KR20180111468A - Solventless type adhesive compositon, adhesive, and manufacturing method of adhesive - Google Patents

Abstract

Provided is a solventless adhesive composition which stably secures basic characteristics required for an adhesive obtained by curing the same, does not raise specific dielectric constant in the obtained adhesive, and ensures excellent wet/heat/whitening resistance and blister resistance. Moreover, provided are an adhesive and an adhesive sheet. To this end, the solventless adhesive composition contains the following ingredients: (a) 100 parts by weight of a (meth)acrylic acid ester monomer having an alkyl group with 4 to 20 carbon atoms; (b) 1-100 parts by weight of a (meth)acrylic acid ester monomer having an alicyclic hydrocarbon skeleton; (c) 1-60 parts by weight of a polar vinyl monomer; (d) 0.1-50 parts by weight of N-vinylcarboxylic acid amide; and (e) 10-200 parts by weight of urethane (meth)acrylate.

Description

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

The present invention relates to a solvent-free (solvent-free) pressure-sensitive adhesive composition, a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

Particularly, it is possible to stably obtain the basic characteristics required for a pressure-sensitive adhesive composition of the present invention without any increase in the relative dielectric constant, and to obtain excellent heat and moisture whitening properties, A pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet.

Conventionally, in a capacitive touch panel, a glass plate or an acrylic plate as a top plate is usually laminated on the visible side of the conductive pattern layer via a hard coat film.

At this time, adhesion of the hard coat film to the conductive pattern layer or the like is often carried out by providing a pressure-sensitive adhesive layer only on the outer peripheral portion of the laminated surface in consideration of reworkability and ease of cohesion.

In this case, an air gap is formed between the hard coat film and the conductive pattern layer.

However, such an air gap is a cause of the difference in refractive index between the hard coat film and the conductive pattern layer, and therefore causes a decrease in brightness and contrast due to scattering of light, and furthermore, causes a decrease in the visibility of the screen .

Therefore, in recent years, a technique of providing a thick film layer made of an optical transparent pressure-sensitive adhesive (OCA) on the entire surface of the laminated surface of the hard coat film and the conductive pattern layer and filling the air gap has started to be employed.

Further, in such applications, the OCA is applied at the outermost surface side of the touch panel image display device, so that whitening phenomenon due to intrusion of moisture from the outside tends to occur.

Thus, as a constituent component of OCA, there has been disclosed a method of compatibilizing and dispersing water intruded into OCA by blending a hydrophilic monomer at a predetermined ratio to improve anti-wet heat resistance (see, for example, Patent Document 1).

That is, Patent Document 1 discloses the following (a-1) to (a-3)

(a-1) 40 to 92% by weight of an alkyl (meth)

(a-2) 5 to 20% by weight of a hydroxyl group-

(a-3) 3 to 25% by weight of water-soluble N-substituted acrylamide,

Based crosslinking agent and / or an isocyanate-based crosslinking agent and / or an isocyanate-based crosslinking agent, based on 100 parts by weight of a monomer group (A) substantially containing no acidic group-containing monomer (total monomer is 100% 0.01 to 2 parts by weight of a polyfunctional monomer (B) and 0.1 to 2 parts by weight of a photopolymerization initiator (C).

Japanese Patent Laid-Open No. 2013-256552 (Claims)

However, since the photopolymerizable pressure-sensitive adhesive described in Patent Document 1 contains a hydroxyl group-containing monomer, which is a hydrophilic monomer, and a water-soluble N-substituted acrylamide at a predetermined ratio, And it became difficult to obtain blistering property.

Further, when such blistering property becomes insufficient, an outgass originating from the adherend is accumulated at the interface between the adherend and OCA, resulting in an optical obstacle. Therefore, blister resistance is a property of the basic properties required for OCA It is one.

On the other hand, when the water-soluble N-substituted acrylamide is omitted in the photopolymerizable pressure-sensitive adhesive of Patent Document 1, not only the anti-wet heat resistance is excessively lowered but also the cohesive force of the pressure-sensitive adhesive is easily lowered.

In addition, when a large amount of the hydroxyl group-containing monomer is used in order to supplement the water-soluble N-substituted acrylamide, the moisture resistance whitening whiteness is obtained, but the relative dielectric constant becomes excessively high and the malfunction of the touch panel tends to occur A problem appeared.

(Meth) acrylic acid ester monomer having an alkyl group, a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton, and a polar vinyl monomer having an alicyclic hydrocarbon skeleton. The present invention has been made in view of the above- , And N-vinylcarboxylic acid amide and urethane (meth) acrylate at a predetermined ratio, it is possible to stably obtain the basic properties required for the pressure-sensitive adhesive composition without a solvent-form and the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition, And that excellent anti-wet heat and whitening resistance can be obtained without raising the relative dielectric constant, thereby completing the present invention.

That is, an object of the present invention is to provide a pressure-sensitive adhesive which can stably obtain basic characteristics required for a solvent-free pressure-sensitive adhesive composition and a pressure-sensitive adhesive obtained by curing the pressureless pressure-sensitive adhesive composition, A pressure-sensitive adhesive composition, and a pressure-sensitive adhesive sheet.

According to the present invention, there is provided a solvent-free pressure-sensitive adhesive composition which comprises the following components (a) to (e), whereby the above-mentioned problems can be solved.

(a) a (meth) acrylic acid ester monomer having an alkyl group having 4 to 20 carbon atoms

                                                              100 parts by weight

(b) a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton

                                                           1 to 100 parts by weight

(c) 1 to 60 parts by weight of a polar vinyl monomer

(d) N-vinylcarboxylic acid amide 0.1 to 50 parts by weight

(e) 10 to 200 parts by weight of urethane (meth) acrylate

That is, since the non-solvent-type pressure-sensitive adhesive composition of the present invention contains the polar vinyl monomer and the N-vinylcarboxylic acid amide in a predetermined ratio, the moisture content derived from the external environment and the compatibility with the resulting pressure- It is possible to improve the properties effectively and to impart excellent anti-wet heat and whitening properties.

In addition, since the (meth) acrylic acid ester monomer having a predetermined alkyl group is contained, excellent tackiness can be imparted to the obtained pressure sensitive adhesive.

In addition, since the (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton is contained in a predetermined ratio, the viscosity of the solventless pressure-sensitive adhesive composition can be adjusted to a favorable range by its excellent dilution property, The cohesiveness of the obtained pressure-sensitive adhesive can be improved by improving the curability.

In addition, since N-vinylcarboxylic acid amide also has an effect of improving the cohesive force of the resulting pressure-sensitive adhesive, it is excellent in blister resistance to the resulting pressure-sensitive adhesive in combination with the action of the (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton can do.

Further, since urethane (meth) acrylate is contained in a predetermined ratio, a predetermined flexibility can be imparted to the resulting pressure-sensitive adhesive, and further excellent step-following ability can be obtained.

In the present invention, the polar vinyl monomer as the component (c) is defined as not containing the N-vinylcarboxylic acid amide as the component (d).

In the pressure-sensitive adhesive composition of the present invention, the ratio of the polar vinyl monomer as component (c) to the N-vinylacetamide as component (d) (component (c): component (d) ) Is set to a value within a range of 90:10 to 10:90.

By such a constitution, it is possible to obtain excellent anti-wet heat and whitening resistance while suppressing an increase in the relative dielectric constant more effectively.

Further, in constituting the solvent-free pressure-sensitive adhesive composition of the present invention, it is preferable that the polar vinyl monomer as the component (c) is a vinyl monomer having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group and an amide group .

By such a constitution, excellent moisture heat and whitening flammability can be obtained by excellent hydrophilicity.

Further, in constituting the solvent-free pressure-sensitive adhesive composition of the present invention, it is preferable that the N-vinylcarboxylic acid amide as the component (d) is a compound represented by the following general formula (1).

(In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ² represents an alkyl group having 1 to 4 carbon atoms)

By such a constitution, excellent anti-wet heat and whitening resistance and blister resistance can be obtained while suppressing the increase of the relative dielectric constant more effectively.

In forming the pressure-sensitive adhesive composition of the present invention, the weight average molecular weight of the urethane (meth) acrylate as the component (e) is preferably within the range of 3,000 to 20,000.

By such a constitution, it is possible to obtain a better step traceability.

In forming the solventless pressure-sensitive adhesive composition of the present invention, it is preferable that the photopolymerization initiator as the component (f) is contained in a range of 0.1 to 20 parts by weight based on 100 parts by weight of the component (a).

This constitution makes it possible to more easily constitute the pressure-sensitive adhesive composition as a solvent-free pressure-sensitive adhesive composition, and it is not necessary to apply heat to cure the pressure-sensitive adhesive composition without solvent, Thermal degradation (heat deterioration), and heat shrinkage can be prevented.

In forming the solventless pressure-sensitive adhesive composition of the present invention, it is preferable that the silane coupling agent as the component (g) is contained in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the component (a).

By such a constitution, the tackiness of the resulting pressure-sensitive adhesive can be improved more effectively.

Further, another embodiment of the present invention is a pressure-sensitive adhesive obtained by photo-curing the above-mentioned pressure-sensitive adhesive composition of no-solvent-type.

That is, since the pressure-sensitive adhesive of the present invention is formed by curing a predetermined solvent-free pressure-sensitive adhesive composition, it is possible to exhibit excellent anti-wet heat and whitening properties while effectively suppressing an increase in relative dielectric constant as well as basic properties such as excellent adhesive force and cohesive force, In addition, excellent blister resistance and step-like followability can be exhibited.

Still another aspect of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the above-mentioned pressure-sensitive adhesive on a substrate.

That is, since the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer composed of a predetermined pressure-sensitive adhesive, it is possible to exhibit excellent moisture and heat whitening properties while effectively suppressing the increase of the relative dielectric constant as well as basic properties such as excellent adhesive force and cohesive force, In addition, excellent blister resistance and step-like followability can be exhibited.

1 (a) to 1 (c) are diagrams for explaining a production method of a pressure-sensitive adhesive of the present invention.
Figs. 2 (a) to 2 (d) are views for explaining a method for producing a pressure-sensitive adhesive of the present invention. Fig.
3 is a view for explaining an application example of the pressure-sensitive adhesive of the present invention.

[First Embodiment]

A first embodiment of the present invention is a solventless pressure-sensitive adhesive composition, which comprises the following components (a) to (e).

(a) a (meth) acrylic acid ester monomer having an alkyl group having 4 to 20 carbon atoms

                                                              100 parts by weight

(b) a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton

                                                           1 to 100 parts by weight

(c) 1 to 60 parts by weight of a polar vinyl monomer

(d) N-vinylcarboxylic acid amide 0.1 to 50 parts by weight

(e) 10 to 200 parts by weight of urethane (meth) acrylate

Hereinafter, the solventless pressure-sensitive adhesive composition of the first embodiment of the present invention will be specifically described with reference to the drawings (as appropriate).

1. Component (a): (meth) acrylic acid ester monomer having a predetermined alkyl group

The solvent-free pressure-sensitive adhesive composition of the present invention is characterized by containing as its component (a) a (meth) acrylic acid ester monomer having an alkyl group having 4 to 20 carbon atoms.

This is because the inclusion of the (meth) acrylic acid ester monomer having such a predetermined alkyl group can impart excellent tackiness to the resulting pressure-sensitive adhesive.

(1) Type

Examples of the kind of the component (a) include, but are not limited to, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, lauryl (meth) acrylate, and the like, alone or in combination of two or more selected from the group consisting of (meth) acrylic acid, methacrylic acid, It is preferable to use a combination of two or more.

Among them, the alkyl group preferably has 6 to 14 carbon atoms, more preferably 8 to 10 carbon atoms.

Therefore, specifically, it is particularly preferable to use 2-ethylhexyl (meth) acrylate or isooctyl (meth) acrylate.

(2) Amount

The blending amount of the component (a) is set to 100 parts by weight as a standard of the blending amount of all components in the solventless pressure-sensitive adhesive composition.

When two or more components (a) are used in combination, the total amount of these two or more components (a) is 100 parts by weight.

2. Component (b): (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton

The solventless pressure-sensitive adhesive composition of the present invention is characterized by containing a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton as the component (b).

The reason for this is that by including the (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton, the viscosity of the solventless pressure-sensitive adhesive composition can be adjusted to a favorable range owing to its excellent dilution property. Further, I can get a castle.

In addition, since the curable property of the solvent-free pressure-sensitive adhesive composition is improved and the cohesive force of the resulting pressure-sensitive adhesive is improved, it is possible to obtain excellent blister resistance to the pressure-sensitive adhesive to be obtained in combination with the action of N-vinylcarboxylic acid amide .

(1) Type

The kind of the component (b) is not particularly limited, but the alicyclic hydrocarbon skeleton is preferably a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a dicyclo decane ring, a tricyclodecane ring, an isobornyl ring, It is preferable to use a bullet or the like.

Among them, it is preferable that the alicyclic hydrocarbon skeleton portion has a plurality of cyclic structures. For example, the alicyclic hydrocarbon skeleton portion includes at least a dicyclodecane ring, a tricyclodecane ring, an isobornyl ring and an adamantane ring It is more preferable to use one species.

This is because, when such a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton moiety is used, the viscosity of the solventless pressure-sensitive adhesive composition can be more easily controlled and the cohesive force of the obtained pressure-sensitive adhesive can be further improved.

(2) Amount

Further, the blending amount of the component (b) is set to a value within a range of 1 to 100 parts by weight based on 100 parts by weight of the component (a).

This is because when the blending amount of the component (b) is less than 1 part by weight, the viscosity of the solventless pressure-sensitive adhesive composition becomes excessively large and the coating property becomes insufficient, the hardness of the solventless pressure- It may be difficult to impart a sufficient cohesive force to the surface layer. On the other hand, when the blending amount of the component (b) exceeds 100 parts by weight, the curing property of the solventless pressure-sensitive adhesive composition becomes excessively high, and the stepwise followability of the obtained pressure-sensitive adhesive may be excessively lowered.

Therefore, the lower limit of the blending amount of the component (b) is more preferably 10 parts by weight or more, and more preferably 20 parts by weight or more.

The upper limit of the blending amount of the component (b) is more preferably 80 parts by weight or less, and still more preferably 60 parts by weight or less.

3. Component (c): Polar vinyl monomer

The solventless pressure-sensitive adhesive composition of the present invention is characterized by containing a polar vinyl monomer as the component (c).

The reason for this is that the inclusion of a polar vinyl monomer effectively improves the compatibility of the water derived from the external environment with the resulting pressure sensitive adhesive by virtue of its excellent hydrophilicity and thereby achieves excellent anti wet heat and whitening properties.

(1) Type

The kind of the component (c) is not particularly limited, but it is preferable to use a vinyl monomer having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group and an amide group.

This is because vinyl monomers having such a functional group have excellent hydrophilicity and therefore, excellent anti-wet heat and whitening properties can be obtained.

Thus, for example, there can be mentioned (meth) acrylic acid esters such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (Meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl and 4-hydroxybutyl (meth) acrylate; (Meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide and the like; acrylamides such as NN- - (meth) acryloylmorpholine, NN-diethylaminoethyl (meth) acrylate; (Meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and the like, or a combination of two or more thereof.

Among them, it is preferable to use 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate.

In the present invention, the polar vinyl monomer as the component (c) is defined as not containing the N-vinylcarboxylic acid amide as the component (d).

(2) Amount

The component (c) is added in an amount of 1 to 60 parts by weight based on 100 parts by weight of the component (a).

This is because when the blending amount of the component (c) is less than 1 part by weight, it may be difficult to impart a sufficient anti-wet heat whitening property to the obtained pressure sensitive adhesive. On the other hand, when the blending amount of the component (c) exceeds 60 parts by weight, the anti-wet heat resistance can be improved, but the relative dielectric constant of the resulting pressure sensitive adhesive becomes excessively high, , Malfunction of the touch panel may easily occur.

Therefore, the lower limit of the amount of the component (c) is more preferably 5 parts by weight or more, and more preferably 10 parts by weight or more.

The upper limit of the amount of the component (c) is more preferably 45 parts by weight or less, and more preferably 30 parts by weight or less.

The blending amount of the component (c) with respect to the solventless pressure-sensitive adhesive composition (100 wt%) is preferably at least 1 wt%, more preferably at least 4.5 wt% By weight and particularly preferably at least 8% by weight.

On the other hand, from the viewpoint of suppressing the relative dielectric constant, the value is preferably 30% by weight or less, more preferably 20% by weight or less, particularly preferably 15% by weight or less.

4. Component (d): N-vinylcarboxylic acid amide

The solventless pressure-sensitive adhesive composition of the present invention is characterized by containing an N-vinylcarboxylic acid amide as a component (d).

This is because, by including N-vinylcarboxylic acid amide, a superior hydrophilicity is manifested by the synergistic effect with the polar vinyl monomer as the above-mentioned component (c), and the moisture derived from the external environment and the compatibility And more excellent anti-wet heat and whitening properties can be obtained.

As a result, it is possible to effectively reduce the blending amount of the polar vinyl monomer, and to obtain the desired anti-wet heat whitening property while effectively suppressing the rise of the relative dielectric constant in the obtained pressure sensitive adhesive.

In addition, since it has an action to improve the cohesive force of the obtained pressure sensitive adhesive, it is possible to impart excellent blister resistance to the obtained pressure sensitive adhesive in combination with the action of the (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton as the component (b) have.

(1) Type

The kind of the component (d) is not particularly limited, but is preferably a compound represented by the following general formula (1).

(In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ² represents an alkyl group having 1 to 4 carbon atoms)

This is because, if such a compound is used, it is possible to obtain excellent anti-wet heat and whitening properties while suppressing the rise of the relative dielectric constant more effectively.

Thus, for example, there may be mentioned N-vinylformamide, N-methyl-N-vinylformamide, N-ethyl- But are not limited to, formamide, N-butyl-N-vinylformamide, N-isobutyl-N-vinylformamide, N-vinylacetamide, N-vinylacetamide, N-isopropyl-N-vinylacetamide, N-isopropyl-N-vinylacetamide, Vinylpropionamide, N-ethyl-N-vinylpropionamide, N-ethyl-N-vinylpropionamide, N-isopropyl- Vinyl propionic amide, N-isobutyl-N-vinyl propionic amide, N-vinyl butyric amide, N-methyl-N-vinyl butyric amide, N- N-vinylbutyric amide, N- Vinylbutyric amide, N-ethyl-N-vinylisobutyric amide, N-propyl-N- Vinyl isobutyryl amide, N-isopropyl-N-vinyl isobutyric amide, N-isopropyl-N-vinyl butyric amide, N-vinyl isobutyric amide, , N-isobutyl-N-vinylisobutyric amide, and the like, or a combination of two or more thereof.

Among them, N-vinyl acetamide and N-vinyl-N-methylacetamide are preferably used.

(2) Amount

The component (d) is added in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the component (a).

This is because if the amount of the component (d) is less than 0.1 parts by weight, the resulting adhesive will have poor compatibility with water and a low cohesive strength, and therefore will have insufficient anti-wet heat and blister resistance In some cases. Further, when the blending amount of the polar vinyl monomer as the component (c) is increased in order to compensate the anti-wet heat whitening property, the relative dielectric constant of the obtained pressure sensitive adhesive easily increases excessively. On the other hand, when the blending amount of the component (d) exceeds 50 parts by weight, the relative dielectric constant of the obtained pressure sensitive adhesive tends to rise excessively, or the cohesive force becomes excessively large and the step following property may become insufficient to be.

Therefore, the lower limit of the amount of the component (d) is more preferably 1 part by weight or more, and more preferably 10 parts by weight or more.

The upper limit of the amount of the component (d) is more preferably 35 parts by weight or less, and still more preferably 25 parts by weight or less.

The blending amount of the component (d) relative to the solventless pressure-sensitive adhesive composition (100% by weight) is not particularly limited so long as it exhibits anti-wet heat whitening while maintaining the relative dielectric constant in a low state, By weight, more preferably at least 0.1% by weight, particularly preferably at least 4.5% by weight, particularly preferably at least 7% by weight.

On the other hand, from the viewpoint of suppressing the relative dielectric constant, the value is preferably 30% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight or less.

The ratio of the polar vinyl monomer as component (c) to the N-vinylacetamide as component (d) (component (c): component (d) (weight ratio)) is in the range of 90:10 to 10:90 Value.

This is because when the blend ratio of the component (d) is less than 10 when the total of the blending ratio of the component (c) and the blending ratio of the component (d) is 100, And the cohesive force is also lowered, so that the anti-wet heat treatment and anti-blistering properties may be insufficient. Further, the blending ratio of the component (c) is increased, and the relative dielectric constant of the obtained pressure sensitive adhesive tends to rise excessively. On the other hand, when the blend ratio of the component (d) exceeds 90, the cohesive force of the resulting pressure sensitive adhesive becomes excessively large, and the step-wise followability may become insufficient.

Therefore, the lower limit value of the compounding ratio of the component (d) is more preferably 20 or more, and more preferably 30 or more.

The upper limit of the compounding ratio of the component (d) is more preferably 80 or less, and more preferably 70 or less.

5. Component (e): urethane (meth) acrylate

The solventless pressure-sensitive adhesive composition of the present invention is characterized by containing urethane (meth) acrylate as the component (e).

The reason for this is that by including urethane (meth) acrylate, a predetermined flexibility can be imparted to the obtained pressure-sensitive adhesive, and further excellent step-following ability can be imparted.

Further, since the non-solvent-type pressure-sensitive adhesive composition acts to increase the viscosity of the pressure-sensitive adhesive composition, it contributes to enhancement of the coating property of the solventless pressure-sensitive adhesive composition and also contributes to thickening of the pressure-sensitive adhesive layer by thickening the coating layer.

(1) Type

Examples of the type of component (e) include, but are not limited to, polyalkylene polyols, polyether polyols, polyester polyols, hydrogenated isoprene having a hydroxyl group terminal, hydrogenated butadiene having a hydroxyl group terminal and the like and a polyisocyanate It is preferable to use a compound obtained by modifying a polyurethane oligomer obtained by a (meth) acrylic acid derivative.

Among them, it is particularly preferable to use polyether urethane (meth) acrylate.

This is because if the polyether urethane (meth) acrylate is used, the flexibility of the resultant pressure-sensitive adhesive can be further improved owing to the characteristics of the polyether moiety, and furthermore, excellent step traceability can be obtained.

The weight average molecular weight of the component (e) is preferably in the range of 3,000 to 20,000.

This is because when the weight average molecular weight of the component (e) is less than 3,000, the length of the polyether moiety or the like which contributes to the improvement of the flexibility is excessively shortened, and it becomes difficult to obtain excellent step traceability to be. On the other hand, when the weight average molecular weight of the component (e) exceeds 20,000, the viscosity of the solventless pressure-sensitive adhesive composition tends to excessively increase, and it may become difficult to obtain a satisfactory coating property.

Therefore, the lower limit value of the weight average molecular weight of component (e) is more preferably 4000 or more, and more preferably 7000 or more.

The upper limit of the weight average molecular weight of the component (e) is more preferably 17000 or less, and more preferably 13000 or less.

(2) Amount

Further, the blending amount of the component (e) is set to a value within a range of 10 to 200 parts by weight based on 100 parts by weight of the component (a).

This is because if the blending amount of the component (e) is less than 10 parts by weight, it becomes difficult to impart sufficient flexibility to the obtained pressure-sensitive adhesive, and the step-wise followability may become insufficient. On the other hand, when the blending amount of the component (e) exceeds 200 parts by weight, the viscosity of the solventless pressure-sensitive adhesive composition tends to excessively increase, and it may become difficult to obtain a satisfactory coating property.

Therefore, the lower limit of the amount of the component (e) is more preferably 40 parts by weight or more, and still more preferably 60 parts by weight or more.

The upper limit of the amount of the component (e) is more preferably 130 parts by weight or less, and more preferably 90 parts by weight or less.

6. Component (f): Photopolymerization initiator

The solventless pressure-sensitive adhesive composition of the present invention preferably contains a photopolymerization initiator as the component (f).

This is because the inclusion of a photopolymerization initiator not only makes it possible to constitute the pressure-sensitive adhesive composition of the present invention more easily as a solventless pressure-sensitive adhesive composition but also eliminates the need to apply heat to cure the pressureless pressure- Heat deterioration of the base material or the like as well as heat shrinkage can be prevented.

This is because the volatile component in the pressure-sensitive adhesive composition without solvent can be cured without loss by heating.

(1) Type

Examples of the component (f) include, but are not limited to, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl Hydroxy-2-methyl-1-phenylpropane, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy- 1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- ) Phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, , 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, Benzyl dimethyl ketal, acetophenone Methyl ketal, p-dimethylaminobenzoic acid ester, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl- Pin oxide, and the like, or a combination of two or more.

In the case of using a thermal polymerization initiator, for example, persulfates such as potassium persulfate and ammonium persulfate, peroxides such as benzoyl peroxide, lauric peroxide, and azo compounds such as azobisisobutyronitrile are used .

(2) Amount

The blending amount of the component (f) is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the component (a).

This is because if the blending amount of the component (f) is less than 0.1 part by weight, the curing may become insufficient. On the other hand, when the blending amount of the component (f) exceeds 20 parts by weight, an unreacted initiator and decomposition products are excessively contained in the pressure-sensitive adhesive after curing, thereby adversely affecting physical properties.

Therefore, the lower limit value of the blending amount of the component (f) is more preferably 1 part by weight or more, and more preferably 2 parts by weight or more.

The upper limit of the amount of the component (f) is more preferably 10 parts by weight or less, and more preferably 5 parts by weight or less.

7. Component (g): Silane coupling agent

The solventless pressure-sensitive adhesive composition of the present invention preferably contains a silane coupling agent as the component (g).

This is because the inclusion of a silane coupling agent can more effectively improve the tackiness of the obtained pressure-sensitive adhesive.

(1) Type

Examples of the kind of the component (g) include, but are not limited to, vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane , 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane, 3- Methoxysilane, and the like, or a combination of two or more thereof.

(2) Amount

It is preferable that the blending amount of the component (g) is set to a value within a range of 0.01 to 5 parts by weight based on 100 parts by weight of the component (a).

This is because if the amount of the component (g) is less than 0.01 part by weight, the effect of improving the adhesion to an adherend may not be sufficiently obtained. On the other hand, if the blending amount of the component (g) exceeds 5 parts by weight, the blister resistance may easily deteriorate.

Therefore, the lower limit of the amount of the component (g) is more preferably 0.1 part by weight or more, and more preferably 0.3 part by weight or more.

The upper limit of the amount of the component (g) is more preferably 1.5 parts by weight or less, and more preferably 0.8 parts by weight or less.

[Second Embodiment]

A second embodiment of the present invention is a pressure-sensitive adhesive made by photo-curing a solvent-free pressure-sensitive adhesive composition as the first embodiment.

Hereinafter, a pressure-sensitive adhesive according to a second embodiment of the present invention will be specifically described with reference to the drawings.

The pressure-sensitive adhesive sheet according to still another embodiment of the present invention is also described in a form that is included in the description of the pressure-sensitive adhesive of the second embodiment.

The pressure-sensitive adhesive (pressure-sensitive adhesive sheet) of the present invention is preferably produced through the following steps (A) to (C).

(A) preparing a pressure-sensitive adhesive composition of no-solvent-type containing the following components (a) to (e)

  (a) a (meth) acrylic acid ester monomer having an alkyl group having 4 to 20 carbon atoms

                                                              100 parts by weight

  (b) a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton

                                                           1 to 100 parts by weight

  (c) 1 to 60 parts by weight of a polar vinyl monomer

  (d) N-vinylcarboxylic acid amide 0.1 to 50 parts by weight

  (e) 10 to 200 parts by weight of urethane (meth) acrylate

(B) a step of applying a non-solvent-type pressure-sensitive adhesive composition to a substrate to form a coating layer

(C) a step of curing the coating layer to form a pressure-sensitive adhesive

Hereinafter, each process will be described.

1. Process (A): Preparation process of pressureless pressure-sensitive adhesive composition

The step (A) is a step of preparing a solventless pressure-sensitive adhesive composition containing the components (a) to (e).

Such a solvent-free pressure-sensitive adhesive composition is omitted because it has already been described.

2. Process (B): The coating process

The step (B) is a step of applying the solventless pressure-sensitive adhesive composition (1) to the substrate (2) as shown in Fig.

As such a base material, a conventional release film can be used. For example, a polyester film such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, or a polyolefin film such as polypropylene or polyethylene, Or the like may be applied to provide a release layer.

The thickness of such a base material is desirably a value within a range of usually 20 to 150 mu m.

As a method of applying the solventless pressure-sensitive adhesive composition on a substrate, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

The thickness of the coating layer at this time is preferably within a range of 3 to 600 mu m.

3. Process (C): Curing process

The step (C) is a step of curing the coating layer to obtain a pressure-sensitive adhesive.

In such a curing step, when the polymerization initiator in the solventless pressure-sensitive adhesive composition is a thermal polymerization initiator, the coating layer is cured by heating in the range of usually 50 to 150 占 폚. On the other hand, when the polymerization initiator in the solventless pressure-sensitive adhesive composition is a photopolymerization initiator, it is cured by irradiating the coating layer with active energy rays such as ultraviolet rays.

Particularly, it is preferable to cure the coating layer by irradiation with an active energy ray.

This is because, in the case of so-called photo-curing, it is no longer necessary to apply heat to cure the pressure-sensitive adhesive composition without a solvent, and heat deterioration and heat shrinkage of the substrate and the like can be prevented.

When the curing of the coating layer is carried out by irradiation of an active energy ray, as the method of irradiating the active energy ray, as shown in Figs. 1 (b) to 1 (c), the base material 2 and the laminate base material 2 ' As shown in FIG. 2 (b) to FIG. 2 (d), the coating layer 1 sandwiched between the steps It may be a method of conducting a plurality of times of investigation.

(C1) As shown in Fig. 2 (b), the coating layer 1 is irradiated with an active energy ray to preliminarily cure the coating layer 1 to form a pre-cured coated layer 10

(C2) As shown in Fig. 2 (c), a step of laminating the laminate base 2 'to the pre-cured coated layer 10

(C3) As shown in Fig. 2 (d), the pre-cured coated layer 10 in a state in which the laminated base material 2 'is laminated is irradiated with an active energy ray to form the pre-cured coated layer 10 Curing the pressure-sensitive adhesive layer 100 to obtain the pressure-sensitive adhesive layer 100

When the steps (C1) to (C3) are carried out in this way, between the step (C1) and the steps (C2) and (C3), the shrinkage stress in the coating layer, Or give room for resolution.

Therefore, the subsequent lamination process becomes easy, and the reaction can be effectively completed by the final curing while excluding the influence of oxygen by the laminate.

Examples of the active energy ray to be irradiated in the step (C) include ultraviolet rays and electron beams.

The ultraviolet ray can be obtained by a high-pressure mercury lamp, an electrodeless lamp, a xenon lamp or the like, and if it is an electron beam, it can be obtained by an electron beam accelerator or the like.

It is preferable that the accumulated light quantity of the active energy ray irradiated in the step (C) is set to a value within a range of usually 200 to 6,000 mJ / cm 2.

Further, the irradiation of the active energy ray may be performed from the side of the substrate 2, from the side of the laminate base 2 ', or from both sides.

Further, in the above-described method for producing an adhesive, although the description has been given taking the form of a so-called non-carrier in which the pressure-sensitive adhesive layer is sandwiched between two release films such as a base material and a laminate base material, one of the two release films is referred to as a base material You can.

It is also preferable that the thickness of the finally obtained sheet-like pressure-sensitive adhesive is within a range of 3 to 600 占 퐉.

This is because air gaps having various thicknesses can be filled while maintaining the blister resistance.

Therefore, the thickness of the pressure-sensitive adhesive on the sheet is more preferably in the range of 25 to 500 占 퐉, and more preferably in the range of 75 to 300 占 퐉.

An application example in which the pressure sensitive adhesive of the present invention is a thick film is an OCA layer 100 as a thick film in a display device 500 on which a touch panel 200 is mounted as shown in Fig.

Such an application can not only improve the visibility of the display image in the display device 500 by easily charging the conventional air gap but also improve the visibility of the liquid crystal display 300 or the like disposed below the touch panel 200 In order to hide the wiring portion 320, voids can be prevented from being formed by effectively following the projections and depressions by the framed frame printing portion 420 provided on the outer peripheral portion of the lower surface of the cover plate 400. [

4. Characteristics of Adhesive

(1) Total light transmittance

Further, it is preferable that the total light transmittance measured in accordance with JIS K 7361-1: 1997 in a pressure-sensitive adhesive layer having a thickness of 100 mu m made of the pressure-sensitive adhesive of the present invention is 80% or more.

This is because when the total light transmittance is less than 80%, the visibility of the screen may become insufficient when used as OCA.

Therefore, the total light transmittance is more preferably 90% or more, and more preferably 98% or more.

In addition, specific measurement methods of the total light transmittance are described in Examples.

(2) Haze value

The haze value measured in accordance with JIS K 7136: 2000 in the pressure-sensitive adhesive layer before wet heat treatment of the thickness of 200 탆 of the pressure-sensitive adhesive of the present invention is preferably 2% or less, more preferably 1.5% .

The haze value measured in accordance with JIS K 7136: 2000 in the pressure-sensitive adhesive layer after the wet heat durability test of the pressure-sensitive adhesive of the present invention is preferably 25 times or less the haze value before wet heat treatment, More preferably 1.5 times or less.

This is because the haze value before and after the wet heat durability satisfies these conditions to ensure excellent initial transparency and excellent anti-wet heat treatment whiteness, so that it can be stably used as OCA.

The haze value after moist heat durability refers to the haze value when the pressure-sensitive adhesive layer is stored for 24 hours under normal temperature and humidity of 23 ° C and 50% RH after being stored under the moist heat condition of 85 ° C and 85% RH for 120 hours . More specific measurement methods are described in the examples.

(3)

The relative dielectric constant of the pressure-sensitive adhesive of the present invention is preferably set to a value less than 5.5.

This is because, if the relative dielectric constant becomes a value of 5.5 or more, erroneous operation of the touch panel tends to occur when it is used as OCA.

Therefore, it is more preferable to set the relative dielectric constant to a value less than 5.0.

Specific measurement methods of the relative dielectric constant are described in Examples.

(4) Gel fraction

The gel fraction of the pressure-sensitive adhesive of the present invention is preferably set to a value within a range of 40 to 99%.

This is because, when the gel fraction is less than 40%, the pressure-sensitive adhesive layer tends to be excessively deformed or cohesive failure tends to occur. On the other hand, when the gel fraction exceeds 99%, step traceability tends to decrease.

Therefore, the lower limit value of the gel fraction is more preferably 50% or more, and more preferably 60% or more.

The upper limit value of the gel fraction is more preferably 90% or less, and more preferably 80% or less.

(Example)

Hereinafter, the solventless pressure-sensitive adhesive composition or the like of the present invention will be described in more detail with reference to examples.

[Example 1]

1. Preparation of pressure-sensitive adhesive composition

(Meth) acrylic acid ester monomer having an alkyl group of 4 to 20 carbon atoms as a component (a), a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton as a component (b) (meth) acrylate as the component (e), a photopolymerization initiator as the component (f), and a silane coupling agent as the component (g) as the component (c) And the mixture was stirred and then allowed to stand to give a pressure-sensitive adhesive composition without a solvent.

(a) 100 parts by weight of 2-ethylhexyl acrylate

(b) 57.1 parts by weight of isobornyl acrylate

(c) 2-hydroxyethyl acrylate 28.6 parts by weight

(d) N-Vinylacetamide 14.3 parts by weight

(e) 85.7 parts by weight of polyether urethane acrylate

(f) 2-Hydroxy-2-methyl-1-phenyl-propan-1-one 2.9 parts by weight

(g) 3-glycidoxypropyltrimethoxysilane 0.6 part by weight

In the following description, it is assumed that 2-ethylhexyl acrylate is referred to as "2-EHA", isobornyl acrylate as "IBXA", 2-hydroxyethyl acrylate as "2-HEA" Polyether urethane acrylate may sometimes be referred to as " PEUA ".

The polyether urethane acrylate as component (e) was synthesized as follows.

That is, 2 moles of isophorone diisocyanate (IPDI) and 2 mols of 2-hydroxyethyl acrylate (HEA) were charged into 1 mole of polypropylene glycol (PPG) having a weight average molecular weight of 9,200, To obtain a polyether urethane acrylate having a weight average molecular weight of 9,900.

The weight average molecular weight of polypropylene glycol and polyether urethane acrylate is a polystyrene reduced value measured by gel permeation chromatography (GPC) under the following conditions.

GPC measurement apparatus: HLC-8020 manufactured by TOSOH CORPORATION

GPC column: manufactured by TOSO CO., LTD.

   TSK guard column HXL-H

   TSK gel GMHXL (× 2)

   TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

2. Production of adhesive sheet

Next, the obtained non-application-type pressure-sensitive adhesive composition was applied on the release treatment surface of the release sheet to form a coating layer, and then the release treatment surface of the release sheet having different release force was applied to the exposed surface of the application layer.

Next, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 200 占 퐉 was obtained by irradiating a light beam (illuminance: 100 mW / cm 2, cumulative light quantity: 1500 mJ / cm 2) of a high-pressure mercury lamp over the peeling sheet.

The thickness of the pressure-sensitive adhesive layer was measured by a static pressure gauge.

3. Evaluation

(1) Total light transmittance

The total light transmittance of the resulting pressure-sensitive adhesive layer was evaluated.

That is, for the measurement of total light transmittance, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 100 占 퐉 was prepared in the same manner as the pressure-sensitive adhesive sheet having the pressure-

Next, the two release sheets were peeled from the obtained pressure-sensitive adhesive sheet, respectively, and the pressure-sensitive adhesive layer was taken out and used as a measurement sample, and the total light transmittance (%) was measured in accordance with JIS K 7361-1: 1997. The obtained results are shown in Table 2.

(2) wet heat resistance

The resulting adhesive layer was evaluated for anti-wet heat resistance.

Namely, two release sheets were peeled from the resulting pressure-sensitive adhesive sheet to take out a pressure-sensitive adhesive layer having a thickness of 200 mu m, and an acrylic resin plate (acrylic light MR-200, thickness 3 mm) and an alkali- The resultant sample was used as an evaluation sample.

Next, the haze value (%) in the obtained evaluation sample was measured in accordance with JIS K 7136: 2000, and this value was defined as the haze value before wet heat development.

Next, the obtained evaluation sample was stored under the moist heat condition of 85 ° C and 85% RH for 120 hours, and then taken out under normal temperature and normal humidity at 23 ° C and 50% RH.

Next, the haze value immediately after taking out, after 1 hour, after 6 hours, and after 24 hours was measured in the same manner, and this value was regarded as the haze value after moist heat durability. The obtained results are shown in Table 2.

(3)

The relative dielectric constant of the resulting pressure-sensitive adhesive layer was evaluated.

That is, for the measurement of the relative dielectric constant, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 100 占 퐉 was prepared in the same manner as the pressure-sensitive adhesive sheet having the pressure-

Next, two peeling sheets were peeled from the resulting pressure-sensitive adhesive sheet to take out the pressure-sensitive adhesive layer, and an untreated PET film having a thickness of 50 mu m was applied to both surfaces of the pressure-sensitive adhesive layer to obtain evaluation samples.

Next, an electrostatic capacity C1 of an evaluation sample at a frequency of 1 MHz was measured by connecting an Agilent 16451B dielectric test fixture (manufactured by Agilent Technologies) to an impedance / gain / phase analyzer 4194A (manufactured by Hewlett Packard).

The electrostatic capacity C3 (F) of the pressure-sensitive adhesive layer was derived from the following formula (1), assuming that the electrostatic capacity of the untreated PET film having a thickness of 50 占 퐉 is C2 (F).

Further, as the capacitance C3 (F), the thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer d = 100 × 10 ^-6 m, the diameter of the measuring electrodes L = 0.005m, the vacuum dielectric constant ^{_{ε 0 = 8.854 × 10 -12 F}} / m, The relative dielectric constant? _R of the pressure-sensitive adhesive layer was derived from the following equation (2). The obtained results are shown in Table 2.

(4) Gel fraction

The gel fraction of the resulting pressure-sensitive adhesive layer was evaluated.

That is, after the obtained pressure-sensitive adhesive sheet was cut into a size of 80 mm × 80 mm, the two release sheets were each peeled off to obtain a pressure-sensitive adhesive layer having a thickness of 200 μm.

Next, the obtained evaluation sample was wrapped with a mesh made of polyester (mesh size 200), the weight was weighed with a precision balance, and the weight of the mesh alone was subtracted to calculate the weight M1 of the sample for evaluation.

Next, a sample for evaluation in a state of being stacked on the polyester mesh was immersed in ethyl acetate in an environment of 23 ° C for 24 hours, then air-dried for 24 hours under an environment of a temperature of 23 ° C and a relative humidity of 50% RTI ID = 0.0 > 80 C < / RTI > for 12 hours.

Next, a sample for evaluation in a state of being stacked on a polyester mesh was weighed with a precision balance, and then the weight of the mesh alone was subtracted to calculate the weight M2 of the sample for evaluation.

Next, the gel fraction (%) = (M2 / M1) x 100 was calculated. The obtained results are shown in Table 2.

(5) My blistering

The blister resistance of the resulting pressure-sensitive adhesive layer was evaluated.

A polyethylene terephthalate (PET) film (hereinafter referred to as " ITO-PET (polyethylene terephthalate) film ") was prepared by peeling a release sheet from the obtained pressure- ) Was adhered to the exposed surface of the pressure-sensitive adhesive layer and cut to form a laminate (45 mm x 65 mm) of a release sheet / pressure-sensitive adhesive layer / ITO-PET.

Next, the release sheet was peeled off from the obtained laminate of release sheet / pressure-sensitive adhesive layer / ITO-PET, and a polymethyl methacrylate resin (PMMA) plate (hereinafter referred to as " PC -PMMA ") was laminated on the exposed surface of the pressure-sensitive adhesive layer to form a laminate of PC-PMMA / pressure-sensitive adhesive layer / ITO-PET.

Next, the resulting laminate of the PC-PMMA / pressure-sensitive adhesive layer / ITO-PET layer was autoclaved at 50 DEG C and 0.5 MPa for 20 minutes, and then allowed to stand at 85 DEG C and 85% relative humidity for 75 hours did.

Next, the degree of generation of air bubbles between the PC layer and the pressure-sensitive adhesive layer in the laminated product of PC-PMMA / pressure-sensitive adhesive layer / ITO-PET after being left standing was visually confirmed and evaluated according to the following criteria. The obtained results are shown in Table 2.

○: No occurrence of bubbles was confirmed

△: The occurrence of minute bubbles was confirmed

×: occurrence of large bubbles was confirmed

(6) Processability

The tearability of the obtained pressure-sensitive adhesive sheet was evaluated.

That is, when the four sides of the pressure-sensitive adhesive sheet were processed by using a cutting machine, the paste remained on the sides of the blade, the attachment of the paste, and the leaching of the paste on the cross section of the processed pressure- I appreciated. The obtained results are shown in Table 2.

In addition, the evaluation of the workability of the spinning process is an evaluation item concerning the curability of the solventless pressure-sensitive adhesive composition.

○: No residue of grass on the side of the blade, attachment of the grass, and leaching of the paste on the cross section of the adhesive sheet were observed

△: Of the four sides of the adhesive sheet, on the sides 1 and 2, the paste remained on the side of the blade, the paste was attached, and the leaching of the paste on the cross section of the adhesive sheet was confirmed

X: Of the four sides of the pressure-sensitive adhesive sheet, on the sides 3 to 4, a paste remaining on the side surface of the blade, a paste adhesion, and a leaching of the paste on the cross section of the pressure-

[Example 2]

The pressure-sensitive adhesive sheet of Example 2 was prepared in the same manner as in Example 1, except that the blending amount of the component (c) was changed to 14.3 parts by weight and the blending amount of the component (d) was changed to 22.9 parts by weight, Were prepared and evaluated. The obtained results are shown in Table 2.

[Example 3]

In Example 3, a pressure-sensitive adhesive sheet was prepared and evaluated in the same manner as in Example 1, except that the blending amount of the component (d) was changed to 1.4 parts by weight when the solventless pressure-sensitive adhesive composition was prepared. The obtained results are shown in Table 2.

[Comparative Example 1]

In Comparative Example 1, a pressure-sensitive adhesive sheet was prepared and evaluated in the same manner as in Example 1, except that the component (d) was not blended when the solvent-free pressure-sensitive adhesive composition was prepared. The obtained results are shown in Table 2.

[Comparative Example 2]

In Comparative Example 2, a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, except that the blending amount of the component (c) was changed to 57.1 parts by weight and the component (d) was not blended when preparing the solventless pressure- I appreciated. The obtained results are shown in Table 2.

[Table 1]

* Values in parentheses in the column of compounding amount of component (c) indicate the blending ratio of each component when the sum of the blending ratio of component (c) and the blending ratio of component (d) is 100.

[Table 2]

As described above, according to the present invention, it is possible to obtain a copolymer of (meth) acrylic acid ester monomer having a predetermined alkyl group, a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton, a polar vinyl monomer, , And urethane (meth) acrylate at a predetermined ratio, it is possible to stably obtain the basic properties required for the pressure-sensitive adhesive composition without a solvent-form and the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition. In addition, And excellent anti-wet heat-resistance and blister resistance can be obtained.

Therefore, the solvent-free pressure-sensitive adhesive composition or the like of the present invention is expected to significantly contribute to high-quality products in the technical field of touch panels in which a pressure-sensitive adhesive layer having transparency and low dielectric constant is required.

1: Solventless pressure-sensitive adhesive composition (coating layer) 2: Base material
2 ': Laminate substrate 10: Pre-cured coating layer
100: pressure-sensitive adhesive layer (OCA layer) 200: touch panel
300: liquid crystal display 320: wiring part
400: cover plate 420: framed border printing portion
500: display device

Claims (9)

The pressure-sensitive adhesive composition of claim 1, which comprises the following components (a) to (e).
(a) a (meth) acrylic acid ester monomer having an alkyl group having 4 to 20 carbon atoms
100 parts by weight
(b) a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon skeleton
1 to 100 parts by weight
(c) 1 to 60 parts by weight of a polar vinyl monomer
(d) N-vinylcarboxylic acid amide 0.1 to 50 parts by weight
(e) 10 to 200 parts by weight of urethane (meth) acrylate The method according to claim 1,
(C) component (d) (weight ratio)) of the polar vinyl monomer as the component (c) and the N-vinylacetamide as the component (d) in the range of 90:10 to 10:90 Of the pressure-sensitive adhesive composition. The method according to claim 1,
Wherein the polar vinyl monomer as the component (c) is a vinyl monomer having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group and an amide group. The method according to claim 1,
Wherein the N-vinylcarboxylic acid amide as the component (d) is a compound represented by the following general formula (1).

(In the general formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ² represents an alkyl group having 1 to 4 carbon atoms) The method according to claim 1,
Wherein the weight average molecular weight of the urethane (meth) acrylate as the component (e) is within a range of 3,000 to 20,000. The method according to claim 1,
wherein the photopolymerization initiator as the component (f) is contained in a range of 0.1 to 20 parts by weight based on 100 parts by weight of the component (a). The method according to claim 1,
wherein the silane coupling agent as the component (g) is contained in a range of 0.01 to 5 parts by weight based on 100 parts by weight of the component (a). A pressure-sensitive adhesive obtained by photo-curing the pressure-sensitive adhesive composition of claim 1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 8 on a substrate.

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