JPWO2016092971A1 - Ultraviolet curable adhesive composition, method for producing ultraviolet curable adhesive sheet, and method for producing laminate - Google Patents

Abstract

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 a urethane resin (A) having a hydroxyl group and a (meth) acryloyl group, a polyisocyanate crosslinking agent (B), a (meth) acrylic compound (C) having two or more (meth) acryloyl groups, an organic solvent ( The present invention provides an ultraviolet curable pressure-sensitive adhesive composition comprising D) and a photopolymerization initiator (E). Moreover, this invention provides the manufacturing method of the ultraviolet curable adhesive sheet characterized by being obtained by drying the organic solvent (D), after apply | coating the said ultraviolet curable adhesive composition to a base material. Is.

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 the 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 (without involving bubbles or the like). is there.

  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 be capable of following a thicker 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 imparting flexibility by reducing the crosslinking density of the resin as in the above-mentioned pressure-sensitive adhesive, the step followability is good, but if the pressure-sensitive adhesive is too soft, it flows during heating and entrains bubbles. And sticking out of the adhesive and non-uniform film thickness. 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 a urethane resin (A) having a hydroxyl group and a (meth) acryloyl group, a polyisocyanate crosslinking agent (B), a (meth) acrylic compound (C) having two or more (meth) acryloyl groups, an organic solvent ( The present invention provides an ultraviolet curable pressure-sensitive adhesive composition comprising D) and a photopolymerization initiator (E).

  Moreover, this invention provides the manufacturing method of the ultraviolet curable adhesive sheet characterized by being obtained by drying the organic solvent (D), after apply | coating the said ultraviolet curable adhesive composition to a base material. Is.

  Furthermore, the present invention provides a method for producing a laminate, which is obtained by bonding at least two adherends with the ultraviolet curable 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 an ultraviolet curable pressure-sensitive adhesive sheet excellent in step followability and shape retention can be obtained. Moreover, the hardened | cured material layer obtained by irradiating the said ultraviolet curable adhesive sheet with an ultraviolet-ray is excellent in moisture-and-heat whitening resistance.

  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 urethane resin (A) having a hydroxyl group and a (meth) acryloyl group, a polyisocyanate crosslinking agent (B), and a (meth) acryl having two or more (meth) acryloyl groups. A compound (C), an organic solvent (D), and a photoinitiator (E) are contained.

  The urethane resin (A) has a hydroxyl group and a (meth) acryloyl group, and when the organic solvent (D) is dried, the hydroxyl group is thermally crosslinked with a polyisocyanate crosslinking agent (B) described later, and has excellent shape retention. In addition, since it has an appropriate flexibility before UV curing, even if it is bonded to a substrate having a step, it can follow well without entraining bubbles or the like. Furthermore, the (meth) acryloyl group crosslinks with the (meth) acrylic compound (C) described later by ultraviolet irradiation, and the crosslink density is increased, whereby excellent moisture and heat whitening resistance can be exhibited.

  As the urethane resin (A), for example, a polyol (a1), a polyisocyanate (a2), and a (meth) acrylic compound (a3) having a hydroxyl group or an isocyanate group can be reacted under conditions where the hydroxyl group becomes excessive. Can be used.

  Examples of the polyol (a1) include polyether polyol, polycarbonate polyol, polyester polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, polyacryl polyol, dimer diol, polyisoprene polyol, and the like. These polyols may be used alone or in combination of two or more. Among these, it is preferable to contain a polyether polyol and / or a polycarbonate polyol from the viewpoint that moisture and heat whitening resistance that is much superior to that of the skeleton can be obtained.

  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, one or more polyether polyols selected from the group consisting of polyoxyethylene polyols, polyoxypropylene polyols and polyoxytetramethylene polyols are used from the viewpoint of further improving the resistance to moist heat whitening and flexibility. It is preferable.

  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.

  Examples of the compound having two or more hydroxyl groups include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, and 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, neopentylglyce 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol Aliphatic polyols such as 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanedimethanol, cycloheptanediol, cyclooctanediol, hydroxypropylcyclohexanol, etc .; bisphenol A An aromatic polyol such as bisphenol F or 4,4′-biphenol 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 viewpoint that the cutting property (no adhesive residue at the time of cutting) can be further improved, and 1,4-butanediol, 1,5-pentane It is more preferable to use one or more compounds selected from the group consisting of diol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol.

  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. The range is preferably from 500 to 7,000, more preferably from 700 to 4,000, and still more preferably from 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

  As said polyol (a1), you may use together the chain extender of the range of the number average molecular weights 50-400 which has a hydroxyl group as needed.

  As said chain extender, the same thing as the compound which has a 2 or more hydroxyl group used for the raw material of the said polycarbonate polyol can be used, for example. Among these, 1,4-butanediol and 1,5-pentane are preferable because a hard segment having an appropriate chain length can be introduced into the urethane resin (A), and excellent shape retention and moisture and heat whitening resistance can be obtained. It is more preferable to use one or more compounds selected from the group consisting of diol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol.

  When using the said chain extender, it is preferable that it is the range of 3-50 mass% in a polyol (a1), and it is more preferable that it is the range of 5-20 mass%.

  Examples of the polyisocyanate (a2) 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 (a3) having a hydroxyl group or an isocyanate group is used for the purpose of introducing a (meth) acryloyl group into the urethane resin (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 a hydroxyl group that can be used as the compound (a3) 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.

  Examples of the (meth) acrylic compound having an isocyanate group that can be used as the compound (a3) 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.

  As a manufacturing method of the said urethane resin (A) in the case of using the (meth) acrylic compound which has a hydroxyl group as said compound (a3), the said polyol (a1) and the said (meth) acrylic compound ( After preparing a3) in the reaction system, the above-mentioned polyisocyanate (a2) is supplied, mixed, and reacted to produce a method. The reaction is preferably performed, for example, at 20 to 120 ° C. for 30 minutes to 24 hours.

  As a manufacturing method of the urethane resin (A) when using a (meth) acrylic compound having an isocyanate group as the compound (a3), for example, in the absence of a solvent, the polyol (a1), the polyisocyanate (a2), A urethane prepolymer having a hydroxyl group can be obtained by charging and reacting, and then the (meth) acrylic compound (a3) having an isocyanate group is supplied, mixed, and reacted to be used. . The reaction is preferably performed, for example, at 20 to 120 ° C. for 30 minutes to 24 hours.

  The urethane resin (A) may be produced in the presence of an organic solvent (D) described later.

  The reaction of the polyol (a1), the polyisocyanate (a2), and the (meth) acrylic compound (a3) when producing the urethane resin (A) is carried out by reacting the hydroxyl group of the polyol (a1) and the ( Equivalent ratio of the total amount of hydroxyl groups of the (meth) acrylic compound (a3) and the total amount of isocyanate groups of the polyisocyanate (a2) and the isocyanate group of the (meth) acrylic compound (a3) [isocyanate group / hydroxyl group ] = 0.75 to 1 is preferable for controlling the molecular weight of the urethane resin (A) to be obtained, and more preferably 0.79 to 0.995. The reaction may be carried out when the equivalent ratio exceeds 1, but in that case, 1,2-propylene glycol or 1,3-propylene glycol is used for the purpose of deactivating the isocyanate group of the urethane resin (A). It is preferable to use a bifunctional alcohol composed of primary and secondary hydroxyl groups such as butylene glycol. In that case, the total amount of the hydroxyl group of the polyol (a1), the hydroxyl group of the (meth) acrylic compound (a3) and the hydroxyl group of the alcohol, and the equivalent ratio of the polyisocyanate group [isocyanate group / hydroxyl group It is preferable to adjust so that [total amount] is within the above range.

  Moreover, as alcohol which can be used in order to deactivate the isocyanate group of the said urethane resin (A), you may use together monofunctional alcohols, such as methanol, ethanol, a propanol, a butanol, for example.

  When manufacturing a urethane resin (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 content of the hydroxyl group in the urethane resin (A) is from 0.01 to 0.00 because it is possible to obtain good shape retention and step following ability by thermal crosslinking and to maintain the moisture and heat whitening resistance at a high level. The range is preferably 5 mol / kg, more preferably 0.02 to 0.2 mol / kg.

  The content of the (meth) acryloyl group in the urethane resin (A) is 0. from the viewpoint that good heat and heat whitening resistance by ultraviolet curing can be obtained, and the shape retention and step following ability can be maintained at a high level. It is preferably in the range of 005 to 0.5 mol / kg, more preferably in the range of 0.01 to 0.2 mol / kg.

  As a mass ratio of the urethane bond in the urethane resin (A), a range of 4 to 20% by mass in the urethane resin (A) is obtained from the point that good cutting property, adhesive physical property and wet heat and whitening resistance can be obtained by hydrogen bonding. It is preferable that it is in the range of 5 to 15% by mass. In addition, the urethane bond amount of the said urethane resin (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 resin (A).

The weight average molecular weight of the urethane resin (A) is preferably in the range of 5,000 to 200,000, from 15,000 to 100,000, from the viewpoint of adhesive properties, shape retention and step following ability. A range is more preferred. 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 cross-linking agent (B) is an essential component for obtaining an ultraviolet curable pressure-sensitive adhesive sheet that is thermally cross-linked with the hydroxyl group of the urethane resin (A) and has excellent shape retention, such as toluene diisocyanate, Polyisocyanates such as chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate; these trimethylolpropane adducts; these isocyanurate bodies; Can be used. Among these, use of a polyisocyanate trimethylolpropane adduct and / or a polyisocyanate isocyanurate from the standpoint that excellent shape retention due to three-dimensional crosslinking is exhibited and the step following ability can be maintained at a high level. The polyisocyanate is preferably one selected from the group consisting of toluene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate because it has an appropriate chain length. Is more preferable.

  As a usage-amount of the said polyisocyanate crosslinking agent (B), the range of 0.1-10 mass parts with respect to 100 mass parts of said urethane resins (A) from the crosslinkable point with the said urethane resin (A). Preferably, the range of 0.2 to 5 parts by mass is more preferable.

  The (meth) acrylic compound (C) having two or more (meth) acryloyl groups is an essential component for obtaining excellent moisture and heat whitening resistance, such as ethylene glycol di (meth) acrylate and propylene glycol diene. (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-decanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra ( ) Acrylate, di (trimethylolpropane) di (meth) acrylate, di (trimethylolpropane) tri (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, dipentaerythritol di (meth) acrylate, di Aliphatic polyfunctional (meth) acrylates such as pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris (2- ( A polyfunctional (meth) acrylate having an isocyanurate skeleton such as (meth) acryloyloxyethyl) isocyanurate can be used. These (meth) acrylic compounds may be used alone or in combination of two or more. Among these, from the point that good ultraviolet curability can be obtained, moist heat whitening resistance, and since the appropriate hardness can be imparted, the balance between the step following ability and the shape retention can be further improved. It is preferable to use a polyfunctional (meth) acrylate and / or a polyfunctional (meth) acrylate having an isocyanurate skeleton. 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri It is more preferable to use one or more (meth) acrylic compounds selected from the group consisting of (meth) acrylate, pentaerythritol tetra (meth) acrylate, and tris (2- (meth) acryloyloxyethyl) isocyanurate.

  The amount of the (meth) acrylic compound (C) used is 100 parts by mass of the urethane resin (A) from the viewpoint of further improving the balance between moisture and heat whitening resistance, and step balance and shape retention. On the other hand, it is preferable that it is the range of 1-50 mass parts, and the range of 3-40 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 80 mass% or less in an ultraviolet curable adhesive composition from the point which can improve drying property and coating property further, 5-70 mass%. A range is more preferred.

  The photopolymerization initiator (E) generates radicals by light irradiation, heating, or the like, and initiates radical polymerization between the (meth) acrylic compounds (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 the usage-amount of the said photoinitiator (E), it is 0.01-10 mass parts with respect to 100 mass parts of said (meth) acrylic compounds (C) from the point which can improve sclerosis | hardenability further. Preferably, the range is 0.05 to 5 parts by mass, and more preferably 0.05 to 1 part 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.

  The amount used in the case of using the antioxidant is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the urethane resin (A), from the point that moisture heat yellowing resistance can be further improved. Is preferred.

  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.

  The amount used in the case of using the light stabilizer is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the urethane resin (A), from the point that moisture heat yellowing resistance can be further improved. Is preferred.

  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, after the organic solvent (D) is dried, the urethane resin (A) and the polyisocyanate crosslinking agent (B) are thermally crosslinked, so that an ultraviolet curable pressure-sensitive adhesive sheet having excellent shape retention is obtained. It is done. Moreover, when the said (meth) acrylic compound (C) contains a hydroxyl group, it crosslinks with the said urethane resin (A) through the said polyisocyanate crosslinking agent (B). As a result, the curing proceeds more efficiently when irradiated with ultraviolet rays to be described later, so that an ultraviolet curable pressure-sensitive adhesive sheet having excellent moisture and heat whitening resistance can be 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.

  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, and 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 resin (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.

As the cured product layer of the ultraviolet curable pressure-sensitive adhesive sheet, the storage elastic modulus at 30 ° C. is 1 × 10 ⁴ Pa or more when measured at a frequency of 1 Hz, from the point that the moisture and heat whitening resistance can be further improved. preferable. In addition, the measuring method of the storage elastic modulus of the said adhesive sheet is described in an Example.

Moreover, as the said adhesive sheet, it is preferable that the storage elastic modulus in 80 degreeC and 100 degreeC is 1 * 10 < ⁴ > Pa or more when measured at a frequency of 1 Hz from the point which can improve moisture-heat whitening resistance further. In addition, the measuring method of the storage elastic modulus of the said adhesive sheet is described in an Example.

  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 Resin Solution (A-1)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 287 parts by mass of polyoxypropylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PPG”), 2-hydroxyethyl 0.8 parts by mass of acrylate (hereinafter abbreviated as “HEA”), 31 parts by mass of 1,4-hexanedimethanol (hereinafter abbreviated as “CHDM”), and 1.6 of 2,6-ditertiary butyl cresol. 1 part by mass, 0.2 parts by mass of p-methoxyphenol and 150 parts by mass of ethyl acetate 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, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after hold | maintaining at 75 degreeC for 12 hours, 136 mass parts of ethyl acetate is added, and it stirs and cools until it becomes uniform for 30 minutes after that, a non volatile matter; 60 mass%, weight average molecular weight: 39,000, hydroxyl group content A urethane resin solution (A-1) having an amount of 0.032 mol / kg and an acryloyl group content of 0.016 mol / kg was obtained.

[Synthesis Example 2]
<Synthesis of urethane resin solution (A-2)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 205 parts by mass of PPG, 1.32 parts by mass of HEA, 42 parts by mass of CHDM, and 1,6-ditertiary butylcresol 1. 1 part by mass, 0.2 parts by mass of p-methoxyphenol and 150 parts by mass of ethyl acetate were added. After raising the temperature in the reaction vessel to 40 ° C., 110 parts by mass of IPDI was added. Therefore, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after hold | maintaining at 75 degreeC for 12 hours, 89 mass parts of ethyl acetate is added, and it stirs and cools until it becomes uniform for 30 minutes after that, a non volatile matter; 60 mass%, weight average molecular weight: 32,000, content of a hydroxyl group A urethane resin solution (A-2) having an amount of 0.032 mol / kg and an acryloyl group content of 0.032 mol / kg was obtained.

[Synthesis Example 3]
<Synthesis of urethane resin solution (A-3)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 274 parts by mass of polyoxytetramethylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PTMG”) and 1 HEA .1 part by mass, 20 parts by mass of 1,4-butanediol (hereinafter abbreviated as “1,4BG”), 1.1 parts by mass of 2,6-ditertiary butylcresol, p-methoxyphenol 2 parts by mass and 150 parts by mass of ethyl acetate were added. After raising the temperature in the reaction vessel to 40 ° C., 109 parts by mass of IPDI was added. Therefore, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after hold | maintaining at 75 degreeC for 12 hours, 119 mass parts of ethyl acetate was added, and it stirred and cooled until it became uniform for 30 minutes after that, a non volatile matter; 60 mass%, weight average molecular weight: 35,000, content of a hydroxyl group A urethane resin solution (A-3) having an amount of 0.048 mol / kg and an acryloyl group content of 0.048 mol / kg was obtained.

[Synthesis Example 4]
<Synthesis of urethane resin solution (A-4)>
Polycarbonate polyol (“Duranate T5651” manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight; 1,000, hereinafter abbreviated as “PC”) is added to a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer. 262 parts by mass, HEA 0.75 parts by mass, CHDM 35 parts by mass, 2,6-ditertiary butyl cresol 1.1 parts by mass, p-methoxyphenol 0.2 parts by mass, ethyl acetate 150 parts by mass were added. . After raising the temperature in the reaction vessel to 40 ° C., 110 parts by mass of IPDI was added. Therefore, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after holding at 75 ° C. for 12 hours, 122 parts by mass of ethyl acetate was added, and then stirred and cooled until uniform for 30 minutes. Nonvolatile content: 60% by mass, weight average molecular weight: 33,000, hydroxyl group content An urethane resin solution (A-4) having an amount of 0.032 mol / kg and an acryloyl group content of 0.016 mol / kg was obtained.

[Synthesis Example 5]
<Synthesis of urethane resin solution (A-5)>
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube and thermometer, 264.5 parts by mass of PPG, 0.6 parts by mass of HEA, 34 parts by mass of CHDM, 2,6-ditertiary butyl cresol 1.1 parts by mass, 0.2 parts by mass of p-methoxyphenol, and 150 parts by mass of ethyl acetate were added. After raising the temperature in the reaction vessel to 40 ° C., 109 parts by mass of IPDI was added. Therefore, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after hold | maintaining at 75 degreeC for 12 hours, 122 mass parts of ethyl acetate was added, and it stirred and cooled until it became uniform for 30 minutes after that, a non volatile matter; 60 mass%, weight average molecular weight: 19,000, hydroxyl group content An urethane resin solution (A-5) having an amount of 0.10 mol / kg and an acryloyl group content of 0.0125 mol / kg was obtained.

[Synthesis Example 6]
<Synthesis of urethane resin solution (A-6)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 286 parts by mass of PPG, 1.24 parts by mass of HEA, 30.5 parts by mass of CHDM, 2,6-ditertiary butylcresol 1.1 parts by mass, 0.2 parts by mass of p-methoxyphenol, and 150 parts by mass of ethyl acetate were added. After raising the temperature in the reaction vessel to 40 ° C., 110 parts by mass of IPDI was added. Therefore, 0.05 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 75 ° C. over 1 hour. Then, after hold | maintaining at 75 degreeC for 12 hours, 135 mass parts of ethyl acetate is added, and it stirs and cools until it becomes uniform for 30 minutes after that, a non volatile matter; 60 mass%, weight average molecular weight: 29,000, hydroxyl group content An urethane resin solution (A-7) having an amount of 0.025 mol / kg and an acryloyl group content of 0.025 mol / kg was obtained.

[Example 1]
<Preparation of UV-curable adhesive composition>
In a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 100 parts by mass of the urethane resin (A-1) and 10 parts by mass of trimethylolpropane triacrylate (“Aronix M-309” manufactured by Toagosei Co., Ltd.) The mixture was stirred until uniform. Thereafter, the mixture was cooled to room temperature and 0.5 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (hereinafter abbreviated as “(E-1)”) and bis (2,2,6) decanedioate with stirring. , 6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester and 0.5 parts by mass of triphenylphosphine were sequentially added and stirred until uniform. Furthermore, 1 part by mass of hexamethylene diisocyanate (HDI) isocyanurate was added and stirred until uniform, followed by filtration through a 200 mesh wire netting to obtain an ultraviolet curable pressure-sensitive adhesive composition.

[Examples 2 to 8]
Except for changing the type and / or amount of the urethane resin (A) used and the polyisocyanate crosslinking agent (B) and (meth) acrylic compound (C) as shown in Tables 1-2 In the same manner as in Example 1, an ultraviolet curable adhesive composition was obtained.

[Comparative Example 1]
An ultraviolet curable pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 1 part by mass of the HDI nurate compound was changed to 0 part 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 trimethylolpropane triacrylate 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 K7361-1-1997. 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 7361-1-1997. Evaluated.
“◯”: The difference in haze (%) values before and after the wet heat resistance test is less than 0.3%.
“Δ”: The difference in haze (%) value before and after the wet heat resistance test is 0.3% or more and less than 1.0%.
"X": The difference in haze (%) values before and after the wet heat resistance test is 1% or more.

[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.
“◯”: The area magnification of the pressure-sensitive adhesive sheet after being left is less than 103%.
“Δ”: The area magnification of the pressure-sensitive adhesive sheet after being left is 103% or more and less than 105%.
“X”: The area magnification of the pressure-sensitive adhesive sheet after being left is 105% 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 permeation | transmission of a glass plate might be 1 J / cm < ² >, and the laminated body which has an adhesive sheet was obtained. The obtained laminate was allowed to stand for 24 hours in an atmosphere of 80 ° C., and the inner part of a 50 μm thick frame was visually observed, and the followability to a 50 μm step was evaluated as follows.
“◯”: There is no floating from the step and no bubbles are mixed.
“Δ”: There is no lift from the step, but bubbles are slightly mixed.
“X”: There is no lift from the step, but a part of the bubbles is confirmed.

Abbreviations in Tables 1 and 2 will be described.
"Trimethylolpropane adduct of TDI"; trimethylolpropane adduct of toluene diisocyanate)
“Trimethylolpropane adduct of XDI”; trimethylolpropane adduct of xylylene diisocyanate)
“Mixture of PETA and PETEA”; mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (“Aronix M-305” manufactured by Toa Gosei Co., Ltd.)
“1,6-HDDA”; 1,6-hexanediol diacrylate

  It turned out that Examples 1-8 which are the ultraviolet curable adhesive composition of this invention are excellent in heat-and-moisture whitening resistance, level | step difference followability, and shape retention property.

  On the other hand, although the comparative example 1 is an aspect which does not use a polyisocyanate crosslinking agent (B), shape retention property was unsatisfactory.

  Although the comparative example 2 is an aspect which does not use a (meth) acrylic compound (C), moisture-and-heat whitening resistance is inferior and level | step difference followability is also inadequate.

Claims (10)

A urethane resin (A) having a hydroxyl group and a (meth) acryloyl group, a polyisocyanate crosslinking agent (B), a (meth) acrylic compound (C) having two or more (meth) acryloyl groups, an organic solvent (D), and 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 urethane resin (A) is made from a polyol (a1) containing a polyether polyol and / or a polycarbonate polyol. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the content of the hydroxyl group in the urethane resin (A) is in the range of 0.01 to 0.5 mol / kg. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the content of the (meth) acryloyl group in the urethane resin (A) is in the range of 0.005 to 0.5 mol / kg. 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 according to claim 1, wherein the polyisocyanate crosslinking agent (B) is used in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the solid content of the urethane resin (A). Composition. 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. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the amount of the (meth) acrylic compound (C) used is in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the solid content of the urethane resin (A). object. 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 8 on a substrate. Production method. A method for producing a laminate, which is obtained by bonding at least two adherends with the ultraviolet curable pressure-sensitive adhesive sheet according to claim 9 and then irradiating with ultraviolet rays.