JP2019210445A - Photocurable pressure-sensitive adhesive sheet - Google Patents

Abstract

To provide a new pressure-sensitive adhesive sheet relating to a pressure-sensitive adhesive sheet to be used for laminating a resin member, which has a photocuring property and achieves both step absorbability and anti-foaming reliability.SOLUTION: A photocurable pressure-sensitive adhesive sheet is provided for laminating a resin member (X) having a light transmittance of 10% or less at a wavelength of 365 nm and a light transmittance of 60% or more at a wavelength of 405 nm, and has a pressure-sensitive adhesive layer (Y) having all of the following characteristics (1) to (3). The pressure-sensitive adhesive layer has (1) a gel fraction within the range from 0 to 60% and (2) a light transmittance of 89% or less at a wavelength of 390 nm and a light transmittance of 80% or more at a wavelength of 410 nm, and has (3) such a photocuring property that the layer is cured by irradiation with light at a wavelength of 405 nm.SELECTED DRAWING: None

Description

  The present invention is a pressure-sensitive adhesive sheet used for laminating a resin member having an ultraviolet ray-cutting property that does not transmit ultraviolet rays, and has a capability of being cured by irradiating light (referred to as “photocurability”). The present invention relates to a photocurable pressure-sensitive adhesive sheet.

  In recent years, in order to improve the visibility of an image display device, an image display panel such as a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD), and a protection disposed on the front side (viewing side). By filling the gap between the panel and the touch panel member with an adhesive, reflection of incident light and outgoing light from the display image at the air layer interface is suppressed.

  As a method for filling the gap between the constituent members for an image display device with an adhesive, there is a method in which a liquid adhesive resin composition containing an ultraviolet curable resin is filled into the gap and then cured by irradiation with ultraviolet rays. Known (Patent Document 1).

  In addition, a method of filling a gap between constituent members for an image display device using an adhesive sheet is also known. For example, Patent Document 2 discloses a method in which a pressure-sensitive adhesive sheet that has undergone primary crosslinking with ultraviolet rays is bonded to an image display device constituent member, and then the adhesive sheet is irradiated with ultraviolet rays through the image display device constituent member to be secondarily cured. .

  In Patent Document 3, when an image display device constituent member having a stepped portion on a bonding surface is bonded via a transparent double-sided adhesive sheet, it can be filled up to every corner following the stepped portion. Moreover, as a new transparent double-sided adhesive sheet that can alleviate the distortion generated in the adhesive sheet and maintain the foaming resistance under high temperature and high humidity without impairing the handling property, ) Acrylic ester (co) polymer, an ultraviolet polymerization initiator (A) having a molar extinction coefficient at a wavelength of 365 nm of 10 or more and a molar extinction coefficient at a wavelength of 405 nm of 0.1 or less, and a molar absorbance at a wavelength of 405 nm And a visible light polymerization initiator (B) having a coefficient of 10 or more, and the dynamic storage elastic modulus (E ′) at 60 ° C. determined by the tensile method is the dynamic storage elastic modulus at 60 ° C. determined by the shear method ( G ') divided by (E' A transparent double-sided adhesive sheet in the B-stage state with / G ′) of 10 or more has been proposed.

International Publication No. 2010/027041 Japanese Patent No. 4971529 JP 2014-152295 A

When two image display device constituent members are attached using the photocurable adhesive sheet as described above, one image display is performed after the two image display device constituent members are primarily attached via the adhesive sheet. The adhesive sheet can be secondarily attached by irradiating ultraviolet rays from the outside of the apparatus constituent member and curing the adhesive sheet through the image display apparatus constituent member with ultraviolet rays.
According to such a method, primary adhesion can be performed while filling the unevenness of the adherend surface, and adhesion reliability can be further enhanced by finally curing with ultraviolet rays. It is possible to achieve both “step difference absorbability” in the case where there are irregularities on the adherend surface of the “bonding member” and “foaming resistance reliability” after bonding.

For example, in an in-vehicle image display device or the like, a resin front panel is used to prevent scattering of glass, and a resin member such as a conductive member or a polarizing plate may be disposed inside the resin front panel. In this case, since it is necessary to prevent deterioration such as yellowing of the front panel and the resin member such as a conductive member and a polarizing plate arranged on the inner side due to exposure to ultraviolet rays, the resin members on the side exposed to the ultraviolet rays are not included. An ultraviolet absorber is blended to give the ability to absorb ultraviolet rays.
However, in this case, as described above, it is not possible to irradiate ultraviolet rays from the outside of the image display device constituent member and to cure the adhesive sheet through the image display device constituent member.
For this reason, when the resin front panel is bonded, a non-photocurable pressure-sensitive adhesive sheet that is sufficiently cured to have foaming reliability and has no photocurability must be used.
However, such a non-photocurable pressure-sensitive adhesive sheet is not always satisfactory in terms of step absorbability.

  The present invention can be bonded to a resin member having an ultraviolet cutting property that does not transmit ultraviolet rays, and has a step absorbability when the bonding surface of the bonding member has irregularities and a foam resistance reliability after bonding. A new pressure-sensitive adhesive sheet that can be made compatible is provided.

The present invention relates to a resin member having an ultraviolet cutting property that does not transmit ultraviolet light, that is, a resin member (X) having a light transmittance of 10% or less at a wavelength of 365 nm and a light transmittance of 60% or more at a wavelength of 405 nm. It is a photocurable pressure-sensitive adhesive sheet used for pasting,
A photocurable pressure-sensitive adhesive sheet having an adhesive layer (Y) having all the following characteristics (1) to (3) is proposed.
(1) The gel fraction (gel fraction before light irradiation X1) is in the range of 0 to 60%.
(2) The light transmittance at a wavelength of 390 nm is 89% or less, and the light transmittance at a wavelength of 410 nm is 80% or more.
(3) It has photocurability that is cured by irradiation with light having a wavelength of 405 nm.

The photocurable pressure-sensitive adhesive sheet proposed by the present invention has a gel fraction before photocuring of 0 to 60%, so that it is possible to obtain a step absorbability to fill a step such as irregularities on the adherend surface, while a wavelength of 390 nm. The light transmittance at 89 nm is 89% or less and the resin member (X) to be bonded has a light transmittance at a wavelength of 365 nm of 10 because it is cured by irradiation with light having a wavelength of 405 nm. %, And even when the light transmittance at a wavelength of 405 nm is 60% or more, it can be cured by irradiation with light containing a wavelength of 405 nm, and the cohesive strength is increased to increase the foaming resistance reliability after bonding. Can be obtained.
Moreover, since the light-curing pressure-sensitive adhesive sheet proposed by the present invention has a light transmittance at a wavelength of 410 nm of 80% or more, it has a sufficiently low yellowness necessary for bonding optical members that require transparency ( YI) can be achieved.

  Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to such an embodiment.

<< This adhesive sheet >>
The pressure-sensitive adhesive sheet (referred to as “the present pressure-sensitive adhesive sheet”) according to an example of the embodiment of the present invention is a photocurable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (Y) having predetermined characteristics.

This pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet having photocurability that is cured by irradiation with light. At this time, the pressure-sensitive adhesive sheet may be cured (also referred to as “temporary curing”) in a state in which there is room for photocuring, is not yet cured, and has photocurability. It may be uncured (referred to as “uncured”).
If the pressure-sensitive adhesive sheet is temporarily cured or uncured, the pressure-sensitive adhesive sheet can be light-cured (also referred to as “main-curing”) after the pressure-sensitive adhesive sheet is bonded to an adherend. As a result, the cohesive force can be increased and the adhesiveness can be increased.

  As a preferable form of the present pressure-sensitive adhesive sheet having the above-mentioned temporarily cured or uncured property and capable of being fully cured, that is, photocurability that is cured by irradiation with light having a wavelength of 405 nm, The adhesive sheet which has the adhesion layer (Y) shown to (1)-(3) can be mentioned.

(1) The pressure-sensitive adhesive layer (Y) is temporarily cured so that the gel fraction is 60% or less, and contains the visible light initiator (c) described below, whereby the visible light initiator (c) is used. It is a pressure-sensitive adhesive layer that can be fully cured.
(2) The pressure-sensitive adhesive layer (Y) is temporarily cured so that the gel fraction becomes 60% or less by the hydrogen drawing type visible light initiator (c-2) of the visible light initiator (c) described below. And a pressure-sensitive adhesive layer capable of main curing with the visible light initiator (c-2).
(3) The pressure-sensitive adhesive layer (Y) retains the sheet shape as it is uncured and contains the visible light initiator (c) described below, so that the main curing with the visible light initiator (c) is possible. It is an adhesive layer.

Examples of the method for forming the adhesive layer (Y) of (1) above include a visible light initiator (c), a (meth) acrylic acid ester (co) polymer (a) having a functional group (i), Crosslinkers (b) such as a compound having a functional group (ii) that reacts with the functional group (i) and, if necessary, a photopolymerizable compound having a carbon-carbon double bond (particularly a polyfunctional monomer). And a method of forming an adhesive layer (Y) by heating or curing a composition (an example of the present resin composition to be described later) containing a silane coupling agent (d)) as necessary. it can.
According to this method, the functional group (i) in the (meth) acrylic acid ester (co) polymer reacts with the functional group (ii) in the compound to form a chemical bond. Curing (crosslinking) forms an adhesive layer (Y). By forming the adhesive layer (Y) in this manner, the visible light initiator (c) can be present in the adhesive layer (Y) while having activity.

  Examples of the combination of the functional group (i) and the functional group (ii) include a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, a hydroxyl group and an isocyanate group, an amino group and an isocyanate group, and a carboxyl group and an isocyanate group. be able to. Among these, a combination of a hydroxyl group and an isocyanate group, an amino group and an isocyanate group, or a carboxyl group and an isocyanate group is particularly preferable. More specifically, a particularly preferred example is a case where the (meth) acrylic acid ester copolymer (a) has a hydroxyl group (using a hydroxyl group-containing monomer described below) and the compound has an isocyanate group. It is.

The compound having the functional group (ii) may further have a radical polymerizable functional group such as a (meth) acryloyl group. Thereby, the light of the (meth) acrylic acid ester (co) polymer by the radical polymerizable functional group, specifically, the (meth) acrylic acid ester copolymer having the active energy ray crosslinkable structure site described below. The adhesive layer (Y) can be formed while maintaining the curing (crosslinking) property. More specifically, when the (meth) acrylic acid ester (co) polymer (a) has a hydroxyl group (using a hydroxyl group-containing monomer described below) and the compound has a (meth) acryloyl group. (2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, etc.) are particularly suitable examples.
Thus, by utilizing the crosslinking reaction between (meth) acrylic acid ester (co) polymers by the radical polymerizable functional group, the cohesive force after photocuring (crosslinking) without using the crosslinking agent (b). Is more preferable because it has an advantage of being easily raised efficiently and having excellent reliability.

  In addition, about preferable forms of the acrylic ester (co) polymer (a), the crosslinking agent (b), the visible light initiator (c), and the silane coupling agent (d) other than the above, etc. Is described below.

Examples of the method for forming the pressure-sensitive adhesive layer (Y) in (2) include a method using a hydrogen abstraction type visible light initiator (c-2) described below as the visible light initiator (c). it can. The hydrogen abstraction-type disclosure agent can be used again as a visible light initiator because even if it is excited once, the initiator that has not reacted returns to the ground state. As described above, by using a hydrogen abstraction type visible light initiator, visible light curing (crosslinking) property by the visible light initiator can be maintained even after temporary curing by visible light irradiation.
In addition, the points other than the above and preferred forms of the visible light initiator (c-2) are described below.

Examples of the method for forming the pressure-sensitive adhesive layer (Y) in (3) above include a method using a macromonomer described below as a monomer component constituting the (meth) acrylic acid ester copolymer (a). . More specifically, a method using a graft copolymer having a macromonomer as a branch component can be mentioned. By using such a macromonomer, it is possible to maintain a state in which branch components are attracted to each other and physically crosslinked as a composition (an example of the resin composition described later) at room temperature.
Accordingly, the sheet shape can be maintained while remaining uncured (crosslinked), and the adhesive layer (Y) containing the visible light initiator (c) can be formed.
In addition, the points other than the above and preferred forms of the graft copolymer having a macromonomer as a branch component are described below.

  It is preferable to use this adhesive sheet in order to bond resin member (X) mentioned later.

  The pressure-sensitive adhesive sheet may have a single-layer structure of the pressure-sensitive adhesive layer (Y) or a multilayer structure of two or more layers having the pressure-sensitive adhesive layer (Y). In the case of multiple layers, at least the outermost layer may be the adhesive layer (Y), and all the adhesive layers may be the adhesive layer (Y).

<Adhesive layer (Y)>
The adhesive layer (Y) preferably has all the following properties (1) to (3).
(1) The gel fraction in a normal state, that is, a state before light irradiation (referred to as “gel fraction before light irradiation X1”) is in the range of 0 to 60%.
(2) The light transmittance at a wavelength of 390 nm is 89% or less, and the light transmittance at a wavelength of 410 nm is 80% or more.
(3) It has photocurability that is cured by irradiation with light having a wavelength of 405 nm.

If the pressure-sensitive adhesive layer (Y) has a hot melt property that softens or flows when heated, if there is a step such as unevenness on the adherend surface of the bonding member, the pressure-sensitive adhesive can be more easily applied to every corner of the step. It is preferable because the step absorbability can be further increased.
From this point of view, the pressure-sensitive adhesive layer (Y) is preferably the pressure-sensitive adhesive layer (Y) of (3) above.

(Gel fraction)
The gel fraction (gel fraction before light irradiation X1) of the adhesive layer (Y) is preferably in the range of 0 to 60%.
If the gel fraction of the pressure-sensitive adhesive layer (Y) is 60% or less, there are sufficiently many uncrosslinked components that can be cured by light irradiation (in a temporarily cured state or in an uncured state), and that is flexible. And in the case of this hardening, it is preferable from a viewpoint which can make "gel fraction after light irradiation X2-gel fraction before light irradiation X1" 10% or more.
From this viewpoint, the gel fraction of the pressure-sensitive adhesive layer (Y) is preferably in the range of 0 to 60%, more preferably 55% or less, and most preferably 50% or less.

  In order to adjust the gel fraction (gel fraction before light irradiation X1) of the pressure-sensitive adhesive layer (Y) to the above range, the residual catalyst is sufficiently removed during polymerization of the resin composition and processing of the pressure-sensitive adhesive sheet, which will be described later, or It is only necessary to prevent unintended curing (crosslinking) reaction by heat, light, etc. before the main curing by using a polymerization inhibitor or antioxidant. The accumulated light amount of light irradiated for temporary curing may be sufficiently reduced so that the amount of uncrosslinked components is sufficiently increased. However, it is not limited to this method.

Furthermore, the pressure-sensitive adhesive layer (Y) preferably has photocurability that is cured by irradiation with light having a wavelength of 405 nm. The degree of photocurability is, for example, from the outside of the resin member (X). Photo-curing that increases by 10% or more, especially 15% or more, especially 20% or more, especially 30% or more, especially 50% or more as a difference in gel fraction when irradiated with light having a wavelength of 405 nm via (X) It is preferable to have the property.
Note that “irradiate light with a wavelength of 405 nm” means to irradiate light having photosensitivity, which is measured using an ultraviolet light quantity meter, with a wavelength of 405 nm as a photosensitive peak, and the base is expanded to a wavelength range of 320 to 470 nm. Means.

Among these, when the adhesive layer (Y) is irradiated with light having an integrated light amount of 3000 (mJ / cm ² ) at a wavelength of 405 nm from the outside of the resin member (X), for example, via the resin member (X). The difference (gel fraction after light irradiation X2−) between the gel fraction before light irradiation (gel fraction before light irradiation X1) and the gel fraction after light irradiation (referred to as “gel fraction after light irradiation X2”). It is preferable to have photocurability that the gel fraction X1) before light irradiation is 10% or more.
Therefore, for example, when the gel fraction X1 before light irradiation is 40%, the gel fraction of the adhesive layer (Y) after irradiation with light having an integrated light amount of 3000 (mJ / cm ² ) at a wavelength of 405 nm (“ It is preferable to have photocurability such that the gel fraction after light irradiation X2 "is 50% or more.
A difference in gel fraction of the pressure-sensitive adhesive layer (Y) before and after photocuring of 10% or more is preferable because it has a high cohesive force even in a severe high temperature and high humidity environment and can improve foaming reliability.
Therefore, the difference in gel fraction of the pressure-sensitive adhesive layer (Y) before and after the light irradiation is preferably 10% or more, especially 15% or more, especially 20% or more, especially 30% or more, and especially 50% or more. Is more preferable.
In order to adjust the difference in gel fraction of the pressure-sensitive adhesive layer (Y) before and after the light irradiation to be in the above range, it is sufficient that the wavelength 405 nm is absorbed by the photoinitiator. However, it is not limited to this method.

  The “integrated light amount at a wavelength of 405 nm” is the total amount of irradiation energy received per unit area. Of the light irradiated by a high-pressure mercury lamp or the like, an ultraviolet integrated light meter “UIT-250” (USHIO Inc.) This refers to the total amount of light irradiation energy measured using a photoreceiver “UVD-C405” (manufactured by USHIO INC.), And the photosensitivity of the photoreceiver (wavelength range of 320 to 470 nm with 405 nm as the photosensitivity peak) It indicates the integrated light quantity in the wavelength range according to the photosensitivity of which the base is widened. More specifically, it refers to the integrated light amount obtained in accordance with the method described in the examples.

(Light transmittance)
The adhesive layer (Y) preferably has a light transmittance of 89% or less at a wavelength of 390 nm and a light transmittance of 80% or more at a wavelength of 410 nm.
For a pressure-sensitive adhesive composition in which a photoinitiator having absorption in the ultraviolet to visible light region having a wavelength of around 400 nm is blended, the light absorption of the photoinitiator is large, and the light transmittance at a wavelength of 390 nm derived from the absorption is low. It has good photosensitivity and cures easily.
On the other hand, if the light transmittance at a wavelength of 410 nm is not higher than a certain level, the pressure-sensitive adhesive layer (Y) is colored yellow, making it difficult to use it for an optical member.

As a guideline above, if the light transmittance at a wavelength of 390 nm is 89% or less, the adhesive layer (Y) is preferable because it can ensure sufficient visible light curability, and the light transmittance at a wavelength of 410 nm is 80% or more. If so, it is preferable because a sufficiently low yellowness (YI) necessary for bonding optical members requiring transparency can be achieved.
Accordingly, the adhesive layer (Y) preferably has a light transmittance of 89% or less at a wavelength of 390 nm, more preferably 88% or less.
Further, the light transmittance at a wavelength of 410 nm is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more.
In order to make the light transmittance of the adhesive layer (Y) as described above, among the initiators that absorb visible light, the base of the absorption peak reaches sufficiently up to 390 nm, whereas the absorption peak at 410 nm has an absorption peak. What has a small absorption peak characteristic may be used. However, it is not limited to this method.

(Storage modulus)
The storage elastic modulus (G ′) of the adhesive layer (Y) is preferably 0.9 × 10 ⁵ Pa or less at a temperature of 25 ° C. and a frequency of 1 Hz.
By having such viscoelastic properties, the pressure-sensitive adhesive sheet can obtain a step absorbability particularly excellent for filling a step such as unevenness on the adherend surface.
From this viewpoint, the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer (Y) is preferably 0.9 × 10 ⁵ Pa or less, particularly 0.8 × 10 ⁵ Pa or less, at a temperature of 25 ° C. and a frequency of 1 Hz. More preferably.

The adhesive layer (Y) also has a storage elastic modulus (G ′) after irradiation with light having an integrated light quantity of 3000 (mJ / cm ² ) at a wavelength of 405 nm of 0.7 at a temperature of 120 ° C. and a frequency of 1 Hz. It is preferably x 10 ⁴ Pa or more.
When the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer (Y) after photocuring is in the above range, when the laminate with the resin member (X) is subjected to a high temperature test, a high temperature high humidity test, etc., the resin member It is preferable at the point which can suppress that the adhesion layer (Y) foams with the outgas component from (X).
From this viewpoint, the storage elastic modulus (G ′) of the pressure-sensitive adhesive layer (Y) after photocuring is preferably 0.7 × 10 ⁴ Pa or more at a temperature of 120 ° C. and a frequency of 1 Hz, and more preferably 1.0 × 10 ⁴ Pa or more is more preferable, and among them, 2.0 × 10 ⁴ Pa or more is more preferable.

By the way, in an image display device having a touch panel function, as a touch sensor disposed on the back side of the front panel / adhesive layer, a glass sensor, a film sensor, a polarizing plate glass (on-cell type or in-cell type in which the sensor is incorporated) Etc. are properly used depending on the module design, and the probability of occurrence of defects in the environmental test differs depending on the configuration of the sensor member.
As a result of the experimental investigation in the present invention, when the adhesive layer (Y) is used in a configuration of resin member (X) / adhesive layer (Y) / glass sensor, the storage elastic modulus of the adhesive layer (Y) ( While the preferred range of G ′) is as described above, when the laminate is used in the configuration of resin member (X) / adhesive layer (Y) / film sensor, the film sensor is usually thin with a thickness of 100 μm or less. Since the rigidity improvement effect is low and the reliability improvement effect of the silane coupling agent is lower than the reliability improvement effect of the glass material, foaming is more likely to occur than in the case of the glass sensor in the wet heat environment test, and a higher level of storage elastic modulus. (G ′) is required.

Therefore, this viewpoint, that is, the storage elasticity of the pressure-sensitive adhesive layer (Y) after photocuring when the pressure-sensitive adhesive layer (Y) is bonded and used in the configuration of resin member (X) / pressure-sensitive adhesive layer (Y) / film sensor. The preferable range of the storage elastic modulus (G ′) of the adhesive layer (Y) when irradiated with light having a rate (G ′), that is, an integrated light amount of 3000 (mJ / cm ² ) at a wavelength of 405 nm is 2 0.0 × 10 ⁴ Pa or more, more preferably 5.0 × 10 ⁴ Pa or more, and even more preferably 8.0 × 10 ⁴ Pa or more.

(Composition of adhesive layer (Y))
The adhesive layer (Y) comprises a (meth) acrylic acid ester (co) polymer (a) and a visible light initiator (c), further a crosslinking agent (b) if necessary, and further a silane coupling agent if necessary. (D) It can be formed from a pressure-sensitive adhesive composition (referred to as “the present resin composition”) containing other materials as required.

[(Meth) acrylic acid ester (co) polymer (a)]
The (meth) acrylic acid ester (co) polymer (a) is preferably photocurable.

  “(Meth) acryl” means acryl and methacryl, “(meth) acryloyl” means acryloyl and methacryloyl, and “(meth) acrylate” includes acrylate and methacrylate, respectively. It is. The term “(co) polymer” includes a polymer and a copolymer. The “sheet” conceptually includes a sheet, a film, and a tape.

  Examples of the (meth) acrylic acid ester (co) polymer (a) include, for example, a copolymer obtained by polymerizing a monomer component copolymerizable with an alkyl (meth) acrylate homopolymer. Can be mentioned. For example, the copolymer obtained by superposing | polymerizing the monomer component copolymerizable with this besides the homopolymer of an alkyl (meth) acrylate can be mentioned.

  More specifically, as the (meth) acrylic acid ester (co) polymer (a), alkyl (meth) acrylate and a monomer component copolymerizable therewith, such as (a) a carboxyl group-containing monomer (hereinafter referred to as “ Copolymerizable monomer A "), (b) hydroxyl group-containing monomer (hereinafter also referred to as" copolymerizable monomer B "), and (c) amino group-containing monomer (hereinafter also referred to as" copolymerizable monomer C "). ), (D) epoxy group-containing monomer (hereinafter also referred to as “copolymerizable monomer D”), (e) amide group-containing monomer (hereinafter also referred to as “copolymerizable monomer E”), (f) vinyl monomer ( (Hereinafter also referred to as “copolymerizable monomer F”), (g) a (meth) acrylate monomer having 1 to 3 carbon atoms in the side chain (hereinafter also referred to as “copolymerizable monomer G”) and ( ) Macromonomer (hereinafter also referred to as "copolymerizable monomer H".) Can be mentioned a copolymer of a monomer component containing one or more monomers selected from.

The alkyl (meth) acrylate is preferably a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain.
Examples of the linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n- Octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) Acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate 3,5,5-trimethylcyclohexane (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Among the above, as a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms, any of butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and isobornyl (meth) acrylate It is particularly preferred to include one or more.

  Examples of the copolymerizable monomer A include (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, and 2- (meth) acryloyloxyethyl. Phthalic acid, 2- (meth) acryloyloxypropyl phthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- ( Mention may be made of (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid. These may be used alone or in combination of two or more.

  Examples of the copolymerizable monomer B include hydroxyalkyl (2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate) and the like. Mention may be made of (meth) acrylates. These may be used alone or in combination of two or more.

  Examples of the copolymerizable monomer C include aminoalkyl (meth) acrylates such as aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, aminoisopropyl (meth) acrylate, and N-alkylamino. Mention may be made of N, N-dialkylaminoalkyl (meth) acrylates such as alkyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like. These may be used alone or in combination of two or more.

  Examples of the copolymerizable monomer D include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether. . These may be used alone or in combination of two or more.

  Examples of the copolymerizable monomer E include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, Examples thereof include N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, maleic acid amide, and maleimide. These may be used alone or in combination of two or more.

Examples of the copolymerizable monomer F include compounds having a vinyl group in the molecule. Examples of such compounds include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms, and functional monomers having a functional group such as a hydroxyl group, an amide group and an alkoxylalkyl group in the molecule; Polyalkylene glycol di (meth) acrylates and vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl laurate, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and other substituted styrenes Can be illustrated. These may be used alone or in combination of two or more.
Among these, it is preferable to select the alkyl (meth) acrylate and the copolymerizable monomer F other than the alkyl (meth) acrylate.

Examples of the copolymerizable monomer G include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Among these, it is preferable to select the alkyl (meth) acrylate and the copolymerizable monomer G other than the alkyl (meth) acrylate.

  The macromonomer as the copolymerizable monomer H is a polymer monomer having a terminal functional group and a high-molecular-weight skeleton component, and a side chain when a (meth) acrylate copolymer is obtained by polymerization. A monomer having a carbon number of 20 or more is preferable.

By using the copolymerizable monomer H, a macromonomer can be introduced as a branch component of the graft copolymer, and the (meth) acrylic acid ester copolymer can be used as the graft copolymer. For example, it can be set as the (meth) acrylic acid ester copolymer (a-1) which consists of a graft copolymer provided with the macromonomer as a branch component.
Therefore, the characteristics of the main chain and side chain of the graft copolymer can be changed depending on the selection and blending ratio of the copolymerizable monomer H and other monomers.

  The skeleton component of the macromonomer is preferably composed of an acrylate polymer or a vinyl polymer. Examples include linear or branched alkyl (meth) acrylates having 4 to 18 carbon atoms in the side chain, the copolymerizable monomer A, the copolymerizable monomer B, and the copolymerizable monomer G. These may be used alone or in combination of two or more.

  Among them, the main component of the (meth) acrylic acid ester copolymer (a-1) contains a hydrophobic (meth) acrylic acid ester and a hydrophilic (meth) acrylic acid ester as structural units. preferable.

As said hydrophobic (meth) acrylic acid ester, the alkyl ester which does not have a polar group (however, except methyl acrylate) is preferable, for example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec- Butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate Rate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate Cyclohexyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and methyl methacrylate.
Examples of the hydrophobic vinyl monomer include vinyl acetate, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, and alkyl vinyl monomers.

  On the other hand, as the hydrophilic (meth) acrylate monomer, methyl acrylate and esters having a polar group are preferable. For example, methyl acrylate, (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, and hydroxyethyl (meth). Hydroxyl group-containing (meth) acrylates such as acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethylmalein 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, Carboxyl group-containing monomers such as monomethyl itaconic acid, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, 3,4-epoxy (meth) acrylic acid Mention may be made of epoxy group-containing monomers such as butyl, alkoxypolyalkylene glycol (meth) acrylates such as methoxypolyethylene glycol (meth) acrylate, N, N-dimethylacrylamide, hydroxyethylacrylamide and the like.

The macromonomer as the copolymerizable monomer H preferably has a functional group such as a radical polymerizable group, hydroxyl group, isocyanate group, epoxy group, carboxyl group, amino group, amide group or thiol group. .
As said macromonomer, what has a radically polymerizable group copolymerizable with another monomer is preferable. One or two or more radically polymerizable groups may be contained, and one of them is particularly preferred.
When the macromonomer has a functional group, one or two or more functional groups may be contained, and one of them is particularly preferable.
Further, either one of the radical polymerizable group and the functional group may be contained. When both radically polymerizable group and functional group are contained, the functional group or radical polymerization other than either the functional group to be added to the polymer unit composed of other monomers or the radical polymerizable group to be copolymerized with other monomers Two or more sex groups may be present.

Examples of the terminal functional group of the macromonomer include radical polymerization groups such as methacryloyl group, acryloyl group, and vinyl group, hydroxyl group, isocyanate group, epoxy group, carboxyl group, amino group, amide group, thiol group, and the like. Mention may be made of functional groups.
Among these, those having a radical polymerizable group copolymerizable with other monomers are preferable. One or two or more radically polymerizable groups may be contained, and one of them is particularly preferred. Even when the macromonomer has a functional group, one or two or more functional groups may be contained, and one of them is particularly preferable.
Moreover, the radical polymerizable group and the functional group may contain either one or both. In the case of containing both a radical polymerizable group and a functional group, a functional group or radical polymerization other than either a functional group to be added to a polymer unit composed of another monomer or a radical polymerizable group to be copolymerized with another monomer Two or more sex groups may be present.

  The number average molecular weight of the macromonomer is preferably 500 to 20,000, more preferably 800 or more and 8000 or less, and particularly preferably 1000 or more and 7000 or less.

The glass transition temperature (Tg) of the macromonomer is preferably higher than the glass transition temperature of the copolymer component constituting the (meth) acrylic acid ester (co) polymer (a-1).
Specifically, since the glass transition temperature (Tg) of the macromonomer affects the heating and melting temperature (hot melt temperature) of the pressure-sensitive adhesive sheet, it is preferably 30 ° C to 120 ° C. More preferably, the temperature is 50 ° C. or lower, more preferably 50 ° C. or higher or 100 ° C. or lower.

If the macromonomer is such a glass transition temperature (Tg), it is possible to maintain excellent processability and storage stability by adjusting the molecular weight, and to adjust to hot melt at around 50 ° C to 80 ° C. be able to.
The glass transition temperature of the macromonomer means the glass transition temperature of the macromonomer itself and can be measured with a differential scanning calorimeter (DSC).

  Further, at room temperature, the branch components are attracted to each other and can maintain a state where they are physically cross-linked as a pressure-sensitive adhesive composition, and the physical cross-linking is released by heating to an appropriate temperature. In order to obtain fluidity, it is also preferable to adjust the molecular weight and content of the macromonomer.

From such a viewpoint, the macromonomer is preferably contained in the (meth) acrylic acid ester copolymer (a) in a proportion of 5% by mass to 30% by mass, among which 6% by mass or more or 25% by mass or less. Among these, it is more preferable to contain at a ratio of 8% by mass or more or 20% by mass or less.
The number average molecular weight of the macromonomer is preferably 500 to 100,000, more preferably less than 8000, more preferably 800 or more and less than 7500, and particularly preferably 1000 or more and less than 7000.

The (meth) acrylic acid ester (co) polymer (a) preferably has an active energy ray crosslinkable structure moiety.
The active energy ray crosslinkable structure means, for example, a part of the (meth) acrylate copolymer (a) or (meth) acrylate ester copolymer in the presence of a visible light initiator (c) described later. It is a structural site that can react with a curing component other than the coalescence (a) to form a crosslinked structure.

As said active energy ray crosslinkable structure site | part, the structure which has a radically polymerizable functional group which has carbon-carbon double bonds, such as a functional group which has unsaturated double bonds, such as a (meth) acryloyl group and a vinyl group, for example. Can be mentioned.
The polymer chain of the (meth) acrylic acid ester (co) polymer (a) has an unsaturated double bond, so that the polymer chains can be directly polymerized even if they do not contain a crosslinking agent. The storage elastic modulus (G ′) can be raised to a high level.
In addition, when irradiating active energy rays, an arbitrary light source containing light having a wavelength of 405 nm may be used, and a visible light LED light source, high-pressure mercury is used from the viewpoint of curing speed, availability of an irradiation device, price, and the like. A lamp or the like can be used.

  In order to introduce a structure having a radical polymerizable functional group having a carbon-carbon double bond such as a functional group having an unsaturated double bond, for example, the (meth) acrylic acid ester (co) polymer (a) is previously used. After a monomer having a functional group is copolymerized, a functional group capable of reacting with this functional group (for example, 2-isocyanatoethyl (meth) acrylate) and a carbon-carbon doubler such as a monomer having an unsaturated double bond A compound having a bond may be reacted while maintaining the curability of the carbon-carbon double bond.

Among them, the (meth) acrylic acid ester copolymer (a) includes a (meth) acrylic acid ester monomer having an active energy ray crosslinkable structure portion and having a linear alkyl group having 10 to 24 carbon atoms. The monomer component is preferably a (meth) acrylic acid ester (co) polymer (a-2).
As such a (meth) acrylic acid ester (co) polymer (a-2), for example, decyl (meth) acrylate (alkyl group having 10 carbon atoms), lauryl (meth) acrylate (carbon number 12), tridecyl ( Examples include meth) acrylate (carbon number 13), hexadecyl (meth) acrylate (carbon number 16), stearyl (meth) acrylate (carbon number 18), and behenyl (meth) acrylate (carbon number 22). These may be used alone or in combination of two or more.

  In addition, among the linear (meth) acrylic acid alkyl ester monomers (a) having an alkyl group having 10 to 24 carbon atoms, it is possible to lower the dielectric constant and lower the glass transition temperature of the acrylic resin. Alkyl methacrylate is preferably used, particularly preferably one having an alkyl group having 12 to 20 carbon atoms, and most preferably stearyl methacrylate, lauryl methacrylate, or tridecyl methacrylate.

  The content of the (meth) acrylic acid alkyl ester monomer (a) having a linear alkyl group having 10 to 24 carbon atoms is 50 to 94% by weight, preferably 60 to 94% by weight based on the entire (co) polymerization component. 83% by weight, particularly preferably 70 to 80% by weight. By setting it within the above range, there is no possibility that the dielectric constant increases or the thermal stability of the resin decreases.

[Crosslinking agent (b)]
The crosslinking agent (b) is preferably a crosslinking agent having at least double bond crosslinking. For example, at least one crosslinkable functional group selected from (meth) acryloyl group, epoxy group, isocyanate group, carboxyl group, hydroxyl group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group and amide group The crosslinking agent which has can be mentioned, You may use combining 1 type (s) or 2 or more types.
In particular, by using two or more kinds of crosslinking agents in combination, a high storage elastic modulus (G ′) can be achieved even when the total amount is the same as compared with the case where each is used alone.
Therefore, it is more preferable to use a combination of two or more kinds of crosslinking agents (b).
Further, an embodiment in which the crosslinking agent (b) is chemically bonded to the (meth) acrylic acid ester (co) polymer (a) is also included.

Among these, it is preferable to use a photopolymerizable compound having a carbon-carbon double bond, especially a polyfunctional (meth) acrylate. Here, polyfunctional means what has two or more crosslinkable functional groups. In addition, you may have 3 or more and 4 or more crosslinkable functional groups as needed.
The crosslinkable functional group may be protected with a deprotectable protecting group.

  Examples of the polyfunctional (meth) acrylate include 1,4-butanediol di (meth) acrylate, glycerin di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin glycidyl ether di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A poly Propoxy di (meth) acrylate, bisphenol F polyethoxy di (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylol group Pantrioxyethyl (meth) acrylate, ε-caprolactone modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol Tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyethylene glycol di (meth) acrylate , Tris (acryloxyethyl) isocyanurate, dipentaerythritol hexa (meth) acrylate, dipentaery Ε-caprolactone adducts of ritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxybivalate, neopentyl hydroxybivalate Of UV-curable polyfunctional (meth) acrylic monomers such as di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane polyethoxytri (meth) acrylate, and ditrimethylolpropane tetra (meth) acrylate In addition, polyfunctional (meth) acrylic acrylic such as polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, etc. Goma can be mentioned. These may be used alone or in combination of two or more.

Among the polyfunctional (meth) acrylates described above, from the viewpoint of imparting high cohesive force, those having a short cross-link point distance in the formed cross-linked structure and a dense cross-link density are preferable. Modified trifunctional or higher polyfunctional (meth) acrylate is preferable, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Pentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tet (Meth) polyfunctional (meth) acrylate is selected from the group consisting of acrylate (b-1) is preferable.
The polyfunctional (meth) acrylate (b-1) may be used alone or in combination of two or more (as a mixture).

Moreover, when using the said polyfunctional (meth) acrylate (b-1) as a crosslinking agent, the said (meth) acrylic acid ester (a) uses a hydrophilic monomer as a polar component from a compatible viewpoint. The copolymer of the monomer component to contain is preferable.
When the (meth) acrylic acid ester (a) contains a polar component, the compatibility with the polyfunctional (meth) acrylate (b-1) is improved, it is easy to mix during mixing, and it is long in an uncrosslinked state. It is difficult for phase separation to occur when stored for a long time, and there is no possibility that the haze value will rise.

Specifically, as the (meth) acrylic acid ester (co) polymer (a), the above-mentioned alkyl (meth) acrylate and the above-mentioned copolymerizable monomer as a copolymerizable monomer copolymerizable therewith are used. A monomer component containing a methyl (meth) acrylate selected from the above-mentioned hydrophilic (meth) acrylic acid ester or at least the copolymerizable monomer G, among which a hydrophilic monomer is appropriately selected from A to G It is preferable that it is a copolymer.
Further, the (meth) acrylic acid ester (co) polymer (a) contains at least methyl (meth) acrylate, and the total of hydrophilic monomers (selected from copolymerizable monomers A to G). It is particularly preferable that the monomer component copolymer accounts for 10 parts by mass or more of the entire (meth) acrylic acid ester (co) polymer (a).

  In addition, the said (meth) acrylic acid ester (co) polymer (a-1) is a linear or branched alkyl (meth) acrylate whose carbon number of the side chain mentioned above is 4-18 as a frame | skeleton component (trunk component). And a copolymer of monomer components containing the hydrophilic monomer as a copolymerizable monomer copolymerizable therewith.

  Content of a crosslinking agent (b) is 0.5-50 mass parts with respect to 100 mass parts of said (meth) acrylic acid ester (co) polymers (a), Especially 1 mass part or more or 40 mass parts or less, Among them, the ratio is preferably 5 parts by mass or more or 30 parts by mass or less.

[Visible light initiator (c)]
The visible light initiator (c) generates a radical by irradiation with visible light, light having a wavelength of at least 390 nm, 405 nm, and 410 nm, for example, light in the wavelength region of 380 nm to 700 nm, and (meth) acrylic acid ester (co-polymer). It is preferable that the visible light initiator be a starting point for the reaction of the polymer (a).
However, the visible light initiator (c) may generate radicals only by irradiation with visible light, or it may generate radicals by irradiation with light in a wavelength region other than the visible light region. There may be.

The visible light initiator (c) preferably has an extinction coefficient at a wavelength of 405 nm of 10 mL / (g · / cm) or more, more preferably 15 mL / (g · / cm) or more, and more preferably 25 mL / (g · / cm). cm) or more. When the extinction coefficient at a wavelength of 405 nm is 10 mL / (g · / cm) or more, curing (crosslinking) by irradiation with visible light can sufficiently proceed.
On the other hand, the upper limit of the extinction coefficient at a wavelength of 405 nm is preferably 1 × 10 ⁴ mL / (g · / cm) or less, and more preferably 1 × 10 ³ mL / (g · / cm) or less. preferable. In addition, you may use together with the photoinitiator whose extinction coefficient in wavelength 405nm is less than 10 mL / (g * / cm).

  Photoinitiators are broadly classified into two types depending on the radical generation mechanism, a cleavage type photoinitiator that can cleave and decompose a single bond of the photoinitiator itself to generate a radical, a photoexcited initiator, and a photoinitiator in the system. It is roughly classified into a hydrogen abstraction type photoinitiator that can form an exciplex with a hydrogen donor and transfer hydrogen of the hydrogen donor.

Of these, the cleavage type photoinitiator decomposes into another compound when generating radicals by light irradiation, and once excited, it does not function as a reaction initiator. For this reason, it does not remain as an active species in the pressure-sensitive adhesive after completion of the cross-linking reaction, and it is not likely to cause unexpected light degradation or the like in the pressure-sensitive adhesive, which is preferable.
Moreover, about coloring specific to a photoinitiator, conventionally, when a cleavage type visible light initiator (c-1), which is cured by irradiating an adhesive with visible light, is added, there is a risk of coloring. Therefore, as the visible light initiator (c), it is preferable to appropriately select a visible light initiator that loses absorption in the visible light region and is decolored.
On the other hand, the hydrogen abstraction type photoinitiator can maintain its function as a reaction initiator even when irradiated multiple times, and it also initiates cleavage type photoinitiation during radical generation reaction by irradiation with active energy rays such as ultraviolet rays. Since no decomposition product such as an agent is generated, it is difficult to become a volatile component after completion of the reaction, which is useful in that damage to the adherend can be reduced.
Therefore, a hydrogen abstraction type visible light polymerization initiator (c-2) that is excited by visible light and starts polymerization is particularly preferable.

Examples of the cleavage type visible light initiator (c-1) include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1- Phenyl-propan-1-one, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- [4- {4- (2-Hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone ), Methyl phenylglyoxylic acid, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [ -(Methylthio) phenyl] -2-morpholinopropan-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl) -1- [4- (4-morpholinyl) phenyl] -1 -Butanone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, and And derivatives thereof.
Among these, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6) in that it decomposes and disappears after the reaction. Acylphosphine oxide photoinitiators such as -trimethylbenzoyl) ethoxyphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide are preferred.

Examples of the hydrogen abstraction type visible light initiator (c-2) include bis (2-phenyl-2-oxoacetic acid) oxybisethylene, phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2- [ A mixture of 2-oxo-2-phenyl-acetoxy-ethoxy] ethyl ester and oxy-phenyl-acetic acid 2- [2-hydroxy-ethoxy] ethyl ester, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2, Examples thereof include 4-dimethylthioxanthone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, camphorquinone and derivatives thereof.
Among these, phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2- [2-oxo-2-phenyl-acetoxy-ethoxy] ethyl ester and oxy-phenyl-acetic acid 2- [2-hydroxy- It is preferably any one or two selected from the group consisting of a mixture of ethoxy] ethyl esters.

The visible light initiator (c) is not limited to the substances listed above. Any one of the visible light initiators (c) listed above or a derivative thereof may be used, or two or more thereof may be used in combination.
Moreover, you may mix the thing which generate | occur | produces a radical only by irradiation of other light rays, such as an ultraviolet-ray, besides visible light initiator (c).

The content of the visible light initiator (c) is not particularly limited. 0.1 to 10 parts by weight, particularly 0.5 parts by weight or more or 5 parts by weight or less, with respect to 100 parts by weight of the (meth) acrylic acid ester (co) polymer (a) in the adhesive layer (Y). It is preferably contained in a proportion of 1 part by mass or more or 3 parts by mass or less.
By setting the content of the visible light initiator (c) in the above range, an appropriate reaction sensitivity to visible light can be obtained.

[Silane coupling agent (d)]
The silane coupling agent (d) can improve the adhesiveness, and in particular, the adhesive force to the glass material.
Examples of the silane coupling agent include compounds having a hydrolyzable functional group such as an alkoxy group together with an unsaturated group such as a vinyl group, an acryloxy group, and a methacryloxy group, an amino group, and an epoxy group. .
Specific examples of the silane coupling agent include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.
Among them, in the adhesive layer (Y), γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane is preferable from the viewpoint of good adhesion and less discoloration such as yellowing. Can be used.
The said silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

It is preferable that content of the said silane coupling agent (d) is 0.1-5 mass parts with respect to 100 mass parts of adhesion layers (Y), and 0.2 mass part or more or 3.0 mass parts or less especially. More preferably.
Similar to the silane coupling agent, a coupling agent such as an organic titanate compound can also be used effectively.

[Other materials]
Components other than the above contained in the resin composition forming the adhesive layer (Y) include, for example, light stabilizers, ultraviolet absorbers, metal deactivators, metal corrosion inhibitors, anti-aging agents, and antistatic agents. Agents, hygroscopic agents, foaming agents, antifoaming agents, inorganic particles, viscosity modifiers, tackifier resins, photosensitizers, fluorescent agents, and other additives, reaction catalysts (tertiary amine compounds, quaternary ammonium compounds) Compound, tin laurate compound, etc.).
Moreover, you may contain suitably the well-known component mix | blended with a normal adhesive composition.
Moreover, you may use 2 or more types of each component together.

  Among these, it is preferable that especially this resin composition which forms the adhesion layer (Y) contains a ultraviolet absorber. As described above, since the pressure-sensitive adhesive layer (Y) has photocurability that is cured by irradiation with light having a wavelength of 405 nm, even if it contains an ultraviolet absorber, the photocuring is not inhibited. For this reason, it can also combine the outstanding ultraviolet-ray cut property by harming the property with which this adhesive sheet is equipped by containing a ultraviolet absorber.

As said ultraviolet absorber, a benzotriazole type ultraviolet absorber, a benzophenone type ultraviolet absorber, a triazine type ultraviolet absorber etc. can be mentioned, for example. In addition, the said ultraviolet absorber may be used individually or in combination of 2 or more types.
Among these, the ultraviolet absorber is particularly preferably a triazine-based ultraviolet absorber from the viewpoints of transparency, ultraviolet absorption and compatibility.

[Preferred Composition Aspect of the Resin Composition]
As an example of a preferable present resin composition for forming the adhesive layer (Y), a (meth) acrylic acid ester (co) polymer (a), the crosslinking agent (b), a visible light initiator (c), The composition containing a silane coupling agent can be mentioned as needed.
Among these, as the visible light initiator (c), it is preferable to use a visible light initiator (c) having an extinction coefficient at a wavelength of 405 nm of 10 mL / (g · / cm) or more, and the visible light initiator (c) ), It is particularly preferable to use the cleavage type visible light initiator (c-1) and / or the hydrogen abstraction type visible light initiator (c-2).

Among them, (meth) acrylic acid ester (co) polymer (a) has a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, a hydroxyl group and an isocyanate group, an amino group and an isocyanate group, and a carboxyl group and an isocyanate group. It is preferable that a chemical bond is formed by a combination of any functional group selected from among them.
The (meth) acrylic acid ester (co) polymer (a) is a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain and the hydrophilic (meth) acrylate described above. Is preferable as a copolymer component.
Furthermore, it is preferable that a crosslinking agent (b) is the said polyfunctional (meth) acrylate (b-1).

As an example of a preferable present resin composition for forming the adhesive layer (Y), the (meth) acrylic acid ester copolymer (a-1) comprising a graft copolymer having a macromonomer as a branch component, and the crosslinking The composition containing an agent (b), a visible light initiator (c), and a silane coupling agent as needed can be mentioned.
Among these, as the visible light initiator (c), it is preferable to use a visible light initiator (c) having an extinction coefficient at a wavelength of 405 nm of 10 mL / (g · / cm) or more, and the visible light initiator (c) ), It is particularly preferable to use the cleavage type visible light initiator (c-1) and / or the hydrogen abstraction type visible light initiator (c-2).

Among these, the (meth) acrylic acid ester (co) polymer (a-1) is a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain described above as a skeleton component (main component). And a hydrophilic (meth) acrylate as a copolymer component.
Moreover, it is preferable that a crosslinking agent (b) is the said polyfunctional (meth) acrylate (b-1).

As still another example of the preferred resin composition for forming the adhesive layer (Y), the above (meth) acrylic comprising a graft copolymer having a macromonomer as a branch component and having an active energy ray crosslinkable structure site. The composition containing an acid ester copolymer (a-1), the said crosslinking agent (b), the said visible light initiator (c), and a silane coupling agent as needed can be mentioned.
Among these, as the visible light initiator (c), it is preferable to use a visible light initiator (c) having an extinction coefficient at a wavelength of 405 nm of 10 mL / (g · / cm) or more, and the visible light initiator (c) ), It is particularly preferable to use the cleavage type visible light initiator (c-1) and / or the hydrogen abstraction type visible light initiator (c-2).

Among these, the (meth) acrylic acid ester (co) polymer (a-1) is a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain described above as a skeleton component (main component). And a hydrophilic (meth) acrylate as a copolymer component.
Moreover, it is preferable that a crosslinking agent (b) is the said polyfunctional (meth) acrylate (b-1).

If the adhesive layer (Y) is formed using the present resin composition having the above composition, an adhesive layer (Y) having a (meth) acrylic acid ester copolymer (a) or (a-1) as a base resin. ) Can exhibit self-adhesiveness while maintaining a sheet shape at room temperature, and can be filled with a pressure-sensitive adhesive to every corner of the step of the adherend surface of the bonding member. In addition, the visible light initiator (c) can be photocured by irradiation with visible light, and the cohesive force can be increased by photocuring to increase the foaming reliability.
Furthermore, by blending a silane coupling agent, it is possible to further improve the adhesiveness, particularly the adhesiveness to the glass material.
Moreover, since the adhesive layer (Y) having the (meth) acrylic acid ester copolymer (a-1) as a base resin has a hot melt property that melts or flows when heated in addition to the above, higher step absorbability Can have.

  As still another example of the preferable resin composition for forming the adhesive layer (Y), (meth) acrylic acid having an active energy ray-crosslinkable structure portion and having a linear alkyl group having 10 to 24 carbon atoms (Meth) acrylic acid ester (co) polymer (a-2) as a monomer component containing an ester monomer, the crosslinking agent (b), the visible light initiator (c), and, if necessary, a silane cup The composition containing a ring agent can be mentioned. Among these, as the visible light initiator (c), it is preferable to use a visible light initiator (c) having an extinction coefficient at a wavelength of 405 nm of 10 mL / (g · / cm) or more, and the visible light initiator (c) ), It is particularly preferable to use the cleavage type visible light initiator (c-1) and / or the hydrogen abstraction type visible light initiator (c-2).

If this resin composition of the above composition is used, the temporarily hardened or uncured adhesive layer (Y) can be formed in a state where there is room for photocuring, and then once or It can be photocured by two or more visible light irradiations. Thus, for example, after the pressure-sensitive adhesive sheet is bonded to an adherend, the pressure-sensitive adhesive sheet can be photocured by irradiation with visible light (“main-curing”). Can be increased.
Especially for (meth) acrylic acid ester (co) polymers that have high fluidity at room temperature and are difficult to store, visible light curing after pasting even after going through a process to improve storage by temporary curing. Curing can be advanced by subsequent processes.
Furthermore, by blending a silane coupling agent, it is possible to further improve the adhesiveness, particularly the adhesiveness to the glass material.

(Laminated structure)
As described above, when the pressure-sensitive adhesive layer (Y) has a laminated structure, the pressure-sensitive adhesive layer (Y) using the resin composition is preferably the outermost front and back layers from the viewpoint of foam resistance.
At this time, the thickness of the pressure-sensitive adhesive layer (Y) as the front and back layers is preferably 15 μm or more, and more preferably 20 μm or more. When the thickness of the pressure-sensitive adhesive layer (Y) is 15 μm or more, it is preferable in the reliability test in that there is less possibility of causing problems such as foaming by being defeated by the outgas pressure generated from the adherend member.

Moreover, from the viewpoint of combining storage stability, it may be preferable to further include another layer having a higher viscosity than the pressure-sensitive adhesive layer (Y).
That is, the pressure-sensitive adhesive layer (Y) formed using the graft copolymer provided with the macromonomer is in an uncrosslinked state before photocuring, and when a polyfunctional (meth) acrylate monomer is used, Due to the action of the (meth) acrylate monomer component, the pressure-sensitive adhesive layer (Y) before photocuring may be a relatively low viscosity layer.
Therefore, in such a case, it is preferable that another layer (Z) having a higher viscosity than the pressure-sensitive adhesive layer (Y) is laminated on the pressure-sensitive adhesive layer (Y).
For example, if it is a multilayer structure consisting of three layers of adhesive layer (Y) / layer (Z) / adhesive layer (Y), it can have excellent storage stability.
From the viewpoint of such storage stability, the viscosity of the other layer (Z) is preferably 1 to 10 kPa · s, and 1.5 to 5 kPa · s in a temperature range of 70 ° C. to 100 ° C. More preferably.
In addition, this viscosity is a value measured according to the method as described in an Example.

Further, when the pressure-sensitive adhesive sheet has a multilayer structure as described above, the glass transition temperature (Tg) after irradiation of 405 nm light of the pressure-sensitive adhesive sheet is less than 20 ° C. from the viewpoint of further combining shock absorption. Preferably, it is less than 10 ° C.
When this pressure-sensitive adhesive sheet has such a relatively low Tg, low-temperature pressure-sensitive adhesive properties (such as low-temperature peel strength) can be improved, and shock absorption can be achieved.
Therefore, from the viewpoint of impact resistance absorption, the Tg of the other layer laminated with the adhesive layer (Y) after irradiation with 405 nm light is less than 15 ° C., particularly less than 10 ° C., particularly less than 5 ° C. Particularly preferred.
The Tg is a value measured at the peak temperature of Tan δ of dynamic viscoelasticity, and in detail is a value measured according to the method described in the examples.

<Adhesive sheet with release film>
This pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet with a release film.
For example, a single-layer or multilayer sheet-like adhesive layer may be formed on the release film to form an adhesive sheet with a release film.

As a material for the release film, a known release film can be used as appropriate.
As the material of the release film, for example, a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a triacetyl cellulose film, a film obtained by applying a silicone resin to a release process, Release paper or the like can be appropriately selected and used.

When a release film is laminated on both sides of the pressure-sensitive adhesive sheet, one release film may have the same laminate structure or material as the other release film, or may have a different laminate structure or material. Good.
Further, the thickness may be the same or different.
Moreover, the release film from which peeling force differs, and the release film from which thickness differs can be laminated | stacked on both sides of this adhesive sheet.

The release film preferably has a light transmittance of 40% or less at a wavelength of 410 nm or less.
By laminating a release film having a light transmittance of 40% or less at a wavelength of 410 nm or less on at least one surface of this pressure-sensitive adhesive sheet, it is possible to effectively prevent photopolymerization from proceeding by irradiation with visible light. Can do.
From this viewpoint, the release film laminated on one or both surfaces of the pressure-sensitive adhesive sheet preferably has a light transmittance of 40% or less at a wavelength of 410 nm or less, particularly 30% or less, and more preferably 20% or less. More preferably.

Here, as a release film having a light transmittance of 40% or less at a wavelength of 410 nm or less, that is, a film having a function of partially blocking transmission of visible light and ultraviolet light, for example, polyester-based, polypropylene-based, A laminated film with an ultraviolet absorbing layer formed by applying a re-peelable fine-adhesive resin on one side of a polyethylene cast film or stretched film and applying a paint containing an ultraviolet absorber on the other side. Can be mentioned.
Moreover, the thing which apply | coated the slightly adhesive resin with the removability which mix | blended the ultraviolet absorber to one side of a polypropylene-type and a polyethylene-type cast film and a stretched film can be mentioned.
Moreover, the thing which apply | coated the slightly adhesive resin which has a removability to the cast film and stretched film which consist of polyester type, a polypropylene type, and polyethylene-type resin which mix | blended the ultraviolet absorber can be mentioned.
In addition, a multilayer cast film or stretched film formed by molding a layer made of a resin not containing an ultraviolet absorber on one or both sides of a layer made of a polyester, polypropylene, or polyethylene resin containing an ultraviolet absorber. One surface may be one in which a slightly adhesive resin having removability is applied.
In addition, a UV-absorbing layer is applied to one side of a cast film or stretched film made of polyester, polypropylene, or polyethylene resin, and an ultraviolet absorbing layer is provided. The thing which apply | coated the slightly adhesive resin which has property can be mentioned.
In addition, a cast film or stretched film made of polyester, polypropylene, or polyethylene resin is coated on one side with a paint containing an ultraviolet absorber to provide an ultraviolet absorption layer, and the other side has a removability. The thing which apply | coated the adhesive resin can be mentioned.
Furthermore, the other side of the resin film made of a polyester-based, polypropylene-based, or polyethylene-based resin coated with a slightly peelable resin having removability on one surface, and a separately prepared resin film, include an ultraviolet absorber. Examples thereof include those laminated via an adhesive layer or an adhesive layer.
The film may have other layers as necessary, such as an antistatic layer, a hard coat layer, and an anchor layer.

  The thickness of the release film is not particularly limited. Among them, for example, from the viewpoint of workability and handling properties, it is preferably 25 μm to 500 μm, more preferably 38 μm or more and 250 μm or less, and particularly preferably 50 μm or more or 200 μm or less.

The pressure-sensitive adhesive sheet employs, for example, a method of directly extruding the resin composition or a method of molding by pouring into a mold without using an adherend or a release film as described above. You can also
Furthermore, it can also be set as the aspect of this adhesive sheet by directly filling this resin composition between the structural members for image display apparatuses which are adherends.

<Manufacturing method of this adhesive sheet>
An example of the method for producing the pressure-sensitive adhesive sheet will be described.
First, (meth) acrylic acid ester (co) polymer (a) and visible light initiator (c), if necessary, further crosslinking agent (b), if necessary further silane coupling agent (d), necessary Depending on the case, the present resin composition may be prepared by mixing predetermined amounts of other materials.
These mixing methods are not particularly limited, and the order of mixing the components is not particularly limited. In addition, a heat treatment step may be included at the time of producing the composition. In this case, it is desirable to perform the heat treatment after mixing each component of the resin composition in advance.
Moreover, you may use what concentrated various mixing components and mastered.

The apparatus for mixing is not particularly limited, and for example, a universal kneader, a planetary mixer, a Banbury mixer, a kneader, a gate mixer, a pressure kneader, three rolls, and two rolls can be used. You may mix using a solvent as needed.
Moreover, this resin composition can be used as a solvent-free system which does not contain a solvent. By using it as a solvent-free system, the solvent does not remain, and there can be provided the advantages that heat resistance and light resistance are improved.
Also from this viewpoint, it is preferable that this resin composition is a form containing (meth) acrylic acid ester (co) polymer (a), a crosslinking agent (b), and a visible light initiator (c).

This pressure-sensitive adhesive sheet can be produced by applying (coating) the resin composition prepared as described above onto a base sheet or a release sheet.
Further, for example, the present pressure-sensitive adhesive sheet having a laminated structure is formed by applying (coating) the resin composition on a base sheet or a release sheet to form a first layer, and forming the first layer. A method of repeating the formation of the second layer by applying (coating) the resin composition on the layer, or forming the first and second layers in the same manner as described above. Then, each of the coated (coating) surfaces is bonded to each other, and the resin composition is produced by a method of simultaneously forming the first layer and the second layer by multilayer coating or coextrusion molding. can do.

  The application (coating) method is not particularly limited as long as it is a general coating method. For example, methods such as roll coating, die coating, gravure coating, comma coating, and screen printing can be exemplified.

  And, if necessary, the adhesive layer made of the present resin composition is irradiated with light, the adhesive layer (Y) is temporarily cured, leaving room for photocuring, and the gel of the adhesive layer (Y) The fraction may be 0 to 60%. However, the adhesive layer (Y) may not necessarily be temporarily cured by irradiating light, for example, the adhesive layer (Y) may be temporarily cured by heat or curing, and may remain uncured. Also good.

<Use of this adhesive sheet>
As described above, the pressure-sensitive adhesive sheet can be suitably used for bonding the resin member (X).
For example, the resin member (X) and the image display panel (P) are bonded together via this pressure-sensitive adhesive sheet to form a photocurable pressure-sensitive adhesive sheet laminate, and the integrated light quantity at 405 nm from the resin member (X) side. The adhesive layer (Y) is photocured by irradiating the pressure-sensitive adhesive sheet through the resin member (X) with light having a value of 3000 (mJ / cm ² ), and the difference in gel fraction before and after photocuring is 10% or more. As a result, the image display panel laminate can be produced.

(Resin member (X))
The resin member (X) preferably has a light transmittance at 365 nm of 10% or less and a light transmittance at 405 nm of 60% or more.

If the light transmittance at 365 nm is 10% or less and the light transmittance at 405 nm is 60% or more, the transmission of ultraviolet rays is sufficiently blocked (cut), and the resin member (X) itself and its back side (visible) Suppressing optical deterioration of an optical member (for example, an optical film such as a polarizing film or a retardation film) located on the side opposite to the side surface, and reducing yellowness (YI) to a level required for the optical member Can do.
As such a resin member (X), a resin material is used as a main component, and a resin material adjusted to have the light transmittance using an ultraviolet absorber can be exemplified.

Examples of the resin material include a material containing a polycarbonate resin or an acrylic resin as a main component resin.
In this case, the “main component resin” means a resin having the largest content in the resin constituting the resin member (X).

(Image display panel (P))
The image display panel (P) is composed of, for example, another optical film such as a polarizing film or other retardation film, a liquid crystal material, and a backlight system. There are STN method, VA method, IPS method, etc. depending on the control method of the liquid crystal material, but any method may be used.
Further, the image display panel may be an in-cell type in which a touch panel function is incorporated in a TFT-LCD, or an on-cell type in which a touch panel function is incorporated between a polarizing plate and a glass substrate provided with a color filter.

The pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer (Y) in a state in which the object is adhered as described above, that is, the pressure-sensitive adhesive layer (Y) after light (main) curing, from the viewpoint of foaming reliability. It is particularly preferable to have a cross-linked structure.
In particular, as described above, the pressure-sensitive adhesive layer (Y) uses a (meth) acrylic acid ester copolymer having an active energy ray-curable site, or a (meth) acrylic acid ester having a functional group (i) ( Co-polymer (a) and a compound having a functional group (ii) that reacts with the functional group (i) to form a chemical bond, or an alkylene oxide unmodified trifunctional or higher polyfunctional (meth) It is particularly preferable to form using acrylate and to have a crosslinked structure resulting from these.

<< Explanation of words and phrases >>
In the present invention, even when referred to as “film”, “sheet” is included, and even when referred to as “sheet”, “film” is included.
In addition, the expression “panel” such as an image display panel and a protection panel includes a plate, a sheet and a film.

In the present invention, when described as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” or “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It also includes the meaning of “smaller”.
Further, when it is described as “X or more” (X is an arbitrary number), it means “preferably greater than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). In the case, unless otherwise specified, the meaning of “preferably smaller than Y” is also included.

  Examples will be described in more detail below. However, the present invention is not limited to the examples described below.

<Examples and comparative examples>
The materials used in Examples and Comparative Examples will be described.

[Example 1]
(Photocurable adhesive sheet Y)
As a (meth) acrylic acid ester (co) polymer, 13.5 parts by mass of a macromonomer (number average molecular weight 3000) having a terminal functional group of methacryloyl group consisting of isobornyl methacrylate: methyl methacrylate = 1: 1, An acrylic graft copolymer (mass average molecular weight: 160,000) prepared by random copolymerization of 43.7 parts by mass of lauryl acrylate, 40 parts by mass of 2-ethylhexyl acrylate, and 2.8 parts by mass of acrylamide was prepared.
A mixture containing 90 g of propoxylated pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATM-4PL) as a crosslinking agent, and a cleavage-type visible light initiator as a visible light initiator with respect to 1 kg of this acrylic graft copolymer. 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), 2,4,6-trimethyl 15 g of a mixture of benzophenone and 4-methylbenzophenone (Esacure KTO46 manufactured by Lamberti) was added and mixed uniformly to obtain a photocurable composition.
Next, after forming the photocurable composition into a sheet shape having a thickness of 150 μm on a polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm) whose surface has been subjected to a release treatment, A polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRQ, thickness 75 μm) whose surface was peeled was coated to prepare a photocurable pressure-sensitive adhesive sheet Y1 with a release film.
The photocurable pressure-sensitive adhesive sheet Y1 was a pressure-sensitive adhesive sheet having photocurability that is cured by irradiating light.

(Resin member X)
The resin member (X) is a polycarbonate-based resin plate (Mitsubishi Gas Chemical Co., Ltd., Iupilon sheet MR58) containing an ultraviolet absorber, and has a thickness of 1.0 mm (used in the bonding configuration P) and 1.5 mm (sticking). Used in combination structure Q and bonding structure R).
In any thickness, the light transmittance at 365 nm was 0%, and the light transmittance at 405 nm was 83%.

(Photo curable adhesive sheet laminate)
The release film on one surface of the photocurable pressure-sensitive adhesive sheet Y1 with a release film is peeled off and roll-bonded to one surface of the polycarbonate plate (resin member X), and the resin member (X) / photocurable pressure-sensitive adhesive sheet Y1. The photocurable pressure-sensitive adhesive sheet laminate (also referred to as “X / Y1 laminate”) was obtained.

[Example 2]
Except for changing the type of the crosslinking agent of the photocurable pressure-sensitive adhesive sheet Y to pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATMM3), and changing the number of blended parts to 70 g with respect to 1 kg of the acrylic graft copolymer, In the same manner as in Example 1, photocurable pressure-sensitive adhesive sheets Y2 and X / Y2 laminates were obtained.
The photocurable pressure-sensitive adhesive sheet Y2 was a pressure-sensitive adhesive sheet having photocurability that is cured by irradiating light.

[Example 3]
The composition of the (meth) acrylic copolymer of the photocurable pressure-sensitive adhesive sheet Y is composed of a macromonomer (number average molecular weight 3000) consisting of isobornyl methacrylate: methyl methacrylate = 1: 1 and having a terminal functional group of methacryloyl group. 12.7 parts by weight, 41.1 parts by weight of lauryl acrylate, 37.6 parts by weight of 2-ethylhexyl acrylate, 2.6 parts by weight of acrylamide and 6 parts by weight of 4-hydroxybutyl acrylate Active energy of carbon-carbon double bond obtained by addition reaction of 6.5 parts by mass of 2-isocyanatoethyl methacrylate to 100 parts by mass of the acrylic graft copolymer (mass average molecular weight: 160,000) Same as Example 1 except that the copolymer is changed to a (meth) acrylic copolymer having a linear crosslinkable structure site. To obtain a photo-curable adhesive sheet Y3 and X / Y3 laminate. The photocurable pressure-sensitive adhesive sheet Y3 was a pressure-sensitive adhesive sheet having photocurability that is cured by irradiating light.

[Example 4]
As the photocurable pressure-sensitive adhesive sheet, phenyl glyoxylic acid methyl ester (Irgacure MBF, manufactured by BASF), which is a hydrogen abstraction type visible light initiator, is used as the visible light initiator, and the accumulated light amount at 405 nm is 100 ( mJ / cm ² ) A photocurable pressure-sensitive adhesive sheet Y4 and an X / Y4 laminate are obtained in the same manner as in Example 1 except that a material that is first cured (crosslinked) by irradiation with light so as to be mJ / cm ² is used. It was.
The photocurable pressure sensitive adhesive sheet Y4 was a pressure sensitive adhesive sheet that was cured by irradiating light.

[Example 5]
As a (meth) acrylic acid ester (co) polymer, 13.5 parts by mass of a macromonomer (number average molecular weight 3000) having a terminal functional group of methacryloyl group consisting of isobornyl methacrylate: methyl methacrylate = 1: 1, An acrylic graft copolymer (mass average molecular weight: 260,000) obtained by random copolymerization of 73.7 parts by mass of 2-ethylhexyl acrylate, 2.8 parts by mass of acrylamide and 10 parts by mass of methyl acrylate is used as a crosslinking agent. In the same manner as in Example 1, except that pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATMM3L) was changed to 70 g with respect to 1 kg of the acrylic graft copolymer. Curable adhesive sheets Y5 and X / Y5 laminate were obtained.
The photocurable pressure-sensitive adhesive sheet Y5 was a pressure-sensitive adhesive sheet having photocurability that is cured by irradiation with light.

[Example 6]
A photocurable pressure-sensitive adhesive sheet Y6 and an X / Y6 laminate were obtained in the same manner as in Example 5, except that the amount of the crosslinking agent was changed to 120 g with respect to 1 kg of the acrylic graft copolymer.
The photocurable pressure-sensitive adhesive sheet Y6 was a pressure-sensitive adhesive sheet having photocurability that is cured by irradiation with light.

[Example 7]
As for the type of the crosslinking agent, pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATMM3L) and dipentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A9570W) are used for 1 kg of the acrylic graft copolymer. A photocurable pressure-sensitive adhesive sheet Y7 and an X / Y7 laminate were obtained in the same manner as in Example 5 except that 90g and 30g were used in combination.
The photocurable pressure-sensitive adhesive sheet Y7 was a pressure-sensitive adhesive sheet having photocurability that was cured by irradiating light.

[Example 8]
The type of crosslinking agent is 120 g of pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATMM3L) and dipentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A9570W) per 1 kg of the acrylic graft copolymer. The photocurable pressure-sensitive adhesive sheet Y8 and the X / Y8 laminate were obtained in the same manner as in Example 5 except that 40 g was used in combination.
In addition, photocurable adhesive sheet Y8 was an adhesive sheet provided with photocurability which hardens | cures by irradiating light.

[Example 9]
As a (meth) acrylic copolymer, 13.5 parts by mass of a macromonomer (number average molecular weight of 3,000) having a terminal functional group of methacryloyl group consisting of isobornyl methacrylate: methyl methacrylate = 1: 1, 2 -As a crosslinking agent for 1 kg of an acrylic graft copolymer (mass average molecular weight: 260,000) obtained by random copolymerization of 73.7 parts by mass of ethylhexyl acrylate, 2.8 parts by mass of acrylamide and 10 parts by mass of methyl acrylate Pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester ATMM3L) and dipentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A9570W) are used together in amounts of 75 g and 25 g, respectively, and cleaved as a visible light initiator. 2, 4, 6 which are mixtures containing type visible light initiators Mixture of trimethylbenzoyl-diphenyl-phosphine oxide, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), 2,4,6-trimethylbenzophenone, 4-methylbenzophenone 15 g (Esacure KTO46 manufactured by Lamberti) was added, and 2 g of 3-glycidoxypropyltrimethoxysilane (KBM403 manufactured by Shin-Etsu Silicon Co., Ltd.) as a silane coupling agent was uniformly mixed to obtain a photocurable composition.
Next, after the photocurable composition was molded into a sheet shape having a thickness of 25 μm on a polyethylene terephthalate film (Mitsubishi Chemical Co., Ltd., Diafoil MRV, thickness 100 μm) whose surface was peeled. Then, a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil MRQ, thickness 75 μm) whose surface was peeled was coated to prepare an adhesive sheet Y9a for front and back layers with a release film.

As a (meth) acrylic copolymer, 1 kg of the same acrylic graft copolymer used in the front and back layer pressure-sensitive adhesive sheet Y9a, pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK Ester ATMM3L) as a crosslinking agent ) 30 g, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, oligo (2-hydroxy-2-methyl-1- (4- 15 g of (1-methylvinyl) phenyl) propanone), 2,4,6-trimethylbenzophenone, 4-methylbenzophenone (Esacure KTO46 manufactured by Lamberti) was added and mixed uniformly to obtain a photocurable composition. It was.
Next, after the photocurable composition is formed into a sheet shape having a thickness of 100 μm on a polyethylene terephthalate film (Mitsubishi Chemical Co., Ltd., Diafoil MRV, thickness: 100 μm) whose surface is peeled. Then, a polyethylene terephthalate film (Mitsubishi Chemical Co., Ltd., Diafoil MRQ, thickness 75 μm) whose surface was peeled was coated to prepare an intermediate layer pressure-sensitive adhesive sheet Y9b with a release film.

  The PET films on both sides of the intermediate layer pressure-sensitive adhesive sheet Y9b are sequentially peeled and removed, and the adhesive surfaces of the two front and back layer pressure-sensitive adhesive sheets Y9a are sequentially bonded to both surfaces of the intermediate layer pressure-sensitive adhesive sheet Y9b. Photocurable pressure-sensitive adhesive sheet Y9 and Example 1, which is a laminate of two types and three layers (total thickness 150 μm) consisting of pressure-sensitive adhesive sheet Y9a) / (pressure-sensitive adhesive sheet Y9b for intermediate layer) / (pressure-sensitive adhesive sheet Y9a for front and back layers) Similarly, an X / Y9 laminate was obtained.

[Example 10]
The (meth) acrylic copolymer used for the intermediate layer pressure-sensitive adhesive sheet Y9b is composed of a macromonomer (number average molecular weight 3, 3) consisting of isobornyl methacrylate: methyl methacrylate = 1 and having a terminal functional group of methacryloyl group. 000) is an acrylic graft copolymer (mass average) obtained by random copolymerization of 13.5 parts by mass, 43.7 parts by mass of lauryl acrylate, 40 parts by mass of 2-ethylhexyl acrylate, and 2.8 parts by mass of acrylamide. (Adhesive sheet for front and back layers Y9a) / (Adhesive sheet for intermediate layers Y10b) / (For front and back layers) In the same manner as in Example 9 except that the pressure-sensitive adhesive sheet Y10b for intermediate layers was formed by changing the molecular weight to 160,000. Photocurable pressure-sensitive adhesive sheets Y10 and X / Y10 laminates, which are two-layered and three-layered laminates (total thickness 150 μm) composed of adhesive sheets Y9a), are obtained. .
The photocurable pressure-sensitive adhesive sheet Y10 was a pressure-sensitive adhesive sheet that was cured by irradiating light.

[Comparative Example 1]
Except for using a mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone (Lamberti, Esacure TZT), which is a hydrogen abstraction initiator as a photoinitiator, as a photocurable pressure-sensitive adhesive sheet In the same manner as in No. 1, a photocurable pressure-sensitive adhesive sheet Y11 and an X / Y11 laminate were obtained.

[Comparative Example 2]
As a photocurable pressure-sensitive adhesive sheet, 1- [4- (4-benzoylphenylsulfanyl) phenyl] -2-methyl-2- (4-methylphenylsulfonyl) propane- which is a hydrogen abstraction type initiator as a photoinitiator A photocurable pressure-sensitive adhesive sheet Y12 and an X / Y12 laminate were obtained in the same manner as in Example 1 except that 1-one (Lamberti, Esacure 1001M) was used.

[Comparative Example 3]
As the photocurable pressure-sensitive adhesive sheet, Example 1 except that 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., DETX-S), which is a visible light absorbing hydrogen abstraction type initiator, was used as a photoinitiator. Similarly, the photocurable adhesive sheet Y13 and the X / Y13 laminated body were obtained.

[Comparative Example 4]
The photocurable pressure-sensitive adhesive sheet Y14 and the X / Y14 laminate are the same as in Example 1 except that a commercially available non-curable transparent adhesive sheet for non-optical optics is used as the photocurable pressure-sensitive adhesive sheet. Got.

<Evaluation>
An evaluation method displayed in this specification will be described.

(1) Dynamic storage elastic modulus (G ′)
For each of 150 μm photocurable pressure-sensitive adhesive sheets Y1 to Y14 (no release film) obtained in the examples and comparative examples, 8 sheets were stacked to 1200 μm, and a dynamic viscoelasticity measuring device rheometer (Eiko Seiki Co., Ltd.) Using “MARS”), measurement was performed under the conditions of adhesive jig: Φ25 mm parallel plate, strain: 0.5%, frequency 1 Hz, temperature increase rate: 3 ° C./min.

(2) Spectral transmittance About resin member (X), the spectral transmittance (% T) of wavelength 300nm -800nm was measured using the spectrophotometer (Shimadzu Corporation UV2000). Such spectral transmittance was defined as light transmittance.

(3) Gel fraction Each of the photocurable pressure-sensitive adhesive sheets Y1 to Y14 (no release film) obtained in the examples and comparative examples was bag-shaped with a SUS mesh (# 200) whose mass (X) was measured in advance. The bag was folded and closed, and the mass (Y) of the bag was measured. The sample was immersed in 100 ml of ethyl acetate and stored in the dark at 23 ° C. for 24 hours. The ethyl acetate attached by heating for 5 hours was evaporated, the mass (Z) of the dried packet was measured, and the obtained mass was substituted into the following formula to obtain the gel fraction X1.
Gel fraction (%) = [(Z−X) / (Y−X)] × 100

Also, for each of the obtained X / Y1~Y14 laminates in Examples and Comparative Examples, the resin member (X) side, using a high-pressure mercury lamp, the integrated amount of light at 405nm is 3000 (mJ / ^cm 2) Then, a sample was taken from the adhesive layer portion on the resin member (X) side surface of the photocurable adhesive sheet, and the gel fraction X2 was determined by the same method as described above. And X2-X1 was calculated.

(4) Step absorbency 58 mm × 110 mm × 0.8 mm thick peripheral edge of glass (long side 3 mm, short side 15 mm) is printed with a thickness of 22-24 μm, and the central recess is 52 mm × 80 mm. A glass plate with a printed step was prepared.
For each of the photocurable pressure-sensitive adhesive sheets Y1 to Y14 with a release film obtained in Examples and Comparative Examples, one release film is peeled off and the whole surface of soda lime glass (54 mm × 82 mm × thickness 0.5 mm). After the roll bonding, the other release film remaining is peeled off, and the pressure-sensitive adhesive sheet is placed on the frame-like printing step of the glass plate with printing steps using a vacuum press (temperature 25 ° C., press An evaluation sample was prepared with a pressure of 0.13 MPa.
After the evaluation sample was autoclaved under the conditions of 60 ° C., 0.2 MPa, and 20 min, the acceptability was determined according to the following evaluation criteria.
○ (good): No microbubbles are seen around the step × (poor): Microbubbles are seen around the step

(5) Yellowness (YI)
For each of the X / Y1 to Y14 laminates obtained in the examples and comparative examples, the integrated light quantity at 405 nm is 3000 (mJ / cm ² ) using a high-pressure mercury lamp from the resin member (X) side. Irradiated with light.
The accumulated light quantity at 405 nm is that of the resin member (X) using an ultraviolet accumulated light meter “UIT-250” (manufactured by USHIO INC.) And a light receiver “UVD-C405” (manufactured by USHIO ELECTRIC CO., LTD.). Measured by installing a light meter on the surface opposite to the surface irradiated with the high-pressure mercury lamp, and with the integrated light amount transmitted through the resin member (X) and irradiated onto the photocurable pressure-sensitive adhesive sheets (Y1 to Y14). is there.
Thereafter, the yellowness (YI) of the X / Y1-Y14 laminate was measured based on JIS K7103 using a spectrocolorimeter (Suga Test Instruments Co., Ltd.) “SC-T”, and the following evaluation criteria were used. Judgment was made.
○ (good): YI is less than 2 × (poor): YI is 2 or more

(6) UV resistance (ΔYI)
The resulting X / Y1~Y14 laminates in Examples and Comparative Examples, the resin member (X) side, using a high-pressure mercury lamp, the light so that the integrated quantity of light at 405nm is 3000 (mJ / cm ²⁾ Irradiated.
The accumulated light quantity at 405 nm is that of the resin member (X) using an ultraviolet accumulated light meter “UIT-250” (manufactured by USHIO INC.) And a light receiver “UVD-C405” (manufactured by USHIO ELECTRIC CO., LTD.). Measured by installing a light meter on the surface opposite to the surface irradiated with the high-pressure mercury lamp, and with the integrated light amount transmitted through the resin member (X) and irradiated onto the photocurable pressure-sensitive adhesive sheets (Y1 to Y14). is there.
Then, the irradiation test of distance 20cm and 72hr was implemented using the UVB fluorescent lamp (G15T8E Sankyo Electric Co., Ltd. make, irradiance 70microW / cm < ² >).
Pass / fail was determined by the following evaluation criteria from the amount of change ΔYI in yellowness (YI) of the X / Y1-Y14 laminate before and after irradiation.
○ (good): ΔYI is less than 0.2 × (poor): ΔYI is 0.2 or more

(7) Anti-foaming reliability For each of the X / Y laminates obtained in the examples and comparative examples, the other release film remaining on the Y surface side is peeled off, and the following three types of members are applied to the exposed surface of the hand roller. The foaming reliability at the time of pasting and pasting was evaluated.
Moreover, the X / Y laminated body was cut and used for the size of each member.
Specific bonding configurations are X / Y laminate / member P (bonding configuration P), X / Y laminate / member Q (bonding configuration Q) and X / Y laminate / member R (bonding configuration). R).
Member P: Soda lime glass 54mm x 82mm x thickness 0.55mm
Member Q: Soda lime glass 100mm x 180mm x thickness 0.55mm
Member R PET film 100mm x 180mm x thickness 100μm

  Moreover, with respect to the member P (bonding configuration P), the autoclave treatment is performed under conditions of a temperature of 60 ° C. and an atmospheric pressure of 0.2 MPa for 30 minutes to perform final bonding, and the members Q and R (bonding configuration Q). And R) were subjected to an autoclave treatment at a temperature of 80 ° C. and an atmospheric pressure of 0.2 MPa for 30 minutes, and finished.

After finishing and sticking, light is irradiated from the resin member (X) side using a high-pressure mercury lamp so that the integrated light quantity at 405 nm is 3000 (mJ / cm ² ) to produce a foam resistance evaluation sample. did.
The evaluation sample was exposed to an environment at 85 ° C. and 85% RH for 24 hours, and “◯ (good)” indicates that no poor appearance such as foaming or peeling was observed. It was determined as “× (poor)”.
Moreover, what was not recognized by the bonding structure P or Q (one-sided glass member) and bonding structure R (double-sided resin member), such as foaming and peeling, was set as “◎ (very good)”, and the bonding structure P , Q and R where no poor appearance such as foaming or peeling was recognized as “good”, and any of the bonding configurations P, Q and R where foaming or peeling was recognized as “good”. The overall judgment was “× (poor)”.

(8) Haze after long-term storage (indicator of compatibility with crosslinking agent)
For each of the photocurable pressure-sensitive adhesive sheets Y obtained in the examples and comparative examples, after two months have passed since the sheets were produced, the release films of the pressure-sensitive adhesive sheet Y were peeled off to expose the exposed double-sided pressure-sensitive adhesive surfaces. Pasting so as to be sandwiched between soda lime glass (thickness 0.55 mm), using a high pressure mercury lamp, after irradiating light so that the integrated light quantity at 405 nm was 3000 (mJ / cm ² ), the haze value was measured. .
The haze value was measured in accordance with JIS K7136 using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.).
A sample having a haze value of less than 0.5 is indicated by “Good”, a value of 0.5 or more and less than 1.0 is indicated by “△ (satisfactory)”, and a value of 1.0 or more is indicated by “×”. (Poor) ".

(9) Tg after photocuring
For each of the 150 μm photocurable pressure-sensitive adhesive sheets Y1 to Y14 (without a release film) obtained in the examples and comparative examples, light was previously accumulated so that the integrated light quantity at 405 nm was 3000 (mJ / cm ² ). , And 8 pieces of photo-curable adhesive sheets Y1 to Y14 are stacked to 1200 μm, and using a dynamic viscoelasticity measuring device rheometer (“MARS” manufactured by Eihiro Seiki Co., Ltd.), an adhesive jig: Φ25 mm parallel Measurement was performed under the conditions of plate, strain: 0.5%, frequency 1 Hz, temperature rising rate: 3 ° C./min, and the temperature at which the obtained Tan δ peaked was measured as Tg.

(10) Viscosity For each of the 150 μm photocurable pressure-sensitive adhesive sheets Y1 to Y14 (without a release film) obtained in Examples and Comparative Examples, 8 sheets are stacked to 1200 μm, and a dynamic viscoelasticity measuring device rheometer ( Using “MARS” manufactured by Eihiro Seiki Co., Ltd.), adhesive jig: Φ25 mm parallel plate, strain: 0.5%, frequency 1 Hz, heating rate: 3 ° C./min. The complex viscosity of the pressure-sensitive adhesive sheet before photocuring was measured.

(11) Storage property A laminate is prepared by sandwiching photocurable pressure-sensitive adhesive sheets Y1 to 14 cut to 50 mm × 50 mm square between two 100 mm × 100 mm square PET films having a thickness of 100 μm, and 23 ° C. and 50%. Visual observation was carried out to see if the pressure-sensitive adhesive protruded from the laminate after being allowed to stand for 300 hours.
By visually observing the produced laminate, “× (poor)” indicates that the adhesive protruded as a whole, “△ (satisfactory)” indicates that the adhesive protruded only at the corner, and the adhesive did not protrude. The thing was determined to be “good”.

<Discussion>
The photocurable adhesive sheet laminate (X / Y1 to Y10 laminate) of the resin member (X) / photocurable adhesive sheet (Y1 to Y10) of Examples 1 to 10 has a wavelength from the resin member (X) side. When light is irradiated so that the integrated light quantity at 405 nm is 3000 (mJ / cm ² ), the photocurable pressure-sensitive adhesive sheets Y1 to Y10 may be sufficiently cured so that the difference in gel fraction is increased by 10% or more. In addition, since the dynamic storage elastic modulus (G ′) maintained a high-temperature cohesive force of 0.7 × 10 ⁴ Pa or more at 120 ° C. and 1 Hz, good foaming reliability was obtained. In particular, good resistance to foaming was obtained in a test assuming that the touch sensor is a glass sensor.
Among them, in Examples 3, 7, 9, and 10, the dynamic storage elastic modulus (G ′) maintained a high-temperature cohesive force of 2.0 × 10 ⁴ Pa or higher at 120 ° C. and 1 Hz. Even in a test assuming the case of a film sensor, good anti-foaming reliability was obtained.

Further, in Example 8, good anti-foaming reliability was obtained in the test assuming that the touch sensor is a film sensor, but the glass peeled off in the test assuming that the touch sensor is a glass sensor. Occurred. This is presumably because the dynamic storage elastic modulus (G ′) became too high at 120 ° C. and 1 Hz, and the tack and adhesion performance deteriorated.
In Example 2, since the content of the hydrophilic monomer constituting the (meth) acrylic acid ester (co) polymer (a) is 10 parts by mass or less, phase separation progressed during long-term storage. The haze after long-term storage was “Δ (satisfactory)”.
In any of Examples 1 to 10, the level difference absorbability is good, and it is considered that the cover member having a printing level difference can be practically used depending on the type of touch sensor.

  In Examples 4, 9, and 10, the viscosity (70 ° C.) was as high as 1.5 kPa · s or more, and therefore, no paste was seen even after long-term storage, and the storage was excellent.

In Comparative Examples 1 and 2, the light transmittance (%) at a wavelength of 390 nm of the photocurable pressure-sensitive adhesive sheets Y11 and Y12 is as high as 90% or more, and the integrated light amount at a wavelength of 405 nm is 3000 (from the resin member (X) side). mJ / cm ² ) When the light is irradiated so that the excitation and the curing (crosslinking) reaction due to light absorption of the photoinitiator are not sufficiently progressed, the adhesive layer (Y) cannot be cured sufficiently, and is resistant to foaming. Bubbles were generated during the reliability test.

  In Comparative Example 3, since the light transmittance (%) at a wavelength of 410 nm of the photocurable pressure-sensitive adhesive sheet Y13 is as low as 70% and the light absorption in the visible light region is large, the yellowness (YI) of the pressure-sensitive adhesive layer (Y) is high. It became high.

In Comparative Example 4, since the gel fraction of the photocurable pressure-sensitive adhesive sheet Y14 is 88% and the dynamic storage elastic modulus (G ′) (25 ° C.) is as high as 1.1 × 10 ⁵ Pa, the step absorbability is poor, Bubbles were generated.

Claims (17)

A light curable pressure-sensitive adhesive sheet used for bonding a resin member (X) having a light transmittance of 10% or less at a wavelength of 365 nm and a light transmittance of 60% or more at a wavelength of 405 nm,
A photocurable pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer (Y) having all the following properties (1) to (3).
(1) The gel fraction (referred to as “gel fraction before light irradiation X1”) is in the range of 0 to 60%.
(2) The light transmittance at a wavelength of 390 nm is 89% or less, and the light transmittance at a wavelength of 410 nm is 80% or more.
(3) It has photocurability that is cured by irradiation with light having a wavelength of 405 nm.   The photocurability in the above (3) is a photocuring that increases by 10% or more as a difference in gel fraction when irradiated with light having a wavelength of 405 nm from the outside of the resin member (X) through the resin member (X). The photocurable pressure-sensitive adhesive sheet according to claim 1, wherein When light having an integrated light quantity of 3000 (mJ / cm ² ) at a wavelength of 405 nm is irradiated from the outside of the resin member (X) through the resin member (X), the gel fraction before light irradiation (light irradiation) The difference (the gel fraction after light irradiation X2−the gel fraction before light irradiation X1) between the pregel fraction X1) and the gel fraction after light irradiation (referred to as “gel fraction after light irradiation X2”) is 10%. The photocurable pressure-sensitive adhesive sheet according to claim 1, comprising the photocurable property as described above.   The said adhesive layer (Y) contains a (meth) acrylic acid ester (co) polymer and a visible light initiator, The photocurable adhesive sheet in any one of Claims 1-3 characterized by the above-mentioned.   The photocurable pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer (Y) contains a silane coupling agent.   The (meth) acrylic acid ester (co) polymer is selected from among a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, a hydroxyl group and an isocyanate group, an amino group and an isocyanate group, and a carboxyl group and an isocyanate group. The photocurable pressure-sensitive adhesive sheet according to claim 4, wherein a chemical bond is formed by a combination of any of the functional groups.   The photocurable pressure-sensitive adhesive sheet according to claim 4 or 5, wherein the (meth) acrylic acid ester (co) polymer is a graft copolymer having a macromonomer as a branch component.   The photocurable pressure-sensitive adhesive sheet according to any one of claims 4 to 7, wherein the visible light initiator is a hydrogen abstraction type visible light initiator.   The hydrogen abstraction type visible light initiator includes phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2- [2-oxo-2-phenyl-acetoxy-ethoxy] ethyl ester and oxy-phenyl-acetic acid. The photocurable pressure-sensitive adhesive sheet according to claim 8, which is one or two selected from the group consisting of a mixture of 2- [2-hydroxy-ethoxy] ethyl ester.   The (meth) acrylic acid ester (co) polymer includes a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain and a hydrophilic (meth) acrylate as a copolymer component. The photocurable pressure-sensitive adhesive sheet according to any one of claims 4 to 9, which is a copolymer.   The said adhesive layer (Y) is a photocurable adhesive sheet in any one of Claims 1-10 containing a crosslinking agent or formed using a crosslinking agent.   The photocurable pressure-sensitive adhesive sheet according to claim 11, wherein the cross-linking agent is a trifunctional or higher polyfunctional (meth) acrylate not modified with alkylene oxide.   The photocurable pressure-sensitive adhesive sheet according to any one of claims 4 to 12, wherein the (meth) acrylic acid ester (co) polymer has an active energy ray crosslinkable structure site. The photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 13, which has a storage elastic modulus (G ') of 0.9 x 10 ⁵ Pa or less at a temperature of 25 ° C and a frequency of 1 Hz. The storage elastic modulus (G ′) of the pressure-sensitive adhesive layer (Y) after irradiation with light having an integrated light quantity of 3000 (mJ / cm ² ) at a wavelength of 405 nm is 0.7 × at a temperature of 120 ° C. and a frequency of 1 Hz. It becomes 10 < ⁴ > Pa or more, The photocurable adhesive sheet in any one of Claims 1-14 characterized by the above-mentioned. The storage elastic modulus (G ′) of the pressure-sensitive adhesive layer (Y) after irradiation with light having an integrated light quantity of 3000 (mJ / cm ² ) at a wavelength of 405 nm is 2.0 × at a temperature of 120 ° C. and a frequency of 1 Hz. It becomes 10 < ⁴ > Pa or more, The photocurable adhesive sheet in any one of Claims 1-14 characterized by the above-mentioned. The photocurable pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer (Y) has a hot-melt property that softens or flows when heated.