JP2020183488A - Adhesive sheet, manufacturing method of laminate, and laminate - Google Patents

Abstract

To provide a pressure-sensitive adhesive sheet which includes a pressure-sensitive adhesive layer with post-cure property and is excellent in processability when the pressure-sensitive adhesive layer is post-cured.SOLUTION: The pressure-sensitive adhesive sheet is provided which includes a pressure-sensitive adhesive layer formed by making an adhesive pressure-sensitive adhesive composition semi-cured, and in which the pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a crosslinking agent, a monomer having at least one reactive double bond in a molecule, and a polymerization initiator, and in which glass transition temperature (Tg) of a homopolymer when the monomer is polymerized is 30°C or more, the pressure-sensitive adhesive layer has a post-cure property, and the pressure-sensitive adhesive sheet satisfies the following physical properties when the pressure-sensitive adhesive layer is post-cured; shear storage modulus G' measured at 23°C and frequency of 1 Hz is 1×106 [Pa] or more, shear storage modulus G' measured at 75°C and frequency of 1 Hz is 1×105 [Pa] or more and probe tack value measured at 23°C is 1.5 N/5 mmφ or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive sheet, a method for producing a laminate, and a laminate.

Display devices such as liquid crystal displays (LCDs) and input devices used in combination with display devices such as touch panels are widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for bonding optical members, and transparent adhesive sheets are also used for bonding display devices and input devices. ..

It is known that there are several polymerization methods for the crosslinkable acrylic polymer that forms the pressure-sensitive adhesive sheet, as described below. Specifically, two steps of (1) polymerization by heat, (2) polymerization by active energy rays, (3) polymerization by heat (or active energy rays), and then polymerization by active energy rays (or heat). There are methods such as polymerization and (4) two-stage polymerization in which polymerization is carried out by active energy rays after polymerization by active energy rays.

In recent years, as a method for forming an adhesive sheet used for the above-mentioned applications, (3) polymerization by heat (or active energy ray) and then polymerization by active energy ray (or heat) is performed by two-stage polymerization. A curing method may be used. Since such an adhesive sheet is formed from an adhesive composition having both thermosetting property and active energy ray curable property (hereinafter, may be referred to as "dual curing type adhesive composition"), it is thermosetting. It has properties and active energy ray curability. Therefore, it can be temporarily adhered by performing only thermosetting, for example, before being bonded to the adherend, and then further cured by active energy rays (referred to as post-curing or after-cure). Can be firmly adhered to the body.

An example of a method of forming an adhesive sheet by the method (3) is known.
For example, Patent Document 1 describes a base polymer (A) containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and a lauryl acrylate (b1). A monomer (B) containing the above, a cross-linking agent (C) that reacts with the base polymer (A) by heat, and a polymerization initiator (D) that initiates the polymerization reaction of the monomer (B) by irradiation with active energy rays. ) And the solvent (E), and a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer obtained by semi-curing the pressure-sensitive adhesive composition by heating is described.
In Patent Document 2, glass plates are bonded to each other, glass plates and synthetic resin plates or synthetic resin plates are bonded to each other, and a pressure-sensitive adhesive sheet having at least one UV-curable pressure-sensitive adhesive layer is used. A method for producing a transparent laminate in which the pressure-sensitive adhesive layer is cured by ultraviolet rays by irradiating with ultraviolet rays from the side is described.

Japanese Unexamined Patent Publication No. 2016-084391 Japanese Unexamined Patent Publication No. 2012-031059

When the present inventors examined the characteristics of the pressure-sensitive adhesive sheet described in Patent Documents 1 and 2, the processability of the pressure-sensitive adhesive sheet after post-curing was determined by the usual method (1) or (2) above. It was found that the performance was about the same as that of the seat.

An object to be solved by the present invention is to provide a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer has post-curability and is excellent in processability when the pressure-sensitive adhesive layer is post-cured.

As a result of diligent studies to solve the above problems, the present inventors have determined the shear storage elastic modulus G'when the pressure-sensitive adhesive layer is post-cured by using the pressure-sensitive adhesive layer having post-curing property. We have found that by setting the probe tack value to a specific range or more and the probe tack value when the pressure-sensitive adhesive layer is post-cured to a specific range or less, it is possible to provide an adhesive sheet having excellent workability when the pressure-sensitive adhesive layer is post-cured. It was.

The present invention and preferred configurations of the present invention are as follows.
[1] Having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state,
The pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a crosslinker, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator.
The glass transition temperature (Tg) of the homopolymer when the monomer is polymerized is 30 ° C. or higher, and the pressure-sensitive adhesive layer has post-curability.
An adhesive sheet that satisfies the following physical property group (1) when the adhesive layer is post-cured.
Physical property group (1): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 1 × 10 ⁶ [Pa] or more, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or more, and the probe tack value measured at 23 ° C. and the following measurement conditions is 1.5 N / 5 mmφ or less.
(Measurement conditions for probe tack value)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5 mmφ
Probe base material: Stainless steel surface finish AA # 400 Mirror surface weight by polishing: 19.6 ± 0.2 g (made of brass)
Probe moving speed: 1.0 cm / sec Duel time: 1 sec.
[2] The pressure-sensitive adhesive sheet according to [1], wherein the pressure-sensitive adhesive layer satisfies the following physical property group (2) in a semi-cured state.
Physical property group (2): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 8 × 10 ⁵ [Pa] or less, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or less, and the probe tack value measured at 23 ° C. and the above measurement conditions is 2.0 N / 5 mmφ or more.
[3] The pressure-sensitive adhesive sheet according to [1] or [2], wherein when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 70 to 100% by mass.
[4] The gel fraction of the pressure-sensitive adhesive layer in the semi-cured state is 0% by mass or more and less than 70% by mass, and
The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 5% by mass or more higher than the gel fraction in the semi-cured state.
[5] The crosslinkable functional group of the crosslinkable acrylic polymer is one or more selected from a carboxy group, a hydroxy group, an amino group, an amide group, a glycidyl group and an isocyanate group [1] to [1] to [ 4] The adhesive sheet according to any one of.
[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5], wherein the cross-linking agent is one or more selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound.
[7] The pressure-sensitive adhesive sheet according to any one of [1] to [6], wherein the pressure-sensitive adhesive composition contains 5 to 40 parts by mass of a monomer with respect to 100 parts by mass of the crosslinkable acrylic polymer.
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the polymerization initiator has an ability to initiate polymerization by irradiation with active energy rays.
[9] Described in any one of [1] to [8], which comprises a pair of release sheets having different peeling forces on both sides of the pressure-sensitive adhesive layer, or a transparent base material / pressure-sensitive adhesive layer / release sheet. Adhesive sheet.
[10] After the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to [9] is attached to the adherend in a semi-cured state, the pressure-sensitive adhesive layer is rearranged by irradiating with active energy rays. A method for producing a laminate, which comprises a step of curing.
[11] The method for producing a laminate according to [10], wherein the adherend is a transparent film, a transparent resin, or glass.
[12] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to [9] is irradiated with active energy rays and post-cured, and then has a post-cured pressure-sensitive adhesive layer and an adherend. Laminated body.

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer has post-curability and is excellent in processability when the pressure-sensitive adhesive layer is post-cured.

FIG. 1 is a schematic view showing a cross section of an example of the pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a schematic view showing a cross section of an example of the laminated body of the present invention. FIG. 3 is a schematic view showing a cross section of another example of the laminated body of the present invention.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

In the present specification, "(meth) acrylate" represents both acrylate and methacrylate, or either, and "(meth) acrylic acid" represents both acrylic acid and methacrylic acid, or either.
Further, in the present specification, "monomer" and "monomer" are synonymous.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state.
The pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a crosslinker, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator.
The glass transition temperature (Tg) of the homopolymer when the monomer is polymerized is 30 ° C. or higher.
The pressure-sensitive adhesive layer is post-curable and
When the pressure-sensitive adhesive layer is post-cured, it satisfies the following physical property group (1).
Physical property group (1): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 1 × 10 ⁶ [Pa] or more, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or more, and the probe tack value measured at 23 ° C. and the following measurement conditions is 1.5 N / 5 mmφ or less.
(Measurement conditions for probe tack value)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5 mmφ
Probe base material: Stainless steel surface finish AA # 400 Mirror surface weight by polishing: 19.6 ± 0.2 g (made of brass)
Probe moving speed: 1.0 cm / sec Duel time: 1 sec.
With this configuration, the pressure-sensitive adhesive sheet of the present invention has excellent processability when the pressure-sensitive adhesive layer is post-curable and the pressure-sensitive adhesive layer is post-cured. When the pressure-sensitive adhesive layer is post-cured, the shear storage elastic modulus G'is above a specific range at 23 ° C. and 75 ° C., so that the hardness becomes good in workability.
Further, when the pressure-sensitive adhesive layer is post-cured, the probe tack value is below a specific range at 23 ° C., for example, the pressure-sensitive adhesive adheres to the punching blade during punching, and the pressure-sensitive adhesive layer is deformed accordingly. It can be prevented.

<Structure of adhesive sheet>
First, the configuration of the adhesive sheet of the present invention will be briefly described. FIG. 1 is a schematic view showing a cross section of an example of the pressure-sensitive adhesive sheet of the present invention.
The pressure-sensitive adhesive sheet 1 of the present invention has a pressure-sensitive adhesive layer 11. The pressure-sensitive adhesive sheet 1 may be a single-layer pressure-sensitive adhesive sheet composed of only the pressure-sensitive adhesive layer 11. Further, the pressure-sensitive adhesive sheet may be a single-sided pressure-sensitive adhesive sheet having a base material (preferably a transparent base material) on one side, or a double-sided pressure-sensitive adhesive sheet.
As shown in FIG. 1, the single-sided pressure-sensitive adhesive sheet has a structure in which the transparent base material 12a is provided on one side of the pressure-sensitive adhesive layer 11. The other surface of the pressure-sensitive adhesive layer 11 is preferably covered with a release sheet 12b. When this pressure-sensitive adhesive sheet is used, it is preferable to peel off the release sheet 12b, attach the pressure-sensitive adhesive layer 11 to a desired adherend so that the pressure-sensitive adhesive layer 11 adheres to the desired adherend, and then perform post-curing by irradiation with energy rays or the like. As the transparent base material, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film can be used. Further, an easy-adhesion layer may be provided on the pressure-sensitive adhesive layer side of these transparent substrates. Further, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, and an ultraviolet absorbing layer may be provided on the opposite surface of the adhesive layer of the transparent base material.
The double-sided adhesive sheet includes a single-layer adhesive sheet composed of an adhesive layer, a multi-layer adhesive sheet in which a plurality of adhesive layers are laminated, and a multi-layer adhesive in which another adhesive layer is laminated between the adhesive layers. A multi-layered pressure-sensitive adhesive sheet in which a support is laminated between a sheet, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive layer, and a multi-layered pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one side of the support and another pressure-sensitive adhesive layer is laminated on the other side. Can be mentioned. When the double-sided adhesive sheet has a support, it is preferable to use a transparent support as the support. As the support, a general film used in the optical field can be used as in the case of the transparent substrate. Since such a double-sided pressure-sensitive adhesive sheet is also excellent in transparency of the pressure-sensitive adhesive sheet as a whole, it can be suitably used for bonding optical members to each other.
The pressure-sensitive adhesive sheet of the present invention has a structure in which a pair of release sheets having different peeling forces (which are double-sided pressure-sensitive adhesive sheets) are provided on both sides of the pressure-sensitive adhesive layer, or a transparent substrate / pressure-sensitive adhesive (which is a single-sided pressure-sensitive adhesive sheet). A layer / release sheet configuration is more preferable. The pressure-sensitive adhesive sheet of the present invention is particularly preferably composed of a transparent base material / pressure-sensitive adhesive layer / release sheet (which is a single-sided pressure-sensitive adhesive sheet).

<Peeling sheet>
The surface of the pressure-sensitive adhesive layer 11 is preferably covered with a release sheet. That is, the adhesive sheet is preferably an adhesive sheet with a release sheet.
The pressure-sensitive adhesive layer 11 shown in FIG. 1 has a release sheet 12b (in the case of a double-sided pressure-sensitive adhesive sheet, 12a is also a release sheet), and FIG. 1 shows an example of the configuration of the pressure-sensitive adhesive sheet 1 with the release sheet. It represents.

The release sheet is a removable laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or polypropylene film as a low-polarity base material. Can be mentioned.
Papers and polymer films are used as the base material for the release sheet in the releaseable laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone type release agent or a long-chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
Specific examples of the silicone-based release agent include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Can be mentioned. Further, the silicone-based release agent may contain a silicone resin which is an organic silicon compound having ₂ units of SiO and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ = CH (CH ₃ ) SiO _1/2 units. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Co., Ltd.
A commercially available product may be used as the peelable laminated sheet. Examples include a heavy separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd., and a light separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd. it can.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it is preferable to have a pair of release sheets having different peeling forces. That is, it is preferable that the release sheet has different peelability between the release sheet 12a and the release sheet 12b in order to facilitate the release. When the peelability from one side and the peelability from the other side are different, it becomes easy to peel off only the release sheet having the higher peelability first. In that case, the peelability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding order.

<Adhesive layer>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state, the pressure-sensitive adhesive layer has post-curing property, and when the pressure-sensitive adhesive layer is post-cured, the above-mentioned physical property group ( 1) is satisfied.

(Physical properties and characteristics of the adhesive layer)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is a semi-cured state of the pressure-sensitive adhesive composition and has post-curability.
The fact that the pressure-sensitive adhesive layer is in a semi-cured state can be confirmed from the fact that the gel fraction is 0% by mass or more and less than 70% by mass. The gel fraction of the pressure-sensitive adhesive layer in the semi-cured state is preferably 2% by mass or more and less than 70% by mass, and particularly preferably 5 to 65% by mass.
It can be confirmed that the pressure-sensitive adhesive layer is after post-curing because the gel fraction is 70 to 100% by mass. When the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is particularly preferably 75 to 100% by mass.
The fact that the pressure-sensitive adhesive layer has post-curing property can be confirmed from the fact that when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 5% by mass or more higher than the gel fraction in the semi-cured state. .. When the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is preferably 10% by mass or more higher than the gel fraction in the semi-cured state, and more preferably 15% by mass or more.

For "semi-curing", it is preferable that the pressure-sensitive adhesive layer is first cured only by heat. The "semi-cured state" is preferably a soft pressure-sensitive adhesive layer after thermosetting and before irradiation with active energy rays. Further, in "post-curing", it is preferable that the pressure-sensitive adhesive layer is cured by active energy rays after being brought into a semi-cured state by heat.
That is, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is preferably in a semi-cured state by thermosetting the pressure-sensitive adhesive composition, and preferably has active energy ray-curability.

-Physical property group (1)-
In the present invention, the physical property group (1) is satisfied when the pressure-sensitive adhesive layer is post-cured.
Physical property group (1): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 1 × 10 ⁶ [Pa] or more, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × is at 10 ⁵ [Pa] or more, the probe tack value measured at 23 ° C. and above measurement conditions is less than 1.5 N / 5 mm.phi.
When the pressure-sensitive adhesive layer is post-cured, the shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is preferably 1.2 × 10 ⁶ [Pa] or more, and 1.5 × 10 ⁶ [Pa]. ] The above is more preferable. Upper limit of 23 ° C. and a shear storage modulus measured at a frequency 1 Hz G 'in the case where the pressure-sensitive adhesive layer is post-cured are not particularly limited and may be, for example, 1.0 × 10 ⁸ [Pa] or less ..
When the pressure-sensitive adhesive layer is post-cured, the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is preferably 1.5 × 10 ⁵ [Pa] or more, preferably 2.0 × 10 ⁵ [Pa]. ] The above is more preferable. Upper limit of 23 ° C. and a shear storage modulus measured at a frequency 1 Hz G 'in the case where the pressure-sensitive adhesive layer is post-cured are not particularly limited and may be, for example, 1.0 × 10 ⁸ [Pa] or less ..
When the pressure-sensitive adhesive layer is post-cured, the probe tack value measured at 23 ° C. and under the above-mentioned measurement conditions is preferably 1.0 N / 5 mmφ or less, and more preferably 0.5 N / 5 mmφ or less. When the pressure-sensitive adhesive layer is post-cured, the lower limit of the probe tack value measured at 23 ° C. and under the above-mentioned measurement conditions is not particularly limited, but can be, for example, 0.1 N / 5 mmφ or more.

-Physical property group (2)-
In the present invention, it is preferable that the pressure-sensitive adhesive layer satisfies the following physical property group (2) in a semi-cured state.
Physical property group (2): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 8 × 10 ⁵ [Pa] or less, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or less, and the probe tack value measured at 23 ° C. and the above measurement conditions is 2.0 N / 5 mmφ or more.
When the pressure-sensitive adhesive layer is in a semi-cured state, the shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is more preferably 5 × 10 ⁵ [Pa] or less, and 2 × 10 ⁵ [Pa] or less. Is particularly preferable. When the pressure-sensitive adhesive layer is in a semi-cured state, the lower limit of the shear storage elastic modulus G'measured at 23 ° C. and a frequency of 1 Hz is not particularly limited, and may be, for example, 1.0 × 10 ⁴ [Pa] or more. it can.
When the pressure-sensitive adhesive layer is in a semi-cured state, the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is more preferably 5 × 10 ⁴ [Pa] or less, and 3 × 10 ⁴ [Pa] or less. Is particularly preferable. When the pressure-sensitive adhesive layer is in a semi-cured state, the lower limit of the shear storage elastic modulus G'measured at 75 ° C. and a frequency of 1 Hz is not particularly limited, and may be, for example, 1.0 × 10 ³ [Pa] or more. it can.
When the pressure-sensitive adhesive layer is in a semi-cured state, the probe tack value measured at 23 ° C. and the above-mentioned measurement conditions is more preferably 2.5 N / 5 mmφ or more, and particularly preferably 3.0 N / 5 mmφ or more. preferable. When the pressure-sensitive adhesive layer is in a semi-cured state, the upper limit of the probe tack value measured at 23 ° C. and under the above-mentioned measurement conditions is not particularly limited, but can be, for example, 20.0 N / 5 mmφ or less. It is preferably 0 N / 5 mmφ or less.

-Workability-
The pressure-sensitive adhesive sheet of the present invention is also excellent in processability after post-curing. In particular, it is preferable that the peeling distance when the cut end is rubbed is small. For workability after post-curing, the shear storage elastic modulus G'when the pressure-sensitive adhesive layer is post-cured is set to a specific range or more, and the probe tack value when the pressure-sensitive adhesive layer is post-cured is set to a specific range or less. By doing so, it can be improved.

-Sticky end face-
The pressure-sensitive adhesive sheet of the present invention has less stickiness (tackiness) on the end face of the pressure-sensitive adhesive layer after post-curing. For the stickiness of the end face of the pressure-sensitive adhesive layer after post-curing, the shear storage elastic modulus G'when the pressure-sensitive adhesive layer is post-cured is set to a specific range or more, and the probe tack value when the pressure-sensitive adhesive layer is post-cured is set. It can be reduced by setting it below a specific range.

-Outgas resistance-
The pressure-sensitive adhesive sheet of the present invention preferably has excellent outgas resistance after post-curing. In particular, it is preferable that there are few bubbles and peeling after a long period of time in a high temperature and high humidity environment. The outgas resistance after post-curing should be improved by setting the shear storage elastic modulus G'in the semi-cured state to a specific range or less and the shear storage elastic modulus G'after post-curing to a specific range or more. Can be done.

(Thickness)
The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the intended use, and is not particularly limited, but is preferably in the range of 5 to 500 μm, more preferably 10 to 300 μm, and particularly preferably 12 to 100 μm. By setting the thickness of the pressure-sensitive adhesive layer within the above range, it is possible to sufficiently suppress the generation of air bubbles from an adherend such as a base material. In addition, it is excellent in workability because it can suppress the stickiness and stickiness of the adhesive. Further, by setting the thickness of the pressure-sensitive adhesive layer within the above range, the production of a double-sided pressure-sensitive adhesive sheet becomes easy.

<Adhesive composition>
The above-mentioned pressure-sensitive adhesive layer is a semi-cured state of the pressure-sensitive adhesive composition.
In the present invention, the pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a crosslinker, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator. Here, the glass transition temperature (Tg) of the homopolymer when a monomer having at least one reactive double bond in the molecule is polymerized is 30 ° C. or higher.
The pressure-sensitive adhesive composition used in the present invention is preferably a dual-curable pressure-sensitive adhesive composition.

(Crosslinkable acrylic polymer)
In the present invention, the pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer.
The crosslinkable acrylic polymer is not particularly limited, but preferably contains a non-crosslinkable (meth) acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group. The crosslinkable acrylic polymer preferably has transparency to the extent that it does not reduce the visibility of the display device. In addition, in this specification and claims, a "unit" is a repeating unit (monomer unit) constituting a polymer.

The non-crosslinkable (meth) acrylic acid ester unit (a1) is a repeating unit derived from the (meth) acrylic acid alkyl ester. Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and (meth). Isobutyl acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, ( Isooctyl acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, (meth) Examples thereof include n-dodecyl acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate. One of these may be used alone, or two or more thereof may be used in combination.
Among the above (meth) acrylic acid alkyl esters, at least one selected from methyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is selected because of its high adhesiveness. preferable.

In the present invention, the crosslinkable functional group of the crosslinkable acrylic polymer is preferably one or more selected from a carboxy group, a hydroxy group, an amino group, an amide group, a glycidyl group and an isocyanate group. More preferably, it is one or more selected from a carboxy group, a hydroxy group, an amino group and a glycidyl group.
The acrylic monomer unit (a2) having a crosslinkable functional group is preferably a carboxy group-containing monomer unit, a hydroxy group-containing monomer unit, an amino group-containing monomer unit, or a glycidyl group-containing monomer unit.
Examples of the carboxy group-containing monomer unit include acrylic acid and methacrylic acid.
The hydroxy group-containing monomer unit is a repeating unit derived from the hydroxy group-containing monomer. Examples of the hydroxy group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. Examples thereof include (meth) acrylic acid [(mono, di or poly) alkylene glycol] such as mono (meth) acrylic acid mono (diethylene glycol), and (meth) acrylic acid lactone such as (meth) acrylic acid monocaprolactone.
Examples of the amino group-containing monomer unit include repeating units derived from amino group-containing monomers such as (meth) acrylamide and allylamine.
Examples of the glycidyl group-containing monomer unit include repeating units derived from a glycidyl group-containing monomer such as glycidyl (meth) acrylate.

The content of the acrylic monomer unit (a2) having a crosslinkable functional group in the crosslinkable acrylic polymer is preferably 0.01 to 40% by mass, more preferably 0.5 to 35% by mass. .. When the content of the acrylic monomer unit (a2) having a crosslinkable functional group is at least the lower limit of the above range, it has sufficient crosslinkability necessary for maintaining the semi-cured state, and is in the above range. If it is below the upper limit of, it is easy to maintain the required adhesiveness.

The crosslinkable acrylic polymer has, if necessary, a monomer unit other than the non-crosslinkable (meth) acrylic acid ester unit (a1) and the acrylic monomer unit (a2) having a crosslinkable functional group. You may. The other monomer may be copolymerizable with a non-crosslinkable (meth) acrylic acid ester and an acrylic monomer having a crosslinkable functional group, for example, (meth) acrylonitrile, vinyl acetate, styrene, chloride. Examples include vinyl, vinylpyrrolidone, vinylpyridine and the like. The content of the other monomer unit in the crosslinkable acrylic polymer is preferably 0 to 20% by mass, more preferably 0 to 15% by mass.

The weight average molecular weight of the crosslinkable acrylic polymer is preferably 10 to 2 million, more preferably 300 to 1.5 million. When the weight average molecular weight is within the above range, it is easy to maintain the semi-cured state of the pressure-sensitive adhesive sheet, and it is easy to obtain the hardness after post-curing, and the processability is excellent. The weight average molecular weight of the crosslinkable acrylic polymer is a value before being crosslinked with a crosslinking agent. The weight average molecular weight is a value measured by size exclusion chromatography (SEC) and determined based on polystyrene. As the crosslinkable acrylic polymer, a commercially available one may be used, or one synthesized by a known method may be used.

(Crosslinking agent)
In the present invention, the pressure-sensitive adhesive composition contains a cross-linking agent.
The cross-linking agent can be appropriately selected in consideration of the reactivity of the cross-linking acrylic polymer with the cross-linking functional group. For example, it can be selected from known cross-linking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds and butylated melamine compounds. Among these, an isocyanate compound and an epoxy compound are preferable because the acrylic monomer unit (a2) having a crosslinkable functional group can be easily crosslinked. In the present invention, it is preferable that the cross-linking agent is one or more selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound.
For example, when a hydroxy group is contained as the crosslinkable functional group, it is more preferable to use an isocyanate compound because of the reactivity of the hydroxy group.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like.
Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol di. Glycidyl ether, tetraglycidyl xylenediamine, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, trimethylolpropan polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.
A commercially available product can be used as the cross-linking agent. Examples of commercially available products include tolylene diisocyanate compounds (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L), xylylene diisocyanate compounds (manufactured by Mitsui Chemicals, Inc., Takenate D-110N) and the like.

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected according to the desired tackiness and the like, but is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the cross-linking acrylic polymer, and is 0. .1 to 3 parts by mass is more preferable. When the content of the cross-linking agent is at least the above lower limit value, the shear storage elastic modulus G'in the semi-cured state can be adjusted to a desired range, so that the processability is excellent. When it is at least the above upper limit value, the initial substrate adhesion Therefore, it does not come off even if it is rubbed by hand after post-curing, and it has excellent workability.
As the cross-linking agent, one type may be used alone or two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

(Monomer)
In the present invention, the pressure-sensitive adhesive composition contains a monomer having at least one reactive double bond in the molecule. Here, the glass transition temperature (Tg) of the homopolymer when the monomer is polymerized is 30 ° C. or higher. The glass transition temperature (Tg) of the homopolymer when the monomer is polymerized is preferably 40 ° C. or higher, more preferably 45 ° C. or higher.

The monomer may be a monofunctional monomer having one reactive double bond in the molecule, or a polyfunctional monomer having two or more reactive double bonds in the molecule. Good. Further, as the monomer, a monofunctional monomer and a polyfunctional monomer may be used in combination.

Examples of the monofunctional monomer include isobolonyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, stearyl methacrylate and the like.
A commercially available product can be used as the monofunctional monomer. Examples of commercially available products include IBXA manufactured by Osaka Organic Chemical Industry Co., Ltd.

The polyfunctional monomer has two or more reactive double bonds, and more preferably has three to six reactive double bonds.
Examples of the polyfunctional monomer include di (meth) acrylic acid ethylene glycol, di (meth) acrylic acid triethylene glycol, di (meth) acrylic acid 1,3-butylene glycol, and di (meth) acrylic acid 1,. 4-butylene glycol, di (meth) acrylic acid 1,9-nonanediol, diacrylic acid 1,6-hexanediol, di (meth) acrylic acid polybutylene glycol, di (meth) acrylic acid neopentyl glycol, di (meth) ) Tetraethylene glycol acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylol propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetra (meth) acrylic Examples thereof include (meth) acrylic acid esters of polyhydric alcohols such as pentaerythritol acid, vinyl methacrylate and the like.
Commercially available products can be used as the polyfunctional monomer. Examples of commercially available products include trimethylolpropane propylene oxide-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-321), a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (manufactured by Toagosei Co., Ltd., Aronix M-405) and the like.

In the present invention, the pressure-sensitive adhesive composition preferably contains the above-mentioned monomer by 5 to 40 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer, more preferably 15 to 40 parts by mass, and 25 to 40 parts by mass. It is particularly preferable to contain 35 parts by mass. The monomer may be used alone or in combination of two or more, and when two or more of them are used in combination, the total mass is preferably within the above range.

(Polymerization initiator)
In the present invention, the pressure-sensitive adhesive composition contains a polymerization initiator.
The polymerization initiator preferably has an ability to initiate polymerization by irradiation with active energy rays, and more preferably has an ability to initiate polymerization of the above-mentioned monomer. As the polymerization initiator, for example, a known one such as a photopolymerization initiator can be used.
Here, the "active energy ray" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

Examples of the polymerization initiator include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, amine-based initiators, acylphosphine oxide-based initiators, and the like. Be done.
Specific examples of the acetophenone-based initiator include diethoxyacetophenone and benzyl dimethyl ketal.
Specific examples of the benzoin ether-based initiator include benzoin and benzoin methyl ether.
Specific examples of the benzophenone-based initiator include benzophenone, methyl o-benzoylbenzoate, and the like.
Specific examples of the hydroxyalkylphenone-based initiator include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., commercially available as IRGACURE184) and the like.
Specific examples of the thioxanthone-based initiator include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone and the like.
Specific examples of the amine-based initiator include triethanolamine, ethyl 4-dimethylbenzoate and the like.
Specific examples of the acylphosphine oxide-based initiator include phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan Ltd., commercially available as IRGACURE819).

The content of the polymerization initiator in the pressure-sensitive adhesive composition is appropriately selected according to the content of the monomer, the irradiation amount of active energy rays at the time of post-curing, and the like. Specifically, it is preferably 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the total mass of the monomer. If it is at least the above lower limit value, the hardness can be adjusted to a desired level by post-curing, so that workability is excellent. When it is not more than the above upper limit value, the molecular weight after post-curing is not reduced, and the workability and outgas resistance are excellent.
As the polymerization initiator, one type may be used alone or two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

(solvent)
The pressure-sensitive adhesive composition may contain a solvent. In this case, the solvent is used to improve the coating suitability of the pressure-sensitive adhesive composition. Examples of the solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloropropane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol, diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone; methyl acetate , Ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate, etc .; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Examples thereof include polyols such as glycol monomethyl ether acetate and derivatives thereof.

The content of the solvent in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 25 to 500 parts by mass, more preferably 30 to 400 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer.
The content of the solvent is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the pressure-sensitive adhesive composition. One type of solvent may be used alone, two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

(Plasticizer)
The pressure-sensitive adhesive composition may further contain a plasticizer as long as the effects of the present invention are not impaired. When the pressure-sensitive adhesive composition contains a plasticizer, the pressure-sensitive adhesive sheet can fill the step formed on the adherend, and the unevenness-following property is enhanced. The plasticizer is preferably a non-functional acrylic polymer. The non-functional group acrylic polymer is a polymer consisting only of an acrylic monomer unit having no functional group other than an acrylate group, or a non-functional group having no functional group other than an acrylate group and an acrylic monomer unit having no functional group. It is a polymer composed of an acrylic monomer unit. Since the non-functional group acrylic polymer is not crosslinked, it is possible to improve the unevenness followability without affecting the adhesiveness.
Examples of the acrylic monomer unit having no functional group other than the acrylate group include those similar to the non-crosslinkable (meth) acrylic acid ester unit (a1).
Examples of the non-acrylic monomer unit having no functional group include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, and stearer. Examples thereof include vinyl carboxylic acid esters such as vinyl acetate, vinyl cyclohexanecarboxylate, vinyl benzoate, and styrene.

(Other ingredients)
The pressure-sensitive adhesive composition may contain components other than the above as long as the effects of the present invention are not impaired. Examples of other components include components known as additives for adhesives. For example, an antioxidant, a metal corrosion inhibitor, a tackifier, a silane coupling agent, an ultraviolet absorber, a light stabilizer such as a hindered amine compound, and the like can be selected as necessary.
Examples of the antioxidant include a phenol-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, and the like. One type of these antioxidants may be used alone, or two or more types may be used in combination.
As the metal corrosion inhibitor, a benzodiazole-based resin can be mentioned as a preferable example because of the compatibility and high effect of the pressure-sensitive adhesive.
Examples of the tackifier include rosin-based resin, terpene-based resin, terpene phenol-based resin, Kumaron inden-based resin, styrene-based resin, xylene-based resin, phenol-based resin, and petroleum resin.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto group-substituted alkoxy oligomer).
Examples of the ultraviolet absorber include benzotriazole-based compounds and benzophenone-based compounds. However, when ultraviolet rays are used for the active energy rays during post-curing, it is preferable to add them within a range that does not inhibit the polymerization reaction.

<Manufacturing method of adhesive sheet>
The method for producing the adhesive sheet is not particularly limited.
The method for producing the pressure-sensitive adhesive sheet preferably includes a step of applying the pressure-sensitive adhesive composition on the release sheet to form a coating film and a step of heating the coating film to make a cured product in a semi-cured state.
By heating the coating film, the reaction between the crosslinkable acrylic polymer and the crosslinker proceeds to form a cured product (adhesive layer) in a semi-cured state. That is, during heating, the polymerization reaction of the monomer by the polymerization initiator does not proceed in the coating film, or even if it progresses, it is slight, so that the single amount contained in the pressure-sensitive adhesive composition is contained in the pressure-sensitive adhesive layer. At least a part of the body and the polymerization initiator is contained in an unreacted state. The pressure-sensitive adhesive sheet of the present invention preferably has post-curability and active energy ray-curability.
In order to bring the pressure-sensitive adhesive composition into a semi-cured state, it is preferable to perform an aging treatment in which the pressure-sensitive adhesive sheet is allowed to stand at a constant temperature for a certain period of time after the solvent is removed after coating. The aging treatment can be performed, for example, by allowing it to stand at 23 ° C. for 7 days.

It is preferable that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention can be post-cured by irradiating an adherend such as a base material with active energy rays. The pressure-sensitive adhesive sheet of the present invention is a two-step curing pressure-sensitive adhesive sheet, and preferably has a pressure-sensitive adhesive layer semi-cured only by heat before bonding, and the pressure-sensitive adhesive layer can be post-cured by active energy rays after bonding. ..

The coating of the pressure-sensitive adhesive composition can be carried out using a known coating device. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater and the like.

A known heating device such as a heating furnace or an infrared lamp can be used for heating the coating film formed by applying the pressure-sensitive adhesive composition.

(How to use the adhesive sheet)
In the method of using the pressure-sensitive adhesive sheet of the present invention, it is preferable that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is brought into contact with the surface of the adherend.
In the method of using the pressure-sensitive adhesive sheet of the present invention, it is preferable that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is adhered to an adherend when it is in a semi-cured state, and the pressure-sensitive adhesive layer is post-cured by irradiating with active energy rays.

<Use of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention is preferably used for an optical member that requires durability, particularly an application that has a complicated shape and requires punching after forming a laminated body.
It is preferable that the pressure-sensitive adhesive sheet of the present invention can suppress the generation of air bubbles even when it is attached to an adherend such as a base material, post-cured, and then exposed to a high humidity and heat environment. The pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive sheet used for sticking to a base material, and more preferably a pressure-sensitive adhesive sheet used for sticking to a polycarbonate base material. Examples of the polycarbonate base material include PC-1151 manufactured by Teijin Chemicals Ltd.

The pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive sheet used for direct bonding to a base material, but may be used for indirectly bonding to a base material. For example, it may be bonded to a multilayer base material including a polycarbonate base material. Such a multilayer base material is preferably a base material having a polycarbonate layer and a hard coat layer. The composition of the hard coat layer is preferably selected from acrylic, urethane, silicone, melamine, and epoxy, and more preferably acrylic and silicone. The composition of the hard coat layer is more preferably acrylic from the viewpoint of workability and hardness. In addition, in this specification, a multilayer base material containing a polycarbonate base material is also referred to as a polycarbonate base material.
As the multilayer base material containing the polycarbonate base material, for example, MR-58 or IMR05 manufactured by Mitsubishi Gas Chemical Company, Inc. can be used. Here, the composition of MR-58 is HC (hard coat) / PMMA (polymethyl methacrylate) / PC (polycarbonate) / HC (hard coat). The overall thickness of MR-58 is preferably 0.3 mm to 1.2 mm, and the thickness of one hard coat layer is preferably 0.0005 mm to 0.02 mm. The composition of IMR05 is HC (hard coat) / PC (polycarbonate).

Further, the pressure-sensitive adhesive sheet of the present invention can suppress the occurrence of air bubbles and peeling even when it is attached to an optical member such as a polarizing plate, post-cured, and then exposed to a high humidity and heat environment. .. Here, the polarizing plate includes a polarizing element and a polarizer protective film, and the pressure-sensitive adhesive sheet of the present invention is preferably bonded to the polarizer protective film. The polarizer protective film includes a cycloolefin resin film, a cellulose acetate resin film such as triacetyl cellulose and diacetyl cellulose, a polyester resin film such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, a polycarbonate resin film, and acrylic. Examples thereof include a based resin film and a polypropylene resin film. In particular, when the polarizer protective film is a cellulose acetate-based resin film, the effect of suppressing the generation of bubbles is exhibited by using the pressure-sensitive adhesive sheet of the present invention.
In the present invention, since the generation of air bubbles in the adherend of the adhesive sheet can be suppressed, deterioration of visibility can be prevented when the adhesive sheet is incorporated in a display device or the like.

It is preferable that the semi-cured adhesive sheet is attached to the adherend so that the unevenness can be followed. Further, the adhesive strength and the holding power can be enhanced by post-curing the pressure-sensitive adhesive layer by irradiation with active energy rays.

[Laminate]
The laminate of the present invention has a pressure-sensitive adhesive layer after curing by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention with active energy rays and then curing, and an adherend.
The pressure-sensitive adhesive sheet contained in the laminate is post-cured by irradiating active energy rays with two adherends (for example, a base material and an optical member) bonded together with a semi-cured pressure-sensitive adhesive sheet. It is preferable to have.

FIG. 2 is a schematic view showing a cross section of an example of the laminated body of the present invention. FIG. 2 is a cross-sectional view showing an example of the configuration of the laminated body 20 in which the pressure-sensitive adhesive sheet 21 of the present invention is bonded to the base material 22 and the optical member 24. As shown in FIG. 2, the pressure-sensitive adhesive sheet 21 of the present invention is preferably used for bonding to the base material 22, and may be used for bonding the base material 22 and another optical member 24. preferable. The pressure-sensitive adhesive sheet 21 of the present invention may be used for bonding with a polarizing plate.

Examples of the optical member included in the laminate include each component in an optical product such as a touch panel and an image display device. Examples of the constituent members of the touch panel include an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, and a transparent conductive film in which a transparent resin film is coated with a conductive polymer. Examples include hard coat films and fingerprint resistant films. Examples of the constituent members of the image display device include antireflection films, alignment films, polarizing films, retardation films, and luminance improving films used in liquid crystal display devices.
Examples of the material used for these members include glass, polycarbonate, polyethylene terephthalate, polymethylmethacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, cellulose acylate and the like.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it can be used for bonding two adherends. In this case, the adhesive sheet of the present invention is used for bonding transparent optical films inside the touch panel, bonding the transparent optical film and glass, bonding the transparent optical film of the touch panel to the liquid crystal panel, and covering glass. It is used for bonding the transparent optical film and the cover glass, and it is preferable that any of the members is a polycarbonate base material. As the transparent optical film, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film can be used. Further, a hard coat layer may be provided on the transparent optical film or the polycarbonate base material.

FIG. 3 is a schematic view showing a cross section of another example of the laminated body of the present invention. As shown in FIG. 3, the adherend may have stepped portions (27a, 27b, 27c, 27d). In FIG. 3, the base material has a stepped portion (27a, 27b), and the optical member has a stepped portion (27c, 27d). The thickness of the stepped portion (27a, 27b, 27c, 27d) is usually 5 to 60 μm. As described above, the adhesive sheet 21 of the present invention can be attached to a member having a stepped portion, and can follow the unevenness generated from the stepped portion.

[Manufacturing method of laminate]
The method for producing a laminate of the present invention is a step of attaching the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention to an adherend in a semi-cured state and then irradiating an active energy ray to post-cure the pressure-sensitive adhesive layer. including.
In the present invention, it is preferable to include a step of bringing the semi-cured pressure-sensitive adhesive sheet into contact with the surface of the adherend and irradiating the surface of the adherend with active energy rays in that state to post-curing the pressure-sensitive adhesive layer.
The adherend is more preferably a base material and an optical member, and particularly preferably a polycarbonate base material, a polarizing plate, a transparent film, a transparent resin or glass. In the present invention, it is more preferable that the adherend is a transparent film, a transparent resin or glass.

When the pressure-sensitive adhesive sheet is attached to the base material and the optical member, the active energy rays can be irradiated from either the base material side or the optical member side, but it is preferable to irradiate from the base material side.
Since the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state before irradiation with the active energy rays, the pressure-sensitive adhesive layer can follow the unevenness even if the adherend has a stepped portion. In this way, the adhesive sheet is attached to each other to follow the unevenness, and then the adhesive layer is post-cured with active energy rays to increase the cohesive force of the adhesive layer and improve the adhesiveness to the adherend. To do. In addition, the post-cured pressure-sensitive adhesive layer can prevent the base material from being deformed or distorted.

Examples of the active energy ray include ultraviolet rays, electron beams, visible rays, X-rays, ion rays and the like, which can be appropriately selected depending on the polymerization initiator contained in the pressure-sensitive adhesive layer. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.
As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp and the like can be used.
As the electron beam, for example, an electron beam emitted from each type of electron beam accelerator such as Cockloft Wald type, Bandecliff type, Resonant transformer type, Insulated core transformer type, Linear type, Dynamitron type, High frequency type is used. it can.
Radiation output of the UV, integrated light quantity is preferably to be a 100~10000mJ / cm ^2, and more preferably made to be 500~5000mJ / cm ^2.

The features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.

[Manufacturing Example 1]
A crosslinkable acrylic polymer was prepared by solution polymerization in ethyl acetate. 2-Hydroxyethyl acrylate monomer, n-butyl acrylate monomer, and dimethylacrylamide are blended in a mass ratio of 0.5: 10: 2.5, and AIBN (azobisisobutyronitrile) is used as a radical polymerization initiator. Was dissolved in the solution. The solution was heated to 60 ° C. and randomly copolymerized to obtain a crosslinkable acrylic polymer A. The solution viscosity of the 35% by mass solution of the crosslinkable acrylic polymer at 23 ° C. was 5500 mPa · s.

[Manufacturing Example 2]
A crosslinkable acrylic polymer B was obtained in the same manner as in Production Example 1 above except that the 2-hydroxyethyl acrylate monomer was changed to acrylic acid.

[Example 1]
0.2 parts by mass of a xylylene diisocyanate compound (Takenate D-110N, manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent with respect to 100 parts by mass of the crosslinkable acrylic polymer A, and the glass transition temperature (Tg) when a homopolymer is used. ) Is 20 parts by mass of isoboronyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., IBXA, Tg = 94 ° C.) and trimethylolpropane propylene oxide-modified triacrylate (manufactured by Toa Synthetic Co., Ltd.) as a monomer having a temperature of 30 ° C. or higher. Aronix M-321 (Tg 50 ° C.) was added in an amount of 10 parts by mass, and 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Co., Ltd., IRGACURE184) was added in an amount of 1.12 parts by mass as a polymerization initiator, and the solid content concentration was 30. Ethyl acetate was added as a solvent so as to have a mass%, and a pressure-sensitive adhesive composition was obtained.

The pressure-sensitive adhesive composition was applied onto a first release sheet (heavy separator film, Teijin DuPont Film Co., Ltd., release-treated polyethylene terephthalate film). The coating was performed using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. so that the thickness after drying was 50 μm. Then, it was dried in a hot air dryer at 100 ° C. for 3 minutes to remove the solvent, and a pressure-sensitive adhesive sheet having a semi-cured pressure-sensitive adhesive layer was formed.
A second release sheet (light separator film, manufactured by Teijin DuPont Film Co., Ltd.), which has been subjected to a mold release treatment higher than the first release sheet, is attached to one side of this adhesive sheet, and the adhesive with the release sheet is attached. An adhesive sheet of Example 1 which is a sheet was obtained.

[Example 2]
Trimethylolpropanepropylene oxide-modified triacrylate (manufactured by Toa Synthetic Co., Ltd., Aronix M-321, Tg 50 ° C.) and 15 parts by mass of a monomer having a glass transition temperature (Tg) of 30 ° C. or higher when homopolymerized is used. A EO-modified diacrylate (M-211B, Tg = 75 ° C., manufactured by Toa Synthetic Co., Ltd.) was changed to 15 parts by mass, and the polymerization initiator was phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BASF Japan). An adhesive sheet of Example 2 was obtained in the same manner as in Example 1 except that it was changed to IRGACURE819 manufactured by Co., Ltd.

[Comparative Example 1]
Monomer having a glass transition temperature (Tg) of 30 ° C. or higher when homopolymerized is changed to 3 parts by mass of trimethylolpropane propylene oxide-modified triacrylate (manufactured by Toa Synthetic Co., Ltd., Aronix M-321, Tg 50 ° C.) Then, 6 parts by mass of isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., ISTA, Tg = -18 ° C.) was added as a monomer having a glass transition temperature (Tg) of less than 30 ° C. when homopolymerized. An adhesive sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 2]
The crosslinkable acrylic polymer A was changed to the crosslinkable acrylic polymer B, and the crosslinking agent was changed to the epoxy compounds N, N, N', N'-tetraglycidyl-m-xylene diamine (Mitsubishi Gas Chemical Co., Ltd., trade name Tetrad). A pressure-sensitive adhesive sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that the mixture was changed to X) and no monomer and polymerization initiator were used.

[Evaluation]
<Shear storage elastic modulus G'>
Four pressure-sensitive adhesive sheets (one sheet of 50 μm) were superposed so that the pressure-sensitive adhesive layer was 200 μm, and a sample for measurement in a semi-cured state was prepared.
Four pressure-sensitive adhesive sheets (one sheet of 50 μm) are laminated so that the pressure-sensitive adhesive layer is 200 μm, and ultraviolet rays are irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light intensity is 3000 mJ / cm ^2. , A sample for measurement after post-curing was prepared.
For the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of each measurement sample, a dynamic viscoelastic device Rheogel-E4000 (manufactured by UBM Co., Ltd.) was used at 0 ° C. under the conditions of solid shear mode, frequency 1 Hz, and strain 0.1%. The shear storage elastic modulus G'of the pressure-sensitive adhesive layer in the temperature range up to ~ 150 ° C. was measured.
The shear storage elastic modulus G'of the pressure-sensitive adhesive layer at 23 ° C. and 75 ° C. is shown in Table 1 below.

<Gel fraction>
Similar to the measurement of shear storage elastic modulus G', a measurement sample in a semi-cured state and a measurement sample after post-curing were prepared.
About 0.1 g of an adhesive sheet of each measurement sample was collected in a sample bottle, 30 ml of ethyl acetate was added, and the mixture was shaken for 24 hours. Then, the contents of this sample bottle were filtered by a 150 mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100 ° C. for 1 hour to measure the dry weight W (g). From the obtained dry weight, the gel fraction was calculated by the following formula 1.
Gel fraction (mass%) = (dry weight / collected weight of adhesive sheet) x 100 ... Equation 1

<Probe tack value>
The second release sheet, which is a light separator film of the adhesive sheet, was peeled off and attached to a PET film to prepare a sample for measurement in a semi-cured state.
Similarly, the second release sheet, which is a light separator film of the adhesive sheet, was peeled off and attached to the PET film. Next, ultraviolet rays were irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light intensity was 3000 mJ / cm ^2, and a sample for measurement after post-curing was prepared.
Each measurement sample was cut into 3 cm × 3 cm and measured with a probe tack tester under the following conditions.
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5 mmφ
Probe base material: Stainless steel surface finish AA # 400 Mirror surface weight by polishing: 19.6 g (made of brass)
Probe movement speed: 1.0 cm / sec Duel time: 1 sec

<Sticky end face>
Fifty A4 size adhesive sheets irradiated with ultraviolet rays from the side of the first release sheet, which is a heavy separator film, so that the integrated light intensity was 3000 mJ / cm ² , were superposed to prepare a sample for cutting after post-curing.
The guillotine blade when the adhesive sheet used as a sample for cutting after post-curing was cut by a guillotine cutting machine, and the end surface which is the cutting surface of the adhesive sheet were visually judged.
The adhesive does not squeeze out from the end face, which is the cutting surface of the adhesive sheet, and the guillotine blade and the end face, which is the cutting surface, are not sticky and are good ... ○
The adhesive squeezes out severely from the end face, which is the cutting surface of the adhesive sheet, and the guillotine blade and the end face stickiness, which is the cutting surface, are at a level that poses a practical problem ...

<Workability>
First, the second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and bonded to a PET film having a thickness of 25 μm.
Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC plate. The sample having the composition of PET / adhesive layer / PC is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are irradiated from the PET film side so that the integrated light intensity is 3000 mJ / cm2, and the test sample is prepared. Obtained. Next, the end portion of the test sample was cut using a guillotine cutting machine, and the cut end portion was rubbed by hand so as to peel off the PET film from the PC plate side. The peeling at that time was measured.
Peeling distance is less than 0.05 mm ... ◎
Peeling distance is 0.05 mm or more and less than 0.1 mm ... 〇 Peeling distance is 0.1 mm or more ... ×

<Outgas resistance>
First, the second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and bonded to a PET film having a thickness of 50 μm.
Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC plate. The sample having the composition of PET / adhesive layer / PC is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are irradiated from the PET film side so that the integrated light intensity is 3000 mJ / cm2, and the test sample is prepared. Obtained. The test sample was placed in an environment of 105 ° C. dry and 85 ° C. 85%, and bubbles and peeling were observed after 500 hours.
No bubbles or peeling is observed in either environment ... ○
Bubbles and peeling are observed in at least one environment ... ×

From Table 1 above, it was found that the pressure-sensitive adhesive sheet of the present invention has excellent workability when the pressure-sensitive adhesive layer is post-curable and the pressure-sensitive adhesive layer is post-cured. The pressure-sensitive adhesive sheet of the present invention also had good end face stickiness and outgas resistance.
From Comparative Example 1, it was found that when the pressure-sensitive adhesive layer after post-curing is less than the lower limit of the shear storage elastic modulus specified in the present invention, the processability is inferior when the pressure-sensitive adhesive layer is post-cured.
From Comparative Example 2, when the pressure-sensitive adhesive layer after post-curing is below the lower limit of the shear storage elastic modulus specified in the present invention and exceeds the upper limit of the probe tack value, it is processed when the pressure-sensitive adhesive layer is post-cured. It turned out to be inferior in sex.

1 Adhesive sheet 11 Adhesive layer 12a Transparent base material or release sheet 12b Release sheet 20 Laminated body 21 Adhesive sheet 22 Base material 24 Optical members 27a, 27b, 27c, 27d Steps

Claims (12)

It has a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state.
The pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a crosslinker, a monomer having at least one reactive double bond in the molecule, and a polymerization initiator.
The glass transition temperature (Tg) of the homopolymer when the monomer is polymerized is 30 ° C. or higher.
The pressure-sensitive adhesive layer has post-curing properties and is
An adhesive sheet that satisfies the following physical property group (1) when the pressure-sensitive adhesive layer is post-cured.
Physical property group (1): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 1 × 10 ⁶ [Pa] or more, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or more, and the probe tack value measured at 23 ° C. and the following measurement conditions is 1.5 N / 5 mmφ or less.
(Measurement conditions for probe tack value)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5 mmφ
Probe base material: Stainless steel surface finish AA # 400 Mirror surface weight by polishing: 19.6 ± 0.2 g (made of brass)
Probe moving speed: 1.0 cm / sec Duel time: 1 sec. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer satisfies the following physical property group (2) in a semi-cured state.
Physical property group (2): Shear storage elastic modulus G'measured at 23 ° C. and frequency 1 Hz is 8 × 10 ⁵ [Pa] or less, and shear storage elastic modulus G'measured at 75 ° C. and frequency 1 Hz is 1. × 10 ⁵ [Pa] or less, and the probe tack value measured at 23 ° C. and the above measurement conditions is 2.0 N / 5 mmφ or more. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 70 to 100% by mass. The gel fraction of the pressure-sensitive adhesive layer in the semi-cured state is 0% by mass or more and less than 70% by mass, and
The adhesive according to any one of claims 1 to 3, wherein when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 5% by mass or more higher than the gel fraction in the semi-cured state. Sheet. The crosslinkable functional group of the crosslinkable acrylic polymer is one or more selected from a carboxy group, a hydroxy group, an amino group, an amide group, a glycidyl group and an isocyanate group, according to claims 1 to 4. The adhesive sheet according to any one item. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the cross-linking agent is one or more selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive composition contains 5 to 40 parts by mass of the monomer with respect to 100 parts by mass of the crosslinkable acrylic polymer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the polymerization initiator has an ability to initiate polymerization by irradiation with active energy rays. The invention according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive layer has a pair of release sheets having different peeling forces on both sides of the pressure-sensitive adhesive layer, or a transparent base material / the pressure-sensitive adhesive layer / a release sheet. Adhesive sheet. After the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 9 is attached to an adherend in a semi-cured state, the pressure-sensitive adhesive layer is post-cured by irradiating with active energy rays. A method for producing a laminate, which comprises a step of causing the laminate. The method for producing a laminate according to claim 10, wherein the adherend is a transparent film, a transparent resin, or glass. A laminated body having an adhesive layer after curing after irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 9 with active energy rays and then curing, and an adherend.

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