KR20170087875A - Active-energy-ray-curable composition, active-energy-ray-curable adhesive composition, adhesive, adhesive sheet, and novel urethane (meth)acrylate - Google Patents

Abstract

An object of the present invention is to provide an active energy ray curable composition containing urethane (meth) acrylate having a low dielectric constant and also excellent compatibility. (Meth) acrylate (A) which is a reaction product of a polyester polyol (a1), a polyisocyanate (a2) and a hydroxyl group-containing (meth) acrylate (a3) And the permittivity of the rate (A) is 7.0 or less.

Description

Active energy ray-curable pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet, and novel urethane (meth) acrylate , and novel urethane (meth) acrylate}

The present invention relates to an active energy ray-curable composition, an active energy ray-curable pressure-sensitive adhesive composition containing the same, and a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet using the active energy ray-curable pressure-sensitive adhesive composition. More particularly, (Meth) acrylate which is low in solubility and also excellent in compatibility.

The present invention also relates to novel urethane (meth) acrylates.

There are various types of pressure-sensitive adhesives such as a strong adhesive pressure-sensitive adhesive for sticking the adherend firmly for a long period of time or a pressure-sensitive adhesive for peeling off the adherend after adhered. Have been designed and used.

BACKGROUND ART Conventionally, examples of the display member, the electronic member, and the pressure sensitive adhesive for optical materials include urethane (meth) acrylate which is obtained by reacting a polyol with a polyisocyanate and a hydroxyl group-containing (meth) acrylate, A pressure-sensitive adhesive was cured. As the polyol, it is well known to use a polyester-based polyol in which a polyhydric carboxylic acid and a polyhydric alcohol are condensed, and in particular, adipic acid as a carboxylic acid (for example, see Patent Document 1).

In recent years, in order to suppress the malfunction of the touch panel caused by the noise generated in the display member and other peripheral members in addition to the tackiness and the humidity resistance, particularly in the application of the optical member, particularly in the case of the touch panel, Is required.

For example, there is disclosed a resin composition for an ultraviolet curable pressure-sensitive adhesive comprising a urethane (meth) acrylate obtained by reacting a hydrogenated polybutadiene polyol, a polyisocyanate and a hydroxyl group-containing (meth) acrylate as a pressure-sensitive adhesive having a low dielectric constant For example, see Patent Document 2).

Patent Document 1 JP 2011-162770 A Patent Document 2 JP 2002-309185 A

However, the urethane (meth) acrylate obtained by reacting a polyester polyol using adipic acid and a polyisocyanate and a hydroxyl group-containing (meth) acrylate disclosed in Patent Document 1 has a high dielectric constant of usually about 8.0, In the case of suppressing the malfunction of the touch panel in the case, the required performance is not satisfied.

The urethane (meth) acrylate obtained by reacting the hydrogenated polybutadiene polyol described in Patent Document 2 with a polyisocyanate and a hydroxyl group-containing (meth) acrylate has a low dielectric constant of usually 3.0 or so, but the hydrogenated polybutadiene polyol has a low polarity The resulting urethane (meth) acrylate itself has a low polarity and has insufficient compatibility with other monomers and resins, so that there is a problem that the degree of freedom in material selection is low or difficult to handle.

Accordingly, an object of the present invention is to provide an active energy ray curable composition containing urethane (meth) acrylate, which has a low dielectric constant and is also excellent in compatibility under such a background. It is also an object of the present invention to provide an active energy ray-curable pressure-sensitive adhesive composition containing the active energy ray-curable composition, a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive sheet, and a novel urethane (meth) acrylate.

As a result of intensive studies in view of such circumstances, the present inventors have found that in an active energy ray curable composition containing a urethane (meth) acrylate obtained by reacting a polyester polyol, the dielectric constant Sensitive adhesive agent having a low dielectric constant and an excellent compatibility can be obtained, thereby completing the present invention.

That is, the gist of the present invention is as follows.

(1) a urethane (meth) acrylate (A) which is a reaction product of a polyester polyol (a1), a polyisocyanate (a2) and a hydroxyl group-containing (meth) acrylate And the permittivity of the rate (A) is 7.0 or less.

[2] The active energy ray-curable composition according to [1], wherein the content X of oxygen atoms in the repeating structural units of the polyester-based polyol (a1) is 0.35 or less. However, the content X is a value represented by the following formula (1).

(1) X = 16c / (12a + b + 16c)

a: the number of carbon atoms in the repeating structural unit of the polyester-based polyol (a1)

b: the number of hydrogen atoms in the repeating structural units of the polyester-based polyol (a1)

c: the number of oxygen atoms in the repeating structural unit of the polyester-based polyol (a1)

[3] The polyester polyol (a1) is a polycondensate of a polyvalent carboxylic acid component containing a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms and a polyhydric alcohol component, Energy radiation curable composition.

[4] The active energy ray-curable composition according to any one of [1] to [3], wherein the polyester-based polyol (a1) has a number average molecular weight of 500 to 12,000.

[5] The active energy ray-curable composition according to any one of [1] to [4], wherein the urethane (meth) acrylate (A) has a weight average molecular weight of 1,000 to 100,000.

[6] The active energy ray-curable composition according to any one of [1] to [5], further comprising an ethylenically unsaturated monomer (B) (excluding the urethane (meth) acrylate .

[7] An active energy ray-curable pressure-sensitive adhesive composition comprising the active energy ray-curable composition according to any one of [1] to [6] above.

[8] A pressure-sensitive adhesive in which the active energy ray-curable pressure-sensitive adhesive composition according to [7] is cured.

[9] A pressure-sensitive adhesive sheet laminated with the pressure-sensitive adhesive according to the above [8], on a base sheet.

(10) A polyester polyol (a1), a polyisocyanate (a2), and a hydroxyl group-containing (meth) acrylate, which are polycondensates of a polyvalent carboxylic acid component containing a polyvalent carboxylic acid component having an alkylene group of 5 to 20 carbon atoms and a polyhydric alcohol component Urethane (meth) acrylate which is the reaction product of the rate (a3).

According to the active energy ray-curable composition of the present invention, a pressure-sensitive adhesive composition having a low dielectric constant and excellent compatibility can be obtained, and a cured pressure-sensitive adhesive is useful as a pressure-sensitive adhesive for an optical member.

Hereinafter, the present invention will be described in detail.

In the present invention, the (meth) acrylic acid is preferably acrylic acid and / or methacrylic acid, the (meth) acrylic is acrylic and / or methacrylic, the (meth) acryloyl is acryloyl and / (Meth) acrylate means acrylate and / or methacrylate, respectively. The acrylic resin is a resin obtained by polymerizing at least one (meth) acrylate monomer, or a polymer obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

In the present specification, " " representing the numerical range is used to mean the numerical values including before and after the lower limit and the upper limit.

The active energy ray curable composition of the present invention comprises urethane (meth) acrylate (A) which is a reaction product obtained by reacting a polyester polyol (a1), a polyisocyanate (a2) and a hydroxyl group containing (meth) acrylate , And the dielectric constant of the urethane (meth) acrylate (A) is 7.0 or less.

Here, the dielectric constant is a value indicating the degree of polarization of a substance when an electric field is applied.

In the present invention, the dielectric constant of urethane (meth) acrylate is defined as the ratio of 1 part by weight of 1-hydroxy-cyclohexyl-phenyl-ketone to 100 parts by weight of urethane (meth) acrylate and an active energy ray- Is a value obtained by measuring the dielectric constant of the cured film obtained by curing. Specifically, it is measured by the following method.

(How to measure)

, 4 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone as a photopolymerization initiator, and a solvent were added to 100 parts by weight of urethane (meth) acrylate to prepare an active energy ray- (PET) film (thickness: 50 mu m) using an applicator and placed in a drier at 60 DEG C for 10 minutes to volatilize the solvent. Thereafter, the surface of the active energy ray-curable composition was laminated from above with an untreated polyethylene terephthalate (PET) film (thickness: 50 mu m), and the laminate was irradiated with ultraviolet rays at 80 W / The cured film was irradiated with ultraviolet rays from the side of the laminate under the condition of cm (high pressure mercury lamp) × 18 cmH × 2.04 m / min × 3 Pass (cumulative dose: 2,400 mJ / cm 2) and cut into 7 cm × 7 cm.

With respect to the test piece for dielectric constant measurement, the electric capacity was measured by applying an electric field at a frequency of 1 MHz with a test piece sandwiched between electrodes using an HP4284A PASSIJON LCR meter (manufactured by Agilent), and from the change in capacitance between the electrodes, The dielectric constant of the composition is calculated.

The urethane (meth) acrylate (A) used in the present invention is a reaction product obtained by reacting a polyester polyol (a1), a polyisocyanate (a2) and a hydroxyl group-containing (meth) acrylate (a3).

Examples of the polyester-based polyol (a1) in the present invention include a polycondensation reaction product (polycondensation product) of a polyhydric alcohol component and a polyvalent carboxylic acid component, a ring-opening polymer of a cyclic ester (lactone) component, and a polyhydric alcohol component , A reaction product by three kinds of components of a polyvalent carboxylic acid component and a cyclic ester component, and the like.

Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 1,3-butanediol diol, 3-trimethylenediol, 1,5-pentamethylene diol, neopentyl glycol, 1,6-hexamethylene diol, Dihydric alcohols such as methylene diol, 1,9-nonanediol, cyclohexane diol (1,4-cyclohexanediol and the like) and bisphenols (bisphenol A and the like), glycerin, trimethylol propane, trimethylol ethane Alcohols, sugar alcohols (such as xylitol and sorbitol), and the like. Of these, dihydric alcohols are preferable from the standpoint of versatility, and ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 2-methyl- Methylene diol and neopentyl glycol are particularly preferred. These may be used alone or in combination of two or more.

Examples of the polyvalent carboxylic acid component include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid; Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and the like; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalene dicarboxylic acid, paraphenylene dicarboxylic acid and trimellitic acid; Of these, aliphatic dicarboxylic acids are preferable, and succinic acid, adipic acid, and sebacic acid are particularly preferable from the viewpoint of less yellowing. These may be used alone or in combination of two or more.

Examples of the cyclic ester component include propiolactone,? -Methyl-? -Valerolactone,? -Caprolactone, and the like.

In the present invention, it is preferable that the content X of the oxygen atom in the repeating structural unit of the polyester-based polyol (a1) as the polyester-based polyol (a1) is 0.35 or less from the viewpoint of low- However, the content X is a value represented by the following formula (1).

(1) X = 16c / (12a + b + 16c)

a: the number of carbon atoms in the repeating structural unit of the polyester-based polyol (a1)

b: the number of hydrogen atoms in the repeating structural units of the polyester-based polyol (a1)

c: the number of oxygen atoms in the repeating structural unit of the polyester-based polyol (a1)

For example, when the polyester polyol (a1) is a copolymer of ethylene glycol and adipic acid, the repeating structural unit is represented by the following structural formula. In the structural formula, n represents the number of repeating structural units.

[Structural formula 1]

In this case, since a = 8, b = 12 and c = 4 in the above formula (1), the content ratio X of oxygen atoms in the repeating structural units represented by the above formula (1) becomes X = 0.37.

From the viewpoint of low dielectric properties, the polyvalent carboxylic acid component constituting the polyester-based polyol (a1) preferably contains a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms, 18, particularly a polyvalent carboxylic acid having an alkylene group having 7 to 16 carbon atoms. It is more preferable that the polyester-based polyol (a1) is a polycondensation product of a polyvalent carboxylic acid component containing a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms and a polyhydric alcohol component.

When the number of carbon atoms in the alkylene group of the polyvalent carboxylic acid is too small, the dielectric constant tends to be high. When the number of carbon atoms is too large, the crystallinity tends to be high and handling becomes difficult.

Specific examples of the polycarboxylic acid having an alkylene group having 5 to 20 carbon atoms include pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanic acid, eicosolic acid, isoeic acid and the like.

When such a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms is used, the polyvalent carboxylic acid is preferably contained in an amount of 10 to 100 mol%, more preferably 20 To 100 mol%, particularly preferably 25 to 100 mol%, and particularly preferably 30 to 100 mol%.

When the content of the polyvalent carboxylic acid having an alkylene group of 5 to 20 carbon atoms in the total of the polyvalent carboxylic acid component is too small, the dielectric constant tends to increase.

The number of hydroxyl groups contained in the polyester-based polyol (a1) is preferably 2 to 5, particularly preferably 2 to 3, and more preferably 2 per one molecule. If the number of hydroxyl groups is too large, gelation tends to occur during the reaction.

The number average molecular weight of the polyester-based polyol (a1) is preferably 500 to 12,000, more preferably 600 to 10,000, and particularly preferably 700 to 8,000.

If the number-average molecular weight is too large, the viscosity tends to be high and the workability tends to deteriorate. When the number average molecular weight is too small, sufficient tackiness tends to be hardly obtained.

The number average molecular weight is a value obtained by the following formula.

In addition, the number of functional groups (F) in the formula represents the number of hydroxyl groups contained in one molecule.

The hydroxyl value of the polyester-based polyol (a1) is preferably from 10 to 400 mgKOH / g, more preferably from 20 to 300 mgKOH / g, and still more preferably from 30 to 250 mgKOH / g. When such a hydroxyl value is too high, the urethane (meth) acrylate tends to have a lower molecular weight and tackiness, while when it is too low, viscosity tends to be lowered and workability tends to be lowered.

The hydroxyl value can be measured based on JIS K 0070-1992.

As the polyisocyanate (a2), for example, tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylene diisocyanate, tetramethyl xylene diisocyanate, phenylene diisocyanate, naphthalene Aromatic polyisocyanates such as diisocyanate and the like, aliphatic polyisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate and lysine triisocyanate, hydrolyzed diphenylmethane diisocyanate, Alicyclic polyisocyanates such as isocyanuric diisocyanate, isobornyl diisocyanate, norbornene diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane, A cyanate compound of a trimer or oligomer compounds, allophanate-type polyisocyanate, buret type polyisocyanate, water dispersion type polyester may be an isocyanate and the like.

Among them, from the viewpoint of excellent stability of reaction, diisocyanate is preferable, and in particular, aliphatic diisocyanate such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate, Alicyclic diisocyanates such as isocyanate, isocyanurate diisocyanate, isophorone diisocyanate, isophorone diisocyanate, norbornene diisocyanate and 1,3-bis (isocyanatomethyl) cyclohexane are preferably used, and more preferably, From this standpoint, water-soluble xylene diisocyanate and isophorone diisocyanate are used. These polyisocyanates may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing (meth) acrylate (a3) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Hydroxyalkyl (meth) acrylates having 2 to 20 carbon atoms (preferably 2 to 18 carbon atoms) of alkyl groups such as 4-hydroxybutyl (meth) acrylate and 6-hydroxyhexyl Hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth) acrylate, dipropylene glycol (meth) acrylate, fatty acid (meth) acrylates such as hydroxyethyl acrylate, hydroxyethyl acryloyl phosphate, 2- (Meth) acrylates such as modified glycidyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2- And one ethylenic unsaturated group such as (Meth) acrylate having two ethylenically unsaturated groups such as glycerin di (meth) acrylate and 2-hydroxy-3-acryloyloxypropyl methacrylate; (Meth) acrylate, caprolactone-modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, caprolactone (Meth) acrylates containing three or more ethylenically unsaturated groups such as modified dipentaerythritol penta (meth) acrylate and ethylene oxide-modified dipentaerythritol penta (meth) acrylate. The hydroxyl group-containing (meth) acrylate (a3) may be used singly or in combination of two or more.

Among them, a hydroxyl group-containing (meth) acrylate having one ethylenic unsaturated group is preferred from the viewpoint of excellent flexibility of the pressure-sensitive adhesive layer, and more preferred are 2-hydroxyethyl (meth) acrylate, 2- (Meth) acrylate such as 2-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 6-hydroxyhexyl Particularly, it is preferable to use 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate in view of excellent reactivity and versatility.

In the present invention, the urethane (meth) acrylate (A) can be produced as follows.

(2) a method in which the polyester polyol (a1), the polyisocyanate (a2) and the hydroxyl group-containing (meth) acrylate (a3) of the (1) (Meth) acrylate (a3) is reacted with the reaction product obtained by previously reacting the polyol (a1) with the polyisocyanate (a2). From the standpoint of the stability of the reaction and the reduction of byproducts The above method (2) is preferred.

The urethane (meth) acrylate (A) is a polyester polyol (a1) which is a polycondensation product of a polyvalent carboxylic acid component containing a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms and a polyhydric alcohol component, a polyisocyanate (meth) acrylate (a2) and a hydroxyl group-containing (meth) acrylate, and the reaction product urethane (meth) acrylate is a novel compound which does not depend on its dielectric constant.

(Meth) acrylate (a3) is reacted with a reaction product obtained by previously reacting a polyester polyol (a1) with a polyisocyanate (a2) in the production of a urethane (meth) acrylate .

For the reaction between the polyester-series polyol (a1) and the polyisocyanate (a2), known reaction means can be used. At this time, by setting the molar ratio of the isocyanate group in the polyisocyanate (a2) to the hydroxyl group in the polyester polyol (a1) to be about 2n: (2n-2) (n is an integer of 2 or more) (Meth) acrylate containing a hydroxyl group-containing (meth) acrylate and a hydroxyl group-containing (meth) acrylate (a3).

Known reaction means can also be used for the addition reaction between the reaction product obtained by previously reacting the polyester polyol (a1) with the polyisocyanate (a2) and the hydroxyl group-containing (meth) acrylate (a3).

The reaction molar ratio of the reaction product to the hydroxyl group-containing (meth) acrylate (a3) is, for example, in the case where the reaction product has two isocyanate groups and the hydroxyl group-containing (meth) acrylate (a3) Reaction product: In the case where the hydroxyl group-containing (meth) acrylate (a3) is about 1: 2 and the isocyanate group of the reaction product is 3 and the hydroxyl group of the hydroxyl group-containing (meth) acrylate (a3) And the hydroxyl group-containing (meth) acrylate (a3) is about 1: 3.

With respect to the addition reaction of the reaction product with the hydroxyl group-containing (meth) acrylate (a3), the reaction is terminated when the residual isocyanate group content in the reaction system becomes 0.3% by weight or less, whereby urethane (meth) acrylate ) Can be obtained.

In the reaction between the polyester polyol (a1) and the polyisocyanate (a2), or between the reaction product and the hydroxyl group-containing (meth) acrylate (a3), it is also preferable to use a catalyst for promoting the reaction . Examples of such catalysts include dibutyltin dilaurate, dibutyltin diacetate, trimethyltin hydroxide, tetra-n-butyltin, bisacetylacetonato zinc, zirconium tris (acetylacetonate) Zirconium tetraacetylacetonate, and the like, organic metal compounds such as tin octanoate, zinc hexanoate, zinc octenoate, zinc stearate, zirconium 2-ethylhexanoate, cobalt naphthenate, stannous chloride, stannous chloride, Diazabicyclo [2,2,2] octane, 1,8-diazabicyclo [5,4,0] undecene, N, N'-tetramethyluronium, , Amine catalysts such as N, N ', N'-tetramethyl-1, 3-butanediamine, N-methylmorpholine and N-ethylmorpholine, and other catalysts such as bismuth acetate, bismuth bromide, bismuth bismuth, , Dibutylbismuth dilaurate, di Octyl bismuth dilaurate, and organic bismuth compounds such as 2-ethylhexanoate bismuth salt, bismuth naphthenate salt, bismuth isodecanoate salt, bismuth neodecanoate salt, bismuth laurate salt, bismuth maleate salt, bismuth stearate And bismuth-based catalysts such as organic acid bismuth salts such as salts, bismuth oleate salts, bismuth linoleate salts, bismuth acetate salts, bismuth libacyneodecanoate, bismuth disalicylate salts and bismuth salt of dimolyzed bismuth. Butyltin dilaurate, 1,8-diazabicyclo [5,4,0] undecene are very suitable. These may be used singly or in combination of two or more.

In the reaction between the polyester polyol (a1) and the polyisocyanate (a2), and in the reaction of the reaction product with the hydroxyl group-containing (meth) acrylate (a3), an organic compound having no functional group reactive with the isocyanate group Examples of the solvent include organic solvents such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as toluene and xylene and organic solvents such as ethylenically unsaturated monomers , A compound mentioned as the ethylenically unsaturated monomer (B) described later) may be used.

The reaction temperature is usually from 30 to 90 캜, preferably from 40 to 80 캜, and the reaction time is usually from 2 to 10 hours, preferably from 3 to 8 hours.

The urethane (meth) acrylate (A) of the present invention thus obtained has a dielectric constant of 7.0 or less and preferably 6.5 or less, more preferably 6.0 or less, from the viewpoint of suppressing malfunction of the touch panel. The lower limit value of the permittivity is usually 1.0.

If the dielectric constant is too high, the electrostatic capacitance between the electrodes mounted on the touch panel becomes large, which tends to cause malfunction. If the dielectric constant is too low, the capacitance tends to decrease and the detection sensitivity tends to decrease.

The weight average molecular weight of the urethane (meth) acrylate (A) of the present invention is preferably 1,000 to 100,000, particularly preferably 5,000 to 90,000, and more preferably 10,000 to 80,000. When the weight average molecular weight is too small, the adhesive strength tends to decrease. When the weight average molecular weight is too large, the viscosity tends to become too high, and the coating tends to become difficult.

The above-mentioned weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and it was measured by high performance liquid chromatography (Shodex GPC system-11 type, manufactured by Showa Denko K.K.) using a column: Shodex GPC KF-806L Three series of exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical number of steps: 10,000 pieces / filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) .

The viscosity of the urethane (meth) acrylate (A) of the present invention is preferably 1,000 to 1,000,000 mPa · s, more preferably 2,000 to 900,000 mPa · s , More preferably from 3,000 to 800,000 mPa 占 퐏. If the viscosity is too high, handling tends to be difficult. If the viscosity is too low, control of the film after drying tends to be difficult.

The measurement of the viscosity is based on the E-type viscometer.

The active energy ray-curable composition of the present invention contains, in addition to the urethane (meth) acrylate (A), an ethylenically unsaturated monomer (B) (excluding urethane (meth) acrylate desirable.

Examples of the ethylenically unsaturated monomer (B) used in the present invention include monofunctional monomers, bifunctional monomers and monomers having three or more functionalities.

Examples of such monofunctional monomers include styrene monomers such as styrene, vinyl toluene, chlorostyrene, and? -Methyl styrene, methyl (meth) acrylate, ethyl (meth) acrylate, acrylonitrile, Hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- Phenoxyethyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2-hydroxy- (Meth) acrylate, glycerin mono (meth) acrylate, glycidyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl Cyclodecanyl (meth) acrylate, dicyclopentene (Meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (2-methyl- (Meth) acrylate, cyclohexane spiro-2- (1,3-dioxolan-4-yl) (Meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (Meth) acrylate, n-stearyl (meth) acrylate, benzyl (meth) acrylate, phenol ethylene oxide modified (n = 2) (meth) acrylate, isodecyl (Meth) acrylate, nonylphenol propylene oxide modified (n = 2.5) (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, 2- (Meta) acrylate, tetrahydrofurfuryl (meth) acrylate, carbitol (meth) acrylate, benzyl (meth) acrylate and the like, of a phthalic acid derivative such as 2- (Meth) acrylate monomers such as acrylate, butoxyethyl (meth) acrylate, allyl (meth) acrylate, (meth) acryloylmorpholine, polyoxyethylene secondary alkyl ether acrylate, Hydroxyethyl acrylamide, N-methylol (meth) acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, vinyl acetate and the like.

Examples of such bifunctional monomers include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, neopentyl glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, dipropylene glycol di (Meth) acrylates such as modified bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, ethoxylated cyclohexanedimethanol di (Meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, (Meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di Glycidyl ester di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate, and isocyanuric acid ethylene oxide-modified diacrylate.

Examples of such trifunctional or higher functional monomers include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylol propane, glycerin polyglycidyl ether poly (meth) acrylate, isocyanuric acid ethylene oxide Caprolactone-modified pentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, caprolactone-modified pentaerythritol tri (meth) acrylate, caprolactone- Lactone-modified pentaerythritol tetra (meth) acrylate, ethylene oxide-modified dipentaerythritol penta (meth) acrylate, ethylene oxide (Meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, ethoxylated glycerin triacrylate, and the like. .

Also, a Michael adduct of acrylic acid or a 2-acryloyloxyethyl dicarboxylic acid monoester may be used in combination. Examples of the Michael adduct of acrylic acid include acrylic acid dimer, methacrylic acid dimer, acrylic acid trimmer, methacryl Acid trimer, acrylic acid tetramer, and methacrylic acid tetramer.

Examples of the 2-acryloyloxyethyl dicarboxylic acid monoester include carboxylic acid having a specific substituent, such as 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid mono ester, 2 -Acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid monoester, . Other oligomeric ester acrylates may also be mentioned.

The content of the ethylenically unsaturated monomer (B) is preferably 5 to 900 parts by weight, particularly preferably 10 to 600 parts by weight, more preferably 15 to 100 parts by weight based on 100 parts by weight of the urethane (meth) acrylate (A) To 400 parts by weight. When the content is too large, the viscosity tends to be lowered and the adhesive force tends to lower. When the content is too small, the viscosity tends to increase and the coating tends to deteriorate.

In the present invention, it is preferable to further include a photopolymerization initiator (C) in the active energy ray-curable composition, and the photopolymerization initiator (C) is not particularly limited as long as it generates radicals under the action of light. For example, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 4- (2-hydroxyethoxy) phenyl- 2-hydroxy-2-methyl-1-propan-1-one, 2- [4- (2-hydroxyethoxy) 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1- Acetophenones such as 1- [4- (1-methylvinyl) phenyl] propanol oligomer; benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 3,3 ', 4,4'-tetra (t- butylperoxycarbonyl) benzophenone , 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2- propenyloxy) ethyl] 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-diethylthioxanthone, 2,4- Dichloro thioxanthone, 1-chloro-4-propoxyoxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4-dimethyl-9H-thioxanthone- (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis 6-trimethylbenzoyl) -phenylphosphine oxide; and the like. These photopolymerization initiators (C) may be used alone, or two or more of them may be used in combination.

As a preparation of these photopolymerization initiators (C), triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Mihira ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid , 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2-ethylhexyl thioxanthone, 2-ethylhexyl thioxanthone, , 4-diisopropylthioxanthone, and the like can be used in combination. These preparations may be used singly or in combination of two or more.

The content of such a photopolymerization initiator (C) is preferably in the range of from 0.01 to 10 parts by mass, more preferably from 0.1 to 50 parts by mass, more preferably from 0.1 to 50 parts by mass, based on the total amount of the urethane (meth) acrylate (A) (the ethylenically unsaturated monomer (B) B)), it is preferably 1 to 10 parts by weight, particularly preferably 2 to 5 parts by weight. If the content is too small, the curing rate tends to decrease. If too much, the curability does not improve and the economical efficiency tends to be lowered.

The active energy ray curable composition of the present invention may contain an antioxidant, a flame retardant, an antistatic agent, a filler, a labeling agent, a stabilizer, an antioxidant, an antioxidant, It is also possible to blend a reinforcing agent and a quenching agent. Further, as the crosslinking agent, a compound having a function of causing crosslinking by heat, specifically, an epoxy compound, an aziridine compound, a melamine compound, an isocyanate compound, a chelate compound and the like can also be used. As the hydrolysis inhibitor, a carbonylimide compound can also be used.

In order to adjust the viscosity at the time of coating, the active energy ray-curable composition of the present invention may contain an alcohol such as methanol, ethanol, propanol, n-butanol or i-butanol, acetone, methyl isobutyl ketone , Ketones such as methyl ethyl ketone and cyclohexanone, cellosolves such as ethyl cellosolve, aromatic ones such as toluene and xylene, glycol ethers such as propylene glycol monomethyl ether, methyl acetate, ethyl acetate and butyl acetate , A diluting solvent such as acetic acid esters or diacetone alcohol may be used. However, since there is a possibility that the solvent remains in the coating film and the curing component volatilizes at the time of drying, it is preferable that the solvent contains substantially no solvent.

The term "substantially solvent-free" means that the active energy ray-curable composition is generally not more than 1% by weight, preferably not more than 0.5% by weight, more preferably not more than 0.1% by weight.

The active energy ray curable composition of the present invention can be used as a coating composition for various base films or as a pressure sensitive adhesive composition such as an adhesive for various members or a surface protective sheet. Do.

In addition, the active energy ray-curable pressure-sensitive adhesive composition of the present invention may contain a tackifier such as a polythiol compound from the viewpoints of suppression of unreacted components and improvement of adhesive force.

The polythiol compound is preferably a compound having 2 to 6 mercapto groups in the molecule, and examples thereof include aliphatic polythiols such as alkanethiol having about 2 to 20 carbon atoms, aromatic polythiols such as xylene dithiol, Polythiols obtained by substituting halogen atoms of halohydrin adducts of alcohols with mercapto groups, polythiols composed of hydrogen sulfide reaction products of polyepoxide compounds, polyhydric alcohols having 2 to 6 hydroxyl groups in the molecule and thioglycol And polythiols composed of an acid,? -Mercaptopropionic acid, or an esterified product of? -Mercaptobutanoic acid and the like, and one kind or two kinds or more of them can be used.

When the polythiol compound is contained, the content of the urethane (meth) acrylate (A) and the ethylenically unsaturated (meth) acrylate (A) Is preferably 10 parts by weight or less, particularly preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the total amount of the monomer (B).

The active energy ray-curable pressure-sensitive adhesive composition of the present invention is preferably a cured pressure-sensitive adhesive. Specifically, it is usually applied to a base sheet or the like to be provided for practical use as an adhesive sheet or the like, and after being applied to a base sheet or the like, it is crosslinked by irradiation with active energy rays to become a pressure-sensitive adhesive, thereby exhibiting adhesiveness.

The pressure-sensitive adhesive sheet is also meant to include an adhesive film and a pressure-sensitive adhesive tape when no particular mention is made, and is characterized in that a pressure-sensitive adhesive obtained by curing the active energy ray-curable pressure-sensitive adhesive composition of the present invention is laminated.

Further, in the present invention, the separator can be laminated on the surface of the pressure-sensitive adhesive for the purpose of protecting the pressure-sensitive adhesive from contamination until the pressure-sensitive adhesive sheet is attached to the adherend (member).

Examples of the base sheet include a polyester resin such as polyethylene terephthalate and polybutylene terephthalate; a polyolefin resin such as polyethylene, polypyrrole filament and ethylene-propylene copolymer; a polycarbonate resin; a polyurethane resin; A resin sheet such as an acrylic resin, a polystyrene resin, an ethylene-vinyl acetate copolymer, a polyvinyl chloride, a polybutene, a polyester, a polymethylpentene and an acrylonitrile butadiene styrene copolymer (ABS) Various substrate sheets may be subjected to surface treatment such as anchor layer, corona treatment or plasma treatment.

As the separator, a resin sheet exemplified above as the substrate sheet or a substrate such as paper, cloth, nonwoven fabric or the like can be used.

For forming the pressure-sensitive adhesive layer on the base sheet, a direct coating method in which the active energy ray-curable pressure-sensitive adhesive composition is directly coated on the base sheet, a transfer coating method in which the active energy ray- .

The active energy ray-curable pressure-sensitive adhesive composition is usually coated with a solvent, if necessary, after being adjusted to a suitable viscosity for coating. The method of applying the active energy ray-curable pressure-sensitive adhesive composition to the base sheet or the separator is not particularly limited and examples thereof include a spraying method, a shower method, a dipping method, a roll method, a spin method, a curtain method, a flow method, a slit method, A wet coating method such as printing, inkjet printing, and printing with a dispenser.

When the applied active energy ray-curable composition contains a solvent, it is dried after coating. As drying conditions, a drying temperature and a drying time sufficient to volatilize the solvent in the coated active energy ray-curable composition may be set. The drying temperature is usually 40 to 100 占 폚, preferably 50 to 90 占 폚, and the drying time is preferably 1 to 60 minutes from the viewpoint of production suitability.

Further, in the case where the active energy ray-curable pressure-sensitive adhesive composition is a solid or a high-viscosity liquid, the viscosity is not adjusted with a solvent but the active energy ray curable composition is heated to lower It is possible.

The active energy ray-curable pressure-sensitive adhesive composition of the present invention is coated on a substrate sheet, dried, and crosslinked by irradiation with an active energy ray to form a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

In the direct coating method, the active energy ray-curable pressure-sensitive adhesive composition may be coated on the substrate sheet and heated and dried. Thereafter, the active energy ray may be irradiated and then the separator may be attached. The radiation-curable pressure-sensitive adhesive composition may be applied, heated and dried, and then the separator may be attached and irradiated with active energy rays. On the other hand, in the transfer coating method, the separator may be coated with an active energy ray-curable pressure-sensitive adhesive composition, heated and dried, then irradiated with an active energy ray, and then the base sheet may be bonded to the separator. After heating and drying, the substrate sheet may be pasted thereon and then the active energy ray may be irradiated.

As the above-mentioned active energy ray, it is possible to use not only electromagnetic waves such as far-ultraviolet ray, ultraviolet ray, near-ultraviolet ray and infrared ray, electromagnetic waves such as X-ray and gamma ray but also electron ray, proton ray and neutron ray. , It is advantageous to cure by ultraviolet ray irradiation from the price and the like. In addition, when electron beam irradiation is performed, curing can be performed without using a photopolymerization initiator (C).

As a method of curing by ultraviolet irradiation, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, an LED lamp, or the like is used as a high-pressure mercury lamp, a super high pressure mercury lamp, a carbon arc lamp, etc. emitting light in a wavelength range of 150 to 450 nm 30 to 5,000 mJ / cm 2.

After irradiation with ultraviolet rays, heating may be carried out as necessary to achieve complete curing.

The thickness of the pressure-sensitive adhesive layer formed on the substrate sheet after irradiation with active energy rays is appropriately set according to the application, but is usually 5 to 300 占 퐉, preferably 10 to 250 占 퐉. If the thickness of the pressure-sensitive adhesive layer is too thin, the pressure-sensitive adhesive property tends to be unstable. If the pressure-sensitive adhesive layer is too thick, a residual paste tends to be easily formed.

The pressure-sensitive adhesive of the present invention thus obtained is preferably 6.5 or less, more preferably 6.0 or less from the viewpoint of permittivity of 7.0 or less and suppression of malfunction of the touch panel. The lower limit value of the permittivity is usually 1.0.

If the dielectric constant is too high, the capacitance between the electrodes mounted on the touch panel tends to become large, which tends to cause malfunction. If the dielectric constant is too low, the capacitance tends to decrease and the detection sensitivity tends to decrease.

The adhesive force of the pressure-sensitive adhesive sheet of the present invention is usually 0.1 to 100 N / 25 mm, more preferably 0.5 to 75 N / 25 mm, further preferably 1 to 50 N / 25 mm, particularly preferably 10 to 50 N / 25 mm, particularly preferably 17.5 to 50 N / 25 mm.

Since the urethane (meth) acrylate of the present invention has a low dielectric constant, the active energy ray-curable composition of the present invention containing the same has a low dielectric constant, and the active energy ray-curable pressure- Is useful as an adhesive for an optical member such as an optical device such as a touch panel or an optical recording medium and is particularly suitably used for attaching a touch panel structural member or for an organic EL display bag.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In the examples, " part " and "% "

≪ Example 1 >

[Synthesis of urethane acrylate (A-1)]

(0.057 mol) of isophorone diisocyanate, a bifunctional polyesterpolyol (hydroxyl value of 60.3 mgKOH / g, number average molecular weight of 2,000, repetitive structure (number average molecular weight: 2,000), and the like) was added to a four-necked flask equipped with a thermometer, a stirrer, , 84.7 g (0.046 mol) of dibasic tin dilaurate as a reaction catalyst, and the reaction was carried out at 80 ° C for 6 hours. Then, 2.7 g (0.023 mol) of 2-hydroxyethyl acrylate and 0.04 g of 2,6-di-tert-butylcresol as a polymerization inhibitor were added and reacted at 60 DEG C for 3 hours, The reaction was terminated to obtain urethane acrylate (A-1) (weight average molecular weight (Mw): 30,000).

The obtained urethane acrylate (A-1) was evaluated in the following manner.

<Permittivity>

43 parts by weight of ethyl acetate and 4 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Co., Ltd., "IRGACURE 184") as a photopolymerization initiator were added to 100 parts by weight of urethane acrylate (A- And uniformly mixed to obtain an active energy ray curable composition.

(Preparation of test piece for dielectric constant measurement)

The active energy ray curable composition obtained above was applied onto an untreated polyethylene terephthalate (PET) film (thickness 50 탆) so as to have a film thickness after curing of 150 탆 by using an applicator and placed in a drier at 60 캜 for 10 minutes, The active energy ray curable composition side was laminated from the top with an untreated polyethylene terephthalate (PET) film (thickness 50 탆), and the laminate was irradiated with light from a table UV irradiator ("Conveyor-type table irradiator" ) Under a condition of 80 W / cm (high-pressure mercury lamp) × 18 cm H × 2.04 m / min × 3 Pass (cumulative irradiation dose: 2,400 mJ / cm 2), the cured film was irradiated with ultraviolet rays from the laminate side, .

(How to measure)

A test piece obtained using an HP4284A PASSIJON LCR meter (manufactured by Agilent) was sandwiched between electrodes and an electric field was applied at a frequency of 1 MHz to measure the electric capacity. From the change in capacitance between the electrodes, the permittivity of the active energy ray- Were calculated and evaluated as follows. In addition, the permittivity of the active energy ray-curable pressure-sensitive adhesive composition can be regarded as the permittivity of the urethane (meth) acrylate contained in the active energy ray-curable pressure-sensitive adhesive composition.

(Evaluation standard)

○: not more than 7.0

X is greater than 7.0

<Compatibility>

The urethane acrylate (A-1) and the following ethylenically unsaturated monomers were mixed so as to have a weight ratio of 1: 1 and mixed well. The appearance of the mixture was observed and evaluated as follows.

(B-1) Aliphatic monomer: butyl acrylate

(B-2) aromatic monomer: phenoxyethyl acrylate

(B-3) Hydroxyl group-containing monomer: 4-hydroxybutyl acrylate

(Evaluation standard)

○: The liquid mixture was uniform.

X: The liquid mixture was uneven.

Then, the adhesive property was evaluated for an active energy ray-curable pressure-sensitive adhesive composition containing urethane acrylate (A-1).

<Adhesion>

81 parts of phenoxyethyl acrylate as the ethylenically unsaturated monomer (B) and 1 part of 1-hydroxy-cyclohexyl-phenyl-ketone (BASF Japan Co., Ltd.) as a photopolymerization initiator were added to 100 parts of the urethane (meth) IRGACURE 184 &quot;) were uniformly mixed to obtain an active energy ray-curable pressure-sensitive adhesive composition.

(Production of pressure-sensitive adhesive sheet for adhesion measurement)

The obtained active energy ray-curable pressure-sensitive adhesive composition was applied to a back-tacky polyethylene terephthalate (PET) film (thickness: 125 탆) using an applicator so that the film thickness after curing became 175 탆, (High-pressure mercury lamp) x 18 cmH x 2.04 m / min x 3 Pass (cumulative dose: 2,400 mJ / cm 2) in a "conveyor-type tabletop irradiation device" .

(Test Methods)

The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm x 100 mm, and then pressed on the glass plate as an adherend for 2 reciprocations using an 2 kg rubber roller under an atmosphere of 23 deg. C and a relative humidity of 50%. The test piece was allowed to stand in the same atmosphere for 30 minutes and subjected to a 180 degree peel test at a peel rate of 0.3 m / min to measure the adhesive strength (N / 25 mm).

(Evaluation standard)

O: 17.5 N / 25 mm or more

DELTA: 10 N / 25 mm or more, and 17.5 N / 25 mm or less

X: less than 10 N / 25 mm

&Lt; Example 2 &gt;

[Synthesis of urethane acrylate (A-2)]

(0.054 mol) of isophorone diisocyanate, a bifunctional polyesterpolyol (hydroxyl value: 56.0 mgKOH / g, number average molecular weight: 2,000, number average molecular weight: 2,000, number average molecular weight: 85.6 g (0.043 mol) of dibasic tin dilaurate as a reaction catalyst was added thereto, and the mixture was reacted at 80 ° C for 6 hours 2.5 g (0.022 mol) of 2-hydroxyethyl acrylate and 0.04 g of 2,6-di-tert-butylcresol as a polymerization inhibitor were placed and reacted at 60 DEG C for 3 hours to obtain a residual isocyanate group of 0.3% The reaction was terminated at the time point to obtain urethane acrylate (A-2) (weight average molecular weight (Mw): 38,000).

The urethane acrylate (A-2) thus obtained was evaluated for dielectric properties and compatibility in the same manner as in Example 1. The adhesive property of the active energy ray-curable pressure-sensitive adhesive composition containing urethane acrylate (A-2) was also evaluated in the same manner as in Example 1.

&Lt; Comparative Example 1 &

[Synthesis of urethane acrylate (A'-1)]

(0.053 mol) of isophorone diisocyanate, a bifunctional polyester polyol (hydroxyl value of 55.4 mg KOH / g, number average molecular weight of 2,000, and repeating structure 85.7 g (0.042 mol) of dibasic tin dilaurate as a reaction catalyst was added, and the mixture was reacted at 80 DEG C for 6 hours 2.5 g (0.022 mol) of 2-hydroxyethyl acrylate and 0.04 g of 2,6-di-tert-butylcresol as a polymerization inhibitor were placed and reacted at 60 DEG C for 3 hours to obtain a residual isocyanate group of 0.3% The reaction was terminated at the time point to obtain urethane acrylate (A'-1) (weight average molecular weight (Mw): 26,000).

The obtained urethane acrylate (A'-1) was evaluated for dielectric constant and compatibility in the same manner as in Example 1. The tackiness of the active energy ray-curable pressure-sensitive adhesive composition containing urethane acrylate (A'-1) was evaluated in the same manner as in Example 1.

&Lt; Comparative Example 2 &

[Synthesis of urethane acrylate (A'-2)]

(0.045 mole), bifunctional hydrogenated polybutadiene polyol (hydroxyl value of 48.3 mg KOH / g, number average molecular weight of 2,000) 87.7 (number average molecular weight of 2,000) was added to a four-necked flask equipped with a stirrer, a thermometer, a stirrer, and 0.02 g of dibutyltin dilaurate as a reaction catalyst were placed and reacted at 80 DEG C for 6 hours. Then, 2.2 g (0.015 mol) of 4-hydroxybutyl acrylate and 2.6 g (A'-2) (weight average molecular weight (Mw): 49,000 (weight-average molecular weight (Mw)) was added at the time when the remaining isocyanate group became 0.3% ).

The obtained urethane acrylate (A'-2) was evaluated for dielectric constant and compatibility in the same manner as in Example 1.

Subsequently, 69 parts by weight of isodecyl acrylate as an ethylenically unsaturated monomer (B), 1 part by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (BASF Japan Co., Ltd.) as a photopolymerization initiator, 6.8 parts of "IRGACURE 184" manufactured by Kabushiki Kaisha) were uniformly mixed to obtain an active energy ray-curable pressure-sensitive adhesive composition, and the adhesiveness was evaluated in the same manner as in Example 1.

The evaluation results are shown in Table 1 below.

From the above evaluation results, it can be seen that the urethane acrylates of Examples 1 and 2 having a dielectric constant of 7.0 or less have a good appearance of the blend with various ethylenically unsaturated monomers and excellent compatibility. It is also understood that the active energy ray-curable pressure-sensitive adhesive compositions of Examples 1 and 2 containing urethane acrylate exhibit excellent adhesiveness.

On the other hand, the urethane (meth) acrylate of Comparative Example 1 having a dielectric constant of more than 7.0 is excellent in compatibility but has a high dielectric constant and is difficult to apply to an adhesive for an optical member

The urethane acrylate of Comparative Example 2 in which the polybutadiene-based polyol was reacted in place of the polyester-based polyol had a dielectric constant of 7.0 or less. However, the urethane acrylate is less compatible with the urethane acrylate than the examples.

Although the present invention has been described in detail with reference to specific embodiments, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. The present application is based on Japanese Patent Application No. 2014-233837 filed on November 18, 2014, the contents of which are incorporated herein by reference.

Since the active energy ray-curable composition of the present invention has a low dielectric constant, the active energy ray-curable pressure-sensitive adhesive composition and pressure-sensitive adhesive of the present invention containing the same can be used as an adhesive for optical members such as optical devices such as touch panels and optical recording media And is particularly suitably used for attaching a touch panel structural member or for an organic EL display bag.

Claims (10)

(Meth) acrylate (A) which is a reaction product of a polyester polyol (a1), a polyisocyanate (a2) and a hydroxyl group-containing (meth) acrylate (a3) ) Is not more than 7.0. The method according to claim 1,
Wherein the content ratio X of oxygen atoms in the repeating structural units of the polyester-based polyol (a1) is 0.35 or less.
However, the content X is a value represented by the following formula (1).
(1) X = 16c / (12a + b + 16c)
a: the number of carbon atoms in the repeating structural unit of the polyester-based polyol (a1)
b: the number of hydrogen atoms in the repeating structural units of the polyester-based polyol (a1)
c: the number of oxygen atoms in the repeating structural unit of the polyester-based polyol (a1) The method according to claim 1 or 2,
The polyester-based polyol (a1) is a polycondensation product of a polyvalent carboxylic acid component containing a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms and a polyhydric alcohol component. 4. The method according to any one of claims 1 to 3,
The number-average molecular weight of the polyester-based polyol (a1) is 500 to 12,000. 5. The method according to any one of claims 1 to 4,
Wherein the urethane (meth) acrylate (A) has a weight average molecular weight of 1,000 to 100,000. 6. The method according to any one of claims 1 to 5,
And an ethylenically unsaturated monomer (B) (excluding the above urethane (meth) acrylate (A)). An active energy ray-curable pressure-sensitive adhesive composition containing the active energy ray-curable composition according to any one of claims 1 to 6. A pressure-sensitive adhesive in which the active energy ray-curable pressure-sensitive adhesive composition according to claim 7 is cured. A pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive according to claim 8 is laminated on a base sheet. (A1), a polyisocyanate (a2) and a hydroxyl group-containing (meth) acrylate (a3), which are polycondensates of a polyvalent carboxylic acid component and a polyhydric alcohol component containing a polyvalent carboxylic acid having an alkylene group having 5 to 20 carbon atoms, ) Urethane (meth) acrylate.