KR102410982B1 - Pressure sensitive adhesive sheet - Google Patents

Abstract

Provided is a pressure-sensitive adhesive sheet that can cure a coating layer composed of a urethane pressure-sensitive adhesive in a manufacturing process relatively quickly and form a pressure-sensitive adhesive layer with a good surface appearance, and can thicken the pressure-sensitive adhesive layer if necessary.
The present invention relates to a pressure-sensitive adhesive sheet (10) including a base sheet (11) and an adhesive layer (12) composed of a cured product of a urethane pressure-sensitive adhesive formed on one side of the base sheet (11). The urethane pressure-sensitive adhesive is a polyurethane polyol (A) which is a copolymerization reaction product of at least one polyol (x) and at least one polyisocyanate (y), a polyfunctional isocyanate compound (B), and a polyurethane polyol (A) 100 mass 0.08-0.70 mass parts of metal containing catalysts (MC) are included with respect to a part.

Description

Adhesive sheet {PRESSURE SENSITIVE ADHESIVE SHEET}

This application claims priority on the basis of Japanese Patent Application No. 2016-193382 for which it applied on September 30, 2016, and all the disclosures are brought here.

The present invention relates to an adhesive sheet.

DESCRIPTION OF RELATED ART Conventionally, the adhesive sheet in which the adhesive layer was formed on the base material sheet is widely used as a surface protection sheet of various members. As the pressure-sensitive adhesive, there are mainly an acrylic pressure-sensitive adhesive and a urethane-based pressure-sensitive adhesive. In general, acrylic pressure-sensitive adhesives are excellent in adhesive strength, but when the pressure-sensitive adhesive sheet is attached to an adherend, it tends to easily attract air bubbles to the bonding interface. Acrylic pressure-sensitive adhesives have poor re-peelability after being pasted on an adherend, and thus tend to easily cause contamination of the adherend where the adhesive remains on the surface of the adherend after re-peelling. On the other hand, the urethane-based pressure-sensitive adhesive tends to be excellent in re-peelability while having moderate adhesiveness to the adherend and good adhesion to the adherend.

In the present specification, "adhesive" is an adhesive (re-peelable adhesive) having re-peelability, and "adhesive sheet" is an adhesive sheet (re-peelable adhesive sheet) having re-peelability.

A flat panel display such as a liquid crystal display (LCD), and a touch panel display combining a related flat panel display and a touch panel are widely used in electronic devices such as televisions (TVs), personal computers (PCs), mobile phones, and portable information terminals. have. The urethane pressure-sensitive adhesive sheet is suitably used as a surface protection sheet for flat panel displays and touch panel displays, and for substrates and optical members manufactured or used in their manufacturing processes.

A general method for producing a pressure-sensitive adhesive sheet includes a coating step of coating an adhesive on a base sheet, a heating step of heat-drying the formed coating layer to form an adhesive layer containing a cured product of the pressure-sensitive adhesive, and winding the obtained pressure-sensitive adhesive sheet on a core A winding process made into the form of an adhesive sheet roll, and a curing process of curing the adhesive sheet roll are included.

In manufacture of an adhesive sheet, it is preferable that a coating layer hardens comparatively quickly.

When the coating layer is cured relatively quickly, the coating layer and the adhesive layer are hardly affected by the hot air during heat drying of the coating layer, and mechanical stress during winding and curing of the pressure-sensitive adhesive sheet obtained after heat drying. Therefore, defects such as wick step marks, orange peel, and winding habit can be suppressed, and a pressure-sensitive adhesive sheet having an adhesive layer having a good surface appearance can be manufactured.

When the coating layer is cured relatively quickly, it is easy to apply a thick film of the pressure-sensitive adhesive. Since the adhesive layer can be thickened, it is possible to form an adhesive layer excellent in cushioning properties and in the performance (impact resistance, etc.) for protecting adherends such as various optical members from impacts and the like.

When the coating layer is cured relatively quickly, the curing period can be shortened.

However, in general, the urethane-based pressure-sensitive adhesive tends to be difficult to cure because the molecular weight of the main component resin is smaller than that of the acrylic pressure-sensitive adhesive.

Patent Document 1 discloses at least one polyol (A) including a polyol (A1) having three OH groups and having a number average molecular weight Mn of 8000 to 20000 and a urethane-based pressure-sensitive adhesive comprising at least one polyfunctional isocyanate compound (B) A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer composed of a cured product is disclosed (Claim 1, 9).

The pressure-sensitive adhesive sheet described in Patent Document 1 is obtained by curing a urethane pressure-sensitive adhesive containing a polyol and a polyfunctional isocyanate compound without using a polyurethane polyol by a so-called one-shot method to form an adhesive layer.

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

Patent Document 3 discloses a urethane pressure-sensitive adhesive containing a prepolymer of polyurethane and a carboxylic acid ester, wherein the carboxylic acid ester satisfies at least one of the following conditions 1 and 2 (claim 1).

(Condition 1) The said carboxylic acid ester contains an ether bond in a molecule|numerator.

(Condition 2) The said carboxylic acid ester contains 31 or more carbon atoms in 1 molecule.

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

In addition, the code|symbol of the various component in patent documents 1-4 describes the code|symbol described in the publication as it is, and it is independent of the code|symbol of the various component used with the adhesive sheet of this invention.

Japanese Patent Laid-Open No. 2014-111701 Japanese Patent Laid-Open No. 2015-7226 Japanese Patent Laid-Open No. 2015-151429 Japanese Patent Laid-Open No. 2014-028878

Patent Document 1 describes that the urethane-based pressure-sensitive adhesive preferably contains a leveling agent to suppress uneven appearance due to orange peel (paragraph 0073).

The urethane-type adhesive of patent document 1 is suppressing the orange peel by adding a leveling agent without improving sclerosis|hardenability. Therefore, it is impossible to realize the reduction of the thick film process and the curing period.

Patent Document 2 describes that the component (A) has a first-class hydroxyl group at the terminal, so that the reaction with the polyfunctional isocyanate compound (B) in the pressure-sensitive adhesive proceeds rapidly, and no time is required for dry curing. (paragraph 0036). However, in the urethane-based pressure-sensitive adhesive containing any polyurethane polyol, it is preferable that relatively fast curing is realized.

Patent Document 3 describes that the pressure-sensitive adhesive can increase the heating temperature after application to the substrate, and that the curing reaction proceeds easily by increasing the heating temperature as much as possible (paragraph 0140). However, in Patent Document 3, "The heating temperature is preferably a temperature exceeding 90°C, more preferably 100°C or more, and still more preferably 130°C or more. The upper limit of the heating temperature is, for example, 150° C. or less” (paragraph 0139). Such a heating temperature is a heating temperature generally employed in the prior art, and the curing reaction rate cannot be increased more than in the prior art.

The one-shot method employed 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 in the manufacturing process, the coating layer composed of the urethane-based adhesive can be cured relatively quickly, and an adhesive layer having a good surface appearance can be formed, and the adhesive layer can be thickened as necessary. An object of the present invention is to provide a possible adhesive sheet.

The pressure-sensitive adhesive sheet of the present invention,

It is a pressure-sensitive adhesive sheet comprising a base sheet and an adhesive layer composed of a cured product of a urethane-based pressure-sensitive adhesive formed on one side of the base sheet,

The urethane-based pressure-sensitive adhesive,

A polyurethane polyol (A) which is a copolymerization reaction product of at least one polyol (x) and at least one polyisocyanate (y);

A polyfunctional isocyanate compound (B), and

0.08-0.70 mass parts of metal containing catalysts (MC) are included with respect to 100 mass parts of polyurethane polyols (A).

In general, a sheet-like article is called a "tape", a "film", or a "sheet" depending on the thickness and width. This specification does not distinguish them in particular, and assumes that the term "sheet" is used as a term indicating a concept encompassing them.

In this specification, "ethyleneoxy group" is a group represented by general formula "-CH ₂ CH ₂ O-", and may abbreviate|omit and describe as "EO group". Similarly, ethylene oxide which forms an EO group by a ring-opening reaction may be abbreviate|omitted and described with "EO".

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

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet capable of curing the coating layer composed of the urethane pressure-sensitive adhesive relatively quickly in the manufacturing process, forming an adhesive layer having a good surface appearance, and thickening the pressure-sensitive adhesive layer if necessary.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the adhesive sheet of 1st Embodiment which concerns on this invention,
Fig. 2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention;
3 : is a schematic sectional drawing of the adhesive sheet of 3rd Embodiment which concerns on this invention.

The present invention relates to a pressure-sensitive adhesive sheet including a base sheet and an adhesive layer composed of a cured product of a urethane-based pressure-sensitive adhesive.

[Urethane adhesive]

The urethane pressure-sensitive adhesive used in the present invention contains at least one polyurethane polyol (A), at least one polyfunctional isocyanate compound (B), and at least one metal-containing catalyst (MC).

(Polyurethane Polyol (A))

The polyurethane polyol (A) is a reaction product obtained by copolymerizing at least one polyol (x) and at least one polyisocyanate (y). The copolymerization reaction may be carried out in the presence of one or more catalysts, if necessary. One or more types of solvents can be used for a copolymerization reaction as needed.

<Polyol (x)>

The type of polyol (x) is not particularly limited, and examples thereof include polyester polyol, polyether polyol, polyacrylic polyol, polycaprolactone polyol, polycarbonate polyol, and castor oil-based polyol. Among them, polyester polyols, polyether polyols, and combinations thereof are preferred.

A well-known thing can be used as polyester polyol, The compound (esterified product) obtained by the esterification reaction of 1 or more types of polyol components and 1 or more types of acid components is mentioned.

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-nondiol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, and hexane triol, and the like.

As the acid component of the raw material, succinic acid, methylsuccinic acid, adipic acid, pimeric acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanoic acid, dimer acid, 2-methyl-1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, and acid anhydrides thereof etc. can be cited.

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 still more preferably 800 to 3,000. Since Mn is 500 or more, gelation of a polyurethane polyol (A) is suppressed effectively. Since Mn is 5,000 or less, the cohesive force of the polyurethane polyol (A) becomes very suitable.

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

As an initiator, a hydroxyl-containing compound, an amine, etc. are mentioned. Specifically, bifunctional initiators such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylenediamine ; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamine; A pentafunctional initiator, such as diethylenetriamine, etc. can be mentioned.

Examples of the oxirane compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); Tetrahydrofuran (THF) is one of them.

As the polyether polyol, an alkylene oxide adduct (also referred to as "polyoxyalkylene polyol") which is an active hydrogen-containing compound is preferable. Among them, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol; Trifunctional polyether polyols, such as an alkylene oxide adduct of glycerol, etc. 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, particularly preferably 800 to 3,000. Since 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 high cohesive force, and the occurrence of surface appearance defects such as wicking step traces, orange peel, and winding habit of the adhesive layer in the manufacturing process of the adhesive sheet is suppressed, the raw material of polyurethane polyol (A) The phosphorus at least one polyol (x) preferably contains at least one polyester polyol. From the viewpoint of effectively suppressing surface appearance defects, the greater the amount of the at least one polyester polyol relative to the total amount of the at least one polyol (x), the better, preferably 50 to 100 mass %, more preferably 60 to 100 mass %, especially More preferably, it is 70-100 mass %.

The number of functional groups (the number of hydroxyl groups) of one or more types of polyols (x) is arbitrary, and several types of polyols from which the number of functional groups differ can be used together as needed. In general, the bifunctional polyol has two-dimensional crosslinking and can impart appropriate flexibility to the pressure-sensitive adhesive layer. The trifunctional or higher polyol has three-dimensional crosslinking and can impart moderate hardness to the pressure-sensitive adhesive layer. The number of functional groups of the at least one polyol (x) may be selected according to the use or required properties.

Generally, compared with an acrylic adhesive, since the molecular weight of main component resin is small, a urethane-type adhesive tends to be hard to harden|cure.

In general, as the number of functional groups in the polyol (x) decreases, the crosslinkability of the obtained polyurethane polyol (A) decreases and the curability tends to decrease. Specifically, when the at least one polyol (x) contains at least one bifunctional polyol, particularly when the at least one polyol (x) consists only of at least one bifunctional polyol, the polyurethane polyol (A) obtained There is a tendency that the curability of the

When the at least one polyol (x) contains at least one bifunctional polyol, the resulting urethane-based pressure-sensitive adhesive is difficult to cure and has the advantage of realizing good pot life (pot life), but especially under thick film coating conditions There is a fear that the initial curability of the coating layer composed of the urethane pressure-sensitive adhesive may become insufficient.

Although it will be described in detail later, since the urethane-based pressure-sensitive adhesive used in the present invention contains a specific amount of one or more metal-containing catalysts (MC), good pot life regardless of the type of polyol (x), which is a raw material of the polyurethane polyol (A) It is possible to effectively increase the curability of the coating layer composed of the urethane-based pressure-sensitive adhesive while realizing it.

The present invention is effective when using a polyurethane polyol (A) having low curability, for example, when using a polyurethane polyol (A) obtained using one or more difunctional polyester polyols.

The urethane-based adhesive has a good pot life, the adhesive layer can have high cohesion, and the occurrence of surface appearance defects such as wick step marks, orange peel, and winding habit of the adhesive layer in the manufacturing process of the adhesive sheet is suppressed. , it is possible to effectively increase the curability of the coating layer even under thick film coating conditions, so that the at least one polyol (x), which is a raw material of the polyurethane polyol (A), preferably contains at least one bifunctional polyester polyol, and at least one The amount of the at least one bifunctional polyester polyol relative to the total amount of the polyester polyol is preferably 20 to 100% by mass, more preferably 30 to 100% by mass, and still more preferably 50 to 100% by mass.

<Polyisocyanate (y)>

A well-known thing can be used as a polyisocyanate compound (y), An aromatic polyisocyanate, an aliphatic polyisocyanate, an aromatic aliphatic polyisocyanate, an alicyclic polyisocyanate, etc. are mentioned.

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

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

As aromatic aliphatic polyisocyanate, ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethyl Benzene, 1,4-tetramethylxylene diisocyanate, 1,3-tetramethylxylene diisocyanate, etc. are mentioned.

Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethyl cyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl -2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatemethyl)cyclohexane are mentioned.

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

As polyisocyanate (y), 4,4'- diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5- trimethylcyclohexyl isocyanate (isophorone diisocyanate), etc. are preferable.

In the polymerization of the polyurethane polyol (A), the at least one polyol (x) and the at least one polyisocyanate (y) are at least one polyisocyanate with respect to the number of moles of hydroxyl groups (OH) in the at least one polyol (x). It is preferable to make it react in the ratio used as 0.5-0.95 of ratio (NCO/OH functional group ratio) of the number of moles of isocyanate group (NCO) in (y).

<Catalyst>

For polymerization of the polyurethane polyol (A), one or more catalysts can be used as needed. As a catalyst, a well-known thing can be used, A metal containing catalyst (MC) and another catalyst (non-metal containing catalyst) (NMC) are mentioned.

When the catalyst used for the polymerization of the polyurethane polyol (A) comprises at least one metal-containing catalyst (MC), the at least one metal-containing catalyst (MC) used for the polymerization of the polyurethane polyol (A) is finally It may remain as a component of a urethane-type adhesive. Examples of the metal-containing catalyst (MC) include tin-based compounds and non-tin-based compounds. Examples of these will be described later.

As another catalyst (non-metal-containing catalyst) (NMC), a tertiary amine compound or the like is mentioned. Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).

The catalyst can be used 1 type or 2 or more types.

When several types of polyols (x) having different reactivity are used in combination, there is a fear that gelation or cloudiness of the reaction solution may easily occur in a single catalyst system depending on the difference in reactivity. In this case, by using two or more types of catalysts, the reaction (eg, reaction rate, etc.) can be easily controlled and the above problems can be solved. In a series in which several 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 catalysts is not particularly limited, and examples thereof include tertiary amine/organometallic, tin/non-tin, and tin/tin. Preferred are tin-based/tin-based, more preferably dibutyltin dilaurate and tin 2-ethylhexanoate.

The mass ratio of tin 2-ethylhexanoate to dibudyltin dilaurate (tin 2-ethylhexanoate/dibutyltin dilaurate) is not particularly limited, preferably more than 0 and less than 1, more preferably 0.2 to is 0.6. When the mass ratio is less than 1, the balance of catalytic activity is good, and gelation can be effectively suppressed.

The amount of the at least one catalyst used is not particularly limited, and is preferably 0.01 to 1.0 mass % with respect to the total amount of the at least one polyol (x) and the at least one organic polyisocyanate (y).

<solvent>

One or more types of solvents can be used for polymerization of a polyurethane polyol (A) as needed. As the solvent, a known solvent can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone.

<Polymerization method>

The polymerization method in particular of a polyurethane polyol (A) is not restrict|limited, Well-known polymerization methods, such as a block polymerization method and a solution polymerization method, are applicable.

The polymerization procedure is not particularly limited,

Step 1) at least one polyol (x), at least one polyisocyanate (y), optionally at least one catalyst, and optionally at least one solvent in a batch in a flask;

Step 2) At least one polyol (x), optionally at least one catalyst, and optionally at least one solvent are put into a flask, and one or more polyisocyanates (y) are added dropwise thereto order can be selected.

Step 2) is preferable because the reaction can be easily controlled.

The reaction temperature in the case of using a catalyst becomes like this. Preferably it is less than 100 degreeC, More preferably, it is 85-95 degreeC. When the reaction temperature is less than 100°C, it is possible to easily control the reaction rate and cross-linking structure and the like, and thus it is easy to produce the polyurethane polyol (A) having a desired molecular weight.

The reaction temperature in the case of not using a catalyst is preferably 100°C or higher, more preferably 110°C or higher. The reaction time in the case of not using a catalyst becomes like this. Preferably it is 3 hours or more.

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

The hydroxyl value in particular of a polyurethane polyol (A) is not restrict|limited, Preferably it is 5-40 mgKOH/g, More preferably, it is 5-35 mgKOH/g. When the hydroxyl value of the polyurethane polyol (A) is 5 mgKOH/g or more, properties such as adhesive strength, heat resistance, and heat-and-moisture resistance of the adhesive layer become good. When the hydroxyl value of a polyurethane polyol (A) is 35 mgKOH/g or less, the softness|flexibility of an adhesive layer becomes favorable.

In addition, the hydroxyl value can be measured by the method described in the item 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), a known compound can be used, and the compound exemplified by the polyisocyanate (y), which is a raw material of the polyurethane polyol (A) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, alicyclic polyisocyanate, and their trimethylolpropane adduct/biuret/trimer) can be used.

The ratio of the number of moles of isocyanate groups (NCO) of the at least one polyfunctional isocyanate compound (B) to the number of moles of hydroxyl groups (OH) of the at least one polyurethane polyol (A) (NCO/OH functional group ratio) is not particularly limited and preferably 1.0 to 4.0, more preferably 1.25 to 3.75, 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 improved, and when the NCO/OH functional group ratio is 4.0 or less, the adhesive force of the adhesive layer is improved.

The blending amount of the at least one polyfunctional isocyanate compound (B) with respect to 100 parts by mass of the at least one polyurethane polyol (A) is not particularly limited, preferably 1 to 30 parts by mass, more preferably 5 to 25 parts by mass to be. The cohesive force of an adhesion layer becomes favorable that a compounding quantity is 1 mass part or more, and the adhesive force of an adhesion layer becomes favorable that a compounding quantity is 30 mass parts or less.

(Plasticizer (P))

The urethane-based pressure-sensitive adhesive used in the present invention may further include one or more plasticizers (P) as needed. When the urethane-based pressure-sensitive adhesive contains one or more plasticizers (P), the wettability of the pressure-sensitive adhesive layer is improved, and when the pressure-sensitive adhesive sheet is pasted to an adherend, it becomes difficult to attract air bubbles to the bonding interface. Although it does not restrict|limit especially as a plasticizer (P), From a viewpoint, such as compatibility with another component, C10-30 organic acid ester is preferable.

Examples of the organic acid ester having 10 to 30 carbon atoms include esters of monobasic or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and tetravalent alcohols and esters, and esters of monobasic or polybasic acids having 6 to 18 carbon atoms with polyalkylene glycol.

Examples of esters of monobasic or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms include isostearyl laurate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitate, and triisocetyl trimellitate are mentioned.

Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include myristic oleic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid. Ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitan, etc. can be mentioned as a tetrahydric or less alcohol.

Examples of esters of monobasic or polybasic acids having 6 to 18 carbon atoms and polyalkylene glycol include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexyl acid, polyethylene glycol dilaurate, polyethylene glycol dioleate, and adipic acid. Dipolyethylene glycol methyl ether and the like are mentioned.

The at least one plasticizer (P) preferably contains at least one organic acid ester (also referred to as an EO group-containing organic acid ester) having at least one ethyleneoxy group (EO group) in one molecule.

In general, when the adhesive layer is exposed to a high-temperature, high-humidity environment, it may become cloudy (also referred to as whitening) under the influence of moisture in the external environment, thereby deteriorating its appearance. Then, it is preferable that an adhesion layer has favorable heat-and-moisture whitening resistance. By using 1 or more types of EO group containing organic acid ester, the hydrophilicity of an adhesive layer can improve and moist-heat whitening can be suppressed. Due to the improvement of the hydrophilicity of the adhesive layer, the transfer of moisture between the adhesive layer and the external environment is easy to occur, so even if moisture enters the adhesive layer from the outside, the moisture is easily discharged from the adhesive layer to the external environment, so that the amount of moisture in the adhesive layer is relatively can be kept low.

As an indicator of hydrophilicity, a water contact angle can be cited. By using at least one EO group-containing organic acid ester, for example, an adhesive layer having a water contact angle of 40 to 80° after 61000 ms has elapsed after water is dropped on the surface of the adhesive layer can be formed.

In addition, "water contact angle" can be measured by the method described in the item of [Example].

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

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

The compounding quantity of 1 or more types of plasticizer (P) with respect to 100 mass parts of 1 or more types of polyurethane polyols (A) becomes like this. Preferably it is 10-70 mass parts, More preferably, it is 20-50 mass parts. The addition effect (wettability improvement effect) of a plasticizer (P) as a compounding quantity is 10 mass parts or more can express effectively. When the compounding amount is 70 parts by mass or less, the amount of the polyurethane polyol (A), which is the main active ingredient of the originally required pressure-sensitive adhesive, is sufficiently secured to ensure the performance required as the pressure-sensitive adhesive.

(Metal containing catalyst (MC))

The urethane-based pressure-sensitive adhesive used in the present invention includes at least one metal-containing catalyst (MC).

In addition, the timing of addition of the at least one metal-containing catalyst (MC) is not particularly limited. The at least one metal-containing catalyst (MC) may be added during polymerization of the at least one polyurethane polyol (A). At least one metal-containing catalyst (MC) may be added when preparing a urethane pressure-sensitive adhesive by blending at least one polyurethane polyol (A), at least one polyfunctional isocyanate compound (B), and, if necessary, other optional components. .

Examples of the metal-containing catalyst (MC) include tin-based compounds and non-tin-based compounds.

Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, Tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and 2-ethyl and tin hexanoate.

Examples of the non-tin-based compound include titanium-based compounds such as dibutyl titanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead systems such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron systems such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt type, such as cobalt benzoate and cobalt 2-ethylhexanoate; Zinc types, such as zinc naphthenate and zinc 2-ethylhexanoate; Zirconium systems, such as zirconium naphthenate, are mentioned.

The addition amount of the at least one metal-containing catalyst (MC) to 100 parts by mass of the at least one polyurethane polyol (A) is 0.08 to 0.70 parts by mass, preferably 0.09 to 0.65 parts by mass, particularly preferably 0.10 to 0.60 parts by mass to be.

In general, the urethane pressure-sensitive adhesive tends to be difficult to cure because the molecular weight of the main component resin is smaller than that of the acrylic pressure-sensitive adhesive.

In general, as the number of functional groups in the polyol (x) is small, the crosslinkability of the polyurethane polyol (A) obtained decreases and the curability tends to decrease. Specifically, when the at least one polyol (x) contains at least one bifunctional polyol, particularly when the at least one polyol (x) consists only of at least one bifunctional polyol, the obtained polyurethane polyol (A) has curability tends to decrease.

When the at least one polyol (x) contains at least one bifunctional polyol, the obtained urethane pressure-sensitive adhesive is difficult to cure and has the advantage of realizing a good pot life, but especially in the thick film coating condition of the coating layer composed of the urethane pressure-sensitive adhesive There exists a possibility that initial stage sclerosis|hardenability may become inadequate.

When the addition amount of the at least one metal-containing catalyst (MC) is 0.08 parts by mass or more, the curability of the coating layer composed of the urethane pressure-sensitive adhesive can be effectively improved regardless of the type of the polyurethane polyol (A). When the addition amount of the at least one metal-containing catalyst (MC) is 0.70 parts by mass or less, the urethane-based pressure-sensitive adhesive may have a good pot life.

In the manufacturing process of the adhesive sheet, when the coating layer cures relatively quickly, the coating layer and the adhesive layer are affected by hot air during heat drying of the coating layer or mechanical stress received during winding of the adhesive sheet obtained after heat drying. difficult. Therefore, the occurrence of defects such as wick step marks, orange peel, and winding habit is suppressed, and a pressure-sensitive adhesive sheet having an adhesive layer having a good surface appearance can be manufactured.

When the coating layer cures relatively quickly, it is easy to apply a thick film of the pressure-sensitive adhesive. Since the adhesive layer can be thickened, it is possible to form an adhesive layer excellent in cushioning properties and excellent in performance (impact resistance, etc.) for protecting adherends such as various optical members from impacts and the like.

When the coating layer cures relatively quickly, the curing period can be shortened.

In addition, the urethane-based pressure-sensitive adhesive used in the present invention may contain one or more other catalysts (non-metal-containing catalysts) (NMC) according to one or more metal-containing catalysts (MC) as needed. As another catalyst (a non-metal-containing catalyst) (NMC), a tertiary amine-based compound or the like can be cited. 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 solvents as needed. As a solvent, a well-known thing can be used, Methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned.

(discoloration inhibitor)

The urethane-based pressure-sensitive adhesive used in the present invention may include one or more types of deterioration inhibitors as necessary. Accordingly, it is possible to suppress deterioration of various properties due to long-term use of the adhesive layer. As the deterioration inhibitor, a hydrolysis-resistant agent, antioxidant, ultraviolet absorber, light stabilizer, and the like can be cited.

(Hydrolysis resistant agent)

When a hydrolysis reaction occurs in the pressure-sensitive adhesive layer and a carboxyl group is generated under a high-temperature, high-humidity environment or the like, one or more types of hydrolysis-resistant agents can be used to block the carboxyl group.

Examples of the hydrolysis-resistant agent include carbodiimide-based, isocyanate-based, oxazoline-based, and epoxy-based agents. Among them, 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 dicyclohexyl carbodiimide, diisopropyl carbodiimide, dimethyl carbodiimide, diisobutyl carbodiimide, dioctylcarbodiimide, diphenyl carbodiimide, and naphthyl carbodiimide. Mead, etc. can be cited.

The polycarbodiimide compound can be produced by subjecting diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimidization catalyst. Here, as the diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, and 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, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, etc. are mentioned. Examples of the carbodiimidization catalyst include 1-phenyl-2-phosphorine-1-oxide, 3-methyl-2-phosphorine-1-oxide, and 1-ethyl-3-methyl-2-phosphorine-1-oxide. Phosphorine oxides, such as oxide, 1-ethyl-2-phosphorine-1-oxide, and these 3-phosphorine isomers, etc. are mentioned.

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

Examples of the oxazoline-based hydrolysis inhibitor include 2,2'-o-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-p-phenyl Lenbis (2-oxazoline), 2,2'-p-phenylenebis (4-methyl-2-oxazoline), 2,2'-m-phenylenebis (4-methyl-2-oxazoline) , 2,2'-p-phenylenebis (4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis (4,4'-dimethyl-2-oxazoline), 2 ,2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylene bis(2-oxazoline), 2,2'-ethylenebis(4-methyl-2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline).

Examples of the epoxy-based hydrolyzing agent include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol; polyglycidyl ethers of aliphatic polyols such as sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, and trimethylolpropane; polyglycidyl ethers of alicyclic polyols such as cyclohexanedimethanol; diglycidyl esters or polyglycidyl esters of aliphatic or aromatic polyvalent carboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimeric acid, adipic acid, and sebacic acid; resorcinol, bis-(p-hydroxyphenyl)methane, 2,2-bis-(p-hydroxyphenyl)propane, tris-(p-hydroxyphenyl)methane, and 1,1,2,2- diglycidyl ether or polyglycidyl ether of polyhydric phenols such as tetrakis(p-hydroxyphenyl)ethane; N- of amines such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, and N,N,N',N'-tetraglycidyl-bis-(p-aminophenyl)methane glycidyl derivatives; triglycidyl derivatives of aminopal; triglycidyltris(2-hydroxyethyl) isocyanurate, and triglycidyl isocyanurate; Epoxy resins, such as an ortho cresol-type epoxy resin and a phenol novolak-type epoxy resin, etc. 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 4.5 parts by mass, particularly preferably 0.5 to 100 parts by mass of the polyurethane polyol (A). 3.0 parts by mass.

(Antioxidant)

Examples of the antioxidant include a radical scavenger, a peroxide decomposing agent, and the like. As a radical scavenger, a phenol-type compound, an amine-type compound, etc. are mentioned. As the peroxide decomposing agent, a sulfur-based compound and a phosphorus-based compound may be cited.

Examples of the phenolic compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearin-β-(3,5- Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6- t-butyl phenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butyl phenol), 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]methane , bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl- 4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocophenol.

As phosphorus antioxidant, triphenylphosphite, diphenylisodecylphosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl)phosphite, cyclic neopentanetetra Ilbis(octadecylphosphite), tris(nonylphenyl)phosphite, tris(monononylphenyl)phosphite, tris(dinonylphenyl)phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro- 9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphape Nanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris(2,4-di-tert-butylphenyl)phosphite, cyclic neo Pentanetetraylbis(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl)phosphite, and 2,2-methylene and bis(4,6-di-tert-butylphenyl)octyl phosphite.

By using one or more antioxidants, it is possible to prevent thermal deterioration of the polyurethane polyol (A) and effectively suppress bleeding out of the plasticizer (P) in the adhesive layer.

The addition amount of one or more antioxidants is not specifically limited, Preferably it is 0.01-2.0 mass parts with respect to 100 mass parts of polyurethane polyol (A), More preferably, it is 0.1-1.5 mass parts, Especially preferably, 0.2 ~1.0 parts by mass.

As the antioxidant, it is preferable to use at least one phenolic compound as a radical scavenger from the viewpoint of stability and antioxidant effect, and it is more preferable to use at least one phenolic compound as a radical scavenger and at least one phosphorus compound as a peroxide decomposing agent in combination. desirable. Moreover, it is especially preferable to use together at least one type of phenolic compound which is a radical scavenger and at least one type of phosphorus compound which is a peroxide decomposing agent as antioxidant, and to use together these antioxidant and at least 1 type of hydrolysis-resistant agent mentioned above.

(Ultraviolet absorber)

Examples of the ultraviolet absorber include a benzophenone-based compound, a benzotriazole-based compound, a salicylic acid-based compound, an oxalic acid anilide-based compound, a cyanoacrylate-based compound, and a triadine-based compound.

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

(light stabilizer)

Examples of the light stabilizer include hindered amine compounds and hindered piperidine compounds. The amount of the at least one light stabilizer to be added is not particularly limited, and preferably 0.01 to 2.0 parts by mass, more preferably 0.1 to 1.5 parts by mass, particularly preferably 0.2 to 1.0 parts by mass relative to 100 parts by mass of the polyurethane polyol (A). is the mass part.

(leveling agent)

The urethane-based pressure-sensitive adhesive used in the present invention may include one or more leveling agents as needed. By adding at least one leveling agent to the urethane-based pressure-sensitive adhesive, the leveling property of the pressure-sensitive adhesive layer can be improved. Examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, and a silicone-based leveling agent. An acryl-type leveling agent etc. are preferable from a viewpoint of suppressing the to-be-adhered body contamination after peeling of an adhesive sheet again.

The weight average molecular weight (Mw) of a leveling agent in particular is not restrict|limited, Preferably it is 500-20,000, More preferably, it is 1,000-15,000, Especially preferably, it is 2,000-10,000. When Mw is 500 or more, there is very little vaporization amount in a coating layer at the time of heat-drying of a coating layer, and surrounding contamination is suppressed. When Mw is 20,000 or less, the improvement effect of the leveling property of an adhesive layer is expressed effectively.

The amount of one or more leveling agents added is not particularly limited, and from the viewpoint of suppressing adherend contamination after peeling off the adhesive sheet and improving the leveling property of the adhesive layer, preferably 0.001 to 2.0 with respect to 100 parts by mass of the polyurethane polyol (A). It is a mass part, More preferably, it is 0.01-1.5 mass part, Especially preferably, it is 0.1-1.0 mass part.

(Other optional ingredients)

The urethane-based pressure-sensitive adhesive used in the present invention may include one or more other additives, such as an antistatic agent, a silane coupling agent, a colorant, an antifoaming agent, a wetting agent, a weathering stabilizer, and a softener, if necessary.

[Adhesive layer]

The pressure-sensitive adhesive layer is made of a cured product of a urethane-based pressure-sensitive adhesive.

The probe tack of the adhesive layer is preferably 0.01 to 0.30 N/cm 2 , more preferably 0.02 to 0.25 N/cm 2 , particularly 0.05 to 0.2 N/cm 2 . An adhesive layer having a probe tag within this range has suitable adhesive strength and may have good adhesion to an adherend.

For example, the said adhesive force of an adhesion layer can be adjusted to a preferable range by adjusting the kind and quantity of the polyfunctional isocyanate compound (B) mix|blended with respect to a polyurethane polyol (A). 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 addition, in the present specification, the probe tack is measured by the method described in the item of [Example].

The preferred shear force of the adhesive layer is as follows.

The pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is attached to a glass plate with a contact area of 10 × 20 mm 2 , and the shear force when the pressure-sensitive adhesive sheet is peeled from the glass plate in a 180 degree direction at a peeling rate of 50 mm/min is preferably 5 to 25 N/cm 2 , more preferably 6 to 20 N/cm 2 , particularly preferably 7 to 15 N/cm 2 .

When the shear force is 5 N/cm 2 or more, the pressure-sensitive adhesive layer is not easily stretched, the adhesion of the pressure-sensitive adhesive sheet when adhered to the adherend is improved, and the positional adjustment and re-adhesion of the pressure-sensitive adhesive sheet when adhered to the adherend is facilitated. When the shear force is 25 N/cm 2 or less, it is suppressed that the pressure-sensitive adhesive layer is too elongated to cause the pressure-sensitive adhesive sheet to shift position after being adhered 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 shear force of the adhesive layer can be adjusted to a preferable range. . If the types of the polyurethane polyol (A) and the polyfunctional isocyanate compound (B) are the same, the shear force tends to increase as the amount of the polyfunctional isocyanate compound (B) increases. If the conditions of the polyurethane polyol (A) and the polyfunctional isocyanate compound (B) are the same, the shear force tends to decrease by adding the plasticizer (P). If the type of the plasticizer (P) is the same condition, the shear force tends to decrease as the amount of the plasticizer (P) increases.

In addition, in the present specification, the shear force shall be measured by the method described in the [Example] item.

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 in the prior art. The thickness of the pressure-sensitive adhesive layer can be appropriately designed according to the purpose of the pressure-sensitive adhesive sheet, and may be at a conventional level (5 to 30 µm) or a thick film level of 30 µm or more, which was difficult in the prior art. By thickening the adhesive layer, it is possible to form an adhesive layer having excellent impact resistance and a function of protecting an adherend from impact or the like. The upper limit of the thickness of the adhesive layer is not particularly limited, and an adhesive layer with good surface smoothness can be formed and is about 200 µm. From the viewpoint of improving impact resistance and surface smoothness, the thickness of the pressure-sensitive adhesive layer is preferably 30 to 200 µm, more preferably 40 to 150 µm, and particularly preferably 50 to 150 µm. In addition, in this specification, the "thickness of an 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 sheet and an adhesive layer composed of a cured product of a urethane pressure-sensitive adhesive. The adhesive layer may be formed on one or both surfaces of the base sheet. If necessary, the exposed surface of the adhesive layer may be coated with a release sheet (also referred to as a release liner). Further, the release sheet is peeled off when the pressure-sensitive adhesive sheet is adhered to the adherend.

Schematic sectional drawing of the adhesive sheet of 1st - 3rd embodiment which concerns on this invention to FIG. 1-3 is shown. 1 to 3, reference numerals 10X, 10Y, and 10Z denote an adhesive sheet, reference numeral 11 denotes a base sheet, reference numeral 12 denotes an adhesive layer, and reference numeral 13X, 13Y, and 13Z denote a release sheet. All of 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 sheet. In addition, like reference numerals are attached to the same components in FIGS. 1 to 3 .

(Reference sheet)

The base sheet 11 may be a single-layer sheet composed of the sheet main body 11A, or may be a laminated sheet in which one or more layers are laminated on at least one surface of the sheet main body 11A. From the standpoint of antistatic of the adhesive sheets 10X, 10Y, and 10Z, the base sheet 11 preferably includes a sheet body 11A and an antistatic layer 11B formed on the non-formed side surface of the adhesive layer 12. do. 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 main body 11A is not particularly limited, and can be a resin sheet, paper, metal foil, or the like, and a resin sheet is preferable.

It does not restrict|limit especially as structural resin of a resin sheet, Ester-type resin, such as polyethylene terephthalate (PET); olefin resins such as polyethylene (PE) and polypropylene (PP); vinyl-based resins such as polyvinyl chloride; amide resins such as nylon 66; urethane-based resins (including foams); Combinations of these may be cited. As the sheet main body 11A, a PET sheet or the like is preferable.

The thickness in particular of the resin sheet except a polyurethane sheet is not restrict|limited, Preferably it is 15-300 micrometers. The thickness of the polyurethane sheet (including foam) is not particularly limited and is preferably 20 to 50,000 μm.

Since the adhesive layer 12 excellent in surface smoothness can be formed, the arithmetic mean roughness Ra of the sheet main body 11A is preferably 0.7 µm or less, more preferably 0.5 µm or less, particularly preferably 0.2 µm or less. to be.

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, particularly preferably 2% or less.

The antistatic layer 11B contains one or more types of antistatic agents AS. As the antistatic agent (AS), a known agent can be used, and a surfactant (SF), a conductive polymer (EP), and the like can be cited.

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

Examples of the nonionic low molecular surfactant include glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamine fatty acid ester, fatty acid diethanolamide, and the like. can be pointed out

Examples of the anionic low-molecular surfactant include alkylsulfonates, alkylbenzenesulfonates, and alkylphosphates.

As a cationic low molecular surfactant, a tetraalkyl ammonium salt, a trialkyl benzyl ammonium salt, etc. are mentioned.

Examples of the amphoteric low molecular surfactant include alkyl betaine and alkylimidazolinium 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 salt-containing acrylate polymer type.

Examples of the amphoteric polymer surfactants include amino acid type amphoteric surfactants such as higher alkyl amino propionate, betaine type amphoteric surfactants such as higher alkyl dimethyl betaine and higher alkyl dihydroxyethyl betaine.

Examples of the conductive polymer (EP) used as the antistatic agent (AS) include polyacetylene, polyaniline, polythiophene, polypyrrole, polyphenylene sulfide, poly(1,6-heptadiene), and polybiphenylene (polyparaphenylene). ), polyparaphenylene sulfide, polyphenylacetylene, poly(2,5-thienylene), and derivatives thereof.

As the antistatic agent (AS), a conductive polymer (EP) is preferable.

In general, the pressure-sensitive adhesive sheet may become cloudy (whitening) when exposed to a high-temperature, high-humidity environment. The conductive polymer (EP) has lower hydrophilicity compared to the surfactant (SF), and by using one or more conductive polymers (EP) as the antistatic agent (AS), the antistatic layer 11B becomes less affected by humidity, thereby suppressing moist heat whitening. You might think you can do it.

In addition, as an index of hydrophilicity, a water contact angle can be cited. 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 elapsed after water is dropped on the surface of the antistatic layer. to be.

1 to 3 , the release sheets 13X, 13Y, and 13Z include a sheet main body 13A and a release agent layer 13L formed on the surface of the adhesive layer 12 side thereof. As shown in FIGS. 2 and 3 , from the viewpoint of preventing the adhesive sheet from being charged, the release sheets 13Y and 13Z may further include an antistatic layer 13B formed on the surface opposite to the adhesive layer 12 . As shown in FIG. 3 , the release sheet 13Z may further include an antistatic layer 13B between the sheet main body 13A and the release agent layer 13L from the viewpoint of improving the antistatic properties of the pressure-sensitive adhesive sheet.

As the sheet main body 13A, a resin sheet, paper, or the like can be cited.

The release agent layer 13L contains one or more types of release agents, such as a silicone resin.

The at least one antistatic agent used for the antistatic layer 13B is the same as the antistatic layer 11B of the base sheet 11 described above. It is preferable that the antistatic layer 13B contains 1 or more types of conductive polymer (EP) from a viewpoint of moist-heat-resistance whitening improvement. Like the antistatic layer 11B, the antistatic layer 13B preferably has a water contact angle of 40 to 110 degrees after 1000 ms has elapsed after water is dripped onto the surface of the antistatic layer 13B.

The pressure-sensitive adhesive sheets 10X, 10Y, and 10Z can be manufactured by a known method.

First, a urethane-based pressure-sensitive adhesive is applied to the surface of the base sheet 11 to form a coating layer composed of the urethane-based pressure-sensitive adhesive. As the coating method, a known method may be applied, and a roll coater method, a comma coder method, a die coater method, a reverse coater method, a silk screen method, and a gravure coder method may be cited.

Next, the coating layer is dried and cured to form a pressure-sensitive adhesive layer containing a cured product of a urethane pressure-sensitive adhesive. The heat drying temperature is not particularly limited and is preferably about 60 to 150°C.

Next, the release sheets 13X and 13Y are pasted on the exposed surface of the adhesive layer 12 by a known method if necessary.

As described above, the pressure-sensitive adhesive sheets 10X, 10Y, and 10Z can be manufactured.

Conversely to the above method, a urethane-based adhesive is coated on the surface of the release sheets 13X, 13Y, and 13Z to form a coating layer composed of a urethane-based adhesive, and then the coating layer is dried and cured to form an adhesive layer containing a cured product of the urethane-based adhesive ( 12), and finally, the base sheet 11 may be laminated on the exposed surface of the adhesive layer 12 .

The prepared pressure-sensitive adhesive sheets 10X, 10Y, and 10Z may be preferably wound on a core to form a pressure-sensitive adhesive sheet roll. Moreover, an uncured material may remain in the adhesive layer 12 at this time, and it is preferable to cure an adhesive sheet roll for a certain period of time.

(purpose)

The adhesive sheet of this invention can be used in forms, such as a tape, a label, and a seal|sticker. The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protection sheet, a cosmetic sheet, an anti-slip sheet, and the like.

BACKGROUND ART Flat panel displays such as liquid crystal displays (LCDs), and touch panel displays in which a related flat panel display and touch panel are combined, are widely used in electronic devices such as televisions (TVs), personal computers (PCs), mobile phones, and portable information terminals. have.

The pressure-sensitive adhesive sheet of the present invention is suitably used as a surface protection sheet for flat panel displays and touch panel displays, and for substrates and optical members manufactured or used in their manufacturing processes.

As described above, according to the present invention, in the manufacturing process, the coating layer composed of the urethane-based adhesive can be cured relatively quickly, and an adhesive layer having a good surface appearance can be formed, and the adhesive layer can be thickened if necessary. Sheets can be provided.

In the manufacturing process of the adhesive sheet, when the coating layer is cured relatively quickly, the coating layer and the adhesive layer are affected by hot air during heat drying of the coating layer or mechanical stress received when the pressure sensitive adhesive sheet obtained after heat drying is carried out. difficult. Therefore, occurrence of defects such as wick step marks, orange peel, and winding habit of the adhesive layer is suppressed, and an adhesive sheet having an adhesive layer having a good surface appearance can be manufactured.

When the coating layer cures relatively quickly, it is easy to apply a thick film of the pressure-sensitive adhesive. Since the adhesive layer can be thickened, it is possible to form an adhesive layer having excellent cushioning properties and excellent performance (impact resistance, etc.) for protecting adherends such as various optical members from impacts.

When 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 the at least one polyol (x), which is a raw material for the polyurethane polyol (A), contains at least one difunctional polyol.

When the urethane-based pressure-sensitive adhesive contains at least one plasticizer (P), and the at least one plasticizer (P) contains at least one EO group-containing organic acid ester, the hydrophilicity of the pressure-sensitive adhesive layer is improved to prevent moist heat and whitening of the pressure-sensitive adhesive layer. can be improved

When the base sheet of the pressure-sensitive adhesive sheet includes an antistatic layer, it is preferable that the pressure-sensitive adhesive sheet has antistatic properties. In addition, when the antistatic layer contains one or more conductive polymers (EP), the antistatic layer is less affected by humidity, so that the moisture-and-heat resistance whitening of the adhesive layer can be improved.

[Example]

Hereinafter, synthesis examples, examples related to the present invention, and comparative examples will be described.

[Evaluation items and evaluation methods of various physical properties]

(weight average molecular weight (Mw))

The weight average molecular weight (Mw) was measured by the gel permeation chromatography (GPC) method. The measurement conditions are as follows. In addition, Mw is a polystyrene conversion value.

<Measurement conditions>

Device: SHIMADZU Prominence (manufactured by Shimadzu Corporation)

Column: three TOSOH TSK-GEL GMHXL (manufactured by Tosoh Corporation) are connected in series;

Solvent: tetrahydrofuran

Flow rate: 0.5ml/min

Solvent temperature: 40℃

Sample concentration: 0.1% by mass

Sample injection volume: 100 μl

(viscosity)

The viscosity was measured on condition of the following based on JISZ8803.

Apparatus: Type B viscometer TVB10M (Togi Sangyo Co., Ltd.)

Rotor: No.3

RPM: 12rpm,

Measuring temperature: 25℃

(hydroxyl value)

The hydroxyl value was measured by the neutralization titration method based on JISK0070.

First, 25 g of acetic anhydride was put into a 100 ml flask, and pyridine was added thereto to make the total amount 100 ml. The contents were sufficiently shaken to prepare an acetylation reagent. The obtained acetylation reagent was stored in a brown bottle so as not to come into contact with moisture, carbon dioxide, and acid vapor.

Then, the sample was placed in a flask with a flat bottom, 5 ml of the above acetylation reagent was added thereto using a pipette, and a small funnel was installed in the mouth of the flask. The bottom of this flask (a portion about 1 cm high 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 with a round hole in the center was covered with a place where the neck of the flask was attached. After 1 hour from the start of the glycerin bath heating, the flask was taken out of the glycerin bath and cooled. 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 completely decompose acetic anhydride, in the same manner as above, the bottom of the flask was heated again in a glycerin bath for 10 minutes, and then the flask was taken out of the glycerin bath and cooled. Then, 5 ml of ethanol was fed 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.

Then, a few drops of phenolphthalein solution as an indicator were added into the flask, titrated using 0.5 mol/l potassium hydroxide ethanol solution, and the time point when the pale red color of the indicator continued for about 30 seconds was set as the end point.

Separately, a blank test in which the same operation as above was performed without putting the sample in the flask was conducted.

The hydroxyl value of the polyurethane polyol (A) (solid content) was computed by following formula (1).

A=((B-C)×f×28.05/S)/(Non-volatile matter concentration/100)+D… (One)

(However, in the formula (1), A: hydroxyl value (mgKOH/g), B: 0.5 mol/l potassium hydroxide ethanol solution amount (ml) used for blank test, C: 0.5 mol/ used for titration l Amount of potassium hydroxide ethanol solution (ml), f: 0.5 mol/l potassium hydroxide ethanol solution factor (concentration correction factor), S: mass of sample (g), D: acid value (mgKOH/g))

In this specification, a hydroxyl value may be abbreviate|omitted and described with "OH number".

[Reference sheet]

The base sheet used is as follows.

<Base sheet (SH-1)>

A polyethylene terephthalate (PET) sheet (ester film E5100, corona-treated on one surface, manufactured by Toyobo) having a thickness of 50 µm was prepared as a sheet body, and this was used as it is as a base sheet (SH-1).

<Base sheet (SH-2)>

As a conductive polymer (EP-1), a dispersion liquid (Enocoat BP105, manufactured by Kaken Sangyo Co., Ltd.) containing conductive polythiophene was prepared. This conductive polythiophene dispersion was diluted with propanol to obtain an antistatic coating agent (ASC-1) (non-volatile matter (NV) 1% by mass). A base sheet (SH-1) was prepared as the sheet body. The antistatic coating agent (ASC-1) was coated on the corona-treated surface of the sheet body by a bar coater method and dried in an oven at 80° C. for 3 minutes to form an antistatic layer with a thickness of 0.5 μm. As mentioned above, the base material 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 an antistatic coating agent (ASC-2) as it was. Except having used this antistatic coating agent, the base material sheet (SH-3) with an antistatic layer was obtained by the same method as manufacture of the base material sheet (SH-2).

[ingredient]

Materials used in Synthesis Examples, Examples, and Comparative Examples are as follows.

<Polyol (x)>

(x-1): Kuraray polyol P1010 (polyester diol, OH number 112, molecular weight 1,000, Kuraray Co., Ltd. product),

(x-2) F2010: Kuraray polyol F2010 (polyester triol, OH number 84, molecular weight 2,000, Kuraray Co., Ltd. product),

(x-3) PP2000: Sunnics PP-2000 (polyetherdiol, OH number 56, molecular weight 2,000, Sanyo Kasei Kogyo Co., Ltd. product),

(x-4) G3000B: ADEKA polyol G3000B (polyether triol, OH number 56, molecular weight 3,000, ADEKA Co., Ltd. product).

<Polyisocyanate (y)>

(y-1): Death module H (hexamethylene diisocyanate, Sumika Covestro Urethane Co., Ltd. product).

<Metal containing catalyst (MC)>

(MC-1): di-n-butyl tin 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 (the isocyanurate form of hexamethylene diisocyanate, non-volatile matter (NV) 100 mass %, NCO group amount 21 mol%, Tosoh Co., Ltd. product).

<Plasticizer (P)>

(P-1): Monosizer W262 (polyether ester plasticizer, EO group-containing, nonvolatile matter (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 matter (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 four-neck flask equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, a thermometer, and a dropping fennel, under a nitrogen atmosphere, 100 parts by mass of polyol (x-1), 15.5 parts by mass of polyisocyanate (y-1), toluene 77 parts by mass and 0.02 parts by mass of the metal-containing catalyst (MC-1) were prepared. The flask was gradually heated and the reaction was carried out at about 90°C for 2 hours. Thereafter, the reaction was continued while confirming whether the residual isocyanate group disappeared by infrared absorption (IR) spectrum, and after confirming the disappearance, the flask was immediately cooled to terminate the reaction. Finally, toluene was added so that a non-volatile matter (NV) might be 60 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 results of evaluation of the physical properties of the polyurethane polyol (A-1) solution obtained by the blending composition. In addition, in Table 1, 2f shows bifunctionality and 3f shows trifunctionality. In Table 1, the unit of the compounding quantity of each material is [mass part]. In Table 1, the quantity (unit is mass part) of the metal containing catalyst (MC) with respect to 100 mass parts of polyurethane polyols (A) in a solution is also shown collectively.

(Synthesis Examples 2 to 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 mixing composition of the raw materials was changed to be shown in Table 1. In each synthesis example, Table 1 shows the results of evaluation of the physical properties of the solution of the obtained polyurethane polyol.

[Example 1]

With respect to the solution of the polyurethane polyol (A-1) obtained in Synthesis Example 1, various materials were blended. The quantity of the polyurethane polyol (A-1) in a solution was 100 mass parts. On the other hand, 5.4 parts by mass of the polyfunctional isocyanate compound (B-1), 0.150 parts by mass of an additive (R- 6 mass parts of 1) and 5 mass parts of ethyl acetate were mix|blended as a solvent. A urethane-type adhesive was obtained by stirring these materials with a disper. The obtained urethane-based pressure-sensitive adhesive was directly used for evaluation of pot life. Moreover, the obtained urethane-type adhesive was used for evaluation of thick-film coatability.

As the base sheet, a base sheet (SH-2) provided with an antistatic layer was prepared. The urethane-based pressure-sensitive adhesive obtained by using a doctor blade was coated on the surface of the base sheet on which the antistatic layer was not formed so that the thickness after drying was set to 50 µm. The formed coating layer was dried at 120 degreeC for 4 minutes, and the adhesion layer was formed. A 25-micrometer-thick peeling sheet (250010BD, Fuji Morikogyo make) was pasted on this adhesive layer, and the adhesive sheet was obtained. The obtained pressure-sensitive adhesive sheet was cured under the conditions of 23°C-50%RH for 1 week, and then used for other evaluations.

[Examples 2 to 12, Comparative Examples 1 to 5]

In Examples 2 to 12 and Comparative Examples 1 to 5, the urethane pressure-sensitive adhesive and the pressure-sensitive adhesive sheet were obtained and evaluated in the same manner as in Example 1 except that the base sheet used as the compounding composition of the urethane pressure-sensitive adhesive was changed to that shown in Table 2 did.

In addition, in Table 2, the unit of the compounding quantity of each material is [mass part]. 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 total amount of the metal-containing catalyst (MC) contained in the solution of the polyurethane polyol (A) obtained in the synthesis example and the metal-containing catalyst (MC) newly added in the Examples or Comparative Examples . In addition, 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 groups (OH) in the polyurethane polyol (A) (NCO/OH functional group) b) is also shown.

[Evaluation items and evaluation methods of adhesives and pressure-sensitive adhesive sheets]

Evaluation items and evaluation methods of the urethane-based pressure-sensitive adhesive and the pressure-sensitive adhesive sheet are as follows (pot life).

The obtained urethane pressure-sensitive adhesive was placed in a glass bottle with a lid immediately after production, the glass bottle was placed in a constant temperature water bath at 25° C., and the viscosity of the urethane pressure-sensitive adhesive after 1 hour and 12 hours from the start of the introduction was measured, respectively. The viscosity increase rate after 12 hours (viscosity after 12 hours / viscosity [fold] after 1 hour) with respect to 1 hour was calculated. The evaluation criteria are as follows.

<Evaluation criteria>

○: Viscosity increase rate is less than 2 times (excellent),

△: Viscosity increase rate is more than 2 times but less than 3 times (good),

x: The viscosity increase rate is 3 times or more (there is a problem practically).

(thick film coatability)

As the base sheet, a polyethylene terephthalate (PET) sheet (Lumira T-60, manufactured by Toray) having a width of 430 mm and a thickness of 100 µm was prepared. A pressure-sensitive adhesive sheet was manufactured by a roll-to-roll process using a test manufacturing apparatus (Commercoater: Registered Trademark).

The conveyance speed of the base material sheet was 1.0 m/min. On one side of the base sheet, the obtained urethane-based pressure-sensitive adhesive was coated with a width of 400 mm so that the thickness after drying was set to 150 µm to form a coating layer. Then, this sheet was passed through an oven set at 130° C. with a length of 4 m to dry and harden the coating layer. Next, a release sheet (250010BD, manufactured by Fuji Morocco) having a width of 430 mm and a thickness of 25 µm was pasted on the formed adhesive layer. Next, the obtained adhesive sheet was wound around a core (6-inch ABS core) with a length of 100 m. The obtained pressure-sensitive adhesive sheet roll was cured under the conditions of 23°C-50%RH for one week.

Before curing, in the obtained adhesive sheet roll, a test piece having a size of 400 mm in width and 500 mm in length was cut out at a position of 1 m from the end of the winding end side (outside) of the adhesive sheet, and the following evaluation was performed.

After curing, from the obtained pressure-sensitive adhesive sheet roll, a test piece having a size of 400 mm in width and 500 mm in length was cut out at a position 10 m long from the end of the winding start side (inner side, core side) of the pressure-sensitive adhesive sheet, and the following evaluation was performed.

(1) Evaluation before curing (initial hardenability):

The thickness of the test piece was measured using a dial gauge. The evaluation criteria are as follows.

<Evaluation criteria>

(double-circle): The adhesive layer is fully hardened, and the thickness of an adhesive sheet can be measured accurately (good).

(circle): Although the adhesive layer is slightly soft, the thickness of an adhesive sheet can be measured (there is no problem practically).

x: There exists fluidity in an adhesive layer, and the thickness of an adhesive sheet cannot be measured (there exists a problem practically).

(2) Evaluation after curing (surface appearance):

The test piece was illuminated with a fluorescent lamp, and the surface appearance of the test piece was visually evaluated. The evaluation criteria are as follows.

<Evaluation criteria>

◎: no orange peel and wick step marks (good);

○: Orange peel and/or wick step marks are slightly visible (no problem in practice),

×: Orange peel and/or wick step marks are seen (there is a practical problem).

(Adhesiveness 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 23 degreeC-50%RH atmosphere, and the surface of the exposed adhesive layer was stuck to the glass plate. When pasting on a glass plate, it was judged as "defect" that wrinkles were formed in an adhesive sheet, a bubble entered in a sticking interface, or other parts of an adhesion layer closely_contact|adhered to each other. This evaluation was performed 10 times. The evaluation criteria are as follows.

<Evaluation criteria>

◎: 0 times (good)

○: 1 to 2 times the number of defects (no problem in practice)

×: The number of defectives is 3 or more (there is a problem in practice)

(adhesion 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 in an atmosphere of 23° C.-50% RH, the exposed surface of the adhesive layer was attached to a glass plate, and a 2 kg roller was reciprocated once on the pressure-sensitive adhesive sheet to press and leave them for 24 hours. Then, using the tensile tester, the 90 degree peeling test of the adhesive sheet was implemented at the peeling rate of 0.3 m/min, and adhesive force was measured. Generally, it can be said that the one which has low adhesive force with glass and is easily re-peelable has high practicality as a surface protection use.

(probe tag)

A test piece having a width of 30 mm and a length of 30 mm was cut out from the adhesive sheet. Next, the release sheet was peeled off from the test piece in 23 degreeC-50%RH atmosphere, and the probe tack of the surface of the exposed adhesive layer was measured based on JIS Z0237. As the device, a probetack measuring device (manufactured by Tester Sangyo Co., Ltd.) was used. A stainless steel probe (20 g) having a diameter of 5 mmφ was brought into contact with the surface of the adhesive layer for 1 second under a contact load of 1.0 N/cm 2 , and then the probe was removed 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 performed 3 times, and the average value was calculated|required.

(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 of 20 mm from one end in the longitudinal direction, and the area from one end to the marked line (a region of 10 mm in width and 20 mm in length) is used as the test area. did Under 23°C-50%RH atmosphere, the release sheet was peeled from the test piece, the test area of the surface of the exposed adhesive layer was affixed to a glass plate, and a 2 kg roller was reciprocated once on the adhesive sheet, and then they were pressed. Thereafter, using a tensile tester, the test piece and the glass plate were pulled in 180° opposite directions to each other under the condition of a peeling rate of 50 mm/min, and the shear force was measured. The measurement was performed 5 times, and the average value was calculated|required.

(Water contact angle on the surface of the adhesive layer)

A test piece with 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 in 23 degreeC-50%RH atmosphere, and the water contact angle of the surface of the exposed adhesive layer was measured. As an apparatus, DM-501 manufactured by Kyowa Interface Science Co., Ltd. was used, and the water contact angle was measured after 61000 ms had elapsed after water was dripped onto the surface of the adhesive layer. In addition, the value computed by the (theta)/2 method was made into the measured value. The measurement was performed 5 times, and the average value was calculated|required.

(Water contact angle on the non-formation side surface 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. Then, the water contact angle of the surface of the base sheet on which the adhesive layer was not formed was measured under 23°C-50%RH atmosphere. As a device, DM-501 manufactured by Kyowa Interface Science Co., Ltd. was used, and the water contact angle was measured after 1000 ms of dripping water. In addition, the value computed by the (theta)/2 method was made into the measured value. The measurement was performed 5 times, and the average value was calculated|required.

(Moisture Heat Whitening Resistance)

Two test pieces with a width of 25 mm and a length of 100 mm were cut out from the adhesive sheet.

As for one test piece, haze evaluation was performed (there is no progress of wet heat). The other test piece was left to stand in a 60 degreeC-95%RH atmosphere for 48 hours, returned to room temperature atmosphere (20-25 degreeC), and after cooling sufficiently, haze evaluation was performed (wet heat progress exists). About both test pieces, the release sheet was peeled from the test piece in 23 degreeC-50%RH atmosphere, and the haze was measured based on JISK7165 in the state which the adhesive layer was exposed. As the device, a Turbidimeter NDH5000W (manufactured by Nippon Denshoku Co., Ltd.) was used. A D65 light source was used as the light source. ΔH was calculated based on the following equation. The evaluation criteria are as follows.

ΔH=Hb-Ha

(wherein, Ha is the haze of the test piece without moist heat progress, and Hb is the haze of the test piece with wet heat progress)

<Evaluation criteria>

◎: ΔH less than 2.0 (good),

○: 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: ?H is 4.0 or more (there is a problem practically).

[Evaluation results]

Table 3 shows the evaluation results.

In Examples 1 to 12, a polyurethane polyol (A) which is a copolymerization reaction product of at least one polyol (x) and at least one polyisocyanate (y), a polyfunctional isocyanate compound (B), and a polyurethane polyol (A) ) A urethane-based adhesive containing 0.08 to 0.70 parts by mass of a metal-containing catalyst (MC) was prepared with respect to 100 parts by mass, and an adhesive sheet including an adhesive layer having a thickness of 50 μm was prepared using this.

All of the urethane-based pressure-sensitive adhesives obtained in Examples 1 to 12 had good or relatively good evaluation results of pot life. In Examples 1 to 12, even when thick film coating was applied, the coating layer was able to form an adhesive layer having excellent initial curability or good surface appearance after curing.

All of the adhesive sheets obtained in Examples 1 to 12 had excellent or good evaluation results of adhesion to glass, adhesive force to glass, probe tack, and shear force, and generally required performance as an adhesive sheet was excellent or good. In particular, the adhesive sheets obtained in Examples 2 to 10 using the plasticizer (P) had excellent performances.

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

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

In Comparative Example 2, a base material sheet including an antistatic layer containing a conductive polymer (EP) was used using a plasticizer (P) containing at least one EO group, but the pressure-sensitive adhesive sheet obtained by using only an amine catalyst as a catalyst was The whitening resistance of moisture and heat was poor.

In Comparative Example 3, the polyurethane polyol (A) was not used, so the initial curability of the coating layer was insufficient, and the thick film coating property was poor. The obtained pressure-sensitive adhesive sheet had poor adhesion to glass, adhesive force to glass, probe tack, and poor shear force evaluation results. The heat-and-moisture whitening 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 comprised of the obtained urethane-type adhesive did not harden|cure in a heating process, but was not able to form an adhesion layer.

[Table 1]

[Table 2]

[Table 3]

This invention is not limited to the said embodiment and an Example, A design change is possible as long as it does not deviate from the meaning of this invention.

10X, 10Y, 10Z; adhesive sheet
11; base material sheet
11A; seat body
11B; antistatic layer
12; adhesive layer
13X, 13Y, 13Z; release sheet
13A; seat body
13B; antistatic layer
13L; release agent layer

Claims (10)

It is a pressure-sensitive adhesive sheet having re-peelability, comprising a base sheet and an adhesive layer composed of a cured product of a urethane pressure-sensitive adhesive formed on one side of the base sheet,
The urethane-based pressure-sensitive adhesive,
A polyurethane polyol (A) which is a copolymerization reaction product of at least one polyol (x) and at least one polyisocyanate (y);
A polyfunctional isocyanate compound (B), and
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);
comprising at least one plasticizer (P),
At least one plasticizer (P) contains an organic acid ester having at least one ethyleneoxy group in one molecule,
The pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer has a water contact angle of 40 to 80° after 61000 ms has elapsed after water is dripped onto the surface of the pressure-sensitive adhesive layer.

According to claim 1,
An adhesive sheet having a probe tack of the adhesive layer of 0.01 to 0.30 N/cm 2 .
3. The method of claim 1 or 2,
When the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is attached to a glass plate with a contact area of 10×20 mm 2 A pressure-sensitive adhesive sheet of ~25N/cm2.
3. The method of claim 1 or 2,
The pressure-sensitive adhesive sheet wherein the amount of the at least one polyester polyol is 50 to 100% by mass relative to the total amount of the at least one polyol (x).
5. The method of claim 4,
The pressure-sensitive adhesive sheet wherein the amount of the at least one bifunctional polyester polyol is 20 to 100% by mass relative to the total amount of the at least one polyester polyol.
3. The method of claim 1 or 2,
The base sheet is an adhesive sheet comprising a sheet body and an antistatic layer formed on a surface of the sheet body on which the adhesive layer is not formed.
7. The method of claim 6,
The antistatic layer is an adhesive sheet comprising a conductive polymer.
3. The method of claim 1 or 2,
An adhesive sheet having a thickness of the adhesive layer of 30 to 200 μm.
3. The method of claim 1 or 2,
Adhesive sheet for surface protection.
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