KR102447233B1 - Adhesive composition, adhesive, adhesive sheet and display - Google Patents

Abstract

An object of the present invention is to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a display body that are excellent in all of step difference followability, blister resistance, and wet heat whitening resistance, and capable of suppressing the dielectric constant to a low level.
As a means for solving this problem, as a monomer unit constituting the polymer, a (meth)acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide, an active energy ray-curable component (C), and preferably a crosslinking agent (B) provides a pressure-sensitive adhesive composition further containing.

Description

An adhesive composition, an adhesive, an adhesive sheet, and a display body {ADHESIVE COMPOSITION, ADHESIVE, ADHESIVE SHEET AND DISPLAY}

This invention relates to the adhesive composition suitable for use to a display body (display), an adhesive, and an adhesive sheet, and the display body obtained using them.

Various mobile electronic devices such as smartphones 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) element, and the like. There are many cases where the display becomes a touch panel.

In the above displays, the protective panel is normally provided in the surface side of a display body module. The said protection panel is changing from the conventional glass plate to plastic plates, such as an acrylic plate and a polycarbonate plate, with thickness reduction and weight reduction of an electronic device.

Here, between a protection panel and a display body module, even when a protection panel deform|transforms by an external force, the space|gap is provided so that the deformed protection panel may not collide with a display body module.

However, when there is an air gap, that is, the air layer as described above, there is a problem in that the reflection loss of light due to the refractive index difference between the protective panel and the air layer and the refractive index difference between the air layer and the display module is large, and the image quality of the display is deteriorated. .

Then, improving the image quality of a display is proposed by filling in the space|gap between a protection panel and a display body module with an adhesive layer. However, on the display module side of the protection panel, there is a case where the printed layer on the frame border exists as a level difference. If the pressure-sensitive adhesive layer does not follow the level difference, the pressure-sensitive adhesive layer floats near the level difference, thereby causing light reflection loss. Therefore, step difference followability is calculated|required by the above-mentioned adhesive layer.

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

Japanese Patent Laid-Open No. 2010-97070

In patent document 1, it is going to improve step|step difference followability|trackability by making low the storage elastic modulus at the time of the normal temperature in an adhesive layer. However, when the storage elastic modulus at normal temperature is made low as mentioned above, the storage elastic modulus at the time of high temperature will fall more than necessary, and a problem will arise under durable conditions. For example, when high-temperature, high-humidity conditions are implemented, bubbles generate|occur|produce in the step|step difference vicinity, or outgas generate|occur|produces from the plastic plate which is a protection panel, and blisters, such as a bubble, a float, and peeling, generate|occur|produce. On the other hand, when an adhesive layer is made hard in order to improve blister resistance, step|step difference followability|trackability will fall.

Moreover, in the conventional adhesive layer, after implementing high-temperature, high-humidity (moist heat) conditions, when returning to normal temperature and normal humidity, the problem that an adhesive layer whitens may generate|occur|produce. In order to improve the heat-and-moisture whitening resistance of the pressure-sensitive adhesive, as a constituent monomer of the acrylic polymer as the main polymer, there is a method in which a hydroxyl group-containing monomer is used in a large amount in excess of the amount that contributes to crosslinking. However, in this case, the dielectric constant of the adhesive obtained becomes high by the high polarity of the component derived from a hydroxyl-containing monomer, and it originates in it, and a touchscreen may produce malfunction or responsiveness may fall.

The present invention has been made in view of the actual situation as described above, and is excellent in all of step difference followability, blister resistance, and moisture heat and whitening resistance, and is capable of suppressing a low dielectric constant, a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet and a display body intended to provide

In order to achieve the above object, first, the present invention contains, as a monomer unit constituting the polymer, a (meth)acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide, and an active energy ray-curable component (C). It provides a pressure-sensitive adhesive composition, characterized in that (Invention 1).

After bonding two adherends together with the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to the invention (invention 1), the pressure-sensitive adhesive layer is irradiated with active energy rays to cure the pressure-sensitive adhesive layer to form a pressure-sensitive adhesive layer after curing . As for the adhesive layer after this hardening, film strength improves by hardening. Moreover, when N-vinylcarboxylic acid amide is copolymerized with (meth)acrylic acid ester polymer (A), the adhesive obtained will have high adhesive force and high cohesive force. By these synergistic effects, the pressure-sensitive adhesive layer after curing exhibits excellent blister resistance. In addition, since the carboxylic acid amide, which is an excellent hydrophilic group, exists in the pressure-sensitive adhesive, whitening of the pressure-sensitive adhesive layer after curing is suppressed when the pressure-sensitive adhesive layer after curing is returned to normal temperature and humidity after being placed under a high-temperature, high-humidity condition. Further, since N-vinylcarboxylic acid amide has low polarity, while improving the wet-heat whitening resistance of the obtained pressure-sensitive adhesive, it does not improve the dielectric constant. Moreover, compared with the adhesive layer which does not contain the said hardened|cured material, the dielectric constant of the adhesive layer after hardening containing the hardened|cured material of an active energy ray-curable component (C) tends to become low. For these reasons, the dielectric constant of the adhesive layer after hardening is suppressed low.

In the invention (invention 1), the (meth)acrylic acid ester polymer (A) contains a reactive functional group-containing monomer having a reactive functional group in a molecule as a monomer unit constituting the polymer, and the adhesive composition is a crosslinking agent It is preferable to contain (B) (invention 2).

In the invention (invention 2), in the (meth)acrylic acid ester polymer (A), the mass ratio of the reactive functional group-containing monomer as a monomer unit constituting the polymer and the N-vinylcarboxylic acid amide is 95: It is preferable that it is 5-50:50 (Invention 3).

In the above inventions (Inventions 2 and 3), 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 a monomer unit constituting the polymer. preferred (invention 4).

Second, the present invention 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 active energy ray curability Component (C) is provided, the active-energy-ray-curable adhesive characterized by the above-mentioned (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 inventions (inventions 5 and 6), in the laminate in which the 50 µm-thick pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays, After curing as a pressure-sensitive adhesive layer, the laminate was subjected to a durability test for storing for 120 hours under moist heat conditions of 85°C and 85% RH, and then stored for 24 hours at normal temperature and humidity at 23°C and 50% RH. It is preferable that the haze value rise which subtracted the haze value before the said durability test from the haze value at the time is less than 5 points (invention 7).

Thirdly, the present invention includes two release sheets and a pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, wherein the pressure-sensitive adhesive layer includes the pressure-sensitive adhesive (invention 5). To provide a pressure-sensitive adhesive sheet characterized in that consisting of 7) (Invention 8).

Fourth, this invention is a display body provided with one display body structural member, another display body structural member, and the after-hardening adhesive layer which bonds the said one display body structural member and the said other display body structural member together, At least one of said one display body structural member and said other display body structural member consists of a plastic plate, and the said after-hardening adhesive layer contains N-vinylcarboxylic acid amide as a monomer unit which comprises a polymer (meta) It has a crosslinked structure comprised of an acrylic acid ester polymer (A) and a crosslinking agent (B), and consists of an adhesive containing the hardened|cured material of an active energy ray-curable component (C), The display body characterized by the above-mentioned is provided (invention) 9).

Fifthly, the present invention is a laminate having a pressure-sensitive adhesive layer after curing formed by curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (invention 8) sandwiched between a glass plate and a plastic plate, under a wet heat condition of 85 ℃, 85% RH 120 After performing the endurance test for time storage, the haze value increase by subtracting the haze value before the endurance test from the haze value when stored at 23 ° C., 50% RH at room temperature and humidity for 24 hours is less than 5 points. provide a body

According to the pressure-sensitive adhesive composition, the pressure-sensitive adhesive, the pressure-sensitive adhesive sheet, and the display body according to the present invention, it is excellent in all of step followability, blister resistance, and moisture and heat whitening resistance, and can also have a low dielectric constant.

1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.
2 is a cross-sectional view of a display body according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

[Adhesive composition]

The pressure-sensitive adhesive composition according to the present embodiment (hereinafter referred to as "adhesive composition P") is a (meth)acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, and the active Energy ray-curable component (C) is contained. In addition, the (meth)acrylic acid ester polymer (A) preferably contains, as a monomer unit constituting the polymer, a reactive functional group-containing monomer having a reactive functional group in the molecule, and the adhesive composition P includes a crosslinking agent (B) It is preferable to contain In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same is true for other similar terms. In addition, the concept of "copolymer" shall also be included in "polymer".

The pressure-sensitive adhesive layer obtained by crosslinking (thermal crosslinking) of the pressure-sensitive adhesive composition P according to the present embodiment has a relatively low elastic modulus because it has not yet been cured by active energy rays in the step of the pressure-sensitive adhesive sheet, that is, before being stuck to the adherend. For this reason, the stress which arises when bonded with respect to to-be-adhered bodies, such as a display body structural member, can be relieve|moderated. Accordingly, even when the pressure-sensitive adhesive sheet is affixed to a display body structural member having a level difference, the pressure-sensitive adhesive layer tends to follow the level difference, and it is suppressed that a gap, float, etc. occur in the vicinity of the level difference.

In addition, when using the said adhesive sheet, after bonding one display body structural member and another display body structural member with the said adhesive layer, through one display body structural member or another display body structural member, about an adhesive layer. Irradiate an active energy ray. Thereby, an active energy ray-curable component (C) hardens|cures, and an adhesive layer turns into an adhesive layer after hardening. Since the film strength of the pressure-sensitive adhesive layer after curing is improved by curing, even when the obtained laminate (display body) is placed under high temperature and high humidity conditions, for example, under 85°C and 85% RH conditions for 72 hours, the level difference It is suppressed that a bubble, a float, peeling, etc. generate|occur|produce in the vicinity. That is, the pressure-sensitive adhesive layer after curing obtained by crosslinking and curing the pressure-sensitive adhesive composition P according to the present embodiment is excellent in followability to steps under high-temperature, high-humidity conditions.

On the other hand, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P according to the present embodiment has high adhesive strength and high cohesive strength by copolymerizing N-vinylcarboxylic acid amide in the (meth)acrylic acid ester polymer (A). The post-curing pressure-sensitive adhesive layer exhibits excellent blister resistance due to a synergistic effect between the pressure-sensitive adhesive having high adhesive strength and high cohesive strength and the film strength being improved by curing. For example, when the laminate (display body) is placed under high temperature and high humidity conditions, for example, 85° C. and 85% RH for 72 hours, and outgas is generated from a display body constituent member made of a plastic plate or the like Also, it is suppressed that blisters, such as a bubble, a float, and peeling, generate|occur|produce in the interface of an adhesive layer and a display body structural member after hardening.

In addition, the carboxylic acid amide contained in the (meth)acrylic acid ester polymer (A) is an excellent hydrophilic group. If such a hydrophilic group is present in the pressure-sensitive adhesive, even when the pressure-sensitive adhesive layer after curing is placed under high temperature and high humidity conditions, moisture that has penetrated into the pressure-sensitive adhesive layer after curing under the high temperature and high humidity conditions will be released from the pressure-sensitive adhesive layer after curing when returned to normal temperature and humidity. It is estimated that it is easy to fall out, and as a result, whitening of the adhesive layer after hardening is suppressed. Accordingly, the pressure-sensitive adhesive layer after curing is also excellent in heat-and-moisture whitening resistance.

Here, in order to improve the moisture and heat whitening resistance of the pressure-sensitive adhesive, as a constituent monomer of the (meth)acrylic acid ester polymer (A), a hydroxyl group-containing monomer having a hydroxyl group in the molecule is used in a large amount in excess of the amount contributing to crosslinking. There is a way. However, in this case, the dielectric constant of the adhesive obtained will become high by the high polarity of the component derived from a hydroxyl-containing monomer. On the other hand, since N-vinylcarboxylic acid amide has low polarity, while improving the wet-heat whitening resistance of the adhesive obtained, it does not improve the dielectric constant. Moreover, compared with the adhesive layer which does not contain the said hardened|cured material, the dielectric constant of the adhesive layer after hardening containing the hardened|cured material of an active energy ray-curable component (C) tends to become low. For these reasons, the dielectric constant of the adhesive layer after hardening is suppressed low. Therefore, it is possible to effectively suppress the malfunction of the touch panel due to the dielectric constant of the pressure-sensitive adhesive layer after curing, and also to improve the responsiveness of the touch panel.

1. Each ingredient

(1) (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 (meth)acrylic acid alkylester, and reactive in the molecule It further includes a reactive functional group-containing monomer having a functional group.

When the (meth)acrylic acid ester polymer (A) contains N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, the resulting pressure-sensitive adhesive has both blister resistance and wet heat whitening resistance as described above. In addition to being excellent, the dielectric constant is suppressed to be low.

Examples of N-vinylcarboxylic acid amide include N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-methylformamide, and N-vinyl-N-ethyl. Formamide, N-vinyl-N-ethylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide, etc. are mentioned. Among the above, N-vinylacetamide is preferable from the viewpoint of blister resistance, wet heat whitening resistance and dielectric constant. These may be used independently and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 0.5% by mass or more of N-vinylcarboxylic acid amide, particularly preferably 1% by mass or more, and 2% by mass % or more is more preferable. Further, the (meth)acrylic acid ester polymer (A) preferably contains 15% by mass or less of N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, and particularly preferably contains 10% by mass or less, It is more preferable to contain 8 mass % or less. When the (meth)acrylic acid ester polymer (A) contains N-vinylcarboxylic acid amide in the above amount as a monomer unit, in the pressure-sensitive adhesive layer after curing, blister resistance and moisture heat whitening resistance are more excellent, and further obtained The dielectric constant of the pressure-sensitive adhesive and, further, the pressure-sensitive adhesive layer after curing is effectively suppressed low.

It is preferable that the (meth)acrylic acid ester polymer (A) in this embodiment contains (meth)acrylic acid alkylester as a monomer unit which comprises the said polymer, Thereby, favorable adhesiveness can be expressed. . The alkyl group may be linear or branched, and may have a cyclic structure.

As (meth)acrylic-acid alkylester, the C1-C20 (meth)acrylic-acid alkylester of an alkyl group from an adhesive viewpoint is preferable. Examples of the (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid. n-pentyl, (meth)acrylic acid n-hexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid n-decyl, (meth)acrylic acid n-dodecyl, (meth)acrylic acid mi Steel, (meth)acrylic acid palmityl, (meth)acrylic acid stearyl, (meth)acrylic acid cyclohexyl, (meth)acrylic acid isobornyl, (meth)acrylic acid adamantyl, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

As (meth)acrylic-acid alkylester, among the above-mentioned, the (meth)acrylic-acid alkylester whose carbon number of an alkyl group is 5-20 is preferable. As described above, the (meth)acrylic acid alkyl ester having many carbon atoms has high hydrophobicity and can reduce the dielectric constant of the resulting pressure-sensitive adhesive. As the (meth)acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isobornyl (meth)acrylate, etc. are preferable, and have high adhesiveness and hydrophobicity ( Particular preference is given to 2-ethylhexyl meth)acrylic acid.

The (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 40% by mass or more of (meth)acrylic acid alkylester, more preferably 50% by mass or more, and 55% by mass. It is especially preferable to contain % or more, and it is more preferable to contain 65 mass % or more. When the said (meth)acrylic-acid alkylester is contained 40 mass % or more, the (meth)acrylic-acid ester polymer (A) can exhibit suitable adhesiveness. Further, the (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 90% by mass or less of (meth)acrylic acid alkylester, particularly preferably 85% by mass or less, It is more preferable to contain 80 mass % or less. When the said (meth)acrylic-acid alkylester shall be 90 mass % or less, another monomer component can be introduce|transduced in a suitable quantity in a (meth)acrylic-acid ester polymer (A).

Moreover, when C5-C20 (meth)acrylic-acid alkylester of an alkyl group is contained, in the C1-C20 (meth)acrylic-acid alkylester of an alkyl group, the C5-C20 (meth) of the said alkyl group is As a lower limit, as for the content rate of an acrylic acid alkylester, it is preferable that it is 50 mass % or more, It is especially preferable that it is 70 mass % or more, It is more preferable that it is 85 mass % or more. Thereby, the dielectric constant of the adhesive obtained can be reduced effectively. On the other hand, the upper limit of the content rate of the (meth)acrylic acid alkylester whose alkyl group has 5-20 carbon atoms in the C1-C20 (meth)acrylic acid alkylester is not specifically limited, Even if it is 100 mass % do.

As the (meth)acrylic acid alkylester, a monomer (hard monomer) having a glass transition temperature (Tg) of more than 0°C as a homopolymer, and a monomer (soft monomer) having a glass transition temperature (Tg) of 0°C or less as a homopolymer It is also preferable to use them in combination. It is because the blister resistance and step difference tracking property can be made more excellent by improving cohesion force with a hard monomer while ensuring adhesiveness and flexibility with a soft monomer. In this case, it is preferable that it is 5:95-40:60, and, as for mass ratio of a hard monomer and a soft monomer, it is especially preferable that it is 15:85-30:70.

It is preferable that it is 40 degreeC or more, and, as for the glass transition temperature (Tg) of the homopolymer of the said hard monomer, it is especially preferable that it is 60 degreeC or more, It is more preferable that it is 80 degreeC or more. Moreover, it is preferable that it is 300 degrees C or less, and, as for the said glass transition temperature (Tg), it is especially preferable that it is 200 degrees C or less, It is more preferable that it is 130 degrees C or less.

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), acrylic acid and adamantyl (Tg 115°C) and adamantyl methacrylate (Tg 141°C). These may be used independently and may be used in combination of 2 or more type.

Among the hard monomers, methyl acrylate, methyl methacrylate, and isobornyl acrylate are preferable from the viewpoint of further exhibiting the performance of the hard monomer while preventing adverse effects on other properties such as tackiness and transparency. When adhesiveness is also considered, methyl acrylate and methyl methacrylate are more preferable.

The glass transition temperature (Tg) of the soft monomer as a homopolymer is preferably -20°C or lower, particularly preferably -40°C or lower, and more preferably -60°C or lower. Moreover, it is preferable that it is -100 degreeC or more, and, as for the said glass transition temperature (Tg), it is especially preferable that it is -90 degreeC or more, and it is more preferable that it is -80 degreeC or more.

As said soft monomer, the acrylic acid alkylester which has a C2-C12 linear or branched alkyl group is mentioned preferably. Examples include 2-ethylhexyl acrylate (Tg -70°C) and n-butyl acrylate (Tg -54°C), and 2-ethylhexyl acrylate (Tg -70°C) is particularly preferred from the viewpoint of hydrophobicity. do. These may be used independently and may be used in combination of 2 or more type.

Moreover, as said (meth)acrylic-acid alkylester, it is also preferable to make at least one part of the said (meth)acrylic-acid alkylester into the monomer (alicyclic structure containing monomer) which has an alicyclic structure as an alkyl group. Since the alicyclic structure-containing monomer is bulky, by making it exist in a polymer, it is estimated that the space|interval between polymers is widened, and the adhesive obtained can be made into the thing excellent in softness|flexibility. Thereby, the adhesive becomes more excellent in step|step difference followability|trackability.

The carbocyclic ring of the alicyclic structure in an alicyclic structure containing monomer may be a thing of a saturated structure, and may have an unsaturated bond in part. In addition, a monocyclic alicyclic structure may be sufficient as an alicyclic structure, and polycyclic alicyclic structures, such as a bicyclic and tricyclic structure, may be sufficient as it. It is preferable that the said alicyclic structure is a polycyclic alicyclic structure (polycyclic structure) from a viewpoint of making the mutual distance of the obtained (meth)acrylic acid ester polymer (A) appropriate and providing higher stress relaxation property to an adhesive. do. Moreover, it is especially preferable that the said polycyclic structure is bicyclic or tetracyclic in consideration of the compatibility of a (meth)acrylic acid ester polymer (A) and another component. In addition, from the viewpoint of imparting stress relaxation property similarly to the above, the number of carbon atoms in the alicyclic structure (referring to all carbon numbers in the portion forming the ring, and when a plurality of rings are independently present, refers to the total number of carbons) , It is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, although the upper limit in particular of carbon number of an alicyclic structure is not restrict|limited, From a viewpoint of compatibility similarly to the above, it is preferable that it is 15 or less, and it is especially preferable that it is 10 or less.

As said alicyclic structure-containing monomer, specifically, (meth)acrylic acid cyclohexyl, (meth)acrylic acid dicyclopentanyl, (meth)acrylic acid adamantyl, (meth)acrylic acid isobornyl, (meth)acrylic acid dicyclophene tenyl, dicyclopentenyloxyethyl (meth)acrylate, and the like. Among them, dicyclopentanyl (meth)acrylate (the number of carbon atoms in the alicyclic structure), which exhibits more excellent step followability and blister resistance under high-temperature and high-humidity conditions. : 10), (meth) adamantyl acrylate (the number of carbon atoms in the alicyclic structure: 10) or isobornyl (meth) acrylate (the number of carbon atoms in the alicyclic structure: 7) is preferred, and isobornyl (meth) acrylate is particularly desirable. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a constituent monomer unit, the ratio of the alicyclic structure-containing monomer in the (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group is It is preferable that it is 1 mass % or more, It is especially preferable that it is 5 mass % or more, It is more preferable that it is 10 mass % or more. Moreover, it is preferable that it is 50 mass % or less, and, as for the ratio of the said alicyclic structure containing monomer, it is especially preferable that it is 40 mass % or less, It is more preferable that it is 30 mass % or less. While it is more excellent in the step|step difference followability|trackability of the adhesive obtained, the outstanding adhesive force with respect to a transparent conductive film and plastic is fully exhibited.

It is preferable that the (meth)acrylic acid ester polymer (A) in this embodiment contains a reactive functional group containing monomer as a monomer unit which comprises the said polymer. In this case, when the adhesive composition P is crosslinked (thermal 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) to form a crosslinked structure. A three-dimensional network structure is formed. Thereby, the cohesive force of the adhesive obtained becomes high, and it becomes a thing more excellent in blister resistance and step|step difference followability under high temperature, high humidity conditions.

Preferred examples of the reactive functional group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). can Among these, a hydroxyl group-containing monomer which is excellent in reactivity with the crosslinking agent (B) and has little adverse effect on an adherend is particularly preferable.

As the hydroxyl group-containing monomer, for example, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, ( (meth)acrylic acid hydroxyalkyl esters, such as meth)acrylic-acid 3-hydroxybutyl and (meth)acrylic-acid 4-hydroxybutyl, etc. are mentioned. Among them, from the viewpoint of reactivity with the crosslinking agent (B) and copolymerizability with other monomers, (meth)acrylic acid 2-hydroxyethyl and (meth)acrylic acid 4-hydroxybutyl are preferable, and (meth)acrylic acid 2-hydroxyl Roxyethyl is particularly preferred. These may be used independently and may be used in combination of 2 or more type.

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 from the viewpoint of reactivity with the crosslinking agent (B) and copolymerizability with other monomers. These may be used independently and may be used in combination of 2 or more type.

Examples of the amino group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used independently and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 5% by mass or more of a reactive functional group-containing monomer, particularly preferably 10% by mass or more, and 15% by mass or more It is more preferable to contain more. Further, the (meth)acrylic acid ester polymer (A), as a monomer unit constituting the polymer, preferably contains 30% by mass or less of a reactive functional group-containing monomer, more preferably 28% by mass or less, 25 It is especially preferable to contain at most mass %, and it is more preferable to contain 20 mass % or less. When the (meth)acrylic acid ester polymer (A) contains the reactive functional group-containing monomer in the above amount as a monomer unit, a good cross-linked structure is formed in the obtained pressure-sensitive adhesive, and the pressure-sensitive adhesive having better blister resistance and followability to steps under high-temperature and high-humidity conditions is obtained Moreover, especially when content of a hydroxyl-containing monomer is 30 mass % or less, the raise of the dielectric constant of the adhesive obtained by the action|action of N-vinyl carboxylic acid amide, and also the adhesive layer after hardening by extension is suppressed.

On the other hand, it is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit which comprises the said polymer. Since the carboxyl group is an acid component, by not containing a carboxyl group-containing monomer, a defect is caused by acid in the affixed object of the pressure-sensitive adhesive, for example, a transparent conductive film or metal film such as tin-doped indium oxide (ITO). Even in the case where such substances are present, it is possible to suppress their defects (corrosion, resistance value change, etc.) caused by acids.

Here, "does not contain a carboxyl group-containing monomer" means that it does not contain a carboxyl group-containing monomer substantially, and does not contain a carboxyl group-containing monomer at all. It is allowed to contain a carboxyl group-containing monomer to such an extent that corrosion does not occur. Specifically, in the (meth)acrylic acid ester polymer (A), as a monomer unit, a carboxyl group-containing monomer is contained in an amount of 0.1 mass% or less, preferably 0.01 mass% or less, more preferably 0.001 mass% or less. it will allow

In the (meth)acrylic acid ester polymer (A), the mass ratio between the reactive functional group-containing monomer as a monomer unit constituting the polymer and the N-vinylcarboxylic acid amide is preferably 95:5 to 50:50, 85 :15-60:40 is especially preferable, and it is more preferable that it is 80:20-65:35. When the said mass ratio exists in the above-mentioned range, blister resistance, moist heat and whitening resistance, and dielectric constant are achieved with good balance.

Moreover, it is also preferable that the said (meth)acrylic acid ester polymer (A) contains the monomer which has a nitrogen-containing heterocyclic ring in a molecule|numerator as a monomer unit which comprises the said polymer. By providing a monomer having a nitrogen-containing heterocycle as a structural unit in the polymer, a predetermined polarity can be imparted to the pressure-sensitive adhesive, and excellent affinity can be achieved even for an adherend having a certain degree of polarity such as glass.

Examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth) Acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2- Vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. are mentioned, Among them, N-(meth)acryloylmorpholine which exhibits more excellent adhesive force is preferable. , N-acryloylmorpholine is particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A) preferably contains 0.5% by mass or more of a monomer having a nitrogen-containing heterocycle as a monomer unit constituting the polymer, particularly preferably 1% by mass or more, 3 It is more preferable to contain more than mass %. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 20% by mass or less of a monomer having a nitrogen-containing heterocycle as a monomer unit constituting the polymer, and particularly preferably 15% by mass or less. , it is more preferable to contain 8 mass % or less. When content of the monomer which has a nitrogen-containing heterocyclic ring exists in said range, the adhesive force which was obtained can fully exhibit the outstanding adhesive force with respect to glass.

The (meth)acrylic acid ester polymer (A) may contain another monomer as a monomer unit which comprises the said polymer as needed. As another monomer, the monomer which does not contain the functional group which has reactivity is preferable.

Examples of the monomer not containing 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 independently and may be used in combination of 2 or more type.

It is preferable that the (meth)acrylic acid ester polymer (A) is a linear polymer. By being a linear polymer, entanglement of molecular chains becomes easy to occur, and since the improvement of cohesive force can be anticipated, the adhesive which is more excellent in blister resistance is obtained.

Moreover, it is preferable that the (meth)acrylic acid ester polymer (A) is a solution polymer obtained by the solution polymerization method. By being a solution polymer, a high molecular weight polymer becomes easy to be obtained, and since the improvement of cohesive force can be anticipated, the adhesive which is more excellent in blister resistance is obtained.

A random copolymer may be sufficient as the polymerization aspect of a (meth)acrylic acid ester polymer (A), and a block copolymer may be sufficient as it.

As a lower limit, it is preferable that the weight average molecular weight of a (meth)acrylic acid ester polymer (A) is 200,000 or more, It is especially preferable that it is 300,000 or more, It is more preferable that it is 400,000 or more. The blister resistance of the adhesive obtained as the lower limit of the weight average molecular weight of a (meth)acrylic acid ester polymer (A) is more than the said thing becomes more excellent.

Moreover, as for the weight average molecular weight of a (meth)acrylic acid ester polymer (A), it is preferable as an upper limit that it is 2 million or less, It is especially preferable that it is 1.5 million or less, It is more preferable that it is 1 million or less. If the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is below the above, the obtained pressure-sensitive adhesive will be more excellent in followability to steps. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

Moreover, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P according to the present embodiment is, as a lower limit, preferably 50% by mass or more, particularly preferably 60% by mass or more, and more preferably 70% by mass or more desirable. When the lower limit of content of a (meth)acrylic acid ester polymer (A) is the above, the adhesive force of the adhesive obtained becomes more favorable. Moreover, as for content of a (meth)acrylic acid ester polymer (A) as an upper limit, it is preferable that it is 98 mass % or less, It is especially preferable that it is 97 mass % or less, It is more preferable that it is 96 mass % or less. When the upper limit of the content of the (meth)acrylic acid ester polymer (A) is the above, the content of the crosslinking agent (B) and the active energy ray-curable component (C) is secured, and blister resistance and step followability under high temperature and high humidity conditions becomes more excellent.

(2) crosslinking agent (B)

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

As said crosslinking agent (B), what is necessary is just to react with the reactive functional group which the (meth)acrylic acid ester polymer (A) has, For example, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an amine type crosslinking agent, a melamine type crosslinking agent, an aziridine type crosslinking agent, and a hydrazine-based crosslinking agent, an aldehyde-based crosslinking agent, an oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, and an ammonium salt-based crosslinking agent. Among the above, when the reactive functional group of the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with the hydroxyl group, and the (meth)acrylic acid ester polymer (A) has When the reactive functional group is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. Moreover, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more type.

An isocyanate type crosslinking agent contains a polyisocyanate compound at least. As a polyisocyanate compound, For example, aromatic polyisocyanate, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanate, such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di Adducts which are reactants of alicyclic polyisocyanates such as isocyanates and the like, and their biuret forms, isocyanurates, and low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil sieve 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-m-xylylenediamine, Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, etc. are mentioned. Among them, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferable from the viewpoint of reactivity with a carboxyl group.

It is preferable that content of the crosslinking agent (B) in adhesive composition P is 0.01 mass part or more with respect to 100 mass parts of (meth)acrylic acid ester polymer (A), It is especially preferable that it is 0.05 mass part or more, It is 0.1 mass part or more it is more preferable Moreover, it is preferable that the said content is 3 mass parts or less, It is especially preferable that it is 2 mass parts or less, It is more preferable that it is 1 mass part or less. When content of a crosslinking agent (B) exists in an above-mentioned range, the grade of crosslinking becomes a suitable thing, and it becomes the thing more excellent in blister resistance of the adhesive obtained, and step|step difference followable|trackability in high temperature, high humidity conditions.

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

When the pressure-sensitive adhesive composition P contains the active energy ray-curable component (C), the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P (thermal crosslinking) becomes an active energy ray-curable pressure-sensitive adhesive. In this pressure-sensitive adhesive, the active energy ray-curable component (C) is polymerized with each other by curing by active energy ray irradiation after sticking the adherend, and the polymerized active energy ray-curable component (C) is a (meth)acrylic acid ester polymer ( It is presumed to be entangled in the cross-linked structure (three-dimensional network structure) of A). The pressure-sensitive adhesive having such a higher-order structure has a high cohesive force and exhibits high film strength, and therefore is excellent in followability to steps and blister resistance under high-temperature, high-humidity conditions. Moreover, compared with the adhesive layer which does not contain the said hardened|cured material, the dielectric constant of the adhesive layer after hardening containing the hardened|cured material of an active energy ray-curable component (C) tends to become low. That is, the active energy ray-curable component (C) also contributes to low dielectric constant of the obtained post-curing pressure-sensitive adhesive layer.

The active energy ray-curable component (C) is not particularly limited as long as it is a component that is cured by irradiation with an active energy ray and the above-described effect is obtained, and may be any of a monomer, an oligomer or a polymer, or a mixture thereof. Especially, the polyfunctional acrylate type monomer excellent in compatibility with (meth)acrylic acid ester polymer (A) etc. is mentioned preferably.

Examples of the polyfunctional acrylate-based monomer include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. (meth)acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di ( meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyldi(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9- bifunctional types such as bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; Trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane trifunctional types such as tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate; tetrafunctional types such as diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; 5-functional types, such as propionic acid modified dipentaerythritol penta (meth)acrylate; 6 functional types, such as dipentaerythritol hexa(meth)acrylate and caprolactone modified dipentaerythritol hexa(meth)acrylate, etc. are mentioned. Among the above, di(acryloxyethyl)isocyanurate, tris(acryloxyethyl)isocyanurate, ε-caprolactone modified tris A polyfunctional acrylate-based monomer containing an isocyanurate structure in a molecule such as -(2-(meth)acryloxyethyl)isocyanurate is preferable, and is trifunctional or more, and isocyanurate in a molecule A polyfunctional acrylate-based monomer containing a structure is more preferable, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate is particularly preferable. These may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, from a compatible viewpoint with a (meth)acrylic acid ester polymer (A), it is preferable that a polyfunctional acrylate-type monomer has a molecular weight less than 1000.

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

It is preferable that it is 50,000 or less, and, as for the weight average molecular weight of the said acrylate-type oligomer, it is especially preferable that it is 1,000-50,000, It is more preferable that it is 3,000-40,000. These acrylate-type oligomers may be used individually by 1 type, and may be used in combination of 2 or more type.

Moreover, as an active energy ray-curable component (C), the adduct acrylate type polymer in which the group which has a (meth)acryloyl group was introduce|transduced into the side chain can also be used. Such an adduct acrylate-based polymer uses a copolymer of (meth)acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a (meth)acryloyl group in a part of the crosslinkable functional group of the copolymer. and a compound having a crosslinkable functional group and a reactive group.

It is preferable that it is about 50,000-900,000, and, as for the weight average molecular weight of the said adduct acrylate type polymer, it is especially preferable that it is about 100,000-500,000.

The active energy ray-curable component (C) may be used by selecting one type from among the above-mentioned polyfunctional acrylate-based monomers, acrylate-based oligomers, and adduct acrylate-based polymers, or may be used in combination of two or more types. and can also be used in combination with other active energy ray-curable components.

The content of the active energy ray-curable component (C) in the pressure-sensitive adhesive composition P is a (meth)acrylic acid ester polymer ( A) With respect to 100 mass parts, as a lower limit, it is preferable that it is 1 mass part or more, It is more preferable that it is 3 mass parts or more, It is especially preferable that it is 5 mass parts or more. On the other hand, as for the said content, it is preferable that it is 50 mass parts or less as an upper limit from a viewpoint of preventing the active energy ray-curable component (C) from phase-separating a (meth)acrylic acid ester polymer (A), It is more preferable that it is 20 mass parts or less When the viewpoint of further improving the initial stage difference followability is further added, it is particularly preferably 10 parts by mass or less.

(4) Photoinitiator (D)

When using an ultraviolet-ray as an active energy ray used for hardening an active energy ray-curable adhesive, it is preferable that the adhesive composition P contains a photoinitiator (D) further. Thus, by containing a photoinitiator (D), an active energy ray-curable component (C) can be polymerized efficiently, and polymerization hardening time and the irradiation amount of an active energy ray can be decreased.

As such a photoinitiator (D), for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethyl Aminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- Hydroxycyclohexylphenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-( Hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary- Butyl anthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, aceto Phenonedimethylketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl- Phosphine oxide etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

It is preferable that content of the photoinitiator (D) in the adhesive composition P is 0.1 mass part or more as a lower limit with respect to 100 mass parts of active energy ray-curable components (C), It is especially preferable that it is 1 mass part or more. Moreover, as an upper limit, it is preferable that it is 30 mass parts or less, and it is especially preferable that it is 15 mass parts or less.

(5) Various additives

To the pressure-sensitive adhesive composition P, if desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, refractive index modifiers, etc. are added. can do. In addition, the polymerization solvent and dilution solvent mentioned later shall not be contained in the additive which comprises the adhesive composition P.

Here, when the adhesive composition P contains a silane coupling agent, the adhesiveness with a glass member and a plastic plate will improve the adhesive obtained. Thereby, the obtained adhesive becomes a thing more excellent in blister resistance.

As a silane coupling agent, it is an organosilicon compound which has at least 1 alkoxysilyl group in a molecule|numerator, Compatibility with the (meth)acrylic acid ester polymer (A) is good, and what has light transmittance is preferable.

As such a silane coupling agent, for example, polymerizable unsaturated group-containing silicon compounds 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 Mercapto group-containing silicon compounds such as propyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)- An amino group-containing silicon compound such as 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one thereof, and methyltriethoxysilane, ethyltriethoxy Condensates with alkyl-group containing silicon compounds, such as silane, methyl trimethoxysilane, and ethyl trimethoxysilane, etc. are mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the adhesive composition P contains a silane coupling agent, it is preferable that the content is 0.01 mass part or more with respect to 100 mass parts of (meth)acrylic acid ester polymer (A), It is especially preferable that it is 0.05 mass part or more, It is 0.1 mass It is more preferable that it is more than part. Moreover, it is preferable that the said content is 2 mass parts or less, It is especially preferable that it is 1 mass part or less, It is more preferable that it is 0.5 mass parts or less.

2. Preparation of the adhesive composition

The adhesive composition P is a (meth)acrylic acid ester polymer (A) obtained by producing a (meth)acrylic acid ester polymer (A), an active energy ray-curable component (C), and optionally a crosslinking agent (B); It can manufacture by mixing a photoinitiator (D) and an additive.

A (meth)acrylic acid ester polymer (A) can be manufactured by superposing|polymerizing the mixture of the monomer which comprises a polymer by a normal radical polymerization method. It is preferable to perform superposition|polymerization of a (meth)acrylic acid ester polymer (A) by the solution polymerization method using a polymerization initiator as needed. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use 2 or more types together.

As a polymerization initiator, an azo compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonone) Tril), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'- Azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'- azobis[2-(2-imidazolin-2-yl)propane] etc. are mentioned.

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

Moreover, the said polymerization process WHEREIN: By mix|blending a chain transfer agent, such as 2-mercaptoethanol, the weight average molecular weight of the polymer obtained can be adjusted.

When the (meth)acrylic acid ester polymer (A) is obtained, in the solution of the (meth)acrylic acid ester polymer (A), an active energy ray-curable component (C), and optionally a crosslinking agent (B), a photoinitiator (D) , an additive, and a diluting solvent are added, and the adhesive composition P (coating solution) diluted with a solvent is obtained by fully mixing. In any of the above components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component is dissolved or diluted in a dilution solvent alone in advance. After that, you may mix 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, methanol, ethanol, propanol, butanol, 1-methyl Alcohols such as toxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, etc. this is used

The concentration and viscosity of the coating solution prepared in this way may be within a range that can be coated, and is not particularly limited, and may be appropriately selected depending on the situation. For example, it is diluted so that the density|concentration of the adhesive composition P may become 10-60 mass %. Moreover, in obtaining a coating solution, addition of a diluting solvent etc. is not a necessary condition, As long as the adhesive composition P is a coating-able viscosity etc., it is not necessary to add a diluent solvent. In this case, the adhesive composition P turns into a coating solution which uses the polymerization solvent of the (meth)acrylic acid ester polymer (A) as a dilution solvent as it is.

〔adhesive〕

The pressure-sensitive adhesive according to the present embodiment is an active energy ray-curable pressure-sensitive adhesive (adhesive before active energy ray curing) formed by cross-linking (thermal crosslinking) the pressure-sensitive adhesive composition P. Crosslinking of the adhesive composition P can be usually performed by heat treatment. Moreover, this heat processing can also serve as a drying process at the time of volatilizing a dilution solvent etc. from the coating film of the adhesive composition P apply|coated to the desired object.

It is preferable that it is 50-150 degreeC, and, as for the heating temperature of heat processing, it is especially preferable that it is 70-120 degreeC. Moreover, it is preferable that they are 10 second - 10 minutes, and, as for heating time, it is especially preferable that they are 50 seconds - 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at normal temperature (eg, 23°C, 50% RH). When this curing period is required, an adhesive is formed after completion|finish of heat processing, when a curing period is unnecessary, after a curing period passes.

By the above-described heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is sufficiently crosslinked through the crosslinking agent (B). The adhesive obtained in this way is excellent in both step|step difference followability|trackability and blister resistance.

It is preferable that the adhesive which concerns on this embodiment has the following physical properties.

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

As a lower limit, as for the gel fraction of the adhesive (before active energy ray irradiation) which concerns on this embodiment, it is preferable that it is 30 % or more, It is more preferable that it is 40 % or more, It is especially preferable that it is 50 % or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive before irradiation with active energy rays is the above, the cohesive force of the pressure-sensitive adhesive becomes higher, and blister resistance after curing by irradiation with active energy rays and followability to steps under high-temperature, high-humidity conditions are more excellent. Moreover, as for the gel fraction of the adhesive before active energy ray irradiation, as an upper limit, it is preferable that it is 90 % or less, It is especially preferable that it is 85 % or less, It is more preferable that it is 80 % or less. If the upper limit of the gel fraction of the adhesive before irradiation with an active energy ray is the above, the adhesive does not become too hard, but the initial stage difference tracking property becomes more excellent. Here, the measuring method of the gel fraction of an adhesive (before active energy ray irradiation) is as showing in the test example mentioned later.

(2) Moisture and heat whitening resistance

The wet-and-heat whitening resistance of the adhesive which concerns on this embodiment can be quantitatively evaluated by a haze value. Specifically, in a laminate in which an adhesive layer having a thickness of 50 µm made of an adhesive according to the present embodiment is sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm, the adhesive layer is cured by irradiation with an active energy ray to cure the adhesive after curing. After layering, the laminate was subjected to a durability test for 120 hours storage under moist heat conditions of 85° C. and 85% RH, and then, haze when stored for 24 hours at normal temperature and humidity at 23° C. and 50% RH. It is preferable that the haze value increase by subtracting the haze value (%) before the endurance test from the value (%) (value measured in accordance with JIS K7136:2000. The same applies below) is less than 5 points, and particularly preferably less than 3 points , more preferably less than 1 point. It can be said that the raise of a haze value is small that a haze value rise is the above, even after it set|places on wet heat conditions, and whitening of an adhesive is suppressed.

As described above, in a laminate in which an adhesive layer (adhesive layer after curing) is sandwiched between a glass plate and an acrylic resin plate, compared to a laminate in which an adhesive layer is sandwiched by two glass plates, moisture that has passed through the acrylic resin plate under moist heat conditions Since it is easy to condense in a laminated body, it is easy to generate|occur|produce whitening in an adhesive layer. However, according to the adhesive which concerns on this embodiment, also in an above-described laminated body, the outstanding wet-and-heat whitening resistance is exhibited.

[adhesive sheet]

The pressure-sensitive adhesive sheet according to the present embodiment is at least 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 or both surfaces of the pressure-sensitive adhesive layer.

A specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in FIG. 1 .

As shown in FIG. 1 , the pressure-sensitive adhesive sheet 1 according to the embodiment includes two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. It is comprised by the adhesive layer 11 clamped by each release sheet 12a, 12b. In addition, the peeling surface of the peeling sheet in this specification means the surface which has peelability in a peeling sheet, and includes both the surface which gave peeling process, and the surface which shows peelability even if it does not perform a peeling process.

1. Each member

(1) adhesive layer

The adhesive layer 11 is comprised from the adhesive mentioned above, ie, it is comprised from the active-energy-ray-curable adhesive formed by bridge|crosslinking (thermal-crosslinking) the adhesive composition P.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 has a crosslinked structure composed of a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B), and contains an active energy ray-curable component (C) (before curing). and, if desired, a photoinitiator (D) and an additive are further contained.

As a lower limit, it is preferable that it is 10 micrometers or more, and, as for the thickness (value measured based on JISK7130) of the adhesive layer 11 in the adhesive sheet 1 which concerns on this embodiment, it is more preferable that it is 25 micrometers or more, 50 It is especially preferable that it is more than micrometer. If the lower limit of the thickness of the adhesive layer 11 is the above, it is easy to exhibit desired adhesive force, and sufficient level difference followable|trackability can be ensured with respect to the normal level difference of a display body structural member.

Moreover, as for the thickness of the adhesive layer 11, it is preferable as an upper limit that it is 1000 micrometers or less, It is more preferable that it is 600 micrometers or less, It is especially preferable that it is 300 micrometers or less, It is still more preferable that it is 150 micrometers or less. When the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is the above, moisture-and-heat whitening resistance becomes more excellent, and it is easy to exhibit the outstanding blister resistance. Moreover, the adhesive layer 11 may be formed in a single layer, and may be formed by laminating|stacking multiple layers.

(2) release sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (the 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.

As the release sheets 12a and 12b, for example, 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, a polyethylene Naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, poly A carbonate film, a polyimide film, a fluororesin film, etc. are used. Moreover, these crosslinked films are also used. Moreover, these laminated|multilayer films may be sufficient.

It is preferable that the peeling process is given to the peeling surface (particularly, the surface in contact with the adhesive layer 11) of the said peeling sheet 12a, 12b. As a release agent used for a peeling process, the release agent of an alkyd type, a silicone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type is mentioned, for example. Moreover, among the release sheets 12a, 12b, it is preferable to use one release sheet as a medium release type release sheet with a large peeling force, and to use the other release sheet as a light release type release sheet with a small peel force.

Although there is no restriction|limiting in particular about the thickness of peeling sheet 12a, 12b, Usually, it is about 20-150 micrometers.

2. Physical properties

(1) Haze value

It is preferable that the haze value of the adhesive layer 11 of the adhesive sheet 1 which concerns on this embodiment is 5 % or less, It is more preferable that it is 3 % or less, It is especially preferable that it is 1 % or less, It is still more preferable that it is 0.5 % or less. do. Transparency is very high that the haze value of the adhesive layer 11 is 5 % or less, and it is suitable as an optical use (for display body). Moreover, the haze value of an adhesive layer does not change also after hardening by active energy ray irradiation. The haze value in this specification is made into the value measured based on JISK7136:2000.

(2) Transmissive color b*

It is preferable that the transmission color b* defined by the CIE1976 L*a*b* color system of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is -2.0 to 2.0, and it is -1.5 to 1.5 It is especially preferable, and it is more preferable that it is -1.0-1.0. When the transmissive color b* of the pressure-sensitive adhesive layer 11 is within the above range, the pressure-sensitive adhesive layer 11 has little coloration and is particularly suitable for displays. In the present embodiment, the (meth)acrylic acid ester polymer (A) contains an appropriate amount of N-vinylcarboxylic acid amide as a monomer unit constituting the polymer, whereby it is possible to achieve the above-described transmission hue b*. Moreover, the transmission hue b* of an adhesive layer does not change also after hardening by active energy ray irradiation. The measuring method of the transmitted hue b* in this specification is as showing in the test example mentioned later.

(3) Adhesion (after active energy ray irradiation)

When the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is cured by irradiation with an active energy ray to obtain a pressure-sensitive adhesive layer after curing, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet to soda lime glass is as a lower limit It is preferable that it is 5 N/25 mm or more, It is especially preferable that it is 10 N/25 mm or more, It is more preferable that it is 15 N/25 mm or more. If the adhesive force of the adhesive sheet 1 is 5 N/25 mm or more, it will become more excellent in blister resistance and step|step difference followable|trackability under high temperature, high humidity conditions. On the other hand, although the upper limit of the said adhesive force is not specifically limited, Usually, it is preferable that it is 50 N/25 mm or less, It is more preferable that it is 45 N/25 mm or less, It is especially preferable that it is 40 N/25 mm or less.

Although the said adhesive force basically refers to the adhesive force measured by the 180 degree peeling method based on JIS Z0237:2009, the measurement sample shall be 25 mm width and 100 mm length, The said measurement sample is affixed to a to-be-adhered body, and 0.5 After pressurizing at MPa and 50°C for 20 minutes, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays to obtain a pressure-sensitive adhesive layer after curing. It shall be measured at a speed of 300 mm/min.

3. Preparation of adhesive sheet

As one manufacturing example of the adhesive sheet 1, the application solution of the said adhesive composition P is apply|coated to the peeling surface of one peeling sheet 12a (or 12b), it heat-processes, heat-crosslinks the adhesive composition P, and apply|coating After forming the layer, the release surface of the other release sheet 12b (or 12a) is superposed on the application layer. By providing a curing period when a curing period is required, the said application layer becomes the adhesive layer 11 as it is when a curing period is unnecessary. Thereby, the said adhesive sheet 1 is obtained. About the conditions of heat processing and curing, it is as above-mentioned.

As another manufacturing example of the adhesive sheet 1, the coating solution of the said adhesive composition P is apply|coated to the peeling surface of one peeling sheet 12a, heat-processing is performed, the adhesive composition P is thermally crosslinked, and an application layer is formed, , the release sheet 12a with an application layer is obtained. Furthermore, the coating solution of the said adhesive composition P is apply|coated to the peeling surface of the other peeling sheet 12b, heat-processing is performed, the adhesive composition P is thermally crosslinked, the coating layer is formed, The peeling sheet with an application layer (12b) is obtained. And the release sheet 12a with an application layer and the release sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When a curing period is required, by providing a curing period, when a curing period is unnecessary, the above-described laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this manufacturing example, even if it is a case where the adhesive layer 11 is thick, it becomes possible to manufacture stably.

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, etc. can be used.

[display body]

As shown in FIG. 2, as for the display body 2 which concerns on this embodiment, the 1st display body structural member 21 (one display body structural member) which has a level|step difference in the surface on the side bonded at least, and the 2nd The display body structural member 22 (another display body structural member) and the post-hardening adhesive layer 11 which are located between them and bond the 1st display body structural member 21 and the 2nd display body structural member 22 together mutually. ') is provided. In the display body 2 which concerns on this embodiment, the 1st display body structural member 21 has a level|step difference in the surface by the side of the adhesive layer 11' after hardening, Specifically, to the printing layer 3 has a step difference by

The adhesive layer 11' after hardening in the said display body 2 hardens the adhesive layer 11 of the adhesive sheet 1 mentioned above by energy-beam irradiation. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11' after this curing has a crosslinked structure composed of a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B), and is a cured product of an energy ray-curable component (C) ( polymer), and if desired, a photoinitiator (D) and an additive are further contained. It is estimated that the superposed|polymerized energy-beam sclerosing|hardenable component (C) is entangled in the crosslinked structure comprised by the (meth)acrylic acid ester polymer (A) and the thermal crosslinking agent (B), and forms a higher order structure.

In addition, the photopolymerization initiator (D) contained in the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11' after curing, the photopolymerization initiator (D) contained in the pressure-sensitive adhesive composition P, remains without cleavage even by energy ray irradiation. . Therefore, the content is not much and is usually 0.00001 mass % or more and 0.1 mass % or less in an adhesive, Preferably, they are 0.0001 mass % or more and 0.01 mass % or less.

It is preferable that the adhesive layer 11' after curing (adhesive of) has the following physical properties.

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

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

The gel fraction of the pressure-sensitive adhesive (after active energy ray irradiation) of the pressure-sensitive adhesive layer 11' after curing is preferably 95% or less, particularly preferably 93% or less, and more preferably 90% or less. If the upper limit of the gel fraction of the pressure-sensitive adhesive of the pressure-sensitive adhesive layer 11' after curing is the above, it is possible to prevent deterioration of durability due to a decrease in the adhesive force of the pressure-sensitive adhesive layer 11' after curing. The measurement method of the gel fraction of the adhesive (after active energy ray irradiation) of the adhesive layer 11' after this hardening is as showing in the test example mentioned later.

(2) Step tracking rate

After curing, the pressure-sensitive adhesive layer 11' has a step difference (%) expressed by the following formula, as a lower limit, preferably 15% or more, more preferably 20% or more, particularly preferably 25% or more, 35 % or more is more preferable. In addition, although it does not specifically limit as an upper limit of step|step difference tracking rate, Usually, it is preferable that it is 80 % or less, and it is especially preferable that it is 70 % or less.

Level difference follow-up rate (%) = {(After a predetermined durability test, the height of the level difference maintained without bubbles, lifting, peeling, etc. (㎛))/(thickness of the adhesive layer)}×100

In addition, the test method of the level|step difference tracking rate is as showing in the test example mentioned later.

Since the step difference tracking rate of the pressure-sensitive adhesive layer 11' after curing is in the above range, the post-curing pressure-sensitive adhesive layer 11' is a display body structural member (first display body structural member 21) even after passing through a durability test. )), the occurrence of bubbles, floating, peeling, and the like in the vicinity of the step is suppressed, thereby suppressing the occurrence of reflection loss of light.

(3) permittivity

The dielectric constant at 1.0 MHz of the adhesive (after active energy ray irradiation) of the adhesive layer 11' after curing is preferably 6.0 or less, particularly preferably 5.8 or less, and more preferably 5.5 or less. Since the upper limit of the dielectric constant is the above, it can contribute to suppression of malfunction of the touch panel and improvement of responsiveness. If it is the adhesive layer 11' after curing formed using the (meth)acrylic acid ester polymer (A) having a component derived from N-vinylcarboxylic acid amide and the active energy ray-curable component (C), a low dielectric constant as described above is achieved. can do.

Although the lower limit of the dielectric constant at 1.0 MHz of the adhesive (after active energy ray irradiation) of the adhesive layer 11' after curing is not particularly limited, usually, it is preferably 3.5 or more, and particularly preferably 3.8 or more, It is more preferable that it is 4.0 or more. Moreover, since the dielectric constant of an adhesive changes before and after irradiation with an active energy ray, the dielectric constant after irradiation with an active energy ray becomes important. The measuring method of the dielectric constant of an adhesive is as showing in the test example mentioned later.

As the display body 2, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescent (organic EL) display, electronic paper etc. are mentioned, for example, A touch panel may be sufficient. In addition, as the display body 2, the member which comprises them may be sufficient.

It is preferable that it is a protective panel which consists of a laminated body etc. which contain them other than a glass plate, a plastic plate, etc., and, as for the 1st display body structural member 21, it is especially preferable that it is a plastic plate. In this case, it is common that the printing layer 3 is formed in the adhesive layer 11 side in the 1st display body structural member 21 in the shape of a frame frame.

It does not specifically limit as said glass plate, For example, chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium strontium containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. are used. can be heard Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

It does not specifically limit as said plastic board, For example, an acrylic resin board, a polycarbonate board, etc. are mentioned. Although the thickness of a plastic plate is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

Moreover, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard-coat layer, a glare-proof layer, etc.) may be provided on the single side|surface or both surfaces of the said glass plate or a plastic plate, and the optical member may be laminated|stacked. In addition, the transparent conductive film and the metal layer may be patterned.

The 2nd display body structural member 22 is the optical member which should be affixed to the 1st display body structural member 21, a display body module (For example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electro It is preferable that it is a laminated body containing a luminescence (organic EL) module etc., the optical member as a part of a display body module, or a display body module.

Examples of the optical member include an anti-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improving film, a contrast enhancing film, a liquid crystal polymer film, a diffusing film, a transflective film A film, a transparent conductive film, etc. are mentioned. As an anti-scattering film, the hard-coat film etc. in which the hard-coat layer is formed in the single side|surface of a base film are illustrated.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing is used. The thickness of the printed layer 3, that is, the lower limit of the height of the step, is preferably 3 µm or more, more preferably 5 µm or more, particularly preferably 7 µm or more, and most preferably 10 µm or more. When the lower limit is the above, it is possible to sufficiently secure the hiding properties such as making the electric wiring invisible from the viewer side. Moreover, it is preferable that it is 50 micrometers or less, and, as for an upper limit, it is more preferable that it is 35 micrometers or less, It is especially preferable that it is 25 micrometers or less, It is still more preferable that it is 20 micrometers or less. When the upper limit is the above, it is possible to prevent deterioration of the level difference followability of the pressure-sensitive adhesive layer 11 with respect to the printed layer 3 .

In order to manufacture the said display body 2, as an example, one peeling sheet 12a of the adhesive sheet 1 is peeled, and the adhesive layer 11 which exposed the adhesive sheet 1 is a 1st display body. It is bonded to the surface of the structural member 21 on the side where the printed layer 3 exists. At this time, since the pressure-sensitive adhesive layer 11 is excellent in the initial step difference followability, it is suppressed that a gap or float occurs in the vicinity of the step difference due to the printed layer 3 .

Next, the other release sheet 12b is peeled off 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 body structural member 22 of the pressure-sensitive adhesive sheet 1 are exposed. are bonded together to obtain a laminate. Moreover, you may change the bonding order of the 1st display body structural member 21 and the 2nd display body structural member 22 as another example.

Then, an active energy ray is irradiated with respect to the adhesive layer 11 in the said laminated body. Thereby, the energy-beam curable component (C) in the adhesive layer 11 superposes|polymerizes, the adhesive layer 11 hardens|cures, and it becomes the adhesive layer 11' after hardening. Irradiation of the energy-beam to the adhesive layer 11 is normally performed over either the 1st display body structural member 21 or the 2nd display body structural member 22, Preferably, 1st display as a protection panel It is performed over the sieve structural member 21.

Here, an active energy ray means what has an energy proton in an electromagnetic wave or a charged particle beam, Specifically, an ultraviolet-ray, an electron beam, etc. are mentioned. Among active energy rays, an easy-to-handle ultraviolet-ray is particularly preferable.

Irradiation of ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and it is preferable that the irradiation amount of ultraviolet-ray is about 50-1000 mW/cm<2> of illumination intensity. Moreover, it is preferable that the amount of light is 50-10000 mJ/cm<2>, It is more preferable that it is 80-5000 mJ/cm<2>, It is especially preferable that it is 200-2000 mJ/cm<2>. On the other hand, irradiation of an electron beam can be performed with an electron beam accelerator etc., The irradiation amount of an electron beam is preferably about 10-1000 krad.

In the display body 2 described above, since the pressure-sensitive adhesive layer 11' after curing is excellent in step difference followability even under high temperature and high humidity conditions, the display body 2 is subjected to high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours), it is suppressed from generation|occurrence|production of a bubble, a float, peeling, etc. in the step|step difference vicinity.

In addition, in the display body 2, since the pressure-sensitive adhesive layer 11' after curing is excellent in blister resistance, the display body 2 is subjected to high temperature and high humidity conditions (for example, 85 ° C., 85% RH, 72 hours), even when outgas is generated from the first display body structural member 21 and/or the second display body structural member 22, the adhesive layer 11' and the display body structural member ( 21, 22), the generation of blisters such as air bubbles, floating, peeling, and the like is suppressed.

Moreover, in the said display body 2, since the adhesive layer 11' after the said hardening is excellent in heat-and-moisture whitening resistance, the display body 2 under high-temperature, high-humidity conditions (for example, 85 degreeC, 85%) RH, 120 hours) and then, even when returned to normal temperature and humidity, whitening of the pressure-sensitive adhesive layer 11' after curing is suppressed. According to the display body 2 which concerns on this embodiment especially, even if one of the 1st display body structural member 21 and the 2nd display body structural member 22 is a plastic plate 1 mm or more in thickness, even if the other is a glass plate , excellent heat-and-moisture whitening resistance is exhibited.

In addition, since the dielectric constant of the pressure-sensitive adhesive layer 11' after curing is suppressed low, even when the display body 2 is a touch panel, malfunction of the touch panel due to the dielectric constant of the pressure-sensitive adhesive layer 11' after curing is It is suppressed effectively, and the responsiveness of the said touchscreen is favorable.

The embodiment described above is described in order to facilitate the understanding of the present invention, and is not described in order to limit the present invention. Accordingly, each element disclosed in the above embodiment is intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, either one of the peeling sheets 12a and 12b in the adhesive sheet 1 may be abbreviate|omitted. In addition, the 1st display body structural member 21 may have a level difference other than the printing layer 3, and does not need to have a level difference. In addition, not only the 1st display body structural member 21 but the 2nd display body structural member 22 may have a level difference in the adhesive layer 11' side after hardening.

(Example)

Hereinafter, the present invention will be described in more detail by way of 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 in a solution polymerization method was copolymerized to prepare a (meth)acrylic acid ester polymer (A). When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method mentioned later, it was a weight average molecular weight (Mw) 500,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the step 1 (solid content conversion; the same applies below), and trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (B) (manufactured by Toyo Chem Corporation, product name “BHS8515”) 0.15 parts by mass, 5 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate as an active energy ray-curable component (C), and benzophenone and 1-hydroxy as a photoinitiator (D) 0.5 parts by mass of a mixture obtained by mixing cyclohexylphenyl ketone in a mass ratio of 1:1, and 0.30 mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") The parts were mixed, stirred sufficiently, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

Here, each compounding (solid content conversion value) of the adhesive composition at the time of making the (meth)acrylic acid ester polymer (A) 100 mass parts (solid content conversion value) is shown in Table 1. In addition, details, such as abbreviation of Table 1, are as follows.

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

2EHA: Acrylic acid 2-ethylhexyl

ACMO: 4-acryloylmorpholine

IBXA: isobornyl acrylate

NVA: N-vinylacetamide

HEA: Acrylic acid 2-hydroxyethyl

MMA: methyl methacrylate

BA: n-butyl acrylate

[Crosslinking agent (B)]

TDI: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Chem, product name "BHS8515")

Epoxy type: 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemicals, product name "TETRAD-C")

3. Preparation of adhesive sheet

The application solution of the pressure-sensitive adhesive composition obtained in step 2 is applied to the release-treated surface of a medium-peelable release sheet (manufactured by Lintex, product name “SP-PET752150”) in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent, and applied with a knife coater did. And with respect to the application layer, it heat-processed at 90 degreeC for 1 minute, and the application layer was formed.

Next, the light-peelable release sheet (manufactured by Lintexa, product name "SP-PET382120"), in which the coating layer on the medium-peelable release sheet obtained above, and one side of the polyethylene terephthalate film were subjected to peeling treatment with a silicone-based release agent, was applied to the light-peelable release sheet. was bonded so that the release-treated surface of the coating layer was in contact with the application layer, and was cured for 7 days under the conditions of 23 ° C. and 50% RH, so that a medium release type release sheet/adhesive layer (thickness: 25 µm)/light release type release sheet was formed. The 1st adhesive sheet was produced.

In addition, the coating solution of the adhesive composition obtained in step 2 was applied to the peeling-treated side of a medium release type release sheet (manufactured by Lintex, product name "SP-PET752150") in which one side of the polyethylene terephthalate film was peeled off with a silicone release agent, with a knife coater After coating with , heat treatment was performed at 90° C. for 1 minute to form a coating layer (thickness: 25 μm). Similarly, the application solution of the pressure-sensitive adhesive composition obtained in step 2 was applied to the peeling treatment side of a light-peelable release sheet (manufactured by Lintex, product name “SP-PET382120”) in which one side of the polyethylene terephthalate film was peeled off with a silicone-based release agent. After coating with , heat treatment was performed at 90° C. for 1 minute to form a coating layer (thickness: 25 μm).

Next, the medium release type release sheet with an application layer obtained above and the light release type release sheet with an application layer obtained above are bonded together so that both application layers are in contact with each other, and the conditions of 23°C and 50% RH for 7 days By curing, the 2nd adhesive sheet which consists of a structure of a medium-peelable release sheet/adhesive layer (thickness: 50 micrometers)/light-peelable release sheet was produced.

In addition, based on JISK7130, the thickness of the said adhesive layer is the value measured using the static pressure thickness meter (the Techroxa make, product name "PG-02").

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

The type and ratio 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 type and blending amount of the crosslinking agent (B), the active energy ray-curable component Except changing the compounding quantity of (C) and the compounding quantity of a photoinitiator (D) as Table 1 shows, it carried out similarly to Example 1, and manufactured the 1st and 2nd adhesive sheet.

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

<Measurement conditions>

・GPC measuring device: Dosoh Corporation, HLC-8020

·GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

・Measurement solvent: tetrahydrofuran

・Measurement temperature: 40℃

[Test Example 1] (Measurement of gel fraction)

The first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm) obtained in Examples and Comparative Examples was cut to a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200), and the mass was measured with a precision balance, and the mass of only the adhesive was computed by subtracting the mass of the said mesh independent. Let the mass at this time be M1.

Next, the adhesive wrapped with the said polyester mesh was immersed in ethyl acetate at room temperature (23 degreeC) for 24 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in 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 measured with a precision balance, and the mass of only the adhesive was computed by subtracting the mass of the said mesh independent. Let the mass at this time be M2. The gel fraction (%) is expressed as (M2/M1) x 100. Thereby, the gel fraction (before UV irradiation) of the adhesive was derived. A result is shown in Table 2.

On the other hand, with respect to the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm) obtained in Examples and Comparative Examples, the pressure-sensitive adhesive layer is cured by irradiating ultraviolet rays (UV) over the light-peelable release sheet under the following conditions. It was made into an adhesive layer after hardening. About the adhesive of the adhesive layer after this hardening, it carried out similarly to the above, and the gel fraction (after UV irradiation) was derived|led-out. A result is shown in Table 2.

<Ultraviolet irradiation conditions>

・Use of high pressure mercury lamp

Illuminance 200mW/cm2, light intensity 2000mJ/cm2

・UV illuminance and light meter use “UVPF-A1” manufactured by Eye Graphics.

[Test Example 2] (Measurement of haze value)

About the adhesive layer of the 1st adhesive sheet (the thickness of an adhesive layer: 25 micrometers) obtained in the Example and the comparative example, based on JISK7136:2000, according to the haze meter (made by Nippon Denshoku Kogyo Co., Ltd., product name "NDH-2000") was used to measure the haze value (%). A result is shown in Table 2.

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

With respect to the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm) obtained in Examples and Comparative Examples, CIE1976 L* using a simultaneous photometric spectroscopic colorimeter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name “SQ2000”) The transmitted color b* defined by the a*b* color system was measured. A result is shown in Table 2.

[Test Example 4] (Measurement of adhesive force)

The light-peelable release sheet was peeled from the 1st adhesive sheet (thickness of an adhesive layer: 25 micrometers) obtained in the Example and a comparative example, and the exposed adhesive layer is polyethylene terephthalate (PET) which has an easily adhesive layer. It was bonded to the easily adhesive layer of a film (The Toyobo Corporation make, product name "PET A4300", thickness: 100 micrometers), and the laminated body of the peeling sheet / adhesive layer / PET film was obtained. The obtained laminate was cut into 25 mm width and 100 mm length.

In an environment of 23°C and 50% RH, the medium release type release sheet was peeled from the laminate, and the exposed pressure-sensitive adhesive layer was affixed to soda lime glass (manufactured by Nippon Ita Glass), and 0.5 with an autoclave made by Kurihara Sesakusho Co., Ltd. It pressurized at MPa and 50 degreeC for 20 minutes. Then, ultraviolet-ray (UV) was irradiated with respect to the adhesive layer over the PET film under the same ultraviolet irradiation conditions as in Test Example 1, the adhesive layer was hardened, and it was set as the adhesive layer after hardening. After standing for 24 hours under the conditions of 23° C. and 50% RH, the sample having the pressure-sensitive adhesive layer after curing was subjected to a tensile tester (manufactured by Orientex, Tensilon), a peeling rate of 300 mm/min, a peeling angle of 180 The adhesive force (after UV irradiation; N/25 mm) was measured under the conditions shown in the figure. Conditions other than those described herein were measured in accordance with JIS Z 0237:2009. A result is shown in Table 2.

[Test Example 5] (Evaluation of blister resistance)

A polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd.) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side of the pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 µm) obtained in Examples and Comparative Examples. An ITO film, thickness: 125 µm) was sandwiched between a transparent conductive film and an acrylic resin plate (manufactured by Mitsubishi Rayon, product name "Acrylite MR-200", thickness: 1 mm). Then, it autoclaved under the conditions of 50 degreeC and 0.5 MPa for 30 minutes, and left it to stand at normal pressure, 23 degreeC, 50%RH for 24 hours.

About the adhesive layer of the obtained laminated body, ultraviolet-ray was irradiated over the said resin plate on the conditions similar to Test Example 1, the adhesive layer was hardened, and it was set as the adhesive layer after hardening. Next, it was stored for 72 hours under high-temperature, high-humidity conditions of 85°C and 85% RH. Then, the state in the interface of the adhesive layer and to-be-adhered body after hardening was confirmed visually, and the following references|standards evaluated blister resistance. A result is shown in Table 2.

○: There were no bubbles, lifting, or peeling off.

×: Bubbles or floating/peeling occurred

[Test Example 6] (Measurement of step difference tracking rate)

On the surface of a glass plate (manufactured by NSG Precision, product name "Corning Glass Eagle XG," length 90 mm x width 50 mm x thickness 0.5 mm), UV-curable ink (manufactured by Deco Ink, product name "POS-911 ink") is applied and the thickness is It was screen-printed on the frame border shape (external shape: 90 mm long x 50 mm wide, 5 mm width) so that it might become any of 10 micrometers, 15 micrometers, and 20 micrometers. Next, UV light is irradiated (80 W/cm 2 , metal halide lamp 2 lights, lamp height 15 cm, belt speed 10-15 m/min) to cure the printed UV curable ink, : 10 µm, 15 µm, or 20 µm) was prepared.

The light-peelable release sheet was peeled off from the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 μm) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was placed on a polyethylene terephthalate (PET) film having an easily adhesive layer (manufactured by Toyobo Corporation, The product name "PET A4300", thickness: 100 micrometers) was bonded to the easily adhesive layer. Next, the heavy release type release sheet was peeled off to expose the pressure-sensitive adhesive layer, and using a laminator (manufactured by Fuji Plastics, product name "LPD3214"), the pressure-sensitive adhesive layer was laminated on each step-attached glass plate so as to cover the entire printed surface on the frame border. Then, it autoclaved under the conditions of 50 degreeC and 0.5 MPa for 30 minutes, and left it to stand at normal pressure, 23 degreeC, 50%RH for 24 hours.

About the adhesive layer of the obtained laminated body, ultraviolet-ray was irradiated on the conditions similar to Test Example 1 over the said PET film, the adhesive layer was hardened, and it was set as the adhesive layer after hardening. Next, it was stored for 72 hours under high-temperature, high-humidity conditions of 85°C and 85% RH (durability test), and thereafter, step followability was evaluated. Step followability is judged by whether or not the printing step is completely filled by the pressure-sensitive adhesive layer after curing. judged to be unable to do so. Here, the level difference followability was evaluated as the level difference followability ratio (%) expressed by the following formula. A result is shown in Table 2.

Level difference follow-up rate (%) = {(After the durability test, the height of the level difference maintained without air bubbles, lifting, peeling, etc. (㎛)) / (thickness of the adhesive layer after curing)} × 100

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

The pressure-sensitive adhesive layer of the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 µm) obtained in Examples and Comparative Examples was applied to an alkali-free glass plate having a thickness of 1.1 mm and an acrylic resin plate having a thickness of 1 mm (manufactured by Mitsubishi Rayon, product name “Acry”). light MR-200") to obtain a laminate.

After autoclaving the obtained laminated body under the conditions of 50 degreeC and 0.5 MPa for 30 minutes, it was left to stand at normal pressure, 23 degreeC, 50%RH for 24 hours. Then, about the adhesive layer of the said laminated body, ultraviolet-ray was irradiated on the conditions similar to Test Example 1 over the said acrylic resin board, the adhesive layer was hardened, and it was set as the adhesive layer after hardening. About this laminated body (sample), the haze value (%) was measured based on JISK7136:2000 using the haze meter (The Nippon Denshoku Kogyo Co., Ltd. make, product name "NDH2000").

Next, the laminate was stored for 120 hours under moist heat conditions of 85°C and 85% RH, and then left to stand for 24 hours at 23°C and 50% RH at room temperature and humidity. About the said laminated body, haze value (%) was measured based on JISK7136:2000 using the haze meter (The Nippon Denshoku Kogyo Co., Ltd. make, product name "NDH2000").

Based on the above result, the haze value before wet heat condition was subtracted from the haze value after wet heat condition, and haze value rise (point) after wet heat condition was computed. Based on the result, the following reference|standard evaluated moisture-and-heat whitening resistance. A result is shown in Table 2.

◎: haze value increase is less than 1.0 point

○: Haze value rise is 1.0 point or more, less than 5.0 point

×: The haze value increase is 5.0 points or more

[Test Example 8] (Calculation of dielectric constant)

After forming a 100-micrometer-thick adhesive layer on the single side|surface of a 50-micrometer-thick polyethylene terephthalate film similarly to an Example and a comparative example, and bonding a 50-micrometer-thick polyethylene terephthalate film to the adhesive layer, 50 mm It cut to x50 mm. Then, ultraviolet-ray (UV) was irradiated on the following conditions, the adhesive layer was hardened, and it was set as the adhesive layer after hardening.

<Ultraviolet irradiation conditions>

・Use of high pressure mercury lamp

Illuminance 200mW/cm2, light intensity 1000mJ/cm2

・UV illuminance and light meter use “UVPF-A1” manufactured by Eye Graphics.

About the obtained laminated body, the electrostatic capacitance (C1) was measured using the impedance analyzer (Nippon Hewlett-Packard company make, "HP-4194A"). Moreover, the said 50-micrometer-thick polyethylene terephthalate film overlapped 2 sheets, and it cut out to 50 mm x 50 mm, and similarly carried out the electrostatic capacitance (C2) was measured. And, from the values of C1 and C2, the calculation formula of the series-connected capacitor

1/C1=1/C2+1/C3

Based on this, the electrostatic capacity (C3) of the pressure-sensitive adhesive was calculated. Based on this electrostatic capacitance C3, the dielectric constant (epsilon) _s of an adhesive was computed from the following formula. A result is 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: the electrostatic capacity of the adhesive

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

d: the 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 Examples was excellent in blister resistance, step tracking property, and wet heat and whitening resistance, and also exhibited a low dielectric constant. .

The pressure-sensitive adhesive composition, pressure-sensitive adhesive, and pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding, for example, a protective panel made of a plastic plate and a desired display body structural member. Moreover, the display body which concerns on this invention is suitable as a capacitive-type touch panel, for example.

1: adhesive sheet
11: adhesive layer
12a, 12b: release sheet
2: display body
11': adhesive layer after curing
21: 1st display body structural member
22: 2nd display body structural member
3: print layer

Claims (9)

An adhesive sheet provided with an adhesive layer, comprising:
The pressure-sensitive adhesive layer,
As a monomer unit constituting the polymer, a (meth)acrylic acid ester polymer (A) containing N-vinylcarboxylic acid amide and a reactive functional group-containing monomer having a reactive functional group in the molecule, and a crosslinking agent (B) that reacts with the reactive functional group While having a cross-linked structure that becomes
containing an active energy ray-curable component (C)
consisting of an active energy ray-curable adhesive
Adhesive sheet, characterized in that. delete According to claim 1,
In the (meth)acrylic acid ester polymer (A), the mass ratio of the reactive functional group-containing monomer as a monomer unit constituting the polymer to the N-vinylcarboxylic acid amide is 95:5 to 50:50, characterized in that adhesive sheet. According to claim 1,
The said (meth)acrylic acid ester polymer (A) contains 5 mass % or more and 30 mass % or less of the said reactive functional group containing monomer as a monomer unit which comprises the said polymer, The adhesive sheet characterized by the above-mentioned. delete According to claim 1,
The adhesive sheet, characterized in that the gel fraction of the pressure-sensitive adhesive is 30% or more and 90% or less. According to claim 1,
In a laminate in which an adhesive layer having a thickness of 50 μm made of the pressure-sensitive adhesive is sandwiched between a glass plate and an acrylic resin plate having a thickness of 1 mm, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays to obtain a pressure-sensitive adhesive layer after curing, and then the laminate With respect to, from the haze value before the endurance test, from the haze value at the time of storing for 120 hours under a moist heat condition of 85 ° C. and 85% RH, and then stored for 24 hours at 23 ° C., 50% RH at room temperature and humidity. The increase in haze value minus the value is less than 5 points, The adhesive sheet characterized by the above-mentioned. According to claim 1,
provided with two release sheets,
The pressure-sensitive adhesive layer was sandwiched by the release sheet so as to be in contact with the release surfaces of the two release sheets.
Adhesive sheet, characterized in that. One display body component,
and other display body constituent members;
The after-hardening adhesive layer which bonds said one display body structural member and the said other display body structural member together mutually
As a display body provided with
At least one of the said one display body structural member and the said other display body structural member consists of a plastic plate,
After the curing, the pressure-sensitive adhesive layer is a (meth)acrylic acid ester polymer (A) comprising N-vinylcarboxylic acid amide as a monomer unit constituting the polymer and a reactive functional group-containing monomer having a reactive functional group in the molecule, and the reactive functional group. It has a crosslinked structure comprised from a crosslinking agent (B), and consists of an adhesive containing the hardened|cured material of an active energy ray-curable component (C).
A display body, characterized in that.

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