JP2016108486A - Ultraviolet-curable adhesive composition, ultraviolet-curable adhesive sheet, and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet-curable adhesive composition that can give an ultraviolet-curable adhesive sheet excellent in step followability and shape retention and can impart excellent moisture/heat whitening resistance to a cured product layer produced by irradiating the ultraviolet-curable adhesive sheet with ultraviolet rays.SOLUTION: The ultraviolet-curable adhesive composition comprises (a1) a polyol, (A) an urethane (meth)acrylate, (B) a polyisocyanate crosslinking agent, (C) a (meth)acrylic compound having two or more (meth)acryloyl groups, (D) an organic solvent and (E) a photopolymerization initiator. The ultraviolet-curable adhesive sheet is produced by applying the ultraviolet-curable adhesive composition to a base material and then drying the organic solvent (D).SELECTED DRAWING: None

Description

  The present invention relates to an ultraviolet curable pressure-sensitive adhesive composition that can be suitably used for production of IT-related products.

  A touch panel is installed in a mobile terminal such as a smartphone or a tablet. The touch panel includes a cover glass, an electrode glass / film, and a laminate of a liquid crystal panel. These are adhesive sheets (Optical Clear Adhesive, (Hereinafter abbreviated as “OCA”). In a smartphone, a decorative layer is provided on a cover glass, and a step of about 20 μm is formed. Therefore, the OCA needs to adhere to the cover glass while following the step.

  In recent years, the design of smartphones has increased, and the decorative layer has become thicker, approximately 60 μm. Further, since the tablet has a large screen, the distortion is large, and the OCA is required to have a performance capable of following a thick step or distortion. In particular, from the viewpoint of design, it is necessary to follow a large step without increasing the thickness of the OCA.

  Examples of the UV curable pressure-sensitive adhesive composition that can be used for the OCA include a pressure-sensitive adhesive obtained by using a solventless pressure-sensitive adhesive composition containing urethane acrylate, an acrylic monomer, and a photopolymerization initiator. (For example, see Patent Document 1).

  However, in the method of reducing the crosslinking density of the resin and imparting flexibility like the pressure-sensitive adhesive, the step following property is good, but the pressure-sensitive adhesive is excessively soft, so that it flows at the time of temperature increase during production. As a result, the pressure-sensitive adhesive sticks out and the film thickness becomes non-uniform. Thus, it has been difficult to achieve both the contradictory performance between the step following property and the shape retaining property.

JP 2006-104296 A

  The problem to be solved by the present invention is to obtain an ultraviolet curable pressure-sensitive adhesive sheet excellent in step followability and shape retention, and excellent in a cured product layer obtained by irradiating the ultraviolet curable pressure-sensitive adhesive sheet with ultraviolet rays. Another object of the present invention is to provide an ultraviolet curable pressure-sensitive adhesive composition capable of imparting heat and heat resistance to whitening.

  The present invention relates to polyol (a1), urethane (meth) acrylate (A), polyisocyanate crosslinking agent (B), (meth) acrylic compound (C) having two or more (meth) acryloyl groups, organic solvent (D ) And a photopolymerization initiator (E). An ultraviolet curable pressure-sensitive adhesive composition is provided.

  In addition, the present invention provides an ultraviolet curable pressure-sensitive adhesive sheet obtained by drying the organic solvent (D) after coating the ultraviolet curable pressure-sensitive adhesive composition on a substrate. .

  Furthermore, the present invention provides a laminate characterized in that it is obtained by bonding at least two adherends with the ultraviolet curable pressure-sensitive adhesive sheet and then irradiating with ultraviolet rays.

  The ultraviolet curable pressure-sensitive adhesive composition of the present invention can be used in combination with thermal crosslinking and ultraviolet curing, and is excellent in step followability, shape retention, and cutting properties (there is no adhesive residue on the blade during cutting). A curable adhesive sheet is obtained. Moreover, the hardened | cured material layer obtained by irradiating the said ultraviolet curing adhesive sheet with an ultraviolet-ray is excellent in moisture-heat whitening resistance and durability.

  Therefore, the ultraviolet curable pressure-sensitive adhesive composition of the present invention can be suitably used as an ultraviolet curable pressure-sensitive adhesive composition used for an optical member, and in particular, a touch panel, a liquid crystal display, a plasma display, an organic EL, a personal computer. It can be suitably used for manufacturing IT-related products such as mobile phones.

  The ultraviolet curable pressure-sensitive adhesive composition of the present invention includes a polyol (a1), a urethane (meth) acrylate (A), a polyisocyanate crosslinking agent (B), and a (meth) acrylic compound having two or more (meth) acryloyl groups. (C), an organic solvent (D), and a photoinitiator (E) are contained.

  The polyol (a1) is an essential component for thermally cross-linking with the polyisocyanate cross-linking agent (B) described later to obtain excellent shape retention, and examples thereof include a chain extender having a hydroxyl group, a polyether polyol, and a polycarbonate polyol. Polyester polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, polyacryl polyol, dimer diol, polyisoprene polyol, and the like can be used. These polyols may be used alone or in combination of two or more. Among these, 1 consisting of a chain extender having a hydroxyl group, a polyether polyol, and a polycarbonate polyol from the viewpoint of further improving wet heat and whitening resistance, flexibility, mechanical strength, and shape retention by thermal crosslinking. It is preferable to contain seeds or more.

  Examples of the chain extender having a hydroxyl group include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2 -Butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5- Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1 , 3-propanediol, neopentyl glycol, 2-butyl Aliphatic polyols such as lu-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol Alicyclic polyols such as 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanedimethanol, cycloheptanediol, cyclooctanediol, hydroxypropylcyclohexanol; bisphenol A, bisphenol F, 4 Aromatic polyols such as 4,4'-biphenol can be used. These compounds may be used alone or in combination of two or more. Among these, 1,4-butanediol, 1,5-pentanediol, 1,6-butanediol can be further improved in heat-and-whitening resistance, flexibility, mechanical strength, and shape retention by thermal crosslinking. It is more preferable to use one or more compounds selected from the group consisting of hexanediol, 2-butyl-2-ethyl-1,3-propanediol, and 1,4-cyclohexanedimethanol.

  Examples of the polyether polyol include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxyethylene polyoxytetramethylene polyol, polyoxypropylene polyoxytetramethylene polyol. Etc. can be used. These polyether polyols may be used alone or in combination of two or more. Among these, the group consisting of polyoxyethylene polyol, polyoxypropylene polyol, and polyoxytetramethylene polyol from the viewpoint of further improving the wet heat whitening resistance, flexibility, mechanical strength, and shape retention by thermal crosslinking. It is preferable to use one or more selected polyether polyols.

  As said polycarbonate polyol, what is obtained by making carbonate ester and / or phosgene react with the compound which has a 2 or more hydroxyl group can be used, for example.

  As the carbonate ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used. These carbonates may be used alone or in combination of two or more.

  As the compound having two or more hydroxyl groups, for example, the same compounds as the chain extender having the hydroxyl group can be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use an aliphatic polyol and / or an alicyclic polyol from the point that the cutting property can be further improved. 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol It is more preferable to use one or more compounds selected from the group consisting of 1,4-cyclohexanedimethanol.

  As the amount of the polyol (a1) used, it is possible to further improve the wet heat and whitening resistance, flexibility, and mechanical strength, and further improve the balance between the step following property and the shape retaining property. It is preferably in the range of 0.5 to 30 parts by mass and more preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the urethane (meth) acrylate (A).

  As the number average molecular weight of the polyol (a1), it is possible to further improve the heat and whitening resistance, flexibility, and mechanical strength, and further improve the balance between the step following ability and the shape retention. In the case of using a chain extender having a hydroxyl group as the polyol (a1), the range is preferably from 100 to 450, and when a polyol extender other than a chain extender having a hydroxyl group is used as the polyol (a1). Is preferably in the range of 500 to 7,000, more preferably in the range of 700 to 4,000, and still more preferably in the range of 800 to 3,000. In addition, the number average molecular weight of the said polyol (a1) shows the value measured on condition of the following by gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

  Examples of the urethane (meth) acrylate (A) include those obtained by reacting the polyol (a2), the polyisocyanate (a3), and the (meth) acrylic compound (a4) having an isocyanate group or a hydroxyl group. Can be used.

  The said polyol (a2) used for manufacture of the said urethane (meth) acrylate (A) can use the thing similar to the said polyol (a1). These polyols may be used alone or in combination of two or more. Among these, it is preferable to use a polyether polyol and / or a polycarbonate polyol from the viewpoint that the moisture and heat whitening resistance, flexibility, and mechanical strength can be further improved.

  Examples of the polyisocyanate (a3) include aromatic polyisocyanates such as xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4 Aliphatic or alicyclic polyisocyanates such as' -dicyclohexylmethane diisocyanate, diisocyanate methylcyclohexane, and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, it is preferable to use alicyclic polyisocyanate from the point that mechanical strength, adhesive physical properties and transparency can be further improved, and 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate and diisocyanate. It is more preferable to use one or more polyisocyanates selected from the group consisting of methylcyclohexane.

  The (meth) acrylic compound (a4) having an isocyanate group or a hydroxyl group is used for the purpose of introducing a (meth) acryloyl group into the urethane (meth) acrylate (A).

  In the present invention, “(meth) acryl” means acryl and / or methacryl, “(meth) acrylate” means acrylate and / or methacrylate, and “(meth) acryloyl” means acryloyl. And / or methacryloyl.

  Examples of the (meth) acrylic compound having an isocyanate group that can be used as the compound (a4) include 2- (meth) acryloyloxyethyl isocyanate and 2- (2- (meth) acryloyloxyethyloxy) ethyl. Isocyanate, 1,1-bis ((meth) acryloyloxymethyl) ethyl isocyanate and the like can be used. These compounds may be used alone or in combination of two or more. Among these, 2- (meth) acryloyloxyethyl isocyanate is preferably used from the viewpoint of easy availability of raw materials, and 2-acryloyloxyethyl isocyanate is more preferably used from the viewpoint of ultraviolet curing.

  Examples of the (meth) acrylic compound having a hydroxyl group that can be used as the compound (a4) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (Meth) acrylic acid alkyl ester having a hydroxyl group such as 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, hydroxyethylacrylamide; trimethylolpropane di (meth) Polyfunctional (meth) acrylates having hydroxyl groups such as acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate; polyethylene glycol monoacrylate, poly Propylene glycol monoacrylate may be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use an acrylic acid (meth) alkyl ester having a hydroxyl group from the viewpoint of easy availability of raw materials, ultraviolet curable properties and adhesive properties, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are used. It is more preferable.

  As a manufacturing method of urethane (meth) acrylate (A) in the case of using a (meth) acrylic compound having an isocyanate group as the compound (a4), for example, the polyol (a2) and the polyisocyanate (without solvent) are used. A urethane prepolymer having a hydroxyl group is obtained by charging and reacting with a3), and then a method for producing the (meth) acrylic compound (a4) having an isocyanate group by supplying, mixing, and reacting is used. be able to. The reaction is preferably performed, for example, at 20 to 120 ° C. for 30 minutes to 24 hours.

  As a manufacturing method of the said urethane (meth) acrylate (A) in the case of using the (meth) acryl compound which has a hydroxyl group as the said compound (a4), the said polyol (a2) and the said (meth) are carried out under no solvent, for example. A method in which an acrylic compound (a4) is charged into a reaction system and then the polyisocyanate (a3) is supplied, mixed and reacted; the polyol (a2) and the polyisocyanate (without solvent) are prepared. It is possible to obtain a urethane prepolymer having an isocyanate group by reacting with a3), then supplying the (meth) acrylic compound (a4) having a hydroxyl group, mixing, reacting, and the like. it can. In any case, the reaction is preferably performed, for example, at 20 to 120 ° C. for 30 minutes to 24 hours.

  You may manufacture the said urethane (meth) acrylate (A) in presence of the organic solvent (D) mentioned later.

  In the case of using a (meth) acrylic compound having a hydroxyl group as the compound (a4), the reaction between the polyol (a2), the polyisocyanate (a3) and the (meth) acrylic compound (a4) ) And the equivalent amount of the hydroxyl group of the (meth) acrylic compound (a4) and the isocyanate group of the polyisocyanate (a3) [isocyanate group / total amount of hydroxyl group] = 0.75-1 It is preferable to carry out in the range of from the viewpoint of controlling the molecular weight of the urethane (meth) acrylate (A) to be obtained, and more preferably in the range of 0.79 to 0.995. In addition, the reaction may be carried out when the equivalent ratio exceeds 1, but in that case, it is preferable to use an alcohol such as methanol for the purpose of deactivating the isocyanate group of the urethane (meth) acrylate (A). .

  In the case where a (meth) acrylic compound having an isocyanate is used as the compound (a4), the reaction between the polyol (a2), the polyisocyanate (a3) and the (meth) acrylic compound (a4) Equivalent ratio [total amount of isocyanate groups / hydroxyl group] of the hydroxyl group of (a1) and the total of isocyanate groups of polyisocyanate (a3) and (meth) acrylic compound (a4) = 0.75-1 It is preferable to control the molecular weight of the obtained urethane (meth) acrylate (A), and more preferably in the range of 0.79 to 0.995. In addition, the reaction may be carried out when the equivalent ratio exceeds 1, but in that case, it is preferable to use an alcohol such as methanol for the purpose of deactivating the isocyanate group of the urethane (meth) acrylate (A). .

  Moreover, when manufacturing urethane (meth) acrylate (A), you may use a polymerization inhibitor, a urethanization catalyst, etc. as needed.

  Examples of the polymerization inhibitor include 3,5-bistertiary butyl-4-hydroxytoluene, hydroquinone, methyl hydroquinone, hydroquinone monomethyl ether (methoquinone), para tertiary butyl catechol methoxyphenol, and 2,6-ditertiary butyl cresol. Phenothiazine, tetramethylthiuram disulfide, diphenylamine, dinitrobenzene and the like can be used. These polymerization inhibitors may be used alone or in combination of two or more.

  Examples of the urethanization catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine; metal salts such as potassium acetate, zinc stearate, and tin octylate; dibutyltin laurate, zirconium tetraacetylacetonate, and the like. These organometallic compounds can be used. These urethanization catalysts may be used alone or in combination of two or more.

  The urethane (meth) acrylate (A) has a (meth) acryloyl group that promotes radical polymerization by light irradiation or heating. The (meth) acryloyl group equivalent of the urethane (meth) acrylate (A) is 1,000 to 200,000 g / eq. From the point that the adhesive properties and the step following ability can be further improved. It is preferable that it is the range of 3,000-100,000 g / eq. The range of 5,000 to 80,000 g / eq. The range of is more preferable. In addition, the said (meth) acryloyl group equivalent remove | divided the total mass of the raw material of the said urethane (meth) acrylate (A) by the equivalent of the (meth) acryl group which exists in the said urethane (meth) acrylate (A). Indicates the value.

  As a mass ratio of the urethane bond in the said urethane (meth) acrylate (A), it is 4-20 in the whole quantity of urethane (meth) acrylate (A) from the point which can improve cutting property, adhesive physical property, and level | step difference follow-up property further. It is preferably in the range of mass%, more preferably in the range of 5-15 mass%. In addition, the urethane bond amount of the said urethane (meth) acrylate (A) shows the mass ratio of the urethane bond structure which occupies in the said raw material with respect to the total mass of the raw material of the said urethane (meth) acrylate (A).

  The weight average molecular weight of the urethane (meth) acrylate (A) is preferably in the range of 5,000 to 100,000 from the viewpoint of further improving cutting properties, adhesive physical properties and step following properties, The range of 000 to 50,000 is more preferable. In addition, the weight average molecular weight of the said urethane (meth) acrylate (A) shows the value obtained by measuring similarly to the number average molecular weight of the said polyol (a1).

  The polyisocyanate crosslinking agent (B) is an essential component for crosslinking with the hydroxyl group of the polyol (a1) to obtain excellent shape retention, such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, Polyisocyanates such as tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate; these trimethylolpropane adducts; these isocyanurate bodies; these burette bodies and the like can be used. Among these, it is preferable to use a trimethylolpropane adduct of polyisocyanate and / or an isocyanurate of polyisocyanate from the viewpoint that the balance between the step following property and the shape retention can be further improved.

  The polyisocyanate crosslinking agent (B) is used in an amount of 0. 0 to 100 parts by mass of the urethane (meth) acrylate (A) because the balance between the step following ability and the shape retention can be further improved. It is preferable that it is the range of 1-20 mass parts.

  The (meth) acrylic compound (C) having two or more (meth) acryloyl groups is excellent in moisture and heat whitening resistance and cross-linking with the (meth) acryloyl group of the urethane (meth) acrylate (A). It is an essential component for obtaining excellent step following ability, for example, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, Hexamethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decandiol di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, pentaerythrito Di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, di (trimethylolpropane) di (meth) acrylate, di (trimethylolpropane) tri (meth) acrylate, di (trimethylol) Propane) tetra (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) ) Polyfunctional (meth) having an isocyanurate skeleton such as aliphatic polyfunctional (meth) acrylate such as acrylate, tris (2- (meth) acryloyloxyethyl) isocyanurate ) Acrylate or the like can be used. These (meth) acrylic compounds may be used alone or in combination of two or more. Among these, the polyfunctional (meth) having an aliphatic polyfunctional (meth) acrylate and / or an isocyanurate skeleton from the viewpoint of further improving the balance between moisture whitening resistance and step-following property and shape retention. It is preferable to use an acrylate, and trimethylolpropane tri (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, and tris (2- (meth) acryloyloxyethyl) isocyanate It is more preferable to use one or more (meth) acrylic compounds selected from the group consisting of nurate.

  As content of the said (meth) acrylic compound (C), the said urethane (meth) acrylate (A) 100 from the point which can improve the balance of moisture-and-heat whitening resistance, and a level | step difference followability and shape retention property further. It is preferable that it is the range of 1-30 mass parts with respect to a mass part, and the range of 1-10 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, valeronitrile, dimethyl sulfoxide, dimethylformamide. Etc. can be used. These organic solvents may be used alone or in combination of two or more.

  As the usage-amount of the said organic solvent (D), it is preferable that it is 60 mass% or less in an ultraviolet curable adhesive composition from the point which can improve drying property and coating property further, and 5-50 mass%. A range is more preferred.

  The photopolymerization initiator (E) generates radicals by light irradiation, heating, or the like, and initiates radical polymerization of the urethane (meth) acrylate (A).

  Examples of the photopolymerization initiator (E) include 4-phenoxydichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1- (4-isopropylphenyl) -2. -Hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-methyl- [4- (methylthio) Acetophenone compounds such as phenyl] -2-morpholino-1-propanone and 2,2-dimethoxy-2-phenylacetophenone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin isoethyl ether, benzoin isopropyl ether and benzoin isobutyl ether Benzophenone compounds such as benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3′-dimethyl-4-methoxybenzophenone; thioxanthone, 2- Thioxanthone compounds such as chlorothioxanthone, 2,4-dichlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone; 4,4′-dimethylamino Thioxanthone (also known as Minerals ketone), 4,4′-diethylaminobenzophenone, α-acyloxime ester, benzyl, methylbenzoylformate (“ Viacure 55 "), anthraquinone compounds such as 2-ethylanthraquinone; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide 3,3 ′, 4,4′-tetra (tert-butyloperoxycarbonyl) benzophenone, acrylated benzophenone, and the like can be used. These photopolymerization initiators may be used alone or in combination of two or more.

  As the photopolymerization initiator (E), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2 can be further improved in terms of adhesive properties and ultraviolet curability. It is preferable to use one or more photopolymerization initiators selected from the group consisting of, 4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 6-Trimethylbenzoyldiphenylphosphine oxide is more preferred.

  As a usage-amount of the said photoinitiator (E), it is 0.01-20 mass parts with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can improve sclerosis | hardenability further. It is preferable that the range is 0.1 to 15 parts by mass.

  The ultraviolet curable pressure-sensitive adhesive composition of the present invention may contain other additives as necessary.

  Examples of the other additives include a silane coupling agent, an antioxidant, a light stabilizer, a rust inhibitor, a thixotropic agent, a sensitizer, a polymerization inhibitor, a leveling agent, a tackifier, and an antistatic agent. A flame retardant or the like can be used. These additives may be used alone or in combination of two or more. Among these, when the ultraviolet curable pressure-sensitive adhesive composition of the present invention is used for applications requiring high pressure-sensitive adhesive properties after heat and humidity resistance, it is preferable to contain a silane coupling agent. In addition, when the ultraviolet curable pressure-sensitive adhesive composition of the present invention is used for applications requiring high heat and heat yellowing resistance, it preferably contains an antioxidant and a light stabilizer.

  Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Silane coupling agents having an epoxy group such as 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ) Ethylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) propyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) propylmethyldimethoxy Silane Silane coupling agents having an alicyclic epoxy group such as 2- (3,4-epoxycyclohexyl) propyltriethoxysilane and 2- (3,4-epoxycyclohexyl) propylmethyldiethoxysilane; vinyltrichlorosilane, vinyltrimethoxy Silane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane , 3-acryloxypropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, silicone alkoxy oligomer, etc. That. These silane coupling agents may be used alone or in combination of two or more. Among these, it is preferred to use a silane coupling agent having an epoxy group and / or a silane coupling agent having an alicyclic epoxy group from the viewpoint that the adhesive force after heat and humidity resistance can be further improved. 4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane It is more preferable to use one or more silane coupling agents.

  As the usage-amount in the case of using the said silane coupling agent, 0.01-10 mass with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can improve the adhesive force after heat-and-moisture resistance further. Is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.05 to 1 part by mass.

  Examples of the antioxidant include hindered phenol compounds (primary antioxidants) that capture radicals generated by thermal degradation, phosphorus compounds that decompose peroxides generated by thermal degradation, and sulfur compounds (secondary antioxidants). Agent) and the like.

Examples of the hindered phenol compound include triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-). tert-butyl-4-hydroxyphenyl) propionate, octadecyl [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl- 4-hydroxyphenyl) propionate], benzenepropanoic acid-3,5-bis (1,1-dimethylethyl) -4-hydroxy-C ₇ -C ₉ side chain alkyl ester, 4,6-bis (dodecylthiomethyl) -O-cresol, N-phenylbenzenamine and 2,4,4-trimethylpente Product of 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 3,9-bis [2- [3- (t -Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro [5 · 5] undecane, 2,6-di-tert-butyl -4-methylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,5-di-tert-amylhydroquinone, and the like can be used. These compounds may be used alone or in combination of two or more.

  Examples of the phosphorus compound include triphenylphosphine, bis (2,4-di-tert-butyl-6-methylphenyl) = ethyl phosphite, triphenyl phosphite, trisnonylphenyl phosphite, tris (2, 4-dibutylphenyl) phosphite, tris (2,4-dibutyl-5-methylphenyl) phosphite, tris [2-tert-butyl-4- (3-butyl-4-hydroxy-5-methylphenylthio)- 5-methylphenyl] phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, di (tridecyl) pentaerythritol di Phosphite, di (nonylphenyl) pentaerythritol Diphosphite, bis (2,4-dibutylphenyl) pentaerythritol diphosphite, bis (2,6-dibutyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4,6-tributylphenyl) pentaerythritol diphosphite Phosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, tetra (tridecyl) isopropylidene diphenol diphosphite, tetra (tridecyl) -4,4′-n-butylidenebis (2-butyl-5) -Methylphenol) diphosphite, hexa (tridecyl) -1,1,3-tris (2-methyl-4-hydroxy-5-butylphenyl) butane triphosphite, tetrakis (2,4-dibutylphenyl) biphenylene diphosphonite, 9,10-di Idro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2′-methylenebis (4,6-butylphenyl) -2-ethylhexyl phosphite, 2,2′-methylenebis (4,6- Butylphenyl) -octadecylphosphite, 2,2′-ethylidenebis (4,6-dibutylphenyl) fluorophosphite, tris (2-[(2,4,8,10-tetrakisbutyldibenzo [d, f] [ 1,3,2] dioxaphosphin-6-yl) oxy] ethyl) amine, 2-ethyl-2-butylpropylene glycol and 2,4,6-tributylphenol phosphite, and the like can be used. These compounds may be used alone or in combination of two or more.

  Examples of the sulfur compound include didodecyl-3,3′-thiopropionate, dilauryl-3,3′-thiodipropionate, laurylthiothiothionate, ditridecyl-3,3′-thiodipropionate, Dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, tetrakis-methylene-3-laurylthiopropionate methane, distearyl-3,3′-methyl-3, 3′-thiodipropionate, lauryl stearyl-3,3′-thiodipropionate, bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide, β- Lauryl thiopropionate, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimi Tetrazole, can be used dioctadecyl 3,3'-thio dipropionate isethionate, and the like. These compounds may be used alone or in combination of two or more.

  Among these, it is preferable to use a phosphorus compound from the viewpoint of further improving adhesive strength and heat and heat yellowing resistance, and triphenylphosphine, bis (2,4-di-tert-butyl-6-methylphenyl) = ethyl. It is more preferable to use one or more antioxidants selected from the group consisting of phosphite and tris (2,4-di-tert-butylphenyl) phosphite, and triphenylphosphine and bis (2,4-di More preferably, -tert-butyl-6-methylphenyl) = ethyl = phosphite is used.

  As the usage-amount in the case of using the said antioxidant, the range of 0.01-10 mass parts with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can further improve wet heat yellowing resistance. It is preferable that

  The light stabilizer captures radicals generated by photodegradation. For example, a radical scavenger such as a thiol compound, a thioether compound, or a hindered amine compound; an ultraviolet absorber such as a benzophenone compound or a benzoate compound may be used. it can. These light stabilizers may be used alone or in combination of two or more. Among these, it is preferable to use a hindered amine compound from the viewpoint that the heat and heat yellowing resistance can be further improved.

  Examples of the hindered amine compound include a reaction product of cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro 1,3,5-triazine. Product of 2-aminoethanol with decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane A hindered amine compound having an amino ether group such as a reaction product of N; N-acetyl-3-dodecyl-1- (2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione and the like N -Acetyl hindered amine compound; bis (1,2,2,6,6-pentamethyl-4-piperidyl) = decanedioate, bis 1,2,2,6,6, -pentamethyl-4-piperidyl) {[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl} butyl malonate, dimethyl succinate (2-Hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, Provandioic acid [{4-methoxyphenyl} methylene] -bis (1,2,2,6, N-alkyl hindered amine compounds of 6-pentamethyl-4-piperidyl) ester and the like can be used. These compounds may be used alone or in combination of two or more.

  As the usage-amount in the case of using the said light stabilizer, the range of 0.01-10 mass parts with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can improve a heat-and-humidity yellowing resistance further. It is preferable that

  As a viscosity of the ultraviolet curable adhesive composition of this invention, it is preferable that it is the range of 500-30,000 mPa * s from the point of coating property and workability | operativity, and is 1,000-20,000 mPa * s. A range is more preferred. In addition, the said viscosity shows the value measured with the B-type viscometer at 25 degreeC.

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

  The ultraviolet curable pressure-sensitive adhesive sheet is obtained by coating the ultraviolet curable pressure-sensitive adhesive composition on a substrate, drying the organic solvent (D), and then aging as necessary. In the present invention, in the drying step of the organic solvent (D), the urethane resin (A), the polyisocyanate crosslinking agent (B), and the (meth) acrylic compound (C) are thermally crosslinked, so An ultraviolet curable pressure-sensitive adhesive sheet having moldability is obtained.

  Examples of the method of applying the ultraviolet curable pressure-sensitive adhesive composition to a substrate include a method of applying using an applicator, a roll coater, a knife coater, a gravure coater and the like.

  As the base material, for example, a plastic base material, a flexible print base material, a glass base material, a base material obtained by subjecting these base materials to a mold release treatment, a base material obtained by vapor deposition of ITO (indium tin oxide), or the like is used. Can do.

  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), A plastic film obtained by using TAC (triacetylcellulose) or the like as a raw material, an antireflection film, an antifouling film, a transparent conductive film constituting a touch panel, or the like can be used.

  Examples of the drying of the organic solvent (D) include a method in which the temperature is 60 to 120 ° C. for 1 minute to 1 hour.

  After the drying, for the purpose of further promoting the thermal crosslinking of the urethane resin (A), the polyisocyanate crosslinking agent (B) and the (meth) acrylic compound (C), and further improving the shape retention, Aging may be performed at a temperature of 10 to 40 ° C. for 1 to 7 days.

  The thickness of the ultraviolet curable pressure-sensitive adhesive sheet is appropriately determined according to the intended use, and is, for example, in the range of 10 to 500 μm.

  Next, the manufacturing method of the laminated body of this invention is demonstrated.

  The laminate is obtained by bonding at least two adherends with the ultraviolet curable pressure-sensitive adhesive sheet and then irradiating with ultraviolet rays. In addition,

  As the adherend, in addition to the above-described base material, in particular, when the laminate of the present invention is used for manufacturing IT-related products, for example, a touch panel, a liquid crystal module, a cover glass, a cover glass-touch panel A body panel (OGS) or the like can be used.

  In addition, although the said adherend may have a level | step difference by a black printed layer etc. at the edge part, since the ultraviolet curable adhesive sheet of this invention has the outstanding level | step difference followability, it is in this level | step difference part of the said adherend. It can be pasted without leaving a gap.

  As a structure in case the laminated body of this invention is used for manufacture of IT related products, for example, liquid crystal module / cured material layer of UV curable pressure sensitive adhesive sheet / touch panel, liquid crystal module / cured material layer of UV curable pressure sensitive adhesive sheet / Touch panel / cured material layer of UV curable adhesive sheet / cover glass, liquid crystal module / cured material layer of UV curable adhesive sheet / OGS, and the like.

Examples of the ultraviolet irradiation method include a method using a known ultraviolet light irradiation device such as a xenon lamp, a xenon-mercury lamp, a metal halide lamp, a high pressure mercury lamp, or a low pressure mercury lamp.

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

  After the ultraviolet irradiation, the urethane (meth) acrylate (A) and the (meth) acrylic compound (C) are completely cured and the crosslink density is improved, so that excellent moisture and heat whitening resistance is exhibited.

  The ultraviolet curable pressure-sensitive adhesive composition of the present invention can be used in combination with thermal crosslinking and ultraviolet curing, and an ultraviolet curable pressure-sensitive adhesive sheet having excellent step following property, shape retaining property, and cutting property can be obtained. Moreover, the hardened | cured material layer obtained by irradiating the said ultraviolet curing adhesive sheet with an ultraviolet-ray is excellent in moisture-heat whitening resistance and durability.

  Therefore, the ultraviolet curable pressure-sensitive adhesive composition of the present invention can be suitably used as an ultraviolet curable pressure-sensitive adhesive composition used for an optical member, and in particular, a touch panel, a liquid crystal display, a plasma display, an organic EL, a personal computer. It can be suitably used for manufacturing IT-related products such as mobile phones.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Synthesis Example 1]
<Synthesis of urethane acrylate (A-1)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 202 parts by weight of polypropylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PPG1000”), 1,4-hexanediene. 41 parts by mass of methanol (hereinafter abbreviated as “CHDM”), 1.3 parts by mass of 2-hydroxyethyl acrylate (hereinafter abbreviated as “HEA”), 2,6-di-tert-butyl-cresol 1.1 parts by mass and 0.18 parts by mass of p-methoxyphenol were added. After raising the temperature in the reaction vessel to 40 ° C., 110 parts by mass of isophorone diisocyanate (hereinafter abbreviated as “IPDI”) was added. Therefore, 0.1 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Then, after hold | maintaining at 80 degreeC for 12 hours and confirming that all the isocyanate groups have lose | disappeared, it cooled and obtained urethane acrylate (A-1). In the obtained urethane acrylate (A-1), the equivalent of acryloyl group is 63,000 (rounded to two significant digits. The molecular weight of 2-hydroxyethyl acrylate is 116.1. The same applies hereinafter), weight average The molecular weight was 29,000.

[Example 1]
<Preparation of UV-curable adhesive composition>
In a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 5 parts by mass of CHDM, 100 parts by mass of the urethane acrylate (A-1), and a nurate of hexamethylene diisocyanate ("Duranate TSS-100" manufactured by Asahi Kasei Chemicals Corporation) ”, Hereinafter abbreviated as“ TSS-100 ”), 17 parts by mass, trimethylolpropane triacrylate (“ Aronix M-309 ”manufactured by Toagosei Co., Ltd., hereinafter abbreviated as“ M-309 ”), 5 parts by mass. Then, 60 parts by mass of ethyl acetate was added and stirred until uniform. Thereafter, the mixture was cooled to room temperature, and 0.54 parts by mass of 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide (hereinafter abbreviated as “(E-1)”) under stirring, bis (2) decanedioic acid (2 , 2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester and 0.5 parts by weight of triphenylphosphine were sequentially added and stirred until uniform. Thereafter, the mixture was filtered through a 200 mesh wire net to obtain an ultraviolet curable pressure-sensitive adhesive composition.

[Example 2]
In a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 5 parts by mass of polyoxytetramethylene polyol (number average molecular weight; 650, hereinafter abbreviated as “PTMG650”), the urethane acrylate (A-1) 100 Part by mass, 3.7 parts by mass of TSS-100, 5 parts by mass of M-309 and 54 parts by mass of ethyl acetate were added and stirred until uniform. Thereafter, the mixture was cooled to room temperature, and 0.5 parts by mass of (E-1), decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester was stirred with stirring. 0.5 parts by mass and 0.5 parts by mass of triphenylphosphine were sequentially added and stirred until uniform. Thereafter, the mixture was filtered through a 200 mesh wire net to obtain an ultraviolet curable pressure-sensitive adhesive composition.

[Comparative Example 1]
An ultraviolet curable pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 5 parts by mass of CHDM and 17 parts by mass of TSS-100 were changed to 0 parts by mass.

[Comparative Example 2]
An ultraviolet curable pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 10 parts by mass of M-309 was changed to 0 parts by mass.

[Production method of UV curable adhesive sheet]
UV curable pressure-sensitive adhesives obtained in Examples and Comparative Examples so that the film thickness after drying the organic solvent is 100 μm on the surface of a 50 μm-thick polyethylene terephthalate film (release PET 50) having a release treatment on the surface. The fat composition was applied and dried in an 80 ° C. dryer for 3 minutes to obtain an ultraviolet curable pressure-sensitive adhesive sheet.

[Evaluation method for resistance to moist heat whitening]
The ultraviolet curable pressure-sensitive adhesive sheet was bonded to a polyethylene terephthalate film (PET100) having a thickness of 100 μm to produce a laminate in which PET100 was bonded. This was cut into 50 mm length and 40 mm width. Then, ultraviolet rays were irradiated from the glass plate side so that the integrated light quantity of the wavelength of the UV-A region after passing through the glass plate was 1 J / cm ² to obtain a laminate having an adhesive sheet, which was used as a test piece. The haze (%) of the test piece was measured with a turbidimeter “NDH5000” (manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 7361-1. Next, the obtained test piece was allowed to stand for 100 hours under the conditions of 85 ° C. and 85% RH (hereinafter abbreviated as “after wet heat resistance test”), and then taken out in an atmosphere of 23 ° C. and 50% RH. . Within 10 minutes after removal, the haze (%) was measured with a turbidimeter “NDH5000” (manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 7361-1, and the moisture and heat whitening resistance was as follows. Evaluated.
“T”: The difference in haze (%) value before and after the wet heat resistance test is less than 1%.
“F”: The difference in haze (%) values before and after the wet heat resistance test is 1% or more.

[Evaluation method of step following ability]
The ultraviolet curable pressure-sensitive adhesive sheet was bonded to a 100 μm-thick polyethylene terephthalate film (PET100), and a laminate in which PET100 was bonded to one side was produced. What cut | judged this to length 50mm and width 40mm was used as the test piece. Separately, a frame having a length of 40 mm, a width of 30 mm, and a width of 5 mm was cut from the PET 50. The frame having a thickness of 50 μm was placed on a glass plate, and the test piece was reciprocated by 2 kg rolls × 2 from the glass plate so that the frame having a thickness of 50 μm was sandwiched between PET 100 and the test piece. This was auto-flavored for 20 minutes at 50 ° C. and 0.5 MPa. Then, the ultraviolet rays were irradiated from the glass plate side so that the integrated light quantity of the wavelength of the UV-A area | region after permeate | transmitting a glass plate might be set to 1 J / cm < ² >, and the laminated body which has an adhesive sheet was obtained. The inner part of the 50-micrometer-thick frame of the obtained laminated body was observed visually, and the followability with respect to a 50-micrometer level | step difference was evaluated as follows.
“T”: There is no floating from the step, and there is no mixing of bubbles.
“F”: There is no lift from the level difference, but even a part of the bubbles is confirmed.

[Method for evaluating shape retention]
The laminate prepared by the above [Method for evaluating resistance to moist and heat whitening] was cut into 25 mm × 25 mm, and a PET film subjected to a release treatment in which both side PET films were cut into 40 mm × 40 mm was used as a test piece. The obtained test piece was sandwiched between glass plates, placed with a 5 kg weight, and allowed to stand in an atmosphere of 40 ° C. for 1 hour. Next, the ratio of the area of the pressure-sensitive adhesive sheet after being left to the area of the pressure-sensitive adhesive sheet before being left (25 mm × 25 mm = 625 mm ² ) was calculated, and the evaluation of the shape retention was evaluated as follows.
“T”: The area magnification of the pressure-sensitive adhesive sheet after being left is less than 103%.
“F”: The area magnification of the pressure-sensitive adhesive sheet after being left is 103% or more.

  It turned out that Example 1 and 2 which are the ultraviolet curable adhesive compositions of this invention are excellent in heat-and-moisture whitening resistance, level | step difference followability, and shape retention property.

  On the other hand, Comparative Example 1 is an embodiment in which the polyol (a1) and the polyisocyanate cross-linking agent (B) are not used. However, although the pressure follows the step by pressure, the ultraviolet curable pressure-sensitive adhesive sheet flows and the shape retention is poor. there were.

  Although the comparative example 2 is an aspect which does not use a (meth) acryl compound (C), moisture-and-heat whitening resistance was unsatisfactory.

Claims (7)

Polyol (a1), urethane (meth) acrylate (A), polyisocyanate crosslinking agent (B), (meth) acrylic compound (C) having two or more (meth) acryloyl groups, organic solvent (D), and An ultraviolet curable pressure-sensitive adhesive composition comprising a photopolymerization initiator (E). The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the polyol (a1) contains one or more of a chain extender having a hydroxyl group, a polyether polyol, and a polycarbonate polyol. The urethane (meth) acrylate (A) is obtained by reacting a polyol (a2), a polyisocyanate (a3), and a (meth) acrylic compound (a4) having an isocyanate group or a hydroxyl group. The ultraviolet curable adhesive composition of description. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the polyisocyanate crosslinking agent (B) is a trimethylolpropane adduct of polyisocyanate and / or an isocyanurate of polyisocyanate. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic compound (C) is an aliphatic polyfunctional (meth) acrylate and / or a polyfunctional (meth) acrylate having an isocyanurate skeleton. An ultraviolet curable pressure-sensitive adhesive sheet obtained by drying the organic solvent (D) after coating the ultraviolet curable pressure-sensitive adhesive composition according to any one of claims 1 to 5 on a substrate. A laminate obtained by bonding at least two adherends with the ultraviolet curable pressure-sensitive adhesive sheet according to claim 6 and then irradiating with ultraviolet rays.