JP2020132799A - Adhesive and adhesive sheet and methods of use thereof - Google Patents

Abstract

To provide an adhesive capable of forming an adhesive layer, wherein the adhesive layer has good wetting and spreading property to an adherend and is adhered to the adherend with an adhesive force which is not easily peeled off while having repeelability which can be readhered to the adherend before the adhesive layer is irradiated with active energy rays, and wherein the adhesive layer is irradiated with active energy rays to effectively weaken an adhesive force thereby being easily peeled off from the adherend.SOLUTION: The adhesive of the present invention is a reaction product of one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule and one or more kind of polyisocyanate (N), and contains a hydroxy group-terminated urethane prepolymer (UPH) containing no (meth) acryloyl group, a polyfunctional isocyanate compound (I), and a radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups in one molecule. An adhesive layer (12) comprising a cured product of the adhesive of the present invention is irradiated with active energy rays to weaken an adhesive force.SELECTED DRAWING: None

Description

The present invention relates to an adhesive, an adhesive sheet, and a method of using the adhesive.

Conventionally, as a surface protection sheet for various members, an adhesive sheet in which an adhesive layer is formed on a base material sheet has been widely used. 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 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 manufacturing 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 to form an adhesive sheet roll, and a curing step of curing the adhesive sheet roll.

International Publication No. 2011/121303 International Publication No. 2016/092971 Japanese Unexamined Patent Publication No. 2014-196383

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 manufactured or used in these manufacturing processes (glass substrates, and ITO / glass substrates on which an ITO (indium tin oxide) film is formed on the glass substrate. Etc.) and is suitably used as a surface protection sheet for optical members and the like.

In the manufacturing process of a flat panel display, a touch panel display, or the like, in order to improve productivity, it is preferable that the adherend with an adhesive sheet can be conveyed at high speed to a processing unit that performs a necessary process. For example, an automatic high-speed transfer is being studied in which an adherend with an adhesive sheet is adsorbed from the adhesive sheet side using a vacuum suction member, lifted, and transported to a desired location. In this automatic high-speed transfer, it is preferable that the adherend with the adhesive sheet has a relatively high adhesive force in which the adhesive sheet does not peel off from the adherend while being adsorbed by the vacuum suction member. On the other hand, in the adherend with an adhesive sheet that has completed the necessary steps, the adhesive sheet preferably has a relatively low adhesive force so that the adhesive sheet can be peeled off at high speed.

Patent Document 1 includes a base adhesive polymer, a curable molecule that can be cured by free radical polymerization, a photoinitiator, and an internal cross-linking agent that can be cured by a mechanism other than free radical polymerization. The adhesive composition is disclosed (claim 1).
The peeling strength decreases due to the polymerization of curable molecules by light irradiation. The rate of decrease in peel strength after light irradiation is, for example, 30 to 98%, preferably 50 to 95% (claims 15 and 16).
The composition described in Patent Document 1 is preferably for a medical adhesive dressing (claim 25).
The base adhesive polymer is preferably a polyacrylate (claim 8). In the section of [Example], only an acrylic pressure-sensitive adhesive containing a polyacrylate as a base adhesive polymer is produced. Since the acrylic adhesive has high adhesive strength, it does not have good wettability and spreadability to the adherend, and it is difficult to apply it neatly without entraining air bubbles. Acrylic adhesives also have high adhesive strength, so that they do not have good removability after being attached to an adherend, and it is difficult to reattach them.
For example, in the acrylic pressure-sensitive adhesive sheet manufactured in Example 8 of Patent Document 1, the adhesive strength before light irradiation is about 1200 to 100 gf / 25 mm, and the adhesive strength after light irradiation is about 100 to 30 gf / 25 mm. (Converted from the data in Table 11). Since this acrylic adhesive sheet has a very high adhesive force before light irradiation, it does not have good wettability and removability. Although the adhesive strength of this acrylic adhesive sheet is reduced by light irradiation, the adhesive strength after light irradiation is still high, and it is difficult to perform high-speed peeling.

Patent Document 2 describes a urethane resin (A) having a hydroxyl group and a (meth) acryloyl group, a polyisocyanate cross-linking agent (B), a (meth) acrylic compound (C) having two or more (meth) acryloyl groups, and an organic substance. An ultraviolet curable pressure-sensitive adhesive composition containing a solvent (D) and a photopolymerization initiator (E) is disclosed (claim 1).
Patent Document 2 discloses a method for producing an ultraviolet curable pressure-sensitive adhesive sheet in which the organic solvent (D) is dried after the above-mentioned ultraviolet curable pressure-sensitive adhesive composition is applied to a base material (claim 9). .. Further, there is disclosed a method for producing a laminate in which two or more adherends are bonded together using the ultraviolet curable pressure-sensitive adhesive sheet and then irradiated with ultraviolet rays (claim 10).
The pressure-sensitive adhesive described in Patent Document 2 is intended for OCA (Optical Clear Adhesive) applications (paragraph 0002), and is not intended for re-peeling applications. The pressure-sensitive adhesive sheet for OCA is required to have high step followability when it is attached to an adherend, while it is required not to be peeled off again after adhering two or more adherends. In Patent Document 2, before irradiation with ultraviolet rays, the crosslink density is designed to be low with an emphasis on step followability, and the crosslink density is increased by irradiation with ultraviolet rays to reduce re-peelability.
In the section of [Example] of Patent Document 2, only a bifunctional polyol is used as a raw material polyol of the urethane resin (A) in order to suppress the crosslink density before irradiation with ultraviolet rays.
In Patent Document 2, both the urethane resin (A) and the (meth) acrylic compound (C), which is a photopolymerizable monomer, have a (meth) acryloyl group, so that the crosslink density of the adhesive layer after ultraviolet irradiation is increased. It is effectively enhanced (paragraph 0014). However, when both the urethane resin (A) and the (meth) acrylic compound (C) which is a photopolymerizable monomer have a (meth) acryloyl group, the reactivity becomes too high, and the light of the fluorescent lamp and the sun The reaction may easily start and proceed by irradiation with a small amount of ultraviolet rays contained in ambient light such as light, and the adhesive strength may decrease. It is not preferable that the adhesive strength of the adhesive layer is reduced by irradiation with a small amount of ultraviolet rays contained in the ambient light during vacuum adsorption and transportation of the adherend.

In Patent Document 3, 30 to 80 parts by weight of a photopolymerizable monomer (B) having one (meth) acryloyl group is added to 100 parts by weight of the urethane resin (A), and the photopolymerization initiator (C) is used. A pressure-sensitive adhesive containing 0.05 to 3 parts by weight of the silane coupling agent (D) and 0.1 to 5 parts by weight of the silane coupling agent (D) is disclosed (claim 1).
In the section of [Example] of Patent Document 3, the number of functional groups of the photopolymerizable monomer (B) used is 1 to 2. In this case, the cross-linking of the adhesive layer by light irradiation may be insufficient, and the decrease in adhesive force after light irradiation may be insufficient for high-speed peeling.
The reference numerals of the respective components described in Patent Documents 1 to 3 are the codes described in these documents, and have nothing to do with the reference numerals used for each component of the present invention.

The present invention has been made in view of the above circumstances, and has good wettability and spreadability on the adherend before irradiation with active energy rays such as ultraviolet rays, and can be reattached to the adherend. While having re-peelability, it can be attached to the adherend with an adhesive force that does not easily peel off, and after irradiation with active energy rays, the adhesive force is effectively reduced and the adherend can be easily attached. It is an object of the present invention to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer that can be peeled off.
The present invention also has good wettability and spreadability on the adherend before irradiation with active energy rays such as ultraviolet rays, and has removability that can be reattached to the adherend. An adhesive sheet that can be attached to the body with an adhesive force that does not easily peel off, and after irradiation with active energy rays, the adhesive force is effectively reduced and can be easily peeled off from the adherend. The purpose is to provide.

The adhesive of the present invention
A hydroxyl group that is a reaction product of one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N) and does not contain a (meth) acryloyl group. Terminal urethane prepolymer (UPH) and
A removable pressure-sensitive adhesive containing a polyfunctional isocyanate compound (I).
Further, one molecule contains a radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups.
The pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive has a reduced adhesive strength due to irradiation with active energy rays.

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

The method of using the adhesive sheet of the present invention is as follows.
The process of attaching the adhesive sheet to the surface of the adherend, and
A step of irradiating the adhesive sheet attached to the surface of the adherend with active energy rays to reduce the adhesive force of the adhesive sheet.
The step includes a step of peeling the pressure-sensitive adhesive sheet having reduced adhesive strength from the adherend.

Unless otherwise specified in the present specification, "adhesive strength" shall be determined by the method described in the section of [Example].

According to the present invention, before irradiation with active energy rays such as ultraviolet rays, the adherend has good wettability and spreadability, and the adherend has re-peelability that can be reattached. An adhesive layer that can be attached to the adherend with an adhesive force that does not easily peel off, and that the adhesive force is effectively reduced after irradiation with active energy rays and can be easily peeled off from the adherend. A pressure-sensitive adhesive that can be formed can be provided.
According to the present invention, before irradiation with active energy rays such as ultraviolet rays, the adherend has good wettability and spreadability, and the adherend has removability that can be reattached. Adhesion that can be attached to the adherend with adhesive strength that does not easily peel off, and after irradiation with active energy rays, the adhesive strength is effectively reduced and can be easily peeled off from the adherend. Sheets can be provided.

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.

[Adhesive]
The adhesive of the present invention
A hydroxyl group that is a reaction product of one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N) and does not contain a (meth) acryloyl group. Terminal urethane prepolymer (UPH) and
Polyfunctional isocyanate compound (I) and
It is a removable urethane-based pressure-sensitive adhesive containing a radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups in one molecule.
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 a cured product of the above-mentioned pressure-sensitive adhesive of the present invention.
The pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention can have a reduced adhesive strength after irradiation with respect to before irradiation with active energy rays.

(Hydroxyl-terminated urethane prepolymer (UPH))
The hydroxyl-terminated urethane prepolymer (UPH) is a reaction product obtained by copolymerizing one or more active hydrogen group-containing compounds (HX) with one or more polyisocyanates (N). The copolymerization reaction can be carried out in the presence of one or more catalysts, if necessary. One or more kinds of solvents can be used for the copolymerization reaction, if necessary. Hydroxyl-terminated urethane prepolymers (UPH) do not contain (meth) acryloyl groups.

<Active hydrogen group-containing compound (HX)>
The active hydrogen group-containing compound (HX) 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, and an amino group (in the present specification, the amino group includes an imino group unless otherwise specified) and the like. Examples of the active hydrogen group-containing compound (HX) 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 (HX) 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 (HX) include polyester polyol, polyether polyol, polyacrylic polyol, polycaprolactone polyol, polycarbonate polyol, and castor oil-based polyol. Of these, polyester polyols, polyether polyols, and combinations thereof are preferable. The active hydrogen group-containing compound (HX) of one or more kinds preferably contains a polyether polyol.

As the polyester polyol that can be used as the active hydrogen group-containing compound (HX), 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, trimethylpropane, pentaerythritol and the like. 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 (HX), known ones can be used. Examples of the polyether polyol include a compound (addition polymer) 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-containing compound is preferable. Among them, polyethylene glycol (PEG), polypropylene glycol (PPG), PPG (PPG-EO) having ethylene oxide (EO) added to the end, and bifunctional polyether polyols such as polyalkylene glycols such as polytetramethylene glycol; A trifunctional polyether polyol such as an alkylene oxide adduct of glycerin is preferable.

Examples of polyamines that can be used as the active hydrogen group-containing compound (HX) 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-nonanedimine, 1,10-decanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecan 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, dimethyleneamine with norbornan skeleton, metaxylylene diamine (MXDA), hexamethylenediamine carbamate, diethylenetriamine, triethylenetetramine, tetraethylenepenta Amines and aliphatic polyamines such as pentaethylenehexamine; 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 3,3' -Diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-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 active hydrogen group-containing compounds (HX) 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 polythiols that can be used as the active hydrogen group-containing compound (HX) include methanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 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-propadithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1,2- Benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4'-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiaidazole, 1,8 -Dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, 2-di-n-butylamino-4,6-dimercapto-s-triazine, and thiol group-terminated polymers (polysulfide polymer, etc.) And so on.

One or more active hydrogen group-containing compounds (HX) can include bifunctional active hydrogen group-containing compounds and / or trifunctional or higher functional hydrogen group-containing compounds. 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 functional 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 (HX), the adhesive strength, cohesive strength, removability and other properties 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, one or more active hydrogen group-containing compounds (HX) include a bifunctional active hydrogen group-containing compound and a trifunctional or higher functional hydrogen group-containing compound. Is preferable.

The number average molecular weight (Mn) of the active hydrogen group-containing compound (HX) is not particularly limited. The Mn of the active hydrogen group-containing compound (HX) is preferably 50 to 20000, more preferably 100 to 7000, and particularly preferably 400 to 5000, because the adhesive strength and wettability of the adhesive layer are preferable.

<Polyisocyanate (N)>
Known polyisocyanates (N) can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

Examples of the aromatic polyisocyanate include 1,3-phenylenediocyanate, 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-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4', 4 "-Triphenylmethane triisocyanate, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diisocyanate, 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-butylene diisocyanate, 1,3-butylene diisocyanate, 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.

In addition, 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-terminated urethane prepolymer (UPH) is as follows.
The ratio (NCO / H 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 (HX) is 0. It is preferable to determine the raw material compounding ratio so that it is 20 to 0.95, more preferably 0.40 to 0.80. The closer the NCO / H ratio is to 1, the more likely it is to gel during the synthesis of the hydroxyl-terminated urethane prepolymer (UPH). When the NCO / H ratio is 0.95 or less, gelation during the synthesis of hydroxyl-terminated urethane prepolymer (UPH) can be effectively suppressed.

<Catalyst>
One or more catalysts can be used for the polymerization of the hydroxyl-terminated urethane prepolymer (UPH), if necessary. 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 dibutyl titanium dichloride, tetrabutyl titanate, 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; zinc naphthenate and the like Examples include zirconium.
The type and amount of the catalyst added can be appropriately designed within a range in which the reaction proceeds well.

When multiple types of active hydrogen group-containing compounds (HX) with different reactivity are used in combination, there is a risk that poor polymerization stability or cloudiness of the reaction solution may occur in a single catalyst system due to these differences in reactivity. is there. In this case, by using two or more kinds of catalysts, the reaction (for example, reaction rate) can be easily controlled, and the above problem can be solved. In a system in which a plurality of types of active hydrogen group-containing compounds (HX) 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 dioctyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dioctyltin dilaurate (tin 2-ethylhexanoate / dioctyltin dilaurate) is not particularly limited and is preferably more than 0 and less than 1, more preferably 0.2 to 0.8. is there. When the mass ratio is less than 1, the balance of catalytic activity is good, gelation and white turbidity 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 (HX) 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-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-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

<Polymerization method of hydroxyl-terminated urethane prepolymer (UPH)>
The polymerization method of the hydroxyl-terminated urethane prepolymer (UPH) is not particularly limited, and known polymerization methods such as a massive polymerization method and a solution polymerization method can be applied.
As a polymerization procedure of hydroxyl-terminated urethane prepolymer (UPH),
Procedure 1) One or more active hydrogen group-containing compounds (HX), one or more polyisocyanates (N), one or more catalysts if necessary, and one or more solvents as needed. Procedure for filling in a flask;
Step 2) One or more active hydrogen group-containing compounds (HX), one or more catalysts if necessary, and one or more solvents if necessary 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).
When a plurality of active hydrogen group-containing compounds (HX) and / or polyisocyanates (N) are used, the reaction may be carried out in a plurality of steps.

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-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), known compounds can be used, and the compounds exemplified as the polyisocyanate (N) which is the raw material of the hydroxyl group-terminated urethane prepolymer (UPH) (specifically, aromatic polyisocyanate and aliphatic Polyisocyanates, aromatic aliphatic polyisocyanates, alicyclic polyisocyanates, and trimethylolpropanadducts / biuret / allophanates / trimerics thereof can be used.

(Radical Polymerizable Monomer (MX))
The pressure-sensitive adhesive of the present invention contains a radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups in one molecule. As used herein, the term "(meth) acryloyl group" means an acryloyl group and a methacryloyl group.
The radically polymerizable monomer (MX) is a material that polymerizes and cures by irradiation with active energy rays such as ultraviolet rays and electron beams in the presence of a radical polymerization initiator (R), if necessary. The radically polymerizable monomer (MX) is preferably ultraviolet curable, which is cured by ultraviolet irradiation.

In the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive of the present invention containing a radical-polymerizable monomer (MX), the pressure-polymerizable monomer (MX) is subjected to irradiation with active energy rays after being attached to an adherend and used. ), The adhesive layer is cured, the adhesive strength of the adhesive layer is reduced, and the adhesive sheet can be easily peeled off from the adherend.
In the present invention, since a trifunctional or higher functional radical polymerizable monomer (MX) containing three or more (meth) acryloyl groups is used, the cross-linking reaction proceeds during the polymerization of the radical polymerizable monomer (MX), resulting in adhesion. It is possible to effectively cure the layer and thereby reduce the adhesive strength. The number of (meth) acryloyl groups contained in the radically polymerizable monomer (MX) is preferably four or more, and more, because the curing of the adhesive layer and the resulting decrease in adhesive strength can be caused more effectively. It is preferably 5 or more. Since the adhesive layer can be cured and the adhesive strength can be reduced more effectively, the amount of the radically polymerizable monomer (MX) containing 5 or more (meth) acryloyl groups is a radically polymerizable simple substance. It is preferably 20% by mass or more, more preferably 40% by mass or more, particularly preferably 60% by mass or more, and most preferably 80% by mass or more, based on the total amount of the body (MX).

The radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups in one molecule is not particularly limited, and known ones can be used. Specifically, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene oxide-modified trimethylol propanetri (meth) acrylate, propylene oxide-modified trimethyl propanetri (meth) acrylate. ) Acrylate, Tris (acryloxyethyl) isocyanurate, Tris (2-hydroxyethyl) isocyanurate Tri (meth) acrylate, Caprolactone-modified tris (acryloxyethyl) isocyanurate, Trimethylol ethanetri (meth) acrylate, Pentaerythritol tetra (Meta) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, alkyl-modified dipentaerythritol tri (meth) acrylate, alkyl-modified dipentaerythritol tetra (meth) acrylate Polyhydric alcohols and (meth) acrylics such as meta) acrylates, alkyl-modified dipentaerythritol penta (meth) acrylates, caprolactone-modified dipentaerythritol hexa (meth) acrylates, and 1,2,3-cyclohexanetetra (meth) acrylates. Ester compound with acid; polyurethane poly (meth) acrylate, polyester poly (meth) acrylate, polyether poly (meth) acrylate, polyacrylic poly (meth) acrylate, polyalkid poly (meth) acrylate, polyepoxy poly (meth) Examples thereof include polyfunctional poly (meth) acrylate compounds such as acrylate, polyspiroacetal poly (meth) acrylate, polybutadiene poly (meth) acrylate, polythiol polyene poly (meth) acrylate, and polysilicon poly (meth) acrylate. These can be used alone or in combination of two or more.

The radically polymerizable monomer (MX) preferably contains an active hydrogen group such as a hydroxyl group and an amino acid. In this case, at the time of polymerization of the radically polymerizable monomer (MX), a part of the radically polymerizable monomer (MX) can be bonded to the urethane resin via the polyfunctional isocyanate compound (I), and the adhesive layer It is possible to more effectively cause the curing of the polymer and the resulting decrease in adhesive strength.
It is particularly preferable that the radically polymerizable monomer (MX) contains a hydroxyl group. Examples of the radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups and hydroxyl groups include tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipenta. Examples thereof include erythritol tetra (meth) acrylate and dipentaerythritol penta (meth) acrylate. These can be used alone or in combination of two or more.

In Patent Document 2 mentioned in the section of [Background Art], the urethane resin (A) and the (meth) acrylic compound (C), which is a photopolymerizable monomer, both have a (meth) acryloyl group, so that ultraviolet rays are emitted. The crosslink density of the adhesive layer after irradiation is effectively increased (paragraph 0014). However, when both the urethane resin (A) and the (meth) acrylic compound (C) which is a photopolymerizable monomer have a (meth) acryloyl group, the reactivity becomes too high, and the light of the fluorescent lamp and the sun The reaction may easily start and proceed by irradiation with a small amount of ultraviolet rays contained in ambient light such as light, and the adhesive strength may decrease. It is not preferable that the adhesive strength of the adhesive layer is reduced by irradiation with a small amount of ultraviolet rays contained in the ambient light during vacuum adsorption and transportation of the adherend.
In the present invention, since the hydroxyl-terminated urethane prepolymer (UPH) does not contain a (meth) acryloyl group, it is possible to suppress the cross-linking reaction due to irradiation with a small amount of ultraviolet rays contained in ambient light, and vacuum adsorption and transfer of the adherend. It is possible to prevent the adherend from peeling off from the adhesive sheet at times.

(Radical Polymerization Initiator (R))
If necessary, the pressure-sensitive adhesive of the present invention can contain a radical polymerization initiator (R) that initiates the polymerization of the radically polymerizable monomer (MX) when irradiated with active energy rays. When the radically polymerizable monomer (MX) is ultraviolet curable, the pressure-sensitive adhesive of the present invention is also referred to as a radical polymerization initiator (R) (in this case, the radical polymerization initiator (R) is also a photopolymerization initiator (RL). It is preferable to include.).

The radical polymerization initiator (R) is not particularly limited, and known radical polymerization initiators (R) can be used. For example, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1-one, and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one Acetphenone-based polymerization initiators such as; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin-based polymerization initiators such as benzyl dimethyl ketal; benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-methylbenzophenone, etc. Benzophenone-based polymerization initiators such as 4-phenylbenzophenone, hydroxybenzophenone, acrylicized benzophenone, and 4-benzoyl-4'-methyldiphenylsulfide; thioxanthone, 2-chlorthioxanthone, 2-methylthioxanthone, isopropylthioxanthone. , And thioxanson-based polymerization initiators such as 2,4-diisopropyloxanson; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2-( p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2-piperonyl-4,6- Bis (trichloromethyl) -s-triazine, 2,4-bis (trichloromethyl) -6-styryl-s-triazine, 2- (naphtho-1-yl) -4,6-bis (trichloromethyl) -s- Triazine, 2- (4-methoxy-naphtho-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2,4-trichloromethyl- (piperonyl) -6-triazine, and 2,4- Triazine-based polymerization initiators such as trichloromethyl (4'-methoxystyryl) -6-triazine; acylphosphine oxide-based polymerization initiators; borate-based polymerization initiators; carbazole-based polymerization initiators; imidazole-based polymerization initiators, etc. Be done. These can be used alone or in combination of two or more.

(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.

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

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

Esters of monobasic acid or polybasic acid and polyalkylene glycol include, for example, polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurylate, polyethylene glycol diolaate, and dipolyethylene glycol methyl 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-terminated urethane prepolymer (UPH) and the boiling point of the solvent.

(Anti-deterioration agent)
The pressure-sensitive adhesive of the present invention may contain one or more kinds of anti-deterioration agents, if necessary. As a result, deterioration of various properties due to long-term use of the adhesive layer can be suppressed. Examples of the anti-alteration agent 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 agents. Of these, the carbodiimide type is preferable from the viewpoint of the hydrolysis inhibitory effect.

A carbodiimide-based hydrolysis inhibitor is a compound having one or more carbodiimide groups in one molecule.
Examples of the monocarbodiimide compound include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, and naphthylcarbodiimide.
The polycarbodiimide compound can be produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst. Here, 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-tolylene diisocyanate, 2,6-tolylene 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-phospholen-1-oxide and phospholen oxides such as these 3-phosphoren isomers.

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

Epoxy-based hydrolysates include, for example, diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, etc. 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. Diglycidyl or polyglycidyl esters of aliphatic or aromatic polyvalent carboxylic acids; resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane, tris- (p-) Diglycidyl ethers or polyglycidyl ethers of polyhydric phenols such as hydroxyphenyl) methane and 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane; N, N-diglycidylaniline, N, N-diglycidyl N-glycidyl derivatives of truidin and amines such as N, N, N', N'-tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl derivatives of aminophenols; triglycidyltris (2-hydroxyethyl) Isocyanurate and triglycidyl isocyanurate; epoxy resins such as orthocresol type epoxy resin and phenol novolac type epoxy resin can be mentioned.

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, based on 100 parts by mass of the hydroxyl-terminated urethane prepolymer (UPH). , Particularly preferably 0.5 to 3 parts by mass.

<Antioxidant>
Examples of the antioxidant include a radical scavenger and a peroxide decomposing agent. 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 hydroxyanisol, 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 distearyl 3,3'-thiodipropionate.

Examples of phosphorus compounds 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-phosphaphenylanthrene-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) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 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-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, particularly preferably 0.1 part by mass, based on 100 parts by mass of the hydroxyl-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 one or more phosphorus compounds in combination. Further, as the antioxidant, it is particularly preferable to use a phenolic compound as a radical scavenger and a phosphorus compound as a peroxide decomposing agent in combination, and these antioxidants and the above-mentioned hydrolysis resistant agent in combination. ..

<UV absorber>
Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, salicylic acid compounds, oxalic acid anilide compounds, cyanoacrylate compounds, and triazine 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 irradiated to the adhesive layer, and the integrated light amount. 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-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-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.

Ionic liquids 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 ions include 1-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-butylpyridinium bis (trifluoromethylsulfonyl) imide, and 1-hexylpyridinium bis (trifluoromethylsulfonyl) imide. 1-octylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4- Methylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide, 1-methylpyridinium bis (perfluoroethylsulfonyl) imide, and 1-methylpyridinium bis (perfluorobutylsulfonyl) ) Imide 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-. Proxammonium 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 appropriately used.

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 an alkali metal ion include lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bispentafluoroethylsulfonylimide, lithiumbisheptafluoropropylsulfonylimide, lithiumbisnonanfluorobutylsulfonylimide, and sodiumbis. Fluorosulfonylimide, sodium bistrifluoromethylsulfonylimide, sodium bispentafluoroethylsulfonylimide, sodium bisheptafluoropropylsulfonylimide, sodium bisnonan fluorobutylsulfonylimide, potassium bisfluorosulfonylimide, potassium bistrifluoromethylsulfonylimide, potassium bis Examples thereof include pentafluoroethyl sulfonyl imide, potassium bisheptafluoropropyl sulfonyl imide, and potassium bisnonan fluorobutyl sulfonyl imide.

Examples of ionic solids 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 Bisnonan fluorobutylsulfonylimide and the like can be mentioned.

Examples of the ionic 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, and 1-hexadecyl-4-methylpyridinium bisnonan fluorobutylsulfonylimide.

Examples of ionic solids containing ammonium ions include lauryltrimethylammonium chloride, tributylmethylbistrifluoromethylsulfonylimide, tributylmethylbispentafluoroethylsulfonylimide, tributylmethylbisheptafluoropropylsulfonylimide, and tributylmethylmubisnonanfluorobutylsulfonylimide. , Octiltributylbistrifluoromethylsulfonylimide, octyltributylbispentafluoroethylsulfonylimide, octyltributylbisheptafluoropropylsulfonylimide, octyltributylmubisnonanfluorobutylsulfonylimide, 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, and fatty acid diethanolamide. Be done.
Examples of anionic low-molecular-weight surfactants include alkyl sulfonates, alkylbenzene sulfonates, and alkyl phosphates.
Examples of the amphoteric low molecular weight 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 alkyldihydroxyethyl betaine.

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-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, and a silicone-based leveling agent. From the viewpoint of suppressing adhesion contamination after re-peeling of the adhesive sheet, an acrylic-based leveling agent or the like is preferable.

The amount of the leveling agent added is not particularly limited, and is preferable with respect to 100 parts by mass of the hydroxyl-terminated urethane prepolymer (UPH) from the viewpoint of suppressing adherent contamination after re-peeling the adhesive sheet and improving the leveling property of the 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, defoamers 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 is one type containing one or more hydroxyl-terminated urethane prepolymers (UPH), one or more polyfunctional isocyanate compounds (I), and three or more (meth) acryloyl groups in one molecule. The above radically polymerizable monomer (MX) is contained as an essential component, and if necessary, one or more optional components are contained. 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 3 to 20 parts by mass, and particularly preferably. Is 5 to 15 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.

From the viewpoint of reducing the adhesive force by irradiation with active energy rays, the amount of one or more radically polymerizable monomers (MX) with respect to 100 parts by mass of one or more hydroxyl-terminated urethane prepolymers (UPH) is preferably 1. It is ~ 100 parts by mass, more preferably 3 to 70 parts by mass, and particularly preferably 5 to 50 parts by mass.

(Adhesive manufacturing method)
The method for producing the pressure-sensitive adhesive of the present invention is not particularly limited.
One or more polyfunctional isocyanate compounds (I), 3 in one molecule, with respect to one or more hydroxyl-terminated urethane prepolymers (UPH) (which may be in the form of a solvent-containing solution) synthesized by the above method. The pressure-sensitive adhesive of the present invention is obtained by adding and mixing one or more radically polymerizable monomers (MX) containing one or more (meth) acryloyl groups and, if necessary, one or more other optional components. Can be manufactured.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the 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 having an pressure-sensitive adhesive layer formed on one side of the 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 sheet is not particularly limited, and examples thereof include a resin sheet, paper, and a metal foil. The base sheet may be a laminated sheet in which any one or more layers are laminated on at least one surface of these base sheets. 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; Amid resin; urethane resin (including foam); a combination 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 adhesive sheet can be produced 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. A known method can be applied as the coating method, and examples thereof include a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.
Next, the coating layer is dried and cured to form an adhesive layer made of a cured product of the adhesive of the present invention. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C. The thickness of the adhesive layer (thickness after drying) varies depending on the 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. An adhesive layer made of a cured product of the adhesive may be formed, and a base sheet may be laminated on the exposed surface of the 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.

[How to use the adhesive sheet]
The method of using the adhesive sheet of the present invention is as follows.
The process of attaching the adhesive sheet of the present invention to the surface of the adherend,
A process of irradiating the adhesive sheet attached to the surface of the adherend with active energy rays such as ultraviolet rays and electron beams to reduce the adhesive force of the adhesive sheet.
It includes a step of peeling the adhesive sheet having reduced adhesive strength from the adherend.

The pressure-sensitive adhesive of the present invention contains a radically polymerizable monomer (MX) and, if necessary, a radical polymerization initiator (R). Therefore, the pressure-sensitive adhesive layer made of the cured product of the pressure-sensitive adhesive of the present invention can be polymerized and cured by irradiation with active energy rays such as ultraviolet rays, and the adhesive strength is effectively reduced after irradiation with respect to before irradiation with active energy rays. be able to.

The pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive of the present invention has an appropriate adhesive strength before irradiation with active energy rays such as ultraviolet rays, has good wettability and spreadability with respect to an adherend, and is adhered. While having re-peelability that can be reattached to the body, it can be attached with an adhesive force that does not easily peel off to the adherend during vacuum suction transfer of the adherend. After irradiation with the active energy ray, the pressure-sensitive adhesive layer made of the cured product of the pressure-sensitive adhesive of the present invention is easily peeled off from the adherend because the adhesive strength is effectively reduced by the polymerization of the radically polymerizable monomer (MX). can do.

In the manufacturing process of a flat panel display, a touch panel display, or the like, in order to improve productivity, it is preferable that the adherend with an adhesive sheet can be conveyed at high speed to a processing unit that performs a necessary process. For example, an automatic high-speed transfer is being studied in which an adherend with an adhesive sheet is adsorbed from the adhesive sheet side using a vacuum suction member, lifted, and transported to a desired location. In this automatic high-speed transfer, it is preferable that the adherend with the adhesive sheet has a relatively high adhesive force in which the adhesive sheet does not peel off from the adherend while being adsorbed by the vacuum suction member. On the other hand, in the adherend with an adhesive sheet that has completed the necessary steps, the adhesive sheet preferably has a relatively low adhesive force so that the adhesive sheet can be peeled off at high speed.
The "adhesive body with adhesive sheet" means a glass substrate, an ITO / glass substrate having an ITO (indium tin oxide) film formed on the glass substrate, and an adhesive sheet on the surface of the adherend such as an optical member. It is a laminated body that has been pasted together.
In the above applications, after the adhesive sheet is attached to the surface of the adherend and the necessary steps are completed, the adhesive sheet attached to the surface of the adherend is subjected to active energy such as ultraviolet rays. The adhesive strength of the adhesive sheet is reduced by irradiating the line, and the adhesive sheet having the reduced adhesive strength can be easily peeled off from the adherend.

The rate of decrease in the adhesive strength of the adhesive layer before and after irradiation with the active energy rays and the rate of decrease in the adhesive strength after irradiation with respect to the active energy rays of the adhesive layer can be appropriately designed according to the application and usage conditions. it can. For applications such as high-speed transport of an adherend with an adhesive sheet using the vacuum suction member as described above, it is preferable to design as follows.

The rate of decrease in the adhesive strength of the adhesive layer after irradiation with respect to the active energy rays before irradiation is not particularly limited, and is preferably 2/3 or less, more preferably 1/2 or less, and particularly preferably 1/3 or less.
The adhesive strength of the adhesive layer before irradiation with the active energy rays is preferably 100 gf / 25 mm or less, more preferably 50 gf / 25 mm or less, and particularly preferably 20 gf / 25 mm or less.
The adhesive strength of the adhesive layer before irradiation with the active energy rays is preferably 8 gf / 25 mm or more, more preferably 10 gf / 25 mm or more, and particularly preferably 15 gf / 25 mm or more.
The adhesive strength of the adhesive layer after irradiation with the active energy rays is preferably 10 gf / 25 mm or less, more preferably less than 8 gf / 25 mm, and particularly preferably less than 5 gf / 25 mm.

As described above, according to the present invention, before irradiation with active energy rays such as ultraviolet rays, the adherend has good wettability and spreadability, and re-peeling that can be reattached to the adherend. Although it has properties, it can be attached to the adherend with an adhesive force that does not easily peel off, and after irradiation with active energy rays, the adhesive force is effectively reduced and the adherend is easily peeled off. It is possible to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer capable of forming a pressure-sensitive adhesive layer.
According to the present invention, before irradiation with active energy rays such as ultraviolet rays, the adherend has good wettability and spreadability, and the adherend has removability that can be reattached. Adhesion that can be attached to the adherend with adhesive strength that does not easily peel off, and after irradiation with active energy rays, the adhesive strength is effectively reduced and can be easily peeled off from the adherend. Sheets can be provided.

[Use]
The 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.
In the present specification, unless otherwise specified, "sheet" shall include "film" and "tape".
Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (OELDs), and 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 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 the glass substrate). It is preferably used as a surface protective sheet for (ITO / glass substrate, etc. on which an (indium tin oxide) film is formed) and an optical member.

Hereinafter, synthesis 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.

[Measurement of molecular weight]
The weight average molecular weight (MXw) and the number average molecular weight (MXn) were measured by gel permeation chromatography (GPC). The measurement conditions are as follows. Both Mw and Mn are polystyrene-equivalent values.
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: SHODEX LF-804 (manufactured by Showa Denko KK) connected in series,
Detector: Differential refractometer,
Solvent: tetrahydrofuran (THF),
Flow velocity: 1 mL / min,
Solvent temperature: 40 ° C,
Sample concentration: 0.2%,
Sample injection volume: 200 μL.

[material]
The materials used are as follows.
<Active hydrogen group-containing compound (HX)>
(HX-1): Kuraray polyol P-2010, polyester polyol, number average molecular weight Mn2000, number of hydroxyl groups 2, manufactured by Kuraray Co., Ltd.,
(HX-2): Sanniks GP-3000, polyether polyol, number average molecular weight Mn3000, number of hydroxyl groups 3, manufactured by Sanyo Chemical Industries, Ltd.,
(HX-3): Sanniks GL-3000, polyether polyol, number average molecular weight Mn3000, number of hydroxyl groups 3, manufactured by Sanyo Chemical Industries, Ltd.,
(HX-4): Excelol 851, polyether polyol, number average molecular weight Mn6700, number of hydroxyl groups 3, manufactured by AGC Inc.,
(HX-5): Sanniks PP-1000, polyether polyol, number average molecular weight Mn1000, number of hydroxyl groups 2, manufactured by Sanyo Chemical Industries, Ltd.,
(HX-6): 1,4-Hexanedimethanol (CHDM).

<Active hydrogen group-containing compound (HY)>
(HY-1): 2-Hydroxyethyl acrylate (HEA).

<Polyisocyanate (N)>
(N-1): Death module H, hexamethylene diisocyanate (HDI), manufactured by Sumika Cobestrolethane,
(N-2): Death module I, isophorone diisocyanate (IPDI), manufactured by Sumika Cobestrolethane,
(N-3): Death module T-80, toluene diisocyanate (TDI), manufactured by Sumika Cobestro Urethane.

<Polyfunctional isocyanate compound (I)>
(I-1): Sumijoule HT, trimethylolpropane adduct of hexamethylene diisocyanate, 75% non-volatile content, manufactured by Sumika Cobestro Urethane Co., Ltd.,
(I-2): Takenate D-110N, trimethylolpropane adduct of xylylene diisocyanate, 75% non-volatile content, manufactured by Mitsui Chemicals, Inc.

<Radical polymerizable monomer (MX)>
(MX-1): MIRAMER M500, dipentaerythritol pentaacrylate, 5 acryloyl groups, 1 hydroxyl group, manufactured by MIWON, Inc.
(MX-2): MIRAMER M600, dipentaerythritol hexaacrylate, 6 acryloyl groups, 0 hydroxyl groups, manufactured by MIWON, Inc.
(MX-3): MIRAMER M300, trimethylolpropane triacrylate, 3 acryloyl groups, 0 hydroxyl groups, manufactured by MIWON, Inc.
(MX-4): MIRAMER M340, pentaerythritol triacrylate, 3 acryloyl groups, 1 hydroxyl group, manufactured by MIWON, Inc.
(MX-5): Sartomer CN925, aliphatic urethane tetraacrylate, 4 acryloyl groups, 0 hydroxyl groups, manufactured by Arkema.

<Photopolymerization Initiator (RL)>
(RL-1): Irgacure TPO, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, manufactured by BASF, Inc.
(RL-2): SB-PI 712, 4-methylbenzophenone, manufactured by Sanyo Trading Co., Ltd.

<Plasticizer (P)>
(P-1): Tributyl Acetylcitrate (ATBC), manufactured by Mitsubishi Chemical Corporation,
(P-2): Monosizer W262, ether ester plasticizer, manufactured by DIC Corporation.

<Antioxidant (O)>
(O-1): Irganox 1010, hindered phenolic antioxidant, manufactured by BASF.

<Antistatic agent (AS)>
(AS-1): IL-P14, ionic liquid, manufactured by Koei Chemical Industry Co., Ltd.

[Synthesis example of a solution of hydroxyl-terminated urethane prepolymer (UPH)]
(Synthesis Example 1)
400 parts of active hydrogen group-containing compound (HX-1) and 600 parts of active hydrogen group-containing compound (HX-2) in a 4-neck flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel. , And 57 parts of polyisocyanate (N-1) were charged. To this, 705 parts of toluene, 0.1 part of dibutyltin dilaurate as a catalyst and 0.04 part of tin 2-ethylhexanoate were added and mixed. The content was gradually heated to 90 ° C. and reacted at 90 ° C. for 2 hours.
Sampling was performed as needed, and after confirming the disappearance of the residual isocyanate group on the infrared absorption (IR) spectrum, the reaction solution was cooled to 30 ° C. to terminate the reaction. As described above, a solution (nonvolatile content: 60%) of the hydroxyl-terminated urethane prepolymer (UPH1) was obtained. The weight average molecular weight Mw of the obtained hydroxyl-terminated urethane prepolymer (UPH1) was 83,000. Table 1 shows the composition and the Mw of the obtained hydroxyl-terminated urethane prepolymer.

(Synthesis Examples 2-7)
In Synthesis Examples 2 to 7, the colorless and transparent hydroxyl group ends are the same as in Synthesis Example 1 except that the type of active hydrogen group-containing compound (HX), the type of polyisocyanate (N), and the compounding ratio thereof are changed. Solutions of urethane prepolymers (UPH-2) to (UPH-7) were obtained. Table 1 shows the compounding composition and the Mw of the obtained hydroxyl-terminated urethane prepolymer in each synthetic example.

(Synthesis Example 11)
Synthesis Example 11 is colorless in the same manner as in Synthesis Example 7 except that an active hydrogen group-containing compound (HY) having one active hydrogen group and one (meth) acryloyl group is added to the charged composition. A solution of a transparent hydroxyl-terminated urethane prepolymer (UPA-1) was obtained. The composition and the Mw of the obtained hydroxyl-terminal urethane prepolymer are shown in Table 1.

[Acrylic resin (AR) synthesis example]
(Synthesis Example 21)
990 parts of n-butyl acrylate, 10 parts of 4-hydroxybutyl acrylate, and 1000 parts of ethyl acetate were placed in a 4-neck flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel and mixed. .. The temperature of the content solution was gradually raised to 90 ° C., and after confirming the reflux of the solvent, 2 parts of azobisisobutyronitrile was added and mixed. After 8 hours, the reaction solution was cooled to terminate the reaction. As described above, a solution of acrylic resin (AR1) (nonvolatile content: 50%) was obtained. The weight average molecular weight Mw of the obtained acrylic resin was 890,000.

[Manufacturing of adhesives and adhesive sheets]
(Example 1)
1 part of polyfunctional isocyanate compound (I-1) and 5 parts of radically polymerizable monomer (MX-1) with respect to 100 parts of the solution of the hydroxyl group-terminated urethane prepolymer (UPH1) obtained in Synthesis Example 1. , 10 parts of radically polymerizable monomer (MX-2), 3 parts of radically polymerizable monomer (MX-3), 1 part of photopolymerization initiator (RL-1), photopolymerization initiator (RL) -2) 1 part, plastic agent (P-1) 30 parts, antioxidant (O-1) 0.1 parts, antistatic agent (AS-1) 0.1 parts, and solvent As a result, 80 parts of ethyl acetate was blended and stirred with a disper to obtain a urethane-based pressure-sensitive adhesive. The blending amount of each material other than the solvent is indicated by the amount of non-volatile content (the same applies to other Examples and Comparative Examples). The compounding composition is shown in Table 2.
As a base sheet, a polyethylene terephthalate sheet having a thickness of 75 μm (double-sided easy-adhesive PET sheet, Cosmo Shine A-4300, manufactured by Toyobo Co., Ltd.) was prepared. The obtained pressure-sensitive adhesive was applied to one side of this base material sheet so that the thickness after drying was 75 μm, and dried at 100 ° C. for 5 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 for 1 week in an atmosphere of 23 ° C.-50% RH, it was subjected to various evaluations.

(Examples 2-35, Comparative Examples 1-3)
In each of Examples 2 to 35 and Comparative Examples 1 to 3, urethane-based or acrylic-based materials were used in the same manner as in Example 1 except that the blending composition of the pressure-sensitive adhesive was changed as shown in Tables 2 to 6. A pressure-sensitive adhesive and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive were manufactured.

[Evaluation items and evaluation methods]
The evaluation items and evaluation methods for the adhesive and the pressure-sensitive adhesive sheet are as follows.
(Wet spreadability)
A test piece having a width of 100 mm and a length of 200 mm was cut out from the obtained adhesive sheet, left for 30 minutes in an atmosphere of 23 ° C. to 50% RH, and then the release sheet was peeled off from the test piece. While holding both ends of the test piece with both hands, the center of the exposed adhesive layer was brought into contact with the glass plate, and then both hands were released. The wettability and spreadability of the adhesive was evaluated by measuring the time required for the entire adhesive layer to adhere to the glass plate by the weight of the test piece. The shorter the time until it comes into close contact with the glass plate, the better the wettability (affinity with the adherend). The evaluation criteria are as follows.
⊚: It takes less than 6 seconds to adhere, which is excellent.
◯: Good contact time is 6 seconds or more and less than 8 seconds.
Δ: The time to adhere is 8 seconds or more and less than 10 seconds, which is practical.
X: It takes 10 seconds or more to adhere, and it is not practical.

(Adhesive strength and removability before ultraviolet (UV) irradiation)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet, left for 30 minutes in an atmosphere of 23 ° C. to 50% RH, and then the release sheet was peeled off from the test piece. Under an atmosphere of 23 ° C.-50% RH, the exposed adhesive layer side of the test piece was attached to a stainless steel (SUS) plate and crimped using a 2 kg roll. After leaving for 24 hours, according to JIS Z0237, using a tensile tester (Tensilon: manufactured by Orientec), the adhesive strength (adhesion before UV irradiation) under the conditions of peeling speed 0.3 m / min and peeling angle 180 °. Force) was measured. It should be noted that the lower the adhesive strength before UV irradiation, the higher the removability and the easier it is to reattach. The evaluation criteria are as follows.
⊚: Less than 20 gf / 25 mm, excellent.
◯: 20 gf / 25 mm or more and less than 50 gf / 25 mm, good.
Δ: 50 gf / 25 mm or more and 100 gf / 25 mm or less, practically possible.
X: Over 100 gf / 25 mm, not practical.

(Vacuum adsorption holding suitability)
A test piece having a width of 70 mm and a length of 100 mm is cut out from the obtained adhesive sheet, contains a general fluorescent lamp that emits light including ultraviolet rays, and is operated under an atmosphere adjusted to 23 ° C.-50% RH. After leaving for a while, the release sheet was peeled off from the test piece. In an atmosphere of 23 ° C.-50% RH, the exposed adhesive layer side of the test piece was attached to a caustic soda glass plate and pressure-bonded using a 2 kg roll. Then, after leaving it for 24 hours under the condition of 60 ° C.-90% RH, it was air-cooled in an atmosphere of 23 ° C.-50% RH for 1 hour. A 0.5 kg weight was attached to the back surface of the glass plate (the surface on which the test piece was not attached). For the test piece / glass plate / weight laminate, hold it by suction from the upper surface (base sheet surface, PET sheet surface) side of the test piece using a vacuum suction member, lift it for 1 minute, and lift a 0.5 kg weight on the back side. It was confirmed whether the glass plate to which was attached was peeled off from the test piece and dropped. The test was carried out 20 times to check the number of drops. It should be noted that the smaller the number of drops, the higher and better the vacuum suction holding suitability, and it is most preferable that there is no drop at all. The evaluation criteria are as follows.
◎: Excellent with no fall.
◯: Good, the number of drops is one.
Δ: The number of drops is 2 to 3 times, which is practical.
X: The number of drops is 4 or more, which is not practical.

(Adhesive strength and removability after ultraviolet (UV) irradiation)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet, left for 30 minutes in an atmosphere of 23 ° C.-50% RH, and then the release sheet was peeled off from the test piece to expose the test piece. The adhesive layer side was attached to a stainless steel (SUS) plate and crimped using a 2 kg roll. After leaving for 24 hours in an atmosphere of 23 ° C.-50% RH, using a high-pressure mercury lamp (peak wavelengths: 254 nm, 365 nm, 405 nm, and 435 nm, output: 120 W), the integrated light intensity is 1000 mJ for the test piece. Ultraviolet (UV) irradiation was performed under the conditions. After air cooling in an atmosphere of 23 ° C.-50% RH for 1 hour, adhesive strength (UV irradiation) was used under the conditions of a peeling speed of 30 m / min and a peeling angle of 180 ° using a tensile tester (Tensilon: manufactured by Orientec). Later adhesive strength) was measured. In addition, the rate of decrease in adhesive strength before UV irradiation was determined. It is preferable that the adhesive strength after UV irradiation and the rate of decrease in the adhesive strength are low because high-speed peeling is possible. The evaluation criteria are as follows.
⊚: Adhesive strength is less than 5 gf / 25 mm, and the rate of decrease in adhesive strength is 2/3 or less, which is excellent.
◯: Adhesive strength is 5 gf / 25 mm or more and less than 8 gf / 25 mm, and the rate of decrease in adhesive strength is 2/3 or less, which is good.
Δ: Adhesive strength is 8 gf / 25 mm or more and 10 gf / 25 mm or less, and the rate of decrease in adhesive strength is 2/3 or less, which is practical.
X: Adhesive strength exceeds 10 gf / 25 mm, or the rate of decrease in adhesive strength exceeds 2/3, which is not practical.

[Evaluation results]
The evaluation results are shown in Tables 2 to 6.
In Examples 1 to 35, it is a reaction product of one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N) (meth). ) Acryloyl group-free hydroxyl group-terminated urethane prepolymer (UPH), polyfunctional isocyanate compound (I), and radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups in one molecule. A urethane-based pressure-sensitive adhesive containing the above was produced. In these examples, a pressure-sensitive adhesive sheet was produced using the obtained pressure-sensitive adhesive.

In all of Examples 1 to 35, the adhesive layer of the obtained adhesive sheet had good wettability and spreadability with respect to the adherend. All of the adhesive sheets obtained in these examples have an appropriate adhesive force before UV irradiation, and have removability that can be reattached to the adherend, while having the removability to the adherend. It can be attached with an adhesive force that does not easily peel off, and the vacuum adsorption holding suitability was good. All of the adhesive sheets obtained in these examples have effectively reduced adhesive strength after UV irradiation and can be easily peeled from the adherend, and are suitable for high-speed peeling. ..

The adhesive sheet obtained in Comparative Example 1 in which an acrylic resin (AR) was used instead of the hydroxyl-terminated urethane prepolymer (UPH) had a very high adhesive strength before UV irradiation, and had a wet spreadability to an adherend. It was defective and had poor removability. The adhesive sheet obtained in Comparative Example 1 still had high adhesive strength even after UV irradiation, and was not suitable for high-speed peeling.

Instead of a hydroxyl group-terminated urethane prepolymer (UPH), one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule, one active hydrogen group in one molecule, and one ( Comparative Example 2 using a hydroxyl group-terminated urethane prepolymer (UPA), which is a reaction product of one or more active hydrogen group-containing compounds (HY) having an acryloyl group and one or more polyisocyanates (N). Then, the obtained adhesive sheet had poor vacuum adsorption holding suitability before UV irradiation. When the adhesive layer absorbs a small amount of UV emitted from the fluorescent lamp, the reaction of the radically polymerizable monomer (MX) is started, the adhesive strength is reduced before UV irradiation, and the vacuum adsorption holding suitability is poor. It is thought that it became.

In Comparative Example 3, a conventional urethane-based adhesive not designed for vacuum adsorption transfer was manufactured. Before UV irradiation, the obtained adhesive sheet had a conventional level of adhesive strength, was low, and had poor vacuum adsorption holding suitability. In Comparative Example 3, since the radically polymerizable monomer (MX) was not used, the decrease in adhesive strength after UV irradiation was small, which was poor.

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

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

[Measurement of molecular weight]
The weight average molecular weight ( Mw ) and the number average molecular weight ( Mn ) were measured by gel permeation chromatography (GPC). The measurement conditions are as follows. Both Mw and Mn are polystyrene-equivalent values.
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: SHODEX LF-804 (manufactured by Showa Denko KK) connected in series,
Detector: Differential refractometer,
Solvent: tetrahydrofuran (THF),
Flow velocity: 1 mL / min,
Solvent temperature: 40 ° C,
Sample concentration: 0.2%,
Sample injection volume: 200 μL.

(Adhesive strength and removability after ultraviolet (UV) irradiation)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the obtained adhesive sheet, left for 30 minutes in an atmosphere of 23 ° C.-50% RH, and then the release sheet was peeled off from the test piece to expose the test piece. The adhesive layer side was attached to a stainless steel (SUS) plate and crimped using a 2 kg roll. After leaving for 24 hours in an atmosphere of 23 ° C.-50% RH, using a high-pressure mercury lamp (peak wavelengths: 254 nm, 365 nm, 405 nm, and 435 nm, output: 120 W), the integrated light intensity is 1000 mJ for the test piece. Ultraviolet (UV) irradiation was performed under the conditions. After air-cooling in an atmosphere of 23 ° C.-50% RH for 1 hour, the adhesive strength is set to a peeling speed of 0.3 m / min and a peeling angle of 180 ° using a tensile tester (Tensilon: manufactured by Orientec). (Adhesive strength after UV irradiation) was measured. In addition, the rate of decrease in adhesive strength before UV irradiation was determined. It is preferable that the adhesive strength after UV irradiation and the rate of decrease in the adhesive strength are low because high-speed peeling is possible. The evaluation criteria are as follows.
⊚: Adhesive strength is less than 5 gf / 25 mm, and the rate of decrease in adhesive strength is 2/3 or less, which is excellent.
◯: Adhesive strength is 5 gf / 25 mm or more and less than 8 gf / 25 mm, and the rate of decrease in adhesive strength is 2/3 or less, which is good.
Δ: Adhesive strength is 8 gf / 25 mm or more and 10 gf / 25 mm or less, and the rate of decrease in adhesive strength is 2/3 or less, which is practical.
X: Adhesive strength exceeds 10 gf / 25 mm, or the rate of decrease in adhesive strength exceeds 2/3, which is not practical.

In the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive of the present invention containing a radical-polymerizable monomer (MX), the pressure-polymerizable monomer (MX) is subjected to irradiation with active energy rays after being attached to an adherend and used. ), The adhesive layer is cured, the adhesive strength of the adhesive layer is reduced, and the adhesive sheet can be easily peeled off from the adherend.
In the present invention, since a trifunctional or higher functional radical polymerizable monomer (MX) containing three or more (meth) acryloyl groups is used, the cross-linking reaction proceeds during the polymerization of the radically polymerizable monomer (MX), resulting in adhesion. The hardening of the layer and the resulting decrease in adhesive strength can be effectively caused. The number of (meth) acryloyl groups contained in the radically polymerizable monomer (MX) is preferably four or more, and more, because the curing of the adhesive layer and the resulting decrease in adhesive strength can be caused more effectively. It is preferably 5 or more. Since the curing of the adhesive layer and the resulting decrease in adhesive strength can be caused more effectively, the amount of the radically polymerizable monomer containing 5 or more (meth) acryloyl groups is the radically polymerizable monomer ( It is preferably 20% by mass or more, more preferably 40% by mass or more, particularly preferably 60% by mass or more, and most preferably 80% by mass or more, based on the total amount of MX).

Claims (12)

A hydroxyl group that is a reaction product of one or more active hydrogen group-containing compounds (HX) having a plurality of active hydrogen groups in one molecule and one or more polyisocyanates (N) and does not contain a (meth) acryloyl group. Terminal urethane prepolymer (UPH) and
A removable pressure-sensitive adhesive containing a polyfunctional isocyanate compound (I).
Further, one molecule contains a radically polymerizable monomer (MX) containing three or more (meth) acryloyl groups.
The pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive is a pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with active energy rays. The adhesive layer has an adhesive strength measured under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 ° using a tensile tester in accordance with JIS Z0237 before and after irradiation with active energy rays. The pressure-sensitive adhesive according to claim 1, wherein the rate of decrease is 2/3 or less. The adhesive layer has an adhesive strength of 100 gf / 25 mm measured under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 ° using a tensile tester in accordance with JIS Z0237 before irradiation with active energy rays. The pressure-sensitive adhesive according to claim 1 or 2, which is as follows. The adhesive layer has an adhesive strength of 10 gf / 25 mm measured under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 ° using a tensile tester in accordance with JIS Z0237 after irradiation with active energy rays. The pressure-sensitive adhesive according to any one of claims 1 to 3, which is as follows. The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the one or more active hydrogen group-containing compounds (HX) contain a trifunctional or higher-functional polyol having three or more hydroxyl groups in one molecule. The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the radically polymerizable monomer (MX) contains 5 or more (meth) acryloyl groups in one molecule. The pressure-sensitive adhesive according to any one of claims 1 to 6, further comprising a plasticizer. The pressure-sensitive adhesive according to any one of claims 1 to 7, further comprising an antistatic agent. The adhesion according to any one of claims 1 to 8, further comprising one or more antioxidants selected from the group consisting of antioxidants, hydrolysis resistant agents, UV absorbers, and light stabilizers. Agent. A pressure-sensitive adhesive sheet comprising a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 9. The adhesive sheet according to claim 10, which is for a surface protection sheet. The process of attaching the adhesive sheet to the surface of the adherend, and
A step of irradiating the adhesive sheet attached to the surface of the adherend with active energy rays to reduce the adhesive force of the adhesive sheet.
The method for using an adhesive sheet according to claim 10 or 11, further comprising a step of peeling the adhesive sheet having reduced adhesive strength from the adherend.

Images