WO2022004243A1 - Adhesive and adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive that exhibits excellent initial curability, can suppress an increase in adhesive force even when exposed to a hot environment and particularly to a hot, humid environment, and can form an adhesive layer having excellent re-peeling properties. Also provided is an adhesive sheet in which said adhesive is used. The adhesive of the present invention comprises: a hydroxyl group-terminated urethane prepolymer (UPH) that is a reaction product between one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups per molecule, and one or more polyisocyanates (N); and a polyfunctional isocyanate compound (I). The hydrogen group-terminated urethane prepolymer (UHP) is a urethane-based adhesive having a degree of branching of 0.2-0.8 as measured by the GPC-MALS method.

Description

Adhesives and adhesive sheets

The present invention relates to an adhesive and an adhesive sheet.

Conventionally, an adhesive sheet having an adhesive layer formed on a base sheet has been widely used as a surface protective sheet for various members. Examples of the pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive. Acrylic adhesives have excellent adhesive strength, but because of their high adhesive strength, they do not have good removability after being attached to an adherend. Silicone adhesives tend to contaminate the adherend, and silicone resins with relatively low molecular weight may volatilize and adsorb to the surface of devices such as electronic devices, causing problems. On the other hand, the urethane-based adhesive has good adhesion to the adherend, has relatively excellent removability, and is difficult to volatilize.
In the present specification, unless otherwise specified, the "adhesive" is a removable adhesive (removable adhesive), and the "adhesive sheet" is a removable adhesive sheet (removable adhesive sheet). ).

As a method for producing a urethane-based pressure-sensitive adhesive, a method using a hydroxyl group-terminated urethane prepolymer which is a reaction product of an active hydrogen group-containing compound such as a polyol and a polyisocyanate and a polyfunctional isocyanate compound, and a hydroxyl group-terminated urethane prepolymer are used. There is a method (one-shot method) in which the polyol and the polyfunctional isocyanate compound are reacted at once without any reaction.

A general method for producing an adhesive sheet is a coating step of applying an adhesive on a base sheet, and a heat-drying treatment of the formed coating layer to form an adhesive layer containing a cured product of the adhesive. It includes a heating step, a winding step of winding the obtained adhesive sheet around a winding core into a form of an adhesive sheet roll, and a curing step of curing the adhesive sheet roll.

Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (OELDs), as well as touch panel displays that combine such flat panel displays and touch panels, include televisions (TVs), personal computers (PCs), mobile phones, and Widely used in electronic devices such as mobile information terminals.
Urethane-based adhesive sheets include flat panel displays and touch panel displays, as well as substrates (glass substrates and ITO / glass substrates on which an ITO (indium tin oxide) film is formed on glass substrates) manufactured or used in these manufacturing processes. Etc.) and is suitably used as a surface protection sheet for optical members and the like.

Japanese Unexamined Patent Publication No. 11-256124 International Publication No. 2015/141380 Japanese Unexamined Patent Publication No. 2017-193601 International Publication No. 2015/141379

Urethane-based adhesives cure immediately after manufacturing. If the initial curability of the urethane-based pressure-sensitive adhesive is too low, the re-peelability of the pressure-sensitive adhesive layer is lowered, and the components of the pressure-sensitive adhesive layer are likely to adhere to the finger, the adherend, or the like in contact with the pressure-sensitive adhesive layer. In this case, after the adhesive sheet is peeled off from the finger and the adherend, so-called "glue residue" (also referred to as "adhesive contamination") in which the component of the adhesive layer remains on the finger and the adherend is likely to occur. .. The urethane-based pressure-sensitive adhesive preferably has good initial curability.

When the adhesive sheet is exposed to a thermal environment, particularly a moist heat environment, the adhesiveness between the adherend and the adhesive layer becomes high, and as a result, the adhesive strength of the adhesive layer increases and the removability tends to decrease. There is. It is preferable that the pressure-sensitive adhesive sheet has good re-peelability even when exposed to a thermal environment, particularly a moist heat environment, and there is no adherent contamination in which the components of the adhesive layer remain on the surface of the adherend after re-peeling.

Patent Documents 1 to 4 are mentioned as a related technique of the present invention.
Patent Document 1 comprises an aqueous dispersion containing a polymer of a monomer containing a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as a main component, and the polymer has a weight average molecular weight of 250. Disclosed is a water-dispersible pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) for re-peeling, which has more than 10,000 and has 5 or less branches per polymer molecule at a molecular weight of 5 million (claim 1).

In Patent Document 2,
(A) Obtained by copolymerizing a monomer component containing a (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms and a carboxyl group-containing monomer, and gel permeation chromatography method / multi-angle laser light scattering detection. A (meth) acrylic copolymer having a branching degree of 0.55 or less and an acid value of 0.1 to 7.8 mgKOH / g as measured by a device (GPC-MALS).
(B1) Isocyanate compound and
(B2) A pressure-sensitive adhesive composition for a polarizing plate (acrylic pressure-sensitive adhesive) containing a metal chelate compound is disclosed (claim 1).

Patent Document 3 discloses a photocurable pressure-sensitive adhesive precursor composition containing an ethylenically unsaturated monomer, a prepolymer having a monomer unit derived from a hydrogen-donating monomer, and a hydrogen-drawing type photoinitiator. (Claim 1).
The ethylenically unsaturated monomer is preferably (meth) acrylate (paragraph 0021).
The hydrogen donating monomer preferably has an ethylenically unsaturated double bond and at least one selected from the group consisting of an amino group, an amide group, a hydroxyl group, a thiol group, a heterocycle, and an alkylene oxide chain (claim). 2).
Patent Document 3 discloses a photocurable pressure-sensitive adhesive containing a randomly branched (co) polymer having a branching degree of 0.25 or more and 0.44 or less (claim 5).
In Examples 1 to 3 of Patent Document 3, an acrylic pressure-sensitive adhesive is produced.

Patent Document 4 describes (A) obtained by copolymerizing a monomer component containing a (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms and a hydroxyl group-containing monomer, and a gel permeation chromatography method / poly. A pressure-sensitive adhesive composition for a polarizing plate containing a (meth) acrylic copolymer having a branching degree of 0.55 or less as measured by an angular laser light scattering detector (GPC-MALS) and (B) an isocyanate compound. (Acrylic adhesive) is disclosed (claim 1).
The reference numerals of the respective components described in Patent Documents 1 to 4 are the reference numerals described in these documents and have nothing to do with the reference numerals used for the respective components of the present invention.

Patent Documents 1 to 4 describe the number of branches or the degree of branching of the acrylic (co) polymer. None of these patent documents relate to acrylic pressure-sensitive adhesives and not urethane-based pressure-sensitive adhesives. There is no document describing the degree of branching of the prepolymer or its raw material in urethane-based pressure-sensitive adhesives.

The present invention has been made in view of the above circumstances, has good initial curability, suppresses an increase in adhesive strength even when exposed to a thermal environment, particularly a moist thermal environment, and has good removability. It is an object of the present invention to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet using the same.

The pressure-sensitive adhesive of the present invention
A hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N).
A pressure-sensitive adhesive containing the polyfunctional isocyanate compound (I).
The hydroxyl group-terminated urethane prepolymer (UPH) is a urethane-based pressure-sensitive adhesive having a branching degree of 0.2 to 0.8 as measured by the GPC-MALS method.

In the pressure-sensitive adhesive of the first embodiment according to the present invention.
The active hydrogen group-containing compound (H) of one or more kinds contains 50% by mass or more of the active hydrogen group-containing compound (HX) having a branching degree of 0.5 or less as measured by the GPC-MALS method.
The hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of 0.2 to 0.6 as measured by the GPC-MALS method.

In the pressure-sensitive adhesive of the second embodiment according to the present invention.
The active hydrogen group-containing compound (H) of one or more kinds contains 50% by mass or more of the active hydrogen group-containing compound (HY) having a branching degree of more than 0.5 as measured by the GPC-MALS method.
The hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of more than 0.6 and 0.8 or less as measured by the GPC-MALS method.

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

According to the present invention, it is possible to form an adhesive layer having good initial curability, suppressing an increase in adhesive force even when exposed to a thermal environment, particularly a moist thermal environment, and having good removability. A pressure-sensitive adhesive and a pressure-sensitive adhesive sheet using the same can be provided.
According to the first embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a moist thermal environment are good, and further, the base material is formed. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good adhesion, scratch resistance, and curved surface adhesion, and a pressure-sensitive adhesive sheet using the same.
According to the second embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a moist thermal environment are good, and further, folding resistance is good. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good properties, cutability, and heat resistance, and a pressure-sensitive adhesive sheet using the same.

It is a schematic cross-sectional view of the pressure-sensitive adhesive sheet of 1st Embodiment which concerns on this invention. It is a schematic cross-sectional view of the pressure-sensitive adhesive sheet of the 2nd Embodiment which concerns on this invention. It is an image diagram of the production example of a prepolymer.

[Adhesive]
The pressure-sensitive adhesive of the present invention
A hydroxyl group-terminated urethane prepolymer (UPH) (simply) which is a reaction product of one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N). Also called "prepolymer"),
A pressure-sensitive adhesive containing the polyfunctional isocyanate compound (I).
The hydroxyl group-terminated urethane prepolymer (UPH) is a removable urethane-based adhesive having a branching degree α (also simply referred to as “branching degree α”) measured by the GPC-MALS method of 0.2 to 0.8. It is an agent.
The pressure-sensitive adhesive sheet of the present invention is a urethane-based pressure-sensitive adhesive sheet containing a base material sheet and a pressure-sensitive adhesive layer made of the cured product of the above-mentioned pressure-sensitive adhesive of the present invention.

"Branch degree α" is a device ("GPC-MALS" or "GPC-MALS-VISCO") that combines a gel permeation chromatograph (GPC) with a multi-angle light scattering detector (MALS) and a viscosity detector (VISCO). It is also measured by a known method. For the measurement of the degree of branching α by GPC-MALS, refer to Patent Documents 1 to 4 mentioned in the section of [Background Art].

The GPC method is a method in which a solution of a sample whose molecular weight is to be measured is passed through a column filled with a porous material such as silica, and the molecular weight is measured by the elution time. The smaller the molecular size of the sample, the longer the elution time because it passes through the deeper part of the pores of the porous material. The molecular weight of the sample is determined by comparing the elution time with a standard material with a known molecular weight.
The length of the elution time of the sample in the GPC method corresponds to the magnitude of the molecular size, but the magnitude of the molecular size does not strictly correlate with the magnitude of the molecular weight. Since the molecular size changes depending on the affinity with the eluent, the molecular weight cannot be measured accurately depending on the polarity of the sample. The molecular size also depends on the branching state of the molecule. Even if the molecular weight is the same, the more branches there are, the smaller the molecular size. Even if the samples have the same elution time, the actual molecular weight (absolute molecular weight) may differ depending on the polarity or the branching state of the molecule, but in the GPC method, the samples with the same elution time have the same measured molecular weight. It ends up.

In GPC-MALS, in addition to normal GPC measurement, the sample solution is irradiated with laser light of a specific wavelength, and the scattered light intensity generated by Rayleigh scattering is measured. The scattered light intensity depends on the molecular size and the branching state. For example, in the case of a sample having a small molecular size and no branching, the sample has one scattering point and the scattered light intensity is low. If the sample has a large molecular size and many branches, the number of scattered points is large and the scattered light intensity is high. In GPC-MALS, the intrinsic viscosity of the sample is also measured by VISCO. In GPC-MALS, it is also possible to determine the absolute molecular weight.

The relationship between the intrinsic viscosity, the density, the weight average molecular weight (Mw), and the degree of branching α is expressed by the calculation formula (the following formula) of Mark-Houwink-Sakurada.

In the formula, log [η] indicates intrinsic viscosity, logK indicates density, Mw indicates weight average molecular weight, and α indicates degree of branching. In the (pre) polymer molecule, the smaller the α value, the more branches (high branch), and the shape becomes spherical or close to it (generally in the range of α <0.5), and the larger the α value, the more branches. Less (low branch), rod-shaped or close to it (generally in the range α> 0.8).

For example, as shown in FIG. 3, 3 molecules of a relatively high-branched polyol (PO1), 5 molecules of a relatively low-branched polyol (PO2), and 7 molecules of a relatively low-branched polyisocyanate (PI1). When reacting with, a relatively high-branched prepolymer (PP1), a relatively low-branched prepolymer (PP2), or an intermediate prepolymer in a branched state may be produced. The prepolymer (PP1) and the prepolymer (PP2) have the same molecular weight, but different branching states, and different molecular sizes and molecular morphologies. Note that FIG. 3 is an image diagram of a reaction example.
As described in the section [Problems to be Solved by the Invention], conventionally, there is no document describing the degree of branching α of the prepolymer or its raw material in the urethane-based pressure-sensitive adhesive.
In the present invention, the degree of branching α of the prepolymer or its raw material is optimized, and the characteristics of the pressure-sensitive adhesive are optimized.
The degree of branching α of the prepolymer can be adjusted by the degree of branching α of each of the plurality of raw materials used, the combination of the plurality of raw materials used, the amount ratio of the plurality of raw materials used, the reaction conditions, the reaction procedure, and the like.

The hydroxyl group-terminated urethane prepolymer (UPH) contained in the pressure-sensitive adhesive of the present invention has a branching degree α of 0.2 to 0.8.
When the degree of branching α is less than 0.2, the prepolymer molecule has many branches (highly branched) and has a spherical shape or a shape close to it. The pressure-sensitive adhesive containing a highly branched hydroxyl-terminal urethane prepolymer (UPH) causes an excessive intramolecular reaction to proceed during the reaction between the hydroxyl-terminal urethane prepolymer (UPH) and the curing agent, thereby suppressing the progress of the intermolecular cross-linking reaction. Therefore, the initial curability tends to decrease. Further, the re-peelability of the adhesive layer is lowered mainly in the portion where the degree of intramolecular cross-linking is low, and after the adhesive sheet is peeled off from the finger and the adherend, the component of the adhesive layer remains on the finger and the adherend. "Glue residue" (also called "adhesive contamination") is likely to occur. In addition, when exposed to a thermal environment, particularly a moist thermal environment, the adhesive strength increases significantly and the removability tends to decrease.

When the degree of branching α is more than 0.8, the prepolymer molecule has few branches (low branching) and has a rod shape or a shape close to it. Adhesives containing low-branched hydroxyl-terminal urethane prepolymers (UPH) have a rod-like or similar shape, which makes it difficult to form a high-density crosslinked structure and reduces initial curability. It's easy to do. Further, as a result of insufficient cross-linking structure, the removability of the adhesive layer is lowered, and after the adhesive sheet is peeled off from the finger and the adherend, the component of the adhesive layer remains on the finger and the adherend and the like. "Glue residue" (adhesive contamination) is likely to occur. In addition, when exposed to a thermal environment, particularly a moist thermal environment, the adhesive strength increases significantly and the removability tends to decrease.

By using a hydroxyl group-terminated urethane prepolymer (UPH) having a degree of branching α in the range of 0.2 to 0.8, an intramolecular reaction and a molecule occur during the reaction between the hydroxyl group-terminated urethane prepolymer (UPH) and the curing agent. Since the cross-linking reaction proceeds moderately and a high-density cross-linking structure is formed at an early stage, the initial curability is good, and the increase in adhesive strength is suppressed even when exposed to a thermal environment, especially a moist thermal environment. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good removability.

(First Embodiment)
In the pressure-sensitive adhesive of the first embodiment of the present invention, one or more active hydrogen group-containing compounds (H) are active hydrogen group-containing compounds having a branching degree α of 0.5 or less as measured by the GPC-MALS method. The hydroxyl group-terminated urethane prepolymer (UPH) containing 50% by mass or more of (HX) has a branching degree α of 0.2 to 0.6 as measured by the GPC-MALS method.
In the pressure-sensitive adhesive of the first embodiment, since the intramolecular cross-linking reaction proceeds early and predominantly while maintaining the progress of the intermolecular cross-linking reaction, it is exposed to the initial curability and the thermal environment, particularly the moist heat environment. It has good re-peelability (effect of suppressing increase in adhesive strength), and it is possible to achieve both a dense structure due to intramolecular cross-linking and a sparse structure due to intermolecular cross-linking. It is possible to form an adhesive layer having good scratch resistance and curved surface adhesion.

Since the above-mentioned action and effect can be effectively obtained in the pressure-sensitive adhesive of the first embodiment, the hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree α measured by the GPC-MALS method of 0.3 to 0. It is preferably 6 and more preferably 0.4 to 0.6.

Since the above-mentioned action and effect can be effectively obtained in the pressure-sensitive adhesive of the first embodiment, one or more active hydrogen group-containing compounds (H) have a branching degree α of 0.5 as measured by the GPC-MALS method. The following active hydrogen group-containing compound (HX) is contained in an amount of 50% by mass or more and less than 100% by mass, and the active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5 as measured by the GPC-MALS method is 0. It is preferable to contain more than 50% by mass and less than 50% by mass.
When the active hydrogen group-containing compound (H) satisfies the above-mentioned regulation, the contrast between the sparse part and the dense part of the urethane bond produced becomes stronger, so that the above-mentioned action and effect due to the expression of the sea-island structure are effectively enhanced. ..

Since the above-mentioned action and effect can be effectively obtained in the pressure-sensitive adhesive of the first embodiment, one or more active hydrogen group-containing compounds (H) have a branching degree α of 0.3 as measured by the GPC-MALS method. It is preferable to include the following active hydrogen group-containing compound (HX-S), and more preferably to contain an active hydrogen group-containing compound having a branching degree α of 0.2 or less.

The pressure-sensitive adhesive of the first embodiment more preferably contains 70% by mass or more of one or more active hydrogen group-containing compounds (HX) having a branching degree α of 0.5 or less. The pressure-sensitive adhesive of the first embodiment more preferably contains more than 0% by mass and less than 30% by mass of one or more active hydrogen group-containing compounds (HY) having a branching degree α of more than 0.5 by 10% by mass. It is particularly preferable to contain less than 30% by mass.
When the active hydrogen group-containing compound (H) satisfies the above-mentioned regulations, a tighter urethane bond is formed, and the above-mentioned action and effect due to the expression of the sea-island structure are effectively enhanced.

(Second Embodiment)
In the pressure-sensitive adhesive of the second embodiment of the present invention, one or more active hydrogen group-containing compounds (H) are active hydrogen group-containing compounds having a branching degree α of more than 0.5 as measured by the GPC-MALS method. The hydroxyl group-terminated urethane prepolymer (UPH) containing 50% by mass or more of (HY) has a branching degree α measured by the GPC-MALS method of more than 0.6 and 0.8 or less.
In the pressure-sensitive adhesive of the second embodiment, the crosslinked structure is formed at an early stage by the appropriate branched structure contained in the hydroxyl group-terminated urethane prepolymer (UPH), so that the adhesive is exposed to initial curability and a thermal environment, particularly a moist thermal environment. It is possible to form an adhesive layer having good re-peelability (effect of suppressing an increase in adhesive force) when it is used. The pressure-sensitive adhesive of the second embodiment also forms a structure having a relatively sparse crosslink density, so that a pressure-sensitive adhesive layer having good folding resistance, cutting resistance, and heat resistance can be formed.

In the pressure-sensitive adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above-mentioned action and effect can be effectively obtained. Therefore, the hydroxyl group-terminated urethane prepolymer (UPH) is branched as measured by the GPC-MALS method. It is more preferable that the degree α is 0.7 to 0.8.

In the pressure-sensitive adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above-mentioned action and effect can be effectively obtained. Therefore, one or more active hydrogen group-containing compounds (H) are prepared by the GPC-MALS method. The active hydrogen group-containing compound (HY) having a measured degree of branching α of more than 0.5 is contained in an amount of 50% by mass or more and less than 100% by mass, and the degree of branching α measured by the GPC-MALS method is 0.5 or less. It is preferable to contain the active hydrogen group-containing compound (HX) in an amount of more than 0% by mass and less than 50% by mass.

In the pressure-sensitive adhesive of the second embodiment, a uniform and appropriate crosslinked structure is formed, and the above-mentioned action and effect can be effectively obtained. Therefore, one or more active hydrogen group-containing compounds (H) are prepared by the GPC-MALS method. It is preferable to contain 50% by mass or more of the active hydrogen group-containing compound (HY-L) having a measured degree of branching α of more than 0.6.

In the pressure-sensitive adhesive of the second embodiment, it is more preferable that the branching degree α of the active hydrogen group-containing compound (HY) is 0.8 or more.
The pressure-sensitive adhesive of the second embodiment more preferably contains 70% by mass or more of one or more active hydrogen group-containing compounds (HY). The pressure-sensitive adhesive of the second embodiment preferably contains one or more active hydrogen group-containing compounds (HX) having a branching degree α of 0.5 or less in an amount of more than 0% by mass and less than 30% by mass, more preferably 10% by mass or more. It is particularly preferable to contain less than 30% by mass.

(Hydroxy group terminal urethane prepolymer (UPH))
The hydroxyl group-terminated urethane prepolymer (UPH) is a reaction product obtained by copolymerizing one or more active hydrogen group-containing compounds (H) with one or more polyisocyanates (N). The copolymerization reaction can be carried out in the presence of one or more catalysts, if necessary. If necessary, one or more kinds of solvents can be used for the copolymerization reaction.
In the present invention, the degree of branching α of each of the plurality of raw materials used, the combination of the plurality of raw materials used, the amount ratio of the plurality of raw materials used, the reaction conditions, the reaction procedure, etc. are adjusted to obtain a hydroxyl group-terminated urethane prepolymer (UPH). The degree of branching α of is in the range of 0.2 to 0.8.

In the pressure-sensitive adhesive of the first embodiment, the weight average molecular weight (Mw) of the hydroxyl group-terminated urethane prepolymer (UPH) is preferably 40,000 or more, more preferably 60,000 or more, and particularly preferably 80,000 or more. When Mw is at least the above lower limit, the initial curability and the removability are good.

In the pressure-sensitive adhesive of the second embodiment, the weight average molecular weight (Mw) of the hydroxyl group-terminated urethane prepolymer (UPH) is preferably 10,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more. When Mw is at least the above lower limit, the initial curability, removability, and heat resistance are good.

<Active hydrogen group-containing compound (H)>
The active hydrogen group-containing compound (H) is a compound having a plurality of active hydrogen groups in one molecule.
Examples of the active hydrogen group include a hydroxyl group (hydroxy group), a mercapto group, an amino group (in the present specification, the amino group includes an imino group) and the like. Examples of the active hydrogen group-containing compound (H) include a polyol having a plurality of hydroxyl 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, and one molecule. Examples thereof include polythiol having a plurality of mercapto groups. These active hydrogen group-containing compounds (H) may be non-polymers or polymers. These can be used alone or in combination of two or more.
Of these, polyols are preferred. Since polyamines and polythiols are highly reactive with polyisocyanates and have a short pot life, they are preferably used in combination with polyols.

Examples of the polyol that can be used as the active hydrogen group-containing compound (H) include polyester polyols, polyether polyols, polyacrylic polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. Among them, polyester polyols, polyether polyols, and combinations thereof are preferable because they have appropriate flexibility and the adhesive strength, folding resistance, and curved surface adhesion of the adhesive layer are suitable. Further, it is particularly preferable that the one or more active hydrogen group-containing compounds (H) contain a polyether polyol because the hydrolysis resistance becomes preferable.

As the polyester polyol that can be used as the active hydrogen group-containing compound (H), known ones can be used. Examples of the polyester polyol include a compound (esterified product) obtained by an esterification reaction between one or more polyol components and one or more acid components.

As the polyol component of the raw material, 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, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol and the like can be mentioned. Be done.

The acid components of the raw material include succinic acid, methylsuccinic acid, adipic acid, piceric 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 their acid anhydrides. And so on.

As the polyether polyol that can be used as the active hydrogen group-containing compound (H), known ones can be used. Examples of the polyether polyol include compounds (addition polymers) obtained by addition-polymerizing one or more kinds of oxylan compounds using an active hydrogen group-containing compound having a plurality of active hydrogen groups in one molecule as an initiator. ..

Examples of the initiator include hydroxyl group-containing compounds and amines. Specifically, 2 such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine. Functional initiators; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamines.
Examples of the oxylan compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); tetrahydrofuran (THF) and the like.

As the polyether polyol, an alkylene oxide adduct (also referred to as a polyoxyalkylene polyol) of an active hydrogen group-containing compound is preferable. Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), PPG (PPG-EO) having ethylene oxide (EO) added to the end, and polyalkylene glycol such as polytetramethylene glycol; A trifunctional polyether polyol such as an alkylene oxide adduct of glycerin is preferable.

Examples of the polyamine that can be used as the active hydrogen group-containing compound (H) include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, and 1,6. -Hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonandiamine, 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-Aminopropane, 3-Aminomethyl-3,3,5-trimethyl-Cyclohexylamine, Norbornan skeleton Dimethyleneamine, Metaxylylene diamine (MXDA), Hexamethylenediaminecarbamate, Diethylenetriamine, Triethylenetetramine, Tetraethylenepenta Aliphatic polyamines such as min and 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-phenylene Diamine, p-phenylenediamine, 2,3-tolylene diamine, 2,4-tolylene diamine, 2,5-tolylene diamine, 2,6-tolylene diamine, 3,4-tolylene diamine, and diethyltoluene Aromatic polyamines such as diamines; and the like.

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

Examples of the polythiothane that can be used as the active hydrogen group-containing compound (H) include methanedithiorane, 1,3-butanedithiole, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiole, 1, 3-benzenedithiol, 1,4-benzenedithiol, 1,10-decandithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonandithiol, 1,8-octanedithiol, 1,5 -Pentanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1,2- Ethanedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4'-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiathiozole, 1,8 -Dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, 2-di-n-butylamino-4,6-dimercapto-s-triazine, and thiol group-terminal polymers (polysulfide polymers, etc.) And so on.

The active hydrogen group-containing compound (H) of one or more kinds can include a bifunctional active hydrogen group-containing compound and / or a trifunctional or more active hydrogen group-containing compound. In general, a bifunctional active hydrogen group-containing compound has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer. The trifunctional or higher active hydrogen group-containing compound has three-dimensional crosslinkability and can impart appropriate hardness to the adhesive layer. By selecting the number of functional groups (number of active hydrogen groups) of each active hydrogen group-containing compound (H), properties such as adhesive strength, cohesive strength, and removability of the urethane-based pressure-sensitive adhesive can be adjusted. The number of functional groups of each material can be selected so that the properties such as adhesive strength, cohesive strength, and removability are in a preferable range depending on the application and the like.
Since it is easy to achieve both adhesive strength and removability, the active hydrogen group-containing compound (H) of one or more kinds includes a bifunctional active hydrogen group-containing compound and a trifunctional or more active hydrogen group-containing compound. Is preferable.

The active hydrogen group-containing compound (H) is preferably an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less measured by the GPC-MALS method, and a branch measured by the GPC-MALS method. Contains an active hydrogen group-containing compound (HY) having a degree α of more than 0.5.
The degree of branching α of the active hydrogen group-containing compound (H) can be adjusted by the structure of the plurality of raw materials used, the amount ratio of the plurality of raw materials used, the combination of the plurality of raw materials used, the reaction conditions, the reaction procedure, and the like. ..
Even if the raw material composition is the same, if the molecular weight of the active hydrogen group-containing compound (H) changes, the degree of branching α changes. Even if the active hydrogen group-containing compound (H) has the same molecular weight, the degree of branching α changes if the branching structure changes. The number of functional groups of the active hydrogen group-containing compound (H) may change depending on the composition if the branched structure is changed.

The number of functional groups of the active hydrogen group-containing compound (H) is not particularly limited. The number of functional groups of the active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less is preferably trifunctional or higher from the viewpoint that a highly branched structure can be easily obtained. The number of functional groups of the active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5 is preferably bifunctional or less from the viewpoint that a low-branching structure can be easily obtained.

The number average molecular weight (Mn) of the active hydrogen group-containing compound (H) is not particularly limited. The Mn of the active hydrogen group-containing compound (H) is preferably 50 to 20000, more preferably 100 to 15000, and particularly preferably 400 to 10000, because the adhesive strength and wettability of the adhesive layer are suitable.
The Mn of the active hydrogen group-containing compound (H) affects the degree of branching α. However, as described above, the degree of branching α is also affected by factors other than Mn.

The active hydrogen group-containing compound (H) preferably contains an active hydrogen group-containing compound having a primary hydroxyl group. In this case, the initial curability of the pressure-sensitive adhesive can be improved.

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

Examples of the aromatic polyisocyanate include 1,3-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, and 2,6-triisocyanate. Range isocyanate, 4,4'-toluidin diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanatebenzene, dianisidine diisocyanate, 4,4'-diphenylether 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-Tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylenediocyanate, 1,3-butylenediocyanate, and dodecamethylene diisocyanate. , And 2,4,4-trimethylhexamethylene diisocyanate.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, and methyl-2,6. -Cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatemethyl) cyclohexane and the like can be mentioned.

Other examples of the polyisocyanate include the trimethylolpropane adduct body, the biuret body, the allophanate body, and the trimer of the polyisocyanate (the trimer contains an isocyanurate ring) and the like.

The preferred raw material compounding ratio of the hydroxyl group-terminated urethane prepolymer (UPH) is as follows.
The ratio of the number of moles of the isocyanate group (NCO) of the polyisocyanate (N) to the total number of moles of the active hydrogen groups (H) of the plurality of active hydrogen group-containing compounds (H) (NCO / H ratio) is 0. It is preferable to determine the raw material compounding ratio so as to be 20 to 0.95, preferably 0.40 to 0.85. The closer the NCO / H ratio is to 1, the more likely it is to gel during the synthesis of the hydroxyl group-terminated urethane prepolymer (UPH). When the NCO / H ratio is 0.95 or less, gelation during synthesis of the hydroxyl group-terminated urethane prepolymer (UPH) can be effectively suppressed.

<Catalyst>
If necessary, one or more catalysts can be used for the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH). Known catalysts can be used, and examples thereof include tertiary amine compounds and organometallic compounds.
Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU) and the like.
Examples of the organometallic compound include tin-based compounds and non-tin-based compounds.
Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimalate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dioctyltin dilaurate, dibutyltin sulfide, tributyltin sulfide, and tributyltin oxide. , Tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate and the like.
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-based such as iron ethylhexanoate and iron acetylacetonate; cobalt-based such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc-based such as zinc naphthenate and zinc 2-ethylhexanoate; A zirconium system can be mentioned.
The type and amount of the catalyst added can be appropriately designed within a range in which the reaction proceeds well.

When a plurality of types of active hydrogen group-containing compounds (H) having different reactivity are used in combination, there is a risk that the difference in reactivity may cause poor polymerization stability or cloudiness of the reaction solution in a single catalyst system. be. In this case, by using two or more kinds of catalysts, it is easy to control the reaction (for example, reaction rate), and the above problem can be solved. In a system in which a plurality of types of active hydrogen group-containing compounds (H) having different reactivity are used in combination, it is preferable to use two or more types of catalysts. The combination of two or more kinds of catalysts is not particularly limited, and examples thereof include tertiary amine / organometallic, tin-based / non-tin-based, and tin-based / tin-based. It is preferably tin-based / tin-based, more preferably dioctyl tin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dioctyltin dilaurate (tin 2-ethylhexanoate / dioctyltin dilaurate) is not particularly limited, preferably more than 0 and less than 1, more preferably 0.2 to 0.8. be. When the mass ratio is less than 1, the balance of catalytic activity is good, gelation and cloudiness of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

The amount of one or more catalysts used is not particularly limited, and is preferably 0.01 to 0.01 with respect to the total amount of one or more active hydrogen group-containing compounds (H) and one or more polyisocyanates (N). It is 1.0% by mass.

<Solvent>
If necessary, one or more kinds of solvents can be used for the polymerization of the hydroxyl group-terminated urethane prepolymer (UPH). Known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene and the like are particularly preferable from the viewpoint of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

<Polymerization method of hydroxyl group-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 the hydroxyl group-terminated urethane prepolymer (UPH),
Procedure 1) One or more active hydrogen group-containing compounds (H), one or more polyisocyanates (N), one or more catalysts as needed, and one or more solvents as needed. Procedure for filling in a flask;
Step 2) One or more active hydrogen group-containing compounds (H), one or more catalysts as needed, and one or more solvents as needed are placed in a flask, and one or more polyisocyanates (1 or more polyisocyanates) are charged therein. Examples thereof include a procedure for dropping and adding N).
In the polymerization method of step 1), the reaction may partially and rapidly proceed to form a polymer having a low degree of branching as a main component, or a gel may be formed. On the other hand, in the polymerization method of step 2), the reaction can be controlled mildly, and a polymer having a preferable degree of branching can be easily produced. Therefore, the polymerization method of step 2) is more preferable.

When a plurality of active hydrogen group-containing compounds (H) and / or polyisocyanates (N) are used, the reaction may be carried out in a plurality of steps.
For example, in the reaction example shown in FIG. 3, a relatively high-branched polyol (PO1), a relatively low-branched polyol (PO2), and a relatively low-branched polyisocyanate (PI1) are collectively reacted. In this case, it is highly possible that a prepolymer in a branched state intermediate between the relatively high-branched prepolymer (PP1) and the relatively low-branched prepolymer (PP2) is produced. A relatively high-branched polyol (PO1) and a relatively low-branched polyisocyanate (PI1) are first reacted, and then a relatively low-branched polyol (PO2) is reacted to cause a relatively high-branched pre. It becomes easier to obtain a polymer.

When a 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 becomes difficult to control the reaction rate, polymerization stability, etc., 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.

(Polyfunctional isocyanate compound (I))
As the polyfunctional isocyanate compound (I), a known compound can be used, and the compound exemplified as the polyisocyanate (N) which is a raw material of the hydroxyl group-terminated urethane prepolymer (UPH) (specifically, aromatic polyisocyanate and aliphatic). Polyisocyanates, aromatic aliphatic polyisocyanates, alicyclic polyisocyanates, and trimethylolpropane adducts / biuret / allophanate / trimerics thereof can be used.

The blending amount of the polyfunctional isocyanate compound (I) is not particularly limited. The ratio (NCO / H ratio) of the number of moles of the isocyanate group (NCO) of the polyisocyanate (I) to the total number of moles of the active hydrogen group (H) of the hydroxyl group-terminated urethane prepolymer (UPH) is 0.20 to 4 It is preferable to determine the raw material compounding ratio so as to be 0.00, preferably 0.40 to 3.00.

(Plasticizer (P))
From the viewpoint of reducing the adhesive strength of the adhesive layer and improving the wettability, the adhesive of the present invention may further contain one or more plasticizers (P), if necessary. The plasticizer (P) is not particularly limited, and an organic acid ester is preferable from the viewpoint of compatibility with other components.

The content of the plasticizer (P) is preferably 10 parts by mass or more with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). The upper limit of the content of the plasticizer (P) is not particularly limited, and is preferably 300 parts by mass or less, more preferably 150 parts by mass or less. When the content of the plasticizer (P) is within the above range, the removability is good.

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

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

Examples of the ester of monobasic acid or polybasic acid and polyalkylene glycol include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurylate, polyethylene glycol dioleate, and dipolyethylene glycol adipate. Examples include ether.

From the viewpoint of improving wettability, the molecular weight (formula 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 may contain one or more kinds of solvents, if necessary. Known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene and the like are particularly preferable from the viewpoint of the solubility of the hydroxyl group-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

(Change of state inhibitor)
The pressure-sensitive adhesive of the present invention may contain one or more kinds of anti-deterioration agents, if necessary. This makes it possible to suppress deterioration of various properties due to long-term use of the adhesive layer. Examples of the alteration inhibitor include a hydrolysis resistant agent, an antioxidant, an ultraviolet absorber, a light stabilizer and the like.

<Hydrolytic agent>
When a hydrolysis reaction occurs in the adhesive layer in a (wet) thermal environment or the like to generate a carboxy group, a hydrolysis resistant agent can be used to block the carboxy group. Examples of the hydrolysis resistant agent include carbodiimide-based, oxazoline-based, and epoxy-based. Of these, the carbodiimide system is preferable from the viewpoint of the hydrolysis inhibitory effect.

A carbodiimide-based hydrolysis resistant agent 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 decarboxylating and condensing diisocyanate in the presence of a carbodiimidization catalyst. Here, examples of the diisocyanate include 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-toluene diisocyanate, 2,6-toluene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, Examples thereof include 4,4'-dicyclohexylmethane diisocyanate and tetramethylxylylene diisocyanate. Examples of the carbodiimidization catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, and 1-ethyl-. Examples thereof include 2-phospholene-1-oxide and phosphorene oxides such as these 3-phosphoren isomers.

Examples of the oxazoline-based hydrolysis resistant agent 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), 2,2'-diphenylenebis (2-oxazoline) and the like can be mentioned.

Examples of the epoxy-based hydrolysis resistant agent include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, and 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, sebacic acid and the like. Aliphatic or aromatic polyvalent carboxylic acid diglycidyl esters or polyglycidyl esters; resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane, tris- (p) Diglycidyl ethers or polyglycidyl ethers of polyvalent phenols such as -hydroxyphenyl) methane and 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane; N, N-diglycidylaniline, N, N-di N-glycidyl derivatives of amines such as glycidyl toluidine and N, N, N', N'-tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl derivatives of aminophenols; triglycidyltris (2-hydroxyethyl) ) Isocyanurate and triglycidyl isocyanurate; examples thereof include epoxy resins such as orthocresol type epoxy resin and phenol novolac type epoxy resin.

The amount of the hydrolysis resistant agent added 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 preferably, it is 0.5 to 3 parts by mass.

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

Examples of the phenolic compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stear-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-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2- [Β- (3-t-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane, 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) butyl acid] glycol ester, 1,3,5-tris (3' ', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol and the like can be mentioned.

Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and disstearyl 3,3'-thiodipropionate.

Examples of the phosphorus compound include triphenylphosphite, diphenylisodecylphosphite, 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-Phenylphophenylanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10 -Desiloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert) -Butylphenyl) Phenyl Phenyl, Cyclic Neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) Phenyl Phenyl, and 2,2-Methylenebis (4,6-di-tert-butylphenyl) ) Octylphosphite and the like can be mentioned.

By using an antioxidant, it is possible to prevent thermal deterioration of the hydroxyl group-terminated urethane prepolymer (UPH).
The amount of the antioxidant added is not particularly limited, and is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and particularly preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). Is 0.2 to 2 parts by mass.

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

<UV absorber>
Examples of the ultraviolet absorber include benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, oxalic acid anilides-based compounds, cyanoacrylate-based compounds, and triazine-based compounds.
The amount of the ultraviolet absorber added does not inhibit the initiation and progress of the polymerization of the radically polymerizable monomer (MX) by irradiation with active energy rays, and is easily radicalized by the light of a fluorescent lamp and ambient light such as sunlight. It can be appropriately designed as long as the reaction of the polymerizable monomer (MX) is not started. When the radically polymerizable monomer (MX) is ultraviolet curable, the amount of the ultraviolet absorber added is designed according to the type of the ultraviolet absorber, the wavelength range of the ultraviolet rays applied to the adhesive layer, and the integrated amount of light. Will be done. The amount of the ultraviolet absorber added is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2.5 parts by mass, and particularly preferably 0, with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH). .2 to 2 parts by mass.

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

(Antistatic agent (AS))
The pressure-sensitive adhesive of the present invention may contain one or more antistatic agents (AS), if necessary. Examples of the antistatic agent (AS) include inorganic salts, ionic liquids, ionic solids, and surfactants, and among them, ionic liquids and ionic solids are preferable. The "ionic liquid" is also called a room temperature molten salt, which is a salt having fluidity at 25 ° C.

Examples of the inorganic salt 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 and sodium nitrate. , Sodium carbonate, sodium thiocyanate and the like.

Ion solutions containing imidazolium ions include, for example, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, and 1-butyl. -3-Methylimidazolium bis (trifluoromethylsulfonyl) imide and the like can be mentioned.

Examples of the ionic liquid containing pyridinium ion include 1-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-butylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexylpyridinium bis (trifluoromethylsulfonyl) imide, and the like. 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-methylpyridinium bis (perfluorobutylsulfonyl) ) Imid and the like.

Examples of the ionic liquid containing ammonium ions include 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, trimethylheptyl ammoniumbis (trifluoromethanesulfonyl) imide, and 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 (trifluoromethane) Examples thereof include sulfonyl) imide and tri-n-butylmethylammonium bistrifluoromethanesulfonimide.

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

An ionic solid is a salt of a cation and an anion like an ionic liquid, but is a substance that exhibits the properties of a solid at 25 ° C under normal pressure. As the cation, for example, alkali metal ion, phosphonium ion, pyridinium ion, ammonium ion and the like are preferable.

Examples of the ion solid containing alkali metal ions include lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithiumbispentafluoroethylsulfonylimide, lithiumbisheptafluoropropylsulfonylimide, lithiumbisnonanfluorobutylsulfonylimide, and sodium bis. Fluorosulfonylimide, sodium bistrifluoromethylsulfonylimide, sodium bispentafluoroethylsulfonylimide, sodium bisheptafluoropropylsulfonylimide, sodium bisnonanfluorobutylsulfonylimide, potassium bisfluorosulfonylimide, potassium bistrifluoromethylsulfonylimide, potassium bis Examples thereof include pentafluoroethyl sulfonylimide, potassium bisheptafluoropropylsulfonylimide, and potassium bisnonanfluorobutylsulfonylimide.

Examples of the ion solid containing phosphonium ions include tetrabutylphosphonium bisfluorosulfonylimide, tetrabutylphosphonium bistrifluoromethylsulfonylimide, tetrabutylphosphonium bispentafluoroethylsulfonylimide, tetrabutylphosphonium bisheptafluoropropylsulfonylimide, and tetrabutylphosphonium. Bisnonanfluorobutylsulfonylimide, tributylhexadecylphosphonium bisfluorosulfonylimide, tributylhexadecylphosphonium bistrifluoromethylsulfonylimide, tributylhexadecylphosphonium bispentafluoroethylsulfonylimide, tributylhexadecylphosphonium bisheptafluoropropylsulfonylimide, tributylhexa Decylphosphonium bisnonan fluorobutylsulfonylimide, tetraoctylphosphonium bisfluorosulfonylimide, tetraoctylphosphonium bistrifluoromethylsulfonylimide, tetraoctylphosphonium bispentafluoroethylsulfonylimide, tetraoctylphosphonium bisheptafluoropropylsulfonylimide, and tetraoctylphosphonium Examples thereof include bisnonanfluorobutylsulfonylimide.

Examples of the ion solid containing pyridinium ion include 1-hexadecyl-4-methylpyridinium bisfluorosulfonylimide, 1-hexadecyl-4-methylpyridinium bistrifluoromethylsulfonylimide, and 1-hexadecyl-4-methylpyridinium bispentafluoroethylsulfonyl. Examples thereof include imide, 1-hexadecyl-4-methylpyridinium bisheptafluoropropylsulfonylimide, 1-hexadecyl-4-methylpyridinium bisnonanfluorobutylsulfonylimide and the like.

Examples of the ion solid containing ammonium ion include lauryltrimethylammonium chloride, tributylmethylbistrifluoromethylsulfonylimide, tributylmethylbispentafluoroethylsulfonylimide, tributylmethylbisheptafluoropropylsulfonylimide, and tributylmethylmubisnonanfluorobutylsulfonylimide. , Octiltributylbistrifluoromethylsulfonylimide, octyltributylbispentafluoroethylsulfonylimide, octyltributylbisheptafluoropropylsulfonylimide, octtilthlibutylmubisnonanfluorobutylsulfonylimide, tetrabutylbisfluorosulfonylimide, tetrabutylbistrifluoromethylsulfonyl Examples thereof include imide, tetrabutylbispentafluoroethylsulfonylimide, tetrabutylbisheptafluoropropylsulfonylimide, and tetrabutylmubisnonanfluorobutylsulfonylimide.

In addition, known ionic solids whose cations are pyrrolidinium ion, imidazolium ion, sulfonium ion and the like can be appropriately used.

Examples of the surfactant include nonionic surfactants and anionic surfactants, and both types are classified into low molecular weight surfactants and high molecular weight surfactants.

Examples of the nonionic low molecular weight surfactant include glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amine fatty acid ester, fatty acid diethanolamide and the like. Be done.
Examples of the anionic low molecular weight surfactant include alkyl sulfonates, alkylbenzene sulfonates, alkyl phosphates and the like.
Examples of the amphoteric small molecule surfactant include alkyl betaine and alkyl imidazolium betaine.

Examples of the nonionic polymer surfactant include a polyether ester amide type, an ethylene oxide-epichlorohydrin type, and a polyether ester type.
Examples of the anionic polymer surfactant include polystyrene sulfonic acid type.
Examples of the amphoteric polymer surfactant include amino acid type amphoteric surfactants such as higher alkylaminopropionate, higher alkyldimethylbetaine, and betaine type amphoteric surfactants such as higher alkyldihydroxyethylbetaine.

The amount of the antistatic agent (AS) added is preferably 0.01 to 10 parts by mass, and 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 may contain a leveling agent, if necessary. 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-based leveling agent, a silicone-based leveling agent, and the like, and an acrylic-based leveling agent and the like are preferable from the viewpoint of suppressing adhesion contamination after re-peeling of the pressure-sensitive adhesive sheet.

The amount of the leveling agent added is not particularly limited, and is preferable with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (UPH) from the viewpoint of suppressing adherent contamination after re-peeling the pressure-sensitive adhesive sheet and improving the leveling property of the pressure-sensitive adhesive layer. It 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 may contain other optional components, if 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, conductivity. Examples thereof include agents, silane coupling agents, lubricants, corrosion inhibitors, heat-resistant stabilizers, weather-resistant stabilizers, polymerization inhibitors, defoaming agents and the like.
When the pressure-sensitive adhesive of the present invention contains a catalyst, it is preferable to add a known catalytic action inhibitor such as acetylacetone for the purpose of improving the pot life of the pressure-sensitive adhesive.

(Mixing ratio)
The pressure-sensitive adhesive of the present invention contains one or more hydroxyl-terminated urethane prepolymers (UPH) having a specific degree of branching α and one or more polyfunctional isocyanate compounds (I) as essential components, and further contains, if necessary. Contains one or more optional ingredients. These compounding ratios are not particularly limited, but preferable compounding ratios are as follows.
The amount of one or more polyfunctional isocyanate compounds (I) with respect to 100 parts by mass of one or more hydroxyl-terminated urethane prepolymers (UPH) is preferably 1 to 30 parts by mass, more preferably 5 to 25 parts by mass, and particularly preferably. Is 8 to 20 parts by mass. When the amount of one or more polyfunctional isocyanate compounds (I) is 1 part by mass or more, the cohesive force of the adhesive layer is good, and when it is 30 parts by mass or less, the pot life is good.

(Manufacturing method of adhesive)
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited.
For one or more hydroxyl-terminated urethane prepolymers (UPH) (which may be in the form of a solution containing a solvent) synthesized by the above method, one or more polyfunctional isocyanate compounds (I) and, if necessary The pressure-sensitive adhesive of the present invention can be produced by adding and mixing one or more other arbitrary components.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base material sheet and a pressure-sensitive adhesive layer made of the cured product of the above-mentioned pressure-sensitive adhesive of the present invention. The adhesive layer can be formed on one side or both sides of the base sheet. If necessary, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is peeled off before the adhesive sheet is attached to the adherend.

FIG. 1 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 is an adhesive sheet, reference numeral 11 is a base material 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 an pressure-sensitive adhesive layer is formed on one side of a base material sheet.
FIG. 2 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention. 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 pressure-sensitive adhesive sheet 20 is a double-sided pressure-sensitive adhesive sheet in which pressure-sensitive adhesive layers are formed on both sides of the base material sheet.

The base material sheet is not particularly limited, and examples thereof include resin sheets, paper, and metal foils. 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. If necessary, the surface of the base sheet on the side where the adhesive layer is formed may be subjected to an easy-adhesion treatment such as a corona discharge treatment and an anchor coating agent application.

The constituent resin of the resin sheet is not particularly limited, and is an ester resin such as polyethylene terephthalate (PET); an olefin resin such as polyethylene (PE) and polypropylene (PP); a vinyl resin such as polyvinyl chloride; a nylon 66 and the like. Amid-based resins; urethane-based resins (including foams); combinations thereof and the like can be mentioned.
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 the 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 applied to the surface of a base sheet such as a resin sheet or paper can be used.

[Manufacturing method of adhesive sheet]
The pressure-sensitive adhesive sheet can be manufactured by a known method.
First, the pressure-sensitive adhesive of the present invention is applied to the surface of the base material sheet to form a coating layer made of the pressure-sensitive adhesive of the present invention. As the coating method, a known method can be applied, 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 application, 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.
As described above, the single-sided adhesive sheet can be manufactured.
By performing the above operation on both sides, a double-sided adhesive sheet can be manufactured.

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 made of the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to form the present invention. A pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive may be formed, and a base material sheet may be laminated on the exposed surface of the pressure-sensitive adhesive layer.

The method for producing the pressure-sensitive adhesive sheet is preferably a coating step of applying a pressure-sensitive adhesive on the base material sheet and heating to heat-dry the formed coating layer to form a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive. It includes a step, a winding step of winding the obtained adhesive sheet around a winding core to form an adhesive sheet roll, and a curing step of curing the adhesive sheet roll.

As described above, according to the present invention, the adhesive layer has good initial curability, suppresses an increase in adhesive strength even when exposed to a thermal environment, particularly a moist thermal environment, and has good removability. It is possible to provide a pressure-sensitive adhesive capable of forming the above-mentioned material, and a pressure-sensitive adhesive sheet using the same.
According to the first embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a moist thermal environment are good, and further, the base material is formed. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good adhesion, scratch resistance, and curved surface adhesion, and a pressure-sensitive adhesive sheet using the same.
According to the second embodiment of the present invention, the initial curability and the removability (effect of suppressing the increase in adhesive strength) when exposed to a thermal environment, particularly a moist thermal environment are good, and further, folding resistance is good. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good properties, cutability, and heat resistance, and a pressure-sensitive adhesive sheet using the same.

[Use]
The pressure-sensitive adhesive sheet of the present invention can be used in the form of tapes, labels, stickers, double-sided tapes and the like. The adhesive sheet of the present invention is suitably used as a surface protective sheet, a cosmetic sheet, a non-slip sheet and the like.
Unless otherwise specified in the present specification, "sheet" shall include "film" and "tape".
Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (OELDs), as well as touch panel displays that combine such flat panel displays and touch panels, include televisions (TVs), personal computers (PCs), mobile phones, and the like. It is also widely used in electronic devices such as mobile information terminals.
The adhesive sheet of the present invention includes a flat panel display and a touch panel display (collectively referred to as "displays"), and substrates manufactured or used in these manufacturing processes (glass substrate and ITO on a glass substrate). (ITO / glass substrate or the like on which a (indium tin oxide) film is formed) and a surface protective sheet for optical members and the like are suitably used.

Hereinafter, synthetic examples, examples according to the present invention, and comparative examples will be described. In the following description, unless otherwise specified, "parts" means parts by mass, "%" means mass%, and "RH" means relative humidity. Unless otherwise specified, the unit of compounding amount in the table is "part by mass". Unless otherwise specified, the blending amount of the components other than the solvent is a non-volatile content conversion value.

[Evaluation items and evaluation methods for materials or hydroxyl group-terminated urethane prepolymers]
The evaluation items and evaluation methods for the material or the hydroxyl group-terminated urethane prepolymer are as follows.
(Mw, Mn)
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method. The measurement conditions are as follows. Both Mw and Mn are polystyrene-equivalent values.
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: SHODEX L
Connect 3 F-804 (manufactured by Showa Denko KK) in series,
Detector: Differential refractometer,
Solvent: Tetrahydrofuran (THF),
Flow rate: 1 mL / min,
Solvent temperature: 40 ° C,
Sample concentration: 0.2%,
Sample injection amount: 200 μL.

(Branch degree α)
The degree of branching α was measured using a device (GPC-MALS-VISCO) in which a gel permeation chromatograph (GPC) was combined with a multi-angle light scattering detector (MALS) and a viscosity detector (VISCO).

(Viscosity of hydroxyl-terminated urethane prepolymer solution)
The viscosity of the hydroxyl group-terminated urethane prepolymer solution at 25 ° C. was measured immediately after preparation by placing it in a glass bottle with a lid and immersing it in a constant temperature water bath at 25 ° C., and then measuring the viscosity 1 hour later. The viscosity was measured using a B-type viscometer (“TVB10 type viscometer” manufactured by Toki Sangyo Co., Ltd.).

(Non-volatile content)
The non-volatile content of the solution of the hydroxyl group-terminated urethane prepolymer was determined from the mass change after drying after heating and drying about 1 g of the sample at 120 ° C. for 20 minutes.

[Example of polyol synthesis]
(Synthesis Example Z-1)
An autoclave equipped with a stirrer and a temperature control device was charged with 100.0 parts of butylethylpropanediol (BEPD) as the first component and 4.0 parts of potassium hydroxide, and then heated to 100 ° C. for stirring. Below, 150.0 parts of propylene oxide (PO) as the second component was continuously added.
To the obtained reaction product, 40.0 parts of water and 40.0 parts of an alkaline adsorbent "Kyoward 600" (manufactured by Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred and mixed under 90 ° C. conditions for 1 hour. .. Then, the added alkaline adsorbent was removed using a filter covered with filter paper. The reaction product that had passed through the filter paper was dehydrated under the conditions of 130 ° C. and a pressure of 2.7 kPa.
As described above, a polyether polyol (HX-1) having a number average molecular weight (Mn) of 400, an average functional group series of secondary, and a branching degree α of 0.45 was obtained. The raw material composition and the types and characteristics of the obtained polyols are shown in Table 1-1 and Table 1-2.

(Synthesis Examples Z-3, Z-11)
A polyol was obtained in the same manner as in Synthesis Example Z-1 except that the types and amounts of the first component and the second component were changed. The raw material composition and the types and characteristics of the obtained polyols are shown in Table 1-1 and Table 1-2.

(Synthesis Example Z-2)
In an autoclave equipped with a stirrer and a temperature control device, 100 parts of terephthalic acid (TPA) as the first component, 27 parts of trimethylolpropane (TMP) as the second component, and 1,9- as the third component. 74 parts of nonanediol (ND) was charged. The esterification reaction was carried out by heating to 200 ° C. under a normal pressure nitrogen atmosphere and distilling the generated water out of the system. When the amount of distillate of the produced water decreased, 0.01 part of terroraisopropyl titanate was added, and the reaction was continued while reducing the pressure with a vacuum pump. A polyester polyol (HX-2) having a branching degree α of 0.35 was obtained.

(Synthesis Example Z-7, Z-10, Z-16)
A polyol was obtained in the same manner as in Synthesis Example Z-2 except that the types and amounts of the first component, the second component, and the third component were changed. The raw material composition and the types and characteristics of the obtained polyols are shown in Table 1-1 and Table 1-2.

(Synthesis Example Z-4)
An autoclave equipped with a stirrer and a temperature control device is charged with 100.0 parts of glycerin and 4.0 parts of potassium hydroxide as the first component, then heated to 100 ° C. and used as the second component under stirring. 334 parts of 1,2-butylene oxide (1,2-BO) was continuously added.
To the obtained reaction product, 40.0 parts of water and 40.0 parts of an alkaline adsorbent "Kyoward 600" (manufactured by Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred and mixed under 90 ° C. conditions for 1 hour. .. Then, the added alkaline adsorbent was removed using a filter covered with filter paper. The reaction product that had passed through the filter paper was dehydrated under the conditions of 130 ° C. and a pressure of 2.7 kPa.
After charging the above reaction product into an autoclave equipped with a stirrer and a temperature control device and further charging 0.10 part of a zinc hexacyanocobalate catalyst, the temperature inside the reactor was raised to 130 ° C. and the mixture was stirred. 282 parts of 1,2-butylene oxide (1,2-BO) as the third component (10% by mass of the total amount used) was added.
After reacting for 2 hours and activating the catalyst, 2538 parts (90% by mass of the total amount used) of 1,2-butylene oxide (1,2-BO) as the third component was continuously added under the condition of 100 ° C. The mixture was mixed and stirred at 95 ° C. until the pressure became constant. The resulting mixture was vacuum stripped at 100 ° C. for 0.5 hours to remove the unreacted third component from the reactor.
As described above, a polyether polyol (HX-S-2) having a number average molecular weight (Mn) of 3000, an average functional group series of secondary, and a branching degree α of 0.05 was obtained. The raw material composition and the characteristics of the obtained polyol are shown in Table 1-1 and Table 1-2.

(Synthesis Example Z-5, Z-6, Z-9, Z-12 to Z-15)
A polyol was obtained in the same manner as in Synthesis Example Z-4 except that the types and amounts of the first component, the second component, and the third component were changed. The raw material composition and the types and characteristics of the obtained polyols are shown in Table 1-1 and Table 1-2.

(Synthesis Example Z-8)
1854 g of polycarbonate diol (trade name CD220, molecular weight 2011, hydroxyl value 55.8), trimethylolpropane 21 g, in a round bottom flask equipped with a stirrer, a thermometer, a nitrogen introduction tube, and a condenser. 126 g of pentaerythritol and 0.08 g of tetrabutyl titanate as a catalyst were charged. The mixture was heated under normal pressure with stirring. The reaction temperature was gradually increased, and after reaching 220 ° C., this temperature was maintained for 8 hours to carry out the reaction.
Sampling is performed at any time during the reaction, and the residual diol component (here, 1,6-hexanediol) and triol component (here, trimethylolpropane) are quantified by gas chromatography analysis, and the transesterification reaction is in an equilibrium state. After confirming that it became, the reaction was terminated.
As described above, a polycarbonate polyol (HX-S-6) having a number average molecular weight (Mn) of 1000, an average functional group series of tertiary, and a branching degree α of 0.05 was obtained. The raw material composition and the types and characteristics of the obtained polyols are shown in Table 1-1 and Table 1-2.

Each abbreviation in Table 1-1 and Table 1-2 indicates the following compounds.
BEPD: Butyl Ethyl Propanediol,
TPA: terephthalic acid,
AA: Adipic acid,
PG: Propylene glycol,
IPA: Isophthalic acid,
PO: Propylene oxide,
TMP: Trimethylolpropane,
1,2-BO: 1,2-butylene oxide,
EO: Ethylene oxide,
THF: tetrahydrofuran,
PD-9: 2,4-diethyl-1,5-pentanediol,
ND: 1,9-nonanediol,
MPD: 2-methylpentane-2,4-diol,
CD220: Polycarbonate diol (manufactured by Daicel Chemical Industry Co., Ltd .: trade name CD220, molecular weight 2011, hydroxyl value 55.8),
PET: Pentaerythritol.

[material]
The materials used are as follows.
The types of active hydrogen group-containing compounds (HX) and (HY) used, the number of functional groups, Mn, the average series of functional groups, and the degree of branching α are shown in Table 1-2. The type of polyisocyanate (N) used, the number of functional groups, and Mn are shown in Table 1-2.

<Active hydrogen group-containing compound (HX)>
(HX-1): Polyether polyol.
(HX-2): Polyester polyol.
(HX-S-1): Polycaprolactone polyol.
(HX-S-2): Polyether polyol.
(HX-S-3): Polyether polyol.
(HX-S-4): Polyether polyol.
(HX-S-5): Polyester polyol.
(HX-S-6): Polycarbonate polyol.
(HX-S-7): Polyether polyol, "DK polyol G480" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.
(HX-S-8): Polyether polyol, "ADEKA polyether AM-302" manufactured by ADEKA.

<Active hydrogen group-containing compound (HY)>
(HY-1): Polyether polyol.
(HY-2): Polyester polyol.
(HY-L-1): Polyether polyol.
(HY-L-2): Polyether polyol.
(HY-L-3): Polyether polyol.
(HY-L-4): Polyether polyol.
(HY-L-5): Polyether polyol.
(HY-L-6): Polyester polyol.
(HY-L-7): Polyether polyol, "Polyhardner D-100A" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.
(HY-L-8): Polyester polyol, "Kuraray Polyol P-1010" manufactured by Kuraray Co., Ltd.
(HY-L-9): Polyether polyol, "Polyhardner D-40" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.

<Polyisocyanate (N)>
(N-1): HDI, hexamethylene diisocyanate, manufactured by Sumika Covestro Urethane, Death Module H.
(N-2): IPDI, isophorone diisocyanate, manufactured by Sumika Covestro Urethane, Death Module I.
(N-3): TDI, tolylene diisocyanate (mixture of 2,4-tolylene diisocyanate (80% by mass) and 2,6-tolylene diisocyanate (20% by mass)), Coronate T-80 manufactured by Tosoh Corporation. ..
(N-4): HDI Nurate, Sumijour N-3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate (HDI) / isocyanurate.

<Polyfunctional isocyanate compound (I)>
(I-1) HDI Adduct, Coronate HL, manufactured by Tosoh Corporation, hexamethylene diisocyanate (HDI) / trimethylolpropane (TMP) adduct.
(I-2) HDI Nurate, Sumijour N-3300, manufactured by Sumika Bayer Urethane, hexamethylene diisocyanate (HDI) / isocyanurate.

<Antioxidant (O)>
(O-1): IRGANOX 1010, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], phenolic antioxidant, manufactured by BASF.

<Plasticizer (P)>
(P-1): ADEKA SIZER RS700, polyether ester-based plasticizer, manufactured by ADEKA.
(P-2): Exepearl MOL, methyl oleate, manufactured by Kao Corporation.

<Antistatic agent (AS)>
(AS-1): Ionic liquid, tri-n-butylmethylammonium / bistrifluoromethanesulfonimide.

[Synthesis example of a solution of hydroxyl group-terminated urethane prepolymer (UPH)]
(Synthesis Example 1) One-stage dropping method (Method 1)
In a four-necked flask equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, a thermometer, and a dropping funnel, 80.0 parts by mass of the active hydrogen group-containing compound (HX-S-1) and the active hydrogen group-containing compound ( HY-L-5) 20.0 parts by mass, 42.8 parts by mass of toluene, 0.020 parts by mass of dioctyl tin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate were charged and mixed as catalysts. Then, the content liquid was gradually heated to 80 ° C.
25.0 parts by mass of polyisocyanate (N-1) and 24.5 parts by mass of toluene were charged and mixed in the dropping funnel, and this mixed solution was dropped into a 4-necked flask over 1 hour. After the completion of the dropping, the reaction was carried out for 1 hour.
The ratio of the number of moles of isocyanate groups (NCO / H ratio) of the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups of all the active hydrogen group-containing compounds (H) used in the reaction is. It was 0.78.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40 ° C. to terminate the reaction. Finally, 0.56 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl group-terminated urethane prepolymer (UPH-1) having a non-volatile content of 65% and a viscosity of 3200 cps was obtained. Table 2-1 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α. In each example of Table 2-1 and Table 2-2, Table 3-1 and Table 3-2, and Table 4, the conditions not shown in the table were set as common conditions.

(Synthesis Examples 2 to 14, 19 to 33) One-stage dropping method (Method 1)
In Synthesis Examples 2 to 14 and 19 to 33, the same as in Synthesis Example 1 is colorless except that the type of the active hydrogen group-containing compound (H), the type of the polyisocyanate (N), and the compounding ratio thereof are changed. A transparent solution of hydroxyl group-terminated urethane prepolymer (UPH-2) to (UPH-14) and (UPH-19) to (UPH-33) was obtained. In each synthesis example, the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α are shown in Tables 2-1 and 2-2, Table 3-1 and Tables. Shown in 3-2.

(Synthesis example 15) Batch preparation method (method 2)
In a 4-necked flask equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, a thermometer, and a dropping funnel, 32.0 parts by mass of the active hydrogen group-containing compound (HX-S-7) and the active hydrogen group-containing compound ( HY-L-7) 68.0 parts by mass, polyisocyanate (N-1) 26.0 parts by mass, 67.8 parts by mass of toluene, and 0.020 parts by mass of dioctyltin dilaurate as a catalyst were charged and mixed. .. Then, the content was heated to 80 ° C. and reacted for 3 hours.
The ratio of the number of moles of isocyanate groups (NCO / H ratio) of the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups of all the active hydrogen group-containing compounds (H) used in the reaction is. It was 0.75.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40 ° C. to terminate the reaction. Finally, 0.56 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-15) having a non-volatile content of 65% and a viscosity of 1800 cps was obtained. Table 2-2 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α.

(Synthesis Examples 16 and 34) Batch Preparation Method (Method 2)
In Synthesis Examples 16 and 34, the colorless and transparent hydroxyl group ends are the same as in Synthesis Example 15 except that the type of the active hydrogen group-containing compound (H), the type of the polyisocyanate (N), and the compounding ratio thereof are changed. A solution of urethane prepolymer (UPH-16) and (UPH-34) was obtained. In each synthesis example, the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α are shown in Tables 2-2 and 3-2.

(Synthesis Examples 41 and 42) Batch preparation method (Method 2)
In Synthesis Examples 41 and 42, the same as in Synthesis Example 14 except that the type of the active hydrogen group-containing compound (H), the type of the polyisocyanate (N), and the compounding ratio thereof were changed, was colorless and transparent for comparison. A solution of the hydroxyl group-terminated urethane prepolymer (UPC-41) and (UPC-42) was obtained. In each synthetic example, the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α are shown in Table 4.

(Synthesis Example 17) Two-stage reaction method (Method 3)
80.0 parts by mass of active hydrogen group-containing compound (HX-S-2) and 50.5 parts by mass of toluene in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel. And 0.020 parts by mass of dioctyltin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate were charged and mixed as catalysts. Then, the content liquid was gradually heated to 80 ° C.
4.0 parts by mass of polyisocyanate (N-1) and 4.0 parts by mass of toluene were charged and mixed in the dropping funnel, and this mixed solution was dropped into a 4-necked flask over 1 hour. After the completion of the dropping, the reaction was carried out for 1 hour.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 60 ° C. or lower. After adding 20.0 parts by mass of the active hydrogen group-containing compound (HY-L-6) to this content liquid and mixing, the content liquid was gradually heated to 80 ° C.
1.5 parts by mass of polyisocyanate (N-1) and 3.0 parts by mass of toluene were charged in the dropping funnel and mixed, and this mixed solution was dropped into a 4-necked flask over 1 hour. After the completion of the dropping, the reaction was carried out for 1 hour.
The ratio of the number of moles of isocyanate groups (NCO / H ratio) of the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups of all the active hydrogen group-containing compounds (H) used in the reaction is. It was 0.65.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40 ° C. to terminate the reaction. Finally, 0.46 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-17) having a non-volatile content of 65% and a viscosity of 7,000 cps was obtained. Table 2-2 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α.

(Synthesis Example 35) Two-stage reaction method (Method 3)
In Synthesis Example 35, the colorless and transparent hydroxyl group-terminated urethane prepolymer is the same as in Synthesis Example 17 except that the type of the active hydrogen group-containing compound (H), the type of the polyisocyanate (N), and the compounding ratio thereof are changed. A solution of the polymer (UPH-35) was obtained. Table 3-2 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α.

(Synthesis Example 18) Two-stage reaction method (Method 4)
20.0 parts by mass of active hydrogen group-containing compound (HY-L-6) and 50.5 parts by mass of toluene in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel. And 0.020 parts by mass of dioctyltin dilaurate and 0.008 parts by mass of tin 2-ethylhexanoate were charged and mixed as catalysts. Then, the content liquid was gradually heated to 80 ° C.
1.5 parts by mass of polyisocyanate (N-1) and 3.0 parts by mass of toluene were charged in the dropping funnel and mixed, and this mixed solution was dropped into a 4-necked flask over 1 hour. After the completion of the dropping, the reaction was carried out for 1 hour.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 60 ° C. or lower. 80.0 parts by mass of the active hydrogen group-containing compound (HX-S-2) was added to this content liquid and mixed, and the content liquid was gradually heated to 80 ° C.
4.0 parts by mass of polyisocyanate (N-1) and 4.0 parts by mass of toluene were charged and mixed in the dropping funnel, and this mixed solution was dropped into a 4-necked flask over 1 hour. After the completion of the dropping, the reaction was carried out for 1 hour.
The ratio of the number of moles of isocyanate groups (NCO / H ratio) of the polyisocyanate (N) used in the reaction to the total number of moles of active hydrogen groups of all the active hydrogen group-containing compounds (H) used in the reaction is. It was 0.65.
After confirming the disappearance of the residual isocyanate group by infrared spectroscopic analysis (IR analysis), the content liquid was cooled to 40 ° C. to terminate the reaction. Finally, 0.46 parts by mass of acetylacetone was added.
As described above, a solution of a colorless and transparent hydroxyl-terminated urethane prepolymer (UPH-18) having a non-volatile content of 65% and a viscosity of 2800 cps was obtained. Table 2-2 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α.

(Synthesis Example 36) Two-stage reaction method (Method 4)
In Synthesis Example 36, the colorless and transparent hydroxyl group-terminated urethane prepolymer is the same as in Synthesis Example 18 except that the type of the active hydrogen group-containing compound (H), the type of the polyisocyanate (N), and the compounding ratio thereof are changed. A solution of the polymer (UPH-36) was obtained. Table 3-2 shows the main compounding composition, NCO / H ratio, and Mw and Mn of the obtained hydroxyl group-terminated urethane prepolymer and the degree of branching α.

[Manufacturing of adhesives and adhesive sheets]
(Example 1)
100 parts by mass of the solution of the hydroxyl group-terminated urethane prepolymer (UPH-1) obtained in Synthesis Example 1, 15 parts by mass of the polyfunctional isocyanate compound (I-1), and 1 part by mass of the antioxidant (O-1). , 15 parts by mass of the plasticizing agent (P-1) and 100 parts by mass of ethyl acetate as a solvent were mixed and stirred with a disper to obtain a urethane-based pressure-sensitive adhesive. The amount of each material other than the solvent used indicates a non-volatile content conversion value (the same applies to other examples and comparative examples). The main compounding compositions are shown in Table 5.

As a base material sheet, a 50 μm thick polyethylene terephthalate film (PET film, Lumirer T-60: manufactured by Toray Industries, Inc.) was prepared. The obtained pressure-sensitive adhesive was applied to one side of this base material sheet so that the thickness of the pressure-sensitive adhesive layer after drying was 12 μm, and dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer. A release sheet having a thickness of 38 μm (Super Stick SP-PET38: manufactured by Lintec Corporation) was attached onto this adhesive layer to obtain an adhesive sheet. After curing at 23 ° C.-50% RH for 1 week, various evaluations were performed.

(Examples 2 to 57, Comparative Examples 1 and 2)
In each of Examples 2 to 57 and Comparative Examples 1 and 2, the urethane-based pressure-sensitive adhesive and the urethane-based pressure-sensitive adhesive were the same as in Example 1 except that the composition of the pressure-sensitive adhesive was changed as shown in Tables 5 and 7. An adhesive sheet was manufactured using the above. In each of the examples in Tables 5 and 7, the conditions not shown in the table were set as common conditions.

[Evaluation items and evaluation methods for adhesive sheets]
The evaluation items and evaluation methods of the adhesive sheet are as follows.

(Adhesion to base material)
The adhesive layer of the obtained adhesive sheet was half-cut 11 times at 1 mm intervals in two linear directions orthogonal to each other to form 100 cells of 1 mm square. After rubbing the entire 100 squares with a finger 20 times, the number of squares remaining on the base sheet was visually counted. The evaluation criteria are as follows.
◎: The number of remaining squares is 71 to 100, which is excellent.
◯: The number of remaining squares is 51 to 70, which is good.
Δ: The number of remaining squares is 21 to 50, which is practical.
×: The number of remaining cells is 0 to 20, which is not practical.

(Initial curability)
The release sheet was peeled off from the obtained adhesive sheet. The surface of the exposed adhesive layer was rubbed with a fingertip, and the presence or absence of adhesion of the components of the adhesive layer to the fingertip and the presence or absence of rubbing marks on the surface of the adhesive layer were visually observed. The evaluation criteria are as follows.
⊚: Excellent, with no adhesive layer components adhering to the fingertips and no rubbing marks left on the surface of the adhesive layer.
◯: The component of the adhesive layer does not adhere to the fingertips, but a slight rubbing mark remains on the surface of the adhesive layer, which is good.
Δ: Some components of the adhesive layer adhere to the fingertips, giving a feeling of tackiness, and a slight rubbing mark remains on the surface of the adhesive layer, which is practical.
X: The components of the adhesive layer are remarkably adhered to the fingertips, giving a sticky feeling, and rubbing marks remain on the surface of the adhesive layer, which is not practical.

(Scratch resistance)
The release sheet was peeled off from the obtained adhesive sheet. The tip (pen tip) of a POM pen (pen tip diameter 0.8 mm) tilted at an angle of 45 ° with respect to the surface of the exposed adhesive layer was brought into contact with the surface of the adhesive layer. While maintaining this state, the pen tip was moved horizontally by about 10 cm so as to draw a straight line. The same operation was performed at a total of 10 locations by changing the positions. The presence or absence of scratches was visually observed at each location, and the number of locations where scratches were formed was determined. Visual inspection was performed under fluorescent lighting. The evaluation criteria are as follows.
◎: Excellent with no scratches.
◯: Good, with scratches in 1 or 2 places.
Δ: There are scratches in 3 to 5 places, practically possible.
×: There are scratches in 6 or more places, which is not practical.

(Adhesion to curved surface)
A test piece having a width of 25 mm and a length of 40 mm was cut out from the obtained adhesive sheet. Next, the release sheet was peeled off from the test piece in an atmosphere of 23 ° C.-50% RH, and the exposed adhesive layer was attached along the peripheral surface of a polypropylene cylinder (diameter 30 mmφ, height 300 mm). rice field. At this time, the width direction of the test piece and the height direction of the cylinder were matched. After allowing this sample to stand in an atmosphere of 23 ° C.-50% RH for 3 days, the degree of adhesion of the test piece to the cylinder was visually observed. The evaluation criteria are as follows.
◯: Good, with no floating at the end of the test piece.
Δ: There is a float at the end of the test piece, and the width of the peeled part is 1 mm or more and less than 3 mm, which is practical.
X: There is a float at the end of the test piece, the width of the peeled part is 3 mm or more, and it is not practical.

(Removability (60 ° C-90% RH, 24 hours))
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet. Then, in an atmosphere of 23 ° C.-50% RH, the release sheet was peeled off from the test piece, the exposed adhesive layer was attached to a caustic soda glass plate, and a 2 kg roll was reciprocated once from the top of the test piece for pressure bonding. Then, it was left for 24 hours in an atmosphere of 60 ° C.-90% RH, and air-cooled for 30 minutes in an atmosphere of 23 ° C.-50% RH. Then, according to JIS Z 0237, the adhesive strength was measured using a tensile tester (Tencilon: manufactured by Orientec) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °. The lower the adhesive strength, the easier it is to peel off again. The evaluation criteria are as follows.
⊚: Less than 50 mN / 25 mm, excellent.
◯: 50 mN / 25 mm or more and less than 100 mN / 25 mm, good.
Δ: 100 mN / 25 mm or more, 300 mN / 25 mm, practically possible.
×: Over 300 mN / 25 mm, not practical.

(Fold resistance)
A test piece having a width of 25 mm and a length of 40 mm was cut out from the obtained adhesive sheet. Then, in an atmosphere of 60 ° C., the release sheet was peeled off from the test piece, about half of the exposed adhesive layer in the length direction was attached to a caustic soda glass plate having a thickness of 10 mm, and the rest was folded back in the 180 ° direction. I pasted it. It was left for 3 days in an atmosphere of 60 ° C. After that, the degree of adhesion to the caustic soda glass plate was visually observed at the bent portion and the end portion of the portion to which the test piece was attached. The evaluation criteria are as follows.
◎: Excellent with no floating at the bent part and the end.
◯: There is a float at the bent part and / or the end, the width of the peeled part is less than 1 mm, good Δ: There is a float at the bent part and / or the end, the width of the peeled part is 1 mm or more and less than 3 mm, practical use. Yes.
X: There is a float at the bent part and / or the end part, the width of the peeled part is 3 mm or more, and it is not practical.

(Cutability)
A 100 mm square test piece was cut out from the obtained adhesive sheet. As a punching machine, SA1008 small punching machine type III (manufactured by Tester Sangyo) was prepared. Cutability was evaluated by continuously punching 50 shots with a circular Thomson blade having a diameter of 10 mm. The evaluation criteria are as follows.
◎: Excellent that the adhesive component does not adhere to the blade and the release sheet can be removed cleanly from the punched circular adhesive sheet with a light force.
◯: The adhesive component slightly adheres to the blade, but the release sheet can be removed cleanly from the punched circular adhesive sheet with a light force, which is good.
Δ: A little adhesive component adheres to the blade, or there is a little resistance when peeling the release sheet from the punched circular adhesive sheet, which is practically possible.
X: The adhesive component adheres remarkably to the blade, or the resistance when peeling the release sheet from the punched circular adhesive sheet is large, which is not practical.

(Heat resistance (150 ° C, 1 hour))
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet. Then, in an atmosphere of 23 ° C.-50% RH, the release sheet was peeled off from the test piece, the exposed adhesive layer was attached to a caustic soda glass plate, and a 2 kg roll was reciprocated once from the top of the test piece for pressure bonding. Then, it was left in an atmosphere of 150 ° C. for 1 hour, and air-cooled in an atmosphere of 23 ° C.-50% RH for 30 minutes. Then, according to JIS Z 0237, the adhesive strength was measured using a tensile tester (Tencilon: manufactured by Orientec) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °. The lower the adhesive strength, the easier it is to peel off again. The evaluation criteria are as follows.
⊚: Less than 500 mN / 25 mm, excellent.
◯: 500 mN / 25 mm or more and less than 1000 mN / 25 mm, good.
Δ: 1000 mN / 25 mm or more 3000 mN / 25 mm, practically possible.
×: Over 3000 mN / 25 mm, not practical.

[Evaluation results]
The evaluation results are shown in Tables 6 and 8.
In Synthesis Examples 1 to 36, one species containing an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less and / or an active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5. Using the above active hydrogen group-containing compound (H) and polyisocyanate (N), hydroxyl group-terminated urethane prepolymers (UPH-1) to (UPH-36) having a branching degree α of 0.2 to 0.8. ) Was obtained.
In Examples 1 to 57 using hydroxyl group-terminated urethane prepolymers (UPH-1) to (UPH-36) having a degree of branching α of 0.2 to 0.8, the obtained pressure-sensitive adhesive sheets had initial curability and The evaluation result of the removability (60 ° C.-90% RH) was good. The evaluation results were also good for other evaluation items.

In Synthesis Examples 1 to 13, 16 and 17, one or more active hydrogen group-containing compounds (H) contain 50% by mass or more of the active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less. The hydroxyl group-terminated urethane prepolymer (UPH) had a branching degree α of 0.2 to 0.6. The pressure-sensitive adhesive sheets obtained in Examples 1 to 22, 25, and 26 using the hydroxyl group-terminated urethane prepolymers (UPH) obtained in these synthetic examples are exposed to the initial curability and the thermal environment, particularly the moist heat environment. The re-peelability (effect of suppressing the increase in adhesive strength) was good, and the substrate adhesion, scratch resistance, and curved surface adhesion were good.

In Synthesis Examples 19 to 29, 31, 33, 36, the active hydrogen group-containing compound (H) of one or more kinds contains 50% by mass or more of the active hydrogen group-containing compound (HY) having a branching degree α of more than 0.5. The hydroxyl group-terminated urethane prepolymer (UPH) contained, and the degree of branching α was more than 0.6 and 0.8 or less. The adhesive sheets obtained in Examples 28 to 46, 48, 50, and 53 using the hydroxyl group-terminated urethane prepolymers (UPH) obtained in these synthetic examples have initial curability and are suitable for a thermal environment, particularly a moist thermal environment. The re-peelability (effect of suppressing the increase in adhesive strength) when exposed was good, and the folding resistance, cutting resistance, and heat resistance were also good.

In Synthesis Example 41, a comparative hydroxyl group terminal having a branching degree α of less than 0.2 using an active hydrogen group-containing compound (HX) having a branching degree α of 0.5 or less and a polyisocyanate (N). Urethane prepolymer (UPC-1) was obtained.
In Synthesis Example 42, a comparative hydroxyl group-terminated urethane prepolymer having a branching degree α of more than 0.8 is used by using an active hydrogen group-containing compound (HY) having a branching degree of more than 0.5 and a polyisocyanate (N). UPC-2) was obtained.
In Comparative Examples 1 and 2 using the hydroxyl group-terminated urethane prepolymer (UPC-1) or (UPC-2) for comparison, the obtained pressure-sensitive adhesive sheet had initial curability and removability (60 ° C.-90% RH). ) Was poor. The evaluation results were also poor for many other evaluation items.

The present invention is not limited to the above embodiments and examples, and the design can be appropriately changed as long as the gist of the present invention is not deviated.

This application claims priority on the basis of Japanese Application Japanese Patent Application No. 2020-12855 filed on June 30, 2020, and incorporates all of its disclosures herein.

10, 20 Adhesive sheet 11, 21 Base sheet 12, 22A, 22B Adhesive layer 13, 23A, 23B Release sheet

Claims (11)

1. A hydroxyl group-terminated urethane prepolymer (UPH) which is a reaction product of one or more active hydrogen group-containing compounds (H) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N).
   A pressure-sensitive adhesive containing the polyfunctional isocyanate compound (I).
   The hydroxyl group-terminated urethane prepolymer (UPH) is a pressure-sensitive adhesive having a branching degree of 0.2 to 0.8 as measured by the GPC-MALS method.
2. The active hydrogen group-containing compound (H) of one or more kinds contains 50% by mass or more of the active hydrogen group-containing compound (HX) having a branching degree of 0.5 or less as measured by the GPC-MALS method.
   The pressure-sensitive adhesive according to claim 1, wherein the hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of 0.2 to 0.6 as measured by the GPC-MALS method.
3. Claimed that one or more active hydrogen group-containing compounds (H) contain 50% by mass or more of an active hydrogen group-containing compound (HX-S) having a branching degree of 0.3 or less as measured by the GPC-MALS method. The pressure-sensitive adhesive according to 2.
4. One or more active hydrogen group-containing compounds (H) contain 50% by mass or more and less than 100% by mass of the active hydrogen group-containing compound (HX) having a branching degree of 0.5 or less as measured by the GPC-MALS method. The pressure-sensitive adhesive according to claim 2, wherein the active hydrogen group-containing compound (HY) having a branching degree of more than 0.5 as measured by the GPC-MALS method is contained in an amount of more than 0% by mass and less than 50% by mass.
5. The active hydrogen group-containing compound (H) of one or more kinds contains 50% by mass or more of the active hydrogen group-containing compound (HY) having a branching degree of more than 0.5 as measured by the GPC-MALS method.
   The pressure-sensitive adhesive according to claim 1, wherein the hydroxyl group-terminated urethane prepolymer (UPH) has a branching degree of more than 0.6 and 0.8 or less as measured by the GPC-MALS method.
6. Claimed that one or more active hydrogen group-containing compounds (H) contain 50% by mass or more of an active hydrogen group-containing compound (HY-L) having a branching degree of more than 0.6 as measured by the GPC-MALS method. The pressure-sensitive adhesive according to 5.
7. One or more active hydrogen group-containing compounds (H) contain 50% by mass or more and less than 100% by mass of the active hydrogen group-containing compound (HY) having a branching degree of more than 0.5 as measured by the GPC-MALS method. The pressure-sensitive adhesive according to claim 5, wherein the active hydrogen group-containing compound (HX) having a branching degree of 0.5 or less as measured by the GPC-MALS method is contained in an amount of more than 0% by mass and less than 50% by mass.
8. The pressure-sensitive adhesive according to any one of claims 1 to 7, further comprising a plasticizer.
9. The pressure-sensitive adhesive according to any one of claims 1 to 8, further comprising an antistatic agent.
10. The adhesion according to any one of claims 1 to 9, further comprising one or more antioxidants selected from the group consisting of antioxidants, hydrolysis resistant agents, ultraviolet absorbers, and light stabilizers. Agent.
11. A pressure-sensitive adhesive sheet containing 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 10.

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