CN113930177B - Adhesive and method for producing adhesive sheet - Google Patents

Abstract

The invention provides an adhesive and a method for producing an adhesive sheet, which can form an adhesive layer having good wettability, good bendability, good re-peelability, and little contamination of an adherend after re-peeling. An adhesive, comprising: a polyurethane polyol (a) which is a reaction product of a polyol (x) comprising a trifunctional or higher polyol (x 2) and a polyisocyanate (y); and a polyfunctional isocyanate compound (B), wherein the trifunctional or higher polyol (x 2) contains a trifunctional or higher polyether polyol (x 2H) having one or more ethyleneoxy groups in one molecule and a number average molecular weight of more than 3,000, and the polyisocyanate (y) contains a difunctional isocyanate compound (y 1).

Description

Adhesive and method for producing adhesive sheet

The invention is a divisional application of an invention patent application with the application number of 201810139057.8 and the invention name of 'adhesive and adhesive sheet' which is proposed on 2018, 2, 9 and 2018.

Technical Field

The present invention relates to an adhesive and a method for producing an adhesive sheet.

Background

Conventionally, as surface protection sheets for various members, adhesive sheets having an adhesive layer formed on a base sheet have been widely used. Examples of the adhesive include acrylic adhesives, silicone adhesives, and urethane adhesives. Acrylic adhesives have excellent adhesion, but have strong adhesion, and therefore have poor removability after being attached to an adherend. In particular, after a lapse of time under a high-temperature and high-humidity environment, the re-peelability further decreases due to an increase in adhesive force, and there is a tendency that the adherend is easily contaminated with an adhesive component remaining on the surface of the adherend after re-peeling. Also, silicone adhesives are likely to be contaminated with adherends, and silicone resins having low molecular weights may volatilize and adsorb on the surface of devices such as electronic components, thereby causing problems. In contrast, the urethane adhesive has good adhesion to an adherend and excellent removability, and the urethane resin is not easily volatilized.

In the present specification, "adhesive" refers to an adhesive having releasability (removable adhesive), and "adhesive sheet" refers to an adhesive sheet having releasability (removable adhesive sheet).

Flat panel displays such as Liquid Crystal Displays (LCDs) and organic electroluminescent displays (OELDs), and touch panel displays in which the flat panel displays and touch panels are combined, are widely used in electronic devices such as Televisions (TVs), personal Computers (PCs), cellular phones, and portable information terminals.

The urethane adhesive sheet can be suitably used as a surface protective sheet for flat panel displays, touch panel displays, and substrates produced or used in the production steps thereof (e.g., glass substrates, and ITO/glass substrates having an Indium Tin Oxide (ITO) film formed on a glass substrate), optical members, and the like.

The adhesive layer preferably has good wettability to an adherend such as glass, and air bubbles are not involved in the adhesion interface when the adhesive sheet is adhered to the adherend. In the urethane adhesive, a plasticizer may be added to improve wettability. However, when the plasticizer is added in a large amount, there is a possibility that the adherend may be contaminated with the adhesive component remaining on the surface of the adherend after the re-peeling. Therefore, the amount of the plasticizer added is preferably small, and more preferably no plasticizer is added. The urethane adhesive preferably has good wettability even in a formulation composition in which the amount of the plasticizer added is small/the plasticizer is preferably not added.

The adhesive sheet is sometimes attached to a display having a curved portion. In displays such as OELD, the use of a plastic film as a substrate can provide flexibility, and the adhesive sheet may be bent while being attached to a flexible adherend. In the adhesive sheet used for such applications, the adhesive layer preferably has good bendability which is difficult to peel off from the adherend.

The adhesive sheet preferably has good removability to be easily removable from an adherend when removed from the adherend.

As a method for producing a urethane adhesive, there is a method comprising: a method using a polyurethane polyol which is a reaction product of a polyol and a polyisocyanate, and a polyfunctional isocyanate compound; and a method of reacting a polyol with a polyfunctional isocyanate compound at once without using a polyurethane polyol (one shot method).

Generally, an adhesive layer using a urethane adhesive obtained by a single process is hard and cannot have good flexibility. In addition, the surface smoothness of the adhesive layer tends to be easily deteriorated by curing shrinkage.

The method using the polyurethane polyol is preferable because the adhesion and cohesive force are easily suitable. As the raw material polyol of the polyurethane polyol, a difunctional polyol and a trifunctional or higher polyol can be used in combination. In general, a bifunctional polyol has two-dimensional crosslinkability and can impart appropriate flexibility to an adhesive layer, and a trifunctional or higher polyol has three-dimensional crosslinkability and can impart appropriate hardness to an adhesive layer. By using these polyols in combination, an adhesive layer having appropriate cohesive force and adhesive force can be obtained.

Patent document 1 discloses a urethane adhesive containing: a urethane prepolymer (A) containing a polyether polyol (a) having an average number of functional groups per molecule of 2.2 to 3.4, a polyisocyanate compound (b), and a catalyst (c); and a polyfunctional isocyanate compound (B) (claim 1 in patent document 1).

In patent document 1, it is preferable that the polyether polyol (a) is a mixture of polyether diol and polyether triol (claim 3 in patent document 1).

Patent document 2 discloses a urethane adhesive containing a polyurethane resin (a), a polyfunctional isocyanate compound (B), and at least one compound (C) selected from a polyalkylene glycol compound, an epoxy compound, and a phosphate compound (claim 1 in patent document 2).

Patent document 2 discloses examples of synthesis of a polyurethane polyol using a difunctional polyol and a trifunctional or higher polyol in combination as a raw material polyol of the polyurethane polyol (synthesis examples 1 to 5).

The symbols of the various components in patent documents 1 and 2 are described as they are in the literature, and are not related to the symbols of the various components used in the adhesive of the present invention.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2006-182795

[ patent document 2] Japanese patent laid-open No. 2015-7226

Disclosure of Invention

[ problems to be solved by the invention ]

In patent document 1, it is preferable that the polyether diol is a difunctional polypropylene glycol (a 1) and the polyether triol is a trifunctional polypropylene glycol (a 2) (claim 4, synthesis example 1 to synthesis example 7 in patent document 1). In synthetic examples 1 to 7 of patent document 1, the number average molecular weight of polyether diol (a 1) is only 1,000, and the number average molecular weight of polyether triol (a 2) is 350 to 3,000. In examples 1 to 12 of patent document 1 in which the polyurethane polyols of synthesis examples 1 to 7 were used, no wetting agent was used.

According to the findings of the present inventors, the wettability of the urethane-based adhesive of examples 1 to 12 of patent document 1 is insufficient, and air bubbles are likely to be involved in a sticking interface when the adhesive sheet is stuck to an adherend (see comparative example 2 in [ example ] described later).

In synthetic examples 1 to 3 and 5 of patent document 2, adisco polyether (ADEKA polyether) AM-302 (trifunctional polypropylene glycol having a terminal ethylene oxide end cap, molecular weight 3,000, manufactured by adisco (ADEKA)) was used as a trifunctional or higher polyol.

According to the findings of the present inventors, it is difficult to form an adhesive layer having good flexibility in the urethane adhesives of examples 1 to 15, 17, and 18 of patent document 2 using the polyurethane polyols of synthesis examples 3 and 5 (see comparative example 1 in [ example ] described later). In addition, in the examples of patent document 2, there is also a problem that an adherend is contaminated with an adhesive remaining on the surface of the adherend after re-peeling because a plasticizer (component (C)) is used to improve wettability (see comparative example 1 in [ example ] described later).

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive agent capable of forming an adhesive layer having good wettability, good bendability, good re-peelability, and little contamination of an adherend after re-peeling.

[ means for solving the problems ]

The adhesive of the present invention is an adhesive comprising:

a polyurethane polyol (a) which is a reaction product of a polyol (x) comprising a trifunctional or higher polyol (x 2) and a polyisocyanate (y); and

a polyfunctional isocyanate compound (B), wherein in the adhesive,

the trifunctional or higher polyol (x 2) contains a trifunctional or higher polyether polyol (x 2) having one or more Ethyleneoxy (EO) groups in one molecule and a number average molecular weight (Mn) of more than 3,000 _H )，

The polyisocyanate (y) contains a difunctional isocyanate compound (y 1).

The adhesive of the present invention is a composition prepared by blending a plurality of materials including the component (a) and the component (B), but in the adhesive, a plurality of blending components including the component (a) and the component (B) may not be clearly present as independent components. That is, the adhesive of the present invention may contain a reaction product obtained by partially reacting a plurality of formulation components including the component (a) and the component (B).

The adhesive sheet of the present invention includes a substrate sheet and an adhesive layer containing a cured product of the adhesive of the present invention.

In general, a sheet is called a "tape", "film", or "sheet" in terms of thickness and width. In the present specification, the term "sheet" is used as a term indicating a concept including them, without particularly distinguishing them.

Unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present specification are polystyrene equivalent values obtained by Gel Permeation Chromatography (GPC) measurement, and can be measured by the method described in [ example ] below.

[ Effect of the invention ]

The present invention provides an adhesive that can form an adhesive layer having good wettability, good bendability, good removability, and little contamination of an adherend after removability.

Drawings

Fig. 1 is a schematic cross-sectional view of an adhesive sheet according to embodiment 1 of the present invention.

Fig. 2 is a schematic cross-sectional view of an adhesive sheet according to embodiment 2 of the present invention.

Description of the symbols

10. 20: adhesive sheet

11. 21: substrate sheet

12. 22A, 22B: adhesive layer

13. 23A, 23B: release sheet

Detailed Description

The adhesive of the invention is a carbamate adhesive, which comprises:

a polyurethane polyol (a) which is a reaction product of a polyol (x) comprising a trifunctional or higher polyol (x 2), and a polyisocyanate (y); and

a polyfunctional isocyanate compound (B) wherein,

the trifunctional or higher polyol (x 2) contains a trifunctional or higher polyether polyol (x 2) having one or more Ethyleneoxy (EO) groups in one molecule and a number average molecular weight (Mn) of more than 3,000 _H )，

The polyisocyanate (y) contains a difunctional isocyanate compound (y 1).

The adhesive of the present invention can solve the above-mentioned problems even when the amount of the plasticizer (P) added is small/preferably the adhesive is prepared without adding the plasticizer (P), but the plasticizer (P) may be prepared as needed without departing from the spirit of the present invention.

The adhesive sheet of the present invention is a urethane adhesive sheet, which comprises a base sheet and an adhesive layer containing a cured product of the adhesive of the present invention.

The adhesive sheet of the present invention can be used in the form of a tape, a label, a sheet, a double-sided tape, or the like. The adhesive sheet of the present invention can be suitably used as a surface protective sheet, a decorative sheet, an anti-slip sheet, and the like.

Flat panel displays such as Liquid Crystal Displays (LCDs) and organic electroluminescent displays (OELDs), and touch panel displays in which the flat panel displays and the touch panel are combined are widely used in electronic devices such as Televisions (TVs), personal Computers (PCs), mobile phones, and portable information terminals.

The adhesive sheet of the present invention can be suitably used as a surface protective sheet for flat panel displays, touch panel displays (these are also collectively referred to simply as "displays"), substrates produced or used in the production steps thereof (glass substrates, ITO/glass substrates having an ITO (indium tin oxide) film formed on a glass substrate, and the like), optical members, and the like.

Adhesive agent "

(polyurethane polyol (A))

The polyurethane polyol (a) is a reaction product obtained by copolymerizing one or more polyols (x) with one or more polyisocyanates (y). One or more of the polyurethane polyols (A) may be used. The copolymerization reaction may be carried out in the presence of a catalyst, if necessary. A solvent may be used as necessary in the copolymerization reaction.

< polyol (x) >

The polyol (x) comprises at least one or more trifunctional or higher polyol (x 2). Preferably, the polyol (x) comprises one or more difunctional polyols (x 1) and one or more trifunctional or more polyols (x 2).

The kind of the polyol (x) is not particularly limited, and there may be mentioned: polyester polyols, polyether polyols, polyacrylic polyols, polycaprolactone polyols, polycarbonate polyols, castor oil polyols, and the like. Among these, polyester polyols, polyether polyols, and combinations thereof are preferred.

The polyester polyol is a compound (esterified product) obtained by esterification reaction of at least one polyol component and at least one acid component, and can be used as is well known.

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

Examples of the acid component of the raw material include: succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1, 12-dodecanedioic acid, 1, 14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1, 4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1, 4-naphthalenedicarboxylic acid, 4' -biphenyldicarboxylic acid, and acid anhydrides thereof.

The polyether polyol may be one obtained by using a known compound containing active hydrogen having two or more active hydrogens in one molecule as an initiator and subjecting one or more oxirane compounds to addition polymerization (addition polymer).

Examples of the initiator include hydroxyl group-containing compounds and amines. Specifically, there may be mentioned: difunctional initiators such as Ethylene Glycol (EG), propylene Glycol (PG), 1, 4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine; trifunctional initiators such as glycerin, trimethylolpropane and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamines; pentafunctional initiators such as diethylenetriamine, and the like.

Examples of the oxirane compound include: alkylene Oxide (AO) such as Ethylene Oxide (EO), propylene Oxide (PO), and Butylene Oxide (BO); tetrahydrofuran (THF), and the like.

The polyether polyol is preferably an alkylene oxide adduct of an active hydrogen-containing compound (also referred to as a polyoxyalkylene-based polyol). Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol are preferable; and trifunctional polyether polyols such as alkylene oxide adducts of glycerin.

The number average molecular weight (Mn) of the polyol (x) is not particularly limited, and is preferably 200 to 25,000. When Mn is 200 or more, gelation of the polyurethane polyol (a) is effectively suppressed. When Mn is 25,000 or less, the cohesive force of the polyurethane polyol (a) becomes favorable.

In the case of using a polyester polyol and/or a polyether polyol as the polyol (x), preferred number average molecular weight (Mn) is as follows.

The number average molecular weight (Mn) of the polyester polyol is preferably 500 to 5,000, more preferably 600 to 4,000, and particularly preferably 800 to 3,000. When Mn is 500 or more, gelation of the polyurethane polyol (a) is effectively suppressed. When Mn is 5,000 or less, the cohesive force of the polyurethane polyol (a) becomes appropriate.

The number average molecular weight (Mn) of the polyether polyol is preferably from 500 to 5,000, more preferably from 600 to 4,000, and particularly preferably from 800 to 3,000. When Mn is 500 or more, gelation of the polyurethane polyol (a) is effectively suppressed. When Mn is 5,000 or less, the cohesive force of the polyurethane polyol (a) becomes appropriate.

As described above, in the present invention, at least one or more trifunctional or higher polyol (x 2) is used as the polyol (x).

It is preferable to use more than one difunctional polyol (x 1) in combination with more than one trifunctional or more than one trifunctional polyol (x 2). In general, the difunctional polyol (x 1) has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer, and the trifunctional or higher polyol (x 2) has three-dimensional crosslinkability and can impart appropriate hardness to the adhesive layer. By using these polyols in combination, an adhesive layer having appropriate cohesive force and adhesive force can be obtained.

In the present invention, the trifunctional or higher polyol (x 2) contains a trifunctional or higher polyether polyol (x 2) having one or more Ethyleneoxy (EO) groups in one molecule and a number average molecular weight (Mn) of more than 3,000 _H )。

As in patent documents 1 and 2 listed in the section of "background art", a urethane adhesive using a difunctional polyol and a trifunctional polyol containing an EO group or not containing an EO group as a raw material polyol of a polyurethane polyol has been conventionally known, but the number average molecular weight (Mn) of the trifunctional polyol used as the raw material polyol is 3,000 or less (see synthesis examples 1 to 7 and examples 1 to 12 of patent document 1, synthesis examples 1 to 3, synthesis example 5, and examples 1 to 15, 17, and 18 of patent document 2).

In the present invention, a trifunctional or higher polyether polyol (x 2) having a number average molecular weight (Mn) larger than that of the trifunctional polyols described in patent documents 1 and 2 is used _H ). By using a trifunctional or higher polyether polyol (x 2) having EO groups and a number average molecular weight (Mn) of more than 3,000 _H ) The raw material polyol of the polyurethane polyol (A) can provide an adhesive which can form an adhesive layer having good wettability even in a formulation composition in which the amount of the plasticizer (P) added is small/preferably no plasticizer (P) is added. For example, an adhesive layer in which bubbles are less likely to be involved in a bonding interface when bonding to an adherend such as a glass substrate or an ITO/glass substrate can be formed.

The adhesive sheet is sometimes attached to a display having a curved portion. In addition, in displays such as OELD, the use of a plastic film as a substrate can provide flexibility, and the adhesive sheet may be bent while being attached to a flexible adherend. In the adhesive sheet used for such applications, the adhesive layer preferably has good bendability which is difficult to peel off from the adherend.

By using a trifunctional or higher polyether polyol (x 2) having EO groups and a number average molecular weight (Mn) of more than 3,000 _H ) An adhesive which can form an adhesive layer having excellent flexibility is provided as a raw material polyol of the polyurethane polyol (A). By increasing the molecular weight of the trifunctional or higher polyol than before, the number of crosslinking points of the trifunctional or higher polyol can be reduced, and as a result, the pressure-sensitive adhesive layer exhibits properties close to those of elasticity/rubber elasticity, and the flexibility of the pressure-sensitive adhesive layer is considered to be improved.

Further, by using trifunctional or higher polyether polyol (x 2) having EO group and number average molecular weight (Mn) exceeding 3,000 _H ) As a source of the polyurethane polyol (A)The polyol can improve the removability of the adhesive layer and can form an adhesive layer which can be easily removed again. By using (using a relatively large amount of) a trifunctional or higher polyol, the polymer network of the adhesive layer can be appropriately three-dimensionally transformed, and therefore, it is considered that the removability of the adhesive layer will be improved.

Trifunctional or higher polyether polyol (x 2) for improving wettability, bendability, and removability _H ) The number average molecular weight (Mn) of (B) is preferably 4,000 or more, more preferably 5,000 or more, particularly preferably 6,000 or more.

Trifunctional or higher polyether polyol (x 2) _H ) The upper limit of the number average molecular weight (Mn) of (C) is not particularly limited. Trifunctional or higher polyether polyol (x 2) for making the cohesive force of the polyurethane polyol (A) suitable _H ) The number average molecular weight (Mn) of (B) is preferably 25,000 or less, more preferably 20,000 or less, particularly preferably 15,000 or less, most preferably 10,000 or less.

In the present invention, the trifunctional or higher polyol (x 2) may contain a trifunctional or higher polyether polyol (x 2) having an EO group and a number average molecular weight (Mn) of more than 3,000 _H ) And a trifunctional or higher polyol (x 2) having a number average molecular weight (Mn) of 3,000 or less _L )。

As the trifunctional or higher polyol (x 2), only a polyether polyol (x 2) having a relatively large molecular weight is used _H ) In the case of (2), the adhesive force of the adhesive layer tends to be high. By using a polyol (x 2) having a smaller molecular weight in combination _L ) The use of polyether polyols (x 2) having a higher molecular weight can be reduced _H ) And the adhesion of the increased adhesive layer is adjusted to be within a suitable range. Further, a trifunctional or higher polyol (x 2) _L ) May or may not have an EO group.

The trifunctional or higher polyether polyol having an EO group is a compound (addition polymer) obtained by addition polymerization of one or more oxirane compounds containing Ethylene Oxide (EO) with the trifunctional or higher initiator. Among them, a compound (addition polymer) obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) and the trifunctional or higher initiator is preferable.

The trifunctional or higher polyether polyol having an EO group preferably has an EO group at least at the end. Examples of the trifunctional or higher polyether polyol having at least an EO group at the end thereof include a glycerin EO adduct obtained by addition polymerization of glycerin with one or more Ethylene Oxides (EO), a glycerin PO — EO adduct obtained by addition polymerization of glycerin with one or more Propylene Oxides (PO) and one or more Ethylene Oxides (EO) in the stated order (also referred to as "glycerin polypropylene glycol end glycol modification"), and the like.

The difunctional polyol (x 1) is preferably one or more polyols selected from the group consisting of difunctional polyether polyols and difunctional polyester polyols.

The difunctional polyol (x 1) preferably contains a difunctional polyether polyol from the viewpoint of adhesion to a substrate, suppression of contamination by an adherend, and the like.

As the bifunctional polyether polyol, a bifunctional polyether polyol having an EO group is preferable in terms of more effectively suppressing contamination by an adherend.

The difunctional polyether polyol having an EO group is a compound (addition polymer) obtained by addition polymerization of one or more oxirane compounds containing Ethylene Oxide (EO) with the difunctional initiator. Among them, a polyalkylene glycol obtained by addition polymerization of one or more Alkylene Oxides (AO) containing Ethylene Oxide (EO) with the bifunctional initiator is preferable. The more the content of EO groups in the polyalkylene glycol is, the more preferable. The difunctional polyether polyol having an EO group is particularly preferably polyethylene glycol (PEG) in terms of the EO group content. That is, the one or more difunctional polyether polyols having EO groups preferably comprise PEG. The upper limit of the amount of EO groups in the trifunctional or higher polyether polyol having EO groups is not particularly limited, but is preferably 50 mass% in the molecular weight of the polyol.

The number-average molecular weight (Mn) of the difunctional polyol (x 1) is preferably from 200 to 6,000, more preferably from 200 to 4,000, particularly preferably from 200 to 2,000.

From the viewpoint of the balance between the cohesive force and the adhesive force,

when the total amount of the polyols (x) is set to 100 parts by mass,

preferably, the amount of the difunctional polyol (x 1) is 0 to 90 parts by mass, the amount of the trifunctional or higher polyol (x 2) is 100 to 10 parts by mass,

more preferably, the amount of the difunctional polyol (x 1) is 5 to 70 parts by mass, the amount of the trifunctional or higher polyol (x 2) is 95 to 30 parts by mass,

particularly preferably, the amount of the difunctional polyol (x 1) is 10 to 50 parts by mass, and the amount of the trifunctional or higher polyol (x 2) is 90 to 50 parts by mass.

From the viewpoint of the balance among cohesive force, adhesive force, wettability, bendability, and removability,

when the total amount of the polyols (x) is set to 100 parts by mass,

it is preferable that the amount of the bifunctional polyol (x 1) is from 0 to 90 parts by mass and the trifunctional or higher polyether polyol (x 2) _H ) The amount of the polyol (x 2) is 100 to 5 parts by mass and is a trifunctional or higher polyol _L ) The amount of (B) is 0 to 50 parts by mass,

when the total amount of the polyols (x) is set to 100 parts by mass,

more preferably, the amount of the difunctional polyol (x 1) is 2 to 70 parts by mass and the trifunctional or higher polyether polyol (x 2) _H ) The amount of the (B) is 98 to 25 parts by mass, and the amount of the polyol (x 2) is not less than three functional groups _L ) The amount of (B) is 0 to 40 parts by mass,

when the total amount of the polyols (x) is set to 100 parts by mass,

particularly preferably, the amount of the difunctional polyol (x 1) is 5 to 50 parts by mass and the trifunctional or higher polyether polyol (x 2) _H ) The amount of the (C) polyol (x 2) is 95 to 50 parts by mass, and the amount of the polyol is three or more functional groups _L ) The amount of (B) is 0 to 30 parts by mass.

The amount of the trifunctional or higher polyol (x 2) is preferably set to be more than the amount of the difunctional polyol (x 1). This further improves the elastomer-like properties of the pressure-sensitive adhesive layer.

< polyisocyanate (y) >

The polyisocyanate (y) may be a known polyisocyanate, and examples thereof include: aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, and alicyclic polyisocyanate.

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

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

Examples of the aromatic aliphatic polyisocyanate include: omega, omega '-diisocyanate-1, 3-dimethylbenzene, omega' -diisocyanate-1, 4-diethylbenzene, 1, 4-tetramethylxylene diisocyanate, 1, 3-tetramethylxylene diisocyanate, and the like.

Examples of the alicyclic polyisocyanate include: 3-isocyanatomethyl-3, 5-trimethylcyclohexyl isocyanate, 1, 3-cyclopentane diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, methyl-2, 6-cyclohexane diisocyanate, 4' -methylenebis (cyclohexyl isocyanate), and 1, 4-bis (isocyanatomethyl) cyclohexane, and the like.

Further, as the polyisocyanate, an isocyanate prepolymer may be used. The isocyanate prepolymer is obtained by prepolymerizing diisocyanate as a raw material so that the monomer content is 1% or less. Examples of the isocyanate prepolymer include an adduct, a biuret, and an isocyanurate.

The adduct is diisocyanate and trimethylolpropane (CH) ₃ -CH ₂ -C(CH ₂ -OH) ₃ ) An adduct of (a). The biuret body is a reactant of diisocyanate and water or tertiary alcohol. The isocyanurate body is a trimer of diisocyanates (the trimer comprising an isocyanurate ring).

The polyisocyanate (y) is preferably 4,4' -diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3, 5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), or the like.

In the polymerization of the polyurethane polyol (a), the blending ratio of the polyol (x) and the polyisocyanate (y) is preferably set so that the number of moles of hydroxyl groups exceeds the number of moles of isocyanate groups. The ratio of the number of moles of hydroxyl groups in the polyol (x) to the number of moles of isocyanate groups in the polyisocyanate (y) (NCO/OH ratio) is preferably 0.3 to 0.95, more preferably 0.4 to 0.85. When the hydroxyl group and the isocyanate group are reacted at an appropriate ratio, both the cohesive force and the adhesive force can be highly compatible.

In the present invention, the polyisocyanate (y) contains one or more difunctional isocyanate compounds (y 1).

The polyisocyanate (y) is preferably used only as the difunctional isocyanate compound (y 1). The polyisocyanate (y) may optionally contain one or more trifunctional or higher isocyanate compounds.

When only a trifunctional or higher polyol having high crosslinkability is used as the raw material polyol of the polyurethane polyol and only a trifunctional or higher polyisocyanate is used, the molecular structure of the polyurethane polyol may become rigid and the cohesive force of the adhesive layer may become higher than an appropriate range.

In the adhesive of the present invention using a trifunctional or higher polyol as the raw material polyol of the polyurethane polyol, excessive crosslinking can be suppressed and an adhesive layer having preferable cohesive and adhesive forces can be obtained by using one or more polyisocyanates containing a difunctional isocyanate compound (y 1) as the polyisocyanate (y), preferably using only the difunctional isocyanate compound (y 1).

< catalyst >

The catalyst may be any known catalyst, and examples thereof include tertiary amine compounds and organometallic compounds.

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

Examples of the organometallic compound include tin compounds and non-tin compounds.

Examples of the tin-based compound include: dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate (dibutyl tin dimaleate), dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide (tributyltin ethoxide), tributyltin ethoxide (tributyltin ethoxide), dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate, and the like.

Examples of the non-tin compound include: titanium systems such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead-based materials such as lead oleate, lead 2-ethylhexoate, lead benzoate, and lead naphthenate; iron series such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt systems such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc systems such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium-based compounds such as zirconium naphthenate.

More than one catalyst may be used. When the reactivity of each of the plural kinds of polyols (x) used in combination as required is different, gelation or clouding of the reaction solution may easily occur in a single catalyst system due to the difference in reactivity. In such a case, by using two catalysts, it is easy to control the reaction (e.g., reaction speed, etc.), so that the problem can be solved. The combination of the two catalysts is not particularly limited, and tertiary amine/organic metal system, tin system/non-tin system, tin system/tin system, and the like can be mentioned. Tin-based/tin-based is preferred, and dibutyltin dilaurate and tin 2-ethylhexanoate are more preferred.

The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate/dibutyltin dilaurate) is not particularly limited, but is preferably more than 0 and less than 1, and more preferably 0.2 to 0.6. If the mass ratio is less than 1, the balance of the catalyst activity is good, gelation and clouding of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

The amount of the one or more catalysts used is not particularly limited, but is preferably 0.01 to 1% by mass based on the total amount of the polyol (x) and the polyisocyanate (y).

< solvent >

A solvent may be used as necessary in the polymerization of the polyurethane polyol (A). The solvent may be any of the known ones, and examples thereof include: methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, and the like. In terms of solubility of the polyurethane polyol (a), boiling point of the solvent, and the like, ethyl acetate, toluene, and the like are particularly preferable.

< polymerization Process >

The polymerization method of the polyurethane polyol (a) is not particularly limited, and known polymerization methods such as bulk polymerization and solution polymerization can be applied.

The polymerization order is not particularly limited, and there may be mentioned:

sequence 1) a sequence in which the polyol (x), the polyisocyanate (y), the optional catalyst, and the optional solvent are all charged into a flask;

sequence 2) a sequence in which the polyol (x), if necessary, the catalyst, and if necessary, the solvent are charged into a flask, and the polyisocyanate (y) is added dropwise thereto.

The sequence 2) is preferable in terms of ease of control of the reaction.

The reaction temperature when the catalyst is used is preferably less than 100 ℃ and more preferably from 85 ℃ to 95 ℃. When the reaction temperature is less than 100 ℃, the reaction rate, the crosslinked structure, and the like can be easily controlled, and the polyurethane polyol (a) having a desired molecular weight can be easily produced.

When no catalyst is used, the reaction temperature is preferably 100 ℃ or higher, more preferably 110 ℃ or higher, and the reaction time is preferably 3 hours or longer.

The weight-average molecular weight (Mw) of the polyurethane polyol (A) is preferably from 1 to 50 ten thousand, more preferably from 3 to 40 ten thousand, and particularly preferably from 5 to 35 ten thousand. When the Mw of the polyurethane polyol (a) is within an appropriate range, good coatability can be easily obtained.

(polyfunctional isocyanate Compound (B))

As the polyfunctional isocyanate compound (B), known ones can be used, and compounds exemplified for the polyisocyanate (y) which is a raw material of the polyurethane polyol (a) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, alicyclic polyisocyanate, and trimethylolpropane adduct/biuret/trimer thereof) can be used.

The amount of the polyfunctional isocyanate compound (B) is preferably 1 to 50 parts by mass, more preferably 1 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, based on 100 parts by mass of the polyurethane polyol (a). When the amount of the polyfunctional isocyanate compound (B) is 1 part by mass or more, the cohesive force of the adhesive layer becomes good, and when it is 50 parts by mass or less, the adhesive force of the adhesive layer becomes good.

(plasticizer (P))

As described above, the present invention can provide an adhesive having good wettability even in a formulation composition in which the amount of the plasticizer (P) added is small/preferably no plasticizer (P) is added. Therefore, in the adhesive of the present invention, the plasticizer (P) is not an essential component for improving wettability, but the adhesive of the present invention may optionally contain one or more plasticizers (P). However, in the case of adding the plasticizer (P), the amount thereof can be suppressed to a low level. The amount of the plasticizer (P) relative to 100 parts by mass of the polyurethane polyol (a) may be, for example, 50 parts by mass or less (0 to 50 parts by mass), preferably 40 parts by mass or less (0 to 40 parts by mass), more preferably 30 parts by mass or less (0 to 30 parts by mass), further preferably 20 parts by mass or less (0 to 20 parts by mass), particularly preferably 10 parts by mass or less (0 to 10 parts by mass), most preferably 5 parts by mass or less (0 to 5 parts by mass).

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

Examples of esters of mono-or polybasic acids with alcohols include: isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, diisodecyl adipate, diisostearyl adipate, dibutyl sebacate, diisocetyl sebacate, tributyl acetylcitrate, tributyl trimellitate, trioctyl trimellitate, trihexyl trimellitate, triolenyl trimellitate, and triisocetyl trimellitate.

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

Examples of esters of mono-or polybasic acids with polyalkylene glycols include: polyethylene glycol dihexyl acid, polyethylene glycol di-2-ethylhexyl acid, polyethylene glycol dilaurate, polyethylene glycol dioleate, and polyethylene glycol dimethyl adipate.

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

(solvent)

The adhesive of the present invention may optionally contain a solvent. The solvent may be any of the known ones, and examples thereof include: methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, and the like. In view of the solubility of the polyurethane polyol (a), the boiling point of the solvent, and the like, ethyl acetate, toluene, and the like are particularly preferable.

(antideteriorant (D))

The adhesive of the present invention may optionally contain one or more anti-deterioration agents (D). This can suppress deterioration of various properties of the adhesive layer due to long-term use. Examples of the anti-deterioration agent (D) include: hydrolysis resistance agents, antioxidants, ultraviolet absorbers, light stabilizers, and the like.

< hydrolysis resistance agent >

In the case where a carboxyl group is generated by a hydrolysis reaction of the adhesive layer under a high-temperature and high-humidity environment, a hydrolysis resistant agent may be used in order to block the carboxyl group.

As hydrolysis resistance agents, there can be mentioned: carbodiimide, isocyanate, oxazoline, and epoxy. Among them, carbodiimide-based ones are preferable from the viewpoint of hydrolysis-inhibiting effect.

The carbodiimide-based hydrolysis inhibitor is a compound having one or more carbodiimide groups in one molecule.

Examples of the monocarbodiimide compound include: dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, and naphthylcarbodiimide, etc.

The polycarbodiimide compound may be produced by subjecting a diisocyanate to a decarbonylation condensation reaction in the presence of a carbodiimidization catalyst. Examples of the diisocyanate include: 4,4' -diphenylmethane diisocyanate, 3' -dimethoxy-4, 4' -diphenylmethane diisocyanate, 3' -dimethyl-4, 4' -diphenylmethane diisocyanate, 4' -diphenylether diisocyanate, 3' -dimethyl-4, 4' -diphenylether diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 1-methoxyphenyl-2, 4-diisocyanate, isophorone diisocyanate, 4' -dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, and the like. Examples of the carbodiimidization catalyst include: and phospholene oxides such as 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and 3-phospholene isomers thereof.

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

Examples of the oxazoline hydrolysis inhibitor include: 2,2 '-o-phenylenebis (2-oxazoline), 2' -m-phenylenebis (2-oxazoline), 2 '-p-phenylenebis (4-methyl-2-oxazoline) 2,2' -m-phenylbis (4-methyl-2-oxazoline), 2 '-p-phenylbis (4, 4' -dimethyl-2-oxazoline), 2 '-m-phenylbis (4, 4' -dimethyl-2-oxazoline) 2,2 '-ethylenebis (2-oxazoline), 2' -tetramethylenebis (2-oxazoline), 2 '-hexamethylenebis (2-oxazoline), 2' -octamethylenebis (2-oxazoline), 2 '-ethylenebis (4-methyl-2-oxazoline), and 2,2' -diphenylenebis (2-oxazoline), and the like.

Examples of the epoxy hydrolysis inhibitor include: diglycidyl ethers of aliphatic diols such as 1, 6-hexanediol, neopentyl glycol, and polyalkylene glycols; polyglycidyl ethers of aliphatic polyhydric alcohols such as sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, and trimethylolpropane; polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol; diglycidyl esters or polyglycidyl esters of aliphatic or aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, and sebacic acid; diglycidyl ethers or polyglycidyl ethers of polyphenols such as resorcinol, bis- (p-hydroxyphenyl) methane, 2-bis- (p-hydroxyphenyl) propane, tris- (p-hydroxyphenyl) methane, and 1, 2-tetrakis (p-hydroxyphenyl) ethane; n-glycidyl derivatives of amines such as N, N-diglycidylaniline, N-diglycidyltoluidine, and N, N' -tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl derivatives of aminophenols; triglycidyl tris (2-hydroxyethyl) isocyanurate, and triglycidyl isocyanurate; epoxy resins such as o-cresol type epoxy resins and phenol novolac type epoxy resins.

The amount of the hydrolysis resistance agent added is not particularly limited, but is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4.5 parts by mass, and particularly preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the polyurethane polyol (a).

< antioxidant >

Examples of the antioxidant include a radical scavenger and a peroxide decomposer. Examples of the radical scavenger include phenol compounds and amine compounds. Examples of the peroxide decomposer include sulfur compounds and phosphorus compounds.

Examples of the phenolic compound include: 2, 6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2, 6-di-tert-butyl-4-ethylphenol, stearyl β - (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 2 '-methylenebis (4-methyl-6-tert-butylphenol), 2' -methylenebis (4-ethyl-6-tert-butylphenol), 4 '-thiobis (3-methyl-6-tert-butylphenol), 4' -butylidenebis (3-methyl-6-tert-butylphenol), 3, 9-bis [1, 1-dimethyl-2- [ β - (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] ethyl ]2,4,8, 10-tetraoxaspiro [5,5] undecane, phenylpropionic acid, 3, 5-bis (1, 1-dimethylethyl) -4-hydroxy-, C7-C9 side chain alkyl ester, 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, ethylene glycol bis [3,3' -bis- (4 '-hydroxy-3' -t-butylphenyl) butyrate ], a salt thereof with a carboxylic acid, a salt thereof, a hydrate thereof, a salt thereof, a hydrate thereof, a crystalline solid thereof, and a crystalline solid thereof, 1,3, 5-tris (3 ',5' -di-tert-butyl-4 ' -hydroxybenzyl) -S-triazine-2, 4,6- (1H, 3H, 5H) trione, tocopherol, and the like.

Examples of the phosphorus-based compound include: triphenyl phosphite, diphenylisodecyl phosphite, 4' -butylidene-bis (3-methyl-6-tert-butylphenyl ditridecyl) phosphite, cyclic neopentane-tetrakis (octadecyl phosphite), tris (nonylphenyl) phosphite, tris (monononylphenyl) phosphite, tris (dinonylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10- (3, 5-di-tert-butyl-4-hydroxybenzyl) -9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9, 10-dihydro-9-oxa-10-phosphaphenanthrene, tris (2, 4-di-tert-butylphenyl) phosphite, cyclic neopentane-tetrakis (2, 6-di-tert-butyl-4-methylphenyl) phosphite, and 2, 2-methylenebis (4, 6-di-tert-butylphenyl) phosphite, etc.

By using the antioxidant, thermal deterioration of the polyurethane polyol (a) can be prevented, and bleeding of the plasticizer (P) from the adhesive layer can be effectively suppressed.

The amount of the antioxidant to be added is not particularly limited, but is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and particularly preferably 0.2 to 2 parts by mass, based on 100 parts by mass of the polyurethane polyol (a).

As the antioxidant, one or more phenol compounds as a radical scavenger are preferably used from the viewpoint of stability and antioxidant effect, and more preferably one or more phenol compounds as a radical scavenger and one or more phosphorus compounds as a peroxide decomposer are used in combination. In addition, it is particularly preferable to use a phenol compound as a radical scavenger in combination with a phosphorus compound as a peroxide decomposer, and to use these antioxidants in combination with the hydrolysis resistant agent.

< ultraviolet absorber >

Examples of the ultraviolet absorber include: benzophenone compounds, benzotriazole compounds, salicylic acid compounds, oxalanilide compounds, cyanoacrylate compounds, and triazine compounds.

The amount of the ultraviolet absorber added is not particularly limited, but is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2.5 parts by mass, and particularly preferably 0.2 to 2 parts by mass, based on 100 parts by mass of the polyurethane polyol (a).

< light stabilizer >

Examples of the light stabilizer include hindered amine compounds and hindered piperidine compounds. The amount of the light stabilizer to be added is not particularly limited, but is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and particularly preferably 0.2 to 1 part by mass, based on 100 parts by mass of the polyurethane polyol (a).

(antistatic agent (E))

The adhesive of the present invention may optionally contain more than one antistatic agent (E).

Examples of the antistatic agent include inorganic salts, polyol compounds, ionic liquids, and surfactants, and among them, ionic liquids are preferred. The "ionic liquid" is also referred to as an ambient temperature molten salt, and is a salt having fluidity at 25 ℃.

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

Examples of the polyol compound include: propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, trimethylolpropane, pentaerythritol, and the like.

Examples of the ionic liquid containing an imidazole ion include: 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1, 3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, and the like.

Examples of the ionic liquid containing pyridine ions include: 1-methylpyridine bis (trifluoromethylsulfonyl) imide, 1-butylpyridine bis (trifluoromethylsulfonyl) imide, 1-hexylpyridine bis (trifluoromethylsulfonyl) imide, 1-octylpyridine bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridine hexafluorophosphate, 1-octyl-4-methylpyridine bis (trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridine bis (fluorosulfonyl) imide, 1-methylpyridine bis (perfluoroethylsulfonyl) imide, and 1-methylpyridine bis (perfluorobutylsulfonyl) imide, and the like.

Examples of the ionic liquid containing an ammonium ion include: trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, tri-N-butylmethylammonium bis (trifluoromethanesulfonyl) imide, and the like.

Further, commercially available ionic liquids such as pyrrolidine salts, phosphonium salts, and sulfonium salts can be suitably used.

Surfactants are classified into low-molecular surfactants and high-molecular surfactants. Either type is nonionic, anionic, cationic, and amphoteric.

Examples of the nonionic low-molecular-weight surfactant include: glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine fatty acid ester, and fatty acid diethanolamide.

Examples of the anionic low-molecular-weight surfactant include: alkyl sulfonates, alkylbenzene sulfonates, and alkyl phosphates, and the like.

Examples of the cationic low-molecular-weight surfactant include: tetraalkylammonium salts, trialkylbenzylammonium salts, and the like.

Examples of the amphoteric low-molecular-weight surfactant include alkylbetaines and alkylimidazolidines.

Examples of the nonionic polymer surfactant include: polyether ester amide type, ethylene oxide-epichlorohydrin type, polyether ester type, and the like.

Examples of the anionic polymeric surfactant include polystyrene sulfonic acid type surfactants.

The cationic polymer surfactant may be an acrylate polymer type having a quaternary ammonium salt group.

Examples of the amphoteric polymeric surfactant include: and amino acid type amphoteric surfactants such as higher alkyl aminopropionates, betaine type amphoteric surfactants such as higher alkyl dimethyl betaines and higher alkyl dihydroxyethyl betaines, and the like.

The amount of the antistatic agent (E) added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, per 100 parts by mass of the polyurethane polyol (a).

(leveling agent)

The adhesive of the present invention may optionally contain a leveling agent. By adding the leveling agent, the leveling property of the adhesive layer can be improved. Examples of the leveling agent include an acrylic leveling agent, a fluorine leveling agent, and a silicone leveling agent. From the viewpoint of suppressing contamination of an adherend after the adhesive sheet is peeled off again, an acrylic leveling agent or the like is preferable.

The weight average molecular weight (Mw) of the leveling agent is not particularly limited, but is preferably 500 to 20,000, more preferably 1,000 to 15,000, and particularly preferably 2,000 to 10,000. When Mw is 500 or more, the amount of vaporization from the coating layer during heating and drying of the coating layer can sufficiently suppress contamination of the surroundings. When Mw is 20,000 or less, the leveling property of the adhesive layer is effectively improved.

The amount of the leveling agent is not particularly limited, and is preferably 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, based on 100 parts by mass of the polyurethane polyol (a), from the viewpoints of suppressing contamination of an adherend after the adhesive sheet is peeled off again and improving the leveling property of the adhesive layer.

(other optional Components)

The adhesive of the present invention may optionally contain other optional components within a range not impairing the effects of the present invention. As other optional components, there may be mentioned: a catalyst, a resin other than the urethane resin, a filler (talc, calcium carbonate, titanium oxide, or the like), a metal powder, a colorant (pigment, or the like), a foil, a softening agent, a conductive agent, a silane coupling agent, a lubricant, an anticorrosive agent, a heat-resistant stabilizer, a weather-resistant stabilizer, a polymerization inhibitor, an antifoaming agent, or the like.

Adhesive sheet "

The adhesive sheet of the present invention includes a substrate sheet and an adhesive layer containing a cured product of the adhesive of the present invention. The adhesive layer may be formed on one or both sides of the substrate sheet. The exposed surface of the adhesive layer may be covered with a release sheet as necessary. Further, the release sheet is peeled off when the adhesive sheet is attached to the adherend.

Fig. 1 is a schematic cross-sectional view of an adhesive sheet according to embodiment 1 of the present invention. In fig. 1, reference numeral 10 denotes an adhesive sheet, reference numeral 11 denotes a base sheet, reference numeral 12 denotes an adhesive layer, and reference numeral 13 denotes a release sheet. The adhesive sheet 10 is a single-sided adhesive sheet having an adhesive layer formed on one side of a base sheet.

Fig. 2 is a schematic cross-sectional view of an adhesive sheet according to embodiment 2 of the present invention. In fig. 2, reference numeral 20 denotes an adhesive sheet, reference numeral 21 denotes a base sheet, reference numerals 22A and 22B denote adhesive layers, and reference numerals 23A and 23B denote release sheets. The adhesive sheet 20 is a double-sided adhesive sheet in which adhesive layers are formed on both sides of a base sheet.

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

The resin constituting the resin sheet is not particularly limited, and examples thereof include: ester-based resins such as polyethylene terephthalate (PET); olefin resins such as Polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride; amide resins such as nylon 66; urethane resin (including foam); combinations of these, and the like.

The thickness of the resin sheet other than the polyurethane sheet is not particularly limited, but is preferably 15 to 300. Mu.m. The thickness of the polyurethane sheet (including the foam) is not particularly limited, and is preferably 20 to 50,000. Mu.m.

The paper is not particularly limited, and there may be mentioned: plain paper, coated paper, and the like.

The constituent metal of the metal foil is not particularly limited, and examples thereof include: aluminum, copper, combinations of these, and the like.

As described above, the adhesive of the present invention has excellent substrate adhesiveness, and therefore, the adhesive sheet of the present invention is preferable because the substrate sheet used is highly flexible in selection.

The release sheet is not particularly limited, and a known release sheet having a surface of a resin sheet, paper, or the like subjected to a known release treatment such as coating with a release agent can be used.

The adhesive sheet can be produced by a known method.

First, the adhesive of the present invention is applied to the surface of a substrate sheet to form a coating layer containing the adhesive of the present invention. The coating method may be any known method, and examples thereof include a roll coater method, a comma coater method, a die coater method, a reverse coater method, a screen printing method, and a gravure coater method.

Next, the coating layer is dried and cured to form an adhesive layer containing a cured product of the adhesive of the present invention. The heating and drying temperature is not particularly limited, but is preferably about 60 ℃ to 150 ℃.

The thickness of the adhesive layer can be suitably designed according to the use of the adhesive sheet, and is, for example, about 5 μm to 300 μm. In the present specification, the "thickness of the adhesive layer" is a thickness after drying unless otherwise specified.

Next, a release sheet is attached to the exposed surface of the adhesive layer by a known method as needed.

A single-sided adhesive sheet can be produced in the above manner.

By performing the above operation on both sides, a double-sided adhesive sheet can be manufactured.

In contrast to the above method, the adhesive of the present invention may be applied to the surface of a release sheet to form a coating layer containing the adhesive of the present invention, the coating layer may be dried and cured to form an adhesive layer containing a cured product of the adhesive of the present invention, and finally a substrate sheet may be laminated on the exposed surface of the adhesive layer.

As described above, according to the present invention, an adhesive agent that can form an adhesive layer having good wettability, good bendability, good re-peelability, and little contamination of an adherend after re-peeling can be provided.

According to the present invention, it is possible to provide an adhesive agent which can form an adhesive layer having good wettability, good bendability, good re-peelability, and little contamination of an adherend after re-peeling, even in a formulation composition in which the amount of plasticizer added is small/preferably no plasticizer added.

[ examples ]

Synthetic examples, examples of the present invention, and comparative examples are explained below. In the following description, "part" means "part by mass" and "%" means "% by mass" unless otherwise specified.

[ measurement of molecular weight ]

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by a Gel Permeation Chromatography (GPC) method. The measurement conditions are as follows. Furthermore, mw and Mn are both polystyrene equivalent values.

The device comprises the following steps: shimadzu excellence (Shimadzu project) (manufactured by Shimadzu corporation),

Pipe column: three Soidex LF-804 (manufactured by Showa Denko K.K.) were connected in series, and a detector: a differential refractive index detector,

Solvent: tetrahydrofuran (THF),

Flow rate: 0.5mL/min,

Temperature of the solvent: at 40 deg.C,

Sample concentration: 0.02 percent,

Sample injection amount: 200 μ L.

[ Material ]

The materials used are as follows.

< difunctional polyol (x 1) >)

(x 1-1): sannesus PP-400 (polyether polyol, number average molecular weight Mn400, hydroxyl number 2, EO-free, available from Sanyo chemical industries, ltd.),

(x 1-2): sannesus PP-1000 (polyether polyol, number average molecular weight Mn1000, hydroxyl number 2, EO-free, available from Sanyo chemical industries, ltd.),

(x 1-3): (Kuraray Polyol) P-1010 (polyether Polyol, number average molecular weight Mn1000, hydroxyl number 2, EO group-free, manufactured by Kuraray Co., ltd.),

(x 1-4): (ii) Coloray Polyol (Kuraray Polyol) P-4010 (polyether Polyol, number average molecular weight Mn4000, hydroxyl number 2, EO group-free, manufactured by Coloray (Kuraray) Co., ltd.),

(x 1-5): PEG-400 (polyether polyol, number average molecular weight Mn400, hydroxyl number 2, EO group-containing, manufactured by Toho chemical industries Co., ltd.),

(x 1-6): PEG-1000 (polyether polyol, number average molecular weight Mn1000, hydroxyl number 2, EO group-containing, manufactured by Toho chemical industries Co., ltd.),

(x 1-7): pluronic 5001F (polyether polyol, number average molecular weight Mn4000, hydroxyl number 2, EO group-containing, manufactured by Asahi glass Co., ltd.).

< trifunctional or higher polyol (x 2) >)

(x 2-1): primaminol 7012 (polyether polyol, number average molecular weight Mn10000, hydroxyl number 3, EO group-containing, manufactured by Asahi glass Co., ltd.),

(x 2-2): acinosanol 851 (polyether polyol, mn6700 number average molecular weight, 3 hydroxyl group, EO group-containing, manufactured by Asahi glass Co., ltd.),

(x 2-3): acrosonol 828 (a polyether polyol having a number average molecular weight Mn5000 and a hydroxyl number of 3, EO group-containing, manufactured by Asahi glass Co., ltd.),

(x 2-4): adeca polyether (ADEKA polyether) AM-302 (polyether polyol, number average molecular weight Mn3000, hydroxyl number 3, EO group-containing, manufactured by Adeca (ADEKA) Inc.),

(x 2-5): acrosso (Excenol) 5030 (polyether polyol, number average molecular weight Mn5100, hydroxyl number 3, EO-free, manufactured by Asahi glass Co., ltd.),

(x 2-6): DK Polyol (DK Polyol) G480 (polyether Polyol, number average molecular weight Mn350, hydroxyl number 3, EO group-free, first Industrial pharmaceutical Co., ltd.).

< polyisocyanate (y) > (

(y-1): desmodur (Desmodur) H (hexamethylene diisocyanate, manufactured by Sumika Covestro Co., ltd.),

(y-2): takenate (Takenate) 500 (xylylene diisocyanate, manufactured by Mitsui chemical Co., ltd.),

(y-3): summir HT (trimethylolpropane adduct of hexamethylene diisocyanate, nonvolatile matter 75%, manufactured by Sumika Covestro).

< polyfunctional isocyanate Compound (B) > (

(B-1): sumidur HT (trimethylolpropane adduct of hexamethylene diisocyanate, nonvolatile matter: 75%; manufactured by Sumika Covestro Ltd.),

(B-2): takenate (Takenate) D-110N (trimethylolpropane adduct of xylylenediisocyanate, nonvolatile matter of which is 75%, manufactured by Mitsui chemical Co., ltd.),

(B-3): cronate (Coronate) HX (an isocyanurate of hexamethylene diisocyanate, 100% of nonvolatile matter, manufactured by tokyo corporation).

< Antifogery agent (D) >

(D-1): iollonus (IRGANOX) 1010 (manufactured by BASF corporation), a hindered phenol-based antioxidant.

< plasticizer (P) >)

(P-1): mosaize (Monocizer) W262 (manufactured by Diegon (DIC)), a polyether ester compound,

(P-2): unister M-183 (manufactured by Nippon oil Co., ltd.), methyl oleate.

< antistatic agent (E) >)

(E-1): ionic liquid, tri-n-butyl methyl ammonium bis (trifluoromethanesulfonyl) imide.

(Synthesis example 1)

2 parts of a difunctional polyol (x 1-1), 98 parts of a trifunctional polyol (x 2-1) and 1.0 part of a difunctional polyisocyanate (y-1) (NCO/OH amount: 0.5) were put into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer and a dropping funnel. 100 parts of toluene, 0.03 part of dibutyltin dilaurate as a catalyst, and 0.01 part of tin 2-ethylhexanoate were added thereto, and the temperature was slowly raised to 90 ℃ to carry out a reaction at 90 ℃ for 2 hours. Sampling was performed as needed, and after disappearance of the remaining isocyanate group was confirmed by Infrared absorption (IR) spectroscopy, the reaction solution was cooled to terminate the reaction. A solution (nonvolatile content: 50%) of the polyurethane polyol (A-1) was obtained in the above manner. The Mw of the obtained polyurethane polyol (A-1) was 75,000. The formulation composition and Mw of the obtained polyurethane polyol (A-1) are shown in Table 1-1. In tables 1-1 to 1-4 and tables 2-1 to 2-4, the unit of the amount of blending is [ parts ].

The amount of the bifunctional polyisocyanate (y-1) can be calculated as follows.

((y-1) parts amount) [ parts ] = in

(NCO/OH ratio) × ((molecular weight of (y-1)/((NCO base number of (y-1))

[ ((x 1-1) parts)/((x 1-1) molecular weight) × ((x 1-1) hydroxyl number)

+ ((amount of (x 2-1)/((molecular weight of (x 2-1) × ((hydroxyl number of x 2-1))

＝0.5×168/2×(2/400×2+98/10000×3)

About 1.7 parts

(Synthesis examples 2 to 21, 31 and 32)

Solutions of the polyurethane polyols (A-2) to (A-21), the polyurethane polyol (H-1), and the polyurethane polyol (H-2) were obtained in the same manner as in Synthesis example 1, except that the formulation compositions shown in tables 1-1 to 1-4 were changed in Synthesis examples 2 to 21, 31, and 32. In each synthesis example, the Mw of the obtained polyurethane polyol is shown in tables 1-1 to 1-4.

(example 1)

A urethane adhesive was obtained by mixing 100 parts of the solution of the polyurethane polyol (a-1) obtained in synthesis example 1, 10 parts of the polyfunctional isocyanate compound (B-1), 1.0 part of the antioxidant (D-1), and 100 parts of ethyl acetate as a solvent, and stirring the mixture with a disperser. The amounts of the respective materials other than the solvent used are expressed in terms of nonvolatile components. The formulation composition is shown in Table 2-1.

A50 μm-thick polyethylene terephthalate film (PET film, produced by Lumiror T-60: toray corporation) was prepared as a substrate sheet. The obtained adhesive was applied to one surface of the substrate sheet so that the thickness of the dried adhesive layer became 12 μm, and dried at 100 ℃ for two minutes to form an adhesive layer. A release sheet (Super Stik) SP-PET38 manufactured by Lintec) having a thickness of 38 μm was attached to the adhesive layer to obtain an adhesive sheet. Cured for 1 week at 23 ℃ -50% RH for various evaluations.

(examples 2 to 23, comparative examples 1 to 2)

In each of examples 2 to 23 and comparative examples 1 to 2, an adhesive and an adhesive sheet were obtained in the same manner as in example 1 except that the formulation composition was changed as shown in tables 2-1 to 2-4.

Comparative example 3

A urethane adhesive was obtained by mixing 100 parts of a trifunctional polyol (x 2-2), 12.6 parts of a polyfunctional isocyanate compound (B-3), 0.04 parts of dibutyltin dilaurate as a catalyst, and 210 parts of ethyl acetate as a solvent, and stirring the mixture with a disperser. The amount of each material other than the solvent used is expressed in terms of nonvolatile content. The formulation compositions are shown in tables 2 to 3.

An adhesive sheet was obtained in the same manner as in example 1, except that the obtained urethane adhesive was used and the drying condition of the adhesive layer was set to 130 ℃.

[ evaluation items and evaluation methods ]

The evaluation items and evaluation methods are as follows.

(removability)

The obtained adhesive sheet was prepared in a width of 25mm and a length of 100mm, and used as a measurement sample. Subsequently, the release sheet was peeled from the test sample in an atmosphere of 23 to 50% rh, and the exposed adhesive layer was adhered to a sodium hydroxide glass plate and pressure-bonded using a 2kg roller. Thereafter, the mixture was left for 24 hours under RH conditions of 60 to 90% by volume. After air-cooling for 30 minutes in an environment of 23 to 50% RH, the adhesion was measured under conditions of a peeling speed of 300mm/min and a peeling angle of 180 ℃ using a tensile tester (Tensilon): measure machine (ORIENTEC) in accordance with Japanese Industrial Standards (JIS) Z0237. Moreover, the lower adhesion makes re-peeling easier. The evaluation criteria are as follows.

Excellent: less than 10mN/25mm, and excellent.

O: it is preferably 10mN/25mm or more and less than 20mN/25 mm.

And (delta): is not less than 20mN/25mm and less than 50mN/25mm, and is practical.

X: more than 50mN/25mm, it is not practical.

(wettability)

The obtained adhesive sheet was prepared in a size of 50mm in width and 100mm in length and used as a measurement sample. Then, the test piece was left to stand in an RH-equivalent range of 23 to 50% for 30 minutes, and then peeled from the test sample. Both ends of the adhesive sheet were held with both hands while the center portion of the exposed adhesive layer was brought into contact with the glass plate, and then both hands were released. The time until the entire adhesive layer was brought into close contact with the glass plate by the weight of the test sample was measured, and the wettability of the adhesive was evaluated. The shorter the time until the glass plate is brought into close contact with the glass plate, the better the wettability (affinity) to the glass, and therefore the glass can be protected well in the production process using the glass. The evaluation criteria are as follows.

Excellent: it is excellent when the time required for the adhesion is less than 2 seconds.

O: it is preferable that the time required for the adhesion is 2 seconds or more and less than 3 seconds.

And (delta): it is practical that the time until the contact is made is 3 seconds or more and less than 5 seconds.

X: it is not practical to seal for 5 seconds or more.

(flexibility)

The obtained adhesive sheet was prepared in a size of 10mm in width and 100mm in length and used as a measurement sample. Subsequently, the peeling pieces were peeled from the test specimens in an environment of 23 to 50% RH. Then, an adhesive sheet sample having a length of half the circumference and a width of 10mm was attached along the circumferential surface of a glass cylinder (diameter: 15 mm). After leaving for 72 hours under the condition of 60 to 90% RH, the bulge state of the measurement sample was observed. When the bulge was observed at the end, the length of the bulge portion was measured. The evaluation criteria are as follows.

Very good: the end portion has no projection, and the whole of the measurement sample is closely adhered to the end portion, and the measurement sample is excellent.

O: the end part is slightly convex, and the protrusion is less than 0.3mm, which is good.

And (delta): the end part is provided with a small amount of bulges, and the bulges exceed 0.3mm and are less than 1mm, so that the utility model is practical.

X: the end part is provided with a bulge which exceeds 1mm and is not practical.

(substrate adhesion)

After the releasable sheet was peeled off from the obtained adhesive sheet, the exposed adhesive layer was rubbed back and forth with a finger to evaluate whether or not the adhesive layer was peeled off from the base sheet. The evaluation criteria are as follows.

Excellent: even if 30 cycles or more, the adhesive does not fall off from the substrate sheet, and is excellent.

O: the adhesive was well detached from the substrate sheet in 21 to 30 passes.

And (delta): the adhesive comes off from the substrate sheet in 11 to 20 passes, and is practical.

X: the adhesive comes off from the substrate sheet within 10 passes, and is not practical.

(staining by adherend)

The obtained adhesive sheet was prepared in a size of 70mm in width and 100mm in length and used as a measurement sample. Subsequently, the release sheet was peeled from the measurement sample in an environment of 23 to 50% rh, and the exposed adhesive layer was attached to a sodium hydroxide glass plate and pressure-bonded using a laminator. Thereafter, the mixture was left for 72 hours under RH conditions of 60 to 90% by volume. After air-cooling for 1 hour in an environment of 23 to 50% rh, the measurement sample was peeled from the glass plate, and the portion of the glass surface to which the measurement sample was attached was irradiated with a Light Emitting Diode (LED) lamp in a dark room, and the contamination state was visually evaluated. The evaluation criteria are as follows.

Very good: no contamination was observed on the glass surface, and it was excellent.

O: foreign matter or turbidity was observed slightly on one portion of the glass surface, which was good.

And (delta): it is practical to slightly observe foreign matters or turbidity on 2 to 3 portions of the glass surface.

X: it is not practical to observe a little foreign matter or turbidity at 4 or more portions of the glass surface and a clearly visible foreign matter or turbidity at 3 or less portions.

[ evaluation results ]

The evaluation results are shown in tables 2-1 to 2-4.

In examples 1 to 23, the following adhesive was produced, which contains:

a polyurethane polyol (a) which is a reaction product of a polyol (x) comprising a trifunctional or higher polyol (x 2) and a polyisocyanate (y); and

a polyfunctional isocyanate compound (B) wherein,

the trifunctional or higher polyol (x 2) contains a trifunctional or higher polyether polyol (x 2) having EO groups and Mn exceeding 3,000 _H )，

The polyisocyanate (y) contains a difunctional isocyanate compound.

The evaluation results of the removability after storage under 60 to 90% RH, wettability to glass, bendability after storage under 60 to 90% RH, substrate adhesiveness, and staining of the adherend after storage under 60 to 90% RH of each of the adhesive sheets obtained in examples 1 to 23 were good.

In comparative example 1, a comparative polyurethane polyol which is a reaction product of a difunctional polyol, a trifunctional polyol having an EO group and an Mn of 3,000 or less, and a difunctional polyisocyanate was used to produce an adhesive. The adhesive sheet obtained in comparative example 1 was poor in the results of the evaluation of bendability after storage under 60 to 90% RH and staining of adherend after storage under 60 to 90% RH.

In comparative example 2, a comparative polyurethane polyol, which is a reaction product of a difunctional polyol, a trifunctional polyol having no EO group and having an Mn of more than 3,000, and a difunctional polyisocyanate, was used to produce an adhesive. The adhesive sheet obtained in comparative example 2 was poor in the evaluation result of wettability to glass.

In comparative example 3, instead of using the polyurethane polyol, a trifunctional polyol having an EO group and an Mn exceeding 3,000 and a polyfunctional isocyanate compound were used to produce an adhesive by a single process. The adhesive sheet obtained in comparative example 3 was poor in the results of the evaluation of bendability and substrate adhesiveness after storage under 60 to 90% RH.

[ tables 1-1]

[ tables 1-2]

[ tables 1 to 3]

[ tables 1 to 4]

[ Table 2-1]

[ tables 2 to 2]

[ tables 2 to 3]

[ tables 2 to 4]

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

Claims (4)

1. An adhesive, comprising: a polyurethane polyol (a) which is a reaction product of a trifunctional or higher polyol (x 2) with a polyisocyanate (y); and

a polyfunctional isocyanate compound (B), wherein in the adhesive,

the trifunctional or higher polyol (x 2) is a trifunctional or higher polyether polyol (x 2) having one or more ethyleneoxy groups in one molecule and a number average molecular weight of 6,000 or more _H )，

The polyisocyanate (y) contains a difunctional isocyanate compound (y 1).

2. The adhesive of claim 1, further comprising one or more deterioration prevention agents selected from the group consisting of an antioxidant, a hydrolysis resistance agent, an ultraviolet absorber, and a light stabilizer.

3. The adhesive of claim 1 or 2, further comprising an antistatic agent.

4. A method for producing an adhesive sheet, comprising:

a coating step of coating the adhesive according to any one of claims 1 to 3 on at least one surface of a substrate sheet to form a coating layer;

a hardening step of drying and hardening the coating layer to form an adhesive layer; and

and a sticking step of sticking a release sheet to the exposed surface of the adhesive layer.

Images