KR102434160B1 - UV-curable adhesive sheet and adhesive sheet - Google Patents

Abstract

The problem to be solved by the present invention is to provide an ultraviolet curable pressure-sensitive adhesive sheet that is excellent in step followability, sheet retention, and moisture-heat resistance and whitening resistance, and does not leave glue on the blade when cutting. The present invention provides an acrylic resin (A) having a hydroxyl group and/or a carboxyl group, a crosslinking agent (B), a (meth)acrylic compound (C) having two or more (meth)acryloyl groups, an organic solvent (D), and, It is an ultraviolet curable pressure-sensitive adhesive sheet obtained by coating a pressure-sensitive adhesive composition containing a photopolymerization initiator (E) on a release paper and drying the organic solvent (D), measured at a temperature of 20° C. and a frequency of 10 ^-7 Hz One storage modulus is to provide an ultraviolet curable pressure-sensitive adhesive sheet, characterized in that it exceeds 5×10 ³ Pa and is less than or equal to 1×10 ⁵ Pa.

Description

UV-curable adhesive sheet and adhesive sheet

This invention relates to the ultraviolet curing adhesive sheet which can be used suitably for manufacture of an IT-related product.

A touch panel is installed in a mobile terminal such as a smart phone or a tablet, and the touch panel is composed of a laminate of a cover glass, an electrode glass/film, and a liquid crystal panel, which is an adhesive sheet (Optical Clear Adhesive, Hereinafter, it is abbreviated as "OCA"). In a smart phone, a decorative layer is provided on the cover glass and a step of about 20 µm is formed, so it is necessary for the OCA to adhere to the cover glass while following the step.

In recent years, along with the increase in the design of the smart phone, the decorative layer is thickened to about 60 μm (厚膜化). In addition, since the tablet-type terminal has a large screen, the deformation is large, and the OCA is required to have a performance capable of following a thicker step or deformation. In particular, from the viewpoint of designability, in order to enable both the thickness reduction of the entire portable terminal and the thickness reduction of the decorative layer, the performance of following a large step difference without thickening the OCA is required.

As an ultraviolet curable adhesive composition usable for the said OCA, the adhesive obtained using the solvent-free adhesive composition containing, for example, urethane acrylate, an acrylic monomer, and a photoinitiator is known (for example, refer patent document 1) ).

However, in the method of reducing the crosslinking density of the resin and imparting flexibility as in the above-mentioned adhesive, the step followability is good, but if the adhesive is too soft, it will flow during heating, leading to entrainment of air bubbles or extrusion of the adhesive. There was a problem that the non-uniformity of the thickness and the like occurred.

Japanese Patent Laid-Open No. 2006-104296

The problem to be solved by the present invention is to provide an ultraviolet curable pressure-sensitive adhesive sheet that is excellent in step followability, sheet retention, and moisture-heat resistance and whitening resistance, and does not leave glue on the blade when cutting.

The present invention provides an acrylic resin (A) having a hydroxyl group and/or a carboxyl group, a crosslinking agent (B), a (meth)acrylic compound (C) having two or more (meth)acryloyl groups, an organic solvent (D), and, A UV-curable pressure-sensitive adhesive sheet obtained by coating a pressure-sensitive adhesive composition containing a photopolymerization initiator (E) on release paper and drying the organic solvent (D), wherein the UV-curable pressure-sensitive adhesive sheet is measured at a temperature of 20°C and a frequency of 10 ^-7 Hz One storage modulus is to provide an ultraviolet curable pressure-sensitive adhesive sheet, characterized in that it exceeds 5×10 ³ Pa and is less than or equal to 1×10 ⁵ Pa.

Moreover, this invention provides the adhesive sheet obtained by ultraviolet-curing the said ultraviolet curable adhesive sheet, The adhesive sheet characterized by the above-mentioned.

The ultraviolet curing adhesive sheet of this invention is excellent in step|step difference followable|trackability, sheet holding property, and moisture-heat-resistance whitening property, and does not leave glue on the blade at the time of a blanking process (hereafter abbreviated as "die-cut property"). Therefore, the ultraviolet curable pressure-sensitive adhesive sheet of the present invention can be suitably used as an optical member, and in particular, can be suitably used for manufacturing IT-related products such as touch panels, liquid crystal displays, plasma displays, organic EL, computers, and mobile phones. have.

The ultraviolet curable adhesive sheet of the present invention comprises an acrylic resin (A) having a hydroxyl group and/or a carboxyl group, a crosslinking agent (B), a (meth)acrylic compound (C) having two or more (meth)acryloyl groups, an organic solvent ( D), and coating the pressure-sensitive adhesive composition containing the photopolymerization initiator (E) on release paper, and drying the organic solvent (D), the storage elastic modulus measured under the conditions of a temperature of 20 ° C. and a frequency of 10 ^-7 Hz, Exceeding 5×10 ³ Pa and less than or equal to 1×10 ⁵ Pa.

When the elastic modulus measured under the conditions of a temperature of 20 ° C. and a frequency of 10 ^-7 Hz of the UV-curable pressure-sensitive adhesive sheet is 5×10 ³ Pa or less, the pressure-sensitive adhesive is very flexible and the initial adhesiveness is too high. Since the pressure-sensitive adhesive sheet cannot maintain its shape when the blade and the pressure-sensitive adhesive come into contact, the die-cut property is poor, and when it exceeds 1×10 ⁵ Pa, the adhesive force becomes very weak, so the pressure-sensitive adhesive at the interface with the separator is easy to slip, and since the blanking position cannot be fixed, the die-cut property becomes poor. The elastic modulus of the UV-curable pressure-sensitive adhesive sheet is more preferably in the range of 6×10 ³ to 5×10 ⁴ Pa from the viewpoint that the die-cut property is further improved by being able to impart appropriate flexibility and adhesiveness to the pressure-sensitive adhesive. do.

The acrylic resin (A) having a hydroxyl group and/or a carboxyl group is an essential component for thermally crosslinking with a crosslinking agent (B) described later to express excellent sheet retention. As said acrylic resin (A), For example, (meth)acrylic acid alkylester (a-1), (meth)acrylic compound (a-2) which has a hydroxyl group, and/or (meth)acrylic compound which has a carboxyl group ( What is obtained by superposing|polymerizing the (meth)acrylic compound (a) which has a-3) as an essential component can be used.

The number of carbon atoms in the alkyl group of the (meth)acrylic acid alkyl ester (a-1) is preferably in the range of 1 to 20, and in the range of 2 to 12, from the viewpoint of easiness of raw material availability and good adhesive strength. It is more preferable, and the range of 4-8 is still more preferable.

As a specific example of the said (meth)acrylic acid alkylester (a-1), For example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate ) acrylate, t-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, Isodecyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, glycidyl (meth)acrylate, etc. are mentioned. These compounds may be used independently or may use 2 or more types together. Among these, it is preferable to use n-butyl (meth)acrylate and/or 2-ethylhexyl (meth)acrylate from the point of polymerizability and adhesive force. Moreover, since it is easy to adjust the glass transition temperature of an acrylic resin (A) with a high glass transition temperature, and it is easy to provide cohesive force by a ring structure, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate It is preferable to use at least one compound selected from the group consisting of , dicyclopentanyl (meth)acrylate, and dicyclopentanyloxyethyl (meth)acrylate.

As the usage-amount of the said (meth)acrylic-acid alkylester (a-1), it is preferable that it is the range of 50-99.5 mass % in the said (meth)acrylic compound (a) from a point from which favorable adhesive force is obtained, and 60-97 mass % is more preferable.

As a (meth)acrylic compound (a-2) which has the said hydroxyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, Acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxy Oxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate, glycerol (meth)acrylate, etc. can be used. These compounds may be used independently or may use 2 or more types together.

As the usage-amount in the case of using the (meth)acrylic compound (a-2) which has the said hydroxyl group, the said (meth)acrylic compound forms a favorable crosslinking reaction with a crosslinking agent (C), and favorable adhesive force and sheet retention are obtained. It is preferable that it is the range of 0.001-20 mass % in (a), and the range of 0.01-5 mass % is more preferable.

As (meth)acrylic compound (a-3) which has the said carboxyl group, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, etc. can be used, for example. These compounds may be used independently or may use 2 or more types together. Among these, in adjusting the glass transition temperature of an acrylic resin (A), it is preferable to use (meth)acrylic acid from the point which has the outstanding cohesion force derived from a high glass transition temperature.

As the usage-amount in the case of using the (meth)acrylic compound (a-3) which has the said carboxyl group, the said (meth)acrylic compound forms a favorable crosslinking reaction with a crosslinking agent (C), and favorable adhesive force and sheet retention are obtained. It is preferable that it is the range of 0.001-20 mass % in (a), and the range of 0.01-5 mass % is more preferable.

When obtaining the said acrylic resin (A), you may use together another vinyl compound other than the said (meth)acrylic compound (a) as needed.

Examples of the above other vinyl compounds include vinyl acetate, vinyl propionate, vinyl laurate, styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, other substituted styrenes, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. can be used. These compounds may be used independently or may use 2 or more types together.

As a manufacturing method of the said acrylic resin (A), the radical polymerization method resulting from the polymerizable double bond which the said (meth)acrylic compound (a) has is mentioned, for example. Specifically, the (meth)acrylic compound (a), if necessary, other vinyl compounds, and a radical polymerization initiator are mixed and stirred at a temperature of preferably 40 to 90° C. to advance radical polymerization. method can be found.

Examples of the polymerization initiator include inorganic peroxides such as hydrogen peroxide, potassium persulfate, sodium persulfate and ammonium persulfate; benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, cumene hydroperoxide, etc. of organic peroxide; 2,2'-azobis-(2-aminodipropane) dihydrochloride, 2,2'-azobis-(N,N'-dimethyleneisobutylamidine) dihydrochloride, 2,2' -Azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, azobisisobutyronitrile, 2,2'-azobis(2-methyl azo compounds such as butyronitrile) can be used. These polymerization initiators may be used independently or may use 2 or more types together.

As the usage-amount in the case of using the said polymerization initiator, it is preferable that favorable polymerizability is acquired and it is the range of 0.001-5 mass % in the prepared raw material of an acrylic resin (A).

As the glass transition temperature of the acrylic resin (A), it is easy to adjust the storage elastic modulus measured under the conditions of a temperature of 20° C. and a frequency of 10 ^-7 Hz of the UV-curable pressure-sensitive adhesive sheet within the range specified in the present invention, -50, It is preferable that it is the range of -30 degreeC, the range of -49-40 degreeC is more preferable, The range of -48--40 degreeC is still more preferable. When the glass transition temperature of the acrylic resin (A) is within this range, good die-cut properties can be obtained while maintaining the flexibility and initial tackiness required at the time of tracking the printing level difference. In addition, the glass transition temperature of the said acrylic resin (A) is each glass transition temperature of the (meth)acrylic compound (a) which is a raw material, and another vinyl compound (it refers to the midpoint glass transition temperature when a homopolymer is formed). , and represents the calculated value calculated by the Fox equation.

The weight average molecular weight of the acrylic resin (A) is preferably in the range of 200,000 to 2 million from the viewpoint of imparting durability in practical use, and imparts smoothness of the sheet to which bubbles are less likely to be mixed during coating at the time of sheet preparation. The range of 200,000-800,000 is more preferable from the point of coating aptitude called , and the range of 200,000-500,000 is still more preferable. In addition, the weight average molecular weight of the said acrylic resin (A) shows the value measured on the following conditions by the gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by TOSOH Co., Ltd.)

Column: The following column by Tosoh Corporation was connected in series and was used.

「TSKgel G5000」(7.8mmI.D.×30cm)×1

「TSKgel G4000」(7.8mmI.D.×30cm)×1

「TSKgel G3000」(7.8mmI.D.×30cm)×1

「TSKgel G2000」(7.8mmI.D.×30cm)×1

Detector: RI (Differential Refractometer)

Column temperature: 40 degrees Celsius

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 mL/min

Injection volume: 100 µL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)

Standard sample: A calibration curve was created using the following standard polystyrene.

(standard polystyrene)

"TSKgel standard polystyrene A-500" manufactured by Toso Corporation

"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation

"TSKgel standard polystyrene A-2500" manufactured by Toso Corporation

"TSKgel standard polystyrene A-5000" manufactured by Toso Corporation

"TSKgel standard polystyrene F-1" manufactured by Toso Corporation

"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation

"TSKgel standard polystyrene F-4" manufactured by Toso Corporation

"TSKgel standard polystyrene F-10" manufactured by Toso Corporation

"TSKgel standard polystyrene F-20" manufactured by Toso Corporation

"TSKgel standard polystyrene F-40" manufactured by Toso Corporation

"TSKgel standard polystyrene F-80" manufactured by Toso Corporation

"TSKgel standard polystyrene F-128" manufactured by Toso Corporation

"TSKgel standard polystyrene F-288" manufactured by Toso Corporation

"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

The crosslinking agent (B) is thermally crosslinked with the hydroxyl group and carboxyl group of the acrylic resin (A) during drying of the organic solvent (D) to be described later to obtain excellent step followability, sheet retention, die cut property and wet heat whitening resistance. It is an essential component for this purpose, and for example, a polyisocyanate crosslinking agent, an epoxy crosslinking agent, a chelate crosslinking agent, a melamine crosslinking agent, etc. can be used. These crosslinking agents may be used independently or may use 2 or more types together.

Examples of the polyisocyanate crosslinking agent include tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenyl. Polyisocyanates, such as methane diisocyanate; These trimethylol propane adducts; These isocyanurate bodies; These biuret bodies, etc. can be used. These crosslinking agents may be used independently or may use 2 or more types together.

As said epoxy crosslinking agent, For example, a bisphenol A epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethyleneglycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether , 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl Ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, etc. can be used. These crosslinking agents may be used independently or may use 2 or more types together.

Examples of the chelate crosslinking agent include acetylacetone coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium; acetoacetic acid ester coordination compounds, etc. Available. These crosslinking agents may be used independently or may use 2 or more types together.

As the melamine crosslinking agent, for example, hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, etc. can be used. . These crosslinking agents may be used independently or may use 2 or more types together.

The amount of the crosslinking agent (B) to be used is preferably in the range of 0.01 to 10 parts by mass based on 100 parts by mass of the acrylic resin (A) from the viewpoint of further improving the balance between step followability and sheet retention, The range of 0.05-5 mass parts is more preferable.

When the (meth)acrylic compound (C) having two or more (meth)acryloyl groups is irradiated with ultraviolet rays, the (meth)acrylic compounds form a crosslinked structure, and Since the cohesive force of the said acrylic resin (A) improves, outstanding moist-heat-resistance whitening property and other durability can be provided. Examples of the (meth)acrylic compound (C) include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, and trimethylolpropane di(meth). Acrylate, hexamethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylic rate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di(trimethylolpropane)di(meth)acrylic rate, di(trimethylolpropane)tri(meth)acrylate, di(trimethylolpropane)tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipenta Aliphatic polyfunctional (meth)acrylates, such as erythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; Tris(2-(meth)acryloyloxyethyl ) polyfunctional (meth)acrylates having an isocyanurate skeleton such as isocyanurate can be used. These (meth)acrylic compounds may be used independently or may use 2 or more types together. Among these, it is preferable to use the (meth)acrylic compound which has 2-6 pieces of (meth)acryloyl groups at the point which originates in polymerizability and can further improve moist-heat whitening resistance and die-cut property, and 3-4 It is more preferable to use the (meth)acrylic compound which has two (meth)acryloyl groups. Moreover, since compatibility with the said acrylic resin (A) and/or a crosslinking agent (B) is improved with high polarity, and further excellent heat-and-moisture whitening resistance is obtained, it is better to use the (meth)acrylic compound which has an oxyalkylene group. It is preferable, and it is preferable to use the (meth)acrylic compound which has an oxyethylene group and/or an oxypropylene group. As an average added mole number of the said oxyalkylene group, it is preferable that it is the range of 1-50 mol in a (meth)acrylic compound from the same reason, and it is more preferable that it is the range of 4-45 mol.

As content of the said (meth)acrylic compound (C), it is the range of 0.5-60 mass parts with respect to 100 mass parts of said acrylic resin (A) from the point which can improve moist-heat resistance whitening property and die-cut property further. It is preferable, and the range of 1-50 mass parts is more preferable.

Examples of the organic solvent (D) include toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, hexane, acetone, cyclohexanone, 3-pentanone, acetonitrile, propionitrile, isobutyronitrile, valerian. Ronitrile, dimethyl sulfoxide, dimethylformamide, etc. can be used. These organic solvents may be used independently or may use 2 or more types together.

As the usage-amount of the said organic solvent (D), it is preferable that it is 80 mass % or less in an adhesive composition from the point which can improve drying property and coatability further, and the range of 5-70 mass % is more preferable.

The said photoinitiator (E) generates radicals by light irradiation, heating, etc., and initiates radical polymerization of the said (meth)acrylic compound (A).

Examples of the photopolymerization initiator (E) include 4-phenoxydichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropyl phenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 4-(2-hydroxyethoxy)-phenyl (2-hydroxy-2-propyl) ketone; Acetophenone compounds such as 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone and 2,2-dimethoxy-2-phenylacetophenone; benzoin, benzoinmethyl ether , benzoin compounds such as benzoin isoethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4 Benzophenone compounds such as '-methyldiphenyl sulfide and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-methylthi thioxanthone compounds such as oxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, isopropyl thioxanthone, and 2,4-diisopropyl thioxanthone; 4,4'- Anthraquinone compounds such as dimethylaminothioxanthone, 4,4'-diethylaminobenzophenone, α-acyloxime ester, benzyl, methylbenzoyl formate, and 2-ethylanthraquinone; 2,4,6-trimethylbenzoyldi Acyl phosphine oxide compounds such as phenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzo A phenone, acrylated benzophenone, etc. can be used. These photoinitiators may be used independently or may use 2 or more types together.

As said photoinitiator (E), since adhesiveness and ultraviolet curability can be improved further, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2 It is preferable to use at least one photopolymerization initiator selected from the group consisting of ,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide is more preferable.

As the usage-amount of the said photoinitiator (E), it is preferable that it is the range of 0.01-5 mass parts in an adhesive composition from the point which can improve ultraviolet curability further, and the range of 0.05-3 mass parts is more preferable.

The adhesive composition used by this invention may contain another additive as needed.

As the above other additives, for example, a silane coupling agent, antioxidant, light stabilizer, rust inhibitor, thixotropy imparting agent, sensitizer, polymerization inhibitor, leveling agent, tackifier, antistatic agent, flame retardant, etc. may be used. can These additives may be used independently or may use 2 or more types together.

As a viscosity of the adhesive composition used by this invention, it is preferable from the point of coatability and workability that it is the range of 500-30,000 mPa*s, and the range of 1,000-20,000 mPa*s is more preferable. In addition, the said viscosity shows the value measured with the B-type viscometer at 25 degreeC.

Next, the manufacturing method of the ultraviolet curing adhesive sheet of this invention is demonstrated.

After coating the said adhesive composition on release paper, the said ultraviolet curable adhesive sheet dries an organic solvent (D), and is obtained by aging as needed after that. In the present invention, since the acrylic resin (A) and the crosslinking agent (B) are thermally crosslinked after drying of the organic solvent (D), an ultraviolet curable adhesive sheet having excellent adhesiveness, step followability, die cut properties and sheet retention properties is obtained

As a method of coating the said adhesive composition on release paper, the method of apply|coating using, for example, an applicator, a roll coater, a knife coater, a gravure coater, a slot die coater, a lip coater, etc. is mentioned.

As drying of the said organic solvent (D), the method of performing at the temperature of 60-120 degreeC for 1 minute - 1 hour is mentioned, for example.

After the drying, for the purpose of further accelerating thermal crosslinking of the urethane resin (A) and the polyisocyanate crosslinking agent, and further improving sheet retention, aging for 1 to 7 days at a temperature of 10 to 40° C. may be done

The thickness of the UV-curable pressure-sensitive adhesive sheet is appropriately determined depending on the intended use, but is, for example, in the range of 10 to 500 µm.

As a storage elastic modulus at the time of measuring on the conditions of the temperature of 20 degreeC of said ultraviolet curing adhesive sheet, and the frequency of 1 Hz, it is preferable that it is the range of 5x10 ³ - 5x10 ⁵ Pa. At 5×10 ³ Pa or more, the yield increases because there is no dimensional error due to sheet retention during transport or storage due to the pressure-sensitive adhesive sticking out of the release film, or sheet deformation during pasting with the panel. Moreover, since there exists moderate adhesive force by setting it as 5x10 ³ Pa or less, the shift|offset|difference in a release film can be suppressed. Moreover, since sheet holding property is further improved, the range of 1×10 ⁴ Pa to 5×10 ⁵ Pa is preferable, and since suitable adhesion to an adherend can be ensured, 5×10 ⁴ to 5×10 ⁵ Pa The range of is more preferable. In addition, the measuring method of the said storage elastic modulus of the said ultraviolet curable adhesive sheet is described in an Example.

The storage elastic modulus of the UV-curable pressure-sensitive adhesive sheet measured at a temperature of 20° C. and a frequency of 10 ^-6 Hz is in the range of 1×10 ³ to 5×10 ⁴ Pa, which prevents the printing step or deformation of the adherend. It is preferable because it is possible to provide flexibility capable of relieving stress at the time of following the adherend and to provide adequate cohesive force to prevent the intrusion of air bubbles from after laminating the adherend, thereby further improving the followability of the step, 2×10 ³ to 5 The range of x10 ⁴ Pa is more preferable. In addition, the measuring method of the said storage elastic modulus of the said ultraviolet curable adhesive sheet is described in an Example.

In addition, as the tensile strength at the time of elongation of 60% in the tensile test measured under the conditions of the temperature of 25 degreeC of the said ultraviolet curable adhesive sheet, and the conditions of a tensile rate of 300 mm/min, since the initial elastic modulus is low, the adhesive deformation amount in low load When this becomes large, it is preferable that it is 7N or less, and it is more preferable that it is the range of 2-7N from the point which print level difference followable|trackability improves further.

Next, the manufacturing method of the adhesive sheet of this invention is demonstrated.

The said adhesive sheet is obtained by ultraviolet-curing the said ultraviolet curable adhesive sheet. The ultraviolet irradiation is, for example, a method of irradiating the ultraviolet curable pressure-sensitive adhesive sheet with a release paper in a state of having the release paper; Method of doing; The method of sticking the ultraviolet curable adhesive sheet which peeled the release paper to one to-be-adhered body, then irradiating an ultraviolet-ray, and sticking another to-be-adhered body after that, etc. are mentioned.

Examples of the adherend include a plastic substrate, a flexible print substrate, a glass substrate, a substrate subjected to a release treatment on these substrates, a substrate on which ITO (indium tin oxide) is vapor-deposited, a touch panel, a liquid crystal module, a cover glass, a cover glass - A touch panel integrated panel (OGS), etc. can be used. In addition, the same to-be-adhered body may be used for both surfaces of an ultraviolet curable adhesive sheet, respectively, or you may use different to-be-adhered bodies.

Examples of the plastic substrate include acrylic resin, PC (polycarbonate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), modified PPE (polyphenylene ether), PET (polyethylene terephthalate) ), COP (cycloolefin polymer), TAC (triacetyl cellulose), etc. as a raw material, a plastic film obtained, an antireflection film, an antifouling film, a film of a transparent conductive film constituting a touch panel, etc. can be used.

In addition, the adherend may have a step difference due to a black printed layer or the like at the end thereof, but since the UV-curable pressure-sensitive adhesive sheet of the present invention has excellent step followability, it can be pasted without leaving a gap in this step portion of the adherend. . Moreover, it is excellent in the level|step difference followability|trackability of this invention, and with respect to the thickness of an adhesive layer, it is 1/1.5 - 1/3, More preferably, it is effective also about a level difference of 1/2 - 1/3. Conventionally, since the followability|trackability with respect to the thickness of about 1/5 - 1/10 with respect to the thickness of an adhesive layer has been discussed, this effect is very excellent.

As a structure when the adhesive sheet of this invention is used for manufacture of an IT-related product, For example, liquid crystal module/adhesive sheet/touch panel, liquid crystal module/adhesive sheet/touch panel/adhesive sheet/cover glass, liquid crystal module /Adhesive sheet/OGS etc. are mentioned.

As a method of irradiating the said ultraviolet-ray, the method of using well-known ultraviolet-ray irradiation apparatuses, such as a xenon lamp, a xenon-mercury lamp, a metal halide lamp, a high pressure mercury lamp, a low pressure mercury lamp, is mentioned, for example.

The irradiation amount of the ultraviolet rays is preferably in the range of 0.05 to 5J/cm ² , more preferably 0.1 to 3J/cm ² , and particularly preferably 0.3 to 1.5 J/cm ² . In addition, the irradiation amount of an ultraviolet-ray is based on the value measured in the wavelength range of 300-390 nm using UVchecker "UVR-N1" by GS Yuasa Corporation.

After the said ultraviolet irradiation, since the said (meth)acrylic compound (C) hardens|cures completely and a crosslinking density improves, the outstanding die-cut property and moist-and-heat resistance whitening are expressed.

The storage elastic modulus when measured under the conditions of a temperature of 20°C and a frequency of 1 Hz of the pressure-sensitive adhesive sheet is in the range of 1×10 ⁴ to 1×10 ⁶ Pa. It is preferable because it can provide high cohesive force at a level that does not cause foaming of the adhesive layer, cloudiness, lowering of adhesive strength, and misalignment of the laminate even during use, and further improving durability such as moisture and heat whitening resistance, preferably 5 × 10 The range of ⁴ to 1×10 ⁶ Pa is more preferable, and the range of 1×10 ⁵ to 6×10 ⁵ Pa is particularly preferable. In addition, the measuring method of the said storage elastic modulus of the said adhesive sheet is described in an Example.

The storage elastic modulus when measured under the conditions of a temperature of 20° C. and a frequency of 10 ^-7 Hz of the pressure-sensitive adhesive sheet is in the range of 1×10 ⁴ to 1×10 ⁶ Pa, high temperature, high temperature, high humidity, and cooling cycle during actual use By providing high cohesive force that does not cause foaming of the adhesive layer, cloudiness, or misalignment of the laminate even under a high load environment, such as under a high load environment, it is preferable because durability such as moisture and heat whitening resistance is further improved, and 1×10 ⁴ The range of ˜5×10 ⁵ Pa is more preferable, and the range of 1×10 ⁴ ˜1×10 ⁵ Pa is particularly preferable. In addition, the measuring method of the said storage elastic modulus of the said adhesive sheet is described in an Example.

As the breaking strength in the tensile test measured under the conditions of a temperature of 25° C. and a tensile rate of 300 mm/min of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive strength becomes stronger, so that lifting or peeling of the pressure-sensitive adhesive at room temperature or under a post-load environment in practical use, foaming It is preferable that it is the range of 100N or more at the point which can suppress these problems further, The range of 110-250N is more preferable, The range of 120-200N is especially preferable. In addition, the measuring method of the said breaking strength of the said adhesive sheet is described in an Example.

The elongation at break in the tensile test measured under the conditions of a temperature of 25° C. and a tensile rate of 300 mm/min of the pressure-sensitive adhesive sheet is a high load when the expansion coefficients of the adherends on both sides are different or the deformation of the adherend is large. It is possible to maintain the shape of the pressure-sensitive adhesive without breaking even during actual use in an environment, and it is difficult to collect water droplets even in a high-temperature, high-humidity environment. It is preferable that it is a range of -1,000%, and the range of 300-900% is more preferable. In addition, the measuring method of the said breaking strength of the said adhesive sheet is described in an Example.

As mentioned above, the ultraviolet curable adhesive sheet of this invention is excellent in step|step difference followability|trackability, sheet|seat holding|maintenance, moist-heat-resistance whitening property, and die-cut property. Therefore, the ultraviolet curable pressure-sensitive adhesive sheet of the present invention can be suitably used as an optical member, and in particular, can be suitably used for manufacturing IT-related products such as touch panels, liquid crystal displays, plasma displays, organic EL, computers, and mobile phones. have.

Example

Hereinafter, the present invention will be described in more detail using examples.

[Synthesis Example 1]

<Synthesis of acrylic resin (A-1)>

73 parts by mass of 2-ethylhexyl acrylate (hereinafter abbreviated as "2EHA"), dicyclopentanyl acrylate ("FA" manufactured by Hitachi Chemical Co., Ltd.) in a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer -513AS") 20 parts by mass, acrylic acid (hereinafter abbreviated as "AA") 5 parts by mass, 2-hydroxyethyl acrylate (hereinafter abbreviated as "HEA") 2 parts by mass, ethyl acetate 50 parts by mass; It heated up to 70 degreeC, putting 50 mass parts of toluene, and blowing nitrogen under stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after holding at 70°C under stirring for 3 hours, the temperature was raised to 75°C, 0.2 parts by mass of tetramethylbutylperoxyethylhexanoate and 1 part by mass of t-hexylperoxypivalate were added and held for 5 hours, The acrylic resin (A-1) of 50 mass % of non-volatile matter, the viscosity 8,540 mPa*s, the weight average molecular weight 440,000, the number average molecular weight 760,000, and glass transition temperature -41.8 degreeC was obtained.

[Synthesis Example 2]

<Synthesis of acrylic resin (A-2)>

73 parts by mass of 2EHA, 20 parts by mass of FA-513AS, 5 parts by mass of AA, 2 parts by mass of HEA, and 100 parts by mass of ethyl acetate in a reaction vessel equipped with a stirrer, reflux cooling pipe, nitrogen inlet pipe, and thermometer. , the temperature was raised to 70°C while blowing nitrogen under stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 50 mass % of non-volatile matter, viscosity 49,900 mPa*s, weight average molecular weight 740,000, number average molecular weight 930,000, free An acrylic resin (A-2) having a transition temperature of -41.8°C was obtained.

[Synthesis Example 3]

<Synthesis of acrylic resin (A-3)>

63 parts by mass of 2EHA, 35 parts by mass of cyclohexyl acrylate (hereinafter abbreviated as "CHA"), 2 parts by mass of 4HBA, and acetic acid in a reaction vessel equipped with a stirrer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer It heated up to 70 degreeC, putting 50 mass parts of ethyl and 50 mass parts of toluene, and blowing in nitrogen under stirring. After 1 hour, 0.04 parts of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 65 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 50 mass % of non-volatile matter, viscosity 8,650 mPa*s, weight average molecular weight 410,000, number average molecular weight 720,000, glass An acrylic resin (A-3) having a transition temperature of -44.4°C was obtained.

[Synthesis Example 4]

<Synthesis of acrylic resin (A-4)>

In a reaction vessel equipped with a stirrer, reflux cooling tube, nitrogen introduction tube and thermometer, 73 parts by mass of 2EHA, 20 parts by mass of isobornyl acrylate (hereinafter abbreviated as "IBXA"), 5 parts by mass of AA, 2 mass parts of HEA, 50 mass parts of ethyl acetate, and 50 mass parts of toluene were put, and it heated up to 70 degreeC, blowing in nitrogen under stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 50.1 mass % of non-volatile matter, viscosity 9,030 mPa*s, weight average molecular weight 440,000, number average molecular weight 74,000, free An acrylic resin (A-4) having a transition temperature of -43.5°C was obtained.

[Synthesis Example 5]

<Synthesis of acrylic resin (A-5)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 55 parts by mass of 2-EHA, 23 parts by mass of n-butyl acrylate (hereinafter abbreviated as "BA"), and 20 parts by mass of IBXA 2 mass parts, 50 mass parts of ethyl acetate, and 50 mass parts of toluene were put for part and 4HBA, and it heated up to 70 degreeC, blowing in nitrogen under stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 50.2 mass % of non-volatile matter, viscosity 9,480 mPa*s, weight average molecular weight 430,000, number average molecular weight 74,000, free An acrylic resin (A-5) having a transition temperature of -45.5°C was obtained.

[Synthesis Example 6]

<Synthesis of acrylic resin (A-6)>

In a reaction vessel equipped with a stirrer, reflux cooling tube, nitrogen inlet tube, and thermometer, 55 mass parts of 2EHA, 28 mass parts of BA, 20 mass parts of methyl methacrylate (hereinafter abbreviated as "MMA"), 4HBA It heated up to 70 degreeC, putting 2 mass parts, 50 mass parts of ethyl acetate, and 50 mass parts of toluene, and blowing in nitrogen while stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, non-volatile matter 51.5 mass %, viscosity 11,790 mPa*s, weight average molecular weight 460,000, number average molecular weight 75,000, glass An acrylic resin (A-6) having a transition temperature of -49°C was obtained.

[Synthesis Example 7]

<Synthesis of acrylic resin (A-7)>

55 mass parts of 2EHA, 20 mass parts of MMA, 2 mass parts of HEA, 50 mass parts of ethyl acetate, and 50 mass parts of toluene were put in a reaction vessel equipped with a stirrer, a reflux cooling tube, nitrogen introduction tube, and a thermometer, and were stirred under stirring. , the temperature was raised to 70°C while blowing nitrogen. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 50.2 mass % of non-volatile matter, viscosity 17,760 mPa*s, weight average molecular weight 370,000, number average molecular weight 67,000, free An acrylic resin (A-7) having a transition temperature of -41.6°C was obtained.

[Synthesis Example 8]

<Synthesis of acrylic resin (A'-1)>

78 parts by mass of 2EHA, 20 parts by mass of BA, 2 parts by mass of 4HBA, and 100 parts by mass of toluene were put in a reaction vessel equipped with a stirrer, reflux cooling pipe, nitrogen inlet pipe, and thermometer, and while nitrogen was blown in 65 It heated up to °C. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after holding at 65°C under stirring for 3 hours, the temperature was raised to 75°C, 0.2 parts by mass of tetramethylbutylperoxyethylhexanoate and 1 part by mass of t-hexylperoxypivalate were added and held for 5 hours, Nonvolatile matter 48.9 mass %, viscosity 4,460 mPa*s, weight average molecular weight 250,000, number average molecular weight 630,000, and the acrylic resin (A'-1) of -56.5 degreeC of glass transition temperature were obtained.

[Synthesis Example 9]

<Synthesis of acrylic resin (A'-2)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 70 parts by mass of 2EHA, 25 parts by mass of vinyl acetate (hereinafter abbreviated as "VAc"), 5 parts by mass of AA, and 50 parts by mass of ethyl acetate Part and 50 mass parts of toluene were put, and it heated up to 70 degreeC, blowing in nitrogen under stirring. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, 51.6 mass % of non-volatile matter, viscosity 47,900 mPa*s, weight average molecular weight 590,000, number average molecular weight 79,000, free An acrylic resin (A'-2) having a transition temperature of -50.1°C was obtained.

[Synthesis Example 10]

<Synthesis of acrylic resin (A'-3)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 75 parts by mass of 2EHA, 20 parts by mass of VAc, 5 parts by mass of AA, 50 parts by mass of ethyl acetate, and 50 parts of toluene were put, and under stirring, It heated up to 70 degreeC, blowing in nitrogen. After 1 hour, 0.04 parts by mass of an azobisisobutyronitrile solution previously dissolved in ethyl acetate was added. Then, after hold|holding at 70 degreeC under stirring for 3 hours, it heated up to 75 degreeC, hold|maintained for 5 hours, non-volatile matter 51.5 mass %, viscosity 14,550 mPa*s, weight average molecular weight 470,000, number average molecular weight 96,000, free An acrylic resin (A'-3) having a transition temperature of -46.1°C was obtained.

[Example 1]

100 parts by mass of the acrylic resin (A-1) obtained in Synthesis Example 1, propoxylated pentaerythritol tetraacrylate (average added moles of oxypropylene groups; 6 mol, or less) in a container equipped with a stirrer, a reflux cooling tube, and a thermometer , "propoxylated PETA") 20 mass parts and 1-hydroxycyclohexyl-phenyl- ketone ("Irgacure184" by BASF) 1 mass part were added, and it stirred until it became uniform. Then, it filtered with a 200 mesh wire mesh, 0.1 mass part of epoxy crosslinking agents (The Mitsubishi Gas Chemical Co., Ltd. make "TETERAD-X", hereafter abbreviate|abbreviated as "EPO-1") was added, and the adhesive composition was obtained.

[Method for Producing Ultraviolet Curable Adhesive Sheet]

The pressure-sensitive adhesive composition is coated on the surface of a release polyethylene terephthalate film having a thickness of 50 µm (hereinafter, abbreviated as "Release PET50") so that the film thickness after drying with an organic solvent becomes 100 µm, dried in a dryer at 80 ° C. for 3 minutes, and UV-curable An adhesive sheet was obtained.

[Method for Measuring Storage Elastic Modulus of Ultraviolet Curable Adhesive Sheet]

The said ultraviolet curable adhesive sheet was laminated|stacked until it became 1 mm in thickness under light-shielding, and the storage elastic modulus was measured on the following conditions using the dynamic viscoelasticity measuring apparatus "MCR-302" manufactured by Anton Parsa.

Measurement temperature; 20-150 degrees Celsius

Parallel plate; 25mmΦ

Angular frequency; ω=500~0.005rad/sec

Deformation amount; 3%

From the obtained frequency dispersion results for each temperature, the frequency f is calculated from f(Hz) = ω/2π, and most of 10 ^-9 to 10 ¹ Hz at 20°C creates a master curve of water dispersion, and the storage elastic modulus is calculated extracted.

[Examples 2-7, Comparative Examples 1-4]

Example 1 except that the types and/or amounts of the acrylic resin (A), crosslinking agent (B), (meth)acrylic compound (C), and photoinitiator (E) used were changed as described in Tables 1 to 3 Similarly, the adhesive composition and the ultraviolet curing adhesive sheet were obtained, and the storage elastic modulus of the ultraviolet curing adhesive sheet was measured.

[Evaluation method of step followability]

One side of the UV curable pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples was overlaid on a polyethylene terephthalate film (PET100) having a thickness of 100 μm, to obtain an UV curable pressure sensitive adhesive sheet with PET100 pasted on one side. What cut this to 50 mm in length and 40 mm in width was used as the test piece. Next, a frame having a length of 40 mm, a width of 30 mm, and a width of 5 mm was cut out from a 50 µm-thick polyethylene terephthalate film. This 50-micrometer-thick edge was put on a glass plate, and the said test piece was pasted from it by 2 kg roll x 2 reciprocation, and it was pasted so that a 50-micrometer edge was pinched|interposed with PET100 and a test piece. This was autoclaved for 20 minutes by the pressure of 0.5 MPa in 50 degreeC atmosphere. Then, it UV-irradiated so that the accumulated light amount of the wavelength of the UV-A area|region after glass permeation|transmission from the glass plate side might be set to 1 J/cm< ² >, and the test piece was obtained. The obtained test piece was left to stand in 80 degreeC atmosphere for 24 hours, the inside of a 50-micrometer-thick edge was visually observed, and the followability with respect to 50 micrometers thickness was evaluated as follows.

"○"; No floating|lifting from a level|step difference, and no mixing|blending of air bubbles.

"Δ"; There is no floatation from the step, and there is some mixing of air bubbles.

"X"; There is mixing of air bubbles.

[Method for evaluating sheet retention properties]

UV-curable pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a square of 20 mm side, the release films on both sides were peeled off, and pasted on a release PET50 of a square of 50 mm side, and sandwiched with a 2 mm thick glass plate, and then placed under a 40 ° C environment. A load of 1 kg/cm ² was applied and left to stand for 24 hours. The sheet area was measured immediately after the load was removed, and the strain of the sheet was calculated by the following formula (1), and evaluated as follows.

Strain rate (%) of sheet = [area of ultraviolet curing adhesive sheet after heating and pressurization (mm ² )-400 (mm ² )]/400 (mm ² )

"○"; 0%, "△"; More than 0% and less than 3%, "X"; 3% or more

[moisture-resistant whitening resistance]

The UV curable adhesive sheet obtained in Examples and Comparative Examples was cut to a width of 50 mm and a length of 40 mm, and through this UV curable adhesive sheet, a float glass having a thickness of 1 mm, a width of 76 mm, and a length of 52 mm, a thickness of 0.6 mm, a width of 80 mm, A polycarbonate plate with a hard coat of 50 mm in length was laminated to prepare a laminate, and it was used as a test piece. The haze and the light transmittance were measured for this according to JISK73611-1-1997 using the turbidimeter "NDH5000" by Nippon Denshoku Industries Co., Ltd. The yellowing degree (b*) was measured using the Konica Minolta Sensing Co., Ltd. spectrophotometer "CM-5000d", according to JISK7105-1981, under the conditions of the light source C and the field of view of 2 degrees. Further, the specimen was left to stand for 500 hours in an atmosphere at a temperature of 85°C and a humidity of 85%, and then taken out in an atmosphere at a temperature of 23°C and a humidity of 50%. After taking out and leaving it to stand at room temperature for 12 hours, the presence or absence of generation|occurrence|production of a bubble was observed visually, haze, light transmittance, and yellowing degree were measured similarly to the method mentioned above, and it evaluated as follows.

"○"; There is no generation|occurrence|production of a bubble, there is neither haze nor an increase in yellowing degree, nor is there a fall in light transmittance.

"Δ"; There was no bubble generation, but a very slight increase in haze and yellowing was confirmed, and a change in light transmittance within ±0.2 was also confirmed.

"x"; generation of bubbles was confirmed, or haze and a rise in the degree of yellowing were observed, and a change in light transmittance exceeding ±0.2 was confirmed.

[Evaluation method of die-cut property]

The UV-curable adhesive sheet obtained in Examples and Comparative Examples was cut to a size of 300 mm in length and 110 mm in width, and 20 half-cuts at intervals of 5 mm in length of 100 mm and 10 mm in width with a die-cut blade in the longitudinal direction, with respect to the blade The presence or absence of adhesion of the adhesive layer was confirmed visually. Then, the release PET side is fixed, and the UV-curable adhesive sheet in the peripheral part is peeled at a speed of 1,000 mm/min by 90°, and the presence or absence of peeling of the blanked part and the presence or absence of the sticking layer are visually checked, , evaluated as follows.

"○"; There is no adhesion of the adhesive layer to the blade, peeling of the blanked portion, and protrusion.

"Δ"; Adherence of the adhesive layer to the blade, peeling off and protrusion of the blanked portion are observed very slightly.

"X"; adhesion of the adhesive layer to a blade, peeling of the blanked part, and protrusion are confirmed clearly.

[Method for Measuring Tensile Strength of Ultraviolet Curable Adhesive Sheet]

The UV-curable adhesive sheets obtained in Examples and Comparative Examples were stacked under light to a thickness of 500 µm, and a test piece having a width of 10 mm and a mark spacing of 20 mm was heated using a Tensilon tensile strength tester "RTF-1210" manufactured by A & D. It was pulled in the longitudinal direction under the conditions of 25 degreeC and the tensile rate of 300 mm/min, and the tensile strength (N) in elongation 60% was measured.

[Method for measuring storage modulus of adhesive sheet]

The ultraviolet curing adhesive sheet obtained by the Example and the comparative example was UV-irradiated so that the accumulated light amount of the wavelength of a UV-A region might be set to 1 J/cm< ² >, and the ultraviolet-cured adhesive sheet was obtained. The obtained adhesive sheet was laminated|stacked until it became 500 micrometers in thickness, and the storage elastic modulus was measured on the following conditions using the dynamic viscoelasticity measuring apparatus "MCR-302" by Anton Parsa.

Measurement temperature; 20-150 degrees Celsius,

Parallel plate; 25mmΦ

Angular frequency：ω=500~0.005rad/sec

Deformation amount; 3%

From the obtained frequency dispersion results for each temperature, the frequency f is calculated from f(Hz) = ω/2π, and most of 10 ^-9 to 10 ¹ Hz at 20°C creates a master curve of water dispersion, and the storage elastic modulus is calculated extracted.

[Method for Measuring Breaking Strength and Breaking Elongation of the Adhesive Sheet]

The UV-curable adhesive sheet obtained in the Example and the comparative example was UV-irradiated so that the accumulated light amount of the wavelength of a UV-A area|region might be set to 1 J/cm< ² >, and the UV-cured adhesive sheet was obtained. The obtained pressure-sensitive adhesive sheet is stacked until it becomes 500 µm in thickness, and using a Tensilon tensile strength tester "RTF-1210" manufactured by A&D Corporation, a test piece having a width of 10 mm and a mark spacing of 20 mm is subjected to a temperature of 25° C. and a tensile rate of 300 mm/min. was pulled in the longitudinal direction, and the breaking strength (N) and the breaking elongation (%) were measured.

[Table 1]

[Table 2]

[Table 3]

The abbreviation in Tables 1-3 is demonstrated.

"XDI adduct body"; Adduct body of xylylene diisocyanate

"MOI"; 2-isocyanate ethyl methacrylate (Showa Denko Co., Ltd. product "Currents MOI")

"EsacureTZT"; a mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (photoinitiator "EsacureTZT" manufactured by Lamberti)

It turned out that Examples 1-7 which are the ultraviolet curing adhesive sheets of this invention are excellent in step|step difference followability|trackability, sheet|seat holding|maintenance, moist-heat-resistance whitening property, and die-cut property.

On the other hand, in Comparative Examples 1 to 4, the storage elastic modulus measured under the conditions of a temperature of 20 ° C. and a frequency of 10 ^-7 Hz of the ultraviolet curing adhesive sheet is less than the range prescribed by the present invention, but the step followability, sheet retention, resistance The wet heat whitening property and the whole die-cut property could not be satisfied.

Claims (6)

An acrylic resin (A) having a hydroxyl group and/or a carboxyl group, a crosslinking agent (B), a (meth)acrylic compound (C) having two or more (meth)acryloyl groups, an organic solvent (D), and a photoinitiator (E) ) is coated on release paper, and the organic solvent (D) is dried to obtain an ultraviolet curable adhesive sheet, wherein the storage elastic modulus measured under the conditions of a temperature of 20 ° C. and a frequency of 10 ^-7 Hz of the ultraviolet curable adhesive sheet is , exceeding 5×10 ³ Pa and less than or equal to 1×10 ⁵ Pa, wherein the (meth)acrylic compound (C) has 3 to 6 (meth)acryloyl groups, at least one of an oxyethylene group and an oxypropylene group It has, and the said crosslinking agent (B) is an epoxy crosslinking agent, The ultraviolet curable adhesive sheet characterized by the above-mentioned. The method according to claim 1,
The glass transition temperature of the acrylic resin (A) is in the range of -50 to -30 ° C., an ultraviolet curable pressure-sensitive adhesive sheet. The method according to claim 1,
The storage modulus measured at a temperature of 20°C and a frequency of 1 Hz is in the range of 5×10 ³ to 5×10 ⁵ Pa,
A storage elastic modulus measured at a temperature of 20°C and a frequency of 10 ^-6 Hz is in the range of 1×10 ³ to 5×10 ⁴ Pa, an ultraviolet curable pressure-sensitive adhesive sheet. The method according to claim 1,
In the tensile test measured under the conditions of a temperature of 25 degreeC and the conditions of a tensile rate of 300 mm/min, the tensile strength in 60% of elongation is 7 N or less, The ultraviolet curable adhesive sheet. It is obtained by ultraviolet-curing the ultraviolet curable adhesive sheet in any one of Claims 1-4, The adhesive sheet characterized by the above-mentioned. 6. The method of claim 5,
The storage modulus measured at a temperature of 20°C and a frequency of 1 Hz is in the range of 1×10 ⁴ to 1×10 ⁶ Pa,
The pressure-sensitive adhesive sheet having a storage elastic modulus measured at a temperature of 20°C and a frequency of 10 ^-7 Hz in the range of 1×10 ⁴ to 1×10 ⁶ Pa.