacted biuret, a trimer having an isocyanurate ring, and the like can also be used in combination.

As the polyisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) and the like are preferable.

The catalyst is not particularly limited, and for example, a known catalyst can be used. Examples of the catalyst include tertiary amine compounds and organometallic compounds.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU) and the like.

Examples of the organometallic compounds include tin-based compounds and non-tin-based compounds. Examples of the tin-based compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate and the like. Examples of the non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate and butoxy titanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate and lead naphthenate; Iron-based such as iron 2-ethylhexanoate and iron acetylacetonate, cobalt-based such as cobalt benzoate and cobalt 2-ethylhexanoate, zinc-based such as zinc naphthenate and zinc 2-ethylhexanoate, zirconium naphthenate, etc. is mentioned.

When these catalysts are used, for example, in a system in which two kinds of polyols, polyester polyol and polyether polyol, exist, the difference in reactivity causes gelation or turbidity of the reaction solution in a single catalyst system. is likely to occur. In such a case, for example, by using two or more kinds of catalysts together, the reaction rate, the selectivity of the catalyst, etc. can be controlled, and these problems can be solved. Examples of the combination include tertiary amine/organometallic, tin/non-tin, tin/tin, etc., preferably tin/tin, more preferably dibutyltin dilaurate and 2- It is a combination of tin ethylhexanoate. The compounding ratio is not particularly limited, but for example, the mass of tin 2-ethylhexanoate/dibutyltin dilaurate is less than 1, and may be, for example, 0.2 to 0.6. If the compounding ratio is less than 1, it is easy to prevent gelation due to the balance of catalytic activity. The amount of these catalysts used is not particularly limited, but is, for example, 0.01 to 1.0% by mass or 0.01 to 0.2% by mass based on the total amount of polyol and organic polyisocyanate.

When using the catalyst, the reaction temperature for synthesizing the polyurethane polyol may be, for example, below 100°C, or between 40°C and 60°C. If the temperature is less than 100°C, it is easy to control the reaction rate and the crosslinked structure, and it is easy to obtain a polyurethane polyol having a predetermined molecular weight.

Moreover, when the catalyst is not used (no catalyst), the reaction temperature for synthesizing the polyurethane polyol may be, for example, 100° C. or higher, or 110° C. or higher. In addition, the reaction time for synthesizing the polyurethane polyol is, for example, 3 hours or more in the absence of a catalyst.

The solvent used for synthesizing the polyurethane polyol is not particularly limited, and for example, known solvents can be used. Examples of the solvent include ketones such as methyl ethyl ketone, acetone and methyl isobutyl ketone, esters such as ethyl acetate, n-butyl acetate and isobutyl acetate, and hydrocarbons such as toluene and xylene. Toluene is particularly preferred in view of the solubility of polyurethane polyol, the boiling point of the solvent, and the like.

Moreover, the antioxidant is not particularly limited, but examples thereof include phenol-based and sulfur-based antioxidants.

Moreover, in the pressure-sensitive adhesive of the present invention, there is no particular limitation on the production method when the polyurethane prepolymer (A) contains a polyurethane polyisocyanate having a plurality of isocyanate groups. Specifically, for example, except that the amount of polyisocyanate used is relatively increased to leave isocyanate groups in the prepolymer, the above-described production method (the pressure-sensitive adhesive of the present invention includes the carboxylic acid ester, the polyol and It can be carried out in the same manner as in the case of containing polyurethane polyol (polyurethane prepolymer) synthesized from polyisocyanate). In this case, the amount of the polyol used is not particularly limited, but is, for example, 30 to 70% by mass, or 40 to 60% by mass, based on the mass of the pressure-sensitive adhesive after production. The amount of the polyisocyanate used is not particularly limited, but is, for example, 3 to 20% by mass, or 5 to 15% by mass, based on the mass of the pressure-sensitive adhesive after production. The amount of other components (solvent, catalyst, antioxidant, anti-crosslinking agent, etc.) may be the same as in the production method described above, for example. Moreover, in this case, the cross-linking agent (C) preferably contains a polyol as described above. The amount of the polyol used in the cross-linking agent (C) is not particularly limited, but for example, the amount of hydroxyl groups in the polyol is 0.5 to 5 times or 1 to 4 times the molar amount of isocyanate groups in the polyurethane polyisocyanate. or 0.5 to 5 times or 1 to 4 times the molar amount of the hydroxyl groups of the polyol relative to the molar amount of the isocyanate groups of the polyurethane polyisocyanate.

In the present invention, the molecular weight, molecular weight dispersity, etc. of the polyurethane prepolymer (A) are not particularly limited. The number average molecular weight of the polyurethane prepolymer is determined by the respective molecular weights of the polyisocyanate and polyol used as raw materials for producing the polyurethane prepolymer, and the reaction ratio (NCO/OH equivalent ratio) between the polyisocyanate and the polyol. It can be calculated theoretically (Japanese Patent Application Laid-Open No. 2017-025147).

[3. Adhesive sheet and its manufacturing method, use, etc.]
Next, the pressure-sensitive adhesive sheet of the present invention, its production method, uses, etc. will be described with reference to examples.

As described above, the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on at least one side of a substrate, and the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive of the present invention. It is characterized by The production method thereof is not particularly limited, but for example, it can be produced by the production method of the present invention (the production method of the pressure-sensitive adhesive sheet of the present invention).

As described above, the production method of the present invention (the method of producing an adhesive sheet according to the present invention) includes applying the adhesive of the present invention to the adhesive layer forming surface of the base material on which the adhesive layer is formed. The method for producing the pressure-sensitive adhesive sheet of the present invention, comprising a coating step, and a heating step of heating the pressure-sensitive adhesive on the pressure-sensitive adhesive layer-forming surface after the coating step. Hereinafter, the method for producing a pressure-sensitive adhesive sheet according to the present invention will be mainly described with reference to examples when the polyurethane prepolymer (A) contains a polyurethane polyol synthesized from a polyol and a polyisocyanate.

That is, first, the pressure-sensitive adhesive of the present invention is applied to the surface of the substrate on which the pressure-sensitive adhesive layer is to be formed (coating step). The base material is not particularly limited, and examples thereof include plastics, polyurethanes, papers, and metal foils, with plastics being preferred. Examples of the plastic include PET (polyethylene terephthalate), PE (polyethylene), PP (polypropylene), PC (polycarbonate), and the like.

The shape of the substrate is also not particularly limited, and examples thereof include sheets, films, foams, and the like. The substrate is preferably in the form of a long tape that can be taken up, for example, from the standpoint of ease of handling and storage of the pressure-sensitive adhesive sheet after production.

Further, the substrate may be, for example, a substrate having an adhesive layer-forming surface of the substrate subjected to an easy-adhesion treatment, if necessary. The adhesion-facilitating treatment is not particularly limited, but specific examples thereof include a method of treating corona discharge, a method of applying an anchor coating agent, and the like.

When the adhesive of the present invention does not contain the cross-linking agent (C), it is preferable to mix the cross-linking agent (C) prior to the coating step, for example. When the cross-linking agent (C) contains a polyisocyanate, the polyisocyanate is not particularly limited, but the polyisocyanate exemplified in "2. Production method of pressure-sensitive adhesive", and the trimethylolpropane adduct, reacting with water and a trimer having an isocyanurate ring. When the cross-linking agent (C) contains a polyol, the polyol is not particularly limited. The polyol may be, for example, the same as the polyol used for synthesizing the polyurethane prepolymer (A) exemplified in the above-mentioned "2. Production method of pressure-sensitive adhesive", and may be used alone or in combination of multiple types. good. Moreover, the usage amount of the cross-linking agent (C) is, for example, as described above. Furthermore, for the purpose of facilitating mixing of the pressure-sensitive adhesive of the present invention and the cross-linking agent, or facilitating coating on the substrate, a solvent may be further mixed prior to the coating step. The type and the like of the solvent are not particularly limited, but are, for example, the same as the solvents exemplified in "2. Production method of pressure-sensitive adhesive", and may be used alone or in combination of multiple types.

The coating method in the coating step is not particularly limited, and may be a known method. Examples of the coating method include roll coater method, comma coater method, die coater method, reverse coater method, silk screen method, gravure coater method and the like.

In addition, the coating amount (coating amount) of the adhesive in the coating step is not particularly limited, but the thickness of the adhesive layer in the adhesive sheet to be produced is, for example, 1 to 50 μm, 5 to 30 μm, 7 to 20 μm. , or 10 to 15 μm.

Furthermore, after the coating step, the adhesive is heated on the adhesive layer forming surface (heating step). In addition, hereinafter, the heating process may be referred to as a "first heating process" in order to distinguish it from a second heating process described later. The heating temperature in the heating step (first heating step) is not particularly limited. Or it is 130° C. or higher. Although the upper limit of the heating temperature is not particularly limited, it is, for example, 150° C. or less.

In order to prevent the adhesive layer from protruding from the edge of the substrate during storage, handling, etc. of the adhesive sheet, it is preferable to raise the heating temperature in the heating step as high as possible. By making the heating temperature as high as possible, for example, the cross-linking (curing) reaction between the pressure-sensitive adhesive of the present invention and the cross-linking agent is sufficiently facilitated, so it is presumed that the protrusion can be prevented. However, this mechanism is speculation and does not limit the present invention.

As described above, with a typical adhesive, if the heating temperature after applying the adhesive to the substrate is too high, the adhesion of the adhesive layer to the substrate may decrease. However, according to the pressure-sensitive adhesive of the present invention, even when heated at a high temperature, the adhesiveness to the base material is good, and as described above, repelling and protrusion to the base material can be prevented.

In addition, the heating time in the heating step (first heating step) is not particularly limited. A time that does not cause damage is preferable. The specific heating time is, for example, 30 to 240 seconds or 60 to 180 seconds, depending on the types of the solvent and the base material.

Furthermore, the method for producing a pressure-sensitive adhesive sheet according to the present invention preferably includes a second heating step of heating at a temperature lower than that of the heating step after the heating step (first heating step). The second heating step may or may not be performed, but by performing this step, the protrusion of the adhesive layer from the edge of the base material can be more effectively prevented. Although the phenomenon that occurs in the second heating step is unknown, it is presumed that, for example, curing (crosslinking) of the adhesive layer further progresses. However, this guess does not limit the present invention. The heating temperature in the second heating step is not particularly limited, but is, for example, 30 to 50°C or 35 to 45°C. Moreover, the heating time in the second heating step is not particularly limited, but is, for example, 24 to 120 hours, or 48 to 96 hours.

The use of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but as described above, it is preferably used as a protective sheet for the image display surface of an image display device by being attached to the image display surface. Moreover, when using for this purpose, for example, it is more preferable that the base material is transparent.

As described above, the image display device of the present invention is an image display device in which a protective sheet for the image display device is attached to the image display surface, and the protective sheet is the pressure-sensitive adhesive sheet of the present invention. Characterized by Examples of the image display device include, but are not limited to, mobile phones, smart phones, tablet computers, and the like. However, the application of the pressure-sensitive adhesive sheet of the present invention is not limited to image display devices, and can be used, for example, as a protective sheet for window glass of automobiles, buildings, and the like. The pressure-sensitive adhesive sheet of the present invention is not limited to glass, and can be used as a protective sheet for ITO (Indium Tin Oxide) processed on a glass substrate as a transparent conductive film. Furthermore, the use of the pressure-sensitive adhesive sheet of the present invention is not limited to these, and for example, it can be widely used in the same applications as general pressure-sensitive adhesive sheets, pressure-sensitive adhesive films, pressure-sensitive adhesive tapes, and the like. Further, the application of the pressure-sensitive adhesive of the present invention is not particularly limited to the pressure-sensitive adhesive sheet of the present invention, and for example, it can be widely used in the same applications as the pressure-sensitive adhesive.

The form of the pressure-sensitive adhesive sheet of the present invention is also not particularly limited. It is preferable to peel off the separator. Further, for example, the pressure-sensitive adhesive sheet of the present invention is in the form of a long tape that can be taken up, and is preferably taken up and stored. According to the adhesive tape of the present invention, it is possible to prevent the adhesive layer from protruding from the edge of the adhesive tape during winding, storage, and the like.

Examples of the present invention will be described below. However, the present invention is not limited to these examples.

Raw material names (compound names), product names (trade names), and manufacturers used in the following examples and comparative examples are shown in Table 1 below.

[Synthesis Example 1]
A polyurethane prepolymer (A) was synthesized according to the following procedure.
Glycerin PO·EO, hexamethylene diisocyanate, toluene, and DBTDL were introduced into a separable flask equipped with a stirrer, a reflux condenser, and a thermometer, and reacted at 60° C. for 3 hours while stirring. When the NCO groups in the contents were measured using an infrared spectrophotometer (IR), residual NCO groups could not be confirmed. The contents were then cooled to below 40°C and antioxidant and ethyl acetate were added. "Glycerin PO.EO" represents propylene oxide and ethylene oxide adducts of glycerin. "DBTDL" stands for dibutyltin dilaurate.

[Synthesis Example 2]
A polyurethane prepolymer (A) was synthesized in the same manner as in Synthesis Example 1, except that glycerin PO.EO in Synthesis Example 1 was replaced with glycerin PO. "Glycerin PO" represents a propylene oxide adduct of glycerin.

[Synthesis Example 3]
A polyurethane prepolymer (A) was synthesized in the same manner as in Synthesis Example 1, except that the glycerin PO.EO of Synthesis Example 1 and the pluronic-type polyol were used in combination. "Pluronic-type polyol" represents an ethylene oxide adduct of polypropylene glycol.

[Synthesis Example 4]
A polyurethane prepolymer (A) was synthesized in the same manner as in Synthesis Example 1 except that glycerin PO.EO and polypropylene glycol in Synthesis Example 1 were used in combination.

[Synthesis Example 5]
A polyurethane prepolymer (A) was synthesized in the same manner as in Synthesis Example 1 except that hexamethylene diisocyanate in Synthesis Example 1 was changed to 4,4'-diphenylmethane diisocyanate.

The amount (parts by mass) of each component used in the synthesis of the polyurethane prepolymer (A) in Synthesis Examples 1 to 5 is summarized in Table 2 below. That is, in Synthesis Examples 1 to 5, a solution containing a polyurethane prepolymer (A) was obtained.

[Example 1]
To 100 parts by mass of the polyurethane prepolymer solution of Synthesis Example 1 (60 parts by mass as a solid content), 1 part by mass of linear alkylbenzene sulfonic acid as an organic acid and 8 parts by mass of a cross-linking agent N (polyisocyanate-based cross-linking agent manufactured by Lion Specialty Chemicals Co., Ltd.) The adhesive (coating liquid) of Example 1 was prepared by blending and stirring well.

[Example 2]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the polyurethane polyol was used in Synthesis Example 2.

[Example 3]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the polyol of polyurethane was used in Synthesis Example 3.

[Example 4]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the polyurethane polyol was used in Synthesis Example 4.

[Example 5]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the polyurethane polyol was Synthesis Example 5.

[Example 6]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that a branched alkylbenzenesulfonic acid was used as the organic acid.

[Example 7]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that an acidic phosphate compound JP-508 (manufactured by Johoku Chemical Industry Co., Ltd.) was used instead of the organic acid.

[Example 8]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that an acidic phosphate compound AP-8 (manufactured by Daihachi Chemical Industry Co., Ltd.) was used instead of the organic acid.

[Example 9]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that an acidic phosphate compound Phosphanol LP-700 (manufactured by Toho Chemical Industry Co., Ltd.) was used instead of the organic acid.

[Example 10]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 30 parts by mass of a carboxylic acid ester represented by the chemical formula (1001) (where n is 12 on average) was added.

[Example 11]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 30 parts by mass of a carboxylic acid ester represented by the chemical formula (1010) (where n is 10 on average) was added.

[Example 12]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the amount of linear alkylbenzenesulfonic acid was 0.6 parts by mass.

[Example 13]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the linear alkylbenzenesulfonic acid was 3.0 parts by mass.

[Example 14]
A pressure-sensitive adhesive was produced in the same manner as in Example 9 except that Phosphanol LP-700 (manufactured by Toho Chemical Industry Co., Ltd.) was 2.0 parts by mass.

[Example 15]
A pressure-sensitive adhesive was produced in the same manner as in Example 9 except that Phosphanol LP-700 (manufactured by Toho Chemical Industry Co., Ltd.) was 4.0 parts by mass.

[Example 16]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 2 parts by mass of an acidic phosphate compound JP-504 (manufactured by Johoku Chemical Industry Co., Ltd.) was used instead of the organic acid.

[Example 17]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that propionic acid was used as the organic acid.

[Example 18]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that n-nonadecanoic acid was used as the organic acid.

[Example 19]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 2 parts by mass of an acidic phosphate compound Phosphanol RB-410 (manufactured by Toho Chemical Industry Co., Ltd.) was used instead of the organic acid.

[Example 20]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 4 parts by mass of benzoic anhydride, which is an organic acid anhydride, was used instead of the organic acid, and 12 parts by mass of the cross-linking agent N was used.

[Example 21]
A pressure-sensitive adhesive was produced in the same manner as in Example 1 except that the organic acid anhydride, phthalic anhydride, was used instead of the organic acid.

[Example 22]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the amount of linear alkylbenzenesulfonic acid was 0.3 parts by mass.

[Example 23]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the amount of the cross-linking agent N was 4 parts by mass.

[Example 24]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the amount of the cross-linking agent N was 12 parts by mass.

[Example 25]
Adhesive in the same manner as in Example 1 except that 2 parts by mass of an acidic phosphate ester compound AP-4 (manufactured by Daihachi Chemical Industry Co., Ltd.) was used instead of the organic acid, and 12 parts by mass of the cross-linking agent N. manufactured.

[Example 26]
A pressure-sensitive adhesive in the same manner as in Example 1 except that 2 parts by mass of an acidic phosphate ester compound AP-10 (manufactured by Daihachi Chemical Industry Co., Ltd.) was used instead of the organic acid, and the cross-linking agent N was 12 parts by mass. manufactured.

[Example 27]
In the same manner as in Example 1, except that 2 parts by mass of the acidic phosphate ester compound Phosphanol ML-220 (manufactured by Toho Chemical Industry Co., Ltd.) was used instead of the organic acid, and 12 parts by mass of the cross-linking agent N was used. A pressure-sensitive adhesive was produced.

[Example 28]
In the same manner as in Example 1, except that 2 parts by mass of an acidic phosphate ester compound Phosphanol RS-710 (manufactured by Toho Chemical Industry Co., Ltd.) was used instead of the organic acid, and 12 parts by mass of the cross-linking agent N was used. A pressure-sensitive adhesive was produced.

[Example 29]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 1 part by mass of 2-ethylhexanoic acid was used as the organic acid.

[Example 30]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that 0.6 parts by mass of linear alkylbenzenesulfonic acid and 1 part by mass of 2-ethylhexanoic acid were used as organic acids.

[Comparative Example 1]
A pressure-sensitive adhesive was produced in the same manner as in Example 1, except that the organic acid and the acidic phosphate compound were not blended.

[Comparative Example 2]
A pressure-sensitive adhesive was produced in the same manner as in Comparative Example 1, except that 1 part by mass of a carboxylic acid ester represented by the chemical formula (1010) (where n is 10 on average) was added.

[Comparative Example 3]
A pressure-sensitive adhesive was produced in the same manner as in Comparative Example 1, except that 30 parts by mass of a carboxylic acid ester represented by the chemical formula (1010) (where n is 10 on average) was added.

The pressure-sensitive adhesives of Examples and Comparative Examples produced as described above were evaluated for adhesive strength (peel strength), wettability, and adherend contamination resistance by the following methods. The results are summarized in Table 2 below.

1. Adhesive strength Adhesive strength was evaluated using, as a sample, a pressure-sensitive adhesive sheet produced by coating a coating solution (adhesive) on a PET film having a thickness of 50 μm. In an environment of 23° C. and humidity of 50% RH, the sample was cut into a width of 25 mm and attached to an adherend (glass plate) under a load of 3 reciprocations of a 2 kg roller. After curing this for 1 hour, one end of the sample was peeled off at a speed of 300 mm/min in a 180° direction using an autograph, and the peel strength (N/25 mm) was taken as the adhesive strength. From the viewpoint of re-peelability, the peel strength of the pressure-sensitive adhesive sheet is preferably not excessively large, and is preferably 0.1 N/25 mm or less.

2. Wettability For the evaluation of wettability , a pressure-sensitive adhesive sheet produced by coating a PET film with a thickness of 50 μm with a coating liquid was used as a sample. The sample was cut into a size of 5 cm×10 cm, and only one side of the sample with a width of 5 cm was brought into contact with a glass plate while being tilted at 45°. Thereafter, the hand was released, and the time (seconds) required for the entire surface of the sample to come into contact with the glass plate (wet the glass plate) was evaluated as wettability. The shorter the time (seconds), the higher the wettability (adhesion) to the glass plate. The higher the wettability, the faster it can be attached to the adherend (the glass plate in this example). The wettability is preferably 10 seconds/10 cm or less.

3. Resistance to staining of adherend For evaluation of resistance to staining of adherend, a pressure-sensitive adhesive sheet produced by coating a PET film having a thickness of 50 µm with a coating liquid was used as a sample. The sample was cut into a size of 4 cm×10 cm, and an adhesive sheet was attached to a glass plate or PET film. After standing in a thermo-hygrostat of 80° C. and humidity of 80% RH for 72 hours, it was further left in an environment of 23° C. and humidity of 50% RH for 1 hour. Next, the pressure-sensitive adhesive sheet was peeled off from the glass plate or PET film, and the state of white contamination on the glass surface where the pressure-sensitive adhesive sheet was adhered was visually evaluated. The state of white contamination was evaluated by irradiating white light in a dark room.

(Evaluation result of adherend contamination resistance)
A: No white contaminants were observed on the glass surface.
◯: Spot-like white contaminants were found on part of the glass surface.
Δ: Mottled white contaminants were observed on the glass surface.
x: White contaminants were observed on the entire surface of the glass.

As shown in Tables 3 and 4, the pressure-sensitive adhesives of Examples 1 to 30 containing all components (A) to (C) had all of the adhesive strength (removability), wettability, and adherend contamination resistance. was good. That is, the pressure-sensitive adhesives of Examples 1 to 30 were able to simultaneously satisfy all of removability, wettability, and adherend stain resistance. On the other hand, the pressure-sensitive adhesives of Comparative Examples 1 to 3, which did not contain the component (B) (acid component), had good adhesive strength (removability) and wettability, but had poor adherend contamination resistance. It was inferior compared with the example.

As described above, according to the present invention, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a method for producing a pressure-sensitive adhesive sheet that can satisfy removability, wettability, and resistance to adherend contamination under high temperature and high humidity conditions, and an image display device. The pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and method for producing the pressure-sensitive adhesive sheet of the present invention can be used, for example, as protective sheets for window glass of mobile phones, smart phones, automobiles, buildings, and the like. In addition, the present invention is not limited to this, and can be widely used in various applications. For example, it is widely applicable to fields where general adhesives, adhesive sheets, and methods for producing adhesive sheets are used. .

This application claims priority based on Japanese Patent Application No. 2017-095993 filed on May 12, 2017, and the entire disclosure thereof is incorporated herein.

Claims (8)

a polyurethane prepolymer (A);
at least one selected from the group consisting of an organic acid (B-1), an acidic phosphate compound (B-2), and an organic acid anhydride (B-3) ;
and a cross-linking agent (C) that is a polyisocyanate ,
The acidic phosphate compound (B-2) is at least one selected from the group consisting of acidic phosphate compounds represented by the following chemical formulas (I), (II), and (III),
The organic acid (B-1) is an organic acid other than the acidic phosphate compound (B-2),
The polyurethane prepolymer (A) is
A pressure-sensitive adhesive that is a prepolymer having a plurality of hydroxyl groups synthesized from a polyol containing a trifunctional polyether polyol and an isocyanate.

In the chemical formula (I),
R ¹ and R ² are each a hydrogen atom, a hydrocarbon group or an aryl group;
R ¹ and R ² may be the same or different,
At least one of R ¹ and R ² is a hydrocarbon group or an aryl group.

In the chemical formulas (II) and (III),
R ³ and R ⁴ are each a hydrogen atom, a hydrocarbon group or an aryl group,
R ³ and R ⁴ may be the same or different,
at least one of R ³ and R ⁴ is a hydrocarbon group or an aryl group;
AO is an alkylene oxide group, each AO may be the same or different,
n represents an integer of 1 or more, and each n may be the same or different. 2. The pressure-sensitive adhesive according to claim 1, wherein the content of the polyether polyol in the polyurethane prepolymer (A) is 20 to 100 mol % in the polyol constituting the polyurethane polyol (polyurethane prepolymer (A)). 3. The adhesive according to claim 1, wherein the organic acid (B-1) is at least one of carboxylic acid and sulfonic acid. The adhesive according to any one of claims 1 to 3, wherein the organic acid anhydride (B-3) is at least one of a carboxylic acid anhydride and a sulfonic acid anhydride. The content of the organic acid (B-1), acidic phosphate compound (B-2), and organic acid anhydride (B-3) is 0.3 to 6% by mass relative to the total mass of the adhesive. The pressure-sensitive adhesive according to any one of claims 1 to 4. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on at least one surface of a substrate, wherein the pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive according to any one of claims 1 to 5 . Adhesive sheet. A coating step of applying the adhesive according to any one of claims 1 to 5 to the adhesive layer forming surface on which the adhesive layer is formed of the base material, and after the coating step, the adhesive 7. The method for producing a pressure-sensitive adhesive sheet according to claim 6 , further comprising the step of heating the pressure-sensitive adhesive on the layer forming surface. An image display device having a protective sheet for an image display device attached to an image display surface, wherein the protective sheet is the pressure-sensitive adhesive sheet according to claim 6 .