WO2019198488A1

WO2019198488A1 - Pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and method for manufacturing hydroxyl-terminated urethane prepolymer

Info

Publication number: WO2019198488A1
Application number: PCT/JP2019/012730
Authority: WO
Inventors: 秀平齋藤; 嘉孝戸根
Original assignee: 東洋インキＳｃホールディングス株式会社; トーヨーケム株式会社
Priority date: 2018-04-12
Filing date: 2019-03-26
Publication date: 2019-10-17
Also published as: CN110494527A; CN110494527B; KR102587039B1; JP6519687B1; TWI803614B; TW201943824A; JP2019183037A; KR20200140795A

Abstract

The present invention provides a pressure-sensitive adhesive that has excellent pot life and excellent initial curability, and that is capable of forming a pressure-sensitive adhesive layer which has excellent wettability and adhesion to materials, and which has good removability even if left under a high-temperature/high-humidity environment. This pressure-sensitive adhesive includes: a hydroxyl-terminated urethane polymer (UPH), which is a product of reaction between one or more species of polyisocyanate (N) and multiple species of active hydrogen group-containing compounds (HX) that contain polyether polyol (HA) having a number average molecular weight of 1,650 or more per functional group and an active hydrogen group-containing compound (HB) having a number average molecular weight of 300 or less per functional group; and a polyfunctional isocyanate compound (I). The active hydrogen group-containing compound (HB) includes an active hydrogen group-containing compound that contains only a primary hydroxyl group as the active hydrogen group.

Description

Pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and method for producing hydroxyl-terminated urethane prepolymer

The present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a method for producing a hydroxyl group-terminated urethane prepolymer.

Conventionally, pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer formed on a base material sheet have been widely used as surface protective sheets for various members. Examples of the pressure sensitive adhesive include acrylic pressure sensitive adhesive, silicone pressure sensitive adhesive, and urethane pressure sensitive adhesive. Acrylic pressure-sensitive adhesives are excellent in adhesive strength, but because of their strong adhesive strength, re-peelability after being attached to an adherend is not good. In particular, after aging in a high-temperature and high-humidity environment, the re-peelability is further lowered due to an increase in adhesive force, and there is a tendency to cause adherend contamination in which the adhesive remains on the surface of the adherend after re-peeling. . Silicone pressure-sensitive adhesives are likely to cause contamination of the adherend, and the silicone resin having a relatively low molecular weight may volatilize and be adsorbed on the surface of equipment such as an electronic device, causing problems. On the other hand, the urethane-based pressure-sensitive adhesive has good adhesion to the adherend, is relatively excellent in removability, and hardly volatilizes.
In this specification, the “pressure-sensitive adhesive” is a pressure-sensitive adhesive having removability (removable pressure-sensitive adhesive), and the “pressure-sensitive adhesive sheet” is a pressure-sensitive adhesive sheet having re-peelability (removable pressure-sensitive adhesive sheet).

A flat panel display such as a liquid crystal display (LCD) and an organic electroluminescence display (OELD), and a touch panel display in which such a flat panel display and a touch panel are combined include a television (TV), a personal computer (PC), a mobile phone, and Widely used in electronic devices such as portable information terminals.
Urethane pressure-sensitive adhesive sheets are flat panel displays and touch panel displays, and substrates manufactured or used in these manufacturing processes (glass substrates, and ITO / glass substrates on which ITO (indium tin oxide) films are formed on glass substrates). Etc.) and a surface protective sheet for optical members and the like.

As a method for producing a urethane-based pressure-sensitive adhesive, a method using a hydroxyl group-terminated urethane prepolymer and a polyfunctional isocyanate compound, which are reaction products of an active hydrogen group-containing compound such as a polyol and a polyisocyanate, and a hydroxyl group-terminated urethane prepolymer are used. There is a method (one-shot method) in which a polyol and a polyfunctional isocyanate compound are reacted at once.

A general method for producing a pressure-sensitive adhesive sheet includes a coating process in which a pressure-sensitive adhesive is coated on a base sheet, and a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive by heating and drying the formed coating layer. It includes a heating step, a winding step in which the obtained pressure-sensitive adhesive sheet is wound around a core to form a pressure-sensitive adhesive sheet roll, and a curing step for curing the pressure-sensitive adhesive sheet roll.

Japanese Patent No. 5,501,489 JP 2016-138237 A JP 2016-204468 A

Urethane pressure-sensitive adhesive cures immediately after production, but if the initial curability is too high, the pot life is shortened, and the viscosity of the pressure-sensitive adhesive becomes too high before the pressure-sensitive adhesive is applied on the base sheet. There is a risk that uniform coating will not be possible. If the initial curing property of the urethane pressure-sensitive adhesive is too low, the coating layer or the adhesive layer is subjected to hot air when the coating layer is heated and dried, or mechanically applied during winding and curing of the pressure-sensitive adhesive sheet obtained after heating and drying. Under the influence of stress, there is a possibility that surface appearance defects such as a winding core step mark, yuzu skin, and curl will occur in the adhesive layer. The urethane-based pressure-sensitive adhesive preferably has good initial curability while having a good pot life.

The adhesive sheet preferably has good adhesion (also referred to as substrate adhesion) of the adhesive layer to the substrate sheet. The pressure-sensitive adhesive sheet preferably has good removability so that it can be easily removed from the adherend when it is removed from the adherend while having good substrate adhesion. Even when the pressure-sensitive adhesive sheet is exposed to a high-temperature and high-humidity environment, it is preferable that the pressure-sensitive adhesive component is not contaminated on the surface of the adherend after re-peeling.

The pressure-sensitive adhesive layer preferably has good wettability with respect to an adherend such as glass, and it is preferable that air bubbles are not involved in the sticking interface when the pressure-sensitive adhesive sheet is stuck to the adherend. In the urethane-based pressure-sensitive adhesive, a plasticizer may be added in order to improve wettability. However, when the amount of the plasticizer added is large, particularly when exposed to a high-temperature and high-humidity environment, there is a risk of adherend contamination, in which the pressure-sensitive adhesive component remains on the surface of the adherend after re-peeling the pressure-sensitive adhesive sheet. is there. Therefore, it is preferable that the addition amount of the plasticizer is small, and it is more preferable that there is no addition amount of the plasticizer. It is preferable that the urethane-based pressure-sensitive adhesive has good wettability even in a blended composition in which the amount of plasticizer added is small / preferably no plasticizer is added.

Patent documents 1 to 3 are cited as related documents of the present invention.
Patent Document 1 discloses a polyol (A1) having 3 number-average molecular weight (Mn) having 3 OH groups and 8000 to 20000, a polyol (A2) having 3 or more OH groups and having a number-average molecular weight (Mn) of 5000 or less, and A urethane-based pressure-sensitive adhesive containing a polyurethane-based resin obtained by curing a composition containing a plurality of types of polyol (A) containing polyfunctional isocyanate compound (B) is disclosed (claim 1).

Patent Document 2 discloses a polyol composition for pressure-sensitive adhesives that contains the following polyol (A1) and is reacted with a polyisocyanate compound (B) to obtain a pressure-sensitive adhesive (Claim 1).
Polyol (A1): a polyoxy having a functional group number of 3 or more, a number average molecular weight (Mn) per functional group of 500 to 2500, and an oxyethylene group content of 16 mol% or more based on the total amount of oxyalkylene groups Alkylene polyols.
In Patent Document 2,
Having a main agent composition housed in a first container and a curing agent composition housed in a second container;
The main agent composition is the above polyol composition for pressure-sensitive adhesives,
The curing agent composition contains a polyisocyanate compound (B),
A pressure-sensitive adhesive kit in which one or both of the main agent composition and the curing agent composition contains a catalyst (C) is disclosed (Claim 5).

Patent Document 3 discloses that polyisocyanate C is obtained using polyether diol A having an unsaturation degree of 0.07 meq / g or less and a number average molecular weight (Mn) of 3000 to 30000 and polyisocyanate C. There is disclosed a urethane-based pressure-sensitive adhesive containing a urethane prepolymer in which the ratio of the NCO group of the diol group to the total amount of OH groups of the polyether diol A is in the range of 0.85 to 1.15 (molar ratio). Item 9).
Note that the reference numerals of the components described in Patent Documents 1 to 3 are those described in these references, and have nothing to do with the reference numerals used for the components of the present invention.

The urethane-based adhesives described in Patent Documents 1 and 2 are urethane-based adhesives by a one-shot method. Generally, an adhesive layer using a urethane-based adhesive obtained by a one-shot method is hard, and the surface smoothness of the adhesive layer tends to deteriorate due to curing shrinkage.
In the urethane-based pressure-sensitive adhesive described in Patent Document 3, polyether diol A having a number average molecular weight (Mn) per functional group of 1500 to 15000 is used as a raw material polyol for the urethane prepolymer. When such a relatively long-chain polyol is used as the raw material polyol for the urethane prepolymer, the wettability of the adhesive layer can be improved, but the initial curability of the adhesive is reduced, and the releasability of the adhesive layer is reduced. There is a tendency to decrease.

The present invention has been made in view of the above circumstances, and has good pot life and initial curability, and good wettability and substrate adhesion, even when placed in a high temperature and high humidity environment. It aims at providing the adhesive which can form the adhesive layer which has removability, and an adhesive sheet using the same.

The pressure-sensitive adhesive of the present invention is
Polyether polyol (HA) having a number average molecular weight of 1650 or more per functional group and an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule having a number average molecular weight of 300 or less per functional group A hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of a plurality of active hydrogen group-containing compounds (HX) containing (HB) and one or more polyisocyanates (N);
A polyfunctional isocyanate compound (I),
The active hydrogen group-containing compound (HB) includes an active hydrogen group-containing compound containing only a primary hydroxyl group as an active hydrogen group.

The pressure-sensitive adhesive sheet of the present invention includes a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention.

The method for producing a hydroxyl group-terminated urethane prepolymer of the present invention comprises one or more polyether polyols (HA) having a number average molecular weight (Mn) per functional group of 1650 or more, and one or more polyisocyanates (N), In an isocyanate group excess ratio to produce an isocyanate group-terminated urethane prepolymer (UPN);
The obtained isocyanate group-terminated urethane prepolymer (UPN) and one or more active hydrogen group-containing compounds having a plurality of active hydrogen groups in one molecule having a number average molecular weight (Mn) per functional group of 300 or less ( And a step of reacting with HB).

In this specification, “Mw” is a weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement. “Mn” is a polystyrene-equivalent number average molecular weight determined by GPC measurement. These can be measured by the method described in the [Example] section.

According to the present invention, an adhesive layer having good pot life and initial curability, good wettability and substrate adhesion, and good removability even when placed in a high temperature and high humidity environment. An adhesive that can be formed and an adhesive sheet using the same can be provided.

It is a schematic cross section of the adhesive sheet of 1st Embodiment which concerns on this invention. It is a schematic cross section of the adhesive sheet of 2nd Embodiment which concerns on this invention.

The pressure-sensitive adhesive of the present invention comprises a hydroxyl group-terminated urethane prepolymer (UPH), which is a reaction product of a plurality of types of active hydrogen group-containing compounds (HX) and one or more types of polyisocyanates (N), a polyfunctional isocyanate compound ( I) and a urethane-based pressure-sensitive adhesive.
In the present invention, the plural kinds of active hydrogen group-containing compounds (HX) include one or more polyether polyols (HA) having a number average molecular weight (Mn) per functional group of 1650 or more, and per functional group. And one or more active hydrogen group-containing compounds (HB) having a plurality of active hydrogen groups in one molecule having a number average molecular weight (Mn) of 300 or less.

The pressure-sensitive adhesive sheet of the present invention is a urethane-based pressure-sensitive adhesive sheet including a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the above-described pressure-sensitive adhesive of the present invention.

[Adhesive]
(Hydroxyl-terminated urethane prepolymer (UPH))
The hydroxyl group-terminated urethane prepolymer (UPH) is a reaction product obtained by copolymerizing a plurality of types of active hydrogen group-containing compounds (HX) and one or more types of polyisocyanate (N). The copolymerization reaction can be performed in the presence of one or more kinds of catalysts as necessary. In the copolymerization reaction, one or more solvents can be used as necessary.
The hydroxyl-terminated urethane prepolymer (UPH) is preferably an isocyanate group-terminated urethane prepolymer (UPN) which is a reaction product of a polyether polyol (HA) and a polyisocyanate (N), and an active hydrogen group-containing compound (HB). It is a reaction product.
In the present invention, the plural types of active hydrogen group-containing compounds (HX) include a relatively long-chain polyether polyol (HA) and a relatively short-chain active hydrogen group-containing compound (HB).

<Polyether polyol (HA)>
Polyether polyol (HA) has a number average molecular weight (Mn) per functional group of 1650 or more, and is more per active group than an active hydrogen group-containing compound generally used as a raw material for urethane (pre) polymer. It is a relatively long-chain polyether polyol having a large number average molecular weight (Mn).
As polyether polyol (HA), a well-known thing can be used. Polyether polyol (HA) is a compound (addition polymer) obtained by addition polymerization of one or more oxirane compounds using an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule as an initiator. Is mentioned.

Examples of the initiator include a hydroxyl group-containing compound and amines. Specifically, ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, xylylenediamine, etc. Functional initiators; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamine; and pentafunctional initiators such as diethylenetriamine.
Examples of the oxirane compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); tetrahydrofuran (THF) and the like.

The polyether polyol (HA) is preferably an alkylene oxide adduct of an active hydrogen-containing compound (also referred to as “polyoxyalkylene polyol”). Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), PPG (PPG-EO) having ethylene oxide (EO) added to the terminal, and polyalkylene glycol such as polytetramethylene glycol; Trifunctional polyether polyols such as alkylene oxide adducts of glycerin are preferred.

It is preferable that the degree of unsaturation of the polyether polyol (HA) is low. The degree of unsaturation is the total amount of unsaturated groups contained in 1 g of polyether polyol, and corresponds to the amount of impurity monool. By using a high-purity material with a low degree of unsaturation, the initial curability of the pressure-sensitive adhesive is improved, and it adheres to the surface of the adherend after re-peeling of the pressure-sensitive adhesive sheet, especially when exposed to high temperature and high humidity. The adherend contamination with the agent component remaining can be suppressed. The degree of unsaturation of the polyether polyol (HA) is preferably 0.07 meq / g or less, more preferably 0.04 meq / g or less, particularly preferably 0.01 meq / g or less.
In the present specification, unless otherwise specified, the degree of unsaturation of a polyol is a value measured according to JIS K1557 6.7.

<Active hydrogen group-containing compound (HB)>
The active hydrogen group-containing compound (HB) has a number average molecular weight (Mn) of 300 or less per functional group, and is one functional group than the active hydrogen group-containing compound generally used as a raw material for urethane (pre) polymer. It is a relatively short-chain active hydrogen group-containing compound having a small number average molecular weight (Mn) per unit.
Examples of the active hydrogen group include a hydroxy group, a mercapto group, and an amino group (in this specification, unless otherwise specified, an amino group includes an imino group). The active hydrogen group-containing compound (HB) is a polyol having a plurality of hydroxy groups in one molecule, a polyamine having a plurality of amino groups in one molecule, an amino alcohol having an amino group and a hydroxyl group in one molecule, one molecule Examples thereof include polythiol having a plurality of mercapto groups. These can be used alone or in combination of two or more. The active hydrogen group-containing compound (HB) may be a non-polymer or a polymer.
Of these, polyol is preferable. Since polyamines and polythiols are highly reactive and have a short pot life, when they are used, it is preferable to use them together with polyols. In addition, when the polyol contains a secondary hydroxyl group, the initial curability of the urethane-based pressure-sensitive adhesive is not improved. Therefore, from the viewpoint of pot life and initial curability, the active hydrogen group-containing compound (HB) has moderate reactivity 1 It preferably contains a secondary hydroxyl group.

Non-polymeric polyols include ethylene glycol (EG), propylene glycol (PG), diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol. 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6 -Hexanediol, 2-ethyl-1,3-hexanediol (also referred to as “1,3-octanediol”), 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octane Diol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane ( MP), pentaerythritol, and hexane triol, and the like.

Examples of the polymer polyol that can be used as the active hydrogen group-containing compound (HB) include polyester polyol, polyether polyol, polyacryl polyol, polycaprolactone polyol, polycarbonate polyol, and castor oil-based polyol. Of these, polyester polyols, polyether polyols, and combinations thereof are preferable.

As the polyester polyol that can be used as the active hydrogen group-containing compound (HB), known polyester polyols can be used. Examples of the polyester polyol include a compound (esterified product) obtained by an esterification reaction of at least one polyol component and at least one acid component.

Examples of the raw material polyol component include ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3- Hexanediol (1,3-octanediol), 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylol Examples include propane, pentaerythritol, hexanetriol, and the like.

The raw acid components include succinic acid, methyl succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, and acid anhydrides thereof Etc.

Known polyether polyols can be used as the polyether polyol that can be used as the active hydrogen group-containing compound (HB). Examples of the polyether polyol include compounds (addition polymerization products) obtained by addition polymerization of one or more oxirane compounds using an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule as an initiator. . As the initiator and the oxirane compound, the same compounds as those exemplified for the polyether polyol (HA) can be used.
As with the polyether polyol (HA), the polyether polyol that can be used as the active hydrogen group-containing compound (HB) is preferably an alkylene oxide adduct (polyoxyalkylene polyol) of the active hydrogen group-containing compound. Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), PPG (PPG-EO) having ethylene oxide (EO) added to the terminal, and polyalkylene glycol such as polytetramethylene glycol; Trifunctional polyether polyols such as alkylene oxide adducts of glycerin are preferred.

Polyamines that can be used as the active hydrogen group-containing compound (HB) include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6 -Hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecane Diamine, hexamethylenediamine, trimethylhexamethylenediamine, iminobispropylamine, methyliminobispropylamine, 1,5-diamino-2-methylpentane, isophoronediamine, 1,3-bisaminomethylcyclohexane, 1-cyclohexylamino- 3-aminop Pan, 3-aminomethyl-3,3,5-trimethyl-cyclohexylamine, norbornane skeleton dimethyleneamine, metaxylylenediamine (MXDA), hexamethylenediamine carbamate, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and Aliphatic polyamines such as pentaethylenehexamine; 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane 3,4'-diaminodiphenylmethane, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-pheny Diamine, p-phenylenediamine, 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, and diethyltoluene Aromatic polyamines such as diamines; and the like.

Examples of amino alcohols that can be used as the active hydrogen group-containing compound (HB) include monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane, and 2-amino-2. A monoamine having a hydroxyl group such as ethyl-1,3-propanediol; a diamine having a hydroxyl group such as N- (2-hydroxypropyl) ethanolamine; and the like.

Examples of polythiols that can be used as the active hydrogen group-containing compound (HB) include methanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 1, 3-benzenedithiol, 1,4-benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, 1,5 -Pentanedithiol, 1,2-propanedithiol, 1,3-propadithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1,2- Benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedi Tanthiol, 4,4′-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiadiazole, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, Examples include 2-di-n-butylamino-4,6-dimercapto-s-triazine, thiol group-terminated polymers (polysulfide polymers and the like), and the like.

Generally, in a urethane type adhesive, a plasticizer may be added in order to improve wettability. However, when the amount of the plasticizer added is large, particularly when exposed to a high-temperature and high-humidity environment, there is a risk of adherend contamination, in which the pressure-sensitive adhesive component remains on the surface of the adherend after re-peeling the pressure-sensitive adhesive sheet. is there.
In the present invention, as a raw material active hydrogen group-containing compound of a hydroxyl group-terminated urethane prepolymer (UPH), a relatively long-chain polyether polyol (HA) having a number average molecular weight (Mn) per functional group of 1650 or more, preferably Uses a relatively long-chain polyether polyol (HA) containing an alkyleneoxy (AO) group, so that the addition amount of the plasticizer is small / preferably with respect to the adherend even in a compounding composition without the addition amount of the plasticizer. An adhesive layer with good wettability can be formed. For example, when an adhesive sheet is attached to an adherend such as a glass substrate and an ITO / glass substrate, an adhesive layer in which bubbles are not easily involved in the attachment interface can be formed. A relatively large number of organic groups, preferably alkylene groups, that form an ether bond and bonded to an oxygen atom is considered to produce the same effect as a plasticizer.

When a relatively long-chain polyether polyol (HA) is used as a raw material for the hydroxyl-terminated urethane prepolymer (UPH), the wettability of the pressure-sensitive adhesive layer is improved, while the initial curability of the pressure-sensitive adhesive is reduced, Re-peelability tends to decrease. This tendency increases as the number average molecular weight (Mn) per functional group of the polyether polyol (HA) increases.
From the viewpoint of improving the wettability of the adhesive layer, the number average molecular weight (Mn) per functional group of the polyether polyol (HA) is preferably 2000 or more, more preferably 3000 or more.
In the present invention, by using a relatively short-chain active hydrogen group-containing compound (HB) as a raw material for the hydroxyl group-terminated urethane prepolymer (UPH), adhesion by using a relatively long-chain polyether polyol (HA) is used. It is possible to improve a decrease in initial curability of the agent and a decrease in removability of the adhesive layer.
From the viewpoint of improving the wettability of the pressure-sensitive adhesive layer, the initial curability of the pressure-sensitive adhesive, and the removability of the pressure-sensitive adhesive layer, the number average molecular weight (Mn) per functional group of the polyether polyol (HA) is preferably 2000 to It is 10,000, more preferably 3000 to 9000.
Monofunctionality of the active hydrogen group-containing compound (HB) can be effectively improved by reducing the initial curability of the pressure-sensitive adhesive and the removability of the pressure-sensitive adhesive layer by using a relatively long-chain polyether polyol (HA). The number average molecular weight (Mn) per group is preferably 30 to 300, more preferably 30 to 100.

The one or more polyether polyols (HA) may include a bifunctional polyether polyol and / or a trifunctional or higher polyether polyol. Similarly, the one or more active hydrogen group-containing compound (HB) may include a bifunctional active hydrogen group-containing compound and / or a trifunctional or higher functional hydrogen group-containing compound.
In general, a bifunctional active hydrogen group-containing compound has a two-dimensional crosslinkability, and can impart appropriate flexibility to the adhesive layer. A trifunctional or higher functional hydrogen group-containing compound has a three-dimensional crosslinkability and can impart an appropriate hardness to the adhesive layer.
By selecting the number of functional groups (number of active hydrogen groups) of one or more polyether polyols (HA) and one or more active hydrogen group-containing compounds (HB), the adhesive strength, cohesive strength of the urethane-based adhesive, And properties such as removability can be adjusted. Depending on the application, the number of functional groups of each material can be selected so that the properties such as adhesive strength, cohesive strength, and removability are within a preferable range. Since it is easy to make adhesive force and removability compatible, it is preferable that one or more polyether polyols (HA) include a tri- or more functional polyether polyol. One or more active hydrogen group-containing compounds (HB) preferably include a bifunctional active hydrogen group-containing compound because the reaction stability and cohesive force are easily achieved.

A plurality of active hydrogen group-containing compounds (HX), which are raw materials for the hydroxyl-terminated urethane prepolymer (UPH), contain known active hydrogen groups other than the polyether polyol (HA) and the active hydrogen group-containing compound (HB). One or more compounds may be included.

As related documents of the present invention, there are Patent Documents 1 to 3 listed in the “Background Art” section. These documents describe relatively long-chain polyols having a number average molecular weight (Mn) per functional group of 1650 or more, but the number average molecular weight (Mn) per functional group is 300 or less. There is no description or suggestion about the combined use of a relatively short chain active hydrogen group-containing compound (HB). Moreover, the urethane type adhesives of patent document 1, 2 are based on the one shot method, and do not use the hydroxyl-terminated urethane prepolymer.

<Polyisocyanate (N)>
As the polyisocyanate (N), known ones can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. Range isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4 ', 4 ”-Triphenylmethane triisocyanate, ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene , 1,4-tetramethyl xylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate and the like.

Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate. And 2,4,4-trimethylhexamethylene diisocyanate and the like.

The alicyclic polyisocyanates include isophorone diisocyanate (IPDI), 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 and the like.

Other examples of the polyisocyanate include trimethylolpropane adduct, biuret, allophanate, and trimer of the above polyisocyanate (this trimer includes an isocyanurate ring).

As the polyisocyanate (N), 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and the like are preferable. Although mentioned later for details, it is preferable that 1 or more types of polyisocyanate (N) contains isophorone diisocyanate (IPDI).

The preferable raw material compounding ratio of the hydroxyl group-terminated urethane prepolymer (UPH) is as follows.
The ratio (NCO / H) of the number of moles of isocyanate groups (NCO) of the polyisocyanate (N) to the total number of moles of active hydrogen groups (H) of the plural kinds of active hydrogen group-containing compounds (HX) is 0.20. It is preferable to determine the raw material blending ratio so as to be ˜0.84, more preferably 0.40 to 0.80. The closer NCO / H is to 1, the easier it is to gel when synthesizing a hydroxyl-terminated urethane prepolymer (UPH). If NCO / H is 0.84 or less, gelation during the synthesis of a hydroxyl-terminated urethane prepolymer (UPH) can be effectively suppressed.

Effect of improving the wettability of the pressure-sensitive adhesive layer by using polyether polyol (HA), effect of improving the initial curability and pressure-removability of the pressure-sensitive adhesive layer by using active hydrogen group-containing compound (HB), desired hydroxyl-terminated urethane From the viewpoint of stable synthesis of the prepolymer (UPH),
The amount of the one or more active hydrogen group-containing compounds (HB) is 0.5 to 40 parts by mass with respect to 100 parts by mass of one or more polyether polyols (HA), and one or more polyisocyanates (N ) Is preferably 1.0 to 20 parts by mass.
The amount of the one or more active hydrogen group-containing compounds (HB) is 1.0 to 20 parts by mass with respect to 100 parts by mass of one or more polyether polyols (HA), and one or more polyisocyanates (N ) Is more preferably 3.0 to 10 parts by mass.

<Catalyst>
In the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH), one or more kinds of catalysts can be used as necessary. Known catalysts can be used as the catalyst, and examples thereof include tertiary amine compounds and organometallic compounds.
Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU).
Examples of organometallic compounds include tin compounds and non-tin compounds.
Examples of tin compounds 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, and tin 2-ethylhexanoate.
Non-tin compounds include titanium-based compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride; lead-based compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; 2 -Iron systems such as iron ethylhexanoate and iron acetylacetonate; cobalt systems such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc systems such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate, etc. Zirconium type is mentioned.
The type and amount of the catalyst can be appropriately designed as long as the reaction proceeds well.

Due to the difference in reactivity of the plural types of active hydrogen group-containing compounds (HX), there is a possibility that gelation or reaction solution white turbidity easily occurs in a single catalyst system. In this case, by using two types of catalysts, it is easy to control the reaction (for example, reaction rate and the like), and the above problem can be solved. A combination of two kinds of catalysts is not particularly limited, and examples thereof include tertiary amine / organometallic, tin / non-tin, and tin / tin. Preferred are tin / tin, more preferably dibutyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate / dibutyltin dilaurate) is not particularly limited and is preferably more than 0 and less than 1, more preferably 0.2 to 0.6. is there. If the mass ratio is less than 1, the catalyst activity is well balanced, gelling and clouding of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

<Solvent>
In the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH), one or more solvents can be used as necessary. A well-known thing can be used as a solvent, Methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned. From the viewpoints of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent, ethyl acetate and toluene are particularly preferred.

<Polymerization method of hydroxyl-terminated urethane prepolymer (UPH)>
The polymerization method of the hydroxyl group-terminated urethane prepolymer (UPH) is not particularly limited, and known polymerization methods such as a bulk polymerization method and a solution polymerization method can be applied.
As a polymerization procedure of a hydroxyl-terminated urethane prepolymer (UPH),
Procedure 1) One or more polyether polyols (HA), one or more active hydrogen group-containing compounds (HB), one or more polyisocyanates (N), optionally one or more catalysts, and optionally Depending on the procedure, one or more solvents are batched into the flask;
Procedure 2) One or more polyether polyols (HA), one or more active hydrogen group-containing compounds (HB), optionally one or more catalysts, and optionally one or more solvents in the flask Charging and adding one or more polyisocyanates (N) dropwise thereto;
Procedure 3) One or more polyether polyols (HA), one or more polyisocyanates (N), one or more catalysts as required, and one or more solvents as needed in a batch. One or more active hydrogen group-containing compounds are prepared and reacted with a polyisocyanate (N) in an excess ratio of isocyanate groups to the polyether polyol (HA) to form an isocyanate group-terminated urethane prepolymer (UPN). The procedure of adding (HB);

When the catalyst is used, the reaction temperature is preferably less than 100 ° C, more preferably 50 to 95 ° C, and particularly preferably 60 to 85 ° C. When the reaction temperature is 100 ° C. or higher, it is difficult to control the reaction rate and polymerization stability, and it may be difficult to produce a hydroxyl group-terminated urethane prepolymer (UPH) having a desired molecular weight. The reaction temperature when no catalyst is used is preferably 100 ° C. or higher, more preferably 110 ° C. or higher.

In Procedure 1) and Procedure 2), a relatively long-chain polyether polyol (HA) and a relatively short-chain active hydrogen group-containing compound (HB) are simultaneously mixed with the polyisocyanate (N). In this method, a relatively short-chain active hydrogen group-containing compound (HB) having a high reactivity is preferentially combined with a polyisocyanate (N) over a relatively long-chain polyether polyol (HA) having a low reactivity. There is a tendency to react. In this case, a relatively long-chain polyether polyol (HA) having low reactivity may remain unreacted and the reaction solution may become cloudy. In order to eliminate the relatively long-chain polyether polyol (HA) remaining unreacted, when the number of moles of isocyanate groups is excessive with respect to the total number of moles of active hydrogen groups, An isocyanate group-terminated urethane prepolymer produced by the reaction of the active hydrogen group-containing compound (HB) with the polyisocyanate (N), a highly reactive relatively short-chain active hydrogen group-containing compound (HB), and Undesirable reactions may occur and the reaction solution may gel.

Procedure 3) is preferred because the reaction is easy to control. In the polymerization by this procedure, one or more polyether polyols (HA) and one or more polyisocyanates (N) are reacted in an excess ratio of isocyanate groups to produce isocyanate group-terminated urethane prepolymers (UPN). And a step of reacting the obtained isocyanate group-terminated urethane prepolymer (UPN) with one or more active hydrogen group-containing compounds (HB).

In step 3), only a relatively long-chain polyether polyol (HA) having a low reactivity is present in the absence of a relatively short-chain active hydrogen group-containing compound (HB). After the reaction, the resulting isocyanate group-terminated urethane prepolymer (UPN) is reacted with the active hydrogen group-containing compound (HB). In this method, gelation and white turbidity of the reaction solution can be suppressed, and a desired hydroxyl-terminated urethane prepolymer (UPH) can be stably synthesized.
Therefore, the hydroxyl group-terminated urethane prepolymer (UPH) includes an isocyanate group-terminated urethane prepolymer (UPN) which is a reaction product of a polyether polyol (HA) and a polyisocyanate (N), and an active hydrogen group-containing compound (HB). It is preferable that it is a reaction product with.
In procedure 3), it is preferred that the one or more polyisocyanate (N) comprises isophorone diisocyanate (IPDI). In this case, the reaction is easy to control, and a desired hydroxyl-terminated urethane prepolymer (UPH) can be stably synthesized.

(Polyfunctional isocyanate compound (I))
As the polyfunctional isocyanate compound (I), known compounds can be used, and compounds exemplified as polyisocyanate (N) which is a raw material of the hydroxyl-terminated urethane prepolymer (UPH) (specifically, aromatic polyisocyanate, aliphatic Polyisocyanate, araliphatic polyisocyanate, alicyclic polyisocyanate, and trimethylolpropane adduct / biuret / allophanate / trimer) can be used.

(Plasticizer (P))
As described above, the present invention can provide a pressure-sensitive adhesive having good wettability even with a blending composition in which the amount of plasticizer (P) added is small / preferably no plasticizer (P) is added. Therefore, in the pressure-sensitive adhesive of the present invention, the plasticizer (P) is not an essential component in order to improve wettability, but the pressure-sensitive adhesive of the present invention contains one or more plasticizers (P) as necessary. Can do. However, even when the plasticizer (P) is added, the amount can be suppressed to a low level. The amount of the plasticizer (P) relative to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH) may be, for example, 50 parts by mass or less (0-50 parts by mass), preferably 40 parts by mass or less (0-40 parts by mass), More preferably 30 parts by mass or less (0 to 30 parts by mass), further preferably 20 parts by mass or less (0 to 20 parts by mass), particularly preferably 10 parts by mass or less (0 to 10 parts by mass), and most preferably 5 parts by mass. Part or less (0 to 5 parts by mass).

The plasticizer (P) is not particularly limited, and an organic acid ester having a molecular weight of 250 to 1,000 is preferable from the viewpoint of compatibility with other components.

Examples of esters of monobasic acid or polybasic acid and alcohol include isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, phthalate Dibutyl acid, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diisodecyl adipate, diisostearyl adipate, dibutyl sebacate, diisocetyl sebacate, tributyl acetylcitrate, tributyl trimellitic acid, trimellit Examples include trioctyl acid, trihexyl trimellitic acid, trioleyl trimellitic acid, and triisocetyl trimellitic acid.

Examples of esters of other acids and alcohols include unsaturated fatty acids or branched acids such as myristoleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid, ethylene glycol, propylene glycol, and glycerin. , Esters with alcohols such as trimethylolpropane, pentaerythritol, and sorbitan.

Examples of esters of monobasic acid or polybasic acid and polyalkylene glycol include, for example, polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and dipolyethylene glycol methyl adipate Examples include ether.

From the viewpoint of improving wettability, the molecular weight (formula weight or Mn) of the organic acid ester is preferably 250 to 1,000, more preferably 400 to 900, and particularly preferably 500 to 850. When the molecular weight is 250 or more, the heat resistance of the pressure-sensitive adhesive layer is good, and when the molecular weight is 1,000 or less, the wettability of the pressure-sensitive adhesive is good.

(solvent)
The pressure-sensitive adhesive of the present invention can contain one or more solvents as required. A well-known thing can be used as a solvent, Methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned. From the viewpoint of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent, ethyl acetate and toluene are particularly preferable.

(Anti-alteration agent)
The pressure-sensitive adhesive of the present invention can contain one or more kinds of alteration preventing agents as required. Thereby, the fall of the various characteristics by long-term use of the adhesion layer can be suppressed. Examples of the alteration preventing agent include hydrolysis resistance, antioxidant, ultraviolet absorber, and light stabilizer.

<Hydrolysis-resistant agent>
When a hydrolysis reaction occurs in the adhesive layer in a high temperature and high humidity environment and a carboxy group is generated, a hydrolysis-resistant agent can be used to block the carboxy group. Examples of the hydrolysis-resistant agent include carbodiimide, isocyanate, oxazoline, and epoxy. Among these, a carbodiimide type is preferable from the viewpoint of the hydrolysis inhibiting effect.

A carbodiimide-based hydrolysis inhibitor is a compound having one or more carbodiimide groups in one molecule.
Examples of the monocarbodiimide compound include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, and naphthylcarbodiimide.
The polycarbodiimide compound can be produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst. Here, as the diisocyanate, for example, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4 '-Diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, Examples include 4,4′-dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate. The carbodiimidization catalysts include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl- Examples include 2-phospholene-1-oxide and phospholene oxides such as 3-phospholene isomers.

Examples of the isocyanate hydrolysis inhibitor include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-. Diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4, 4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene Isocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1, 4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'- Examples include dicyclohexylmethane diisocyanate and 3,3′-dimethyl-4,4′-dicyclohexylmethane diisocyanate.

Examples of the oxazoline-based hydrolysis inhibitor include 2,2′-o-phenylenebis (2-oxazoline), 2,2′-m-phenylenebis (2-oxazoline), and 2,2′-p-phenylenebis. (2-oxazoline), 2,2'-p-phenylenebis (4 -methyl-2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline), 2,2'-p -Phenylenebis (4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4,4'-dimethyl-2-oxazoline), 2,2'-ethylenebis (2-oxazoline) 2,2′-tetramethylenebis (2-oxazoline), 2,2′-hexamethylenebis (2-oxazoline), 2,2′-octamethylenebis (2-oxazoline), 2,2 ′ Ethylenebis (4-methyl-2-oxazoline), and 2,2'-diphenylenebis (2-oxazoline).

Examples of the epoxy hydrolyzing agent include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, And polyglycidyl ethers of aliphatic polyols such as trimethylolpropane; polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol; terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, and sebacic acid Diglycidyl or polyglycidyl esters of aliphatic or aromatic polycarboxylic acids; resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p- Diglycidyl or polyglycidyl ethers of polyhydric phenols such as droxyphenyl) propane, tris- (p-hydroxyphenyl) methane, and 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane; N, N N-glycidyl derivatives of amines such as diglycidylaniline, N, N-diglycidyltoluidine, and N, N, N ′, N′-tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl of aminophenol Derivatives; triglycidyl tris (2-hydroxyethyl) isocyanurate and triglycidyl isocyanurate; epoxy resins such as orthocresol type epoxy resin and phenol novolac type epoxy resin.

The addition amount of the hydrolysis-resistant agent is not particularly limited, and is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4.5 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). Particularly preferred is 0.5 to 3 parts by mass.

<Antioxidant>
Examples of the antioxidant include a radical scavenger and a peroxide decomposer. Examples of the radical scavenger include phenolic compounds and amine compounds. Examples of the peroxide decomposing agent include sulfur compounds and phosphorus compounds.

Examples of phenolic compounds include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearin-β- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [Β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undeca Benzenepropanoic acid, 3,5-bis (1,1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester, 1,1,3-tris (2-methyl-4-hydroxy-5) -T-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis- (4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester 1,3,5-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, and tocopherol And the like.

Examples of sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate.

Examples of phosphorus compounds include triphenyl phosphite, diphenylisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenylditridecyl) phosphite, and cyclic neopentanetetrayl. Bis (octadecylphosphite), tris (nonylphenyl) phosphite, tris (monononylphenyl) phosphite, tris (dinonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10 -Decyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) ) Phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, and 2,2-methylenebis (4,6-di-tert-butylphenyl) octylphos Fight etc. are mentioned.

By using an antioxidant, it is possible to prevent thermal degradation of the hydroxyl-terminated urethane prepolymer (UPH). Moreover, the bleeding out of the plasticizer (P) from the adhesion layer when using the plasticizer (P) can be effectively suppressed.
The addition amount of the antioxidant is not particularly limited, and is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, particularly preferably 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). Is 0.2 to 2 parts by mass.

As the antioxidant, from the viewpoint of stability and antioxidant effect, it is preferable to use one or more phenolic compounds that are radical scavengers, and one or more phenolic compounds that are radical scavengers and peroxide decomposers. It is more preferable to use one or more phosphorus compounds in combination. Further, it is particularly preferable to use a phenolic compound that is a radical scavenger and a phosphorus compound that is a peroxide decomposing agent in combination as an antioxidant, and to use these antioxidants in combination with the aforementioned hydrolysis-resistant agent. .

<Ultraviolet absorber>
Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, salicylic acid compounds, oxalic anilide compounds, cyanoacrylate compounds, and triazine compounds.
The addition amount of the ultraviolet absorber is not particularly limited, and is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). Particularly preferred is 0.2 to 2 parts by mass.

<Light stabilizer>
Examples of the light stabilizer include hindered amine compounds and hindered piperidine compounds. The addition amount of the light stabilizer is not particularly limited, and is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). The amount is particularly preferably 0.2 to 1 part by mass.

(Antistatic agent)
The pressure-sensitive adhesive of the present invention can contain one or more antistatic agents (AS agents) as necessary. Examples of the antistatic agent include inorganic salts, polyhydric alcohol compounds, ionic liquids, surfactants, and the like, and among these, ionic liquids are preferable. The “ionic liquid” is also called a room temperature molten salt, and is a salt that has fluidity at 25 ° C.

Examples of inorganic salts include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate , Sodium carbonate, sodium thiocyanate and the like.

Examples of the polyhydric alcohol compound include propanediol, butanediol, hexanediol, polyethylene glycol, trimethylolpropane, and pentaerythritol.

Examples of ionic liquids containing imidazolium ions include 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, and 1-butyl. -3-Methylimidazolium bis (trifluoromethylsulfonyl) imide and the like.

Examples of ionic liquids containing pyridinium ions include 1-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-butylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4- Methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide, 1-methylpyridinium bis (perfluoroethylsulfonyl) ) Imide, and 1-methyl-pyridinium bis (perfluorobutylsulfonyl) imide, and the like.

Examples of the ionic liquid containing ammonium ions include trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl- N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, and tri-n-butylmethylammonium bistrifluoromethanesulfone An imide etc. are mentioned.

In addition, commercially available ionic liquids such as pyrrolidinium salts, phosphonium salts, and sulfonium salts can be used as appropriate.

Surfactants are classified into low molecular surfactants and high molecular surfactants. In any type, there are nonionic, anionic, cationic and amphoteric types.

Nonionic low molecular surfactants include glycerin fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, and fatty acid diethanolamides. It is done.
Examples of the anionic low molecular surfactant include alkyl sulfonates, alkyl benzene sulfonates, and alkyl phosphates.
Examples of the cationic low molecular surfactant include tetraalkylammonium salts and trialkylbenzylammonium salts.
Examples of amphoteric low molecular surfactants include alkyl betaines and alkyl imidazolium betaines.

Examples of the nonionic polymer surfactant include polyether ester amide type, ethylene oxide-epichlorohydrin type, and polyether ester type.
Examples of the anionic polymer surfactant include polystyrene sulfonic acid type.
Examples of the cationic polymer surfactant include a quaternary ammonium base-containing acrylate polymer type.
Examples of amphoteric polymer surfactants include amino acid-type amphoteric surfactants such as higher alkylaminopropionates, betaine-type amphoteric surfactants such as higher alkyldimethylbetaine, and higher alkyldihydroxyethylbetaine.

The addition amount of the antistatic agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH).

(Leveling agent)
The pressure-sensitive adhesive of the present invention can contain a leveling agent as required. By adding a leveling agent, the leveling property of the adhesive layer can be improved. Examples of the leveling agent include an acrylic leveling agent, a fluorine leveling agent, a silicone leveling agent, and the like. From the viewpoint of suppressing adherend contamination after re-peeling the adhesive sheet, an acrylic leveling agent is preferable.

The weight average molecular weight (Mw) of the leveling agent is not particularly limited, and is preferably 500 to 20,000, more preferably 1,000 to 15,000, and particularly preferably 2,000 to 10,000. When Mw is 500 or more, the amount of vaporization from the coating layer is sufficiently small when the coating layer is heated and dried, and surrounding contamination is suppressed. If Mw is 20,000 or less, the improvement effect of the leveling property of an adhesion layer will express effectively.

The addition amount of the leveling agent is not particularly limited, and is preferably based on 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH) from the viewpoint of suppressing adherend contamination after the peeling of the adhesive sheet and improving the leveling property of the adhesive layer. The amount is 0.001 to 2 parts by mass, more preferably 0.01 to 1.5 parts by mass, and particularly preferably 0.1 to 1 part by mass.

(Other optional ingredients)
The pressure-sensitive adhesive of the present invention can contain other optional components as necessary, as long as the effects of the present invention are not impaired. Other optional components include catalysts, resins other than urethane resins, fillers (talc, calcium carbonate, titanium oxide, etc.), metal powders, colorants (pigments, etc.), foils, softeners, electrical conductivity Agents, silane coupling agents, lubricants, corrosion inhibitors, heat resistance stabilizers, weather resistance stabilizers, polymerization inhibitors, antifoaming agents, and the like.

(Mixing ratio)
The pressure-sensitive adhesive of the present invention contains one or more hydroxyl-terminated urethane prepolymers (UPH) and one or more polyfunctional isocyanate compounds (I) as essential components, and further contains one or more optional components as necessary. . These mixing ratios are not particularly limited, but preferable mixing ratios are as follows.
The amount of the one or more polyfunctional isocyanate compound (I) with respect to 100 parts by mass of the one or more hydroxyl-terminated urethane prepolymer (UPH) is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass. If the amount of the one or more polyfunctional isocyanate compound (I) is 3 parts by mass or more, the cohesive force of the adhesive layer is good, and if it is 20 parts by mass or less, the pot life is good.

(Method for producing adhesive)
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited.
One or more polyfunctional isocyanate compounds (I) and optionally one or more optional components are added to the hydroxyl group-terminated urethane prepolymer (UPH) synthesized by the above method (preferably Procedure 3)) By mixing, the pressure-sensitive adhesive of the present invention can be produced.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention. An adhesion layer can be formed in the single side | surface or both surfaces of a base material sheet. If necessary, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is peeled off when the pressure-sensitive adhesive sheet is attached to the adherend.

In FIG. 1, the schematic cross section of the adhesive sheet of 1st Embodiment which concerns on this invention is shown. In FIG. 1, reference numeral 10 is an adhesive sheet, reference numeral 11 is a base sheet, reference numeral 12 is an adhesive layer, and reference numeral 13 is a release sheet. The pressure-sensitive adhesive sheet 10 is a single-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed on one side of a base sheet.
In FIG. 2, the schematic cross section of the adhesive sheet of 2nd Embodiment which concerns on this invention is shown. In FIG. 2, reference numeral 20 is an adhesive sheet, reference numeral 21 is a base material sheet,

reference numerals

22A and 22B are adhesive layers, and

reference numerals

23A and 23B are release sheets.

The substrate sheet is not particularly limited, and examples thereof include a resin sheet, paper, and metal foil. The base sheet may be a laminated sheet in which any one or more layers are laminated on at least one surface of these base sheets. The surface of the base sheet on the side where the adhesive layer is to be formed may be subjected to easy adhesion treatment such as corona discharge treatment and anchor coating agent application, if necessary.

The constituent resin of the resin sheet is not particularly limited, and ester resins such as polyethylene terephthalate (PET); olefin resins such as polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride; nylon 66 and the like Amide resins; urethane resins (including foams); and combinations thereof.
The thickness of the resin sheet excluding the polyurethane sheet is not particularly limited and is preferably 15 to 300 μm. The thickness of the polyurethane sheet (including foam) is not particularly limited, and is preferably 20 to 50,000 μm.

The paper is not particularly limited, and examples thereof include plain paper, coated paper, and art paper.
The constituent metal of the metal foil is not particularly limited, and examples thereof include aluminum, copper, and combinations thereof.

The release sheet is not particularly limited, and a known release sheet in which a known release treatment such as application of a release agent is performed on the surface of a base sheet such as a resin sheet or paper can be used.

An adhesive sheet can be manufactured by a well-known method.
First, the pressure-sensitive adhesive of the present invention is applied to the surface of the base sheet to form a coating layer made of the pressure-sensitive adhesive of the present invention. A known method can be applied as the coating method, and examples thereof include a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.
Next, the coating layer is dried and cured to form an adhesive layer made of a cured product of the adhesive of the present invention. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C. The thickness of the adhesive layer (thickness after drying) varies depending on the use, but is preferably 0.1 to 200 μm.
Next, if necessary, a release sheet is attached to the exposed surface of the adhesive layer by a known method.
A single-sided adhesive sheet can be manufactured as described above.
A double-sided PSA sheet can be produced by performing the above operations on both sides.

Contrary to the above method, the pressure-sensitive adhesive of the present invention is applied to the surface of the release sheet to form a coating layer composed of the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to obtain the present invention. An adhesive layer made of a cured product of the adhesive may be formed, and a substrate sheet may be laminated on the exposed surface of the adhesive layer.

The production method of the pressure-sensitive adhesive sheet is preferably a coating step in which a pressure-sensitive adhesive is coated on the base sheet, and heating to form a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive by heating and drying the formed coating layer. A process, a winding process in which the obtained pressure-sensitive adhesive sheet is wound around a core to form a pressure-sensitive adhesive sheet roll, and a curing process for curing the pressure-sensitive adhesive sheet roll.

In the pressure-sensitive adhesive of the present invention, a relatively long-chain polyether polyol (HA) is used as the raw material active hydrogen group-containing compound of the hydroxyl group-terminated urethane prepolymer (UPH). An adhesive layer having good wettability can be formed even with a blending composition in which no plasticizer is added.

In the present invention, as a raw material active hydrogen group-containing compound of a hydroxyl group-terminated urethane prepolymer (UPH), a relatively short-chain polyether polyol (HA) is used in combination with a relatively short-chain active hydrogen group-containing compound (HB). ) Can reduce the initial curability of the pressure-sensitive adhesive and the re-peelability of the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive of the present invention can have good initial curability while having a good pot life. Since the pressure-sensitive adhesive of the present invention has a good pot life, the viscosity of the pressure-sensitive adhesive does not become too high before the pressure-sensitive adhesive is applied on the base sheet, and the pressure-sensitive adhesive can be applied uniformly. It is. Since the pressure-sensitive adhesive of the present invention has good initial curability, the coating layer or the pressure-sensitive adhesive layer is heated when the coating layer is heated and dried, or when the pressure-sensitive adhesive sheet obtained after heating and drying is wound and cured. It is difficult to be affected by the mechanical stress to be received, and it is possible to suppress the occurrence of surface appearance defects such as a winding core step mark, a yuzu skin, and a curl in the adhesive layer.
In the pressure-sensitive adhesive of the present invention, addition of a plasticizer can be reduced or eliminated, and a relatively short-chain active hydrogen group-containing compound as a raw material active hydrogen group-containing compound of a hydroxyl group-terminated urethane prepolymer (UPH) By using (HB), particularly when exposed to a high-temperature and high-humidity environment, it is possible to effectively suppress adherend contamination in which the pressure-sensitive adhesive component remains on the surface of the adherend after re-peeling of the pressure-sensitive adhesive sheet. it can.
The adhesive of the present invention also has good substrate adhesion.

As described above, according to the present invention, the pot life and the initial curability are good, and the wettability and the substrate adhesion are good, and the re-peeling is good even when placed in a high temperature and high humidity environment. A pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet using the same can be provided.

[Usage]
The pressure-sensitive adhesive sheet of the present invention can be used in the form of a tape, a label, a seal, a double-sided tape and the like. The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protective sheet, a cosmetic sheet, a non-slip sheet, and the like.
Flat panel displays such as liquid crystal displays (LCD) and organic electroluminescence displays (OELD), and touch panel displays in which such flat panel displays and touch panels are combined include televisions (TVs), personal computers (PCs), mobile phones, And widely used in electronic devices such as portable information terminals.
The pressure-sensitive adhesive sheet of the present invention includes a flat panel display and a touch panel display (collectively referred to simply as “display”), and a substrate manufactured or used in these manufacturing processes (a glass substrate and ITO on the glass substrate). (ITO / glass substrate or the like on which an (indium tin oxide) film is formed) and a surface protective sheet for optical members and the like.

Hereinafter, synthesis examples, examples according to the present invention, and comparative examples will be described. In the following description, unless otherwise specified, “part” means part by mass, “%” means mass%, and “RH” means relative humidity.

[Measurement of Mn and Mw]
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC) method. The measurement conditions were as follows. Mn and Mw are both polystyrene equivalent values.
<Measurement conditions>
Apparatus: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column; Two TSKgelGMH made by TOSOH are connected in series.
Detector: differential refractive index detector (RID-10A),
Solvent: tetrahydrofuran (THF),
Flow rate: 1 mL / min,
Solvent temperature: 40 ° C.
Sample concentration: 0.1%
Sample injection volume: 100 μL.

[material]
The materials used are as follows.
<Polyether polyol (HA) having a number average molecular weight (Mn) per functional group of 1650 or more>
(HA-1): Preminol 5001F (abbreviation in the table: PREM 5001F), manufactured by Asahi Glass Co., Ltd., bifunctional polyether polyol, Mn4000, hydroxyl number 2, hydroxyl value 28, unsaturation degree 0.02,
(HA-2): Preminol S4013F (abbreviation in the table: PREM S4013F), manufactured by Asahi Glass Co., Ltd., bifunctional polyether polyol, Mn 12000, hydroxyl number 2, hydroxyl value 9, unsaturation degree 0.007,
(HA-3): Preminol S4318F (abbreviation in the table: PREM S4318F), manufactured by Asahi Glass Co., Ltd., bifunctional polyether polyol, Mn 18000, hydroxyl number 2, hydroxyl value 6, unsaturation degree 0.007,
(HA-4): Exenol 828 (abbreviation in table: EXCE 828), manufactured by Asahi Glass Co., Ltd., trifunctional polyether polyol, Mn5000, hydroxyl number 3, hydroxyl value 34, unsaturation degree 0.07,
(HA-5): Preminol S3011 (abbreviation in the table: PREM S3011), manufactured by Asahi Glass Co., Ltd., trifunctional polyether polyol, Mn 10,000, hydroxyl number 3, hydroxyl value 17, unsaturation degree 0.006,
(HA-6): Preminol 3012 (abbreviation in table: PREM 3012), manufactured by Asahi Glass Co., Ltd., trifunctional polyether polyol, Mn 12000, hydroxyl number 3, hydroxyl value 14, unsaturation degree 0.020,
(HA-7): Exenol 838 (abbreviation in the table: EXCE 838), manufactured by Asahi Glass Co., Ltd., tetrafunctional polyether polyol, Mn 8000, hydroxyl number 4, hydroxyl value 28, unsaturation degree 0.07.
The unit of unsaturation is meq / g.
Table 1 shows the number of functional groups, Mn, Mn per functional group, and degree of unsaturation of each polyether polyol (HA).

<General-purpose polyether polyol (HM) having a number average molecular weight (Mn) per functional group of more than 300 and less than 1650>
(HM-1): PP-2000, manufactured by Sanyo Chemical Co., Ltd., bifunctional polyether polyol, Mn2000, hydroxyl number 2, hydroxyl value 56,
(HM-2): G-1500, manufactured by Adeka, trifunctional polyether polyol, Mn 1500, hydroxyl number 3, hydroxyl value 112,
(HM-3): G-3000B, manufactured by Adeka Corporation, trifunctional polyether polyol, Mn 3000, hydroxyl number 3, hydroxyl value 56.
Table 1 shows the number of functional groups, Mn, and Mn per functional group of each polyether polyol (HM).

<Active hydrogen group-containing compound (HB) having a number average molecular weight (Mn) per functional group of 300 or less>
(HB-1): ethylene glycol (EG) containing only primary hydroxyl groups,
(HB-2): 1,5-pentanediol, containing only primary hydroxyl groups,
(HB-3): 2-ethyl-1,3-hexanediol (1,3-octanediol), including a primary hydroxyl group and a secondary hydroxyl group,
(HB-4): PPG600 (the number indicates Mn, the same applies to PEG), polypropylene glycol, manufactured by Sanyo Kasei Co., Ltd., containing only secondary hydroxyl groups,
(HB-5): PEG300, polyethylene glycol, manufactured by Sanyo Chemical Co., Ltd., containing only primary hydroxyl groups,
(HB-6): PEG 600, polyethylene glycol, manufactured by Sanyo Chemical Co., Ltd., containing only primary hydroxyl groups,
(HB-7): including glycerin, primary hydroxyl group and secondary hydroxyl group,
(HB-8): Trimethylolpropane (TMP), containing only primary hydroxyl groups,
(HB-9): SP-750, manufactured by Sanyo Kasei Co., Ltd., hexafunctional polyether polyol, Mn700, containing 6 hydroxyl groups and only secondary hydroxyl groups,
(HB-10): Isophoronediamine.
Table 1 shows the number of functional groups, Mn, and Mn per functional group of each active hydrogen group-containing compound (HB).

<Polyisocyanate (N)>
(N-1): Isophorone diisocyanate (IPDI), manufactured by Tokyo Chemical Industry Co., Ltd.
(N-2): Hexamethylene diisocyanate (HDI), manufactured by Tokyo Chemical Industry Co., Ltd.
(N-3): Tolylene diisocyanate (a mixture of 2,4-tolylene diisocyanate (80% by mass) and 2,6-tolylene diisocyanate (20% by mass)) (TDI), manufactured by Tosoh Corporation.
Table 1 shows the number of functional groups, Mn, and Mn per functional group of each polyisocyanate (N).

<Polyfunctional isocyanate compound (I)>
(I-1) Coronate HL, manufactured by Tosoh Corporation, hexamethylene diisocyanate (HDI) / trimethylolpropane (TMP) adduct,
(I-2) Sumidur N-3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI) / isocyanurate,
(I-3) Sumidur N-75, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI) / isocyanabiuret,
(I-4) Desmodule Z4470BA, manufactured by Sumika Bayer Urethane Co., Ltd., isophorone diisocyanate (IPDI) / isocyanurate.

<Antioxidant (C)>
(C-1): IRGANOX 1135 (manufactured by BASF).
<Antistatic agent (AS agent) (E)>
(E-1): Elexel AS-804 (Daiichi Kogyo Seiyaku Co., Ltd.).
<Plasticizer (P)>
(P-1): ATBC (manufactured by Mitsubishi Chemical Corporation), tributyl acetylcitrate.

[Synthesis example of hydroxyl-terminated urethane prepolymer (UPH)]
(Synthesis Example 1) (Two-stage polymerization method)
In a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 100 parts by mass of polyether polyol (HA-1), 10 parts by mass of polyisocyanate (N-1), toluene 47 parts by mass and 0.01 part by mass of dioctyltin dilaurate as a catalyst were charged and mixed. The content liquid was gradually heated to 80 ° C. and reacted for 2 hours to obtain an isocyanate group-terminated urethane prepolymer (first stage reaction). Next, the content liquid was cooled to 60 ° C., 28 parts by mass of ethyl acetate was added, and then 4 parts by mass of an active hydrogen group-containing compound (HB-2) was added to cause a reaction (second stage reaction). In the entire reaction of the first stage and the second stage, all the active hydrogen group-containing compounds (HX) used in the reaction (in this example, (HA-1) and (HB-1)) have active hydrogen groups (H ) The ratio (NCO / H) of the number of moles of isocyanate groups (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles) was 0.71.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to terminate the reaction, and the hydroxyl-terminated urethane prepolymer (non-volatile content 60%, viscosity 2,100 cps, colorless transparent) A solution of UPA-1) was obtained. The obtained hydroxyl-terminated urethane prepolymer had Mn = 16,000 and Mw = 43,000.
The number of moles of isocyanate groups (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles of active hydrogen groups (H) of the compound composition, all active hydrogen group-containing compounds (HX) used in the reaction The ratio (NCO / H) and Mn and Mw of the obtained hydroxyl-terminated urethane prepolymer are shown in Table 2-1. The unit of the blending amount is “part by mass” (the same applies to other tables).

(Synthesis Examples 2 to 42) (Two-stage polymerization method)
In Synthesis Examples 2 to 42, the same procedure as in Synthesis Example 1 was conducted except that the types of polyether polyol (HA), active hydrogen group-containing compound (HB), and polyisocyanate (N) used and the blending ratio thereof were changed. Thus, colorless and transparent hydroxyl group-terminated urethane prepolymers (UPA-2) to (UPA-42) were obtained by a two-stage polymerization method.
In each synthesis example, the isocyanate group (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles of active hydrogen groups (H) of the active hydrogen group-containing compound (HX) used in the composition, the reaction ) Molar ratio (NCO / H) and Mn and Mw of the obtained hydroxyl-terminated urethane prepolymer are shown in Tables 2-1 to 2-5.

(Synthesis Example 43) (One-stage polymerization method)
In a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel, 100 parts by mass of polyether polyol (HA-6) and 4 parts by mass of active hydrogen group-containing compound (HB-2) Parts, 47 parts by mass of toluene, and 0.01 parts by mass of dioctyltin dilaurate as a catalyst were mixed and mixed, and the temperature was gradually raised to 80 ° C. To the content liquid, 9 parts by mass of polyisocyanate (N-1) and 28 parts by mass of ethyl acetate were added and reacted for 2 hours. Polyisocyanate used in the reaction with respect to the total number of moles of active hydrogen groups (H) possessed by all active hydrogen group-containing compounds (HX) used in the reaction (in this example, (HA-6) and (HB-2)) The ratio (NCO / H) of the number of moles of isocyanate groups (NCO) possessed by (N) was 0.58.
After confirming the disappearance of the remaining isocyanate groups by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to terminate the reaction, and a hydroxyl-terminated urethane prepolymer (non-volatile content 60%, viscosity 3,300 cps, white opaque) A solution of UPA-43) was obtained. The obtained hydroxyl-terminated urethane prepolymer had Mn = 26,000 and Mw = 73,000.
The number of moles of isocyanate groups (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles of active hydrogen groups (H) of the compound composition, all active hydrogen group-containing compounds (HX) used in the reaction The ratio (NCO / H) and Mn and Mw of the obtained hydroxyl-terminated urethane prepolymer are shown in Table 2-5.

(Synthesis Examples C1 to C6) (One-stage polymerization method)
In Synthesis Examples C1 to C6, types of active hydrogen group-containing compounds (HX) selected from polyether polyol (HA), polyether polyol (HM), and active hydrogen group-containing compound (HB), In the same manner as in Synthesis Example 43 except that the type of isocyanate (N) and the blending ratio thereof were changed, a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPB-1) to (UPB-1) to ( A solution of UPB-6) was obtained.
In each synthesis example, the isocyanate group (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles of active hydrogen groups (H) of the active hydrogen group-containing compound (HX) used in the composition, the reaction ) Molar ratio (NCO / H), and Mn and Mw of the obtained hydroxyl-terminated urethane prepolymer are shown in Table 2-6.

(Synthesis Example C7) (Two-stage polymerization method)
In Synthesis Example C7, polyether polyol (HM-3) was used instead of polyether polyol (HA-1), and the types and raw material blending ratios of active hydrogen group-containing compound (HB) and polyisocyanate (N) were changed. Except for the above, a colorless and transparent solution of a hydroxyl group-terminated urethane prepolymer (UPB-7) was obtained by a two-stage polymerization method in the same manner as in Synthesis Example 1.
The number of moles of isocyanate groups (NCO) of the polyisocyanate (N) used in the reaction with respect to the total number of moles of active hydrogen groups (H) of the compound composition, all active hydrogen group-containing compounds (HX) used in the reaction The ratio (NCO / H) and Mn and Mw of the obtained hydroxyl-terminated urethane prepolymer are shown in Table 2-6.

(Formulation example D1)
In Formulation Example D1, a polyether polyol (HA-6), an active hydrogen group-containing compound (HB-3), 47 parts by mass of toluene, 28 parts by mass of ethyl acetate, and 0.01 parts by mass of dioctyltin dilaurate as a catalyst are charged. By mixing, a colorless and transparent solution of polyol (PO-1) for comparison (polyol mixed solution) was obtained. The blending composition is shown in Table 2-6.

[Manufacture of urethane adhesives and adhesive sheets]
Example 1
100 parts by mass of a solution of the hydroxyl group-terminated urethane prepolymer (UPA-1) obtained in Synthesis Example 1, 10 parts by mass of a polyfunctional isocyanate compound (I-1), 1 part by mass of an antioxidant (C-1), and a solvent As a mixture, 100 parts by mass of ethyl acetate was mixed and stirred with a disper to obtain a urethane-based pressure-sensitive adhesive. In addition, the usage-amount of each material other than a solvent shows a non-volatile content conversion value (it is the same also in another Example and a comparative example). The composition is shown in Table 3-1. Pot life evaluation was implemented about the obtained adhesive.
A 50 μm thick polyethylene terephthalate (PET) film (Lumirror T-60, manufactured by Toray Industries, Inc.) was prepared as a base sheet. Using a comma coater (registered trademark), the obtained urethane pressure-sensitive adhesive was coated on one side of the base sheet so that the thickness after drying was 12 μm. Next, the formed coating layer was dried at 100 ° C. for 2 minutes to form an adhesive layer. On this adhesive layer, a 38 μm-thick release sheet (Super Stick SP-PET38, manufactured by Lintec Corporation) was attached to obtain an adhesive sheet. The initial curability was evaluated after curing for 3 hours under the condition of 23 ° C.-50% RH. Other evaluations were carried out after curing for 1 week under the condition of 23 ° C.-50% RH.

(Examples 2 to 55, Comparative Examples 1 to 8)
In each of Examples 2 to 55 and Comparative Examples 1 to 8, the same manner as in Example 1 except that the types and blending ratios of the materials used were changed as shown in Tables 3-1 to 3-2. The production of urethane pressure-sensitive adhesives and pressure-sensitive adhesive sheets and their evaluation were carried out. Comparative Example 8 is an example in which an adhesive was produced by a one-shot method.

[Evaluation items and methods]
Evaluation items and evaluation methods of the pressure-sensitive adhesive and pressure-sensitive adhesive sheet are as follows.
(Pot life)
The obtained pressure-sensitive adhesive was immediately put into a glass bottle with a lid, and this glass bottle was put into a constant temperature water bath at 40 ° C., and the viscosity of the pressure-sensitive adhesive was measured 1 hour and 6 hours after the start of charging. The viscosity increase rate after 6 hours with respect to 1 hour later (viscosity after 6 hours / viscosity after 1 hour [times]) was determined. The evaluation criteria are as follows.
○: Viscosity increase rate is less than 3 times, good.
Δ: Viscosity increase rate is 3 to 5 times, practical use possible.
X: Viscosity increase rate exceeds 5 times, impractical.

(Initial curability)
A test piece having a width of 30 mm and a length of 100 mm was cut out from the adhesive sheet after curing for 3 hours in an atmosphere of 23 ° C.-50% RH. The test piece was attached to a SUS mesh (aperture: 0.077 mm, wire diameter: 0.05 mm) and then immersed in ethyl acetate. After extracting at 50 degreeC for 24 hours, it dried at 100 degreeC for 30 minutes, and calculated the gel fraction (mass%) based on following formula (1).
Gel fraction (mass%) = (G2 / G1) × 100 (1)
In the above formula, each symbol indicates the following parameter.
G1: mass of the adhesive layer before extraction with ethyl acetate,
G2: mass of the adhesive layer after extraction with ethyl acetate and drying.
The evaluation criteria are as follows.
A: The gel fraction is 80% by mass or more and excellent.
○: The gel fraction is 50% by mass or more and less than 80% by mass, which is good.
(Triangle | delta): A gel fraction is 20 mass% or more and less than 50 mass%, and is practical.
X: The gel fraction is less than 20% by mass, impractical.

(Wettability)
A test piece having a width of 50 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after being cured for one week in an atmosphere of 23 ° C.-50% RH, left for 30 minutes in an atmosphere of 23 ° C.-50% RH, and then peeled off from the test piece. The sheet was peeled off. One end in the longitudinal direction of the test piece from which the release sheet had been peeled was fixed to the end of the glass plate, and the other end that was not fixed was lifted by hand from the surface of the glass plate to a height of 5 cm. In this state, the hands were released, and the time until the entire adhesive layer adhered to the surface of the glass plate was measured. The evaluation criteria are as follows.
A: Less than 4 seconds until adhesion, good.
Δ: 4 seconds or more and less than 8 seconds until adhesion, practical use possible.
X: 8 seconds or more until contact, impractical.

(Base material adhesion)
The adhesive layer of the adhesive sheet after curing for 1 week in an atmosphere of 23 ° C.-50% RH is subjected to 11 half cuts at intervals of 1 mm each in two linear directions orthogonal to each other, and 1 mm square 100 squares were formed. The entire 100 squares were rubbed with a finger for 1 minute, and the number of squares remaining on the base sheet was visually counted. The evaluation criteria are as follows.
A: The number of remaining cells is 81 to 100, which is excellent.
○: The number of remaining cells is 61 to 80, which is good.
Δ: The number of remaining cells is 41 to 60, which is practical.
X: The number of remaining cells is 0 to 40, and cannot be used practically.

(Removability)
Three test pieces having a width of 70 mm and a length of 100 mm were cut out from the pressure-sensitive adhesive sheet after curing for 1 week in an atmosphere of 23 ° C.-50% RH. For each of the three test pieces, the release sheet was peeled off in an atmosphere of 23 ° C.-50% RH, a caustic soda glass plate was attached to the exposed surface of the adhesive layer, and pressure-bonded with a laminator. The obtained three laminates were left in an oven set at 85 ° C.-85% RH for 72 hours (condition 1), 120 hours (condition 2), and 240 hours (condition 3), respectively. Each of the three laminates was taken out of the oven and air-cooled in an atmosphere of 23 ° C.-50% RH for 3 hours, and then the pressure-sensitive adhesive sheet was peeled off from the glass plate, and the removability was evaluated by visual observation. The evaluation criteria are as follows.
A: Excellent with no adhesion layer component adhering to the glass surface under all conditions.
○: Adhesive layer component does not adhere to the glass surface under Conditions 1 and 2, but Adhesive layer component adheres to the glass surface under Condition 3 and is good.
Δ: In condition 1, no adhesion layer component adheres to the glass surface, but in conditions 2 and 3, adhesion layer component adheres to the glass surface, which is practical.
X: Adhesion layer component adheres to the glass surface under all conditions, impractical.

(Adherent contamination suppression)
A test piece having a width of 70 mm and a length of 100 mm was cut out from the pressure-sensitive adhesive sheet after being cured for one week in an atmosphere of 23 ° C.-50% RH, and the release sheet was peeled off in an atmosphere of 23 ° C.-50% RH to expose the adhesive. A caustic soda glass plate was attached to the surface of the layer and pressure-bonded with a laminator. The obtained laminate was left in an oven set at 85 ° C.-85% RH for 72 hours. The laminate was taken out of the oven and air-cooled in an atmosphere of 23 ° C.-50% RH for 3 hours, and then the pressure-sensitive adhesive sheet was peeled off from the glass plate to evaluate adherend contamination. The surface of the glass plate on the side where the adhesive sheet was stuck in the dark room was irradiated with LED (light emitting diode) lamp light and evaluated by visual observation. The evaluation criteria are as follows.
(Double-circle): The adhesion of the adhesion layer component is not seen at all on the glass surface, and it is excellent.
○: Adhesion of a thin adhesive layer component is observed at 1 to 2 locations on the glass surface.
(Triangle | delta): The adhesion of the thin adhesion layer component is seen by three places on the glass surface, and it is practical use.
X: Adhesion of a thin adhesive layer component is observed at 4 or more locations on the glass surface / or adhesion of a thick adhesive layer component is observed at 1 to 2 locations on the glass surface, impractical.

[Evaluation results]
The evaluation results are shown in Tables 4-1 and 4-2.
In Examples 1 to 55, a relatively long-chain polyether polyol (HA) having a number average molecular weight (Mn) per functional group of 1650 or more and a number average molecular weight (Mn) per functional group of 300 or less. A urethane containing a hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of a relatively short-chain active hydrogen group-containing compound (HB) and a polyisocyanate (N), and a polyfunctional isocyanate compound (I) A pressure sensitive adhesive was produced.
In any of these examples, it is possible to produce a pressure-sensitive adhesive having a good pot life and initial curing property, good wettability without adding or reducing a plasticizer, good substrate adhesion, and high temperature and high humidity environment. A pressure-sensitive adhesive sheet having good removability and adherend contamination suppression performance even when exposed underneath could be produced.

As the active hydrogen group-containing compound, a hydroxyl group-terminated urethane prepolymer obtained by using only a plurality of general-purpose polyether polyols (HM) having a number average molecular weight (Mn) per functional group of more than 300 and less than 1650 was used. In Comparative Example 2, since the plasticizer was not added, the obtained pressure-sensitive adhesive sheet had poor wettability.

As the active hydrogen group-containing compound (HX), a relatively long-chain polyether polyol (HA) having a number average molecular weight (Mn) per functional group of 1650 or more and a number average molecular weight (Mn) per functional group In Comparative Examples 1 and 3 to 5 using a hydroxyl group-terminated urethane prepolymer obtained by using a general-purpose polyether polyol (HM) having a molecular weight of more than 300 and less than 1650, a pressure-sensitive adhesive sheet having good wettability without adding a plasticizer Could be manufactured. However, in these comparative examples, a relatively short chain active hydrogen group-containing compound (HB) having a number average molecular weight (Mn) per functional group of 300 or less was not used as a raw material for the hydroxyl group-terminated urethane prepolymer. The pressure-sensitive adhesive had poor pot life and initial curability, and the re-peelability of the pressure-sensitive adhesive sheet and the adherend contamination suppression were poor. The adhesive sheets obtained in these comparative examples also had poor substrate adhesion.

As the active hydrogen group-containing compound (HX), a general-purpose polyether polyol (HM) having a number average molecular weight (Mn) per functional group of more than 300 and less than 1650, and a number average molecular weight (Mn) per functional group of 300. In Comparative Examples 6 and 7 using the hydroxyl group-terminated urethane prepolymer obtained by using the following relatively short-chain active hydrogen group-containing compound (HB), the functional group was added per functional group without the addition of a plasticizer. Since a relatively long-chain polyether polyol (HA) having a number average molecular weight (Mn) of 1650 or more was not used, the obtained pressure-sensitive adhesive sheet had poor wettability. In Comparative Example 6, since the urethane prepolymer obtained by the one-stage polymerization method has a terminal hydroxyl group that is a mixture of primary and secondary, the obtained adhesive has poor initial curability. In Comparative Example 7, since the terminal hydroxyl group of the urethane prepolymer obtained by the two-stage polymerization method is only primary, the initial curability was improved.

In Comparative Example 8, a relatively long-chain polyether polyol (HA) having a number average molecular weight (Mn) per functional group of 1650 or more without using a hydroxyl group-terminated urethane prepolymer (UPH) and a monofunctional group A relatively short chain active hydrogen group-containing compound (HB) having a number average molecular weight (Mn) of 300 or less and a polyfunctional isocyanate compound (I) are mixed to produce a urethane-based pressure-sensitive adhesive by a one-shot method. did. The obtained pressure-sensitive adhesive had poor initial curability, and the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive had poor removability and adherend contamination suppression.

The present invention is not limited to the above-described embodiments and examples, and design changes can be made as appropriate without departing from the spirit of the present invention.

This application claims priority based on Japanese Patent Application No. 2018-0777040 filed on April 12, 2018, the entire disclosure of which is incorporated herein.

10, 20

Adhesive sheet

11, 21

Base sheet

12, 22A,

22B Adhesive layer

13, 23A, 23B Release sheet

Claims

Polyether polyol (HA) having a number average molecular weight of 1650 or more per functional group and an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule having a number average molecular weight of 300 or less per functional group A hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of a plurality of active hydrogen group-containing compounds (HX) containing (HB) and one or more polyisocyanates (N);
A polyfunctional isocyanate compound (I),
The active hydrogen group-containing compound (HB) is a pressure-sensitive adhesive containing an active hydrogen group-containing compound containing only a primary hydroxyl group as an active hydrogen group.
The ratio (NCO / H) of the number of moles of isocyanate groups (NCO) of the polyisocyanate (N) to the total number of moles of active hydrogen groups (H) of the one or more active hydrogen group-containing compounds (HX) is 0. The pressure-sensitive adhesive according to claim 1, which is 20 to 0.84.
The pressure-sensitive adhesive according to claim 1 or 2, wherein the one or more polyether polyols (HA) include a tri- or more functional polyether polyol.
The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the addition amount of the plasticizer (P) is 0 to 10 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH).
The hydroxyl group-terminated urethane prepolymer (UPH) comprises an isocyanate group-terminated urethane prepolymer (UPN), which is a reaction product of a polyether polyol (HA) and a polyisocyanate (N), and an active hydrogen group-containing compound (HB). The pressure-sensitive adhesive according to any one of claims 1 to 4, which is a reaction product.
The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the one or more polyisocyanates (N) contain isophorone diisocyanate.
The pressure-sensitive adhesive according to any one of claims 1 to 6, further comprising at least one alteration inhibitor selected from the group consisting of an antioxidant, a hydrolysis-resistant agent, an ultraviolet absorber, and a light stabilizer. Agent.
The pressure-sensitive adhesive according to any one of claims 1 to 7, further comprising an antistatic agent.
A pressure-sensitive adhesive sheet comprising a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 8.
One or more polyether polyols (HA) having a number average molecular weight of 1650 or more per functional group and one or more polyisocyanates (N) are reacted in an excess ratio of isocyanate groups to obtain isocyanate group-terminated urethane prepolymers. Producing a polymer (UPN);
The obtained isocyanate group-terminated urethane prepolymer (UPN) and one or more active hydrogen group-containing compounds (HB) having a plurality of active hydrogen groups in one molecule having a number average molecular weight of 300 or less per functional group; And reacting
The active hydrogen group-containing compound (HB) is a method for producing a hydroxyl group-terminated urethane prepolymer containing an active hydrogen group-containing compound containing only a primary hydroxyl group as an active hydrogen group.