JP6593147B2 - UV curable adhesive composition - Google Patents

Description

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

  Information display devices such as a liquid crystal display (LCD) and an organic EL display are various devices such as an electronic notebook, a mobile phone, a smartphone, a portable audio player, a PDA, a portable terminal such as a tablet terminal, and a car navigation system. Used in. An information display device mounted on the portable electronic terminal or the like is required to be capable of displaying highly sensitive information in response to further downsizing and thinning of the portable electronic terminal. As the information display device, for example, an information display device having a configuration in which a transparent panel for protecting the information display module is provided on an information display module such as an LCD module or an organic EL module is known. The transparent panel (protective panel) and the information display module are usually fixed by a highly transparent adhesive sheet in many cases. Conventionally, glass panels have been used as the protective panel, but in recent years, cases of using a substrate such as a resin film or a resin plate are increasing in order to reduce the weight of electronic devices.

  However, when these base materials are used as protective panels, gas such as gas and moisture contained in the base material is generated in a humid heat environment, and bubbles are formed at the interface between the base material and the adhesive sheet. As a result, peeling at the interface, a decrease in the sharpness of displayed information, and the like may occur.

  As an adhesive tape that can be used for fixing the protective panel including the base material and the information display module, for example, a predetermined tape that is attached to a transparent panel provided with a decorative portion on one surface of the base material with a predetermined thickness. There is known a double-sided pressure-sensitive adhesive tape for fixing a panel having an acrylic pressure-sensitive adhesive layer having a loss tangent and having an acrylic pressure-sensitive adhesive layer having a predetermined loss tangent attached to the other surface of the substrate on the surface of the image display device. (For example, see Patent Document 1).

  However, in the pressure-sensitive adhesive tape, the gas generated from the base material still exists in the wet heat environment at the interface between the base material and the pressure-sensitive adhesive tape, and bubbles are formed. Could cause.

JP 2013-1769 A

  The problem to be solved by the present invention is to provide an ultraviolet curable pressure-sensitive adhesive composition that provides a pressure-sensitive adhesive tape having excellent adhesive strength and excellent foam resistance that does not generate bubbles at the interface with the adherend. It is.

  The present invention has a hydroxyl group equivalent of 400 g / eq., Including a chain extender having a hydroxyl group (a1-1) and other polyols. It is a reaction product of the following polyol composition (a1), polyisocyanate (a2), and (meth) acryl compound (a3) having an isocyanate group or a hydroxyl group, and the (meth) acryloyl group equivalent is 55,000 g / eq. The urethane (meth) acrylate (A), photopolymerization initiator (B), organic solvent (C), and (meth) acrylic compound (D) having two or more (meth) acryloyl groups are contained. An ultraviolet curable pressure-sensitive adhesive composition is provided.

  The pressure-sensitive adhesive tape obtained from the ultraviolet curable pressure-sensitive adhesive composition of the present invention is excellent in adhesive strength and has excellent foam resistance that does not generate bubbles at the interface with the adherend even in a wet and heat environment. Therefore, even if it is a case where it uses for manufacture of an information display device, it does not cause the fall of the clarity of the information displayed. The pressure-sensitive adhesive tape is also excellent in transparency, step following property, cutting property (= no adhesive residue at the time of cutting) and moisture and heat whitening resistance.

  The ultraviolet curable pressure-sensitive adhesive composition of the present invention contains a chain extender (a1-1) having a hydroxyl group and another polyol, and has a hydroxyl group equivalent of 400 g / eq. It is a reaction product of the following polyol composition (a1), polyisocyanate (a2), and (meth) acrylic compound (a3) having an isocyanate group or a hydroxyl group, and the (meth) acryloyl group equivalent is 55,000 g / eq. Essential components are urethane (meth) acrylate (A), photopolymerization initiator (B), organic solvent (C), and (meth) acrylic compound (D) having two or more (meth) acryloyl groups. It is contained as

  The chain extender (a1-1) having a hydroxyl group is an essential component for obtaining a pressure-sensitive adhesive tape excellent in adhesive force, step following ability and cutting property, and has a number average molecular weight in the range of 50 to 350. . The number average molecular weight of the chain extender (a1-1) is a value measured by the gel permeation chromatography (GPC) method under the following conditions.

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 chain extender (a1-1) include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and 3-methyl-1. , 5-pentanediol, 1,6-hexanediol, 3,3′-dimethylol heptane, neopentyl glycol, 3,3-bis (hydroxymethyl) heptane, diethylene glycol, dipropylene glycol, polyoxypropylene glycol, poly Aliphatic chain extenders such as oxybutylene glycol, glycerin, trimethylolpropane; 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1,4 -Cyclohexanedimethanol, hydro Xylpropylcyclohexanol, tricyclo [5.2.1.0 ^2,6 ] decane-dimethanol, bicyclo [4.3.0] -nonanediol, dicyclohexanediol, bicyclo [4.3.0] nonanedimethanol Chain extension having an alicyclic structure such as, spiro [3.4] octanediol, butylcyclohexanediol, 1,1′-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, 1,3-adamantanediol A chain extender such as an agent can be used. These chain extenders may be used alone or in combination of two or more. As the chain extender (a1-1), those having an alicyclic structure are preferably used from the viewpoint that the adhesive force and cutting property of the pressure-sensitive adhesive tape can be further improved while maintaining excellent step followability. More preferably, 4-cyclohexanedimethanol is used.

  The amount of the chain extender (a1-1) used is preferably in the range of 0.5 to 40% by mass in the polyol composition (a1) from the viewpoint of step following ability and cutting ability. A range of mass% is more preferred.

  Examples of the other polyol include polyether polyol (a1-2), polyester polyol, polycarbonate polyol, polyacryl polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, dimer diol, and polyisoprene polyol. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use a polyether polyol (a1-2) from the viewpoint that the flexibility and wet heat whitening resistance can be further improved.

  Examples of the polyether polyol (a1-2) include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxypropylene poly Oxytetramethylene polyol or the like can be used. These polyether polyols may be used alone or in combination of two or more.

  The amount used in the case of using the polyether polyol (a1-2) is preferably in the range of 10 to 99.5% by mass in the polyol composition (a1) from the viewpoint of flexibility and resistance to moist and heat whitening. The range of 40-95 mass% is more preferable.

  The number average molecular weight of the other polyol is preferably in the range of 400 to 7,000, more preferably in the range of 700 to 4,000, from the viewpoint of step following ability, cutting property, adhesive physical properties, and mechanical strength. preferable. In addition, the number average molecular weight of the said other polyol shows the value measured similarly to the number average molecular weight of the said chain extender (a1-1).

  The hydroxyl group equivalent of the polyol composition (a1) is 400 g / eq. For obtaining excellent adhesive strength, step following ability, and cutting property. It is essential that: By setting within the range of the hydroxyl group equivalent of the polyol composition (a1), the urethane bond in the urethane (meth) acrylate (A) can be increased and the condensing power can be increased. , And cutting properties can be obtained. The hydroxyl group equivalent of the polyol composition (a1) is 50 to 390 g / eq. From the viewpoint that the adhesive force and the cutting property can be further improved while maintaining excellent step following ability. It is preferable that it is the range of 200-300 g / eq. The range of is more preferable. In addition, the hydroxyl group equivalent of the said polyol composition (a1) remove | divides the preparation amount of all the polyols containing the chain extender (a1-1) which has the said hydroxyl group by the total value of the equivalent of each chain extender and polyol. Value.

  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 an alicyclic polyisocyanate from the viewpoint of further improving cutting properties and adhesive properties, and it is composed of 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, and diisocyanate methylcyclohexane. It is more preferable to use one or more polyisocyanates selected from the group.

  The (meth) acrylic compound (a3) 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 (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.

  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, UV curable properties and adhesive properties, and 2-hydroxyethyl acrylate and / or 4-hydroxybutyl acrylate. It is more preferable to use

  As a manufacturing method of urethane (meth) acrylate (A) in the case of using a (meth) acryl compound having an isocyanate group as the compound (a3), for example, the polyol (a1) and the polyisocyanate (in the absence of a solvent) a urethane prepolymer having a hydroxyl group is obtained by charging and reacting with a2), and then the (meth) acrylic compound (a3) having an isocyanate group is supplied, mixed, and reacted to be used. be able to. In any case, the reaction is preferably performed, for example, under a temperature condition of 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 (a3), the said polyol (a1) and the said (meth) under solvent-free, for example. A method in which an acrylic compound (a3) is charged into a reaction system and then the polyisocyanate (a2) is supplied, mixed, and reacted, or the polyol (a1) and the polyisocyanate are prepared without solvent. A urethane prepolymer having an isocyanate group is obtained by reacting with (a2), and then the (meth) acrylic compound (a3) having a hydroxyl group is supplied, mixed, and reacted to be used. Can do. In any case, the reaction is preferably performed, for example, under a temperature condition of 20 to 120 ° C. for 30 minutes to 24 hours.

  The urethane (meth) acrylate (A) may be produced in the presence of an organic solvent (C) described later.

  When the (meth) acrylic compound having a hydroxyl group is used as the compound (a3), the reaction of the polyol composition (a1), the polyisocyanate (a2) and the (meth) acrylic compound (a3) Molar ratio [isocyanate group / total amount of hydroxyl groups] of the total amount of hydroxyl groups possessed by the composition (a1) and the hydroxyl groups possessed by the (meth) acrylic compound (a3) and the isocyanate groups possessed by the polyisocyanate (a2) = It is preferable to carry out in the range of 0.75 to 1 in terms 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 (a3), the reaction between the polyol composition (a1), the polyisocyanate (a2) and the (meth) acrylic compound (a3) Equivalent ratio [total amount of isocyanate groups / hydroxyl group] of the hydroxyl groups of the polyol composition (a1) and the total of isocyanate groups of the polyisocyanate (a2) and the (meth) acrylic compound (a3) = 0.75 It is preferable to carry out in the range of 1 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). .

  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 55,000 g / eq. In order to obtain excellent adhesion, foam resistance, and cutting property. That is essential. Thereby, since it can bridge | crosslink with the (meth) acryl compound (D) mentioned later in the state which the urethane (meth) acrylate (A) intertwined in the ultraviolet curable adhesive composition, the outstanding cohesion force was obtained, and the result It is considered that excellent adhesive strength, foam resistance, and cutting properties are developed. The (meth) acryloyl group equivalent of the urethane (meth) acrylate (A) is from 56,000 to 150,000 g / eq. From the point that adhesive force, foam resistance and cutting property can be further improved. More preferably, it is the range. The (meth) acryloyl group equivalent is the total mass of the polyol (a1), polyisocyanate (a2) and (meth) acrylic compound (a3) in the urethane (meth) acrylate (A). The value divided by the equivalent of the (meth) acryl group is shown.

  As a mass ratio of the urethane bond in the urethane (meth) acrylate (A), 4 to 4 in the total amount of the urethane (meth) acrylate (A) from the viewpoint of further improving the adhesive force, cutting property, and step following property. The range is preferably 20% by mass, and more preferably 5 to 15% by mass. In addition, the urethane bond amount of the said urethane (meth) acrylate (A) occupies in the said raw material with respect to the total mass of the said polyol (a1), the said polyisocyanate (a2), and the said (meth) acrylic compound (a3). The mass ratio of the urethane bond structure is shown.

  The number average molecular weight of the urethane (meth) acrylate (A) is preferably in the range of 23,500 to 50,000 in terms of obtaining even more excellent foam resistance, More preferably, it is in the range of 000. In addition, the number average molecular weight of the said urethane (meth) acrylate (A) shows the value measured similarly to the number average molecular weight of the said chain extender (a1-1).

  In addition, the polydispersity of the urethane (meth) acrylate (A) [weight average molecular weight (Mw) / number average molecular weight (Mn)] is 2.05 or more from the viewpoint that even more excellent foam resistance is obtained. It is preferable that it is in the range of 2.1 to 2.5. The weight average molecular weight of the urethane (meth) acrylate (A) is a value obtained by measurement in the same manner as the number average molecular weight of the chain extender (a1-1), and the polydispersity is obtained. The value calculated from the weight average molecular weight and the number average molecular weight of the urethane (meth) acrylate (A).

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

  Examples of the photopolymerization initiator (B) 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 Anthrax such as thioxanthone, 4,4′-diethylaminobenzophenone, α-acyloxime ester, methylbenzoylformate, 2-ethylanthraquinone Non-compounds; 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 (B), 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 1,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and 1-hydroxycyclohexyl. More preferred are phenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

  As a usage-amount of the said photoinitiator (B), the range which is 0.01-15 mass parts with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can improve ultraviolet sclerosis | hardenability further. It is preferable that the range is 0.05 to 10 parts by mass.

  Examples of the organic solvent (C) 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 (C), it is preferable that it is 70 mass% or less in an ultraviolet curable adhesive composition from the point which can improve drying property and coating property further, and is 5-60 mass%. A range is more preferred.

  Examples of the (meth) acrylic compound (D) having two or more (meth) acryloyl groups include 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-decanediol di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, di (trimethylol group) Bread) di (meth) acrylate, di (trimethylolpropane) tri (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, Aliphatic polyfunctional (meth) acrylates such as dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and tris (2- (meth) acryloyloxyethyl) isocyanurate Polyfunctional (meth) acrylates having an isocyanurate skeleton such as can be used. These (meth) acrylic compounds may be used alone or in combination of two or more. Among these, the polyfunctionality having an aliphatic polyfunctional (meth) acrylate and an isocyanurate skeleton is obtained from the point that improved heat and heat whitening resistance can be obtained by excellent curability with the urethane (meth) acrylate (A). It is preferable to use one or more selected from the group consisting of polyfunctional (meth) acrylates having a (meth) acrylate skeleton, and trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth). It is more preferable to use one or more (meth) acrylic compounds selected from the group consisting of acrylate and tris (2- (meth) acryloyloxyethyl) isocyanurate. The “polyfunctional” means that the (meth) acryloyl group is preferably in the range of 2 to 8, more preferably in the range of 2 to 6.

  As content of the said (meth) acrylic compound (D), the said urethane (meth) from the point which adjusts the crosslinking density with the said urethane (meth) acrylate (A), and the further outstanding level | step difference followability is obtained. It is preferable that it is the range of 1-30 mass parts with respect to 100 mass parts of acrylate (A), and the range of 5-20 mass parts is more preferable.

    The ultraviolet curable pressure-sensitive adhesive composition of the present invention contains the urethane (meth) acrylate (A), the photopolymerization initiator (B), the organic solvent (C), and the (meth) acrylic compound (D). However, it may contain other additives as necessary.

  Examples of the other additives include an antioxidant (E), a light stabilizer (F), a rust inhibitor, a silane coupling agent, a thixotropic agent, a sensitizer, a polymerization inhibitor, a leveling agent, and an adhesive. An imparting agent, 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 in applications requiring high heat and heat yellowing resistance, it contains an antioxidant (E) and a light stabilizer (F). Is preferred.

  Examples of the antioxidant (E) 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 (two Secondary antioxidants) and the like can be used.

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 diphosphite Di (nonylphenyl) pentaerythritol di Sphite, bis (2,4-dibutylphenyl) pentaerythritol diphosphite, bis (2,6-dibutyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4,6-tributylphenyl) pentaerythritol di 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-Jihai Rho-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, phosphite of 2-ethyl-2-butylpropylene glycol and 2,4,6-tributylphenol, 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, laurylylthiodithionate, 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 the adhesive strength and heat and heat yellowing resistance, and triphenylphosphine, bis (2,4-di-tert-butyl-6-methylphenyl) ethylphosphine. It is more preferable to use one or more antioxidants selected from the group consisting of fit and tris (2,4-di-tert-butylphenyl) phosphite, and triphenylphosphine, bis (2,4-di-tert) More preferably, -butyl-6-methylphenyl) ethyl phosphite is used.

  As the usage-amount in the case of using the said antioxidant (E), 0.01-10 mass 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. The range of parts is preferred.

  The light stabilizer (F) captures radicals generated by photodegradation, and includes, for example, radical scavengers such as thiol compounds, thioether compounds and hindered amine compounds; ultraviolet absorbers such as benzophenone compounds and benzoate compounds. Can be used. 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 (F), 0.01-10 mass with respect to 100 mass parts of said urethane (meth) acrylates (A) from the point which can improve a heat-and-moisture yellowing resistance further. The range of parts 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 viscosity meter at 25 degreeC.

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

  The said adhesive tape is obtained by passing through the process of drying the organic solvent (C) in the said ultraviolet curable adhesive composition, and the process of irradiating an ultraviolet-ray and hardening a composition.

  Moreover, as a manufacturing method of the said adhesive tape, from the point from which the adhesive tape excellent in level | step difference followability is obtained, after coating the said ultraviolet curable adhesive composition on a base material, the organic solvent (C) is dried. It is preferable to use a method in which an ultraviolet curable pressure-sensitive adhesive tape is obtained, and then an adhesive layer of the ultraviolet curable pressure-sensitive adhesive tape is attached to a substrate and then irradiated with ultraviolet rays. According to this method, when a substrate having a step such as a printing step is used as a base material to be subsequently attached to the UV curable adhesive tape before UV curing, no gap is left in the step portion. Since the said ultraviolet curable adhesive tape can be affixed to, the adhesive tape which is excellent in level | step difference followable | trackability can be obtained.

  In the present invention, the state after drying of the organic solvent and before ultraviolet curing is referred to as “ultraviolet curing adhesive tape”, and the state after ultraviolet curing is referred to as “adhesive tape”.

  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. In addition, the same base material may be used for both surfaces of the adhesion layer, or different base materials may be used.

  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 method of applying the ultraviolet curable pressure-sensitive adhesive composition to the substrate include a method of applying using an applicator, a roll coater, a knife coater, a gravure coater and the like. After the coating, the obtained laminate is put into a dryer or the like, and the organic solvent (C) is dried by drying at a temperature of 50 to 130 ° C. for 1 to 30 minutes, before ultraviolet curing. An ultraviolet curable adhesive tape is obtained.

The ultraviolet curable pressure-sensitive adhesive tape preferably has a storage elastic modulus at 60 ° C. of less than 3 × 10 ⁵ Pa when measured at a frequency of 1 Hz from the viewpoint of further improving the step following ability. It is preferably ³ or more and less than 3 × 10 ⁵ Pa. In addition, the measuring method of the storage elastic modulus of the said ultraviolet curable adhesive tape is described in an Example.

In addition, the ultraviolet curable adhesive tape has a storage elastic modulus at 30 ° C. of 5 × 10 ⁴ Pa or more when measured at a frequency of 1 Hz because the cutting property and the step following property can be further improved. Is preferable, and the range of 5 × 10 ^{4 to} 5 × 10 ⁶ Pa is more preferable.

The ultraviolet curable adhesive tape has a storage elastic modulus at 80 ° C. of 1 × 10 ^{2 to} 5 × 10 ⁵ Pa when measured at a frequency of 1 Hz because the cutting property and the step following property can be further improved. A range is preferable.

  After the obtained ultraviolet curable pressure-sensitive adhesive tape is attached to the substrate, both may be pressure-bonded and subjected to autoclaving as necessary.

  Thereafter, an adhesive tape is obtained by irradiating with ultraviolet rays. Examples of the method of irradiating with ultraviolet rays include known ultraviolet light irradiation devices such as xenon lamps, xenon-mercury lamps, metal halide lamps, high-pressure mercury lamps, and low-pressure mercury lamps. The method using is mentioned.

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.

  The thickness of the pressure-sensitive adhesive tape obtained by the above method is appropriately determined according to the intended use, but is preferably in the range of about 10 to 500 μm.

Further, examples of the adhesive tape, from viewpoint of further improving the cutting property, the storage elastic modulus at 30 ° C. of preferably 1 × is 10 4 ^Pa or more as measured at a frequency 1 Hz, 1 × 10 ⁴ ~ The range of 5 × 10 ⁷ Pa is more preferable. In addition, the measuring method of the storage elastic modulus of the said adhesive tape is described in an Example.

Further, as the adhesive tape, from viewpoint of further improving the conformability to irregularities, the storage elastic modulus at 80 ° C. of preferably 1 × is 10 4 ^Pa or more as measured at a frequency 1 Hz, 1 × 10 ⁴ A range of ˜1 × 10 ⁷ Pa is more preferable.

Further, as the adhesive tape, from viewpoint of further improving the conformability to irregularities, a storage modulus at 100 ° C. of preferably 1 × is 10 4 ^Pa or more as measured at a frequency 1 Hz, 1 × 10 ⁴ The range of ˜1 × 10 ⁶ Pa is more preferable.

  As described above, the pressure-sensitive adhesive tape obtained from the ultraviolet curable pressure-sensitive adhesive composition of the present invention has excellent adhesive strength and excellent foam resistance that does not generate bubbles at the interface with the adherend even in a wet and heat environment. is there. Therefore, even if it is a case where it uses for manufacture of an information display device, it does not cause the fall of the clarity of the information displayed. Moreover, the said adhesive tape is excellent also in transparency, level | step difference followability, cutting property, and heat-and-moisture whitening property.

  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, 203.3 parts by mass of polypropylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PPG1000”), 2,6- 1.1 parts by mass of di-tertiary butyl-cresol, 0.2 parts by mass of p-methoxyphenol, and 0.7 parts by mass of 2-hydroxyethyl acrylate (hereinafter abbreviated as “HEA”) were added. After raising the temperature in the reaction vessel to 40 ° C., 109.9 parts by mass of isophorone diisocyanate (hereinafter abbreviated as “IPDI”) was added. Therefore, 0.01 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Thereafter, the mixture was held at 80 ° C. for 3 hours, 42 parts by mass of 1,4-cyclohexanedimethanol (hereinafter abbreviated as “CHDM”) was added, and the mixture was held at 80 ° C. for 12 hours. After confirming that all the isocyanate groups had disappeared, the system was cooled to obtain urethane acrylate (A-1). The obtained urethane acrylate (A-1) had an acryloyl group equivalent of 63,100 g / eq. (Rounded to two significant figures. The molecular weight of 2-hydroxyethyl acrylate was 116.1. The same applies hereinafter.), The number average molecular weight was 28,000, and the polydispersity was 2.1. The hydroxyl equivalent of the polyol composition is 250 g / eq. Met.

[Synthesis Example 2]
<Synthesis of urethane acrylate (A-2)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 206.9 parts by mass of PPG1000, 1.1 parts by mass of 2,6-ditertiarybutyl-cresol, p-methoxyphenol 0 2 parts by weight were added. After raising the temperature in the reaction vessel to 40 ° C., 110.5 parts by mass of IPDI was added. Therefore, 0.01 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Then, it hold | maintained at 80 degreeC for 3 hours, 42.4 mass parts of CHDM was added, and it hold | maintained at 80 degreeC for 12 hours. After confirming that all the hydroxyl groups have disappeared, add 0.3 parts by mass of HEA, hold at 80 ° C. for 5 hours, confirm that all the isocyanate groups have disappeared, and then cool to urethane acrylate ( A-2) was obtained. The obtained urethane acrylate (A-2) had an acryloyl group equivalent of 125,000 g / eq. The number average molecular weight was 31,000 and the polydispersity was 2.24. The hydroxyl equivalent of the polyol composition is 250 g / eq. Met.

[Synthesis Example 3]
<Synthesis of urethane acrylate (A-3)>
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube and thermometer, 204.3 parts by weight of PPG1000, 1.1 parts by weight of 2,6-ditertiarybutyl-cresol, p-methoxyphenol 0 2 parts by weight were added. After raising the temperature in the reaction vessel to 40 ° C., 110.4 parts by mass of IPDI was added. Therefore, 0.01 parts by mass of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Then, it hold | maintained at 80 degreeC for 3 hours, 42.2 mass parts of CHDM was added, and it hold | maintained at 80 degreeC for 12 hours. After confirming that all the hydroxyl groups have disappeared, add 0.8 parts by mass of HEA and hold at 80 ° C. for 5 hours. After confirming that all the isocyanate groups have disappeared, cool the urethane acrylate ( A-2) was obtained. The obtained urethane acrylate (A-2) had an acryloyl group equivalent of 56,000 g / eq. The number average molecular weight was 27,000, and the polydispersity was 2.15. The hydroxyl equivalent of the polyol composition is 250 g / eq. Met.

[Comparative 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, 204.0 parts by mass of PPG1000, 1.1 parts by mass of 2,6-ditertiarybutyl-cresol, p-methoxyphenol 0 2 parts by weight were added. After raising the temperature in the reaction vessel to 40 ° C., 109.9 parts by mass of IPDI was added. Therefore, 0.01 part by mass of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Then, it hold | maintained at 80 degreeC for 3 hours, 42.2 mass parts of CHDM was added, and it hold | maintained at 80 degreeC for 12 hours. After confirming that all the hydroxyl groups have disappeared, add 0.9 parts by mass of HEA and hold at 80 ° C. for 5 hours. After confirming that all the isocyanate groups have disappeared, cool the urethane acrylate ( A′-1) was obtained. The obtained urethane acrylate (A′-1) had an acryloyl group equivalent of 45,000 g / eq. The number average molecular weight was 23,000, and the polydispersity was 2.03. The hydroxyl equivalent of the polyol composition is 250 g / eq. Met.

[Comparative Synthesis Example 2]
<Synthesis of urethane acrylate (A'-2)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 203.3 parts by mass of PPG1000, 1.1 parts by mass of 2,6-ditertiarybutyl-cresol, p-methoxyphenol 0 2 parts by weight were added. After raising the temperature in the reaction vessel to 40 ° C., 109.9 parts by mass of IPDI was added. Therefore, 0.01 part by weight of dioctyltin dineodecanate was added, and the temperature was raised to 80 ° C. over 1 hour. Then, it hold | maintained at 80 degreeC for 3 hours, 42.0 mass parts of CHDM was added, and it hold | maintained at 80 degreeC for 12 hours. After confirming that all the hydroxyl groups have disappeared, 1.3 parts by mass of HEA was added and held at 80 ° C. for 5 hours. After confirming that all of the isocyanate groups had disappeared, the system was cooled and urethane acrylate ( A′-2) was obtained. The obtained urethane acrylate (A′-2) had an acryloyl group equivalent of 31,500 g / eq. The number average molecular weight was 21,000 and the polydispersity was 1.98. The hydroxyl equivalent of the polyol composition is 250 g / eq. Met.

[Example 1]
<Preparation of UV-curable adhesive composition>
A reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer was warmed to 80 ° C., and 100 parts by mass of the urethane acrylate (A-1) and 122 parts by mass of ethyl acetate were added and stirred until uniform. Thereafter, the mixture was cooled to room temperature, and 10 parts by mass of trimethylolpropane tri (meth) acrylate (hereinafter abbreviated as “TMPTA”) under stirring, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide (hereinafter referred to as “( B-1) ") is 0.3 parts by mass, and decanedioic acid bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester is 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.

[Examples 2-5, Comparative Examples 1-2]
An ultraviolet curable pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the type and / or amount of urethane (meth) acrylate (A) and (meth) acrylic compound (D) used were changed as shown in Table 1. Obtained.

[Evaluation method of adhesive strength]
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 oil composition was applied, dried in an 80 ° C. drier for 5 minutes, and a release PET 50 was bonded to obtain an ultraviolet curable adhesive tape. Next, the UV curable adhesive tape was UV irradiated with a UV irradiation device so that the integrated light quantity of the wavelength in the UV-A region after passing through the release PET 50 was 1 J / cm ² , thereby producing an adhesive tape. What cut this into 25 mm width was made into the test piece. The test piece was attached to a glass plate or polycarbonate plate (“S300” manufactured by Mitsubishi Plastics, Inc.), which is an adherend, by 2 kg rolls × 2 reciprocations. One hour after pasting, the 180 ° peel strength was measured in an atmosphere of 23 ° C. and 50% RH to obtain an adhesive strength (N / 25 mm).

[Method for evaluating foam resistance]
One side of the pressure-sensitive adhesive tape was bonded to a polyethylene terephthalate film (PET100) having a thickness of 100 μm, and a pressure-sensitive adhesive tape having PET100 bonded to one side was produced. This was cut into a length of 50 mm and a width of 40 mm and affixed to a polycarbonate plate (“S300” manufactured by Mitsubishi Plastics, Inc.) was used as a test piece. This was left for 72 hours in a 100 ° C. atmosphere and then taken out in a 23 ° C., 50% humidity atmosphere. Then, visual observation was performed and evaluated as follows.
"A": There is no bubble, float, and peeling.
“B”: Bubbles are observed in a very small part.
“C”: Air bubbles, floating, or peeling are conspicuous.

[Evaluation method of step following ability]
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 oil composition was applied, dried in an 80 ° C. drier for 5 minutes, and a release PET 50 was bonded to obtain an ultraviolet curable adhesive tape. This was bonded to a polyethylene terephthalate film (PET100) having a thickness of 100 μm to produce an adhesive tape having PET100 bonded to one side. 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. Thereafter, ultraviolet rays were irradiated from the glass plate side so that the integrated light quantity of the wavelength in the UV-A region after dropping the glass plate was 1 J / cm ² to obtain a laminate having an adhesive tape. 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.
"A": There is no floating from a level | step difference, and there is no mixing of a bubble.
“B”: There is no lift from the level difference, but some of the bubbles are mixed.
“C”: Bubbles are conspicuous.

[Evaluation method for resistance to moist heat whitening]
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 oil composition was applied, dried in an 80 ° C. drier for 5 minutes, and a release PET 50 was bonded to obtain an ultraviolet curable adhesive tape. The ultraviolet curable adhesive tape was bonded to a polyethylene terephthalate film (PET100) having a thickness of 100 μm, and an adhesive tape in which PET100 was bonded to one side was produced. This was cut into a length of 50 mm and a width of 40 mm, the release PET 50 was peeled off, and a test piece was attached to a glass plate. Ultraviolet rays were irradiated from the glass plate side of the obtained test piece so that the integrated light quantity of the wavelength in the UV-A region after passing through the glass plate was 1 J / cm ² to obtain a laminate having an adhesive tape. After measuring haze (Haze 1) using a turbidimeter “NDH5000” manufactured by Nippon Denshoku Kogyo Co., Ltd., it was left for 100 hours in an atmosphere of 85 ° C. and 85% humidity, and the temperature was 23 ° C. and 50% humidity. Removed under atmosphere. Within 10 minutes after removal, the haze (haze 2) of the adhesive tape was measured according to JIS K 7361-1-1997 using a turbidimeter “NDH5000” manufactured by Nippon Denshoku Industries Co., Ltd. In addition, when the difference between the haze 1 and the haze 2 is 0.5% or less, “A”, when it exceeds 0.5% and less than 1%, “B”, when it exceeds 1% Was evaluated as “C”.

[Evaluation method of cutting performance]
The ultraviolet curable adhesive film was further bonded to the release PET50. Subsequently, ultraviolet rays were irradiated so that the integrated light amount of the wavelength in the UV-A region was 1 J / cm ² to obtain a laminate having an adhesive film. The obtained laminate was cut with a cutter, and the presence or absence of adhesive residue on the blade of the cutter was visually observed. In addition, when the adhesive residue was not confirmed, it evaluated as "T", and when the adhesive residue was confirmed, it evaluated as "F".

  It was found that the pressure-sensitive adhesive tape obtained from the ultraviolet curable pressure-sensitive adhesive composition of the present invention was excellent in adhesive strength, foam resistance, step following ability, wet heat whitening resistance and cutting property.

  On the other hand, Comparative Examples 1 and 2 are embodiments in which the (meth) acryloyl group equivalent of the urethane (meth) acrylate (A) is less than the range specified in the present invention, but the foam resistance was poor. .

Claims (5)

A hydroxyl group equivalent including a chain extender having a hydroxyl group (a1-1) and other polyol is 400 g / eq. It is a reaction product of the following polyol composition (a1), polyisocyanate (a2), and (meth) acryl compound (a3) having an isocyanate group or a hydroxyl group, and the (meth) acryloyl group equivalent is 55,000 g / eq. The urethane (meth) acrylate (A), photopolymerization initiator (B), organic solvent (C), and (meth) acrylic compound (D) having two or more (meth) acryloyl groups are contained. An ultraviolet curable pressure-sensitive adhesive composition characterized by the above. 2. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the urethane (meth) acrylate (A) has a polydispersity [weight average molecular weight (Mw) / number average molecular weight (Mn)] of 2.05 or more. The ultraviolet curable pressure-sensitive adhesive composition according to claim 1, wherein the chain extender (a1-1) having a hydroxyl group has an alicyclic structure. The ultraviolet curable adhesive composition according to claim 1, wherein the other polyol is a polyether polyol (a1-2). The (meth) acrylic compound (D) is at least one selected from the group consisting of an aliphatic polyfunctional (meth) acrylate and a polyfunctional (meth) acrylate having a polyfunctional (meth) acrylate skeleton having an isocyanurate skeleton. The ultraviolet curable adhesive composition according to claim 1.