KR20150021880A - Optical adhesive composition, optical adhesive sheet, imaging display device, and input and output apparatus - Google Patents

Abstract

The present invention has the subject of providing an optical adhesive composition which can provide an adhesive layer having excellent adhesion while having low permittivity, an optical adhesive sheet obtained by using the optical adhesive composition, and an imaging display device including the optical adhesive sheet, and an input and output apparatus. The optical adhesive composition as a means for solving the subject contains a copolymer (A) of a monomer mixture (here, component (a1) and component (a2) are 45 wt% or more and 100 wt% or less in total) containing (a1) 3 wt% or more and 39 wt% or less of methacrylic acid alkyl ester monomer having an alkyl group of 10 or more and 18 or less carbon atoms; and (a2) 20 wt% or more and 97 wt% or less of a methacarylic acid alkyl ester monomer having an alkyl group of one or more and nine or less carbon atoms.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical pressure-sensitive adhesive composition, an optical pressure-sensitive adhesive sheet, an image display device, and an input / output device,

The present invention relates to an optical pressure-sensitive adhesive composition, an optical pressure-sensitive adhesive sheet, an image display device, and an input / output device.

2. Description of the Related Art Recently, an image display apparatus such as a liquid crystal display apparatus and an input / output apparatus such as a touch panel used in combination with an image display apparatus are widely used. In the production of these image display apparatuses and input / output apparatuses, a pressure-sensitive adhesive composition is used for bonding structural members.

As a result of the miniaturization of electronic parts constituting these image display devices and input / output devices, there is a problem in that, for example, due to the high frequency noise generated in the circuit or the charge of the dielectric material sandwiched by the conductive material at the time of driving, Malfunction due to noise can not be ignored. In particular, the pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive as a main component has a relatively high relative dielectric constant, and when the pressure-sensitive adhesive composition having such a high specific dielectric constant is used, the capacitance as an insulating layer is high and malfunctions due to high- have.

For example, Patent Document 1 discloses an optical spot-on sheet for the purpose of preventing a malfunction of a capacitive touch-panel type input / output device.

WO 2010147047 A

The present invention relates to an optical pressure-sensitive adhesive composition for optical use which can obtain a pressure-sensitive adhesive layer having a low dielectric constant and an excellent adhesive force, an optical pressure-sensitive adhesive sheet obtained by using the optical pressure-sensitive adhesive composition, and an image display apparatus and input / Lt; / RTI >

The present inventors have found that (a1) a copolymer of a monomer mixture containing a methacrylic acid alkyl ester having an alkyl group of 10 to 18 carbon atoms, by adjusting the content of the methacrylic acid ester, It has been found that it is possible to obtain a pressure-sensitive adhesive sheet having a low dielectric constant and an excellent adhesive force by using a composition containing the copolymer.

(A1) 3 mass% or more and 39 mass% or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 or more and 18 or less carbon atoms, (a2) 1 to 9 carbon atoms (A1) and the component (a2) is not less than 45% by mass and not more than 100% by mass based on 100% by mass of the monomer mixture comprising the methacrylic acid alkyl ester monomer ) Of a copolymer (A).

2. The pressure-sensitive adhesive composition for optical use according to the above 1, wherein the copolymer (A) has a weight average molecular weight of 50,000 or more and 700,000 or less.

3. The pressure-sensitive adhesive composition for optical use according to 1 or 2 above, wherein the copolymer (A) has a glass transition temperature (Tg) of 0 ° C or lower.

4. The optical pressure-sensitive adhesive composition for optical use according to any one of 1 to 3 above, wherein the content of the component (a2) relative to the content of the component (a1) in the monomer mixture may be 0.5 or more and 5 or less .

5. The pressure-sensitive adhesive composition for optical use according to any one of 1 to 4 above, further comprising (a3) 2% by mass or more and 30% by mass or less of a hydroxyl group-containing monomer.

6. The pressure-sensitive adhesive composition for optical use according to the above-mentioned 5, wherein the (a3) hydroxyl group-containing monomer may be a methacrylic acid alkyl ester monomer containing a hydroxyl group.

7. The optical pressure-sensitive adhesive composition for optical use according to any one of the above 1 to 6, wherein the monomer mixture further comprises (a4) 0.1 mass% or more and 5 mass% or less of nitrogen atom-containing monomer.

8. The pressure-sensitive adhesive composition for optical use according to any one of the above 1 to 7, wherein the total amount of the methacrylic acid ester monomers in the monomer mixture is 80% by mass or more and 100% by mass or less.

9. The optical pressure-sensitive adhesive composition for optical use according to any one of the above 1 to 8, wherein the content of the copolymer (A) in the pressure-sensitive adhesive composition is 70% by mass or more and 99.9% by mass or less.

10. The optical pressure-sensitive adhesive composition for optical use according to any one of claims 1 to 9, wherein the hydroxyl value of the copolymer (A) is 15 or more and 150 or less.

11. The optical pressure-sensitive adhesive composition for optical use according to any one of the items 1 to 10, wherein the gel fraction of the (A) copolymer is 30% or more and 90% or less.

12. The optical pressure-sensitive adhesive composition for optical use according to any one of items 1 to 11, wherein the copolymer (A) has a crosslinkable functional group, and (B) a crosslinking agent.

13. The pressure-sensitive adhesive composition for optical use according to the above-mentioned 12, wherein the pressure-sensitive adhesive composition (B) comprises 0.01 to 20 parts by mass of the crosslinking agent (B) relative to 100 parts by mass of the copolymer (A).

14. The pressure-sensitive adhesive composition for optical use according to 12 or 13, wherein the crosslinking agent (B) is an isocyanate crosslinking agent.

15. The optical pressure-sensitive adhesive composition for optical use according to any one of the above 1 to 14, which can be used for joining members constituting a touch panel type input / output device or an image display device.

16. The optical pressure-sensitive adhesive sheet according to one aspect of the present invention may comprise a pressure-sensitive adhesive layer formed from the optical pressure-sensitive adhesive composition according to any one of the above-mentioned 1 to 15.

17. The optical pressure sensitive adhesive sheet for optical use according to item 16 above, wherein the relative dielectric constant at 100 Hz is 4.0 or less.

18. An image display apparatus according to one aspect of the present invention includes the optical adhesive sheet described in the above item 16 or 17. [

19. The input / output device according to one aspect of the present invention includes the optical adhesive sheet described in the above 16 or 17.

(A1) 3 mass% or more and 39 mass% or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms, (a2) a methacrylic acid having an alkyl group of 1 to 9 carbon atoms Wherein the sum of the component (a1) and the component (a2) is 45 mass% or more and 100 mass% or less, wherein the total amount of the alkylester monomer is 20 mass% or more and 97 mass% A pressure-sensitive adhesive layer having a low dielectric constant and an excellent adhesive force can be obtained by using the optical pressure-sensitive adhesive composition. Further, the pressure-sensitive adhesive layer has excellent durability and is excellent in transparency, so that it can be suitably used, for example, in an image display apparatus and an input / output apparatus.

1 is a cross-sectional view schematically showing a configuration of a first input / output device (touch panel type input / output device) according to an embodiment of the present invention;
2 is a cross-sectional view schematically showing a configuration of a second input / output device (touch panel type input / output device) according to an embodiment of the present invention;
3 is a cross-sectional view schematically showing a configuration of a known input / output device (touch panel type input / output device).

Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, unless otherwise stated otherwise, "part" means "part by mass" and "%" means "% by mass".

1.1. Pressure-sensitive adhesive composition for optical

1.1. (A) Copolymer

(A1) a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms (hereinafter, simply referred to as " component (a1) ") in the present specification (A2) a methacrylic acid alkyl ester monomer having an alkyl group having 1 to 9 carbon atoms (hereinafter sometimes simply referred to as " component (a2) ")) (A) a copolymer comprising 20 mass% or more and 97 mass% or less, wherein the sum of the component (a1) and the component (a2) is 45 mass% or more and 100 mass% Quot; component (A) " in some cases).

From the viewpoint of enhancing the anti-wet heat resistance, the component (A) preferably has a functional group. In the present invention, the anti-wet heat whitening property is a phenomenon that the adhesive film is whitened (clouded) when it is returned to room temperature after exposure to high temperature and high humidity conditions (for example, 60 ° C and 95% RH). The functional group is a crosslinkable functional group capable of reacting with a crosslinking agent (B) to form a crosslinking structure described later, and examples thereof include a hydroxyl group and an amino group.

Further, the component (A) is preferably substantially free of a carboxyl group. In the present invention, "the component (A) substantially contains no carboxyl group" means, for example, that the content of the carboxyl group-containing monomer in the monomer mixture is 0.1% by mass or less, and more specifically, , It is referred to as not using a carboxyl group-containing monomer as a monomer constituting the monomer mixture.

1.1.1. Monomer mixture

In order to obtain a pressure-sensitive adhesive layer excellent in adhesion to an adherend (in particular, glass), low in dielectric constant, and excellent in durability, the component (A) (A1), a component (a2), a component (a3) and a component (a4), and more preferably a methacrylic polymer.

In the present invention, the "methacrylic polymer" refers to a polymer containing at least one selected from methacrylic acid, methacrylic acid salt and methacrylic acid ester in an amount of 50 mass% or more in the constitutional unit.

Further, in the present invention, the term "methacrylic acid ester monomer" is a concept including a methacrylic acid ester monomer having a functional group (for example, hydroxyl group, amino group, etc.) in addition to the methacrylic acid alkyl ester monomer. Thus, for example, the "methacrylic acid alkyl ester monomer" includes a hydroxyl group-containing methacrylic acid ester monomer used as the component (a1) and component (a2) described later and component (a3) described later.

1.1.1-1. (a1) Component

The component (a1) can contribute to adjust the Tg of the component (A) to 0 캜 or lower.

When the component (a1) exceeds 39 mass% of the monomer mixture, the adhesive force of the pressure-sensitive adhesive layer obtained using the optical pressure-sensitive adhesive composition according to the present embodiment to the adherend is lowered and sufficient reliability may not be obtained. On the other hand, If it is less than 3% by mass, the glass transition temperature (Tg) of the component (A) may become high and the pressure-sensitive adhesive layer may become excessively hard. The content of the component (a1) in the monomer mixture is preferably 3% by mass or more and 39% by mass or less, more preferably 10% by mass or more and 39% by mass or less in terms of excellent durability and suitable hardness , And more preferably 20 mass% or more and 39 mass% or less.

The component (a1) may be, for example, a linear alkyl group, a branched chain alkyl group or a methacrylic acid alkyl ester monomer having a cyclic alkyl group, and among them (particularly) the Tg of the component (A) It is preferably a linear or branched alkyl group from the viewpoint of imparting flexibility to the pressure-sensitive adhesive layer obtained from the mixture. Among them, the alkyl group contained in the component (a1) is preferably a methacrylic acid alkyl ester monomer having a linear alkyl group having 10 to 16 carbon atoms.

More specifically, the component (a1) may include, for example, n-decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, n-hexadecyl methacrylate, And alkyl methacrylate monomers having a linear alkyl group such as aryl. One of these monomers may be used alone or two or more of them may be used in combination.

1.1.1-2. (a2) Component

The component (a2) can contribute to the adhesive strength and durability of the pressure-sensitive adhesive layer obtained using the optical pressure-sensitive adhesive composition according to the present embodiment.

If the content of the component (a2) exceeds 97 mass% of the monomer mixture, the pressure-sensitive adhesive layer obtained using the optical pressure-sensitive adhesive composition according to the present embodiment is excessively hardened and sufficient adhesion to the adherend can not be obtained. , The durability may be poor. The content of the component (a2) in the monomer mixture is preferably 30% by mass or more and 86.8% by mass or less, more preferably 30% by mass or more and 74.7% by mass or less in view of better durability and more suitable hardness More preferable.

The component (a2) may be, for example, a linear alkyl group or a methacrylic acid alkyl ester monomer having a branched chain alkyl group. Among them, the Tg of the component (A) and the tackiness of the resulting pressure- , And a linear or branched alkyl group having 5 to 9 carbon atoms.

More specifically, the component (a2) may be at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, Methacrylic acid alkyl ester monomers having a linear alkyl group such as n-nonyl acrylate;

Methacrylic acid alkyl ester monomers having a branched chain alkyl group such as isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, and 2-ethylhexyl methacrylate. And one of these may be used alone or in combination of two or more.

The content of the component (a2) relative to the content of the component (a1) is preferably from 0.5 to 5, more preferably from 0.8 to 3, from the viewpoint that the Tg of the copolymer can be adjusted to 0 캜 or lower in the monomer mixture desirable. From the same viewpoint, the total amount of the component (a1) and the component (a2) is usually 45 mass% or more and 100 mass% or less, preferably 60 mass% or more and 98 mass% or less.

1.1.1-3. (a3) Component

From the viewpoint of enhancing the whitening resistance of the pressure-sensitive adhesive layer obtained by using the pressure-sensitive adhesive composition for optical use according to the present embodiment, the above-mentioned monomer mixture contains 2% by mass or more of (a3) a hydroxyl group-containing monomer (simply referred to as " component (a3) 30% by mass or less.

The component (a3) is a component capable of establishing a crosslinking structure with the crosslinking agent (B) described later. When the content of the component (a3) exceeds 30% by mass of the monomer mixture, the relative dielectric constant of the pressure-sensitive adhesive layer may be excessively high, while if it is less than 2% by mass, the pressure- The content of the component (a3) in the monomer mixture is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or less, and more preferably 5% by mass or less, in view of better whitening resistance of the pressure- And more preferably not less than 15% by mass.

As the component (a3), for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy- Acrylate alkyl ester monomers such as 2-hydroxy-3-phenoxypropyl; Acrylic acid alkylene glycols such as ethylene glycol acrylate, polyethylene glycol acrylate, propylene glycol acrylate, and polypropylene glycol acrylate; 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-chloropropyl methacrylate, Methacrylic acid alkyl ester monomers such as 2-hydroxy-3-phenoxypropyl acrylate and 2-hydroxy-3-phenoxypropyl methacrylate, ethylene glycol methacrylate, polyethylene glycol methacrylate, And methacrylic acid alkylene glycol such as propylene glycol. One of these may be used singly or two or more of these may be used in combination. Among them, from the viewpoint of excellent compatibility with the component (a1) and the component (a2), the component (a3) is preferably a methacrylic acid ester monomer containing a hydroxyl group.

1.1.1-4. (a4) Component

From the viewpoint of imparting cohesive force to the pressure-sensitive adhesive composition for optical use according to the present embodiment, the monomer mixture contains 0.1% by mass or more and 5% by mass or less of (a4) a nitrogen atom-containing monomer . the nitrogen atom contained in the component (a4) binds to hydrogen atoms present in the pressure-sensitive adhesive composition, and the hydrogen atom participates in the formation of hydrogen bonds in the pressure-sensitive adhesive composition, so that a high cohesive force can be exhibited. The content of the component (a4) in the monomer composition is preferably 0.2 mass% or more and 4 mass% or less, and more preferably 0.3 mass% or more and 3 mass% or less, from the viewpoint of exhibiting a higher cohesive force.

The component (a4) is preferably, for example, an amide group or an amino group-containing monomer. The component (a4) is an amide group or an amino group-containing monomer, thereby accelerating the reaction between the component (A) and the component (B) described later, and further, the hydrogen atom bonding to the nitrogen atom constituting the amide group or amino group, By participating in the formation of hydrogen bonds in the pressure-sensitive adhesive composition, a higher cohesive force can be exhibited. When the component (a4) is a cyclic nitrogen atom-containing monomer, the content of the cyclic nitrogen atom-containing monomer is preferably 0.5% by mass or less (for example, 0% by mass or more and less than 0.5% by mass) , And is preferably less than 0.1 mass% (for example, 0 mass% or more and less than 0.1 mass%).

Examples of the component (a4) include amino group-containing monomers such as N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, .

Examples of the amide group-containing monomer include N, N-dimethylaminopropylacrylamide, N, N'-dimethyl acrylamide, N, N'-diethylacrylamide, N, (Meth) acrylamide, N, N'-dimethylaminopropylacrylamide, N-isopropylacrylamide, tert-octyl (meth) acrylamide, diacetone acrylamide, ) Acrylamide, and (meth) acrylamide.

Examples of the nitrogen-containing heterocyclic ring-containing monomer include pentamethylpiperid (meth) acrylate, vinylpyridine, vinylpyrrolidone, acryloylpolyamine and vinylcaprolactam.

Of these, one type may be used alone, or two or more types may be used in combination.

From the viewpoint of compatibility with the component (a1), the component (a2) and the component (a3), the monomer (a4) is preferably a monomer having a (meth) acryloyl group.

In the pressure-sensitive adhesive composition for optical use according to the present embodiment, the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive composition for optical use has a low specific dielectric constant, excellent durability, and good adhesion to an adherend (particularly, glass) (A1), (a2), (a3) and (a4) in the monomer mixture for obtaining the component (A) may be 80 mass% or more and 100 mass% Or more and 100 mass% or less.

From the standpoint of achieving a low relative dielectric constant, excellent adhesive strength, and durability in the optical pressure-sensitive adhesive composition for an optical device according to the present embodiment and further reducing the relative dielectric constant, the methacrylic acid ester monomer Is preferably 80 mass% or more and 100 mass% or less, more preferably 85 mass% or more and 99.9 mass% or less, and further preferably 90 mass% or more and 99.9 mass% or less.

For example, in the optical pressure-sensitive adhesive composition for an optical element according to the present embodiment, from the viewpoint of further reducing the dielectric constant and achieving more excellent durability, the component (a1), the component (a1), the component (a2) and the component (a3) are both 79.9 mass% or more and 99 mass% or less, and the total amount of the component .

1.1.1-5. (a5) Component

The monomer mixture may contain a copolymerizable monomer other than the component (a1), the component (a2), the component (a3) and the component (a4), which are components (a5). Examples of the component (a5) include acrylic acid alkyl ester monomers having an alkyl group of 1 to 18 carbon atoms, carboxyethyl acrylate, benzyl (meth) acrylate, 2-naphthyl acrylate, phenoxyethyl acrylate (Meth) acrylic acid ester monomers having an aromatic ring; (Meta) acrylate, styrene,? -Methylstyrene, o-methylstyrene having an ether group such as dicyclopentenyloxyethyl acrylate, glycidyl (meth) acrylate and tetrahydrofurfuryl methacrylate, Styrene monomers such as p-methylstyrene, and the like; Carboxylic acid vinyl esters such as vinyl acetate; Vinyl (meth) acryloyl group-containing macromonomers, and the like. These may be used alone or in combination of two or more. The content of the component (a5) in the monomer composition is preferably 0 mass% or more and 20 mass% or less, more preferably 0 mass% or more and 10 mass% or less.

1.1.2. Tg

The optical pressure-sensitive adhesive composition for an optical device according to the present embodiment is excellent in step-following property of the pressure-sensitive adhesive layer obtained by using the optical pressure-sensitive adhesive composition for the optical part, and also has excellent durability and adhesiveness with the adherend layer , The Tg of the component (A) is preferably 0 DEG C or lower, more preferably -40 DEG C or higher and -10 DEG C or lower. In the present invention, the Tg of the component (A) is a value calculated by the following formula (1) (formula of Fox (FOX)).

1 / Tg _A = W _a1 / Tg _a1 + W _a2 / Tg _a2 + W _a3 / Tg _a3 + W _a4 / Tg _a4 + W _a5 / Tg _a5

(In the formula, Tg _A is, (A) component of the glass transition represents a temperature (K), Tg _a1, Tg _a2, Tg _a3 is the (a1) component, each constituent monomers, (a2) component and (a3) components, (a4), (a5) represents a homopolymer of glass transition temperature (Tg (K)) prepared from, W _a1, W _a2, W _a3, W _a4, W _a5 is contained in each of, (a) component, Represents the weight fraction of the constituent monomers (a1), (a2), (a3), (a4) and (a5).

Further, according to the above equation (1), since Tg _A is calculated as the absolute temperature K, it is converted to the Celsius temperature (占 폚) as required.

The glass transition temperature of a homopolymer prepared from a representative monomer is shown in Table 1 below, and more specifically, it is described in, for example, Polymer Handbook Third Edition (Polymer Handbook Third Edition, Wiley-Interscience, 2003) have.

Monomer Tg (占 폚) Monomer Tg (占 폚) Methyl acrylate 8 Methyl methacrylate 105 Ethyl acrylate -24 Ethyl methacrylate 65 n-propyl acrylate 3 n-propyl methacrylate 35 Isopropyl acrylate -3 Isopropyl methacrylate 61 n-butyl acrylate -50 tert-butyl methacrylate 118 Isobutyl acrylate -40 n-butyl methacrylate 20 tert-butyl acrylate 43 Isobutyl methacrylate 48 n-pentyl acrylate 22 n-pentyl methacrylate -5 n-hexyl acrylate -57 n-hexyl methacrylate -5 n-octyl acrylate -65 n-octyl methacrylate -20 Isooctyl acrylate -58 Isooctyl methacrylate -45 2-ethylhexyl acrylate -70 2-ethylhexyl methacrylate -10 n-nonyl acrylate -58 Isodecyl methacrylate -41 Lauryl acrylate -3 Lauryl methacrylate -65 Tetradecyl acrylate 24 Tetradecyl methacrylate -72 Hexadecyl acrylate 35 Hexadecyl methacrylate 15 Isostearyl acrylate -18 Cyclohexyl acrylate 19 Cyclohexyl methacrylate 65 Isobornyl acrylate 94 Isobornyl methacrylate 180 Phenoxy ethyl acrylate -22 Phenoxyethyl methacrylate 54 Benzyl acrylate 6 Benzyl methacrylate 54 2-naphthyl acrylate 85 Methoxyethyl acrylate -50 Methoxyethyl methacrylate -16 Ethoxyethyl acrylate -50 Ethoxyethyl methacrylate 15 Ethoxy diethylene glycol acrylate -70 Acrylic acid 106 Methacrylic acid 185 Carboxyethyl acrylate 37 Maleic acid 130 Itaconic acid 100 2-hydroxyethyl acrylate -15 2-hydroxyethyl methacrylate 55 2-hydroxypropyl acrylate -7 2-hydroxypropyl methacrylate 26 4-hydroxybutyl acrylate -30 N, N-dimethylaminoethyl acrylate 18 N, N-dimethylaminoethyl methacrylate 18 N, N-dimethylaminoethyl methacrylate 20 Acrylamide 153 N, N-dimethylacrylamide 119 N, N-dimethylaminopropylacrylamide 134 Acrylonitrile 125 Styrene 105 Vinyl acetate 30

1.1.3. Weight average molecular weight

(A) has a weight average molecular weight (Mw) of 50,000 or more and 700,000 or less. On the other hand, when the weight average molecular weight of the component (A) is less than 50,000, the weight average molecular weight of the component (A) , And preferably 100,000 or more and 600,000 or less, and more preferably 150,000 or more and 400,000 or less. Here, the weight average molecular weight of the component (A) is determined by GPC (gel permeation chromatography), and the weight average molecular weight (Mw) in terms of standard polystyrene standards is determined under the following conditions.

≪ GPC measurement condition >

Measuring apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC Column Composition: The following five columns (all manufactured by Tosoh Corporation)

(i) TSK-GEL HXL-H (guard column)

(ii) TSK-GEL G7000HXL

(iii) TSK-GEL GMHXL

(iv) TSK-GEL GMHXL

(v) TSK-GEL G2500HXL

Sample concentration: 1.0 mg / cm3, diluted with tetrahydrofuran

Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0 cm3 / min

Column temperature: 40 DEG C

1.1.4. Hydroxyl group

In the present invention, the hydroxyl value refers to the number of mg of potassium hydroxide (KOH) required to acetylate the hydroxyl group contained in 1 g of the sample. The hydroxyl value can be calculated by the following method.

In the present invention, the hydroxyl value of the polymer is a value calculated from the following formula (2) based on the molecular weight (M) of the hydroxyl group-containing monomer used for copolymerization and the amount of the hydroxyl group monomer (Y mass%) . The hydroxyl value of the polymer (mgKOH) = Y / M x 561 (2)

The hydroxyl value of the copolymer (A) is preferably 15 or more and 150 or less, more preferably 20 or more and 150 or less, still more preferably 20 or more and 130 or less. If the hydroxyl value of the copolymer (A) exceeds 150, the relative dielectric constant of the pressure-sensitive adhesive layer obtained using the optical pressure-sensitive adhesive composition according to the present embodiment may become excessively high. On the other hand, if it is less than 20, Mars may fall behind.

1.1.5. Content in the pressure-sensitive adhesive composition

The content of the component (A) in the pressure-sensitive adhesive composition for an optical device according to the present embodiment may be 70% by mass or more and 99.9% by mass or less, preferably 80% by mass or more and 99.9% Or more and 99.9 mass% or less.

1.1.6 Gel fraction

From the viewpoint of enhancing the durability of the pressure-sensitive adhesive layer obtained by using the optical pressure-sensitive adhesive composition according to the present embodiment and the adhesiveness with the adherend, the gel fraction of the pressure-sensitive adhesive composition for optical use according to the present embodiment is preferably 30% , And more preferably 50% or more and 85% or less.

In the pressure-sensitive adhesive composition for optical use according to the present embodiment, the gel fraction may be, for example, the kind and amount of the component (a3) and the amount of the component (a4) in the monomer mixture used in preparing the pressure- Can be adjusted depending on the type and amount of crosslinking agent used. The gel fraction was obtained by taking 0.1 g (dry weight 1) of the cross-linked pressure-sensitive adhesive on a dry weight basis and further adding 30 cc of ethyl acetate to the sample bottle and shaking it for 24 hours, The contents were separated by filtration with a 200 mesh stainless steel wire net, and the residue on the wire net was dried at 100 占 폚 for 2 hours to measure the dry weight (dry weight 2) and obtained by the following formula (3).

Gel fraction (%) = (dry weight 2) / (dry weight 1) x 100 (3)

1.1.7. Polymerization method

The polymerization method of the component (A) is not particularly limited, and it can be polymerized by a known method such as solution polymerization, emulsion polymerization, suspension polymerization, etc. However, by using a mixture of the copolymer obtained by polymerization, In preparing the pressure-sensitive adhesive composition, it is preferable to polymerize by solution polymerization from the viewpoint that the treatment process is relatively simple and can be performed in a short time.

Solution polymerization is generally carried out by introducing a predetermined organic solvent, each monomer, a polymerization initiator, a chain transfer agent and the like, which are optionally used, into a polymerization vessel and heating and reacting for several hours with stirring under a nitrogen stream or an organic solvent at a reflux temperature Is done.

In this case, at least a part of the organic solvent, the monomer and / or the polymerization initiator may be added successively. Examples of the organic solvent include organic solvents such as benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p- xylene, tetralin, decalin, Aromatic hydrocarbons; For example, aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirit, petroleum naphtha and terphenyl oil; For example, esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate and methyl benzoate; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, and methyl cyclohexanone; For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Glycol ethers such as diethylene glycol monobutyl ether; Examples thereof include alcohols such as methyl alcohol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol. These organic solvents may be used alone or in combination of two or more.

In the polymerization of the component (A), it is preferable to use an organic solvent, such as an ester or a ketone, which hardly causes a chain transfer during the polymerization reaction. Particularly, the solubility of the component (A) , The use of ethyl acetate, methyl ethyl ketone, acetone or the like is preferable in view of ease of polymerization and the like.

As the polymerization initiator, it is possible to use organic peroxides, azo compounds and the like that can be used in ordinary solution polymerization. Such organic peroxides include, for example, tert-butyl hydroperoxide, cumene hydroxides, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, Bis (4,4-di-tert-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di- amyl peroxycyclohexylpropane), 2,2-bis (4,4-di-tert-octylperoxycyclohexyl) propane, 2,2- Di (tert-butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-tert-octylperoxycyclohexyl) Examples of the azo compound include 2,2'-azobis-isobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azo Bis-4- Methoxy-2,4-dimethylvaleronitrile, and the like.

Among these polymerization initiators, a polymerization initiator which does not cause a graft reaction during the polymerization reaction of the component (A) is preferable, and an azo system is particularly preferable. The amount thereof is usually 0.01 parts by mass or more and 2 parts by mass or less, and preferably 0.05 parts by mass or more and 1.0 parts by mass or less, based on 100 parts by mass of the total amount of monomers.

As the chain transfer agent, for example, cyanoacetic acid; Alkyl esters of 1 to 8 carbon atoms in the cyanoacetic acid; Bromoacetic acid; Alkyl esters of bromoacetic acid having 1 to 8 carbon atoms; Aromatic compounds such as anthracene, phenanthrene, fluorene, and 9-phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol and p-nitrotoluene; Benzoquinone derivatives such as benzoquinone and 2,3,5,6-tetramethyl-p-benzoquinone; Borane derivatives such as tributylborane; Halogenated hydrocarbons such as carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichlorethylene, bromotrichloromethane, tribromomethane and 3-chloro-1-propene ; Aldehydes such as chloral, praldehyde and the like; Alkylmercaptans having 1 to 18 carbon atoms; Aromatic mercaptans such as thiophenol and toluene mercaptan; Mercaptoacetic acid, alkyl esters of 1 to 10 carbon atoms in mercaptoacetic acid; Hydroxyalkylmercaptan having 1 to 12 carbon atoms; Terpenes such as pinene and terpinolene, and the like.

The polymerization temperature of the component (A) is generally about 30 ° C or more and 180 ° C or less, preferably 40 ° C or more and 150 ° C or less, and more preferably 50 ° C or more and 90 ° C or less. When an unreacted monomer is contained in the polymer obtained by the solution polymerization method or the like, it may be purified by a re-precipitation method using methanol or the like in order to remove the monomer.

1.2. (B) a crosslinking agent

In the pressure-sensitive adhesive composition for an optical device according to the present embodiment, the component (A) may further include a crosslinkable functional group and (B) a crosslinking agent (sometimes referred to as "component (B)"). The component (B) reacts with the component (A) to form a crosslinked structure, and the pressure-sensitive adhesive layer containing the crosslinked structure is excellent in durability and excellent in adhesion to an adherend (particularly glass).

(B) may be an isocyanate crosslinking agent. (B) is an isocyanate crosslinking agent, it can react with, for example, a hydroxyl group contained in the component (A) to form a crosslinked structure.

In the pressure-sensitive adhesive composition for optical use according to the present embodiment, the component (B) is not particularly limited as long as it is a crosslinking agent capable of crosslinking with the component (A) at room temperature or under heating. Examples thereof include xylylene diisocyanate, Tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, diphenylmethane diisocyanate, Isocyanate compounds such as isocyanate monomers such as diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate and the like, and isocyanate compounds and isocyanurate compounds which are additionally reacted with an alcohol compound having two or more hydroxyl groups such as trimethylolpropane.

Further, urethane prepolymer type isocyanates obtained by subjecting an isocyanate compound to addition reaction with known polyether polyols, polyester polyols, acrylic polyols, polybutadienepolyols, polyisoprene polyols and the like can be given. Of these, hexamethylene diisocyanate, tolylene diisocyanate, and derivatives thereof are preferably used.

The content of the component (B) in the optical pressure-sensitive adhesive composition for an optical element according to the present embodiment is preferably from 100 parts by mass to 100 parts by mass of the component (A) from the viewpoint of achieving a predetermined gel fraction (for example, 30% And more preferably not less than 0.1 part by mass and not more than 10 parts by mass.

1.3. Other ingredients

The optical pressure-sensitive adhesive composition for an optical device according to the present embodiment may further contain components other than components (A) and (B), if necessary. For example, the pressure-sensitive adhesive composition for optical use according to the present embodiment may contain (C) a silane coupling agent (hereinafter sometimes simply referred to as "component (C)") within a range that does not impair the effect of the present invention, An ionic compound, an antioxidant, an ultraviolet absorber, a tackifier, a plasticizer and the like may be blended.

1.3.1. (C) Silane coupling agent

When the pressure-sensitive adhesive composition for optical use according to the present embodiment contains the component (C), when the pressure-sensitive adhesive layer is formed on the surface of the adherend using the optical pressure-sensitive adhesive composition according to the present embodiment, . The component (C) includes, for example, a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane; A silicon compound having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane. ; And 3-chloropropyltrimethoxysilane; An oligomer type silane coupling agent, and the like. Among them, a silane coupling agent having a functional group reactive with a functional group contained in the component (A) is preferable because it is difficult to cause separation under a humid environment.

The content of the component (C) in the pressure-sensitive adhesive composition for optical use according to the present embodiment is preferably 0.1% by mass or more to 5% by mass or more with respect to the pressure-sensitive adhesive composition for optical use according to the present embodiment from the viewpoint of satisfactory adhesion with an adherend. Mass% or less, more preferably 0.2 mass% or more and 1 mass% or less.

1.4. Preparation of pressure-sensitive adhesive composition

The optical pressure-sensitive adhesive composition for an optical device according to the present embodiment is usually prepared by mixing the components (A) and (B) and optional components as needed, either simultaneously or in any order. When the component (A) is prepared by solution polymerization in the mixing of the component (A) and the component (B), the component (B) may be added to the solution containing the component (A) When component (A) is prepared by bulk polymerization, it is difficult to uniformly mix after completion of polymerization, so it is preferable to add component (B) during the polymerization and mix.

1.5. Usage

The pressure-sensitive adhesive composition for optical use according to the present embodiment can be used for bonding with an optical member.

Examples of the optical member to be bonded by using the optical pressure-sensitive adhesive composition according to the present embodiment include a polarizing film (polarizing plate), a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancing film, And an optical film selected from the group consisting of a coat film. As the adherend, for example, a metal layer such as an ITO layer, and a substrate made of glass or plastic can be given. Further, the pressure-sensitive adhesive layer obtained by using the pressure-sensitive adhesive composition for optical use according to the present embodiment can be suitably used for bonding with glass because of its excellent adhesiveness to glass.

The pressure-sensitive adhesive layer obtained by using the optical pressure-sensitive adhesive composition according to the present embodiment has a low dielectric constant and is excellent in adhesive strength and durability. Therefore, the pressure-sensitive adhesive layer can be suitably used for bonding of optical members constituting the touch panel type input- .

1.6. The pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer)

The pressure-sensitive adhesive sheet according to one embodiment of the present invention has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for an optical device according to the present embodiment. The pressure-sensitive adhesive layer may be formed, for example, in the form of a film and removed by removing the solvent.

More specifically, the pressure-sensitive adhesive sheet according to the present embodiment can be obtained, for example, by forming the pressure-sensitive adhesive composition for optical use according to this embodiment on a separator (release film) It is possible to get on doing. More specifically, the optical pressure-sensitive adhesive composition according to the present embodiment is coated on a substrate by a gravure coater, a Meyer bar coater, an air knife coater, a roll coater or the like, and the coated pressure-sensitive adhesive composition thus applied is dried, It is possible to produce a pressure-sensitive adhesive sheet. By providing the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) according to the present embodiment between the adherend and the optical member, bonding of the adherend and the optical member can be performed.

The pressure-sensitive adhesive sheet according to the present embodiment generally has a relative dielectric constant of 4.0 or less (usually 1 or more and 4.0 or less) at 100 Hz, preferably 3.7 or less (1 or more and 3.7 or less) ) Is more preferable.

The thickness of the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) according to the present embodiment is usually from 1 to 250 μm, preferably from 10 to 180 μm.

1.7. Other embodiments

(1) The pressure-sensitive adhesive composition for optical use according to one embodiment of the present invention,

(a) a copolymer (A) of a monomer mixture containing 3 mass% or more and 39 mass% or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms, wherein the weight average And a molecular weight of 50,000 or more and 700,000 or less.

(2) The pressure-sensitive adhesive composition for optical use according to (1) above may have a glass transition temperature (Tg) of 0 占 폚 or less.

(3) The pressure-sensitive adhesive composition for optical use according to (1) or (2) above, wherein the (A) copolymer comprises (a2) 20% by mass of a methacrylic acid alkyl ester monomer having an alkyl group having 1 to 9 carbon atoms, Or more and 97 mass% or less.

(4) The pressure-sensitive adhesive composition for optical use according to one embodiment of the present invention,

(a1) a copolymer of a monomer mixture containing 3 mass% or more and 39 mass% or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms, wherein the glass transition of the copolymer (A) The temperature is 0 ° C or less.

(5) In the pressure-sensitive adhesive composition for optical use according to (4), the weight average molecular weight of the (A) copolymer may be 50,000 or more and 700,000 or less.

(6) The pressure-sensitive adhesive composition for optical use according to the above item (4) or (5), wherein the copolymer (A) comprises (a2) 20% by mass of a methacrylic acid alkyl ester monomer having an alkyl group having 1 to 9 carbon atoms, Or more and 97 mass% or less.

1.8. Action effect

(A1) 3% by mass or more and 39% by mass or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms, (a2) an alkyl group having 1 to 9 carbon atoms (Meth) acrylic acid alkyl ester monomer (a1) and (meth) acrylic acid alkyl ester which is a component (a2) by containing a copolymer (A) of a monomer mixture containing not more than 20% The pressure-sensitive adhesive layer obtained by using the pressure-sensitive adhesive composition for optical use has a low dielectric constant and excellent adhesive strength and durability. Accordingly, the pressure-sensitive adhesive layer can be suitably used, for example, in an image display apparatus or an input / output apparatus.

1.8.1. Configuration of known I / O device

In describing the function and effect of the optical pressure-sensitive adhesive composition according to the present embodiment in more detail, the structure of a known input / output device will be described. 3 is a cross-sectional view schematically showing a configuration of a known input / output device (touch panel type input / output device 200). The touch panel type input / output device 200 includes a liquid crystal display (LCD) 110 and a touch panel unit 120. Since the gap layer 130 is provided at the end portion between the LCD 110 and the touch panel portion 120, a gap 140 is formed between the gap layers 130 at both ends.

In recent years, the display of a touch panel type input / output device is required to have a high contrast. In order to realize high contrast, for example, a means for filling a gap (gap 140 in FIG. 3) between the image display unit and the touch sensor, which was previously a gap, with a transparent material such as an adhesive is adopted. As a result, reflection or refraction of light between the respective interfaces is suppressed, and as a result, high contrast can be achieved.

However, when the member 140 is bonded to the cavity 140 in FIG. 3 by bonding an adhesive or the like, high-frequency noise generated from the internal circuit of the apparatus or charge of the member may cause malfunction of the touch sensor. In the touch panel type input / output device in which a gap is formed between the image display portion and the touch sensor (in particular, the capacitive touch sensor), since the relative dielectric constant of the air layer of the gap is 1, noise is blocked by the gap formed by the air layer Therefore, occurrence of malfunction is prevented. On the other hand, when a transparent resin (for example, an acrylic pressure-sensitive adhesive having a relative dielectric constant of 4 or more) is used as a filler in order to fill the gap between the image display unit and the touch sensor, high frequency noise propagates to the touch sensor, have. In addition, due to the gap 140, adhesion between the LCD 110 and the touch panel portion 120 may be insufficient.

In view of such a situation, it is desired to fill the gap between the image display section and the touch sensor by using a pressure-sensitive adhesive layer having a low relative dielectric constant and an excellent adhesive force in the touch panel type input / output device.

1.8.2. Action and effect of the present invention

On the other hand, according to the pressure-sensitive adhesive composition for an optical device according to the present embodiment, a pressure-sensitive adhesive layer having a low relative dielectric constant and excellent adhesive force can be obtained by using the pressure-sensitive adhesive composition for optical use. Thus, malfunction of the touch sensor due to the high relative dielectric constant of the pressure-sensitive adhesive layer can be prevented. That is, in the input / output device 300 of FIG. 2 to be described later, the gap 140 of FIG. 2 is filled using the optical pressure-sensitive adhesive composition according to the present embodiment having excellent adhesive force, and a pressure- Is provided in the gap 140, malfunction of the touch sensor can be prevented. The pressure sensitive adhesive layer 32 obtained by using the optical pressure sensitive adhesive composition according to the present embodiment is excellent in adhesion so that the pressure sensitive adhesive layer 32 is disposed on the gap 140, (120) can be surely bonded.

For example, in the touch panel type input / output device (first input / output device) 100 according to the present embodiment shown in FIG. 1, a pressure sensitive adhesive layer 30 is installed between the LCD 10 and the touch panel portion 20 Since the pressure-sensitive adhesive layer 30 is formed of the optical pressure-sensitive adhesive composition according to the present embodiment, the relative dielectric constant is as low as 4.0 or less, so that the malfunction of the touch sensor due to the high relative dielectric constant of the pressure- Further, since the adhesive force is excellent, the LCD 10 and the touch panel unit 20 can be reliably bonded.

2. Image display device and input / output device

An image display apparatus according to an embodiment of the present invention includes a pressure-sensitive adhesive layer obtained by using the optical pressure-sensitive adhesive composition according to the present embodiment. The image display device according to the present embodiment is, for example, a liquid crystal display device.

Further, the input / output device according to one embodiment of the present invention includes a pressure-sensitive adhesive layer obtained using the optical pressure-sensitive adhesive composition according to the present embodiment. In this case, the input / output device is, for example, a capacitive touch panel type input / output device.

2.1. The first input /

The touch panel type input / output device (first input / output device) 100 according to the present embodiment shown in Fig. 1 will be described in detail below.

1 is a cross-sectional view schematically showing the configuration of an input / output device (touch panel type input / output device 100) according to an embodiment of the present invention. The touch panel type input / output device 100 according to the present embodiment includes a liquid crystal display (LCD) 10, a touch panel unit 20, a pressure sensitive adhesive layer (30). The pressure sensitive adhesive layer (30) bonds the LCD (10) and the touch panel portion (20).

The pressure sensitive adhesive layer 30 is formed by applying the pressure sensitive adhesive composition for optical use according to the present embodiment to the surface of a separator (not shown), removing the solvent, peeling the obtained pressure sensitive adhesive sheet from the separator, And the touch panel (20).

1, the LCD 10 includes a polarizing plate 11, a pressure-sensitive adhesive layer 12, a liquid crystal panel 13, a pressure-sensitive adhesive layer 14, and a polarizing plate 15 stacked in this order Consists of. The pressure sensitive adhesive layer 12 adheres the polarizing plate 11 and the liquid crystal panel 13 and the pressure sensitive adhesive layer 14 adheres the liquid crystal panel 13 and the polarizing plate 15.

1, the touch panel section 20 is formed by stacking the scattering prevention film 16, the pressure-sensitive adhesive layer 17, the ITO layer 18, and the glass panel 19 in this order Consists of. The pressure-sensitive adhesive layer 17 bonds the anti-scattering film 16 and the ITO layer 18.

The pressure-sensitive adhesive layers 12, 14, and 17 are manufactured using the pressure-sensitive adhesive composition for an optical device according to the present embodiment, like the pressure-sensitive adhesive layer 30. The pressure-sensitive adhesive layers (12), (14), (17) and (30) obtained by using the optical pressure-sensitive adhesive composition according to the present embodiment are excellent in adhesion, Further, since the pressure-sensitive adhesive layers 12, 14, 17, and 30 have a low dielectric constant, malfunction of the touch sensor can be prevented.

2.2. The second input /

2 is a cross-sectional view schematically showing a configuration of a second input / output device (touch panel type input / output device) 300 according to an embodiment of the present invention. The touch panel type input / output device 300 includes a liquid crystal display device (LCD) 110 and a touch panel part 120 like the input / output device 200 of FIG. Since the gap layer 130 is formed at the end portion between the LCD 110 and the touch panel portion 120, a gap 140 is formed between the gap layer 130 at both ends.

The adhesive layer 32 is provided on the gap 140 to adhere the LCD 110 to the touch panel unit 120. The pressure-sensitive adhesive layer (32) has a relative dielectric constant of 4.0 or less. The touch panel type input / output device 300 of FIG. 2 is configured such that the gap 140 of FIG. 3 is filled using the optical pressure-sensitive adhesive composition according to the present embodiment, and the pressure-sensitive adhesive layer 32 is formed on the gap 140 , And joining the LCD 110 and the touch panel unit 120 to each other. In the touch panel type input / output device 300, since the pressure sensitive adhesive layer 32 having the relative dielectric constant of 4.0 or less is formed in the gap 140, malfunction of the touch sensor can be prevented.

Since the pressure-sensitive adhesive layer 32 obtained by using the optical pressure-sensitive adhesive composition according to the present embodiment is excellent in adhesive strength, the pressure-sensitive adhesive layer 32 is disposed on the gap 140, The panel part 120 can be securely bonded.

3. Example

Hereinafter, the present invention will be described based on the following examples, but the present invention is not limited to the examples.

3.1. Preparation of the component (A)

3.1.1. Preparation of Polymer 1

80 parts by mass of ethyl acetate as a solvent, 35 parts by mass of methacrylate lauryl as a monomer component and 44 parts by mass of 2-ethylhexyl methacrylate as a solvent were added to a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, a dropping funnel and a stirrer 20 parts by mass of hydroxyethyl methacrylate and 1 part by mass of acrylamide were charged and the temperature of the solution of the monomer composition solution in the reaction vessel was raised to 80 ° C by nitrogen reflux at room temperature for 1 hour. And 0.2 parts by mass of bisisobutyronitrile were added with stirring. Followed by polymerization in a nitrogen stream for 10 hours to obtain a solution of a copolymer (polymer 1) having a weight average molecular weight of 200,000. The Tg and the hydroxyl value of the polymer 1 are shown in Table 2 as well.

3.1.2. Preparation of polymers 2 to 6, 10 to 17 and 19

Solutions of Polymers 2 to 6, 10 to 17 and 19 were respectively obtained by the method described in Production Example 1, except that the monomer mixture having the composition shown in Table 2 was used. The weight average molecular weights, Tg and hydroxyl value of Polymers 2 to 6, 10 to 17 and 19 and Polymers 7 to 9 and 18 described later are shown in Table 2 as well.

3.1.3. Preparation of Polymer 7

Polymer 7 was obtained by the method described in Preparation Example 1, except that 0.3 part by mass of 2,2'-azobisisobutyronitrile was used as a polymerization initiator in the method described in Production Example 1.

3.1.4. Preparation of Polymer 8

Polymer 8 was obtained by the method described in Preparation Example 1 except that 0.12 part by mass of 2,2'-azobisisobutyronitrile was used as a polymerization initiator in the method described in Production Example 1. [

3.1.5. Preparation of polymer 9

Polymer 9 was obtained by the method described in Preparation Example 1 except that 0.08 part by mass of 2,2'-azobisisobutyronitrile was used as a polymerization initiator in the method described in Production Example 1.

3.1.6. Preparation of Polymer 18

Azobisisobutyronitrile as a polymerization initiator was changed to 0.08 part by mass, and as a monomer component, 99 parts by mass of methacrylic acid lauryl, 4 parts by mass of 4-hydroxybutyl acrylate 1 Polymer 18 was obtained in the same manner as in Production Example 1,

3.2. Preparation of pressure-sensitive adhesive composition (Examples 1 to 14 and Comparative Examples 1 to 5)

Each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 was obtained by mixing the polymers 1 to 19 and the components (B) shown in Table 2 in the ratios shown in Table 3.

3.3. Production of pressure-sensitive adhesive sheet for evaluation

Each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 was coated on the surface of the separator to remove the solvent and the separator was bonded to the adhesive surface to obtain a pressure-sensitive adhesive sheet having a thickness of 50 mu m . One separator of the obtained pressure-sensitive adhesive sheet was peeled off and a polyethylene terephthalate film having a thickness of 100 占 퐉 was bonded to obtain a pressure-sensitive adhesive sheet for evaluation.

3.4. Test Methods

An evaluation test was conducted on each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 and the pressure-sensitive adhesive sheet obtained using the composition in the following manner.

3.4.1. Gel fraction

1 g of the sample (composition) was put into 50 ml of ethyl acetate, left at room temperature for 24 hours, filtered through a 200-mesh stainless steel screen, and dried. Thereafter, the mass of the sample after filtration divided by the mass of the sample before filtration was calculated as a gel fraction.

3.4.2. The haze change value before and after the wet heat test (whitening resistance)

A separator on one side of the pressure-sensitive adhesive sheet prepared in the above-mentioned 3.3 was peeled off, and a pressure-sensitive adhesive layer was adhered to the glass substrate by using a laminator roll to prepare a measurement sample and measured with a haze meter (Model: HM- Murakami Color Research Institute) (initial Haze). Then, the sample was placed under the condition of 60 ° C-95% RH for 500 hours, and then moved under the condition of 23 ° C-50% RH. After 10 minutes, the haze was measured (haze after wet heat test). It is preferable that the change value of the haze before and after the wet heat test (the haze after the wet heat test - the initial haze) is 3 or less, more preferably 2.5 or less.

3.4.3. 180 ° Adhesion

The pressure-sensitive adhesive sheet for evaluation prepared in the above 3.3 was cut into a size of 25 mm x 150 mm and the separator of the pressure-sensitive adhesive sheet obtained in Examples and the like was peeled off on a glass plate under the condition of 23 ° C- And pressed using a roller. Twenty minutes after the attachment, the adhesive sheet was peeled off from the glass plate at a peeling rate of 300 mm / min under conditions of a temperature of 23 ° C and a peeling angle of 180 ° to measure the adhesive strength of the adhesive layer of the adhesive sheet.

3.4.4. Durability (heat and humidity test)

The pressure-sensitive adhesive sheet for evaluation prepared in the above 3.3 was cut into a size of 50 mm x 60 mm and the separator on one side was peeled off and adhered to one side of a polycarbonate plate (adherend) using a laminator roll, The autoclave was adjusted to 5 atm for 20 minutes to prepare a test plate. And allowed to stand for 24 hours under the conditions of 85 ° C and 85% RH, and the appearance of peeling and foaming of the interface of the polycarbonate plate-pressure-sensitive adhesive layer was visually confirmed on the basis of the following criteria.

(standard)

?: No foaming in the pressure-sensitive adhesive layer or lifting from the adherend was observed.

?: Either the foaming in the pressure-sensitive adhesive layer or the exfoliation from the adherend was slightly observed.

X: Either the foaming in the pressure-sensitive adhesive layer or the exfoliation from the adherend was clearly observed.

3.4.5. Relative dielectric constant

Each of the compositions of Examples 1 to 14 and Comparative Examples 1 to 5 was applied to the surface of a separator to remove the solvent to obtain a pressure-sensitive adhesive layer having a thickness of 100 m. Another separator was bonded to the adhesive surface of the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer. Next, a separator on one side of the obtained pressure-sensitive adhesive sheet was peeled and attached to a copper foil having a thickness of 100 占 퐉, and a separator on the other side was peeled off and bonded to a copper foil having a thickness of 100 占 퐉 to obtain a measurement sample. The dielectric constant (100 Hz) was calculated under the conditions of 23 ° C. and 65% RH by connecting to a copper foil using a LCR meter 6440B manufactured by Toyotechnica.

The abbreviations in Tables 2 and 3 mean the following.

AM: Acrylamide

nBMA: n-butyl methacrylate

2EHA: 2-ethylhexyl acrylate

2EHMA: 2-ethylhexyl methacrylate

4HBA: 4-hydroxybutyl acrylate

HEMA: 2-hydroxyethyl methacrylate

HPMA: 2-hydroxypropyl methacrylate

LA: Lauryl acrylate

LMA: Lauryl methacrylate

Isodecyl MA: isodecyl methacrylate

Coronate L: tolylene diisocyanate crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd.)

The composition of Examples 1 to 14 is a composition containing 3 mass% or more and 39 mass% or less (more specifically, 3 mass% or more and 39 mass% or less of component (a1) and 20 mass% or less of component (a2) Or more and 97 mass% or less), it is understood that the pressure-sensitive adhesive layer obtained using the composition has a low relative dielectric constant (4.0 or less) and excellent adhesive strength, durability, and heat and humidity resistance.

On the other hand, in the composition of Comparative Example 1, since the monomer mixture for preparing the component (A) contains no component (a1), the pressure-sensitive adhesive layer becomes too hard to adhere to the base material and is electrodeposited, In addition, the heat and humidity test is generated.

The composition of Comparative Example 2 is such that the content of the component (a1) in the monomer mixture for preparing the component (A) exceeds 39% by mass and the content of the methacrylate ester monomer in the monomer mixture It is understood that the durability is poor and the relative dielectric constant is high (the relative dielectric constant exceeds 4.0) because it is less than 80 mass%.

The composition of Comparative Example 3 is an example in which the monomer mixture for preparing the component (A) contains no component (a1), lauryl acrylate is used in place of the component (a1) Lt; 0 > C. For this reason, the pressure-sensitive adhesive layer obtained using the component (A) is hard, so that the pressure-sensitive adhesive layer is electrodeposited, resulting in deteriorated adhesive force and lifting. In addition, the pressure-sensitive adhesive layer obtained using the component (A) has a high relative dielectric constant (relative dielectric constant exceeding 4.0).

The composition of Comparative Example 4 was such that the content of the component (a1) in the monomer mixture for preparing the component (A) greatly exceeded 39 mass% (99 mass%), And the durability is also inferior.

Further, it is understood that the composition of Comparative Example 5 lacks the component (a2) in the monomer mixture for preparing the component (A), and the adhesive strength is poor.

10, 110: liquid crystal display (LCD)
11, 15: polarizer
12, 14, 17: pressure-sensitive adhesive layer
13: liquid crystal panel
16: Shatterproof film
18: ITO layer
19: Glass panel (touch panel)
30, 32: pressure-sensitive adhesive layer
20, 120: Touch panel section
130:
140: Clearance
100, 200, 300: Touch panel type input / output device

Claims (19)

(a1) 3% by mass or more and 39% by mass or less of a methacrylic acid alkyl ester monomer having an alkyl group of 10 to 18 carbon atoms,
(a2) a copolymer of a monomer mixture containing 20% by mass or more and 97% by mass or less of a methacrylic acid alkyl ester monomer having an alkyl group of 1 to 9 carbon atoms,
Wherein the total of the component (a1) and the component (a2) is 45 mass% or more and 100 mass% or less. The optical pressure-sensitive adhesive composition for optical use according to claim 1, wherein the (A) copolymer has a weight average molecular weight of 50,000 or more and 700,000 or less. The pressure-sensitive adhesive composition for optical use according to claim 1, wherein the (A) copolymer has a glass transition temperature (Tg) of 0 ° C or lower. The optical pressure-sensitive adhesive composition for optical use according to claim 1, wherein in the monomer mixture, the content of the component (a2) relative to the content of the component (a1) is 0.5 or more and 5 or less. The optical pressure-sensitive adhesive composition for optical use according to claim 1, further comprising (a3) 2% by mass or more and 30% by mass or less of the hydroxyl group-containing monomer. The pressure-sensitive adhesive composition for optical use according to claim 5, wherein the (a3) hydroxyl group-containing monomer is a methacrylic acid ester monomer containing a hydroxyl group. The optical pressure-sensitive adhesive composition for optical use according to claim 1, wherein the monomer mixture further comprises (a4) 0.1 mass% or more and 5 mass% or less of nitrogen atom-containing monomer. The optical pressure-sensitive adhesive composition for optical use according to claim 1, wherein the total amount of methacrylic acid ester monomers in the monomer mixture is 80% by mass or more and 100% by mass or less. The pressure-sensitive adhesive composition for optical applications according to claim 1, wherein the content of the copolymer (A) in the pressure-sensitive adhesive composition is 70% by mass or more and 99.9% by mass or less. The pressure-sensitive adhesive composition for optical use according to claim 1, wherein the hydroxyl value of the copolymer (A) is 15 or more and 150 or less. The optical pressure-sensitive adhesive composition for optical use according to claim 1, wherein the gel fraction of the (A) copolymer is 30% or more and 90% or less. The positive resist composition according to claim 1, wherein the (A) copolymer has a crosslinkable functional group,
(B) a crosslinking agent. The optical pressure-sensitive adhesive composition for optical use according to claim 12, which comprises 0.01 to 20 parts by mass of the crosslinking agent (B) relative to 100 parts by mass of the copolymer (A). The pressure-sensitive adhesive composition for optical use according to claim 12, wherein the crosslinking agent (B) is an isocyanate-based crosslinking agent. The optical pressure-sensitive adhesive composition for optical use according to claim 1, which is used for bonding a member constituting a touch panel type input / output device or an image display device. A pressure-sensitive adhesive sheet for optical use comprising a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition for optical use according to any one of claims 1 to 15. The optical adhesive sheet for optical use according to claim 16, wherein the specific dielectric constant at 100 Hz is 4.0 or less. An image display device comprising the optical adhesive sheet according to claim 16. An input / output device comprising the optical adhesive sheet according to claim 16.

Images