JP6763365B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

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. The adhesives are mainly acrylic adhesives and urethane adhesives. In general, acrylic adhesives have excellent adhesive strength, but when the adhesive sheet is attached to an adherend, air bubbles tend to be easily caught in the adhesion interface. Acrylic adhesives also have poor re-peelability after being attached to the adherend, and tend to cause adherent contamination in which the adhesive remains on the surface of the adherend after re-peeling. On the other hand, the urethane-based adhesive has an appropriate adhesiveness to the adherend, has good adhesion to the adherend, and tends to be excellent in removability.
In the present specification, the "adhesive" is a removable adhesive (removable adhesive), and the "adhesive sheet" is a removable adhesive sheet (removable adhesive sheet).

Flat panel displays such as liquid crystal displays (LCDs) and touch panel displays that combine such flat panel displays and touch panels can be used in electronic devices such as televisions (TVs), personal computers (PCs), mobile phones, and mobile information terminals. Widely used. Urethane-based adhesive sheets are suitably used as surface protective sheets for flat panel displays and touch panel displays, as well as substrates and optical members manufactured or used in these manufacturing processes.

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.

In the production of the pressure-sensitive adhesive sheet, it is preferable that the coating layer cures relatively quickly.
When the coating layer cures relatively quickly, the coating layer and the coating layer and the mechanical stress received during winding and curing of the adhesive sheet obtained after heating and drying as well as hot air during heating and drying of the coating layer The adhesive layer is not easily affected. Therefore, it is possible to produce an adhesive sheet having an adhesive layer having a good surface appearance by suppressing defects such as winding core step marks, citron skin, and curl.
If the coating layer cures relatively quickly, it is easy to apply a thick film of adhesive. By making the adhesive layer thicker, it is possible to form an adhesive layer having excellent cushioning properties and excellent performance (impact resistance, etc.) of protecting adherends such as various optical members from impacts and the like.
If the coating layer cures relatively quickly, the curing period can be shortened.
However, in general, urethane-based pressure-sensitive adhesives tend to be difficult to cure because the molecular weight of the principal component resin is smaller than that of acrylic-based pressure-sensitive adhesives.

In Patent Document 1,
Curing of a urethane-based pressure-sensitive adhesive containing one or more polyols (A) containing a polyol (A1) having three OH groups and a number average molecular weight Mn of 8000 to 20000 and one or more polyfunctional isocyanate compounds (B) An adhesive sheet provided with an adhesive layer made of an object is disclosed (claims 1 and 9).
The pressure-sensitive adhesive sheet described in Patent Document 1 is formed by curing a urethane-based pressure-sensitive adhesive containing a polyol and a polyfunctional isocyanate compound by a so-called one-shot method without using a polyurethane polyol to form a pressure-sensitive adhesive layer.

Patent Document 2 describes 100 parts by weight of a polyurethane resin (A) having a primary hydroxyl group at the terminal and a hydroxyl value of 10 to 40 mgKOH / g, 1 to 20 parts by weight of a polyfunctional isocyanate compound (B), and A urethane-based pressure-sensitive adhesive containing at least 10 to 100 parts by weight of at least one (C) selected from a polyalkylene glycol-based compound, an epoxy-based compound, and a phosphoric acid ester-based compound is disclosed (claim 1).

Patent Document 3 discloses a pressure-sensitive adhesive containing a polyurethane prepolymer and a carboxylic acid ester, wherein the carboxylic acid ester satisfies at least one of the following conditions 1 and 2 (claim). Item 1).
(Condition 1) The carboxylic acid ester contains an ether bond in the molecule.
(Condition 2) The carboxylic acid ester contains 31 or more carbon atoms in one molecule.

Patent Document 4 describes a polyol (A) having two or more OH groups, a polyfunctional isocyanate compound (B), and a catalyst (C) of 0.01 parts by weight or more with respect to 100 parts by weight of the polyol (A). A pressure-sensitive adhesive sheet comprising a cured product of the composition containing the same is disclosed (claims 2, 8 and 9). The pressure-sensitive adhesive sheet described in Patent Document 4 is formed by curing a composition containing a polyol and a polyfunctional isocyanate compound by a so-called one-shot method without using a polyurethane polyol to form a pressure-sensitive adhesive layer.

The codes of the various components in Patent Documents 1 to 4 are the same as those described in the publications, and are irrelevant to the codes of the various components used in the pressure-sensitive adhesive sheet of the present invention.

Japanese Unexamined Patent Publication No. 2014-111701 Japanese Unexamined Patent Publication No. 2015-7226 Japanese Unexamined Patent Publication No. 2015-151429 Japanese Unexamined Patent Publication No. 2014-028878

Patent Document 1 describes that the urethane-based adhesive preferably contains a leveling agent to suppress appearance unevenness due to yuzu skin (paragraph 0073).
The urethane-based adhesive described in Patent Document 1 does not accelerate the curability, and suppresses citron skin by adding a leveling agent. Therefore, it is not possible to realize thick film coating and shortening of the curing period.

According to Patent Document 2, since the component (A) has a primary hydroxyl group at the terminal, the reaction with the polyfunctional isocyanate compound (B) in the pressure-sensitive adhesive proceeds rapidly, and drying and curing does not require time. Is described (paragraph 0036). However, it is preferable that a urethane-based pressure-sensitive adhesive containing any polyurethane polyol can be cured relatively quickly.

Patent Document 3 describes that the above-mentioned pressure-sensitive adhesive can raise the heating temperature after coating on the base material, and that the curing reaction easily proceeds by raising the heating temperature as much as possible (paragraph 0140). However, Patent Document 3 states that "the heating temperature is preferably a temperature exceeding 90 ° C., more preferably 100 ° C. or higher, still more preferably 130 ° C. or higher. The upper limit of the heating temperature is, for example, 150 ° C. or lower. "(Paragraph 0139). Such a heating temperature is a heating temperature generally adopted in the past, and the curing reaction rate cannot be increased more than before.

The one-shot method adopted in Patent Documents 1 and 4 tends to deteriorate the surface appearance of the adhesive layer due to curing shrinkage, and is not suitable for thickening the film.

The present invention has been made in view of the above circumstances, and the coating layer made of a urethane-based adhesive can be cured relatively quickly in the manufacturing process, and an adhesive layer having a good surface appearance can be formed. It is an object of the present invention to provide an adhesive sheet capable of thickening the adhesive layer as needed.

The adhesive sheet of the present invention
A pressure-sensitive adhesive sheet containing a base material sheet and a pressure-sensitive adhesive layer made of a cured product of a urethane-based pressure-sensitive adhesive formed on one surface of the base material sheet.
The urethane adhesive is
Polyurethane polyol (A), which is a copolymerization product of one or more polyols (x) and one or more polyisocyanates (y),
Polyfunctional isocyanate compound (B) and
It contains 0.08 to 0.70 parts by mass of a metal-containing catalyst (MC) with respect to 100 parts by mass of the polyurethane polyol (A).

Generally, the sheet-like material is referred to as "tape", "film", or "sheet" depending on the thickness and width. In the present specification, these are not particularly distinguished, and the term "sheet" is used as a term expressing a concept including these.

In the present specification, the "ethyleneoxy group" is a group represented by the chemical formula "-CH ₂ CH ₂ O-" and may be abbreviated as "EO group". Similarly, ethylene oxide that forms an EO group by a ring-opening reaction may be abbreviated as "EO".

In the present specification, unless otherwise specified, "Mn" is a polystyrene-equivalent number average molecular weight determined by gel permeation chromatography (GPC) measurement, and "Mw" is a polystyrene-equivalent weight average determined by GPC measurement. It is a molecular weight.

According to the present invention, the coating layer made of urethane-based adhesive can be cured relatively quickly in the manufacturing process, an adhesive layer having a good surface appearance can be formed, and the adhesive layer can be thickened as needed. An adhesive sheet that can be filmed 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. It is a schematic cross-sectional view of the pressure-sensitive adhesive sheet of the 3rd Embodiment which concerns on this invention.

The present invention relates to a pressure-sensitive adhesive sheet containing a base material sheet and a pressure-sensitive adhesive layer made of a cured product of a urethane-based pressure-sensitive adhesive.

[Urethane adhesive]
The urethane-based pressure-sensitive adhesive used in the present invention contains one or more polyurethane polyols (A), one or more polyfunctional isocyanate compounds (B), and one or more metal-containing catalysts (MC).

(Polyurethane polyol (A))
The polyurethane polyol (A) is a reaction product obtained by copolymerizing one or more kinds of polyols (x) with one or more kinds of polyisocyanates (y). 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.

<Polyprethane (x)>
The type of the polyol (x) is not particularly limited, and examples thereof include polyester polyols, polyether polyols, polyacrylic polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. Of these, polyester polyols, polyether polyols, and combinations thereof are preferable.

As the polyester polyol, known ones can be used, and examples thereof include compounds (esterified products) obtained by an esterification reaction between one or more polyol components and one or more acid components.

As the polyol component of the raw material, ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-Butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3- Hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, and hexanetriol. And so on.

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, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and their acid anhydrides. And so on.

The number average molecular weight (Mn) of the polyester polyol is not particularly limited, and is preferably 500 to 5,000, more preferably 600 to 4,000, and particularly preferably 800 to 3,000. When Mn is 500 or more, gelation of the polyurethane polyol (A) is effectively suppressed. When Mn is 5,000 or less, the cohesive force of the polyurethane polyol (A) becomes suitable.

A known polyether polyol can be used, and a compound obtained by addition polymerization of one or more oxylan compounds using an active hydrogen-containing compound having two or more active hydrogens in one molecule as an initiator. (Additional polymer).

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; pentafunctional initiators such as diethylenetriamine.

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 "polyoxyalkylene polyol") of an active hydrogen-containing compound is preferable. Of these, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol; trifunctional polyether polyols such as an alkylene oxide adduct of glycerin, and the like are preferable.

The number average molecular weight (Mn) of the polyether polyol is not particularly limited, and is preferably 500 to 5,000, more preferably 600 to 4,000, and particularly preferably 800 to 3,000. When Mn is 500 or more, gelation of the polyurethane polyol (A) is effectively suppressed. When Mn is 5,000 or less, the cohesive force of the polyurethane polyol (A) becomes suitable.

Since the adhesive layer can have a high cohesive force and the occurrence of surface appearance defects such as winding core step marks, twisted skin, and curl of the adhesive layer in the manufacturing process of the adhesive sheet is suppressed, the polyurethane polyol (A) ), It is preferable that one or more kinds of polyols (x) contain one or more kinds of polyester polyols. From the viewpoint of effectively suppressing surface appearance defects, the larger the amount of one or more polyester polyols in the total amount of one or more polyols (x), the better, preferably 50 to 100% by mass, and more preferably 60. ~ 100% by mass, particularly preferably 70 to 100% by mass.

The number of functional groups (number of hydroxyl groups) of one or more types of polyols (x) is arbitrary, and a plurality of types of polyols having different numbers of functional groups may be used in combination, if necessary. In general, the bifunctional polyol has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer. The trifunctional or higher functional polyol has three-dimensional crosslinkability, and can impart appropriate hardness to the adhesive layer. The number of functional groups of one or more polyols (x) can be selected according to the application or the required properties.

In general, urethane-based pressure-sensitive adhesives tend to be harder to cure because the molecular weight of the principal component resin is smaller than that of acrylic-based pressure-sensitive adhesives.
In general, the smaller the number of functional groups of the polyol (x), the lower the crosslinkability of the obtained polyurethane polyol (A) and the lower the curability. Specifically, the obtained polyurethane is obtained when one or more kinds of polyols (x) contain one or more kinds of bifunctional polyols, particularly when one or more kinds of polyols (x) consist only of one or more kinds of bifunctional polyols. The curability of the polyol (A) tends to decrease.
When one or more kinds of polyols (x) contain one or more kinds of bifunctional polyols, the obtained urethane adhesive is hard to cure and has an advantage that a good pot life can be realized, but especially under thick film coating conditions. The initial curability of the coating layer made of urethane-based adhesive may be insufficient.

Details will be described later, but when the urethane-based pressure-sensitive adhesive used in the present invention contains a specific amount of one or more metal-containing catalysts (MC), the type of polyol (x) that is the raw material of the polyurethane polyol (A) Regardless of this, the curability of the coating layer made of urethane-based adhesive can be effectively enhanced while achieving a good pot life.

The present invention is effective when a polyurethane polyol (A) having low curability is used, for example, when a polyurethane polyol (A) obtained by using one or more kinds of bifunctional polyester polyols is used.
The urethane-based adhesive has a good pot life, the adhesive layer can have a high cohesive force, and the surface appearance of the adhesive layer is poor, such as the winding core step marks, the twisted skin, and the curl in the manufacturing process of the adhesive sheet. The curability of the coating layer can be effectively enhanced even under thick film coating conditions. Therefore, one or more polyols (x), which are raw materials for the polyurethane polyol (A), are 1 or more. It is preferable to contain more than one kind of bifunctional polyester polyol, and the amount of one or more kinds of bifunctional polyester polyols in the total amount of one or more kinds of polyester polyols is preferably 20 to 100% by mass, more preferably 30 to 100% by mass. , Particularly preferably 50 to 100% by mass.

<Polyisocyanate (y)>
As the polyisocyanate compound (y), known compounds can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, aromatic 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 and the like can be mentioned.

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

Examples of the aromatic aliphatic polyisocyanate include ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diethylbenzene, 1, , 4-Tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, and methyl-2,4. Examples thereof include −cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4′-methylenebis (cyclohexylisocyanate), and 1,4-bis (isocyanatemethyl) cyclohexane.

In addition, examples of the polyisocyanate include a trimethylolpropane adduct form, a biuret form, and a trimer of the polyisocyanate (the trimer contains an isocyanurate ring) and the like.

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

In the polymerization of the polyurethane polyol (A), one or more polyols (x) and one or more polyisocyanates (y) are 1 with respect to the number of moles of hydroxyl groups (OH) in one or more polyols (x). It is preferable to react at a ratio of the number of moles of isocyanate groups (NCO) in the polyisocyanate (y) of the species or more (NCO / OH functional group ratio) of 0.5 to 0.95.

<Catalyst>
One or more catalysts can be used for the polymerization of the polyurethane polyol (A), if necessary. Known catalysts can be used, and examples thereof include metal-containing catalysts (MC) and other catalysts (non-metal-containing catalysts) (NMC).
When the catalyst used for the polymerization of the polyurethane polyol (A) contains one or more metal-containing catalysts (MC), the one or more metal-containing catalyst (MC) used for the polymerization of the polyurethane polyol (A) is final. It may remain as a component of urethane-based pressure-sensitive adhesive. Examples of the metal-containing catalyst (MC) include tin-based compounds and non-tin-based compounds. Examples of these will be described later.
Examples of other catalysts (non-metal-containing catalysts) (NMCs) include tertiary amine compounds. Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU) and the like.

One kind or two or more kinds of catalysts can be used.
When a plurality of types of polyols (x) having different reactivity are used in combination, gelation or white turbidity of the reaction solution may easily occur in a single catalyst system due to the difference in reactivity. 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 polyols (x) 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 dibutyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate / dibutyltin dilaurate) is not particularly limited, and is preferably more than 0 and less than 1, more preferably 0.2 to 0.6. is there. When the mass ratio is less than 1, the catalytic activity is well-balanced and gelation can be effectively suppressed.

The amount of one or more catalysts used is not particularly limited, and is preferably 0.01 to 1.0 with respect to the total amount of one or more polyols (x) and one or more organic polyisocyanates (y). It is mass%.

<Solvent>
If necessary, one or more kinds of solvents can be used for the polymerization of the polyurethane polyol (A). Known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone.

<Polymerization method>
The polymerization method of the polyurethane polyol (A) is not particularly limited, and known polymerization methods such as a massive polymerization method and a solution polymerization method can be applied.
The polymerization procedure is not particularly limited.
Procedure 1) A procedure in which one or more polyols (x), one or more polyisocyanates (y), one or more catalysts if necessary, and one or more solvents as necessary are collectively charged into a flask. ;
Step 2) One or more polyols (x), one or more catalysts if necessary, and one or more solvents if necessary are charged into a flask, and one or more polyisocyanates (y) are added dropwise thereto. The procedure for adding is mentioned.
Procedure 2) is preferable because the reaction can be easily controlled.

When a catalyst is used, the reaction temperature is preferably less than 100 ° C, more preferably 85 to 95 ° C. When the reaction temperature is less than 100 ° C., the reaction rate, the crosslinked structure and the like can be easily controlled, and the polyurethane polyol (A) having a desired molecular weight can be easily produced.
The reaction temperature when no catalyst is used is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. The reaction time when no catalyst is used is preferably 3 hours or more.

The weight average molecular weight (Mw) of the polyurethane polyol (A) is not particularly limited, and is preferably 10,000 to 500,000, more preferably 10,000 to 500,000 from the viewpoints of adhesive coatability, heat resistance of the pressure-sensitive adhesive layer, removability, and the like. Is 30,000 to 400,000, particularly preferably 50,000 to 350,000. When the Mw of the polyurethane polyol (A) is in an appropriate range, good coatability can be easily obtained.

The hydroxyl value of the polyurethane polyol (A) is not particularly limited, and is preferably 5 to 40 mgKOH / g, more preferably 5 to 35 mgKOH / g. When the hydroxyl value of the polyurethane polyol (A) is 5 mgKOH / g or more, the adhesive strength, heat resistance, moisture heat resistance and other characteristics of the adhesive layer are good. When the hydroxyl value of the polyurethane polyol (A) is 35 mgKOH / g or less, the flexibility of the adhesive layer is good.
The hydroxyl value can be measured by the method described in the section of [Example].

(Polyfunctional isocyanate compound (B))
The polyfunctional isocyanate compound (B) is a curing agent for the polyurethane polyol (A). As the polyfunctional isocyanate compound (B), known compounds can be used, and the compounds exemplified by the polyisocyanate (y) which is the raw material of the polyurethane polyol (A) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate, Aromatic aliphatic polyisocyanates, alicyclic polyisocyanates, and trimetylolpropane adducts / burettes / trimerics thereof) can be used.

The ratio of the number of moles of isocyanate groups (NCO) of one or more polyfunctional isocyanate compounds (B) to the number of moles of hydroxyl groups (OH) of one or more polyurethane polyols (A) (NCO / OH functional group ratio) is It is not particularly limited, and is preferably 1.0 to 4.0, more preferably 1.25 to 3.75, and particularly preferably 1.5 to 3.5. When the NCO / OH functional group ratio is 1.0 or more, the cohesive force of the adhesive layer is good, and when the NCO / OH functional group ratio is 4.0 or less, the adhesive force of the adhesive layer is good.
The blending amount of one or more polyfunctional isocyanate compounds (B) with respect to 100 parts by mass of one or more polyurethane polyols (A) is not particularly limited, preferably 1 to 30 parts by mass, and more preferably 5 to 25 parts by mass. is there. When the blending amount is 1 part by mass or more, the cohesive force of the adhesive layer is good, and when the blending amount is 30 parts by mass or less, the adhesive strength of the adhesive layer is good.

(Plasticizer (P))
The urethane-based pressure-sensitive adhesive used in the present invention may further contain one or more plasticizers (P), if necessary. When the urethane-based adhesive contains one or more plasticizers (P), the wettability of the adhesive layer is improved, and when the adhesive sheet is attached to the adherend, it becomes difficult for air bubbles to get caught in the adhesion interface. The plasticizer (P) is not particularly limited, and an organic acid ester having 10 to 30 carbon atoms is preferable from the viewpoint of compatibility with other components.

Examples of the organic acid ester having 10 to 30 carbon atoms include a monobasic acid or polybasic acid having 6 to 18 carbon atoms and an ester of a branched alcohol having 18 or less carbon atoms, and an unsaturated fatty acid or branched acid having 14 to 18 carbon atoms. Examples thereof include esters with alcohols having a valence of 4 or less, and esters with monobasic acids or polybasic acids having 6 to 18 carbon atoms and polyalkylene glycols.

Examples of the ester of monobasic acid or polybasic acid having 6 to 18 carbon atoms and branched alcohol having 18 or less carbon atoms include isostearyl laurate, isopropyl myristate, isosetyl myristate, octyldodecyl myristate, and isostearyl palmitate. Examples thereof include isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitic acid, and triisocetyl trimellitic acid.

Examples of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms include myristoleic acid, oleic acid, linoleic acid, linolenic acid, isoparmitic acid, and isostearic acid. Examples of the tetravalent or lower alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.

Esters of monobasic acid or polybasic acid having 6 to 18 carbon atoms and polyalkylene glycol include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurylate, polyethylene glycol dioleate, and adipic acid. Examples thereof include dipolyethylene glycol methyl ether.

It is preferable that one or more kinds of plasticizers (P) contain one or more kinds of organic acid esters having one or more ethyleneoxy (EO) groups in one molecule (also referred to as EO group-containing organic acid esters).
Generally, when the adhesive layer is exposed to a high temperature and high humidity environment, it may become cloudy (also referred to as whitening) due to the influence of moisture in the external environment, and the appearance may be deteriorated. Therefore, the adhesive layer preferably has good moisture and heat whitening resistance. By using one or more kinds of EO group-containing organic acid esters, the hydrophilicity of the adhesive layer is improved, and moist heat bleaching can be suppressed. By improving the hydrophilicity of the adhesive layer, the transfer of water between the adhesive layer and the external environment is likely to occur, and even if the moisture invades the adhesive layer from the outside, the moisture is likely to be discharged from the adhesive layer to the external environment. It is considered that the amount of water in the adhesive layer can be kept relatively low.

An index of hydrophilicity includes a water contact angle. By using one or more EO group-containing organic acid esters, for example, it is possible to form an adhesive layer having a water contact angle of 40 to 80 ° after 61000 ms has passed since water was dropped on the surface of the adhesive layer. it can.
The "water contact angle" can be measured by the method described in the section of [Example].

The number of EO groups of the EO group-containing organic acid ester is not particularly limited, and is preferably 1 to 20, more preferably 4 to 14, particularly preferably 4 to 14, from the viewpoint of improving the coatability of the pressure-sensitive adhesive and the moisture-heat whitening resistance of the pressure-sensitive adhesive layer. It is 6 to 8. Examples of the EO group-containing organic acid ester include EO group-containing polyether ester-based plasticizers. Examples of the EO group-containing polyether ester-based plasticizer include polyethylene glycol fatty acid diesters such as polyethylene glycol di-2-ethylhexanoate.

The molecular weight (formula amount or Mn) of the organic acid ester is not particularly limited, and is preferably 300 to 1,000, more preferably 400 to 900, and particularly preferably 500 to 850 from the viewpoint of improving wettability. When the molecular weight is 300 or more, the heat resistance of the pressure-sensitive adhesive layer is good, and when the molecular weight is 1000 or less, the wettability of the pressure-sensitive adhesive is good.

The blending amount of one or more plasticizers (P) with respect to 100 parts by mass of one or more polyurethane polyols (A) is preferably 10 to 70 parts by mass, and more preferably 20 to 50 parts by mass.
When the blending amount is 10 parts by mass or more, the effect of adding the plasticizer (P) (effect of improving wettability) can be effectively exhibited. When the blending amount is 70 parts by mass or less, the amount of the polyurethane polyol (A), which is the main active ingredient of the adhesive, which is originally required, is sufficiently secured, and the performance required as the adhesive is ensured.

(Metal-containing catalyst (MC))
The urethane-based pressure-sensitive adhesive used in the present invention contains one or more metal-containing catalysts (MC).
The timing of adding one or more metal-containing catalysts (MC) is not particularly limited. One or more metal-containing catalysts (MC) may be added at the time of polymerization of one or more polyurethane polyols (A). One or more metal-containing catalysts (MC) are urethane-based adhesives by blending one or more polyurethane polyols (A), one or more polyfunctional isocyanate compounds (B), and if necessary, other optional components. It may be added when preparing the agent.

Examples of the metal-containing catalyst (MC) 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, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, and 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 butoxy-titanium 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 amount of one or more metal-containing catalysts (MC) added to 100 parts by mass of one or more polyurethane polyols (A) is 0.08 to 0.70 parts by mass, preferably 0.09 to 0.65 parts by mass, particularly. It is preferably 0.10 to 0.60 parts by mass.

In general, urethane-based pressure-sensitive adhesives tend to be harder to cure because the molecular weight of the principal component resin is smaller than that of acrylic-based pressure-sensitive adhesives.
In general, the smaller the number of functional groups of the polyol (x), the lower the crosslinkability of the obtained polyurethane polyol (A) and the lower the curability. Specifically, the obtained polyurethane is obtained when one or more kinds of polyols (x) contain one or more kinds of bifunctional polyols, particularly when one or more kinds of polyols (x) consist only of one or more kinds of bifunctional polyols. The curability of the polyol (A) tends to decrease.
When one or more kinds of polyols (x) contain one or more kinds of bifunctional polyols, the obtained urethane adhesive is hard to cure and has an advantage that a good pot life can be realized, but especially under thick film coating conditions. The initial curability of the coating layer made of urethane-based adhesive may be insufficient.
When the amount of one or more metal-containing catalysts (MC) added is 0.08 parts by mass or more, the curability of the coating layer made of urethane adhesive is effective regardless of the type of polyurethane polyol (A). Can be enhanced to. When the amount of one or more metal-containing catalysts (MC) added is 0.70 parts by mass or less, the urethane-based pressure-sensitive adhesive can have a good pot life.

In the manufacturing process of the adhesive sheet, when the coating layer cures relatively quickly, the coating is applied against hot air during heating and drying of the coating layer or mechanical stress received during winding of the adhesive sheet obtained after heating and drying. Layers and adhesive layers are less susceptible. Therefore, it is possible to produce an adhesive sheet having an adhesive layer having a good surface appearance by suppressing the occurrence of defects such as winding core step marks, citron skin, and curl.
If the coating layer cures relatively quickly, it is easy to apply a thick film of adhesive. By making the adhesive layer thicker, it is possible to form an adhesive layer having excellent cushioning properties and excellent performance (impact resistance, etc.) of protecting adherends such as various optical members from impacts and the like.
If the coating layer cures relatively quickly, the curing period can be shortened.

The urethane-based pressure-sensitive adhesive used in the present invention contains one or more other catalysts (non-metal-containing catalyst) (NMC) in accordance with one or more metal-containing catalysts (MC), if necessary. Can be done. Examples of other catalysts (non-metal-containing catalysts) (NMCs) include tertiary amine compounds. Examples of the tertiary amine compound are the same as the catalyst used in the polymerization of the polyurethane polyol (A).

(solvent)
The urethane-based pressure-sensitive adhesive used in 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.

(Anti-deterioration agent)
The urethane-based pressure-sensitive adhesive used in the present invention may contain one or more kinds of deterioration inhibitor, 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 high temperature and high humidity environment to generate a carboxy group, one or more types of hydrolysis resistant agents can be used to block the carboxy group.
Examples of the hydrolysis resistant agent include carbodiimide-based, isocyanate-based, oxazoline-based, and epoxy-based. 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, as the diisocyanate, 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, 4, Examples thereof include 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 isocyanate-based hydrolysis inhibitor include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenedi isocyanate, p-phenylenedi isocyanate, 4,4'-diphenylmethane diisocyanate, and 2,4'-diphenylmethane diisocyanate. , 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylenediocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, 3,3'-dichloro-4,4' -Bifenylene diisocyanate, 1,5-naphthalenedylene diisocyanate, 1,5-tetrahydronaphthalenedenedis isocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1, 4-Cyclohexamethylene diisocyanate, xylylene diisocyanate, tetramethylxamethylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanis, isophorone diisocyanate, 4,4'-dicyclohexamethylene diisocyanate, and 3,3'-dimethyl-4,4'- Examples thereof include dicyclohexylmethane diisocyanate.

Examples of the oxazoline-based hydrolysis inhibitor include 2,2'-o-phenylenebis (2-oxazoline), 2,2'-m-phenylenebis (2-oxazoline), and 2,2'-p-phenylenebis (2). -Oxazoline), 2,2'-p-phenylenebis (4-methyl-2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline), 2,2'-p-phenylene Bis (4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylene bis (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 hydrolysates include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, and tri. Polyglycidyl ethers of aliphatic polyols such as methylolpropane; polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol; aliphatics such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, and sebacic acid. Or diglycidyl ester or polyglycidyl ester of aromatic polyvalent carboxylic acid; resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane, tris- (p-hydroxyphenyl) ) Diglycidyl ethers or polyglycidyl ethers of polyvalent phenols such as methane and 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane; N, N-diglycidylaniline, N, N-diglycidyl toluidin, And N-glycidyl derivatives of amines such as N, N, N', N'-tetraglycidyl-bis- (p-aminophenyl) methane; triglycidyl derivatives of aminoferrs; 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 one or more hydrolysis resistant agents added is not particularly limited, and is preferably 0.1 to 5.0 parts by mass, more preferably 0.2 to 4. by mass, based on 100 parts by mass of the polyurethane polyol (A). It is 5 parts by mass, particularly preferably 0.5 to 3.0 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 phenolic compounds 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, 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] Methan, bis [3,3'-bis- (4'-hydroxy-3'-t-butylphenyl) ) Butyric acid] glycol ester, 1,3,5-tris (3', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) Trion, tocophenol and the like can be mentioned.

Phenyl antioxidants include triphenylphosphite, diphenylisodecylphosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenylditridecyl) phosphite, 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 one or more kinds of antioxidants, it is possible to prevent thermal deterioration of the polyurethane polyol (A) and effectively suppress bleeding out of the plasticizer (P) from the adhesive layer.
The amount of one or more antioxidants added is not particularly limited, and is preferably 0.01 to 2.0 parts by mass, more preferably 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the polyurethane polyol (A). It is by mass, particularly preferably 0.2 to 1.0 parts by mass.

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

(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 one or more ultraviolet absorbers added is not particularly limited, and is preferably 0.01 to 3.0 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the polyurethane polyol (A). It is by mass, particularly preferably 0.2 to 2.0 parts by mass.

(Light stabilizer)
Examples of the light stabilizer include hindered amine compounds and hindered piperidine compounds. The amount of one or more light stabilizers added is not particularly limited, and is preferably 0.01 to 2.0 parts by mass, more preferably 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the polyurethane polyol (A). It is by mass, particularly preferably 0.2 to 1.0 parts by mass.

(Leveling agent)
The urethane-based pressure-sensitive adhesive used in the present invention may contain one or more leveling agents, if necessary. By adding one or more leveling agents to the urethane adhesive, 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 silicon-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 weight average molecular weight (Mw) of the leveling agent is not particularly limited, and is preferably 500 to 20,000, more preferably 1,000 to 15,000, and particularly preferably 2,000 to 10,000. When Mw is 500 or more, the amount of vaporization from the coating layer is sufficiently small when the coating layer is heated and dried, and contamination of the surroundings is suppressed. When Mw is 20,000 or less, the effect of improving the leveling property of the adhesive layer is effectively exhibited.

The amount of one or more leveling agents added is not particularly limited, and is preferable with respect to 100 parts by mass of the polyurethane polyol (A) from the viewpoint of suppressing adherent contamination after re-peeling the pressure-sensitive adhesive sheet and improving the leveling property of the pressure-sensitive adhesive layer. Is 0.001 to 2.0 parts by mass, more preferably 0.01 to 1.5 parts by mass, and particularly preferably 0.1 to 1.0 parts by mass.

(Other optional ingredients)
The urethane-based pressure-sensitive adhesive used in the present invention is added with one or more other types such as an antistatic agent, a silane coupling agent, a coloring agent, an antifoaming agent, a wetting agent, a weather-resistant stabilizer, and a softening agent, if necessary. Can include agents.

[Adhesive layer]
The adhesive layer is made of a cured product of a urethane-based adhesive.
Probe tack of the adhesive layer is preferably 0.01~0.30N / cm ^2, more preferably 0.02~0.25N / cm ^2, particularly 0.05~0.2N / cm ^2. The adhesive layer having the probe tack in such a range has suitable adhesive strength and can have good adhesiveness to the adherend.
For example, by adjusting the type and amount of the polyfunctional isocyanate compound (B) to be blended with the polyurethane polyol (A), the adhesive strength of the pressure-sensitive adhesive layer can be adjusted within a preferable range. If the types of the polyurethane polyol (A) and the polyfunctional isocyanate compound (B) are the same, the probe tack tends to decrease as the amount of the polyfunctional isocyanate compound (B) increases.
In this specification, the probe tack shall be measured by the method described in the section of [Example].

The preferable shearing force of the adhesive layer is as follows.
The shearing force when the adhesive layer side of the adhesive sheet is attached to the glass plate with a contact area of 10 × 20 mm ² and the adhesive sheet is peeled from the glass plate in the 180 ° direction at a peeling speed of 50 mm / min is preferably 5. It is ~ 25 N / cm ² , more preferably 6 to 20 N / cm ² , and particularly preferably 7 to 15 N / cm ² .
When the shearing force is 5 N / cm ² or more, the adhesive layer does not easily stretch, the adhesive sheet has good adhesiveness when attached to the adherend, and the position of the adhesive sheet when attached to the adherend. Easy to adjust and re-paste. When the shearing force is 25 N / cm ² or less, it is possible to prevent the adhesive layer from being stretched too much and causing the adhesive sheet to be displaced after being attached to the adherend.

For example, by adjusting the type and amount of the polyfunctional isocyanate compound (B) to be blended with the polyurethane polyol (A) and the type and amount of the plasticizer (P), the shearing force of the adhesive layer can be adjusted within a preferable range. can do. If the types of the polyurethane polyol (A) and the polyfunctional isocyanate compound (B) are the same, the shearing force tends to increase as the amount of the polyfunctional isocyanate compound (B) increases. If the types of the polyurethane polyol (A) and the polyfunctional isocyanate compound (B) are the same, the shearing force tends to decrease by adding the plasticizer (P). If the types of the plasticizer (P) are the same, the shearing force tends to decrease as the amount of the plasticizer (P) increases.
In addition, in this specification, a shearing force shall be measured by the method described in the section of [Example].

The urethane-based pressure-sensitive adhesive used in the present invention can be suitably used for both thin-film coating and thick-film coating, and has a higher degree of freedom in designing the thickness of the adhesive layer than before. The thickness of the pressure-sensitive adhesive layer can be appropriately designed depending on the use of the pressure-sensitive adhesive sheet, and may be a conventional level (5 to 30 μm) or a thick film level of 30 μm or more, which was difficult in the past. By thickening the adhesive layer, it is possible to form an adhesive layer having excellent impact resistance and an excellent function of protecting the adherend from impact and the like. The upper limit of the thickness of the adhesive layer is not particularly limited, and is about 200 μm because an adhesive layer having good surface smoothness can be formed. From the viewpoint of improving impact resistance and surface smoothness, the thickness of the adhesive layer is preferably 30 to 200 μm, more preferably 40 to 150 μm, and particularly preferably 50 to 150 μm. In the present specification, the "thickness of the adhesive layer" is the thickness after drying unless otherwise specified.

[Embodiment of 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 a urethane-based pressure-sensitive adhesive. 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 (also referred to as a release liner). The release sheet is peeled off when the adhesive sheet is attached to the adherend.

1 to 3 are schematic cross-sectional views of the pressure-sensitive adhesive sheet according to the first to third embodiments of the present invention. In FIGS. 1 to 3, reference numerals 10X, 10Y, and 10Z are adhesive sheets, reference numeral 11 is a base material sheet, reference numeral 12 is an adhesive layer, and reference numerals 13X, 13Y, and 13Z are release sheets. The adhesive sheets 10X, 10Y, and 10Z are single-sided adhesive sheets in which an adhesive layer is formed on one side of the base material sheet. In FIGS. 1 to 3, the same components are designated by the same reference numerals.

(Base sheet)
The base sheet 11 may be a single-layer sheet composed of the sheet body 11A, or may be a laminated sheet in which any one or more layers are laminated on at least one surface of the sheet body 11A. From the viewpoint of antistatic of the adhesive sheets 10X, 10Y and 10Z, the base sheet 11 preferably includes the sheet body 11A and the antistatic layer 11B formed on the non-forming side surface of the adhesive layer 12. When the base sheet 11 includes the antistatic layer 11B, it is possible to suppress the generation of static electricity that affects the electronic device.

The sheet body 11A is not particularly limited, and examples thereof include a resin sheet, paper, and a metal foil, and a resin sheet is preferable.
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-based resins; urethane-based resins (including foams); combinations thereof and the like can be mentioned. As the sheet body 11A, a PET sheet or the like is preferable.
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.

Since the adhesive layer 12 having excellent surface smoothness can be formed, the arithmetic mean roughness (Ra) of the sheet body 11A is preferably 0.7 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.2 μm or less. is there.
The sheet body 11A preferably has high transparency, and the haze of the sheet body 11A is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less.

The antistatic layer 11B contains one or more antistatic agents (AS). As the antistatic agent (AS), known ones can be used, and examples thereof include a surfactant (SF) and a conductive polymer (EP).

Surfactants (SF) used as antistatic agents (AS) are classified into low molecular weight surfactants and high molecular weight surfactants. In each type, there are nonionic, anionic, cationic, and amphoteric types.

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 cationic low molecular weight surfactant include tetraalkylammonium salts and trialkylbenzylammonium salts.
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 cationic polymer surfactant include a quaternary ammonium base-containing acrylate polymer 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.

Conductive polymers (EP) used as antistatic agents (AS) include polyacetylene, polyaniline, polythiophene, polypyrrole, polyphenylene sulfide, poly (1,6-heptadiyne), polybiphenylene (polyparaphenylene), and polyparaphenylene sulfide. , Polyphenylacetylene, poly (2,5-thienylene), derivatives thereof and the like.

As the antistatic agent (AS), a conductive polymer (EP) is preferable.
Generally, the adhesive sheet may become cloudy (whiten) when exposed to a high temperature and high humidity environment. Since the conductive polymer (EP) has lower hydrophilicity than the surfactant (SF), the antistatic layer 11B can be formed by using one or more kinds of conductive polymers (EP) as the antistatic agent (AS). It is considered that it is less affected by humidity and can suppress moist heat bleaching.
The water contact angle can be mentioned as an index of hydrophilicity. The antistatic layer 11B preferably has a water contact angle of 40 to 110 °, more preferably 60 to 110 °, particularly preferably 70 to 110 ° after 1000 ms has passed since water was dropped on the surface of the antistatic layer. Is.

As shown in FIGS. 1 to 3, the release sheets 13X, 13Y, and 13Z include a sheet body 13A and a release agent layer 13L formed on the surface of the adhesive layer 12 side. As shown in FIGS. 2 and 3, from the viewpoint of antistatic of the pressure-sensitive adhesive sheet, the release sheets 13Y and 13Z can further include an antistatic layer 13B formed on the surface opposite to the pressure-sensitive adhesive layer 12. As shown in FIG. 3, from the viewpoint of improving the antistatic property of the pressure-sensitive adhesive sheet, the release sheet 13Z can further include the antistatic layer 13B between the sheet body 13A and the release agent layer 13L.
Examples of the sheet body 13A include a resin sheet and paper.
The release agent layer 13L contains one or more types of release agents such as silicone resin.
One or more antistatic agents used for the antistatic layer 13B are the same as the antistatic layer 11B of the base sheet 11 described above. From the viewpoint of improving the moisture resistance and heat whitening property, the antistatic layer 13B preferably contains one or more kinds of conductive polymers (EP). Like the antistatic layer 11B, the antistatic layer 13B preferably has a water contact angle of 40 to 110 ° after 1000 ms has passed since water was dropped on the surface of the antistatic layer.

The adhesive sheets 10X, 10Y, and 10Z can be produced by a known method.
First, a urethane-based pressure-sensitive adhesive is applied to the surface of the base material sheet 11 to form a coating layer made of the urethane-based pressure-sensitive adhesive. 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 containing a cured product of a urethane-based adhesive. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C.
Next, if necessary, the release sheets 13X and 13Y are attached to the exposed surface of the adhesive layer 12 by a known method.
As described above, the adhesive sheets 10X, 10Y and 10Z can be manufactured.
Contrary to the above method, a urethane-based adhesive is applied to the surfaces of 13X, 13Y, and 13Z to form a coating layer made of urethane-based adhesive, and then the coating layer is dried and cured to obtain urethane-based adhesive. The pressure-sensitive adhesive layer 12 containing the cured product of the agent may be formed, and finally the base material sheet 11 may be laminated on the exposed surface of the pressure-sensitive adhesive layer 12.

The manufactured 10X, 10Y, and 10Z can preferably be wound around a winding core to form an adhesive sheet roll. Further, since an uncured product may remain in the adhesive layer 12 at this point, it is preferable to cure the adhesive sheet roll for a certain period of time.

(Use)
The pressure-sensitive adhesive sheet of the present invention can be used in the form of tapes, labels, stickers 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.
Flat panel displays such as liquid crystal displays (LCDs) and touch panel displays that combine such flat panel displays and touch panels can be used in electronic devices such as televisions (TVs), personal computers (PCs), mobile phones, and mobile information terminals. Widely used.
The adhesive sheet of the present invention is suitably used as a surface protective sheet for flat panel displays and touch panel displays, as well as substrates and optical members manufactured or used in these manufacturing processes.

As described above, according to the present invention, the coating layer made of urethane-based adhesive can be cured relatively quickly in the manufacturing process, and an adhesive layer having a good surface appearance can be formed, which is necessary. A pressure-sensitive adhesive sheet capable of thickening the pressure-sensitive adhesive layer can be provided accordingly.

In the manufacturing process of the adhesive sheet, when the coating layer cures relatively quickly, the coating is applied against hot air during heating and drying of the coating layer or mechanical stress received during winding of the adhesive sheet obtained after heating and drying. Layers and adhesive layers are less susceptible. Therefore, it is possible to manufacture an adhesive sheet having an adhesive layer having a good surface appearance by suppressing the occurrence of defects such as winding core step marks, citron skin, and curl of the adhesive layer.
If the coating layer cures relatively quickly, it is easy to apply a thick film of adhesive. By making the adhesive layer thicker, it is possible to form an adhesive layer having excellent cushioning properties and excellent performance (impact resistance, etc.) of protecting adherends such as various optical members from impacts and the like.
If the coating layer cures relatively quickly, the curing period can be shortened.

The present invention is particularly effective when the curability of the polyurethane polyol (A) is low. The present invention is effective, for example, when one or more polyols (x), which are raw materials for the polyurethane polyol (A), contain one or more bifunctional polyols.

When the urethane-based pressure-sensitive adhesive contains one or more plasticizers (P) and one or more plasticizers (P) contain one or more EO group-containing organic acid esters, the hydrophilicity of the pressure-sensitive adhesive layer is improved. , Moisture-resistant heat whitening of the adhesive layer can be improved.

When the base sheet of the pressure-sensitive adhesive sheet contains an antistatic layer, the pressure-sensitive adhesive sheet has antistatic properties and is preferable. Further, when the antistatic layer contains one or more kinds of conductive polymers (EP), the antistatic layer is not easily affected by humidity, and the moisture-resistant heat whitening of the adhesive layer can be improved.

Hereinafter, synthesis examples, examples according to the present invention, and comparative examples will be described.
[Evaluation items and evaluation methods for various physical properties]
(Weight average molecular weight (Mw))
The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC) method. The measurement conditions were as follows. Mw is a polystyrene-equivalent value.
<Measurement conditions>
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: TOSOH TSK-GEL GMHXL (manufactured by Tosoh) connected in series,
Solvent: tetrahydrofuran,
Flow velocity: 0.5 ml / min,
Solvent temperature: 40 ° C,
Sample concentration: 0.1% by mass,
Sample injection volume: 100 μl.

(viscosity)
The viscosity was measured under the following conditions in accordance with JISZ8803.
Equipment: B-type viscometer TVB10M (Toki Sangyo Co., Ltd.),
Rotor: No. 3,
Rotation speed: 12 rpm,
Measurement temperature: 25 ° C.

(Hydroxy group value)
The hydroxyl value was measured by a neutralization titration method according to JIS K0070.
First, 25 g of acetic anhydride was placed in a 100 ml flask, and pyridine was added thereto to make a total volume of 100 ml. The contents were shaken well to prepare an acetylation reagent. The resulting acetylation reagent was stored in a brown bottle away from contact with moisture, carbon dioxide, and acid vapors.
Next, the sample was weighed into a flat-bottomed flask, 5 ml of the above acetylation reagent was added to it using a pipette, and a small funnel was placed in the mouth of the flask. The bottom of the flask (a portion having a height of about 1 cm from the bottom) was immersed in a glycerin bath having a temperature of 95 to 100 ° C. and heated. At this time, in order to prevent the temperature of the neck of the flask from rising due to the heat of the glycerin bath, a donut-shaped cardboard having a round hole in the center was placed on the base of the neck of the flask. One hour after the start of heating in the glycerin bath, the flask was removed from the glycerin bath and allowed to cool. Then, 1 ml of water was supplied into the flask through the funnel, and the flask was shaken to decompose acetic anhydride.
In order to complete the decomposition of acetic anhydride, the bottom of the flask was heated again in the glycerin bath for 10 minutes in the same manner as described above, and then the flask was removed from the glycerin bath and allowed to cool. Then, 5 ml of ethanol was supplied into the flask through the funnel. At this time, the entire inner wall of the funnel and the entire inner wall of the flask were washed with ethanol.
Next, several drops of a phenolphthalein solution was added to the flask as an indicator, and titration was performed using a 0.5 mol / l potassium hydroxide ethanol solution. The end point was when the indicator had a light red color for about 30 seconds.
Separately, a blank test was conducted in which the same operation as above was performed without placing the sample in the flask.
The hydroxyl value of the polyurethane polyol (A) (solid content) was calculated by the following formula (1).
A = ((BC) × f × 28.05 / S) / (nonvolatile content concentration / 100) + D ... (1)
(However, in the above formula (1), A: hydroxyl value (mgKOH / g), B: amount of 0.5 mol / l potassium hydroxide ethanol solution used in the blank test (ml), C: 0 used for titration. .Amount of 5 mol / l potassium hydroxide ethanol solution (ml), f: Factor (concentration correction coefficient) of 0.5 mol / l potassium hydroxide ethanol solution, S: Mass of sample (g), D: Acid value (mgKOH) / G).)
In the present specification, the hydroxyl value may be abbreviated as "OH value".

[Base sheet]
The base sheet used is as follows.
<Base sheet (SH-1)>
A polyethylene terephthalate (PET) sheet (ester film E5100, one surface with corona treatment, manufactured by Toyobo) having a thickness of 50 μm was prepared as the sheet body, and this was used as it was as a base sheet (SH-1).

<Base sheet (SH-2)>
A dispersion liquid (Enocoat BP105, manufactured by Kaken Sangyo Co., Ltd.) containing conductive polythiophene was prepared as the conductive polymer (EP-1). This conductive polythiophene dispersion was diluted with propanol to obtain an antistatic coating agent (ASC-1) (nonvolatile content (NV) 1% by mass). A base sheet (SH-1) was prepared as the sheet body. The above antistatic coating agent (ASC-1) is applied to the corona-treated surface of the sheet body by the bar coater method, dried in an oven at 80 ° C. for 3 minutes, and an antistatic layer having a thickness of 0.5 μm. Was formed. As described above, a base sheet (SH-2) with an antistatic layer was obtained.

<Base sheet (SH-3)>
Polyoxyethylene sorbitan monolaurate (nonionic surfactant) was prepared as a surfactant (SF-1), and this was used as it was as an antistatic coating agent (ASC-2). A base sheet (SH-3) with an antistatic layer was obtained by the same method as in the production of the base sheet (SH-2) except that this antistatic coating agent was used.

[material]
The materials used in Synthesis Examples, Examples, and Comparative Examples are as follows.
<Polyprethane (x)>
(X-1): Kuraray polyol P1010 (polyester diol, OH value 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.),
(X-2) F2010: Kuraray polyol F2010 (polyester triol, OH value 84, molecular weight 2,000, manufactured by Kuraray Co., Ltd.),
(X-3) PP2000: Sanniks PP-2000 (polyetherdiol, OH value 56, molecular weight 2,000, manufactured by Sanyo Chemical Industries, Ltd.),
(X-4) G3000B: ADEKA polyol G3000B (polyether triol, OH value 56, molecular weight 3,000, manufactured by ADEKA Corporation).

<Polyisocyanate (y)>
(Y-1): Death module H (hexamethylene diisocyanate, manufactured by Sumika Cobestrolethane Co., Ltd.).

<Metal-containing catalyst (MC)>
(MC-1): Di-n-butyltin dilaurate,
(MC-2): Bismuth neodecanoate.
<Other catalysts (non-metal-containing catalysts) (NMC)>
(NMC-1) 1,8-diazabicyclo [5.4.0] -7-undecene.

<Polyfunctional isocyanate compound (B)>
(B-1): Coronate HX (isocyanurate form of hexamethylene diisocyanate, non-volatile content (NV) 100% by mass, NCO group amount 21 mol%, manufactured by Tosoh Corporation).

<Plasticizer (P)>
(P-1): Monosizar W262 (polyether ester plasticizer, containing EO group, non-volatile content (NV) 100% by mass, molecular weight 556, manufactured by DIC Corporation,
(P-2): Polysizer W320 (adipic acid-based polyester plasticizer, EO group-free, non-volatile content (NV) 100% by mass, molecular weight 1000, manufactured by DIC Corporation).

<Additive (R)>
(R-1): Acetylacetone.

[Synthesis example of polyurethane polyol (A) solution]
(Synthesis Example 1)
In a 4-neck flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel, 100 parts by mass of polyol (x-1) and 15.5 parts of polyisocyanate (y-1) under a nitrogen atmosphere. A parts by mass, 77 parts by mass of toluene, and 0.02 parts by mass of a metal-containing catalyst (MC-1) were charged. Gradually raise the temperature of the flask and at about 90 ° C. 2
A time reaction was performed. Then, the reaction was continued while confirming whether or not the residual isocyanate group disappeared in the infrared absorption (IR) spectrum, and after confirming the disappearance, the flask was immediately cooled to terminate the reaction. Finally, toluene was added so that the non-volatile content (NV) was 60% by mass.
As described above, a solution of polyurethane polyol (A-1) was obtained. The viscosity of this solution was 3,000 mPa · s. The obtained polyurethane polyol (A-1) had a hydroxyl value of 7.6 mgKOH / g and a weight average molecular weight (Mw) of 55,000.
Table 1 shows the compounding composition and the evaluation results of the physical properties of the obtained solution of the polyurethane polyol (A-1). In Table 1, 2f indicates bifunctionality and 3f indicates trifunctionality. In Table 1, the unit of the blending amount of each material is [parts by mass]. Table 1 also shows the amount (unit: parts by mass) of the metal-containing catalyst (MC) with respect to 100 parts by mass of the polyurethane polyol (A) in the solution.

(Synthesis Examples 2-5)
In Synthesis Examples 2 to 5, solutions of polyurethane polyols (A-2) to (A-5) were obtained in the same manner as in Synthesis Example 1 except that the composition of the raw materials was changed as shown in Table 1. Table 1 shows the results of physical property evaluation of the obtained polyurethane polyol solution in each synthesis example.

[Example 1]
Various materials were added to the solution of the polyurethane polyol (A-1) obtained in Synthesis Example 1. The amount of polyurethane polyol (A-1) in the solution was 100 parts by mass. On the other hand, the polyfunctional isocyanate compound (B-1) was 5.4 parts by mass, and the toluene solution of the metal-containing catalyst (MC-1) (nonvolatile content (NV) 2.5% by mass) was 0 in terms of solid content. .150 parts by mass, 6 parts by mass of the additive (R-1), and 5 parts by mass of ethyl acetate as a solvent were blended. A urethane-based adhesive was obtained by stirring these materials with a dispar. The obtained urethane adhesive was immediately used for evaluation of pot life. Further, the obtained urethane-based pressure-sensitive adhesive was used for evaluation of thick film coatability.
As a base sheet, a base sheet (SH-2) with an antistatic layer was prepared. The non-formed surface of the antistatic layer of the base sheet was coated with the obtained urethane-based adhesive using a doctor blade so that the thickness after drying was 50 μm. The formed coating layer was dried at 120 ° C. for 4 minutes to form an adhesive layer. A release sheet having a thickness of 25 μm (250010BD, manufactured by Fujimori Kogyo Co., Ltd.) was attached onto this adhesive layer to obtain an adhesive sheet. The obtained adhesive sheet was cured under the condition of 23 ° C.-50% RH for 1 week and then subjected to other evaluations.

[Examples 2 to 12, Comparative Examples 1 to 5]
In each of Examples 2 to 12 and Comparative Examples 1 to 5, urethane was used in the same manner as in Example 1 except that the composition of the urethane adhesive and the base sheet used were changed to those shown in Table 2. Adhesives and adhesive sheets were obtained and evaluated.
In Table 2, the unit of the blending amount of each material is [part by mass]. The blending amount of the metal-containing catalyst (MC) and the other catalyst (NMC) is the amount of the catalyst newly added in Examples or Comparative Examples. The total amount of the metal-containing catalyst (MC) is the metal-containing catalyst (MC) contained in the solution of the polyurethane polyol (A) obtained in the synthetic example and the metal-containing catalyst (MC) newly added in the example or comparative example. Is the total amount of. Regarding the polyfunctional isocyanate compound (B), the ratio of the number of moles of the isocyanate group (NCO) in the polyfunctional isocyanate compound (B) to the number of moles of the hydroxyl group (OH) in the polyurethane polyol (A) (NCO /). The OH functional group ratio) is also shown.

[Evaluation items and evaluation methods for adhesives and adhesive sheets]
The evaluation items and evaluation methods for urethane-based adhesives and pressure-sensitive adhesive sheets are as follows. (Pot life)
Immediately after manufacturing, the obtained urethane adhesive is placed in a glass bottle with a lid, the glass bottle is placed in a constant temperature water bath at 25 ° C., and the viscosities of the urethane adhesive are measured 1 hour and 12 hours after the start of charging, respectively. did. The rate of increase in viscosity after 12 hours with respect to 1 hour (viscosity after 12 hours / viscosity after 1 hour [times]) was determined. The evaluation criteria are as follows.
<Evaluation criteria>
◯: Viscosity increase rate is less than double (excellent),
Δ: Viscosity increase rate is 2 times or more and less than 3 times (good),
X: Viscosity increase rate is 3 times or more (there is a problem in practical use).

(Thick film coatability)
As a base sheet, a polyethylene terephthalate (PET) sheet (Lumirror T-60, manufactured by Toray Industries, Inc.) having a width of 430 mm and a thickness of 100 μm was prepared. Adhesive sheets were manufactured by a roll-to-roll process using a test manufacturing device (comma coater: registered trademark).
The transport speed of the base sheet was 1.0 m / min. The obtained urethane adhesive was applied to one side of the base sheet with a width of 400 mm so that the thickness after drying was 150 μm to form a coating layer. The sheet was then passed through a 4 m long oven set at 130 ° C. to dry and cure the coating layer. Next, a release sheet (250010BD, manufactured by Fujimori Kogyo Co., Ltd.) having a width of 430 mm and a thickness of 25 μm was attached onto the formed adhesive layer. Next, the obtained adhesive sheet was wound around a winding core (6 inch ABS core) to a length of 100 m. The obtained adhesive sheet roll was cured under the condition of 23 ° C.-50% RH for 1 week.
Before curing, a test piece having a width of 400 mm and a length of 500 mm was cut out from the obtained adhesive sheet roll at a position 1 m long from the end on the winding end side (outside) of the adhesive sheet, and the following evaluation was performed. It was.
After curing, a test piece having a width of 400 mm and a length of 500 mm was cut out from the obtained adhesive sheet roll at a position 10 m long from the end of the adhesive sheet on the winding start side (inside, winding core side). Was evaluated.
(1) Evaluation before curing (initial curability):
The thickness of the test piece was measured using a dial gauge. The evaluation criteria are as follows.
<Evaluation criteria>
⊚: The adhesive layer is sufficiently cured, and the thickness of the adhesive sheet can be measured accurately (good).
◯: The adhesive layer is a little soft, but the thickness of the adhesive sheet can be measured (no problem in practical use).
X: The adhesive layer has fluidity, and the thickness of the adhesive sheet cannot be measured (there is a problem in practical use).
(2) Evaluation after curing (surface appearance):
The test piece was held over a fluorescent lamp to visually evaluate the surface appearance of the test piece. The evaluation criteria are as follows.
<Evaluation criteria>
◎: Yuzu skin and winding core step marks are not seen (good),
◯: Yuzu skin and / or some traces of step on the core are seen (no problem in practical use),
X: Yuzu skin and / or winding core step marks are seen (there is a problem in practical use).

(Adhesion to glass)
A test piece having a width of 100 mm and a length of 150 mm was cut out from the adhesive sheet. Next, the release sheet was peeled off from the test piece under a 23 ° C.-50% RH atmosphere, and the surface of the exposed adhesive layer was attached to a glass plate. When the adhesive sheet was attached to the glass plate, wrinkles were formed on the adhesive sheet, air bubbles were caught in the attachment interface, or different parts of the adhesive layers were in close contact with each other, which was judged as "defective". This evaluation was performed 10 times. The evaluation criteria are as follows.
<Evaluation criteria>
⊚: The number of defects is 0 (good),
◯: The number of defects is 1-2 times (no problem in practical use),
X: The number of defects is 3 or more (there is a problem in practical use).

(Adhesive strength to glass)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the adhesive sheet. Next, the release sheet was peeled from the test piece under a 23 ° C.-50% RH atmosphere, the surface of the exposed adhesive layer was attached to a glass plate, and a 2 kg roller was reciprocated once on the adhesive sheet to crimp them. And left for 24 hours. Then, using a tensile tester, a 90 ° peeling test of the adhesive sheet was carried out at a peeling speed of 0.3 m / min, and the adhesive strength was measured. In general, it can be said that the one having low adhesive strength to glass and easy to peel off is more practical for surface protection.

(Probe tack)
A test piece having a width of 30 mm and a length of 30 mm was cut out from the adhesive sheet. Then, the release sheet was peeled off from the test piece under a 23 ° C.-50% RH atmosphere, and the probe tack on the surface of the exposed adhesive layer was measured according to JIS Z0237. A probe tack measuring device (manufactured by Tester Sangyo Co., Ltd.) was used as the device. A stainless steel probe (20 g) having a diameter of 5 mmφ was brought into contact with the surface of the adhesive layer at a contact load of 1.0 N / cm ² for 1 second, and then the probe was separated from the surface of the adhesive layer at a speed of 10 mm / sec. The peeling force of the probe at this time was measured. The measurement was carried out three times, and the average value was calculated.

(Shear force)
A test piece having a width of 10 mm and a length of 50 mm is cut out from the adhesive sheet, a marked line is drawn at a position 20 mm from one end in the length direction, and the area from one end to the marked line (the area of 10 mm wide and 20 mm long) is the test area. And said. In a 23 ° C.-50% RH atmosphere, the release sheet was peeled off from the test piece, the above test area on the surface of the exposed adhesive layer was attached to a glass plate, and a 2 kg roller was reciprocated once on the adhesive sheet. Was crimped. Then, using a tensile tester, the test piece and the glass plate were pulled in opposite directions by 180 ° under the condition of a peeling speed of 50 mm / min, and the shear force was measured. The measurement was carried out 5 times, and the average value was calculated.

(Water contact angle on the surface of the adhesive layer)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the adhesive sheet. Next, the release sheet was peeled off from the test piece under a 23 ° C.-50% RH atmosphere, and the water contact angle on the surface of the exposed adhesive layer was measured. Using DM-501 manufactured by Kyowa Interface Science Co., Ltd. as an apparatus, the water contact angle was measured 61000 ms after dropping water on the surface of the adhesive layer. The value calculated by the θ / 2 method was used as the measured value. The measurement was carried out 5 times, and the average value was calculated.

(Water contact angle of the surface on the non-forming side of the adhesive layer of the base sheet)
A test piece having a width of 25 mm and a length of 100 mm was cut out from the adhesive sheet. Next, the water contact angle of the surface on the non-forming side of the adhesive layer of the base sheet was measured under a 23 ° C.-50% RH atmosphere. Using DM-501 manufactured by Kyowa Interface Science Co., Ltd. as an apparatus, the water contact angle was measured 1000 ms after the water was dropped. The value calculated by the θ / 2 method was used as the measured value. The measurement was carried out 5 times, and the average value was calculated.

(Moisture heat bleaching resistance)
Two test pieces having a width of 25 mm and a length of 100 mm were cut out from the adhesive sheet.
One of the test pieces was used as it was for the evaluation of haze (no heat transition). The other test piece was left to stand in a 60 ° C.-95% RH atmosphere for 48 hours, returned to a room temperature atmosphere (20 to 25 ° C.), cooled sufficiently, and then subjected to a haze evaluation (with a course of moist heat). For each of the test pieces, the haze was measured according to JIS K7165 in a state where the release sheet was peeled off from the test pieces in an atmosphere of 23 ° C.-50% RH and the adhesive layer was exposed. As an apparatus, a Turbodimeter NDH5000W (manufactured by Nippon Denshoku Kogyo Co., Ltd.) was used. A D65 light source was used as the light source. ΔH was calculated based on the following formula. The evaluation criteria are as follows.
ΔH = Hb-Ha
(In the formula, Ha is the haze of the test piece without the heat and humidity process, and Hb is the haze of the test piece with the heat and humidity process.)
<Evaluation criteria>
⊚: ΔH is less than 2.0 (excellent),
◯: ΔH is 2.0 or more and less than 3.0 (good),
Δ: ΔH is 3.0 or more and less than 4.0 (no problem in practical use),
X: ΔH is 4.0 or more (there is a problem in practical use).

[Evaluation results]
The evaluation results are shown in Table 3.
In Examples 1 to 12, a polyurethane polyol (A), which is a copolymerization reaction product of one or more polyols (x) and one or more polyisocyanates (y), a polyfunctional isocyanate compound (B), and the like. A urethane-based pressure-sensitive adhesive containing 0.08 to 0.70 parts by mass of a metal-containing catalyst (MC) with respect to 100 parts by mass of the polyurethane polyol (A) is produced, and a pressure-sensitive adhesive containing a pressure-sensitive adhesive layer having a thickness of 50 μm is used. Manufactured the sheet.

All of the urethane-based adhesives obtained in Examples 1 to 12 had good or relatively good pot life evaluation results. In each of Examples 1 to 12, even if the thick film coating was performed, the coating layer had excellent or good initial curability, and an adhesive layer having a good surface appearance could be formed after curing.

All of the adhesive sheets obtained in Examples 1 to 12 have excellent or good evaluation results of adhesiveness to glass, adhesive force to glass, probe tack, and shearing force, and are generally required as an adhesive sheet. The performance was excellent or good. In particular, the pressure-sensitive adhesive sheets obtained in Examples 2 to 10 using the plasticizer (P) were excellent in these performances.

All of the pressure-sensitive adhesive sheets obtained in Examples 1 to 12 had excellent, good, or relatively good moisture-heat bleaching resistance. In particular, Example 1 using a base sheet containing an antistatic layer containing a conductive polymer (EP) without using a plasticizer (P), and a plasticizer (P) containing one or more EO groups. The pressure-sensitive adhesive sheets obtained in Examples 2 to 9 using the base sheet containing the antistatic layer containing the conductive polymer (EP) used had excellent moisture-heat whitening resistance.

In Comparative Example 1, since the amount of the metal-containing catalyst (MC) was insufficient, the initial curability of the obtained urethane-based pressure-sensitive adhesive was poor, and the thick film coating property was poor. The obtained adhesive sheet also had poor evaluation results of adhesiveness to glass, adhesive force to glass, probe tack, and shearing force. Moisture heat bleaching resistance was also poor.

In Comparative Example 2, a plasticizer (P) containing one or more EO groups was used, and a base sheet containing an antistatic layer containing a conductive polymer (EP) was used, but only an amine catalyst was used as a catalyst. The obtained adhesive sheet had poor moisture and heat whitening resistance.
In Comparative Example 3, since the polyurethane polyol (A) was not used, the initial curability of the coating layer was insufficient, and the thick film coating property was poor. The obtained adhesive sheet had poor evaluation results of adhesiveness to glass, adhesive force to glass, probe tack, and shearing force. Moisture heat bleaching resistance was also poor.

In Comparative Example 4, since the amount of the metal-containing catalyst (MC) was excessive, the evaluation result of the pot life was poor, and the coating itself could not be performed.
In Comparative Example 5, since the polyfunctional isocyanate compound (B) was not used, the coating layer made of the obtained urethane-based pressure-sensitive adhesive was not cured in the heating step, and the pressure-sensitive adhesive layer could not be formed.

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

10X, 10Y, 10Z Adhesive sheet 11 Base sheet 11A Sheet body 11B Antistatic layer 12 Adhesive layer 13X, 13Y, 13Z Release sheet 13A Sheet body 13B Antistatic layer 13L Release agent layer

Claims (9)

A pressure-sensitive adhesive sheet having removability, which comprises a base material sheet and a pressure-sensitive adhesive layer made of a cured product of a urethane-based pressure-sensitive adhesive formed on one surface of the base material sheet.
The urethane adhesive is
Polyurethane polyol (A), which is a copolymerization product of one or more polyols (x) and one or more polyisocyanates (y),
Polyfunctional isocyanate compound (B) and
A polyurethane polyol (A) .08-.70 parts by weight of the metal-containing catalyst relative to 100 parts by mass (MC),
Contains one or more plasticizers (P)
One or more plasticizers (P) contain an organic acid ester having one or more ethyleneoxy groups in one molecule.
The adhesive layer is an adhesive sheet having a water contact angle of 40 to 80 ° after 61000 ms has passed since water was dropped on the surface of the adhesive layer . The pressure-sensitive adhesive sheet according to claim 1, wherein the probe tack of the pressure-sensitive adhesive layer is 0.01 to 0.30 N / cm ² . The adhesive layer when the adhesive layer side of the adhesive sheet is attached to a glass plate with a contact area of 10 × 20 mm ^{2 and} the adhesive sheet is peeled from the glass plate in the 180 ° direction at a peeling speed of 50 mm / min. The adhesive sheet according to claim 1 or 2, wherein the shearing force of the adhesive sheet is 5 to 25 N / cm ² . The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the amount of one or more polyester polyols in the total amount of one or more polyols (x) is 50 to 100% by mass. The pressure-sensitive adhesive sheet according to claim 4 , wherein the amount of one or more bifunctional polyester polyols in the total amount of one or more polyester polyols is 20 to 100% by mass. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , wherein the base material sheet includes a sheet body and an antistatic layer formed on a non-forming side surface of the pressure-sensitive adhesive layer of the sheet body. The pressure-sensitive adhesive sheet according to claim 6 , wherein the antistatic layer contains a conductive polymer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer has a thickness of 30 to 200 μm. The adhesive sheet according to any one of claims 1 to 8, which is for surface protection.

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