KR20160070143A - Photocurable adhesive composition, adhesive sheet and laminate - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive which is capable of suppressing the generation of bubbles without using a heat treatment or a pressurizing treatment in the process of bonding to the surface of the substrate having unevenness, and is excellent in adhesive strength and optical characteristics. (B) a monofunctional monomer having a cyclic structure in an amount of 10 to 50 parts by mass, (D) a photopolymerization initiator in an amount of 0.1 to 10 parts by mass, and (E) a heat crosslinking agent in an amount of 0.5 to 100 parts by mass based on 100 parts by mass of the (meth) By mass to 10 parts by mass of the curable pressure-sensitive adhesive composition.

Description

TECHNICAL FIELD [0001] The present invention relates to a photocurable adhesive composition, a pressure-sensitive adhesive sheet and a laminate,

The present invention relates to a photocurable pressure-sensitive adhesive composition, and a pressure-sensitive adhesive sheet and a laminate using the same.

The pressure-sensitive adhesive is widely used when bonding parts together. For example, an optical member for the purpose of surface protection and display performance improvement is adhered to an image display unit such as a display of a cellular phone terminal or a computer, and an adhesive sheet for adhering an optical member has been developed .

The adhered surface of an adherend such as an image display unit or an optical member is not flat and there are cases where unevenness exists. As a result, there is a problem that when the adhesive sheet and the adherend are bonded to each other, voids (bubbles) are generated between the adhesive sheet and the adherend at or near the uneven portions.

In order to solve such a problem, Patent Documents 1 to 3 disclose a pressure-sensitive adhesive sheet with improved step traceability.

Japanese Patent Application Laid-Open No. 2010-163591 Japanese Patent Application Laid-Open No. 2011-184582 Japanese Patent Application Laid-Open No. 2013-040256

However, the pressure-sensitive adhesive sheets disclosed in Patent Documents 1 to 3 apply heat and / or pressure to follow the pressure-sensitive adhesive sheet to the unevenness. That is, in the conventional pressure sensitive adhesive sheet, heat treatment, pressure treatment, and the like are required in the step of bonding the pressure sensitive adhesive sheet to the adherend.

In view of the above problems, it is an object of the present invention to provide a process for bonding a substrate surface having unevenness, which can suppress generation of bubbles without using a heat treatment or a pressure treatment, (Optical characteristics) of a pressure-sensitive adhesive.

The present invention provides the following photocurable pressure-sensitive adhesive composition, and a pressure-sensitive adhesive sheet and a laminate using the same.

(1) A thermosetting resin composition comprising (A) a (meth) acrylic polymer, (B) a monofunctional monomer having a cyclic structure, (D) a photopolymerization initiator, and (B) the content of the monofunctional monomer having a cyclic structure is 10 to 50 parts by mass, the content of the photopolymerization initiator (D) is 0.1 to 10 parts by mass, the content of the thermosetting agent (E) 0.5 to 10 parts by mass.

(2) A photopolymerizable composition comprising (A) a (meth) acrylic polymer, (B) a monofunctional monomer having a cyclic structure, (C) a hydrophilic monofunctional monomer, (D) a photopolymerization initiator, and (B) the content of the monofunctional monomer having a cyclic structure is 10 to 50 parts by mass, the content of the hydrophilic monofunctional monomer (C) is 1 to 15 parts by mass based on 100 parts by mass of the (meth) acrylic polymer (A) , The content of the photopolymerization initiator (D) in the range of 0.1 to 10 parts by mass, and the content of the thermosetting agent (E) in the range of 0.5 to 10 parts by mass.

[3] The photocurable pressure-sensitive adhesive composition according to the above [1] or [2], wherein the monofunctional monomer (B) having a cyclic structure has a dicyclopentadiene structure.

[4] The photocurable pressure-sensitive adhesive composition according to any one of [1] to [3], which does not contain a polyfunctional monomer.

[5] The positive resist composition according to any one of [1] to [4], wherein the (A) (meth) acrylic polymer contains repeating units derived from a (meth) acrylic acid ester monomer as a main repeating unit and further contains a hydroxyl group and / Sensitive adhesive composition according to any one of the above [1] to [4], wherein the photocurable pressure-sensitive adhesive composition contains a repeating unit derived from a polymerizable monomer.

[6] The photocurable pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the hydroxyl value of the (meth) acrylic polymer (A) and / or the acid value is from 5 to 100.

[7] The photopolymerizable pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the (A) (meth) acrylic polymer has a glass transition temperature of -50 ° C to 0 ° C and a weight average molecular weight of 100,000 to 500,000. Composition.

[8] The photocurable pressure-sensitive adhesive composition according to [2], wherein the hydrophilic monofunctional monomer (C) has a hydroxyl group or an alkoxyalkyl group.

[9] The photocurable pressure-sensitive adhesive composition according to any one of [1] to [8], wherein the photopolymerization initiator (D) has an acylphosphine oxide structure.

[10] The photocurable pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the heat crosslinking agent (E) comprises a polyisocyanate compound and / or an epoxy compound.

[11] (F) The photocurable pressure-sensitive adhesive composition according to any one of [1] to [10], further comprising a silane coupling agent.

[12] The photocurable pressure-sensitive adhesive composition according to any one of [1] to [11], wherein the pressure-sensitive adhesive layer has a dielectric constant of 5 F / m or less.

[13] A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed by the photocurable pressure-sensitive adhesive composition according to any one of [1] to [12], and a substrate to which the pressure-sensitive adhesive layer is bonded.

[14] A laminate having at least one layer of the pressure-sensitive adhesive layer and / or the substrate laminated on the pressure-sensitive adhesive sheet according to [13] above.

The photocurable pressure-sensitive adhesive composition of the present invention is capable of inhibiting the generation of air bubbles without using a heat treatment or a pressurizing treatment in the process of bonding to the surface of the substrate having unevenness and also provides a pressure-sensitive adhesive excellent in adhesive strength and optical properties can do.

The pressure-sensitive adhesive sheet and laminate using the photocurable pressure-sensitive adhesive composition of the present invention can suppress generation of air bubbles, and can exhibit excellent adhesive strength and optical characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an embodiment of a pressure-sensitive adhesive sheet of the present invention. Fig.

Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following embodiments, but can be modified, modified, and improved without departing from the scope of the present invention.

In the present specification, the term "photocurable pressure-sensitive adhesive composition", "pressure-sensitive adhesive sheet" and "laminate" are simply referred to as "photocurable pressure-sensitive adhesive composition of the present invention" Laminated body "

1. Photocurable adhesive composition

The photocurable pressure sensitive adhesive composition contains (A) a (meth) acrylic polymer, (B) a monofunctional monomer having a cyclic structure, (D) a photopolymerization initiator, and (E) a thermal crosslinking agent. (B) the content of the monofunctional monomer having a cyclic structure is from 10 to 50 parts by mass, the content of the photopolymerization initiator (D) is from 0.1 to 50 parts by mass, and the content of the photopolymerization initiator is from 0.1 to 50 parts by mass based on 100 parts by mass of the (meth) 10 parts by mass, and the content of the thermosetting agent (E) is 0.5 to 10 parts by mass.

Since the photocurable pressure-sensitive adhesive composition (B) contains a monomer such as a monofunctional monomer having a cyclic structure, the fluidity of the (A) (meth) acrylic polymer is improved in the photocurable pressure-sensitive adhesive composition, . As a result, the photocurable pressure-sensitive adhesive composition can be adhered to the surface of the adherend without following the step (conformity to steps) of the concavo-convex shape without forming voids, even when the adherend is a substrate having concavo- The photocurable pressure-sensitive adhesive composition of the present invention exhibits satisfactory step-wise followability when bonded to an adherend even under the conditions of normal temperature and pressure. That is, in order to improve the step-following ability, a heating treatment or a pressurizing treatment is not required.

Refers to a property that the pressure-sensitive adhesive composition adheres to irregularities existing on the surface of an adherend in a state of close contact without adhering to the surface of an adherend so that the occurrence of voids (bubbles) can be suppressed .

The stepwise follow-up rate of the photocurable pressure-sensitive adhesive composition is preferably 25% or more, more preferably 38% or more, further preferably 50% or more. In addition, the photocurable pressure-sensitive adhesive composition of the present invention achieves the above stepwise follow-up rate without performing heat treatment or pressure treatment at the time of bonding with an adherend.

Refers to the ratio (percentage) of the step height at which the photocurable pressure-sensitive adhesive composition can form the pressure-sensitive adhesive layer without generating voids (air bubbles) and the thickness of the pressure-sensitive adhesive layer Step following rate = step height / pressure-sensitive adhesive layer thickness). That is, a pressure-sensitive adhesive layer having a thickness of 100 占 퐉 (or a pressure-sensitive adhesive layer having a thickness of 100 占 퐉 provided on the pressure-sensitive adhesive sheet) can be bonded to the surface of a substrate having a convex portion , The step coverage rate is defined as 50% from the ratio of the step difference of 50 mu m to 100 mu m of the pressure-sensitive adhesive layer. For example, in the case of a step difference of 100 占 퐉 and a pressure-sensitive adhesive layer of 150 占 퐉, the step coverage rate is 67%; In the case of the step 25 m, the pressure-sensitive adhesive layer 50 m, the step 50 m, the pressure-sensitive adhesive layer 100 m or the step 100 m, and the pressure-sensitive adhesive layer 200 m, the step coverage is 50%; When the step is 12 占 퐉, the pressure-sensitive adhesive layer is 50 占 퐉, the step is 25 占 퐉, the pressure-sensitive adhesive layer is 100 占 퐉, or the step is 50 占 퐉 and the pressure-sensitive adhesive layer is 200 占 퐉, the step coverage rate is 25%.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an embodiment of a pressure-sensitive adhesive sheet of the present invention. Fig. 1 shows a pressure-sensitive adhesive layer 1 adhered to be sandwiched between substrates (adherends) 2 of two layers. 1, convex portions (stepped portions) 3 are provided on a substrate (adherend) 2 adhered on the upper side of the pressure-sensitive adhesive layer 1. [ Here, the height h of the convex portion 3 is set such that the height h from the surface of the substrate on which the convex portion 3 is provided to the portion (vertex) at which the convex portion 3 protrudes most Quot; length " The thickness T of the pressure-sensitive adhesive layer (1) is the length of the pressure-sensitive adhesive layer in a direction perpendicular to the surface of the pressure-sensitive adhesive layer (surface bonded to the substrate).

Since the photocurable pressure-sensitive adhesive composition contains (B) a monomer such as a monofunctional monomer having a cyclic structure and (D) a photopolymerization initiator, the photopolymerization initiator (D) in the photocurable pressure- Species may be generated to cause radical polymerization of the monomers. Further, in the photocurable pressure-sensitive adhesive composition of the present invention, since it is cured by light irradiation such as ultraviolet rays, acid is less likely to be generated as compared with the conventional photocurable pressure-sensitive adhesive composition which requires the involvement of cationic polymerization. Further, in the photocurable pressure-sensitive adhesive composition of the present invention, heat treatment is not required for curing. As a result, the photocurable pressure-sensitive adhesive composition of the present invention can be preferably used for an object having poor corrosiveness or heat resistance.

By polymerization of such a monomer, the photocurable pressure-sensitive adhesive composition is photo-cured and changes from an adhesive state to an adhesive state. The photocurable pressure-sensitive adhesive composition of the present invention has a high adhesive force after photo-curing and is also excellent in the high temperature (about 80 to 90 ° C) environment, but at high temperature (about 60 to 90 ° C) The adhesive force after the photo-curing is hardly changed significantly. That is, the photocurable pressure-sensitive adhesive composition of the present invention has high adhesive strength and excellent heat resistance and heat and humidity resistance.

In particular, since the photocurable pressure-sensitive adhesive composition (B) contains a monofunctional monomer having a cyclic structure in a predetermined content, the curing shrinkage after photo-curing is small, and the deterioration of the adhesion of the photocurable pressure-sensitive adhesive composition to an adherend can be suppressed .

(A) a (meth) acryl-based polymer and (E) a heat-curable pressure-sensitive adhesive composition containing a thermosetting agent (E) The crosslinking agent is crosslinked, and the processability can be exerted. Here, "processability" refers to the property that the shape of the coated film is retained during winding of the pressure-sensitive adhesive sheet before UV curing, cutting, punching, and the like. For example, when the substrate coated with the photocurable pressure-sensitive adhesive composition is cut at a cross section including the substrate and the coating film, the coating film of the photocurable pressure-sensitive adhesive composition does not come out from the end face, It is said to have no properties. The photocurable pressure-sensitive adhesive composition exhibits good processability even when it contains monomers by curing after application. That is, the adhesive does not come out at the time of processing, and it can follow the unevenness of the surface of the adherend at the time of bonding. Although the step-following property and processability are contradictory, the photocurable pressure-sensitive adhesive composition of the present invention can be compatible with them.

The photocurable pressure-sensitive adhesive composition may further contain (C) a hydrophilic monofunctional monomer. In this case, the content of the hydrophilic monofunctional monomer (C) is 1 to 15 parts by mass based on 100 parts by mass of the (A) (meth) acrylic polymer. When the photocurable pressure-sensitive adhesive composition further comprises (C) a hydrophilic monofunctional monomer, the water content in the pressure-sensitive adhesive layer is increased, and the whitening of the pressure-sensitive adhesive layer can be suppressed even in the case of immersion under high temperature and high humidity conditions.

In the photocurable pressure-sensitive adhesive composition, the viscosity at 25 ° C is preferably 100 to 20,000 mPa · s, more preferably 500 to 6000 mPa · s. In the photocurable pressure-sensitive adhesive composition of the present invention, when the viscosity is within the above-mentioned range, the pressure-sensitive adhesive layer can be formed satisfactorily because coating can be easily performed and the step following property can be improved and the formation of voids There is an advantage to be able to do.

The pressure-sensitive adhesive layer preferably has a dielectric constant of 5 F / m or less, more preferably 4 F / m or less, and further preferably 3.5 F / m or less. The lower limit value of the permittivity of the pressure-sensitive adhesive layer is not particularly limited, but is usually 2 F / m or more.

Hereinafter, each component of the photocurable pressure-sensitive adhesive composition will be described in more detail.

1-1. (A) a (meth) acrylic polymer

(A) (meth) acrylic polymer means a polymer containing a repeating unit derived from a (meth) acrylic monomer in the main chain.

As used herein, the term "(meth) acrylic monomer" means acrylic acid, methacrylic acid, or a salt or ester thereof.

Specific examples of the "(meth) acrylic monomers" used in the present specification include, for example, (meth) acrylic acid salts such as ammonium (meth) acrylate, sodium (meth) acrylate and potassium (meth) acrylate; Propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (Meth) acrylates having 1 to 20 carbon atoms in the alkyl group such as lauryl (meth) acrylate and cyclohexyl (meth) acrylate; (Meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and 4-hydroxybutyl Acrylic acid esters; (Meth) acrylamides such as (meth) acrylamide; Polyfunctional monomers such as hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate and trimethylolpropane tri (meth) acrylate.

Among the polymers containing the repeating unit derived from the (meth) acrylic monomer, the (A) (meth) acrylic polymer preferably contains a repeating unit derived from a (meth) acrylic acid ester monomer as a main repeating unit in the main chain, More preferably contains repeating units derived from ethyl acrylate, butyl acrylate, and / or 2-ethylhexyl acrylate as main repeating units, and more preferably contains repeating units derived from ethyl acrylate and / or butyl acrylate as main repeating units Most preferably in terms of units. (A) (meth) acrylic polymer as the main repeating unit, it becomes possible to exhibit good adhesion property and adhesion property. Incidentally, "containing as the main repeating unit" means that the repeating unit in the polymer contains 60 mass% or more of the total repeating units. The content of the repeating units in the polymer is preferably 80% by mass or more, more preferably 90 to 100% by mass, based on the total of all the repeating units.

In the photocurable pressure-sensitive adhesive composition of the present invention, the (A) (meth) acrylic polymer does not require that all repeating units are repeating units derived from a (meth) acrylic monomer. That is, it may contain a repeating unit other than the repeating unit derived from the (meth) acrylic monomer to further enhance the effect of the present invention.

There is no particular limitation on the kind of the "monomer other than the" (meth) acrylic monomer "derived from the repeating unit in the (meth) acrylic polymer (A), and examples thereof include monomers having a polymerizable unsaturated bond.

Specific examples of the "monomers other than the (meth) acrylic monomers" include (meth) acrylonitriles such as (meth) acrylonitrile; Aromatic vinyls such as styrene and? -Methylstyrene; Vinyl carboxylates such as vinyl acetate and vinyl propionate; unsaturated dicarboxylic acids such as maleic anhydride, itaconic acid and fumaric acid; And N-vinyl lactams such as N-vinyl pyrrolidone and N-vinyl caprolactam.

As the "monomer other than the" (meth) acrylic monomer ", a monomer having a hydrophilic group copolymerizable with the (meth) acrylic acid ester monomer is preferable. Specifically, a monomer having a hydroxyl group, a carboxyl group, an alkoxyalkyl group and a sulfonyl group is preferable, and a monomer having a hydroxyl group, a carboxyl group and an alkoxyalkyl group is more preferable, and a monomer having a hydroxyl group and / or a carboxyl group is particularly preferable. (A) a (meth) acrylic polymer and (E) a thermal cross-linking agent by adding a repeating unit derived from the above-mentioned (meth) acrylic polymer to a monomer other than the " (meth) acrylic monomer & . (E) a hydroxyl group concentration not reacted with the thermal cross-linking agent is 2 to 98 KOH mg / g in terms of the hydroxyl value, whereby the resistance to humidity and humidity can be improved. A more preferred range of the hydroxyl value is 2 to 85 KOHmg / g, and a particularly preferable range is 5 to 65 KOHmg / g. Further, the adhesiveness of the pressure-sensitive adhesive to the adherend can be improved by containing 2 to 90 KOH mg / g of the carboxyl group concentration not reacted with the heat crosslinking agent (E) as an acid value (carboxyl group). A more preferred range of the acid value is 2 to 65 KOHmg / g, and a particularly preferable range is 2 to 40 KOHmg / g. If it is out of the above range, there is a fear that the moisture resistance is lowered.

On the other hand, as the "monomers other than the" (meth) acrylic monomers ", from the viewpoint of the optical properties of suppressing the coloring of the pressure-sensitive adhesive and improving the transparency, the repeating units derived from (meth) acrylonitrile, Is preferably 5% by mass or less of the total repeating units in the (A) (meth) acrylic polymer.

The (A) (meth) acrylic polymer may have a photoconductive portion within a range not adversely affecting the adhesion performance. The content of the photocrosslinking moiety is preferably 10 mol or less, more preferably 3 mol or less, per 1 mol of the polymer (A), more preferably 3 mol or less, And particularly preferably 1.5 mol or less.

As the photo-crosslinkable moiety that the (A) (meth) acrylic polymer may have, a "side chain having a radically polymerizable unsaturated bond" may be mentioned. Examples of the "side chain having a radically polymerizable unsaturated bond" include an acryloyl group and a methacryloyl group [so-called (meth) acryloyl group functional group]. In the pressure-sensitive adhesive composition of the present invention, it is preferable that the polymer (A) has an acryloyl group in view of being capable of imparting excellent polymerizability (further ultraviolet curable property) It is preferable to have a methacryloyl group. The (meth) acryloyl group-containing functional group is not necessarily a functional group having a structure in which an acryloyl group or a methacryloyl group can be directly bonded to a main chain, and an acryloyl group or a methacryloyl group Or may be a functional group having a structure capable of indirectly bonding to the main chain through any atom or functional group (for example, acryloyloxy group, etc.). In the pressure-sensitive adhesive composition of the present invention, the "(meth) acryloyl group having a structure capable of indirectly bonding to the main chain" corresponding to the "side chain having a radically polymerizable unsaturated bond" that the polymer (A) (Trade name: CALENS MOI, manufactured by Showa Denko K.K.) or 2-acryloyloxyethyl isocyanate (trade name: CALENSE AOI, manufactured by Showa Denko K.K.) and 2- (2-methacryloyloxyethyl isocyanate Methacryloyloxyethyl) ethyl isocyanate (trade name: CALENS MOIEG, manufactured by Showa Denko K.K.).

In the present specification, "hydroxyl value" means the number of mg of potassium hydroxide required for acetylating the hydroxyl group contained in 1 g of the sample. Acetic anhydride is used to acetylate the hydroxyl groups in the sample, and the unused acetic acid is titrated with potassium hydroxide solution. In the present specification, the "acid value" means the number of mg of potassium hydroxide required to neutralize the acidic group contained in 1 g of the sample.

The glass transition temperature (Tg) of the (A) (meth) acrylic polymer is preferably -50 ° C to 0 ° C, more preferably -40 ° C to -10 ° C, and more preferably -40 ° C to -20 ° C desirable. By setting the glass transition temperature (Tg) of the (A) (meth) acryl-based polymer to -50 캜 or higher, it is possible to improve workability and prevent the pressure-sensitive adhesive from being discharged. Further, it is possible to suppress a decrease in adhesive strength after photo-curing. On the other hand, by setting the glass transition temperature (Tg) of the (A) (meth) acryl-based polymer to 0 캜 or less, it is possible to suppress the lowering of the step following property and suppress the remarkable deterioration of the heat-

(A) the glass transition temperature (Tg) of the polymer, (A) the solution containing the polymer is spread on a glass plate and dried at 100 DEG C for 2 minutes The dried film was measured by a differential scanning calorimeter (trade name: DSC, manufactured by Rigaku Denki Co., Ltd.) under a nitrogen atmosphere at a heating rate of 20 ° C / min and a sample amount of 20 mg Quot; means a value of the glass transition temperature (Tg).

The weight average molecular weight of the (A) (meth) acrylic polymer is preferably from 100,000 to 500,000, more preferably from 100,000 to 400,000, and particularly preferably from 150,000 to 350,000. By setting the weight average molecular weight of the (A) (meth) acryl-based polymer to 100,000 or more, it is possible to improve the processability and suppress the pressure-sensitive adhesive from being discharged. Further, it is possible to suppress a decrease in adhesive strength after photo-curing. On the other hand, when the weight average molecular weight of the (meth) acrylic polymer (A) is 500,000 or less, it is possible to suppress the degradation of the stepwise followability.

In the present specification, the term "weight average molecular weight" means a weight average molecular weight value in terms of polystyrene measured by a GPC method (gel filtration chromatography method).

1-2. (B) a monofunctional monomer having a cyclic structure

(B) a monofunctional monomer having a cyclic structure is provided with flowability to the photo-curable pressure-sensitive adhesive composition before photo-curing to improve the step-following ability and at the same time, by irradiating light, (D) a radically active species generated from a photopolymerization initiator To give a high adhesive strength to the pressure-sensitive adhesive.

The monofunctional monomer (B) having a cyclic structure has a cyclic structure and has a single-walled property, so that good adhesion with an adherend can be maintained since curing shrinkage after photo-curing is small.

Examples of the "cyclic structure" of the monofunctional monomer (B) having a cyclic structure include a dicyclopentadiene structure such as a dicyclopentenyl group, an adamantane structure such as an adamantyl group, and a borane structure such as an isobornyl group , More preferred are a dicyclopentadiene structure and a borane structure, and a dicyclopentadiene structure is particularly preferable. By having a cyclic structure such as a dicyclopentadiene structure, curing shrinkage can be suppressed.

Specific examples of monofunctional monomers having a cyclic structure (B) include isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, 2- (Meth) acrylate, tricyclo [5.2.1.0 (2,6)] dec-3-en-8 or 9-yloxy) ethyl- (meth) acrylate, tricyclo [5.2 .1.0 (2,6)] dec-8-yl- (meth) acrylate. These monofunctional monomers may be used singly or in combination of two or more.

The content of the monofunctional monomer (B) having a cyclic structure in the photocurable pressure-sensitive adhesive composition is preferably from 10 to 50 parts by mass, more preferably from 15 to 45 parts by mass, more preferably from 20 to 50 parts by mass, based on 100 parts by mass of the (A) 40 < / RTI > When the content of the (B) monofunctional monomer having a cyclic structure is 10 parts by mass or more, it is possible to provide a sufficient step-following property and improve the adhesive strength after photo-curing. On the other hand, by setting the content of the (B) monofunctional monomer having a cyclic structure to 50 parts by mass or less, the release of the pressure-sensitive adhesive can be suppressed and the workability can be improved.

1-3. (C) a hydrophilic monofunctional monomer

(C) The hydrophilic monofunctional monomer can increase the water content in the pressure-sensitive adhesive, and can suppress clouding of the pressure-sensitive adhesive layer even under high-temperature and high-humidity conditions or immersion.

As the hydrophilic monofunctional monomer (C), monofunctional monomers having a hydroxyl group or an alkoxyalkyl group are preferable. Specific examples include hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxybutyl (meth) acrylate; (Meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, ethoxyethoxyethyl (Meth) acrylic ester monomers and vinyl ether monomers having an alkylene oxide structure such as polyethylene glycol (meth) acrylate. These monofunctional monomers may be used singly or in combination of two or more.

As the hydrophilic monofunctional monomer (C), among these, hydrophobicity of the pressure-sensitive adhesive is preferably suppressed as the side chain is longer. For example, the number of carbon atoms in the side chain is preferably 4 or more.

The content of the hydrophilic monofunctional monomer (C) in the photocurable pressure-sensitive adhesive composition is preferably 1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and still more preferably 2.5 to 7.5 parts by mass relative to 100 parts by mass of the (A) Is more preferable. By controlling the content of the hydrophilic monofunctional monomer (C) to not less than 1 part by mass and not more than 15 parts by mass, it is possible to suppress the fluctuation of the optical characteristics (Hz, b *) of the pressure-sensitive adhesive layer during white turbidity and wet heat treatment.

1-4. Other monofunctional monomers

The photocurable pressure-sensitive adhesive composition may contain a monofunctional monomer other than the monofunctional monomer (B) having a cyclic structure and the hydrophilic monofunctional monomer (C). In the following specification, these monofunctional monomers are collectively referred to as " other monofunctional monomers ".

Other monofunctional monomers are monofunctional and are not particularly limited so long as they do not impair the characteristics of the photocurable pressure-sensitive adhesive composition of the present invention. (Meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate and the like, in addition to acrylic acid and methacrylic acid. ) Acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl oligoacrylate, isobornyl acrylate, phenoxyethyl acrylate, phenoxypolyethylene glycol acrylate, 2-hydroxy (Meth) acrylate esters such as 3-phenoxypropyl acrylate; (Meth) acrylate esters having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; Vinyl carboxylates such as vinyl acetate and vinyl propionate; Aromatic vinyls such as styrene and? -Methylstyrene; Acrylamides such as acryloylmorpholine, N-vinyl-2-pyrrolidone, hydroxyethyl acrylamide, dimethyl acrylamide, dimethylaminoethyl acrylate methyl chloride quaternary salt, and dimethylaminopropylacrylamide; 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyl (Meth) acryloxyalkoxysilanes such as triethoxysilane, and vinylalkoxysilanes. These monofunctional monomers may be used singly or in combination of two or more.

1-5. (D) a photopolymerization initiator

(D) The photopolymerization initiator generates radical active species upon irradiation with light, thereby causing polymerization of monomers such as (B) a monofunctional monomer having a cyclic structure and (C) a hydrophilic monofunctional monomer.

(D) the photopolymerization initiator is not particularly limited. For example, it is possible to use an α-hydroxyacetophenone (trade name: Irgacure 184, BASF), α-aminoacetophenone, a benzoin compound and an acylphosphine oxide compound [for example, 819 (trade name, manufactured by BASF), Lucirin TPO (trade name, manufactured by BASF), and the like. These photopolymerization initiators may be used singly or in combination of two or more.

(D) The photopolymerization initiator is preferably a photopolymerization initiator having an acylphosphine oxide structure (hereinafter referred to as " photopolymerization initiator ") having an acylphosphine oxide structure Hereinafter referred to as " acylphosphine oxide type phosphorus photopolymerization initiator ") is preferable.

Specifically, the acylphosphine oxide type photopolymerization initiator (D) which can be used as the photopolymerization initiator (D) is a radical polymerizable photopolymerization initiator having the above-mentioned properties, Having an acylphosphine oxide structure.

(D) When an acylphosphine oxide type photopolymerization initiator is used as a photopolymerization initiator, the structures other than the acylphosphine oxide structure in the structure of the acylphosphine oxide type photopolymerization initiator are not particularly limited, A structure capable of adding optimum physical properties may be appropriately selected depending on the performance (ultraviolet curing property, color, etc.) required for the pressure-sensitive adhesive composition.

(D) In the acylphosphine oxide type photopolymerization initiator which can be used as a photopolymerization initiator, examples of the structure other than the acylphosphine oxide structure include a benzoin structure, a hydroxyacetophenone structure, an aminoacetophenone structure, Include those contained in the structure of another photopolymerization initiator, called a benzophenone structure.

(D) Acylphosphine oxide type photopolymerization initiator which can be used as a photopolymerization initiator includes a polymer photopolymerization initiation system in which an acylphosphine oxide structure is introduced into a polymer compound. When the acylphosphine oxide type photopolymerization initiator that can be used as the photopolymerization initiator (D) corresponds to a polymer photopolymerization initiator, the acylphosphine oxide type photopolymerization initiator is a polymer (weight average molecular weight is about 50,000 or more) , And an oligomer (having a weight average molecular weight of about 500 to 50,000).

Specific examples of the acylphosphine oxide type photopolymerization initiator which can be used as the photopolymerization initiator (D) include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (trade name: Irgacure 819, BASF Trimethyl-pentylphosphine oxide (trade name: CGL403, manufactured by BASF), 2,4,6-trimethylbenzoyl-2,6-dimethoxybenzoyl- And at least one selected from the group consisting of diphenylphosphine oxide (trade name: Irgacure TPO, BASF), and more preferably at least one selected from the group desirable. These photopolymerization initiators may be used singly or in combination of two or more.

(D) As the acylphosphine oxide type phosphorus-containing photopolymerization initiator which can be used as a photopolymerization initiator, it is preferable to use a photopolymerization initiator having excellent curability and capable of suppressing a change in color tone of a coating film formed from the photopolymerizable pressure- , 6-trimethylbenzoyl-diphenylphosphine oxide are particularly preferable.

The content of the photopolymerization initiator (D) in the photocurable pressure-sensitive adhesive composition is 0.1 to 10 parts by mass, preferably 0.25 to 7.5 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the (A) Do. By setting the content of the photopolymerization initiator (D) to 0.1 part by mass or more, polymerization of the monomer in the photocurable pressure-sensitive adhesive composition can be promoted. On the other hand, when the content of the photopolymerization initiator (D) is 10 parts by mass or less, deterioration of optical properties such as coloration and transparency of the pressure-sensitive adhesive layer can be suppressed.

1-6. (E) Heat crosslinking agent

(A) (meth) acrylic polymer and (E) thermal cross-linking agent can be crosslinked when the pressure-sensitive adhesive layer (E) and the pressure-sensitive adhesive sheet (E) are cured (room temperature or heated). When bonded to the surface of the adherend, good fluidity is imparted to the photocurable pressure-sensitive adhesive composition.

(E) The heat crosslinking agent is not particularly limited, and examples thereof include polyfunctional isocyanate compounds, epoxy compounds, melamine compounds, metal salt compounds, metal chelate compounds, amino resin compounds, peroxides and the like. Above all, an aliphatic or aromatic adduct type or nourishing type isocyanate type compound is preferable. Specifically, as a commercially available product, "Coronate", trade name, manufactured by Nippon Polyurethane Industry Co., Ltd. can be used. The thermal crosslinking agents may be used alone or in combination of two or more.

The content of the heat crosslinking agent (E) in the photocurable pressure-sensitive adhesive composition is preferably 0.5 to 10 parts by mass, more preferably 0.75 to 7.5 parts by mass, and more preferably 1.0 to 5.0 parts by mass, relative to 100 parts by mass of the (meth) desirable. By setting the content of the heat crosslinking agent (E) to 0.5 part by mass or more, it is possible to suppress the release of the pressure-sensitive adhesive and improve the workability. On the other hand, when the content of the heat-crosslinking agent (E) is 10 parts by mass or less, it is possible to provide a sufficient step-following property and improve the adhesive strength after photo-curing.

1-7. (F) Silane coupling agent

The photocurable pressure-sensitive adhesive composition may further comprise (F) a silane coupling agent. (F) The silane coupling agent improves the adhesiveness of the pressure-sensitive adhesive sheet and suppresses the decrease in the bonding strength under high temperature and high humidity conditions.

As the silane coupling agent (F), a typical silane coupling agent may be used without particular limitation. Specific examples thereof include alkylalkoxysilane and the like. Among them, it is preferable to use a silane coupling agent having a functional group such as a glycidoxy group, a methacryloxy group, or an acryloxy group for the purpose of improving adhesion to a glass substrate such as a front plate of a plasma display. (Trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), γ-glycidoxypropyltriethoxysilane (trade name: KBE-403 (Meth) acryloyloxypropyltrimethoxysilane,? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like), γ-glycidoxypropylmethyldimethoxysilane, γ- Ethoxy silane, and the like. These silane coupling agents may be used singly or in combination of two or more kinds.

The content of the silane coupling agent (F) in the photocurable pressure-sensitive adhesive composition is preferably 0.25 to 10 parts by mass, more preferably 0.5 to 7.5 parts by mass, and more preferably 1.0 to 5.0 parts by mass based on 100 parts by mass of the (A) Mass part is more preferable. When the content of the silane coupling agent (F) is 0.25 parts by mass or more, the heat and humidity resistance can be made sufficient. On the other hand, by setting the content of the silane coupling agent (F) to 10 parts by mass or less, it is possible to suppress a decrease in the adhesive strength of the adhesive sheet after photo-curing.

1-8. solvent

In addition to the components described above, a solvent may be further added to the photocurable pressure-sensitive adhesive composition. The solvent is not particularly restricted but includes, for example, aromatic solvents such as toluene and xylene; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and 2-methyl-5-hexanone; Ester solvents such as ethyl acetate, butyl acetate and ethyl lactate; Halogen solvents such as methyl chloride, dichloromethane and dichloroethane; And glycol ether solvents such as ethylene glycol ethyl ether, propylene glycol methyl ether, propylene glycol-n-propyl ether and propylene glycol methyl ether acetate. The solvent may be used alone, or two or more solvents may be used in combination.

In the case of using a solvent, the content of the solvent in the photocurable pressure-sensitive adhesive composition can be appropriately adjusted depending on the applicability, workability, etc. of the objective photocurable pressure-sensitive adhesive composition.

1-9. Other additives

The photocurable pressure-sensitive adhesive composition may contain, in addition to the components described above, ultraviolet absorbers, light stabilizers, antioxidants, antifoaming agents, leveling agents, antistatic agents, surfactants, storage stabilizers, heat polymerization inhibitors, plasticizers, wettability improvers, A tackifier, a curing agent, a dye, a dye, a pigment, a thixotropic agent, a filler, and the like may be further added as needed. The amount of various additives such as ultraviolet absorbers listed here can be appropriately determined as needed within a range that does not impair the purpose of the photocurable pressure-sensitive adhesive composition of the present invention.

2. Adhesive sheet

The pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer formed by the above-mentioned photocurable pressure-sensitive adhesive composition of the present invention and a substrate to which the pressure-sensitive adhesive layer is bonded. This pressure-sensitive adhesive sheet is provided with a pressure-sensitive adhesive layer formed by the photocurable pressure-sensitive adhesive composition of the present invention described above, so that the occurrence of bubbles is suppressed and the adhesive strength is also excellent. The " sheet " in this specification means a sheet, and for example, a tape or a film is also included in the " sheet "

The material of the base material in the adhesive sheet is not particularly limited. As the material of the base material usable in the pressure-sensitive adhesive sheet of the present invention, for example, a synthetic resin such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PO (polyolefin), a film thereof, glass, metal, . The thickness of the substrate in the pressure-sensitive adhesive sheet of the present invention is not particularly limited. For example, in the case of providing thin film or flexibility, the thickness of the film is preferably 5 to 300 탆, more preferably 25 to 200 탆 And particularly preferably 50 to 150 mu m.

 Since the pressure-sensitive adhesive layer provided on the pressure-sensitive adhesive sheet is formed by the above-mentioned photocurable pressure-sensitive adhesive composition of the present invention, even when the object is exposed to high temperature and high humidity, it has sufficient heat resistance and heat and humidity resistance, The adhesive strength) and the optical characteristics are hardly changed. The pressure-sensitive adhesive layer provided on the pressure-sensitive adhesive sheet of the present invention is effectively cured by irradiation with ultraviolet rays and changes from an adhesive state to an adhesive state. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 5 to 300 占 퐉, more preferably 25 to 200 占 퐉, and particularly preferably 50 to 150 占 퐉.

The pressure-sensitive adhesive sheet can be produced, for example, as follows. First, the base material and the like are prepared as the base material of the adhesive sheet. Next, the photocurable pressure-sensitive adhesive composition of the present invention as described above is prepared, and the photocurable pressure-sensitive adhesive composition is coated on at least one surface of the substrate by a coating and spreading apparatus such as an applicator, dried, A pressure-sensitive adhesive sheet can be obtained. The curing is not particularly limited, but it can be heated (kept at) for 24 hours to 240 days, for example, at 25 to 80 占 폚. By this curing, the crosslinking reaction between the (A) (meth) acrylic polymer and the (E) thermal crosslinking agent in the photocurable pressure-sensitive adhesive composition can be promoted.

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet of the present invention is excellent in the step following property, the adhesive property, and the optical property characteristic, even when a substrate having a step such as a convex portion is used as an adherend, Can be balanced and exhibit excellent performance as compared with the conventional pressure sensitive adhesive.

The pressure-sensitive adhesive sheet is cured by irradiating the pressure-sensitive adhesive layer to adhere to the substrate by changing the state of adhesion with the bonded substrate to an adhesive state. The light to be irradiated is not particularly limited, but may be appropriately selected from ultraviolet ray, electron beam and the like depending on the type of the photopolymerization initiator (D).

The amount of integrated light required when the pressure-sensitive adhesive layer provided on the pressure-sensitive adhesive sheet is cured by light irradiation to change from the pressure-applied state to the adhered state varies depending on the ultraviolet ray, the thickness of the pressure-sensitive adhesive layer on the substrate surface, . It is not particularly limited, for example, 10 to which it is preferably 4000mJ / cm ^2, and the 50 to 2000mJ / cm ² is not preferred, and particularly preferred from 100 to 1000mJ / cm ^2. If the accumulated amount of ultraviolet light is in the range of 10 to 4000 mJ / cm ² , it is effectively cured by irradiation with ultraviolet rays, and the adhesive force can be sufficiently increased. As a light source of ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, an arc lamp, a gallium lamp and the like can be used.

3. Laminate

The laminate of the present invention is a laminate including the above-mentioned pressure-sensitive adhesive sheet of the present invention. A pressure-sensitive adhesive layer may be further laminated on at least one side of the pressure-sensitive adhesive sheet, or the substrate may be further laminated. The substrate and the pressure-sensitive adhesive layer may be further laminated on at least one side of the pressure-sensitive adhesive sheet. Further, the pressure-sensitive adhesive layer or substrate to be laminated need not necessarily have the same composition or shape as the pressure-sensitive adhesive layer or substrate of the pressure-sensitive adhesive sheet, but may be different.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(1) Acrylic polymer

(Synthesis Example)

For each of the acrylic polymers (A-1) to (A-4), monomer mixtures were prepared by mixing the respective monomers in the formulations shown in Table 1, and 100 parts by mass of the monomer mixture, 150 parts by mass of ethyl acetate, And 2 parts by mass of nitrile were put into a four-necked flask and reacted at 70 DEG C for 8 hours under a nitrogen atmosphere and further reacted at 80 DEG C for 1 hour. Acrylic polymers (A-1) to (A-4) were obtained as polymers containing ethyl acetate solution.

The abbreviations for each monomer shown in Table 1 are as follows.

BA: butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

EA: Ethyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

2EHA: 2-ethylhexyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

ISTA: Isostearyl acrylate (manufactured by Osaka Yuzugaku Kogyo Co., Ltd.)

MMA: methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

AA: Acrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.)

AN: acrylonitrile (manufactured by Wako Pure Chemical Industries, Ltd.)

HEA: hydroxyethyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

HEMA: hydroxyethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

MOI: 2-methacryloyloxyethyl isocyanate [manufactured by Showa Denko K.K.]

(Synthesis Example of Acrylic Polymer Having Introduced Light (Ultraviolet) Crosslinking Site)

, 0.01 part of a reaction catalyst (dibutyltin laurate), 2 parts of 2-methacryloyloxyethyl isocyanate (trade name: CALENS MOI, Showa Co., Ltd.) was added to 100 parts of the acrylic polymer (composition ratio of A- 0.08 part), and the mixture was heated to 40 占 폚 while stirring. The reaction was terminated by titration analysis at the time when disappearance of the isocyanate group could be confirmed by the titration analysis to obtain a modified (meth) acrylic polymer (Acryl-based polymer (A-3)). The reaction time was 5 hours from the start of the dropwise addition of the mixed solution. The acrylic polymer (A-6) was synthesized in the same manner as the acrylic polymer (A-3) except that the acrylic polymer (A-4) was used as the starting acrylic polymer.

[Glass transition temperature (Tg)]:

The solution containing the acrylic polymer (A-1) was spread on a glass plate and dried at 100 DEG C for 2 minutes to obtain a dried film. The obtained dry film was measured for glass transition temperature (Tg) under the conditions of a temperature elevation rate of 20 占 폚 / min and a sample amount (20 mg) in a nitrogen atmosphere using a differential scanning calorimeter (trade name: DSC, Rigaku Denki Co., Respectively. The glass transition temperature (Tg) (占 폚) measured in this manner was regarded as the glass transition temperature (Tg) (占 폚) of the acrylic polymer (A-1). The glass transition temperatures (Tg) (占 폚) of the acrylic polymers (A-2) to (A-4) were measured in the same manner. The results are shown in the column of " Tg (占 폚) "

[Weight average molecular weight]:

Average molecular weight in terms of polystyrene measured by GPC method (gel filtration chromatography). The weight average molecular weights of the acrylic polymers (A-1) to (A-4) are shown in "Mw" in Table 1.

(2) The cyclic monomer

The following cyclic monomers (B-1) to (B-3) were used.

B-1: 2- (tricyclo [5.2.1.0 (2,6)] dec-3-en-8 or 9-yloxy) ethyl- acrylate (FA512AS, manufactured by Hitachi Kasei Corporation)

B-2: tricyclo [5.2.1.0 (2,6)] dec-8-yl-acrylate (FA513AS, manufactured by Hitachi Kasei Corporation)

B-3: Isobornyl acrylate ("IBXA" manufactured by Osaka Kikin Kagaku Kogyo Co., Ltd.)

(3) Hydrophilic monomer

The following hydrophilic monomers (C-1) to (C-3) were used.

C-1: ethoxyethoxyethyl acrylate ("V # 190 etc." manufactured by Osaka Kikin Kagaku Kogyo Co., Ltd.)

C-2: 4-Hydrobutyl acrylate ("4HBA" made by Osaka Kikin Kagaku Kogyo Co., Ltd.)

C-3: 2-ethylhexyl-diglucol acrylate ("EHDG-AT" manufactured by Kyowa Chemical Industry Co., Ltd.)

(4) Other monomers

Other monomers (other-1) to (other-4) shown below were used.

Others-1: Acryloylmorpholine (ACMO manufactured by Kojin)

Others -2: Tetrahydrofurfuryl acrylate ("V # 150" manufactured by Osaka Kikin Kagaku Kogyo Co., Ltd.)

Others -3: 3-isocyanatopropyltriethoxysilane (KBE-9007, manufactured by Shin-Etsu Chemical Co., Ltd.)

Others-4: tricyclodecane dimethanol diacrylate ("A-DCP" manufactured by Shin-Nakamura Chemical Co., Ltd.)

(5) Photopolymerization initiator

The following photopolymerization initiators (D-1) to (D-2) were used.

D-1: Hydroxyacetophenone ("Irg184" manufactured by BASF)

D-2: 2,4,6-Trimethylbenzoyldiphenylphosphine oxide ("DAROCURE TPO" made by BASF)

(6) Heat-crosslinking agent

Thermal crosslinking agents (E-1) to (E-2) shown below were used.

E-1: Trimethylolpropane-tolylene diisocyanate trimer adduct ("Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.)

E-2: Trimethylolpropane polyglycidyl ether ("Denacol EX-321L" manufactured by Nagase ChemteX)

(7) Silane coupling agent

The following silane coupling agent (F-1) was used.

F-1: 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.)

(Examples 1 to 11 and Comparative Examples 1 to 5)

[Preparation of photocurable pressure-sensitive adhesive composition]

The acrylic polymer, the cyclic monomer, the hydrophilic monomer, the other monomer, the photopolymerization initiator, the thermal crosslinking agent and the silane coupling agent described above for the photocurable pressure-sensitive adhesive compositions of Examples 1 to 11 and Comparative Examples 1 to 5 are shown in Tables 2 and 3 And 100 parts by mass of methyl ethyl ketone as a solvent was added and mixed. In Table 2 and Table 3, numerical values representing the mixing ratio represent " part by mass ". The "mass part" in the "examples" is a value obtained by making the acrylic polymer 100 parts by mass unless otherwise specified. Further, in Table 2 and Table 3, the numerical values indicated by " - " means those not contained in the photocurable pressure-sensitive adhesive composition.

As to the photocurable pressure-sensitive adhesive compositions of the examples and the comparative examples, a pressure-sensitive adhesive sheet was prepared as described below, and a pressure-sensitive adhesive sheet was subjected to a series of tests.

[Production of adhesive sheet]:

The above-mentioned photocurable pressure-sensitive adhesive composition was used as a coating solution as it was, and the coating solution was applied to the surface of a release PET film (release film) by an applicator and dried at 100 ° C for 2 minutes. By curing for 3 days, a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having a thickness of about 100 탆 was superimposed was obtained. A PET film (100 탆 thick) was used as the substrate.

[Initial (room temperature) adhesion before UV irradiation]:

The peeled films of the pressure-sensitive adhesive sheets of Examples and Comparative Examples were peeled off and bonded to a glass plate and allowed to stand at room temperature (23 占 폚) for 30 minutes and then subjected to 180 占 peeling test according to JIS Z0237, And the peeling speed was 300 mm / min. The results are shown in the tables "Before UV irradiation", "Adhesion (N / 25 mm)" and "Initial" in Tables 2 and 3. The evaluation criteria are as follows (not shown in the table).

1.5 (N / 25mm) or less: Excellent

1.5 (N / 25mm) or more and less than 3 (N / 25mm): Good

3 (N / 25mm) or more: Bad

[Adhesive residue resistance (re-releasability)]:

The photocurable pressure-sensitive adhesive compositions of each of Examples and Comparative Examples were evaluated for residual adhesive resistance (re-releasability). Specifically, the adhesive remnant resistance was evaluated by observing the exfoliation mark when the initial (room temperature) adhesive force before UV irradiation was measured. The evaluation results are shown below in Table 2 and Table 3 in the column of "before UV irradiation", "adhesive force (N / 25 mm)" and "residual adhesive resistance (re-releasability)".

Remaining adhesive: Excellent

Adhesive residue slightly: Good

Remaining adhesive: bad

[Step Followability]:

A pressure-sensitive adhesive sheet for evaluating the step-following property was produced in accordance with the above-mentioned [preparation of pressure-sensitive adhesive sheet]. The pressure-sensitive adhesive sheet for evaluation of step-like followability was bonded to a glass plate on which a provisional step made of PET was disposed. At the time of bonding, the ultraviolet rays (UV) from the weight of 2kg, glass plate a roller having a diameter of 100mm, (PET malleable car,) the pressure-sensitive adhesive layer, after the above laminate of the PET film reciprocating so as to attain joining once, the condition of 500mJ / cm ² And the coating film was ultraviolet cured. After 72 hours from the adhesion, the presence or absence of pores (bubbles) in the vicinity of the false tip was confirmed. The above operation was repeated by changing the height of the tip end taper, and the difference in height of the tapered end (step coverage ratio (%)) was determined for each of the photocurable adhesive compositions of Examples and Comparative Examples without causing air bubbles. The evaluation results are shown below in Table 2 and Table 3 in " before UV irradiation " and " step following property ".

Step follow-up rate 50% or more

Step follow-up rate 38% or more and less than 50% (38 ° 가 of tip car height and no air bubbles): Good

Step follow-up rate 25% or more and less than 38% (with a tip height 25 μm and no air bubbles):

Less than 25% follow-up rate (Bottom car height 25 μm with bubble): Not applicable

[Processability]:

The pressure sensitive adhesive sheet of each of the Examples and Comparative Examples was cut, and the presence or absence (amount) of the photocurable pressure sensitive adhesive composition being released from the cut surface of the pressure sensitive adhesive sheet when the load of 0.2 kg per 1 cm ² was applied for 72 hours was evaluated. The evaluation results are shown below in Table 2 and Table 3 under " before UV irradiation " and " processability ".

No emptiness: Excellent

Empty (slightly): Good

Empty Empty (Less Than): Empty

Empty (many): Not allowed

[Initial (room temperature) adhesive force after ultraviolet irradiation]:

Pressure mercury lamp ("Eyeglass Stage ECS-410GX" manufactured by Eyegraphics Co., Ltd.) was placed on the substrate side of the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive sheet of each of Examples and Comparative Examples was bonded to a glass plate, Was irradiated with an ultraviolet ray having an accumulated light quantity of 500 mJ / cm ^{2 by} an ultraviolet ray curing method. After curing, the film was allowed to stand at room temperature (23 DEG C) for 30 minutes, and then the adhesive strength was measured under the conditions of an atmospheric temperature of 23 DEG C and a peeling rate of 300 mm / min by a 180 DEG peeling test method according to JIS Z0237. The results are shown in "After UV irradiation", "Adhesion (N / 25 mm)" and "Initial" in Tables 2 and 3. The evaluation criteria are as follows (not shown in the table).

30 (N / 25mm) or more: Excellent

Less than 20 (N / 25mm) and less than 30 (N / 25mm): Good

Less than 20 (N / 25mm): Bad

[Adhesion of heat-resistant adhesive / anti-wet heat after durability test (heat / wet heat) after ultraviolet irradiation]

Pressure mercury lamp ("Eyeglass Stage ECS-410GX" manufactured by Eyegraphics Co., Ltd.) was placed on the substrate side of the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive sheet of each of Examples and Comparative Examples was bonded to a glass plate, Was irradiated with an ultraviolet ray having an accumulated light quantity of 500 mJ / cm ^{2 by} an ultraviolet ray curing method. The results of measurement of adhesive strength [180 deg. Peel test according to JIS Z0237, atmospheric temperature 23 deg. C, peeling rate 300mm / min under the condition of further treatment at 80 deg. C for 1000 hours after curing by ultraviolet irradiation] In the column of "After UV irradiation", "Adhesion (N / 25 mm)" and "Heat resistance" in Table 3, the adhesive strength [JIS Quot; after UV irradiation "," adhesion force (N / 25 mm) "," adhesion strength (N / 25 mm) "," Wet heat ". The evaluation criteria are as follows (not shown in the table).

100 to 125% of initial (room temperature) adhesive force after ultraviolet irradiation: excellent

125% or more of the initial (room temperature) adhesive force after ultraviolet irradiation, 150% or less or 80% or more, and less than 100: Good

Less than 80% or more than 150% of initial (room temperature) adhesive strength after UV irradiation: Poor

[Optical Hz]:

With respect to the pressure-sensitive adhesive sheets of each of the examples and the comparative examples, a PET film having a pressure-sensitive adhesive layer was bonded to an alkali glass (general hard glass) in the same manner as in the evaluation of the tackiness to form a laminate. The haze of this laminate at 25 캜 was measured by a turbidimeter (hazemeter). Hereinafter, this measurement result may be described as " initial Hz ". The optical Hz was also measured for the laminate after the above-described [durability test after heat radiation (heat and moisture resistance)] was conducted by the same method. The results of each measurement after the initial (normal temperature) and heat resistance tests and after the resistance heating tests are shown in Table 2 and Table 3 for the "initial", "heat resistance", and " Respectively. The evaluation criteria are as follows (not shown in the table).

Early:

Less than 1.0: Good

Above 1.0 and below 1.5: Good

Over 1.5: Not available

After endurance test:

125% or less of the initial (room temperature) optical Hz after ultraviolet irradiation and 1.0 or less: excellent

From more than 125% to less than 150% of the initial (room temperature) optical Hz after ultraviolet irradiation, and more than 1.0 and not more than 1.5: good

Exceeding 150% of the initial (room temperature) optical Hz after UV irradiation, more than 1.5: poor

[Optical b *]:

With respect to the pressure-sensitive adhesive sheets of each of the examples and the comparative examples, a PET film having a pressure-sensitive adhesive layer was bonded to an alkali glass (general hard glass) in the same manner as in the evaluation of the tackiness to form a laminate. The color difference (b *) at 25 deg. C of this laminate was measured by a color difference meter (spectrophotometer). Hereinafter, this measurement result may be described as " initial color difference ". The optical b * was also measured for the laminate after the above-described [durability test after heat radiation (heat and humidity resistant heat)] was conducted by the same method. The results of the measurements after the initial (room temperature) and heat resistance tests and after the resistance heating tests are shown in Table 2 and Table 3 for the "initial", "heat", " Are shown in each column. The evaluation criteria are as follows (not shown in the table).

Early:

0.3 or less: Excellent

0.3 to less than 0.5: Good

Beyond 0.5: Not available

After endurance test:

150% or less of initial (room temperature) optical b * after ultraviolet irradiation and 0.3 or less: excellent

From more than 150% to less than 200% of the initial (room temperature) optical b * after ultraviolet irradiation, and more than 0.3 and less than 0.5: good

Exceeding 200% of the initial (room temperature) optical b * after ultraviolet irradiation and more than 0.5: poor

[Permittivity (F / m)]:

With respect to the pressure-sensitive adhesive sheets of Examples and Comparative Examples, the dielectric constant at 1 MHz was measured using an LCR meter (measurement method). The measurement results are shown in the column of "after UV irradiation" and "dielectric constant (F / m)" in Tables 2 and 3. The evaluation criteria are as follows (not shown in the table).

Below 3.5F / m: Good

Below 3.5 F / m and below 4.5 F / m: Good

4.5 F / m or more and 5 F / m or less:

Above 5F / m: Not possible

(Review)

The photocurable pressure-sensitive adhesive compositions of Examples 1 to 11 showed satisfactory results in step-following property and processability, as well as good adhesive force after UV irradiation, and excellent heat resistance and heat and humidity resistance. In addition, the photocurable pressure-sensitive adhesive compositions of Examples 1 to 11 exhibited satisfactory results in terms of optical properties.

On the other hand, the photocurable pressure-sensitive adhesive compositions of Comparative Examples 1 to 5 were obtained as a result of deteriorated performance of at least one of adhesive strength, step traceability, workability, adhesive strength and optical characteristics. Comparative Example 1 is a photo-curable pressure-sensitive adhesive composition which does not contain (B) a monofunctional monomer having a cyclic structure and (C) a hydrophilic monofunctional monomer, and has excellent step traceability and adhesion. However, Optics b *). Comparative Example 5 was a photocurable pressure-sensitive adhesive composition which did not contain (B) a monofunctional monomer having a cyclic structure, (C) a hydrophilic monofunctional monomer, and (E) a heat crosslinking agent, and was significantly poor in workability and adhesive force.

The present invention can be used as a photocurable pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet using the same, and a laminate. The photocurable pressure-sensitive adhesive composition of the present invention can be used, for example, as a pressure-sensitive adhesive for attaching various optical members to image display parts such as various displays.

1 pressure-sensitive adhesive layer
2 substrate (adherend)
3 step (convex portion)
10 adhesive sheet
h: Height of step (protrusion)
T: thickness of the pressure-sensitive adhesive layer

Claims (14)

(A) a (meth) acrylic polymer,
(B) a monofunctional monomer having a cyclic structure,
(D) a photopolymerization initiator,
(E) a thermosetting agent,
(B) the content of the monofunctional monomer having a cyclic structure is from 10 to 50 parts by mass, the content of the photopolymerization initiator (D) is from 0.1 to 10 parts by mass, and the content of the photopolymerization initiator is from 0.1 to 10 parts by mass based on 100 parts by mass of the (meth) Wherein the content of the thermosetting agent (E) is 0.5 to 10 parts by mass. (A) a (meth) acrylic polymer,
(B) a monofunctional monomer having a cyclic structure,
(C) a hydrophilic monofunctional monomer,
(D) a photopolymerization initiator,
(E) a thermosetting agent,
(B) the content of the monofunctional monomer having a cyclic structure is 10 to 50 parts by mass, the content of the hydrophilic monofunctional monomer (C) is 1 to 15 parts by mass based on 100 parts by mass of the (meth) acrylic polymer (A) , The content of the photopolymerization initiator (D) in the range of 0.1 to 10 parts by mass, and the content of the thermosetting agent (E) in the range of 0.5 to 10 parts by mass. The photocurable pressure-sensitive adhesive composition according to claim 1 or 2, wherein the monofunctional monomer (B) having a cyclic structure has a dicyclopentadiene structure. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 3, which does not contain a polyfunctional monomer. The positive resist composition according to any one of claims 1 to 4, wherein the (A) (meth)
(Meth) acrylic acid ester monomer as a main repeating unit, and further contains a repeating unit derived from
And a repeating unit derived from a hydroxyl group-containing monomer copolymerizable with the (meth) acrylic acid ester monomer and / or a carboxyl group-containing monomer. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the (A) (meth) acrylic polymer has a hydroxyl group and / or an acid value of 5 to 100. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein the (A) (meth) acrylic polymer has a glass transition temperature of -50 ° C to 0 ° C and a weight average molecular weight of 100,000 to 500,000. The photocurable pressure-sensitive adhesive composition according to claim 2, wherein the hydrophilic monofunctional monomer (C) has a hydroxyl group or an alkoxyalkyl group. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 8, wherein the photopolymerization initiator (D) has an acylphosphine oxide structure. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 9, wherein the (E) thermosetting agent comprises a polyisocyanate compound and / or an epoxy compound. 11. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 10, further comprising (F) a silane coupling agent. 12. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive layer has a dielectric constant of 5 F / m or less. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed by the photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 12,
Wherein the pressure-sensitive adhesive layer is bonded to the substrate. A pressure-sensitive adhesive sheet according to claim 13,
Wherein at least one layer of the pressure-sensitive adhesive layer and / or the substrate is further laminated.

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