KR20180111474A - Adhesive composition, adhesive, adhesive sheet and display - Google Patents

Abstract

An object of the present invention is to provide an adhesive composition, an adhesive, an adhesive sheet and a display which are excellent in the stepped followability, blister resistance, and anti-wet heat resistance and which can suppress the dielectric constant to a low level. In order to achieve the object, the provided adhesive composition comprises: a (meth)acrylic acid ester polymer (A) comprising an N-vinylcarboxylic acid amide as a monomer unit forming the polymer; active energy ray-curable component (C); and preferably a crosslinking agent (B).

Description

[0001] ADHESIVE COMPOSITION, ADHESIVE, ADHESIVE SHEET AND DISPLAY [0002]

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet suitable for use in a display (display), and a display body obtained by using them.

2. Description of the Related Art Various mobile electronic devices such as smart phones and tablet terminals in recent years are equipped with a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) The number of cases where the display is a touch panel is also increasing.

In the above-described display, a protective panel is usually provided on the surface side of the display module. Along with the reduction in thickness and weight of electronic devices, the protective panel has been changed from a conventional glass plate to a plastic plate such as an acrylic plate or a polycarbonate plate.

Here, a gap is provided between the protective panel and the display body module so that the deformed protective panel does not hit the display body module even when the protective panel is deformed by an external force.

However, when such air gaps are present, there is a problem that the reflection loss of light due to the difference in refractive index between the protective panel and the air layer and the refractive index difference between the air layer and the display module is large, .

Thus, it has been proposed to improve the image quality of the display by filling the space between the protective panel and the display module with the pressure-sensitive adhesive layer. However, on the side of the display body module of the protective panel, the printed layer on the framed frame may exist as a step. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer is excited near the step, thereby causing reflection loss of light. Therefore, the above-mentioned pressure-sensitive adhesive layer is required to follow step difference.

In order to solve the above problems, Patent Document 1 discloses a pressure-sensitive adhesive layer that fills the gap between a protective panel and a display module, and has a shear storage modulus (G ') at 25 ° C and 1 Hz of 1.0 × 10 ⁵ Pa or less , And a pressure-sensitive adhesive layer having a gel fraction of 40% or more.

Japanese Patent Laid-Open No. 2010-97070

In Patent Document 1, the storage elastic modulus at room temperature is lowered in the pressure-sensitive adhesive layer so as to improve the step-wise followability. However, if the storage elastic modulus at room temperature is made to be as low as described above, the storage elastic modulus at high temperature drops more than necessary, and a problem occurs under the durability condition. For example, when high-temperature and high-humidity conditions are applied, bubbles are generated in the vicinity of the stepped portion, out gas is generated from the plastic plate serving as a protective panel, and blisters such as bubbles, lifting and peeling occur. On the other hand, if the pressure-sensitive adhesive layer is made hard to improve the blister resistance, the step-wise followability deteriorates.

Further, in the conventional pressure-sensitive adhesive layer, there is a case where the pressure-sensitive adhesive layer becomes white when the pressure is returned to room temperature and normal after high-temperature and high-humidity (wet heat) conditions are performed. In order to improve the anti-wet heat resistance of the pressure-sensitive adhesive, as a constituent monomer of an acrylic polymer which is a subject polymer, there is a method of using a hydroxyl group-containing monomer in an amount exceeding the amount contributing to crosslinking. However, in this case, due to the high polarity of the hydroxyl group-containing monomer-derived component, the dielectric constant of the resulting pressure-sensitive adhesive increases, which may cause malfunction of the touch panel or decrease responsiveness.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a display body which are excellent in step- The purpose is to provide.

In order to achieve the above object, first, the present invention provides a method for producing a polymer, comprising (meth) acrylic acid ester polymer (A) comprising N-vinylcarboxylic acid amide and an active energy ray- (Invention 1). ≪ tb > < TABLE >

After adhering two adherends with a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to the invention (Invention 1), the pressure-sensitive adhesive layer is cured by irradiating the pressure-sensitive adhesive layer with an active energy ray to form a pressure-sensitive adhesive layer after curing . In this pressure-sensitive adhesive layer after curing, the film strength is improved by curing. Further, since the N-vinylcarboxylic acid amide is copolymerized in the (meth) acrylic acid ester polymer (A), the obtained pressure sensitive adhesive has a high adhesive force and a high cohesive force. By virtue of these synergistic effects, the pressure-sensitive adhesive layer after curing exhibits excellent blister resistance. Further, the presence of the carboxylic acid amide, which is an excellent hydrophilic group, in the pressure-sensitive adhesive suppresses the whitening of the pressure-sensitive adhesive layer after curing, when the pressure-sensitive adhesive layer after being placed under high temperature and high humidity conditions is returned to normal temperature and normal humidity. Further, since the N-vinylcarboxylic acid amide has a low polarity, the resulting adhesive does not improve the dielectric constant while improving the anti-wet heat resistance. Further, the cured pressure-sensitive adhesive layer containing the cured product of the active energy ray-curable component (C) tends to have a lower dielectric constant than the pressure-sensitive adhesive layer not containing the cured product. For these reasons, the pressure-sensitive adhesive layer after curing is suppressed to have a low dielectric constant.

In the above invention (Invention 1), it is preferable that the (meth) acrylic acid ester polymer (A) comprises a monomer having a reactive functional group having a reactive functional group in the molecule as a monomer unit constituting the polymer, (B) (Invention 2).

In the above invention (Invention 2), the mass ratio of the reactive functional group-containing monomer as the monomer unit constituting the polymer to the N-vinylcarboxylic acid amide in the (meth) acrylic acid ester polymer (A) 5 to 50: 50 (invention 3).

In the above invention (invention 2 or 3), it is preferable that the (meth) acrylic acid ester polymer (A) contains 5 mass% or more and 30 mass% or less of the monomer having a reactive functional group as a monomer unit constituting the polymer (Invention 4).

Secondly, the present invention relates to a polymer having a crosslinked structure composed of a (meth) acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer and a crosslinking agent (B) The present invention provides an active energy ray-curable pressure-sensitive adhesive comprising the component (C) (Invention 5).

The pressure sensitive adhesive according to the invention (invention 5) preferably has a gel fraction of 30% or more and 90% or less (invention 6).

In the above invention (Invention 5 or 6), in the case of a laminate comprising a pressure-sensitive adhesive layer having a thickness of 50 μm and a pressure-sensitive adhesive layer sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm, the pressure- The laminate was subjected to a durability test in which the laminate was stored under the moist heat condition of 85 ° C and 85% RH for 120 hours. Next, the laminate was stored for 24 hours in normal temperature and normal humidity at 23 ° C and 50% RH The haze value obtained by subtracting the haze value before the durability test is preferably less than 5 points (invention 7).

Thirdly, the present invention provides a pressure-sensitive adhesive sheet comprising two release sheets and a pressure-sensitive adhesive layer sandwiched between the release sheets so as to contact the release surfaces of the two release sheets, wherein the pressure- 7) (invention 8).

Fourthly, the present invention provides a display body comprising one display body constituting member, another display body constituting member, and a post-curing pressure-sensitive adhesive layer for bonding the one display body constituting member and the other display body constituting member to each other, Wherein at least one of the one display body constituting member and the other display body constituting member is made of a plastic plate and the pressure sensitive adhesive layer after curing is a (meth) acrylic resin containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, There is provided a display body comprising a pressure-sensitive adhesive comprising a crosslinked structure composed of an acrylic acid ester polymer (A) and a crosslinking agent (B) and containing a cured product of the active energy ray-curable component (C) 9).

Fifthly, the present invention is a laminate having a cured pressure-sensitive adhesive layer formed by curing a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (invention 8) sandwiched between a glass plate and a plastic plate, Wherein the increase in haze value obtained by subtracting the haze value before the durability test from the haze value when the durability test is performed and the sample is stored in normal temperature and normal humidity at 23 占 폚 and 50% RH for 24 hours is less than 5 points. Provide sieve.

According to the adhesive composition, the pressure-sensitive adhesive, the pressure-sensitive adhesive sheet and the display according to the present invention, the step-following property, the blister resistance and the anti-wet heat resistance can be both excellent and the dielectric constant can be suppressed to a low level.

1 is a sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention;
2 is a sectional view of a display body according to an embodiment of the present invention;

Hereinafter, an embodiment of the present invention will be described.

[Adhesive composition]

(Hereinafter may be referred to as " sticky composition P ") according to the present embodiment is a polymer obtained by copolymerizing (meth) acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide And contains an energy ray curable component (C). The (meth) acrylic acid ester polymer (A) preferably contains a monomer having a reactive functional group having a reactive functional group in the molecule as a monomer unit constituting the polymer, and the adhesive composition P is preferably a . In the present specification, the term "(meth) acrylic acid" means both of acrylic acid and methacrylic acid. The same is true of other similar terms. The term " polymer " also includes the concept of " copolymer ".

The pressure-sensitive adhesive layer obtained by crosslinking (crosslinking) the pressure-sensitive adhesive composition P according to the present embodiment has not yet been cured by the active energy ray at the stage of the pressure-sensitive adhesive sheet, that is, before being adhered to the adherend, Therefore, it is possible to alleviate the stress generated when an object to be adhered to an adherend such as a display body constituting member is struck. Therefore, even when the pressure sensitive adhesive sheet is stuck to the display body constituting member having a step difference, the pressure sensitive adhesive layer is easy to follow the step, and occurrence of gaps, lifting, etc. in the vicinity of the step is suppressed.

 When the pressure-sensitive adhesive sheet is used, one pressure-sensitive adhesive layer is used to apply pressure to the pressure-sensitive adhesive layer through one pressure-sensitive adhesive layer, Investigate active energy lines. As a result, the active energy ray-curable component (C) is cured and the pressure-sensitive adhesive layer becomes a pressure-sensitive adhesive layer after curing. Since the pressure-sensitive adhesive layer after curing has improved film strength by curing, even when the obtained laminate (display body) is left under high temperature and high humidity conditions, for example, under the conditions of 85 ° C and 85% RH for 72 hours, Bubbles, lifting, peeling, and the like are prevented from occurring in the vicinity thereof. That is, the post-curing pressure-sensitive adhesive layer obtained by crosslinking and curing the pressure-sensitive adhesive composition P according to the present embodiment has excellent step traceability under high temperature and high humidity conditions.

On the other hand, the pressure-sensitive adhesive obtained from the sticky composition P according to the present embodiment has a high adhesive force and a high cohesive force due to the copolymerization of N-vinylcarboxylic acid amide in the (meth) acrylic acid ester polymer (A). The post-curing pressure-sensitive adhesive layer exhibits excellent blister resistance by a synergistic effect of the pressure-sensitive adhesive having a high adhesive force and a high cohesive force and the film strength being improved by curing. For example, when the above-mentioned laminate (display body) is placed under the conditions of high temperature and high humidity, for example, under the conditions of 85 ° C and 85% RH for 72 hours and out gas is generated from the display body constituting member made of a plastic plate or the like , It is also possible to suppress the occurrence of blisters such as bubbles, entanglement, peeling, etc. at the interface between the pressure-sensitive adhesive layer and the display body constituting member after curing.

Further, the carboxylic acid amide contained in the (meth) acrylic acid ester polymer (A) is an excellent hydrophilic group. When such a hydrophilic group is present in the pressure-sensitive adhesive, even if the pressure-sensitive adhesive layer after curing is placed under high temperature and high humidity conditions, when the moisture penetrating into the pressure-sensitive adhesive layer after curing under the high temperature and high humidity conditions is returned to normal temperature and normal humidity, And as a result, whitening of the pressure-sensitive adhesive layer after curing is suppressed. Therefore, the pressure-sensitive adhesive layer after curing is also excellent in anti-wet heat and whitening property.

Here, in order to improve the anti-wet heat resistance of the pressure-sensitive adhesive, a monomer containing a hydroxyl group having a hydroxyl group in the molecule as a constituent monomer of the (meth) acrylic acid ester polymer (A) is used in a large amount exceeding the amount contributing to crosslinking There is also a method. However, in this case, the dielectric constant of the obtained pressure sensitive adhesive increases due to the high polarity of the hydroxyl group-containing monomer-derived component. On the other hand, since the N-vinylcarboxylic acid amide has a low polarity, the resulting adhesive does not improve the dielectric constant while improving the anti-wet heat resistance. Further, the cured pressure-sensitive adhesive layer containing the cured product of the active energy ray-curable component (C) tends to have a lower dielectric constant than the pressure-sensitive adhesive layer not containing the cured product. For these reasons, the pressure-sensitive adhesive layer after curing is suppressed to have a low dielectric constant. Therefore, the malfunction of the touch panel due to the dielectric constant of the pressure-sensitive adhesive layer after curing can be effectively suppressed, and the responsiveness of the touch panel can be improved.

1. Each component

(1) The (meth) acrylic acid ester polymer (A)

The (meth) acrylic acid ester polymer (A) in the present embodiment contains N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, preferably a (meth) acrylic acid alkyl ester, And a reactive functional group-containing monomer having a functional group.

The pressure-sensitive adhesive obtained by (meth) acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer is excellent in both blister resistance and anti-wet heat resistance The dielectric constant is suppressed to a low level.

Examples of the N-vinylcarboxylic acid amide include N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl- Formamide, N-vinyl-N-ethylacetamide, N-methyl-N-vinylformamide and N-methyl-N-vinylacetamide. Among the above, N-vinylacetamide is preferable from the viewpoints of blister resistance, anti-wet heat resistance and dielectric constant. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains 0.5% by mass or more of N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, particularly preferably contains 1% by mass or more, % Or more. The (meth) acrylic acid ester polymer (A) preferably contains 15 mass% or less of N-vinylcarboxylic acid amide as the monomer unit constituting the polymer, particularly preferably 10 mass% or less, More preferably 8% by mass or less. When the (meth) acrylic acid ester polymer (A) contains N-vinylcarboxylic acid amide in the amount as the monomer unit in the above-mentioned amount, the blister resistance and wet heat resistance whitening property in the cured pressure- The dielectric constant of the pressure-sensitive adhesive, that is, the pressure-sensitive adhesive layer after curing is effectively suppressed to be low.

The (meth) acrylic acid ester polymer (A) in the present embodiment preferably contains a (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer, and thereby can exhibit good tackiness . The alkyl group may be linear or branched or may have a cyclic structure.

As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is preferable from the viewpoint of adhesiveness. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl Stearyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and adamantyl (meth) acrylate. These may be used alone or in combination of two or more.

As the (meth) acrylic acid alkyl ester, among the above, a (meth) acrylic acid alkyl ester in which the alkyl group has 5 to 20 carbon atoms is preferable. The (meth) acrylic acid alkyl ester having a large number of carbon atoms has high hydrophobicity and can lower the dielectric constant of the resulting pressure-sensitive adhesive. Examples of the (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group include 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate and the like. 2-ethylhexyl methacrylate is particularly preferable.

The (meth) acrylic acid ester polymer (A) preferably contains 40 mass% or more of (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer, more preferably 50 mass% or more, By mass or more, particularly preferably 65% by mass or more. When the (meth) acrylic acid alkyl ester is contained in an amount of 40 mass% or more, the (meth) acrylic acid ester polymer (A) can exhibit favorable tackiness. The (meth) acrylic acid ester polymer (A) preferably contains 90 mass% or less of (meth) acrylic acid alkyl ester as the monomer unit constituting the polymer, particularly preferably 85 mass% And more preferably 80 mass% or less. By making the amount of the (meth) acrylic acid alkyl ester 90% by mass or less, it is possible to introduce other monomer components into the (meth) acrylic acid ester polymer (A).

When a (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group is included, the (meth) acrylic acid alkyl ester having a carbon number of 5 to 20 in the alkyl (meth) The content of the alkyl acrylate is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 85% by mass or more. As a result, the dielectric constant of the obtained pressure sensitive adhesive can be effectively lowered. On the other hand, the upper limit of the content of the (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group in the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is not particularly limited, do.

A monomer (hard monomer) having a glass transition temperature (Tg) of 0 占 폚 or more as a homopolymer and a monomer (soft monomer) having a glass transition temperature (Tg) of 0 占 폚 or less as a homopolymer may be used as the alkyl (meth) It is also preferable to use them in combination. This is because, by securing tackiness and flexibility by the soft monomer and improving the cohesive force with a hard monomer, it is possible to make the blister resistance and the step traceability better. In this case, the mass ratio of the hard monomer to the soft monomer is preferably 5:95 to 40:60, and particularly preferably 15:85 to 30:70.

The glass transition temperature (Tg) of the hard monomer as the homopolymer is preferably 40 占 폚 or higher, more preferably 60 占 폚 or higher, and even more preferably 80 占 폚 or higher. The glass transition temperature (Tg) is preferably 300 占 폚 or lower, more preferably 200 占 폚 or lower, and even more preferably 130 占 폚 or lower.

Examples of the hard monomer include methyl acrylate (Tg 10 ° C), methyl methacrylate (Tg 105 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C) Adamantyl (Tg 115 ° C), adamantyl methacrylate (Tg 141 ° C), and the like. These may be used alone or in combination of two or more.

Of these hard monomers, methyl acrylate, methyl methacrylate and isobornyl acrylate are preferred from the standpoint of exhibiting the performance of the hard monomer while preventing adverse effects on other properties such as adhesiveness and transparency. From the viewpoint of adhesiveness, methyl acrylate and methyl methacrylate are more preferable.

The glass transition temperature (Tg) of the soft monomer as the homopolymer is preferably -20 占 폚 or lower, more preferably -40 占 폚 or lower, and even more preferably -60 占 폚 or lower. The glass transition temperature (Tg) is preferably -100 DEG C or higher, particularly preferably -90 DEG C or higher, and more preferably -80 DEG C or higher.

As the soft monomer, an alkyl acrylate having a straight chain or branched alkyl group having 2 to 12 carbon atoms is preferably used. For example, 2-ethylhexyl acrylate (Tg-70 캜) and n-butyl acrylate (Tg -54 캜). From the viewpoint of hydrophobicity, 2-ethylhexyl acrylate (Tg -70 캜) Do. These may be used alone or in combination of two or more.

As the (meth) acrylic acid alkyl ester, at least a part of the alkyl (meth) acrylic acid ester is preferably a monomer having an alicyclic structure (an alicyclic structure-containing monomer) as the alkyl group. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the alicyclic structure in the polymer broadens the intervals between the polymers, and the obtained pressure-sensitive adhesive can be made excellent in flexibility. As a result, the pressure sensitive adhesive is more excellent in step following property.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond in a part thereof. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic ring. The alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure) from the viewpoint of making the distance between the obtained (meth) acrylic acid ester polymer (A) appropriate and giving higher stress relaxation property to the pressure- Do. In consideration of the compatibility of the (meth) acrylic acid ester polymer (A) with other components, it is particularly preferable that the polycyclic structure is a bicyclic or tetracyclic ring. In addition, from the viewpoint of imparting stress relaxation property as described above, the number of carbon atoms of the alicyclic structure (the total number of carbon atoms in the part forming the ring, when plural rings are present independently, refers to the total number of carbon atoms) , Usually 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the carbon number of the alicyclic structure is not particularly limited, but from the viewpoint of compatibility as described above, it is preferably 15 or less, and particularly preferably 10 or less.

Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, dicyclo (Meth) acrylate dicyclopentenyloxyethyl (meth) acrylate, and among them, dicyclopentanyl (meth) acrylate (having a carbon number of an alicyclic structure (The number of carbon atoms of the alicyclic structure is 10) or isobornyl (meth) acrylate (the number of carbon atoms of the alicyclic structure is preferably 7), and the isobornyl (meth) acrylate is particularly preferably desirable. These may be used singly or in combination of two or more kinds.

When the (meth) acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a constituent monomer unit, the proportion of the alicyclic structure-containing monomer in the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group, More preferably 1% by mass or more, particularly preferably 5% by mass or more, and more preferably 10% by mass or more. The proportion of the alicyclic structure-containing monomer is preferably 50 mass% or less, particularly preferably 40 mass% or less, and more preferably 30 mass% or less. The excellent adhesion of the obtained pressure-sensitive adhesive to the step and the excellent adhesive force to the transparent conductive film and the plastic are sufficiently exhibited.

The (meth) acrylic acid ester polymer (A) in the present embodiment preferably contains a monomer having a reactive functional group as a monomer unit constituting the polymer. In this case, when the adhesive composition P is crosslinked (thermally crosslinked), the reactive functional group derived from the reactive functional group-containing monomer in the (meth) acrylic acid ester polymer (A) reacts with the reactive functional group of the crosslinking agent (B) A three-dimensional network structure is formed. As a result, the resulting pressure-sensitive adhesive has a higher cohesive force, and is more excellent in step blend resistance under the conditions of blister resistance and high temperature and high humidity.

Examples of the reactive functional group-containing monomer preferably include a monomer having a hydroxyl group in the molecule (a hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (a carboxyl group-containing monomer), a monomer having an amino group in the molecule . Among them, a hydroxyl group-containing monomer having excellent reactivity with the crosslinking agent (B) and having a small adverse effect on the adherend is particularly preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate such as 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable from the viewpoint of reactivity with the crosslinking agent (B) and copolymerization with other monomers. Rxyethyl is particularly preferred. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among them, acrylic acid is preferable in view of reactivity with the crosslinking agent (B) and copolymerization with other monomers. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains 5% by mass or more, more preferably 10% by mass or more, of the monomer having a reactive functional group as a monomer unit constituting the polymer, Or more. The (meth) acrylic acid ester polymer (A) preferably contains 30 mass% or less of the reactive functional group-containing monomer as the monomer unit constituting the polymer, more preferably 28 mass% or less, By mass or less, particularly preferably 20% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a monomer having a reactive functional group in the above amount as a monomer unit, a good crosslinking structure is formed in the resultant pressure-sensitive adhesive, and the pressure- Is obtained. In particular, when the content of the hydroxyl group-containing monomer is 30 mass% or less, the increase of the dielectric constant of the resulting pressure-sensitive adhesive, and further the cured pressure-sensitive adhesive layer, is suppressed by the action of the N-vinylcarboxylic acid amide.

On the other hand, it is also preferable that the (meth) acrylic acid ester polymer (A) does not contain a monomer containing a carboxyl group as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, it is preferable that a transparent substrate such as a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film (Corrosion, change in resistance value, and the like) due to acid can be suppressed even in the presence of an acid.

Here, " not containing a carboxyl group-containing monomer " means that the monomer does not substantially contain a carboxyl group-containing monomer. In addition to not containing a monomer having a carboxyl group at all, Containing monomer to such an extent that corrosion does not occur. Concretely, a monomer containing a carboxyl group-containing monomer in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001% by mass or less, as a monomer unit in the (meth) acrylic acid ester polymer (A) .

The mass ratio of the reactive functional group-containing monomer as the monomer unit constituting the polymer to the N-vinylcarboxylic acid amide in the (meth) acrylic acid ester polymer (A) is preferably 95: 5 to 50:50, more preferably 85: Particularly preferably from 15:60 to 40:40, and even more preferably from 80:20 to 65:35. When the mass ratio is in the above range, blister resistance, anti-wet heat resistance and dielectric constant are balanced.

It is also preferable that the (meth) acrylic acid ester polymer (A) contains a monomer having a nitrogen-containing heterocyclic ring in its molecule as a monomer unit constituting the polymer. The presence of a monomer having a nitrogen-containing heterocyclic ring as a constituent unit in the polymer can impart a predetermined polarity to the pressure-sensitive adhesive, so that the adherend having a certain degree of polarity such as glass can have excellent affinity.

Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N- vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- Acryloylpyridine, N- (meth) acryloylpyrrolidine, N- (meth) acryloyl aziridine, aziridinyl ethyl (meth) acrylate, 2- vinylpyridine, 4- Vinyl pyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide and the like. Of these, N- (meth) acryloylmorpholine exhibiting more excellent adhesion is preferable , N-acryloylmorpholine are particularly preferred. These may be used singly or in combination of two or more kinds.

The (meth) acrylic acid ester polymer (A) preferably contains 0.5% by mass or more of a monomer having a nitrogen-containing heterocyclic ring as a monomer unit constituting the polymer, particularly preferably 1% More preferably at least% by mass. The (meth) acrylic acid ester polymer (A) preferably contains 20 mass% or less of a monomer having a nitrogen-containing heterocyclic ring as a monomer unit constituting the polymer, particularly preferably 15 mass% or less , And more preferably 8 mass% or less. When the content of the monomer having a nitrogen-containing heterocyclic ring is within the above-mentioned range, the obtained pressure-sensitive adhesive can sufficiently exert an excellent adhesive force to glass.

The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As other monomers, monomers that do not contain a reactive functional group are preferable.

Examples of the monomer that does not contain a reactive functional group include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate and styrene. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) is preferably a linear polymer. By virtue of the linear polymer, entanglement of the molecular chains is apt to occur and an improvement in cohesive force can be expected, so that a pressure-sensitive adhesive excellent in blister resistance can be obtained.

The (meth) acrylic acid ester polymer (A) is preferably a solution polymer obtained by a solution polymerization method. As a solution polymer, a polymer having a high molecular weight is easily obtained and an improvement in cohesive force can be expected, so that a pressure-sensitive adhesive excellent in blister resistance can be obtained.

The polymerization of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 or more as the lower limit value, particularly preferably 300,000 or more, more preferably 400,000 or more. If the lower limit of the weight-average molecular weight of the (meth) acrylic acid ester polymer (A) is higher than the above-mentioned range, the resultant pressure-sensitive adhesive has better blister resistance.

The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably not more than 2,000,000, particularly preferably not more than 1.5 million, more preferably not more than 1,000,000. When the upper limit of the weight-average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above value, the resulting pressure sensitive adhesive exhibits better step traceability. In the present specification, the weight average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more kinds.

The content of the (meth) acrylic acid ester polymer (A) in the sticky composition P according to the present embodiment is preferably 50% by mass or more, particularly preferably 60% by mass or more as the lower limit value, more preferably 70% desirable. The lower limit of the content of the (meth) acrylic acid ester polymer (A) makes the adhesive force of the obtained pressure sensitive adhesive better. The upper limit of the content of the (meth) acrylic acid ester polymer (A) is preferably 98% by mass or less, particularly preferably 97% by mass or less, and more preferably 96% by mass or less. The content of the crosslinking agent (B) and the active energy ray-curable component (C) is ensured by the above-mentioned upper limit value of the content of the (meth) acrylic acid ester polymer (A), so that the blister resistance and the step traceability at high temperature and high humidity .

(2) Crosslinking agent (B)

The crosslinking agent (B) crosslinks the (meth) acrylic acid ester polymer (A) by heating the adhesive composition P to form a three-dimensional network structure. As a result, the cohesive force of the obtained pressure sensitive adhesive improves, and the step following property under the conditions of blister resistance and high temperature and high humidity becomes more excellent.

The crosslinking agent (B) is not particularly limited as long as it can react with the reactive functional group possessed by the (meth) acrylic acid ester polymer (A). Examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, Hydrazine type crosslinking agents, aldehyde type crosslinking agents, oxazoline type crosslinking agents, metal alkoxide type crosslinking agents, metal chelate type crosslinking agents, metal salt type crosslinking agents and ammonium salt type crosslinking agents. Among the above, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with a hydroxyl group when the reactive functional group contained in the (meth) acrylic acid ester polymer (A) is a hydroxyl group, When the reactive functional group is a carboxyl group, it is preferable to use an epoxy crosslinking agent having excellent reactivity with a carboxyl group. The crosslinking agent (B) may be used alone or in combination of two or more.

The isocyanate crosslinking agent includes at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di An alicyclic polyisocyanate such as isocyanate and the like, and an adduct which is a reaction product of a burette, isocyanurate and a low molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, And the like. Among them, trimethylolpropane-modified aromatic polyisocyanate, trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferable from the viewpoint of reactivity with a hydroxyl group.

Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylol propane diglycidyl ether, diglycidyl aniline, diglycidyl amine, and the like. Among them, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a carboxy group.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more per 100 parts by mass of the (meth) acrylic acid ester polymer (A) Is more preferable. The content is preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, more preferably 1 part by mass or less. When the content of the cross-linking agent (B) is in the above-mentioned range, the degree of cross-linking becomes appropriate, so that the obtained pressure-sensitive adhesive becomes more resistant to blistering and step traceability under high temperature and high humidity conditions.

(3) Active energy ray-curable component (C)

The pressure-sensitive adhesive obtained by crosslinking (cross-linking) the pressure-sensitive adhesive composition P by the pressure-sensitive adhesive composition P containing the active energy ray-curable component (C) becomes a pressure- This pressure sensitive adhesive is obtained by curing the active energy ray curable component (C) with each other by curing by irradiation with active energy rays after the adherend is attached, and the polymerized active energy ray curable component (C) It is presumed to be entangled with the crosslinked structure (three-dimensional network structure) of A). Such a pressure-sensitive adhesive having a higher-order structure has a high cohesive force and a high film strength, so that it has excellent step traceability and blister resistance under high temperature and high humidity conditions. Further, the cured pressure-sensitive adhesive layer containing the cured product of the active energy ray-curable component (C) tends to have a lower dielectric constant than the pressure-sensitive adhesive layer not containing the cured product. That is, the active energy ray-curable component (C) also contributes to the lowering of the permittivity of the resulting pressure-sensitive adhesive layer after curing.

The active energy ray-curable component (C) is not particularly limited as long as it is cured by irradiation with an active energy ray and is capable of obtaining the above effect, and may be any of monomers, oligomers or polymers, or a mixture thereof. Among them, polyfunctional acrylate-based monomers excellent in compatibility with the (meth) acrylic acid ester polymer (A) and the like are preferable.

Examples of polyfunctional acrylate monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl Di (acryloxyethyl) isocyanurate, allyl cyclohexyl di (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-di (meth) acrylate, Bifunctional types such as bis [4- (2-acryloyloxyethoxy) phenyl] fluorene; (Meth) acrylate such as trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri Trifunctional types such as tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, and? -Caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate; Tetrafunctional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; Pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And hexafunctional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among these, from the viewpoint of step traceability and blister resistance under high temperature and high humidity conditions of the resulting pressure-sensitive adhesive, it is preferable to use di (acryloxyethyl) isocyanurate, tris (acryloxyethyl) isocyanurate,? -Caprolactone- - (2- (meth) acryloxyethyl) isocyanurate and the like are preferable, and a polyfunctional acrylate monomer containing an isocyanurate structure in the molecule is preferable, and trifunctional or more functional isocyanurate isocyanurate Structure is more preferable, and? -Caprolactone-modified tris- (2- (meth) acryloxyethyl) isocyanurate is particularly preferable. These may be used singly or in combination of two or more kinds. From the viewpoint of compatibility with the (meth) acrylic acid ester polymer (A), the polyfunctional acrylate monomer preferably has a molecular weight of less than 1,000.

As the active energy ray-curable component (C), an active energy ray-curable acrylate oligomer may be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, more preferably 1,000 to 50,000, and even more preferably 3,000 to 40,000. These acrylate oligomers may be used singly or in combination of two or more.

As the active energy ray curable component (C), an acryl acrylate polymer having a group having a (meth) acryloyl group introduced into its side chain may also be used. Such an acryl acrylate polymer may be obtained by copolymerizing a (meth) acrylic acid ester with a monomer having a crosslinkable functional group in the molecule and adding a (meth) acryloyl group to a part of the crosslinkable functional group of the copolymer And a compound having a group capable of reacting with a crosslinkable functional group.

The weight average molecular weight of the adduct acrylate-based polymer is preferably from 50,000 to 900,000, and particularly preferably from 100,000 to 500,000.

The active energy ray-curable component (C) may be selected from among the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer and adduct acrylate-based polymer, or a combination of two or more thereof And may be used in combination with other active energy ray curable components.

The content of the active energy ray-curable component (C) in the sticky composition P is preferably from 0.01 to 10 parts by weight, based on the total weight of the (meth) acrylic acid ester polymer ( A) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, as a lower limit value with respect to 100 parts by mass of A). On the other hand, the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, as an upper limit value from the viewpoint of preventing phase separation of the active energy ray-curable component (C) from the (meth) acrylic acid ester polymer And more preferably 10 parts by mass or less, in view of further improving the initial step-following property.

(4) Photopolymerization initiator (D)

When ultraviolet rays are used as an active energy ray used for curing an active energy ray-curable pressure-sensitive adhesive, it is preferable that the pressure-sensitive adhesive composition P further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) in this way, the active energy ray-curable component (C) can be efficiently polymerized, and the polymerization curing time and irradiation amount of the active energy ray can be reduced.

Examples of such a photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethyl 2-methyl-1-phenylpropan-1-one, 1- Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) Hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2- 2-methylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetylthioxanthone, Phenon dimethyl ketal, p-dimethylamino (2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide . These may be used alone or in combination of two or more.

The content of the photopolymerization initiator (D) in the adhesive composition P is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, as a lower limit value with respect to 100 parts by mass of the active energy ray curable component (C). The upper limit value is preferably 30 parts by mass or less, particularly preferably 15 parts by mass or less.

(5) Various additives

The pressure-sensitive adhesive composition P may optionally contain additives such as a silane coupling agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softening agent, a filler, a refractive index adjuster and the like which are commonly used in acrylic pressure- can do. It is also assumed that the polymerization solvent or diluting solvent to be described later is not included in the additive constituting the adhesive composition P.

Here, when the adhesive composition P contains a silane coupling agent, the resulting pressure-sensitive adhesive improves adhesion with the glass member or the plastic plate. As a result, the obtained pressure-sensitive adhesive becomes better in blister resistance.

As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule is preferred because it has good compatibility with the (meth) acrylic acid ester polymer (A) and has optical transparency.

Examples of such a silane coupling agent include a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane , Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercapto (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -methyltrimethoxysilane and the like, Amino group-containing silicon compounds such as 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or a mixture of at least one of these with methyltriethoxysilane, ethyltriethoxy Silane, methyltrimethoxy And condensation products with an alkyl group-containing silicon compound such as silane or ethyltrimethoxysilane. These may be used singly or in combination of two or more kinds.

When the sticky composition P contains a silane coupling agent, the content thereof is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more per 100 parts by mass of the (meth) acrylic acid ester polymer (A) Or more. The content thereof is preferably 2 parts by mass or less, particularly preferably 1 part by mass or less, more preferably 0.5 parts by mass or less.

2. Preparation of adhesive composition

The sticky composition P is obtained by preparing a (meth) acrylic acid ester polymer (A), and subjecting the resulting (meth) acrylic acid ester polymer (A), the active energy ray curable component (C) , A photopolymerization initiator (D), and an additive.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator if desired. As the polymerization solvent, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like may be used.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used in combination. Examples of the azo compound include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane 1-carbonyl Azobis (2,4-dimethyl-4-methoxy valeronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) Azobis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate , t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In the polymerization step, a weight average molecular weight of the obtained polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol.

(C) and, if desired, a crosslinking agent (B) and a photopolymerization initiator (D) are added to a solution of the (meth) acrylic acid ester polymer (A) , An additive, and a diluting solvent are added and sufficiently mixed to obtain a sticky composition P (coating solution) diluted with a solvent. In the case where precipitation occurs when any one of the above components is used in a solid phase or when it is mixed with other components in a non-diluted state, the component is dissolved or diluted in advance in a diluting solvent , And then mixed with other components.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, Propanol and the like; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve Is used.

The concentration and viscosity of the coating solution prepared as described above may be appropriately selected depending on the circumstances without limitation, as long as the coating can be performed within a range that can be coated. For example, it is diluted such that the concentration of the sticky composition P is 10 to 60 mass%. Addition of a diluting solvent is not a necessary condition for obtaining a coating solution, and a diluting solvent may not be added if the viscosity of the adhesive composition P is such as to be a coating. In this case, the adhesive composition P is a coating solution containing a polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

〔adhesive〕

The pressure-sensitive adhesive according to the present embodiment is an active energy ray-curable pressure-sensitive adhesive (pressure-sensitive adhesive before activation energy ray curing) formed by crosslinking (thermally crosslinking) the pressure-sensitive adhesive composition P. The crosslinking of the adhesive composition P can be usually carried out by a heat treatment. This heating treatment may also serve as a drying treatment for volatilizing a diluting solvent or the like from a coating film of the sticky composition P applied to a desired object.

The heating temperature for the heat treatment is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, at 23 DEG C and 50% RH), if necessary. When the curing period is necessary, after the curing period, when the curing period is unnecessary, the pressure-sensitive adhesive is formed after the completion of the heat treatment.

(Meth) acrylic acid ester polymer (A) is sufficiently crosslinked through the crosslinking agent (B) by the above heat treatment (and curing). The pressure-sensitive adhesive thus obtained is excellent in both the step following property and the blister resistance.

The pressure-sensitive adhesive according to the present embodiment preferably has the following properties.

(1) Gel fraction (before active energy ray irradiation)

The gel fraction of the pressure sensitive adhesive (before irradiation with active energy rays) according to the present embodiment is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more as the lower limit value. When the lower limit of the gel fraction of the pressure-sensitive adhesive before irradiation with active energy rays is higher than that of the pressure-sensitive adhesive, the cohesive force of the pressure-sensitive adhesive becomes higher, and thus the blister resistance after curing by irradiation with actinic energy rays and step traceability under high temperature and high humidity conditions are more excellent. The gel fraction of the pressure-sensitive adhesive before irradiation with active energy rays is preferably 90% or less, more preferably 85% or less, and most preferably 80% or less as the upper limit value. If the upper limit of the gel fraction of the pressure-sensitive adhesive before the active energy ray irradiation is above the above value, the pressure-sensitive adhesive is not too hard, and the initial step-wise followability is more excellent. Here, the method of measuring the gel fraction of the pressure-sensitive adhesive (before irradiation with active energy rays) is as shown in the following test examples.

(2) wet heat resistance

The moisture resistance and whitening whiteness of the pressure sensitive adhesive according to the present embodiment can be quantitatively evaluated by the haze value. Specifically, in the case of a laminate comprising a pressure-sensitive adhesive according to the present embodiment and having a thickness of 50 탆 and a pressure-sensitive adhesive layer sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm, the pressure- And then the durability test was carried out on the laminate for 120 hours under the conditions of 85 ° C and 85% RH under a humid condition. Next, haze when stored for 24 hours at room temperature and normal humidity at 23 ° C and 50% RH The haze value increase obtained by subtracting the haze value (%) before the durability test from the value (%) (measured in accordance with JIS K7136: 2000) is preferably less than 5 points, particularly preferably less than 3 points , More preferably less than 1 point. If the increase in the haze value is above, the increase in the haze value is small even after being placed under the moist heat condition, so that whitening of the pressure-sensitive adhesive can be suppressed.

As described above, in the case of a laminate in which a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer after curing) is sandwiched between a glass plate and an acrylic resin plate, the moisture permeated through the acrylic resin plate under the heat- Since it is easy to condense in the laminate, whitening tends to occur in the pressure-sensitive adhesive layer. However, according to the pressure-sensitive adhesive according to the present embodiment, the laminate also exhibits excellent anti-wet heat and whitening properties.

[Adhesive sheet]

The pressure-sensitive adhesive sheet according to the present embodiment is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of the above-described pressure-sensitive adhesive, and is preferably a pressure-sensitive adhesive sheet formed by laminating a release sheet on one side or both sides of the pressure-

Fig. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment.

1, the pressure-sensitive adhesive sheet 1 according to one embodiment is formed by two sheets of release sheets 12a and 12b and two sheets of release sheets 12a and 12b in contact with the release surfaces of the two release sheets 12a and 12b, And a pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. In the present specification, the release surface of the release sheet refers to a surface having release properties in the release sheet, and includes both the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

1. Each member

(1) Pressure-sensitive adhesive layer

The pressure-sensitive adhesive layer 11 is composed of the above-described pressure-sensitive adhesive, that is, the pressure-sensitive adhesive having an active energy ray-curable property which is obtained by crosslinking (thermally crosslinking) the pressure-

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 has a crosslinking structure composed of the (meth) acrylic acid ester polymer (A) and the crosslinking agent (B), and contains the active energy ray-curable component (C) And optionally contains a photopolymerization initiator (D) and an additive.

The thickness of the pressure-sensitive adhesive layer 11 (measured in accordance with JIS K7130) in the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably 10 占 퐉 or more as the lower limit value, more preferably 25 占 퐉 or more, Mu] m or more. If the lower limit of the thickness of the pressure-sensitive adhesive layer 11 is the above-mentioned value, the desired adhesive force is easily exerted, and satisfactory step traceability can be ensured with respect to the normal step of the display body constituting member.

The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 占 퐉 or less, more preferably 600 占 퐉 or less, particularly preferably 300 占 퐉 or less, and most preferably 150 占 퐉 or less. If the upper limit value of the thickness of the pressure-sensitive adhesive layer 11 is above, the anti-wet heat treatment is more excellent and the excellent blistering property is easily exhibited. The pressure-sensitive adhesive layer 11 may be formed as a single layer, or may be formed by laminating a plurality of layers.

(2) Peeling sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 by the use of the pressure-sensitive adhesive sheet 1 and are peeled off when the pressure-sensitive adhesive sheet 1 (pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

Examples of the release sheets 12a and 12b include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, (Meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a poly (ethylene terephthalate) film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, A carbon film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Further, these laminated films may be used.

It is preferable that a peeling treatment is performed on the peeling surface of the peeling sheets 12a and 12b (in particular, the surface in contact with the peeling layer 11). Examples of the releasing agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based releasing agents. It is also preferable that one of the release sheets 12a and 12b is a heavy-duty release sheet having a large stripping force and the other release sheet is a light-leakage release sheet having a small stripping force.

The thickness of the release sheets 12a, 12b is not particularly limited, but is usually about 20 to 150 mu m.

2. Properties

(1) Haze value

The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment preferably has a haze value of 5% or less, more preferably 3% or less, particularly preferably 1% or less, more preferably 0.5% Do. When the haze value of the pressure-sensitive adhesive layer 11 is 5% or less, transparency is extremely high and is suitable as an optical use (for a display). The haze value of the pressure-sensitive adhesive layer does not change even after curing by irradiation with active energy rays. The haze value in this specification is a value measured in accordance with JIS K7136: 2000.

(2) transmission color b *

The transmission color b * defined by the CIE 1976 L * a * b * colorimetric system of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably -2.0 to 2.0, more preferably -1.5 to 1.5 Particularly preferably -1.0 to 1.0. When the transmission color b * of the pressure-sensitive adhesive layer 11 is in the above-mentioned range, the pressure-sensitive adhesive layer 11 becomes less colored and becomes particularly suitable for display. In the present embodiment, it is possible to achieve the above-mentioned transmission color b * by containing a proper amount of N-vinylcarboxylic acid amide as the monomer unit constituting the polymer in the (meth) acrylic acid ester polymer (A). The transmission color b * of the pressure-sensitive adhesive layer does not change even after curing by irradiation with active energy rays. The measurement method of the transmission color b * in the present specification is as shown in the following test example.

(3) Adhesion (after irradiation with active energy rays)

When the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is cured by irradiation of an active energy ray to form a pressure-sensitive adhesive layer after curing, the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet to soda- More preferably 5 N / 25 mm or more, particularly preferably 10 N / 25 mm or more, and more preferably 15 N / 25 mm or more. When the adhesive force of the pressure-sensitive adhesive sheet 1 is 5 N / 25 mm or more, excellent followability of steps under the conditions of blister resistance and high temperature and high humidity is obtained. On the other hand, the upper limit value of the adhesive force is not particularly limited, but is usually preferably 50 N / 25 mm or less, more preferably 45 N / 25 mm or less, and particularly preferably 40 N / 25 mm or less.

Basically, the adhesive force refers to the adhesive force measured by the 180 degree peeling technique according to JIS Z0237: 2009, but the measurement sample is set to have a width of 25 mm and a length of 100 mm, and the measurement sample is attached to an adherend The pressure-sensitive adhesive layer was cured by irradiating with an active energy ray to give a pressure-sensitive adhesive layer after curing. Next, the pressure-sensitive adhesive layer was allowed to stand under the conditions of normal pressure, 23 DEG C and 50% RH for 24 hours, And the speed is measured at 300 mm / min.

3. Production of adhesive sheet

As one production example of the adhesive sheet 1, the application solution of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b) and heat treatment is performed to thermally crosslink the adhesive composition P, After the layer is formed, the peeling surface of the other peeling sheet 12b (or 12a) is superimposed on the coated layer. When the curing period is required, the curing period is set so that the coating layer becomes the pressure-sensitive adhesive layer 11 when the curing period is unnecessary. Thus, the pressure-sensitive adhesive sheet (1) is obtained. The conditions of the heat treatment and curing are as described above.

As another production example of the adhesive sheet 1, a coating solution of the adhesive composition P is applied to the release surface of one release sheet 12a and heat-treated to thermally crosslink the adhesive composition P to form a coating layer , A release sheet 12a with a coating layer is obtained. The application solution of the adhesive composition P is applied to the release surface of the other release sheet 12b and heat-treated to thermally crosslink the adhesive composition P to form a release layer, (12b). Then, the peeling sheet 12a with a coating layer and the peeling sheet 12b with a coating layer are bonded so that both coating layers are in contact with each other. When the curing period is required, the curing period is provided, and when the curing period is unnecessary, the above-mentioned laminated coating layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained. According to this production example, even if the pressure-sensitive adhesive layer 11 is thick, it is possible to manufacture the pressure-sensitive adhesive layer in a stable manner.

As a method of applying the coating solution of the adhesive composition P, 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.

[Display]

As shown in Fig. 2, the display body 2 according to the present embodiment includes a first display body constituting member 21 (one display body constituting member) having at least a step on the side to be conjugated, A pressure-sensitive adhesive layer 11 (a second pressure-sensitive adhesive layer) is disposed between the display body constituting member 22 (another display body constituting member) and the first display body constituting member 21 and the second display body constituting member 22, '). In the display body 2 according to the present embodiment, the first display body constituting member 21 has a step on the surface of the pressure-sensitive adhesive layer 11 'after curing, specifically, .

The cured pressure-sensitive adhesive layer 11 'in the display body 2 is obtained by curing the above-described pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 by energy ray irradiation. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 'after the curing has a crosslinked structure composed of the (meth) acrylic acid ester polymer (A) and the crosslinking agent (B) (D), and an additive, if desired, in addition to the photopolymerization initiator (D). It is presumed that the polymerized energy ray curable component (C) is entangled with a crosslinked structure composed of the (meth) acrylic acid ester polymer (A) and the heat crosslinking agent (B) to form a higher order structure.

The photopolymerization initiator (D) contained in the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (11 ') after the curing has remained without being cleaved by energy ray irradiation, as well as the photopolymerization initiator (D) contained in the pressure- . Therefore, the content thereof is not particularly large and is usually 0.00001 mass% or more and 0.1 mass% or less, preferably 0.0001 mass% or more and 0.01 mass% or less, in the pressure-sensitive adhesive.

The pressure-sensitive adhesive layer 11 '(pressure-sensitive adhesive) of the cured product preferably has the following physical properties.

(1) Gel fraction (after irradiation with active energy rays)

The gel fraction of the pressure-sensitive adhesive layer (11 ') after curing (after irradiation with active energy rays) is preferably 60% or more, particularly preferably 65% or more, more preferably 70% or more. The gel fraction of the pressure-sensitive adhesive in the pressure-sensitive adhesive layer 11 'after curing becomes higher than the gel fraction of the pressure-sensitive adhesive in the pressure-sensitive adhesive layer 11 before curing the active energy ray by curing the active energy ray-curable component (C). When the lower limit of the gel fraction of the pressure sensitive adhesive after irradiation with active energy rays is above the above value, the pressure sensitive adhesive layer 11 'after curing of the display body is more excellent in step following property and blister resistance under high temperature and high humidity conditions.

The gel fraction of the pressure-sensitive adhesive layer (11 ') after curing (after irradiation with active energy rays) is preferably 95% or less, particularly preferably 93% or less, more preferably 90% or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive of the pressure-sensitive adhesive layer 11 'after curing is above the above, it is possible to prevent the pressure-sensitive adhesive layer 11' after curing from deteriorating and the durability being deteriorated. The method for measuring the gel fraction of the pressure-sensitive adhesive (after irradiation with active energy rays) in the pressure-sensitive adhesive layer 11 'after curing is as shown in the following test examples.

(2) Step follow-up rate

The pressure-sensitive adhesive layer 11 'after curing is preferably 15% or more, more preferably 20% or more, particularly preferably 25% or more, of the step difference followability percentage (%) expressed by the following formula % Or more. The upper limit value of the step following rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.

(%) = {(Height of stepped portion (m) maintained in a state of being filled without bubbling, lifting, peeling or the like after predetermined durability test) / (thickness of pressure-sensitive adhesive layer)} x 100

The test method for the step difference followability is as shown in the following test example.

Since the step following rate of the pressure-sensitive adhesive layer 11 'after curing is in the above-mentioned range, the post-curing pressure-sensitive adhesive layer 11' ), So that bubbles, lifting, peeling, and the like are prevented from being generated in the vicinity of the step, thereby suppressing the occurrence of reflection loss of light.

(3) Permittivity

The upper limit of the dielectric constant of the pressure-sensitive adhesive layer (11 ') after curing (after irradiation with active energy rays) at 1.0 MHz is preferably 6.0 or less, more preferably 5.8 or less, and most preferably 5.5 or less. The above upper limit of the dielectric constant can contribute to suppression of malfunction of the touch panel and improvement of responsiveness. Cured pressure-sensitive adhesive layer 11 'formed by using the (meth) acrylic acid ester polymer (A) having the component derived from N-vinylcarboxylic acid amide and the active energy ray-curable component (C) can do.

The lower limit value of the permittivity of the pressure-sensitive adhesive layer 11 'after curing (at the frequency of irradiation of the active energy ray) at 1.0 MHz is not particularly limited, but is usually preferably 3.5 or more, particularly preferably 3.8 or more, More preferably at least 4.0. Since the dielectric constant of the pressure-sensitive adhesive changes before and after irradiation with active energy rays, the permittivity after irradiation with active energy rays becomes important. The measurement method of the dielectric constant of the pressure-sensitive adhesive is as shown in the following test examples.

As the display body 2, for example, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, an electronic paper and the like may be mentioned. The display body 2 may be a member constituting a part of them.

The first display body constituting member 21 is preferably a protective panel made of a laminate or the like including a glass plate, a plastic plate and the like, and is particularly preferably a plastic plate. In this case, the print layer 3 is generally formed on the side of the pressure-sensitive adhesive layer 11 of the first display body constituting member 21 in a framed frame.

The glass plate is not particularly limited and includes, for example, chemically strengthened glass, non-alkali glass, quartz glass, soda lime glass, barium-strontium glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, . The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic resin plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an antiglare layer, or the like) may be provided on one or both sides of the glass plate or the plastic plate, or optical members may be laminated. The transparent conductive film and the metal layer may be patterned.

The second display body constituting member 22 includes an optical member to be attached to the first display body constituting member 21, a display module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) Luminescent (organic EL) module or the like), an optical member as a part of the display body module, or a display body module.

Examples of the optical member include a light-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation film (phase difference film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, A film, and a transparent conductive film. Examples of the shake-prevention film include a hard coat film formed by forming a hard coat layer on one side of a base film.

The material constituting the print layer 3 is not particularly limited, and known materials for printing are used. The thickness of the printing layer 3, that is, the lower limit of the height of the stepped portion is preferably 3 mu m or more, more preferably 5 mu m or more, particularly preferably 7 mu m or more, most preferably 10 mu m or more. With the above-described lower limit value, it is possible to sufficiently secure concealment such as disabling the electric wiring from being visible from the viewer side. The upper limit value is preferably 50 탆 or less, more preferably 35 탆 or less, particularly preferably 25 탆 or less, and more preferably 20 탆 or less. The upper limit value is set as described above, so that the step following property of the pressure-sensitive adhesive layer 11 with respect to the printing layer 3 can be prevented from deteriorating.

In order to manufacture the display body 2, for example, one of the release sheets 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure- To the side of the constituent member 21 on which the print layer 3 is present. At this time, since the pressure sensitive adhesive layer 11 is excellent in the followability of the initial step difference, it is possible to suppress the occurrence of a gap or lifting in the vicinity of the stepped portion by the print layer 3.

Next, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the pressure-sensitive adhesive layer 11 and the second display member constituting member 22, Are laminated to obtain a laminate. As another example, the order of combining the first display body constituent member 21 and the second display body constituent member 22 may be changed.

Thereafter, an active energy ray is irradiated to the pressure-sensitive adhesive layer 11 in the laminate. As a result, the energy ray-curable component (C) in the pressure-sensitive adhesive layer (11) is polymerized and the pressure-sensitive adhesive layer (11) is cured to form the pressure-sensitive adhesive layer (11 '). The irradiation of the energy ray with respect to the pressure-sensitive adhesive layer 11 is usually conducted over either the first display body constituting member 21 or the second display body constituting member 22, and preferably, Is performed over the sieve forming member (21).

Herein, the active energy ray means energy having both energy in the electromagnetic wave or charged particle beam, and specifically, ultraviolet ray, electron beam and the like can be mentioned. Of the active energy rays, ultraviolet rays which are easy to handle are particularly preferable.

The irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW / cm 2. The amount of light is preferably 50 to 10000 mJ / cm 2, more preferably 80 to 5000 mJ / cm 2, and particularly preferably 200 to 2000 mJ / cm 2. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

In the display body 2 described above, since the post-curing pressure-sensitive adhesive layer 11 'is excellent in step traceability even under high temperature and high humidity conditions, the display body 2 is kept under high temperature and high humidity conditions (for example, RH, 72 hours), generation of bubbles, lifting, peeling, and the like in the vicinity of the step is suppressed.

In the display body 2, since the post-curing pressure-sensitive adhesive layer 11 'has excellent blister resistance, when the display body 2 is heated under high temperature and high humidity conditions (for example, 85 ° C, 85% RH, 72 hours), and even when outgas is generated from the first display body constituting member 21 and / or the second display body constituting member 22, the pressure-sensitive adhesive layer 11 'and the display body constituting member 21, and 22 are prevented from generating blisters such as bubbles, lifting, peeling, and the like.

In the display body 2, since the post-curing pressure-sensitive adhesive layer 11 'is excellent in anti-wet heat-releasing property, the display body 2 is kept under high temperature and high humidity conditions (for example, RH, 120 hours) and then returned to room temperature and normal humidity, the pressure-sensitive adhesive layer 11 'is suppressed from being whitened. According to the display body 2 according to the present embodiment, particularly, one of the first display body constituting member 21 and the second display body constituting member 22 is a plastic plate having a thickness of 1 mm or more, and the other is a glass plate , Excellent anti wet heat and whitening properties are exhibited.

Since the dielectric constant of the cured pressure-sensitive adhesive layer 11 'is suppressed to be low, even if the display body 2 is a touch panel, the malfunction of the touch panel due to the dielectric constant of the cured pressure-sensitive adhesive layer 11' And the response of the touch panel is good.

The embodiments described above are described for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

For example, either of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted. The first display body constituting member 21 may have a step difference other than the print layer 3, or may not have a step difference. In addition to the first display body constituting member 21, the second display body constituting member 22 may have a step on the side of the cured pressure-sensitive adhesive layer 11 '.

(Example)

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

1. Preparation of (meth) acrylic acid ester polymer (A)

60 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of 4-acryloylmorpholine, 15 parts by mass of isobornyl acrylate, 5 parts by mass of N-vinylacetamide and 15 parts by mass of 2-hydroxyethyl acrylate were subjected to solution polymerization To obtain a (meth) acrylic acid ester polymer (A). The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by a method described later, and the weight average molecular weight (Mw) was 50,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above Step 1 (solid content conversion value: the same hereinafter) and 0.185 parts by mass of trimethylolpropane-modified tolylene diisocyanate (Toyo Khemsha, product name: BHS8515) , 5 parts by mass of? -Caprolactone-modified tris- (2-acryloxyethyl) isocyanurate as the active energy ray-curable component (C), 5 parts by mass of benzophenone and 1-hydroxy 0.5 parts by mass of a mixture of cyclohexylphenylketone in a mass ratio of 1: 1 and 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name: KBM-403) as a silane coupling agent Were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

Table 1 shows the respective blend (solid content conversion value) of the adhesive composition when the (meth) acrylic acid ester polymer (A) was changed to 100 parts by mass (solid content conversion value). Details of the abbreviations, etc. shown in Table 1 are as follows.

[(Meth) acrylic acid ester polymer (A)]

2EHA: 2-ethylhexyl acrylate

ACMO: 4-acryloylmorpholine

IBXA: isobornyl acrylate

NVA: N-vinylacetamide

HEA: 2-hydroxyethyl acrylate

MMA: methyl methacrylate

BA: n-butyl acrylate

[Crosslinking agent (B)]

TDI: Trimethylolpropane-modified tolylene diisocyanate (Toyo Chemicals Co., Ltd., product name: BHS8515)

Epoxy system: 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane (Mitsubishi Gas Kagakusha Co., Ltd., product name: "TETRAD-C"

3. Production of adhesive sheet

The coating solution of the sticky composition obtained in the above Step 2 was coated on a release treatment surface of a heavy-duty release sheet (LINTEC Corporation, product name " SP-PET752150 ") in which one side of the polyethylene terephthalate film was stripped with a silicone- did. Then, the coating layer was heat-treated at 90 DEG C for 1 minute to form a coating layer.

Next, the coating layer on the heavy-duty release sheet obtained above and a light-weight receding release sheet (LINTEC SHAZE, product name " SP-PET382120 ") in which one side of the polyethylene terephthalate film was stripped with a silicone- Sensitive adhesive layer (thickness: 25 占 퐉) / light-weight receding peel sheet by curing for 7 days under the conditions of 23 占 폚 and 50% RH. A first adhesive sheet was produced.

The coating solution of the adhesive composition obtained in the above Step 2 was applied to the release treatment surface of a heavy-duty release sheet (LINTEC SHAZE, product name " SP-PET752150 ") in which one side of the polyethylene terephthalate film was stripped with a silicone- , And then subjected to a heat treatment at 90 占 폚 for 1 minute to form a coating layer (thickness: 25 占 퐉). Likewise, the coating solution of the sticky composition obtained in the above Step 2 was applied to a release treatment surface of a lightly peelable release sheet (trade name: SP-PET382120) in which one surface of a polyethylene terephthalate film was peeled off with a silicone- , And then subjected to heat treatment at 90 占 폚 for 1 minute to form a coating layer (thickness: 25 占 퐉).

Next, the above heavy-leaved release sheet with a coating layer and the above-obtained light-leaved release sheet with a coating layer obtained as described above were bonded to each other so as to be in contact with each other, The second adhesive sheet having the structure of the heavy-duty releasing sheet / pressure-sensitive adhesive layer (thickness: 50 탆) / light-duty releasing sheet was produced by curing.

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness gauge (trade name: " PG-02 ") according to JIS K7130.

[Examples 2 to 3 and Comparative Examples 1 to 5]

(A), the kind and amount of each monomer constituting the (meth) acrylic acid ester polymer (A), the weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A), the kind and amount of the crosslinking agent (C) and the blending amount of the photopolymerization initiator (D) were changed as shown in Table 1, the first and second adhesive sheets were produced in the same manner as in Example 1.

Here, the weight average molecular weight (Mw) described above is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement Conditions>

GPC measurement apparatus: Tosoh Co., Ltd., HLC-8020

· GPC column (pass in the following order): Dososaje

  TSK guard column HXL-H

  TSK gel GMHXL (× 2)

  TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

[Test Example 1] (Measurement of gel fraction)

The first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 占 퐉) obtained in Examples and Comparative Examples was cut into a size of 80 mm 占 80 mm and the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200) Was weighed with a precision balance and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is defined as M1.

Next, the adhesive wrapped with the polyester-made mesh was immersed in ethyl acetate at room temperature (23 DEG C) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out and air-dried for 24 hours under an environment of a temperature of 23 ° C and a relative humidity of 50%, and further dried in an oven at 80 ° C for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) x100. As a result, the gel fraction (before UV irradiation) of the pressure-sensitive adhesive was derived. The results are shown in Table 2.

On the other hand, the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 占 퐉) obtained in Examples and Comparative Examples was irradiated with ultraviolet light (UV) To give a pressure-sensitive adhesive layer after curing. A gel fraction (after UV irradiation) was derived for the pressure-sensitive adhesive of the pressure-sensitive adhesive layer after the curing in the same manner as described above. The results are shown in Table 2.

<Ultraviolet irradiation condition>

· Using high pressure mercury lamp

Illumination 200 mW / cm 2, light quantity 2000 mJ / cm 2

· UV illuminance · Using UVPF-A1 for light intensity meter

[Test Example 2] (Measurement of haze value)

("NDH-2000" manufactured by Nippon Denshoku Chemical Co., Ltd.) in accordance with JIS K7136: 2000 was applied to the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: Was used to measure the haze value (%). The results are shown in Table 2.

[Test Example 3] (Measurement of transmission color b *) [

The pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 m) obtained in Examples and Comparative Examples was measured for CIE1976 L * using a coincidence light spectrophotometric colorimeter (product name "SQ2000" manufactured by Nippon Denshoku Chemical Co., The transmission color b * defined by the a * b * colorimetric system was measured. The results are shown in Table 2.

[Test Example 4] (Measurement of adhesive force)

The lightly curled release sheet was peeled off from the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 占 퐉) obtained in the examples and the comparative examples and the exposed pressure-sensitive adhesive layer was coated with polyethylene terephthalate (PET) Was laminated on this adhesive layer of a film (Toyobo Co., Ltd., product name &quot; PET A4300 &quot;, thickness: 100 mu m) to obtain a laminate of release sheet / pressure-sensitive adhesive layer / PET film. The resulting laminate was cut into a 25 mm width and a 100 mm length.

Releasing sheet was peeled off from the laminate under an environment of 23 占 폚 and 50% RH, and the exposed pressure-sensitive adhesive layer was attached to soda lime glass (Nihon Itagarasusha), followed by autoclave of Kurihara Seisakusho Co., MPa, at 50 DEG C for 20 minutes. Subsequently, the pressure-sensitive adhesive layer was irradiated with ultraviolet rays (UV) over the PET film under the ultraviolet irradiation conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. The sample having the pressure-sensitive adhesive layer after curing was allowed to stand for 24 hours under the conditions of 23 占 폚 and 50% RH. Then, using a tensile tester (Orientec Corporation, Tensilon) (N / 25 mm after UV irradiation) was measured under the conditions shown in Fig. Conditions other than those described herein were measured in accordance with JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 5] (Evaluation of blister resistance)

The pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 占 퐉) obtained in Examples and Comparative Examples was changed to a polyethylene terephthalate film having a transparent conductive film made of tin-doped indium oxide (ITO) ITO film, thickness: 125 占 퐉) and an acrylic resin plate (Mitsubishi Rayon Co., Ltd., product name "Acrylite MR-200", thickness: 1 mm). Thereafter, the autoclave treatment was carried out for 30 minutes under the conditions of 50 DEG C and 0.5 MPa, and left at normal pressure, 23 DEG C and 50% RH for 24 hours.

The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays under the same conditions as in Test Example 1 over the resin plate to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. Next, the sample was stored under high temperature and high humidity conditions of 85 캜 and 85% RH for 72 hours. Thereafter, the state at the interface between the pressure-sensitive adhesive layer and the adherend after curing was confirmed by naked eyes and the blister resistance was evaluated by the following criteria. The results are shown in Table 2.

○: There were no bubbles, peeling or peeling.

X: Bubbles, peeling, peeling occurred

[Test Example 6] (Measurement of step following rate)

(UV-curable ink, product name: POS-911 Muka) was applied to the surface of a glass plate (NSG Precision Shahe, product name: Corning Glass Eagle XG, length 90 mm x width 50 mm x thickness 0.5 mm) (Outline: 90 mm in length x 50 mm in width and 5 mm in width) so as to be one of 10 占 퐉, 15 占 퐉 and 20 占 퐉. Next, the printed ultraviolet curable ink is cured by irradiating ultraviolet rays (80 W / cm 2, metal halide lamp 2, lamp height 15 cm, belt speed 10 to 15 m / min) : Any one of 10 占 퐉, 15 占 퐉 and 20 占 퐉).

The lightly recyclable release sheet was peeled off from the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 占 퐉) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was laminated on a polyethylene terephthalate (PET) film (Toyobo Co., PET A4300 &quot;, thickness: 100 mu m). Next, the heavy-duty release sheet was peeled off to expose the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer was laminated on each stepped glass plate so that the pressure-sensitive adhesive layer covers the front surface of the frame on the edge of the frame using a laminator (Fuji Plascher, product name "LPD3214"). Thereafter, the autoclave treatment was carried out for 30 minutes under the conditions of 50 DEG C and 0.5 MPa, and left at normal pressure, 23 DEG C and 50% RH for 24 hours.

The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays on the PET film under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. Next, the sample was stored for 72 hours under a high-temperature and high-humidity condition of 85 ° C and 85% RH (endurance test), and then the step traceability was evaluated. The step following property is determined by whether or not the printed step is completely filled by the pressure-sensitive adhesive layer after curing. When bubbles, lifting, peeling, or the like are observed at the interface between the printed step and the cured pressure-sensitive adhesive layer, It can not be done. Here, the step following ability was evaluated as a step following rate (%) expressed by the following equation. The results are shown in Table 2.

(%) = {(Height of stepped portion (m) maintained in a state of being filled without bubbling, lifting, peeling, etc. after durability test) / (thickness of pressure-sensitive adhesive layer after curing)} x 100

[Test Example 7] (Evaluation of wet heat resistance)

The pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 μm) obtained in the Examples and Comparative Examples was laminated on a non-alkali glass plate having a thickness of 1.1 mm and an acrylic resin plate (product name: "ACRYL" Light MR-200 &quot;) to obtain a laminate.

The obtained laminate was subjected to autoclave treatment at 50 캜 under 0.5 MPa for 30 minutes and then left at normal pressure, 23 캜, and 50% RH for 24 hours. Thereafter, the pressure-sensitive adhesive layer of the laminate was irradiated with ultraviolet rays over the acrylic resin plate under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. The haze value (%) of this layered product (sample) was measured in accordance with JIS K7136: 2000 using a haze meter (product name "NDH2000" manufactured by Nippon Denshoku Chemical Co., Ltd.).

Next, the laminate was stored for 120 hours under a moist heat condition of 85 캜 and 85% RH, and then left at normal temperature and normal humidity at 23 캜 and 50% RH for 24 hours. The haze value (%) of this laminate was measured in accordance with JIS K7136: 2000 using a haze meter (product name "NDH2000" manufactured by Nippon Denshoku Chemical Co., Ltd.).

Based on the above-mentioned results, the haze value before the wet heat condition was subtracted from the haze value after the wet heat condition, and the haze value rise (point) after the wet heat condition was calculated. Based on the results, the anti-wet heat whitening performance was evaluated based on the following criteria. The results are shown in Table 2.

◎: Haze value rise less than 1.0 point

○: Increase in haze value is 1.0 or more, less than 5.0 points

×: Haze value increase of 5.0 points or more

[Test Example 8] (Calculation of dielectric constant)

A pressure-sensitive adhesive layer having a thickness of 100 占 퐉 was formed on one side of a polyethylene terephthalate film having a thickness of 50 占 퐉 in the same manner as in the Examples and Comparative Examples. A polyethylene terephthalate film having a thickness of 50 占 퐉 was laminated on the pressure- × 50 mm. Thereafter, ultraviolet rays (UV) were irradiated under the following conditions to harden the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing.

<Ultraviolet irradiation condition>

· Using high pressure mercury lamp

Illumination 200 mW / cm 2, light quantity 1000 mJ / cm 2

· UV illuminance · Using UVPF-A1 for light intensity meter

The electrostatic capacity (C1) of the obtained laminate was measured using an impedance analyzer (Nippon Hewlett Packard Co., Ltd., &quot; HP-4194A &quot;). Further, two polyethylene terephthalate films each having a thickness of 50 占 퐉 were stacked and cut into 50 mm 占 50 mm, and the electrostatic capacity C2 was measured in the same manner. From the values of C1 and C2, the calculation formula of the series connection capacitor

1 / C1 = 1 / C2 + 1 / C3

, The electrostatic capacity C3 of the pressure-sensitive adhesive was calculated. Based on this capacitance C3, the dielectric constant epsilon _s of the pressure-sensitive adhesive was calculated from the following equation. The results are shown in Table 2.

_{ε s = (C3 × d)} / (ε 0 × S)

ε _s : Permittivity of adhesive

ε ₀ : Permittivity of vacuum (8.854 × 10 ^-12 )

C3: Capacitance of the pressure-sensitive adhesive

S: area of the pressure-sensitive adhesive layer after curing

d: thickness of the pressure-sensitive adhesive layer after curing

[Table 1]

[Table 2]

As can be seen from Table 2, the post-curing pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive sheet obtained in the Examples was excellent in blister resistance, stepwise followability and anti-wet heat resistance and exhibited a low dielectric constant .

The adhesive composition, the pressure-sensitive adhesive and the pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding a protective panel made of, for example, a plastic plate to a desired display body constituting member. Further, the display body according to the present invention is suitable as a capacitive touch panel, for example.

1: Pressure sensitive adhesive sheet
11: Pressure-sensitive adhesive layer
12a, 12b: peeling sheet
2:
11 ': Pressure-sensitive adhesive layer after curing
21: first display body constituting member
22: second display body constituting member
3: Printing layer

Claims (9)

(Meth) acrylic acid ester polymer (A) comprising an N-vinylcarboxylic acid amide, and a
Active energy ray-curable component (C)
&Lt; / RTI &gt; The method according to claim 1,
Wherein the (meth) acrylic acid ester polymer (A) contains a reactive functional group-containing monomer having a reactive functional group in the molecule as a monomer unit constituting the polymer,
The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is a pressure-
&Lt; / RTI &gt; 3. The method of claim 2,
The mass ratio of the reactive functional group-containing monomer as the monomer unit constituting the polymer to the N-vinylcarboxylic acid amide in the (meth) acrylic acid ester polymer (A) is 95: 5 to 50:50 Lt; / RTI &gt; The method according to claim 2 or 3,
Wherein the (meth) acrylic acid ester polymer (A) contains 5% by mass or more and 30% by mass or less of the reactive functional group-containing monomer as the monomer unit constituting the polymer. (Meth) acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer and a cross-linking agent (B)
(C) containing an active energy ray-curable component
&Lt; / RTI &gt; wherein the active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive. 6. The method of claim 5,
Wherein the gel fraction is 30% or more and 90% or less. 6. The method of claim 5,
The pressure-sensitive adhesive layer was cured by irradiating an active energy ray to form a pressure-sensitive adhesive layer after curing, and a pressure-sensitive adhesive layer of 50 占 퐉 in thickness made of the pressure-sensitive adhesive was sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm. Was subjected to the durability test under the conditions of 85 ° C and 85% RH for 120 hours and then stored for 24 hours in normal temperature and normal humidity at 23 ° C and 50% RH. The haze value before the durability test Wherein a rise in haze value obtained by subtracting the value is less than 5 points. Two peeling sheets,
And a pressure-sensitive adhesive layer sandwiched between the release sheets so as to contact the release surfaces of the two release sheets,
Wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to any one of claims 5 to 7
Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet. One display body constituting member,
Another display body constituting member,
A pressure-sensitive adhesive layer after the curing of the one display body constituting member and the other display body constituting member
And a display body,
At least one of the one display body constituting member and the other display body constituting member is made of a plastic plate,
Wherein the cured pressure-sensitive adhesive layer has a crosslinked structure composed of a (meth) acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer and a crosslinking agent (B) And a pressure-sensitive adhesive containing a cured product of the curable component (C)
.

Images