JP6724946B2 - Pressure-sensitive adhesive sheet, pressure-sensitive adhesive sheet with release sheet, pressure-sensitive adhesive sheet with transparent film, laminate and method for producing laminate - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet with a release sheet, a pressure-sensitive adhesive sheet with a transparent film, a laminate, and a method for producing a laminate.

BACKGROUND ART Conventionally, a display device such as a liquid crystal display (LCD) and an input device used in combination with a display device such as a touch panel have been widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for the purpose of bonding optical members, and transparent adhesive sheets are also used for bonding display devices and input devices. ..

It is known that there are several methods of polymerizing the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive sheet, as described below. Specifically, two stages of (1) heat-induced polymerization, (2) active energy ray-induced polymerization, (3) heat (or active energy ray-induced) polymerization, and then active energy ray (or heat)-induced polymerization There is a method such as polymerization, (4) two-stage polymerization in which polymerization by active energy rays is performed and then polymerization by active energy rays.

In recent years, as a method for forming a pressure-sensitive adhesive sheet used for the above-mentioned applications, (3) two-stage polymerization in which polymerization by heat (or active energy rays) is performed and then polymerization by active energy rays (or heat) is performed. A method of curing may be used. Such a pressure-sensitive adhesive sheet is formed from, for example, a pressure-sensitive adhesive composition having both thermosetting property and active energy ray-curable property (hereinafter, may be referred to as “dual curable pressure-sensitive adhesive composition”). It has thermosetting and active energy ray curability. For this reason, before bonding with the adherend, temporary bonding can be performed by, for example, only heat curing, and then further curing with active energy rays (referred to as post-curing or after-curing). Can firmly adhere to the body.

For example, in Patent Document 1, 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 lauryl acrylate (b1). Containing a monomer (B), a cross-linking agent (C) that reacts with the base polymer (A) by heat, and a polymerization initiator (D that initiates a polymerization reaction of the monomer (B) by irradiation with an active energy ray. ) And a solvent (E), the pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive layer obtained by semi-curing by heating.
In Patent Document 2, as a plate material, glass plates are bonded to each other, at least two glass plates and synthetic resin plates or synthetic resin plates are bonded together with a pressure-sensitive adhesive sheet having at least one ultraviolet-curable pressure-sensitive adhesive layer, and then the plate material is used. It describes a method for producing a transparent laminate in which the pressure-sensitive adhesive layer is UV-cured by irradiating UV rays from the side.

JP, 2016-084391, A JP 2012-031059 A

When the present inventors have examined the characteristics of the pressure-sensitive adhesive sheets described in Patent Documents 1 and 2, when the workability of the pressure-sensitive adhesive sheet after post-curing is increased, high temperature durability may not be sufficiently exhibited. I understood.
Therefore, in order to solve such a problem of the conventional technique, the present inventors have proceeded with a study for the purpose of improving high temperature durability in a pressure-sensitive adhesive sheet having post-curing property and processability.

As a result of intensive studies to solve the above problems, the present inventors, in the pressure-sensitive adhesive sheet having a semi-cured pressure-sensitive adhesive layer, the post-cured pressure-sensitive adhesive layer to satisfy predetermined physical properties It was found that the post-curing pressure-sensitive adhesive layer can exhibit excellent processability and high temperature durability.
Specifically, the present invention has the following configurations.

[1] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer obtained by semi-curing a pressure-sensitive adhesive composition,
An adhesive sheet satisfying the following physical properties (1) to (3) when it is post-cured by irradiating the adhesive layer with active energy rays so that the integrated light amount becomes 3000 mJ/cm ² .
Physical properties (1): Tensile storage elastic modulus E′ measured at 23° C. and frequency 1 Hz is 5.0×10 ⁶ Pa or more, and tensile storage elastic modulus E′ measured at 85° C. and frequency 1 Hz is 3. 0×10 ⁵ Pa or more;
Physical properties (2): The probe tack value measured under the following measurement conditions at 23° C. is 1.0 N/5 mmφ or less;
(Probe tack value measurement conditions)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 Mirror surface weight by polishing: 19.6±0.2g (made of brass)
Probe moving speed: 1.0 cm/sec Dwell time: 1 sec Physical properties (3): Constant load peel distance at 23° C. measured under the following measurement condition (a) is 20 mm or less, measured under the following measurement condition (b) The constant load peel distance at 85° C. is 100 mm or less:
(Measurement condition (a))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. In an environment of 23° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 300 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 30 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 23° C.;
(Measurement condition (b))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. Under an environment of 85° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 100 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 10 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 85°C.
[2] The pressure-sensitive adhesive sheet according to [1], wherein the pressure-sensitive adhesive layer satisfies the following physical properties (4) in a semi-cured state:
Physical properties (4): Shear storage elastic modulus G′ measured at 23° C. and frequency 1 Hz is 8.0×10 ⁵ Pa or less, and shear storage elastic modulus G′ measured at 85° C. and frequency 1 Hz is 1. It is 0×10 ⁵ Pa or less.
[3] The adhesive composition has a crosslinkable acrylic polymer, a crosslinker, a polyfunctional monomer having two or more reactive double bonds in the molecule, and a monofunctional compound having one reactive double bond in the molecule Contains a monomer and a polymerization initiator,
The polyfunctional monomer is the pressure-sensitive adhesive sheet according to [1] or [2], which has a bisphenol skeleton in one molecule.
[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the gel fraction after post-curing is 65 to 100 mass% when the pressure-sensitive adhesive layer is post-cured.
[5] The gel fraction in the semi-cured state of the pressure-sensitive adhesive layer is 10% by mass or more and less than 70% by mass, and
The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein when the pressure-sensitive adhesive layer is post-cured, the gel fraction after post-curing is 10% by mass or more higher than the gel fraction in the semi-cured state.
[6] The pressure-sensitive adhesive sheet according to any one of [3] to [5], wherein the crosslinking agent is a bifunctional or higher functional isocyanate compound.
[7] The total content of the monofunctional monomer and the polyfunctional monomer is 6 to 50 parts by mass relative to 100 parts by mass of the crosslinkable acrylic polymer, [3] to [6]. Adhesive sheet.
[8] The pressure-sensitive adhesive sheet according to any one of [3] to [7], wherein the content of the polyfunctional monomer is 5 to 30 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer.
[9] The pressure-sensitive adhesive sheet according to any one of [3] to [8], wherein the monofunctional monomer is alkyl(meth)acrylate.
[10] The pressure-sensitive adhesive sheet according to any one of [3] to [9], wherein the polymerization initiator starts polymerization of the polyfunctional monomer and/or the monofunctional monomer by irradiation with active energy rays.
[11] A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different release forces on both surfaces of the pressure-sensitive adhesive sheet according to any one of [1] to [10].
[12] At least one selected from a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film on at least one surface of the pressure-sensitive adhesive sheet according to any one of [1] to [10]. An adhesive sheet with a transparent film, which comprises the transparent film of.
[13] A pressure-sensitive adhesive layer after post-curing, in which the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to [10] is irradiated with active energy rays to be post-cured, and a pressure-sensitive adhesive layer after post-curing. A laminate having an adherend on at least one surface side thereof.
[14] After the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of [1] to [10] is attached to an adherend in a semi-cured state, the pressure-sensitive adhesive layer is post-irradiated with active energy rays. A method for producing a laminate, which comprises a step of curing.

ADVANTAGE OF THE INVENTION According to this invention, the high temperature durability can be improved in the adhesive sheet which has a post-curing property and is processable.

FIG. 1 is a schematic view showing a cross section of a release sheet or an adhesive sheet having a base material. FIG. 2 is a diagram illustrating a method for measuring the constant load peeling distance. FIG. 3 is a schematic view showing a cross section of an example of the laminate of the present invention. FIG. 4 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 made based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In addition, in this specification, the numerical range represented using "-" means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit.

In addition, in this specification, "(meth)acrylate" represents both acrylate and methacrylate or either, and "(meth)acrylic acid" represents both acrylic acid and methacrylic acid.
Further, in the present specification, “monomer” and “monomer” have the same meaning, and “polymer” and “polymer” have the same meaning.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer obtained by semi-curing the pressure-sensitive adhesive composition. Here, the pressure-sensitive adhesive layer has post-curability, and when the pressure-sensitive adhesive layer is post-cured by irradiating the pressure-sensitive adhesive layer with active energy rays so that the integrated light amount becomes 3000 mJ/cm ² , the following physical properties (1) to (3) is satisfied.
Physical properties (1): Tensile storage elastic modulus E′ measured at 23° C. and frequency 1 Hz is 5.0×10 ⁶ Pa or more, and tensile storage elastic modulus E′ measured at 85° C. and frequency 1 Hz is 3. It is 0×10 ⁵ Pa or more.
Physical property (2): The probe tack value measured at 23° C. and the following measurement conditions is 1.0 N/5 mmφ or less.
(Probe tack value measurement conditions)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 Mirror surface weight by polishing: 19.6±0.2g (made of brass)
Probe moving speed: 1.0 cm/sec Dwell time: 1 sec Physical properties (3): Constant load peel distance at 23° C. measured under the following measurement condition (a) is 20 mm or less, measured under the following measurement condition (b) The constant load peel distance at 85° C. is 100 mm or less:
(Measurement condition (a))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. In an environment of 23° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 300 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 30 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 23°C.
(Measurement condition (b))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. Under an environment of 85° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 100 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 10 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 85°C.

With the above structure, in the present invention, the high-temperature durability of the pressure-sensitive adhesive sheet having post-curability and processability can be enhanced. In the present invention, the hardness of the pressure-sensitive adhesive layer after post-curing can be increased by satisfying the above conditions (1) and (2). Thereby, the stickiness (tackiness) of the end surface of the pressure-sensitive adhesive layer after post-curing can be suppressed to be low, and the workability of the pressure-sensitive adhesive layer can be improved. Further, in the present invention, the high temperature durability of the pressure-sensitive adhesive layer after post-curing can be enhanced by satisfying the above conditions (1) and (3).

In the present specification, a case where a triacetyl cellulose film is attached to one surface of a pressure-sensitive adhesive sheet and a polycarbonate plate is attached to the other surface of the pressure-sensitive adhesive sheet, and after being post-cured, the temperature is kept at 105° C. in a dry environment for 240 hours. Also, when the pressure-sensitive adhesive sheet is prevented from floating or peeling from the polycarbonate plate, it can be determined that it has excellent high-temperature durability.

Further, in the pressure-sensitive adhesive sheet of the present invention, post-curing end surface stickiness is suppressed, and for example, adhesion of the pressure-sensitive adhesive to the punching blade during punching and deformation of the pressure-sensitive adhesive layer accompanying it can be prevented. .. Furthermore, the pressure-sensitive adhesive sheet of the present invention does not cause deformation, protrusion, peeling, etc. of the pressure-sensitive adhesive layer when it is subjected to punching to a desired size after post-curing and then cutting for the purpose of aligning the end faces, and also has processability. Are better.

In the present invention, in order for the pressure-sensitive adhesive layer after post-curing to satisfy the above physical properties (1) to (3), for example, the pressure-sensitive adhesive composition is prepared by adding a crosslinkable acrylic polymer, a crosslinker, and a reactive diamine in the molecule. It is preferably composed of a polyfunctional monomer having two or more heavy bonds, a monofunctional monomer having one reactive double bond in the molecule, and a polymerization initiator. Further, the polyfunctional monomer more preferably has a bisphenol skeleton in one molecule. Since the pressure-sensitive adhesive composition contains a polyfunctional monomer having a bisphenol skeleton in one molecule, the hardness of the pressure-sensitive adhesive layer after post-curing can be increased. Thereby, the stickiness (tackiness) of the end surface of the pressure-sensitive adhesive layer after post-curing can be suppressed to be low, and the workability of the pressure-sensitive adhesive layer can be improved. In addition, by mixing various components so that the pressure-sensitive adhesive layer after post-curing satisfies the above physical properties (1) to (3), the tackiness of the semi-cured state can be suppressed while suppressing stickiness (tackiness). The wettability with respect to the base material can be enhanced. That is, the pressure-sensitive adhesive sheet of the present invention has the property that while it is highly adherent to the base material in the semi-cured state, it has a high hardness after post-curing, and thus can be easily end-face processed.

The breaking elongation of the pressure-sensitive adhesive layer after post-curing in a tensile test measurement at a pulling speed of 10 mm/min is preferably less than 800%, more preferably less than 600%. Here, the breaking elongation is measured according to JIS K7161-1. At that time, the tensile speed is 10 mm/min, and the measurement is performed at 23° C. and a relative humidity of 50%. As the measurement sample, an adhesive sheet (adhesive layer) having a thickness of 25 μm, a width of 60 mm and a length of 200 mm is rolled in the length direction and processed into a columnar shape having a cross-sectional area of 5 mm ² and a height of 60 mm. This is pulled so that the distance between chucks is 30 mm, and the elongation at which the sample breaks is defined as the breaking elongation. As the measuring device, for example, Autograph AGS-X manufactured by Shimadzu Corporation can be used.

<Structure of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet may be a single-layer pressure-sensitive adhesive sheet composed only of a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet may be a single-sided pressure-sensitive adhesive sheet having a substrate (preferably a transparent substrate) on one side, or a double-sided pressure-sensitive adhesive sheet. The double-sided pressure-sensitive adhesive sheet may be a single-layer pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer, a multi-layer pressure-sensitive adhesive sheet in which a plurality of pressure-sensitive adhesive layers are laminated, or a multi-layer pressure-sensitive adhesive in which another pressure-sensitive adhesive layer is laminated between pressure-sensitive adhesive layers. Sheet, multi-layered pressure-sensitive adhesive sheet in which a support is laminated between pressure-sensitive adhesive layers, and a multi-layered pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one side of a support and another pressure-sensitive adhesive layer is laminated on the other side Are listed. When the double-sided pressure-sensitive 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, like the transparent substrate, can be used. Since such a double-sided PSA sheet is excellent in transparency as a whole PSA sheet, it can be suitably used for bonding optical members to each other.

When the pressure-sensitive adhesive sheet of the present invention is a single-sided pressure-sensitive adhesive sheet, as shown in FIG. 1, the pressure-sensitive adhesive layer 11 may be provided with a transparent base material 12a on one surface thereof. In this case, the other surface of the adhesive layer 11 is preferably covered with the release sheet 12b. When using a pressure-sensitive adhesive sheet, the release sheet 12b may be peeled off and bonded so that the pressure-sensitive adhesive layer 11 adheres to a desired adherend, and then post-curing may be performed by irradiating with active energy rays. preferable. As the transparent substrate, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, 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 surface of the transparent substrate opposite to the adhesive layer.

The present invention may relate to a pressure-sensitive adhesive sheet with a release sheet, which comprises release sheets on both surfaces of the pressure-sensitive adhesive sheet. When the release sheet is provided on both surfaces of the pressure-sensitive adhesive sheet of the present invention, it is preferable to have release sheets 12a and 12b on both surfaces of the pressure-sensitive adhesive layer 11 as shown in FIG.

As the release sheet, a peelable laminated sheet having a release sheet base material and a release agent layer provided on one surface of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity base material. Are listed.
Papers and polymer films are used as the release sheet base material in the release laminate 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., KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Are listed. Further, the silicone release agent may contain a silicone resin which is an organosilicon compound having SiO ₂ units 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 manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3800, X92-183 manufactured by Shin-Etsu Chemical Co., Ltd.
A commercially available product may be used as the peelable laminated sheet. For example, a heavy separator film which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Co., Ltd. and a light separator film which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Co., Ltd. may be mentioned. 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 releasability between the release sheet 12a and the release sheet 12b in order to facilitate the release. When the releasability from one side and the releasability from the other are different, it becomes easier to first release only the release sheet having the higher releasability. In that case, the releasability of the release sheet 12a and the release sheet 12b may be adjusted according to the attaching method and the attaching order.

The present invention may also be directed to a pressure-sensitive adhesive sheet with a transparent film, which comprises a transparent film on at least one surface of the pressure-sensitive adhesive sheet. In this case, the transparent film is preferably at least one selected from polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film and cycloolefin polymer film. The transparent film-attached pressure-sensitive adhesive sheet may be a sheet in which a transparent film/pressure-sensitive adhesive sheet/release sheet are laminated in this order.

<Adhesive layer>
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer obtained by semi-curing the pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer has post-curability.

Here, in the present specification, when the gel fraction of the pressure-sensitive adhesive layer is increased by 10% by mass or more by irradiating or heating the active energy ray under the following conditions, the pressure-sensitive adhesive layer before irradiation or heating is It is assumed to be in a cured state. In this case, when the pressure-sensitive adhesive layer is post-cured by irradiating with active energy rays, an optical transparent PET separator is attached to both surfaces of the pressure-sensitive adhesive layer, and the active energy ray (high pressure mercury lamp is used from the optical transparent PET separator side. Or a metal halide lamp) so that the integrated light amount becomes 3000 mJ/cm ² . When the pressure-sensitive adhesive layer is post-cured by heating, heat treatment is performed in an oven at 100° C. for 3 hours with the separator films attached to both surfaces of the pressure-sensitive adhesive layer.
Among them, the gel fraction in the semi-cured state of the pressure-sensitive adhesive layer is preferably 10% by mass or more and less than 70% by mass, more preferably 12% by mass or more and less than 70% by mass, and 15 to 65% by mass. Is more preferable.
The gel fraction of the pressure-sensitive adhesive layer after post-curing is preferably 60 to 100% by mass, more preferably 65 to 100% by mass, and further preferably 70 to 100% by mass.
The gel fraction of the pressure-sensitive adhesive layer is a value measured by the following method. First, about 0.1 g of the adhesive sheet (adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and the mixture is shaken for 24 hours. Then, the contents of this sample bottle are filtered by a 150-mesh stainless steel wire net, and the residue on the wire net is dried at 100° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the gel fraction is calculated by the following formula 1.
Gel fraction (mass %)=(dry mass/adhesive sheet collection mass)×100...Equation 1

In the present specification, the “semi-cured state” is preferably the state after heat curing. Then, after that, it is preferable to perform "post-curing" by irradiating with active energy rays. That is, the “semi-cured state” is preferably a state after heat curing and a soft pressure-sensitive adhesive layer before irradiation with active energy rays. The "post-curing" is preferably a step of completely curing the pressure-sensitive adhesive layer with heat or active energy rays, and more preferably a step of completely curing the pressure-sensitive adhesive layer with active energy rays. 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.

When the pressure-sensitive adhesive layer is post-cured, the pressure-sensitive adhesive layer satisfies the following physical properties (1) to (3). That is, the pressure-sensitive adhesive layer having a gel fraction of 65 to 100 mass% upon irradiation with active energy rays satisfies the following physical properties (1) to (3).
Physical properties (1): Tensile storage elastic modulus E′ measured at 23° C. and frequency 1 Hz is 5.0×10 ⁶ Pa or more, and tensile storage elastic modulus E′ measured at 85° C. and frequency 1 Hz is 3. It is 0×10 ⁵ Pa or more.

When the pressure-sensitive adhesive layer is post-cured, the tensile storage elastic modulus E′ measured at 23° C. and a frequency of 1 Hz is preferably 1.0×10 ⁷ Pa or more, and 1.5×10 ⁷ Pa or more. Is more preferable. There is no particular upper limit to the tensile storage elastic modulus E′ measured at 23° C. and a frequency of 1 Hz when the pressure-sensitive adhesive layer is post-cured, and it can be set to 1.0×10 ⁹ Pa or less, for example.
When the adhesive layer is post-cured, the tensile storage elastic modulus E′ measured at 85° C. and a frequency of 1 Hz is preferably 4.0×10 ⁵ Pa or more, and 5.0×10 ⁵ Pa or more. Is more preferable. There is no particular upper limit to the tensile storage elastic modulus E′ measured at 85° C. and a frequency of 1 Hz when the pressure-sensitive adhesive layer is post-cured, and can be set to 1.0×10 ⁸ Pa or less, for example.

When the pressure-sensitive adhesive layer is post-cured, the pressure-sensitive adhesive sheet satisfies the following physical properties (2).
Physical property (2): The probe tack value measured at 23° C. and the following measurement conditions is 1.0 N/5 mmφ or less.
(Probe tack value measurement conditions)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 Mirror surface weight by polishing: 19.6±0.2g (made of brass)
Probe moving speed: 1.0 cm/sec Duel time: 1 sec

The probe tack value of the pressure-sensitive adhesive sheet measured at 23° C. under the above measurement conditions is more preferably 0.8 N/5 mmφ or less, further preferably 0.5 N/5 mmφ or less. The lower limit of the probe tack value of the pressure-sensitive adhesive sheet measured at 23° C. under the above measurement conditions is not particularly limited, but can be set to 0.01 N/5 mmφ or more, for example.

Furthermore, when the pressure-sensitive adhesive layer is post-cured, the pressure-sensitive adhesive sheet satisfies the following physical properties (3).
Physical property (3): The constant load peeling distance at 23° C. measured under the following measuring condition (a) is 20 mm or less, and the constant load peeling distance at 85° C. measured under the following measuring condition (b) is 100 mm or less. ..
(Measurement condition (a))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. In an environment of 23° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 300 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 30 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 23°C.
(Measurement condition (b))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. Under an environment of 85° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 100 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 10 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 85°C.

When performing the above measurement, first, a test piece for measurement is prepared by the following method. A triacetyl cellulose film (Fujitac TD60UL, thickness 60 μm, manufactured by FUJIFILM Corporation) is attached to one surface of the pressure-sensitive adhesive sheet using a hand roller to prepare a laminated film. This laminated film is cut into a width of 25 mm and a length of 100 mm, and then the other side of the adhesive sheet has a width of 25 mm and a length of 100 mm. Polycarbonate plate with coat layer: Mitsubishi Gas Chemical Co., Inc., Iupilon MR58, thickness 1 mm) is attached to the hard coat surface side using a 2 kg pressure roller. In this state, it is kept in an autoclave under the conditions of 40° C. and 5 atm for 30 minutes to be brought into close contact with the adherend. Two such test pieces are produced.
In the above measurement conditions, when post-curing is performed, ultraviolet rays are irradiated from the triacetyl cellulose film side of the test piece for measurement so that the integrated light amount becomes 3000 mJ/cm ² , 23° C., 50% relative humidity. Leave for 24 hours in the environment.

Regarding one set of test pieces, as shown in FIG. 2 under the environment of 23° C., the lengthwise end of the non-bonded region (width 25 mm, length 25 mm) of the laminated film composed of the adhesive sheet 1 and the triacetyl cellulose film 30. The weight 34 of 300 g is hung on the part, a load of 300 g is applied in the direction of 90° with respect to the plane of the adherend 32, and the state is left for 30 minutes. In the meantime, the length L (constant load peeling distance) of the portion where the laminated film is peeled off is measured (constant load peeling distance under measurement condition (a)).
For the other set of test pieces, after leaving them in the environment of 85° C. for 30 minutes, in the environment of 85° C., as shown in FIG. 2, the non-bonding area (width 25 mm, length 25 mm) of the laminated film in the longitudinal direction A 100 g weight 34 is hung at the end, a load of 100 g is applied in the direction of 90° to the plane of the adherend 32, and the state is left for another 10 minutes. During that time, the length L (constant load peeling distance) of the portion where the laminated film is peeled off is measured (constant load peeling distance under measurement condition (b)).

The constant load peeling distance at 23° C. measured under the measurement condition (a) is preferably 10 mm or less, and more preferably 5 mm or less. The constant load peeling distance at 23° C. measured under the measurement condition (a) may be 0 mm. Further, the constant load peeling distance at 85° C. measured under the measurement condition (b) is preferably 80 mm or less, and more preferably 70 mm or less. The constant load peel distance at 85° C. measured under the measurement condition (b) may be 0 mm.

In the state before the pressure-sensitive adhesive layer is post-cured, that is, when the pressure-sensitive adhesive layer is in the semi-cured state, the pressure-sensitive adhesive sheet preferably satisfies the following physical properties (4).
Physical properties (4): Shear storage elastic modulus G′ measured at 23° C. and frequency 1 Hz is 8.0×10 ⁵ Pa or less, and shear storage elastic modulus G′ measured at 85° C. and frequency 1 Hz is 1. It is 0×10 ⁵ Pa or less.
The shear storage modulus G′ measured at 23° C. and a frequency of 1 Hz when the pressure-sensitive adhesive layer is in a semi-cured state is more preferably 6.5×10 ⁵ Pa or less. When the pressure-sensitive adhesive layer is in a semi-cured state, the lower limit value of the shear storage elastic modulus G′ measured at 23° C. and a frequency of 1 Hz is not particularly limited, and can be 1.0×10 ³ Pa or more, for example.
The shear storage elastic modulus G′ measured at 85° C. and a frequency of 1 Hz when the pressure-sensitive adhesive layer is in a semi-cured state is more preferably 8.0×10 ⁴ Pa or less. When the pressure-sensitive adhesive layer is in a semi-cured state, the lower limit value of the shear storage elastic modulus G′ measured at 85° C. and a frequency of 1 Hz is not particularly limited, and can be 1.0×10 ³ Pa or more, for example.

When the pressure-sensitive adhesive layer is in a semi-cured state, the probe tack value measured under the conditions of 23° C. and the above-mentioned measurement is more preferably 0.8 N/5 mmφ or more, and more preferably 1.0 N/5 mmφ or more. preferable. When the pressure-sensitive adhesive layer is in a semi-cured state, the probe tack value measured at 23° C. under the above-mentioned measurement conditions is preferably 20.0 N/5 mmφ or less, and more preferably 15.0 N/5 mmφ or less. preferable.

The thickness of the pressure-sensitive adhesive layer can be appropriately set depending on the application and is not particularly limited, but is preferably 5 to 150 μm, more preferably 8 to 100 μm, and particularly preferably 10 to 80 μm. By setting the thickness of the pressure-sensitive adhesive layer within the above range, the pressure-sensitive adhesive can be prevented from sticking out and stickiness, so that the processability can be improved. Furthermore, when the thickness of the pressure-sensitive adhesive layer is within the above range, the double-sided pressure-sensitive adhesive sheet can be easily manufactured.

<Adhesive composition>
The above-mentioned pressure-sensitive adhesive layer is obtained by semi-curing the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition used in the present invention is a dual-curable pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition is a crosslinkable acrylic polymer, a crosslinker, a polyfunctional monomer having two or more reactive double bonds in the molecule, and a monofunctional monomer having one reactive double bond in the molecule. And preferably containing a polymerization initiator. Here, the polyfunctional monomer preferably has a bisphenol skeleton in one molecule.

(Crosslinkable acrylic polymer)
The crosslinkable acrylic polymer is not particularly limited as long as it has an acrylic monomer unit. For example, a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer having a crosslinkable functional group. It may contain the body unit (a2). The crosslinkable acrylic polymer is preferably one having transparency such that the visibility of the display device is not deteriorated. In addition, in the present specification and claims, the “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 a (meth)acrylic acid alkyl ester. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 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 (meth)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. These may be used alone or in combination of two or more.
Among the above-mentioned (meth)acrylic acid alkyl esters, at least one selected from methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferred 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 kind or two or more kinds 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 (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 a repeating unit 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 value of the above range, it has sufficient crosslinkability necessary for maintaining a semi-cured state, If the value is less than or equal to the upper limit value, it is easy to maintain the required tackiness.

The crosslinkable acrylic polymer contains a unit derived from an alkoxyalkyl group-containing (meth)acrylate, a unit derived from a hydroxy group-containing (meth)acrylate, and a unit derived from a methyl (meth)acrylate. May be.

The alkoxyalkyl group-containing (meth)acrylate is an alkoxyalkyl (meth)acrylate. As the alkoxyalkyl(meth)acrylate, for example, an alkoxyalkyl(meth)acrylate in which the alkoxy group has 1 to 12 carbon atoms and the alkylene group bonded to the alkoxy group has 1 to 18 carbon atoms is preferable. The alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and particularly preferably 1 or 2 carbon atoms. The alkylene group bonded to the alkoxy group preferably has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms. preferable.

Examples of such alkoxyalkyl (meth)acrylates include 2-methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate and the like can be mentioned. Among these, 2-methoxyethyl (meth)acrylate is particularly preferable. By using 2-methoxyethyl (meth)acrylate as the alkoxyalkyl (meth)acrylate, the pressure-sensitive adhesive layer in the semi-cured state can improve wettability with respect to the substrate while suppressing stickiness.

When the crosslinkable acrylic polymer contains units derived from the alkoxyalkyl group-containing (meth)acrylate, the content of the units derived from the alkoxyalkyl group-containing (meth)acrylate is based on the total weight of the crosslinkable acrylic polymer. On the other hand, it is preferably 50% by mass or more, more preferably 55% by mass or more, and further preferably 60% by mass or more. The content of the units derived from the alkoxyalkyl group-containing (meth)acrylate is preferably 90% by mass or less based on the total mass of the crosslinkable acrylic polymer. By setting the content of the unit derived from the alkoxyalkyl group-containing (meth)acrylate within the above range, the semi-cured pressure-sensitive adhesive layer can be easily adhered to the substrate, while the post-cured pressure-sensitive adhesive layer is adhered. The agent layer has high hardness, and high temperature durability and processability can be further enhanced.

Examples of the hydroxy group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth). Examples thereof include acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and polyalkylene glycol mono(meth)acrylate. Among them, at least one selected from 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate is preferably used.

When the crosslinkable acrylic polymer contains units derived from the hydroxy group-containing (meth)acrylate, the content of the units derived from the hydroxy group containing (meth)acrylate is based on the total mass of the crosslinkable acrylic polymer. It is preferably 5% by mass or more, and more preferably 7% by mass or more. The content of units derived from the hydroxy group-containing (meth)acrylate is preferably 35% by mass or less, and more preferably 30% by mass or less, based on the total mass of the crosslinkable acrylic polymer. .. By setting the content of the unit derived from the hydroxy group-containing (meth)acrylate within the above range, the adhesion to the adherend can be further enhanced.

The crosslinkable acrylic polymer may contain a unit derived from methyl (meth)acrylate. In this case, the content of the unit derived from methyl (meth)acrylate is preferably 5% by mass or more, and more preferably 7% by mass or more, based on the total mass of the crosslinkable acrylic polymer. Further, the content of the unit derived from methyl (meth)acrylate is preferably 35% by mass or less, and more preferably 30% by mass or less, based on the total mass of the crosslinkable acrylic polymer.

The crosslinkable acrylic polymer may further include units derived from a nitrogen-containing monomer. The nitrogen-containing monomer is a monomer containing a nitrogen element in one molecule. Examples of the nitrogen-containing monomer include dimethylacrylamide, diethylacrylamide, acryloylmorpholine, hydroxyethylacrylamide, methylolacrylamide, methoxymethylacrylamide, ethoxymethylacrylamide, dimethylaminoethylacrylamide, N-vinylcaprolactam, and N-vinyl-2-. Pyrrolidone, dimethylaminoethyl (meth)acrylate, N-vinylformamide and the like can be mentioned. Among them, the nitrogen-containing monomer is preferably at least one selected from acrylamide derivatives, amino group-containing monomers and nitrogen-containing heterocycle-containing monomers, and more preferably acrylamide derivatives. The acrylamide derivative is more preferably at least one selected from dimethylacrylamide, diethylacrylamide and acryloylmorpholine, and particularly preferably dimethylacrylamide. The crosslinkable acrylic polymer, by containing a unit derived from the nitrogen-containing monomer as described above, the semi-cured pressure-sensitive adhesive layer is easy to adhere to the substrate, while after post-curing The pressure-sensitive adhesive layer has a high hardness, and high temperature durability and processability can be further enhanced.

When the crosslinkable acrylic polymer contains units derived from the nitrogen-containing monomer, the content of the units derived from the nitrogen-containing monomer is 1% by mass or more based on the total mass of the crosslinkable acrylic polymer. It is preferable that the amount is 3% by mass or more. Further, the content of the units derived from the nitrogen-containing monomer is preferably 20% by mass or less based on the total mass of the crosslinkable acrylic polymer.

The crosslinkable acrylic polymer may have other monomer units, if necessary. Any other monomer may be used as long as it can be copolymerized with the above-mentioned acrylic monomer, and examples thereof include (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, and vinylpyridine. The content of the other monomer unit in the crosslinkable acrylic polymer is preferably 20% by mass or less, and more preferably 15% by mass or less.

<Weight average molecular weight of crosslinkable acrylic polymer>
The weight average molecular weight of the crosslinkable acrylic polymer is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,500,000. When the weight average molecular weight is within the above range, the semi-cured state of the pressure-sensitive adhesive sheet can be easily maintained, the hardness after post-curing can be easily obtained, and the workability 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 on a polystyrene basis. As the crosslinkable acrylic polymer, a commercially available one may be used, or one synthesized by a known method may be used.

(Crosslinking agent)
The pressure-sensitive adhesive composition contains a crosslinking agent. The cross-linking agent can be appropriately selected in consideration of the reactivity with the cross-linkable functional group of the cross-linkable acrylic polymer. For example, it can be selected from known crosslinking agents such as an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, a metal chelate compound and a butylated melamine compound. Among these, it is preferable to use an isocyanate compound or an epoxy compound because the hydroxy group-containing (meth)acrylate can be easily crosslinked. That is, the crosslinking agent is preferably at least one selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound, and more preferably a bifunctional or higher functional isocyanate compound.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like. Examples of commercially available products include tolylene diisocyanate compound (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), xylylene diisocyanate compound (Takenate D-110N, manufactured by Mitsui Chemicals, Inc.) and the like.

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected depending on the desired adhesiveness and the like, but is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the cross-linkable acrylic polymer, and 0 0.1 to 3 parts by mass is more preferable. By setting the content of the cross-linking agent within the above range, the processability can be further enhanced. As the cross-linking agent, one kind may be used alone or two or more kinds may be used in combination, and when two kinds or more are used in combination, the total mass is preferably within the above range.

(Polyfunctional monomer)
The pressure-sensitive adhesive composition contains a polyfunctional monomer having two or more reactive double bonds in the molecule, and the polyfunctional monomer has a bisphenol skeleton in one molecule. By using a polyfunctional monomer having a bisphenol skeleton in one molecule, the hardness of the pressure-sensitive adhesive layer after post-curing can be more effectively increased, and the workability of the pressure-sensitive adhesive sheet can be increased.

Examples of such a polyfunctional monomer include bisphenol A diglycidyl ether diacrylate, propoxylated bisphenol A diacrylate, and bisphenol F diglycidyl ether diacrylate.

The polyfunctional monomer has two or more reactive double bonds, and among them, the polyfunctional monomer preferably has two or more and less than five reactive double bonds, and preferably two. It is more preferable that the number is less than four.

A commercial item can be used as a polyfunctional monomer. Examples of commercially available products include Toa Gosei Co., Ltd., bifunctional monomer M211B (bisphenol A ethylene oxide modified diacrylate), Toagosei Co., Ltd., bifunctional monomer M08 (bisphenol F ethylene oxide modified diacrylate), Shin Nakamura Chemical Co., Ltd. , A bifunctional monomer A-BPP-3 (propoxylated bisphenol A diacrylate) and the like.

The content of the polyfunctional monomer is preferably 5 to 30 parts by mass and more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer. The polyfunctional monomers may be used alone or in combination of two or more, and when two or more are used in combination, the total mass is preferably within the above range. By setting the content of the polyfunctional monomer within the above range, the hardness of the pressure-sensitive adhesive layer after post-curing can be more effectively increased, and the workability of the pressure-sensitive adhesive sheet can be increased.

(Monofunctional monomer)
The pressure-sensitive adhesive composition contains a monofunctional monomer having one reactive double bond in the molecule.

Examples of the monofunctional monomer include isobornyl acrylate, isostearyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, benzyl methacrylate, N-acryloyloxyethyl hexahydrophthalimide, acrylamide, N,N-dimethylacrylamide, N. , N-diethylacrylamide, acryloylmorpholine, vinylpyrrolidone and the like. Among them, the monofunctional monomer is preferably an alkyl (meth)acrylate, preferably at least one selected from isobornyl acrylate and isostearyl acrylate, and more preferably isobornyl acrylate. preferable. Examples of commercially available monofunctional monomers include IBXA manufactured by Osaka Organic Chemical Industry, ISTA manufactured by Osaka Organic Chemical Industry, and the like.

The glass transition temperature (Tg) of the homopolymer when a monofunctional monomer is polymerized is preferably −20° C. or higher, more preferably 0° C. or higher, further preferably 50° C. or higher, It is more preferably 55° C. or higher, particularly preferably 60° C. or higher. Further, the glass transition temperature (Tg) of the homopolymer obtained by polymerizing the monofunctional monomer is preferably 180° C. or lower, and more preferably 150° C. or lower.

The content of the monofunctional monomer is preferably 1 to 30 parts by mass, and more preferably 2 to 30 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer. The above monofunctional monomers may be used alone or in combination of two or more, and when two or more are used in combination, the total mass is preferably within the above range.

Further, the total content of the monofunctional monomer and the polyfunctional monomer is preferably 6 to 50 parts by mass, and more preferably 10 to 45 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic polymer. It is preferably from 15 to 40 parts by mass, and further preferably. By setting the total content of the monofunctional monomer and the polyfunctional monomer within the above range, it is possible to obtain a pressure-sensitive adhesive sheet which is excellent in processability because the stickiness of the end surface is suppressed after post-curing. Further, by setting the total content of the monofunctional monomer and the polyfunctional monomer within the above range, the high temperature durability and processability of the pressure-sensitive adhesive sheet after post-curing can be more effectively enhanced.

(Polymerization initiator)
The pressure-sensitive adhesive composition contains a polymerization initiator. The polymerization initiator is preferably one that initiates the polymerization of the polyfunctional monomer and/or the monofunctional monomer by irradiation with active energy rays, and the polyfunctional monomer and the monofunctional monomer are activated by irradiation with active energy rays. More preferably, it initiates the polymerization of the body. As the polymerization initiator, 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 rays, visible rays, X-rays, and ion rays. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.

Examples of the polymerization initiator include acetophenone type initiators, benzoin ether type initiators, benzophenone type initiators, hydroxyalkylphenone type initiators, thioxanthone type initiators, amine type initiators, acylphosphine oxide type initiators and the like. To be
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 and methyl o-benzoylbenzoate.
Specific examples of the hydroxyalkylphenone initiator include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., commercially available as IRGACURE184).
Specific examples of the thioxanthone initiator include 2-isopropylthioxanthone and 2,4-dimethylthioxanthone.
Specific examples of the amine-based initiator include triethanolamine and ethyl 4-dimethylbenzoate.
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 the active energy ray at the time of post-curing, and the like. Specifically, it is preferably 0.05 to 10% by mass, and more preferably 0.1 to 5.0% by mass, based on the total mass of the monomers. When it is at least the above lower limit, the workability is excellent because the desired hardness can be adjusted by post-curing. When it is at most the above upper limit, the molecular weight after post-curing does not become small and the workability is 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 adhesive composition may contain a solvent. In this case, the solvent is used for improving 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, relative to 100 parts by mass of the crosslinkable acrylic polymer.
Further, the content of the solvent is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total mass of the pressure-sensitive adhesive composition. As the solvent, one type may be used alone, or two or more types may be used in combination. 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 effect of the present invention is not impaired. When the pressure-sensitive adhesive composition contains the plasticizer, the pressure-sensitive adhesive sheet can fill the step formed on the adherend and enhance the step followability. The plasticizer is preferably a non-functional acrylic polymer. As the non-functional acrylic polymer, a polymer composed only of an acrylic monomer unit having no functional group other than an acrylate group, or an acrylic monomer unit having no functional group other than an acrylate group and having no functional group A polymer including a non-acrylic monomer unit can be mentioned. Since the non-functional group acrylic polymer is not cross-linked, it is possible to enhance the step followability without affecting the tackiness.
Examples of the acrylic monomer unit having no functional group other than the acrylate group include non-crosslinkable alkyl (meth)acrylate. 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 stearin. Examples thereof include vinyl carboxylates such as vinyl acetate, vinyl cyclohexanecarboxylate, vinyl benzoate, and styrene.

(Other ingredients)
The pressure-sensitive adhesive composition may contain components other than the above components as long as the effects of the present invention are not impaired. Examples of other components include components known as additives for pressure-sensitive 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. Further, a dye or a pigment may be added for the purpose of coloring.
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. These antioxidants may be used alone or in combination of two or more.
As the metal corrosion inhibitor, a benzotriazole resin can be mentioned as a preferable example because of the compatibility of the pressure-sensitive adhesive and the high effect.
Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, coumarone indene resin, styrene resin, xylene resin, phenol resin, petroleum resin and the like.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (eg, a mercapto group-substituted alkoxy oligomer).
Examples of the ultraviolet absorber include benzotriazole compounds and benzophenone compounds. However, when ultraviolet rays are used as the active energy rays at the time of post-curing, it is preferable to add them in a range that does not hinder the polymerization reaction.

<Production method of adhesive sheet>
The method for producing a pressure-sensitive adhesive sheet of the present invention includes a step of applying the above-mentioned pressure-sensitive adhesive composition on a release sheet to form a coating film, and a step of heating the coating film to a semi-cured cured product. It is preferable. By heating the coating film, the reaction of the crosslinkable acrylic polymer and the crosslinking agent proceeds to form a semi-cured cured product (adhesive layer). That is, during heating, the polymerization reaction of the monomer with the polymerization initiator does not proceed in the coating film, or even if it progresses slightly, the adhesive layer contains a unit amount contained in the adhesive composition. At least a part of the body and the polymerization initiator are 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 carry out an aging treatment in which the pressure-sensitive adhesive sheet is allowed to stand at a constant temperature for a fixed period after the solvent is removed after coating. The aging treatment can be carried out, for example, by allowing it to stand at 23° C. for 7 days.

The semi-cured pressure-sensitive adhesive layer can be post-cured by irradiating with active energy rays after being attached to an adherend such as a base material. That is, the pressure-sensitive adhesive sheet of the present invention is a two-stage curable pressure-sensitive adhesive sheet, has a pressure-sensitive adhesive layer that is semi-cured only by heat before bonding, and after bonding, the pressure-sensitive adhesive layer is post-cured by active energy rays. To be done.

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 microgravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.

A known heating device such as a heating furnace or an infrared lamp can be used to heat 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 to bring the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet into contact with the surface of the adherend. In the method of using the pressure-sensitive adhesive sheet, it is preferable that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is bonded to the adherend when the pressure-sensitive adhesive layer is in a semi-cured state, and the pressure-sensitive adhesive layer is post-cured by irradiation with active energy rays.

<Use of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention is preferably used for optical members that require durability, especially for applications that require complicated punching after forming a laminated body.
The pressure-sensitive adhesive sheet of the present invention is preferably capable of suppressing the generation of bubbles even when it is attached to an adherend such as a base material, post-cured, and then exposed to a high-humidity heat environment. The pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive sheet used for application to a substrate, and more preferably a pressure-sensitive adhesive sheet used for application to a polycarbonate substrate. Examples of the polycarbonate substrate include PC-1151 manufactured by Teijin Chemicals Ltd. and the like.

The pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive sheet used for directly bonding to a base material, but may be used for indirectly bonding to a base material. For example, it may be attached to a multi-layer substrate including a polycarbonate substrate. 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 an acrylic type, a urethane type, a silicone type, a melamine type and an epoxy type, more preferably an acrylic type and a silicone type. The composition of the hard coat layer is more preferably an acrylic type from the viewpoint of workability and hardness.
As the multilayer base material including the polycarbonate base material, for example, MR-58 or IMR05 manufactured by Mitsubishi Gas Chemical Co., Inc. can be used. Here, the structure of MR-58 is HC (hard coat)/PMMA (polymethylmethacrylate)/PC (polycarbonate)/HC (hard coat). It is preferable that the MR-58 has a total thickness of 0.3 mm to 1.2 mm and one hard coat layer has a thickness of 0.0005 mm to 0.02 mm. The configuration 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 heat environment. .. Here, the polarizing plate includes a polarizer and a polarizer protective film, and the pressure-sensitive adhesive sheet of the present invention is preferably attached to the polarizer protective film. As the polarizer protective film, cycloolefin resin film, cellulose acetate resin film such as triacetyl cellulose and diacetyl cellulose, polyester resin film such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, polycarbonate resin film, acrylic Examples thereof include a resin resin film and a polypropylene resin film. In particular, when the polarizer protective film is a cellulose acetate-based resin film, the use of the pressure-sensitive adhesive sheet of the present invention exerts the effect of suppressing bubble generation.
In the present invention, generation of bubbles in the adherend of the pressure-sensitive adhesive sheet can be suppressed, and therefore, when the pressure-sensitive adhesive sheet is incorporated into a display device or the like, it is possible to prevent deterioration of visibility.

[Laminate]
The present invention also relates to a laminate having the above-mentioned pressure-sensitive adhesive sheet and an adherend. The laminate is a pressure-sensitive adhesive layer after post-curing, which is obtained by irradiating the pressure-sensitive adhesive layer of the above-mentioned pressure-sensitive adhesive sheet with active energy rays, and at least one surface side of the pressure-sensitive adhesive layer after post-curing. Equipped with. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the laminate is formed by post-curing by irradiating active energy rays in a state where two adherends are bonded with a semi-cured pressure-sensitive adhesive sheet. Is preferred. Here, 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.

FIG. 3 is a schematic view showing a cross section of an example of the laminate of the present invention. FIG. 3 is a cross-sectional view showing an example of the configuration of the laminate 20 in which the pressure-sensitive adhesive sheet 21 of the present invention is attached to the base material 22 and the optical member 24. As shown in FIG. 3, the pressure-sensitive adhesive sheet 21 of the present invention is preferably used for bonding to the base material 22, and is 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 laminated body include various constituent members in optical products such as a touch panel and an image display device, and an anti-scattering film attached to the cover lens of the outermost layer. As a component of the touch panel, for example, an ITO film provided with an ITO film on a transparent resin film, an ITO glass provided with an ITO film on the surface of a glass plate, a transparent conductive film obtained by coating a conductive polymer on a transparent resin film, A hard coat film, a fingerprint resistant film and the like can be mentioned. Examples of constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device.
Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

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 pressure-sensitive adhesive sheet of the present invention includes bonding of transparent optical films to each other inside a touch panel, bonding of transparent optical film and glass, bonding of transparent optical film of touch panel and liquid crystal panel, cover glass. And a transparent optical film, or a cover glass and a transparent optical film, and is useful when either member is a polycarbonate substrate. 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, or a cycloolefin polymer film can be used. A hard coat layer may be provided on the transparent optical film or the polycarbonate substrate.

FIG. 4 is a schematic view showing a cross section of another example of the laminated body of the present invention. As shown in FIG. 4, the adherend may have stepped portions (27a, 27b, 27c, 27d). In FIG. 4, the base material has step portions (27a, 27b), and the optical member has step portions (27c, 27d). The thickness of the step portions (27a, 27b, 27c, 27d) is usually 5 to 60 μm. As described above, the pressure-sensitive adhesive sheet 21 of the present invention can be attached to a member having a step portion, and can follow the unevenness generated from the step portion.

[Method for manufacturing laminated body]
The method for producing a laminate includes a step of sticking the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet described above to an adherend in a semi-cured state, and then irradiating an active energy ray to post-cure the pressure-sensitive adhesive layer. Prior to irradiation with active energy rays, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state, so that the initial adhesion to the substrate is good. In this way, after the pressure-sensitive adhesive sheet is attached to the adherend, the adhesive layer is post-cured with active energy rays, whereby the cohesive force of the pressure-sensitive adhesive layer is increased and the adhesiveness to the adherend is improved. In addition, the post-cured pressure-sensitive adhesive layer can prevent the base material from being deformed or distorted.

Examples of active energy rays include ultraviolet rays, electron rays, visible rays, X rays, and ion rays, which can be appropriately selected according to the polymerization initiator contained in the pressure-sensitive adhesive layer. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.
As the ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or 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-Walt type, Bande-Craft type, resonance transformer type, insulating core transformer type, linear type, dynamitron type, high frequency type, etc. 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.

When the pressure-sensitive adhesive sheet is attached to the base material and the optical member, the active energy ray can be irradiated from either the base material side or the optical member side, but it is preferably irradiated from the base material side.

The features of the present invention will be described more specifically below with reference to Examples and Comparative Examples. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following specific examples.

[Example 1]
<Synthesis of crosslinkable acrylic polymer>
The crosslinkable acrylic polymer was made by solution polymerization in ethyl acetate. 2-methoxyethyl acrylate monomer (MEA), 2-hydroxyethyl acrylate monomer (2HEA), methyl methacrylate (MMA), dimethyl acrylamide (DMAA) and butyl acrylate (BA) in a mass ratio of 70:10:10:5:5. AIBN (azobisisobutyronitrile) was dissolved in the solution as a radical polymerization initiator. The solution was heated to 60° C. and subjected to random copolymerization to obtain a crosslinkable acrylic polymer A. The solution viscosity of the 35 mass% solution of the crosslinkable acrylic polymer A at 23° C. was 2000 mPa·s.

With respect to 100 parts by mass of the crosslinkable acrylic polymer A, 0.2 parts by mass of a xylylene diisocyanate compound (Takenate D-110N manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, and bisphenol A ethylene oxide as a polyfunctional monomer. Polymerization of 15 parts by mass of modified diacrylate (Aronix M211B manufactured by Toagosei Co., Ltd.) and 15 parts by mass of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., IBXA, Tg=97° C.) as a monofunctional monomer. 0.3 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., IRGACURE 184) was added as an initiator, and ethyl acetate was added as a solvent so that the solid content concentration was 40% by mass. An adhesive composition was obtained.

The above-mentioned pressure-sensitive adhesive composition was applied onto a first release sheet (heavy separator film, Teijin DuPont Films 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 25 μm. Then, it was dried at 100° C. for 3 minutes with a hot air dryer to remove the solvent and form a pressure-sensitive adhesive sheet having a semi-cured pressure-sensitive adhesive layer.
A second release sheet (light separator film, manufactured by Teijin DuPont Films Co., Ltd.), which has been subjected to a release treatment having a higher releasability than the first release sheet, is attached to one surface of this pressure-sensitive adhesive sheet, and an adhesive sheet with a release sheet is attached. A pressure-sensitive adhesive sheet of Example 1 which is a sheet was obtained.

[Example 2]
In <Synthesis of crosslinkable acrylic polymer> of Example 1, 2-hydroxyethyl acrylate was changed to 4-hydroxybutyl acrylate (4HBA) to obtain crosslinkable acrylic polymer B. The solution viscosity of the 35% by mass solution of the crosslinkable acrylic polymer B at 23° C. was 2300 mPa·s. 0.2 parts by mass of a xylylene diisocyanate compound (Takenate D-110N manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, and 100 parts by mass of a crosslinkable acrylic polymer B, and bisphenol A ethylene oxide as a polyfunctional monomer. 20 parts by mass of modified diacrylate (Aronix M211B manufactured by Toagosei Co., Ltd.), 20 parts by mass of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., IBXA, Tg=97° C.) as a monofunctional monomer are polymerized. 0.5 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE184, manufactured by BASF Japan Ltd.) was added as an initiator, and ethyl acetate was added as a solvent so that the solid content concentration was 40% by mass. An adhesive composition was obtained.
Using this pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1.

[Example 3]
In <Synthesis of crosslinkable acrylic polymer> of Example 1, 2-methoxyethyl acrylate monomer (MEA), 2-hydroxyethyl acrylate monomer (2HEA), methyl methacrylate (MMA), dimethyl acrylamide (DMAA) and butyl acrylate ( The mass ratio of (BA) was changed from 70:10:10:5:5 to 80:7:7:5:1 to obtain a crosslinkable acrylic polymer C. The solution viscosity of the 35 mass% solution of the crosslinkable acrylic polymer C at 23° C. was 2100 mPa·s. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the amount of the crosslinking agent added was 1.0 part by mass relative to 100 parts by mass of the crosslinkable acrylic polymer C.

[Example 4]
In <Synthesis of crosslinkable acrylic polymer> of Example 3, 2-hydroxyethyl acrylate was changed to 4-hydroxybutyl acrylate (4HBA) to obtain crosslinkable acrylic polymer D. The solution viscosity of this 35 mass% solution of the crosslinkable acrylic polymer D at 23°C was 2400 mPa·s. The amount of the crosslinking agent added to 100 parts by weight of the crosslinkable acrylic polymer D is 0.2 parts by weight, the addition amount of the polyfunctional monomer is 20 parts by weight, the addition amount of the monofunctional monomer is 20 parts by weight, and the polymerization is initiated. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 3 except that the amount of the agent added was changed to 0.5 part by mass.

[Example 5]
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the monofunctional monomer of Example 1 was changed from IBXA to ISTA manufactured by Osaka Organic Chemical Industry.

[Comparative Example 1]
The crosslinkable acrylic polymer was made by solution polymerization in ethyl acetate. 2-Hydroxyethyl acrylate monomer (2HEA), dimethyl acrylamide (DMAA) and butyl acrylate (BA) were mixed in a mass ratio of 5:20:75, and AIBN (azobisisobutyronitrile) was used as a radical polymerization initiator. ) Was dissolved in the solution. The solution was heated to 60° C. and subjected to random copolymerization to obtain a crosslinkable acrylic polymer E. The solution viscosity of the 35 mass% solution of the crosslinkable acrylic polymer E at 23° C. was 3500 mPa·s.

To 100 parts by mass of the crosslinkable acrylic polymer E, 0.2 parts by mass of a xylylene diisocyanate compound (Takenate D-110N manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, and trimethylolpropane propylene as a polyfunctional monomer. 30 parts by mass of oxide modified triacrylate (Toagosei Co., Ltd., Aronix M321) and 5 parts by mass of isostearyl acrylate (ISTA, Tg=-18°C, manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a monofunctional monomer. Parts, 0.3 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE184, manufactured by BASF Japan Ltd.) as a polymerization initiator, and ethyl acetate as a solvent so that the solid content concentration becomes 40% by mass. An adhesive composition was obtained by adding.
Using this pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1.

[Comparative example 2]
A pressure-sensitive adhesive composition of Comparative Example 2 and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the polyfunctional monomer, the monofunctional monomer and the polymerization initiator were not used.

[Comparative Example 3]
In <Synthesis of crosslinkable acrylic polymer> of Example 1, 2-methoxyethyl acrylate monomer (MEA), 2-hydroxyethyl acrylate monomer (2HEA), methyl methacrylate (MMA), dimethyl acrylamide (DMAA) and butyl acrylate ( The mass ratio of (BA) was changed from 70:10:10:5:5 to 0:10:10:5:75 to obtain a crosslinkable acrylic polymer F. The solution viscosity of this 35 mass% solution of the crosslinkable acrylic polymer F at 23°C was 1900 mPa·s. Otherwise in the same manner as in Example 1, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained.

[Comparative Example 4]
The polyfunctional monomer of Example 1 was changed from bisphenol A ethylene oxide modified diacrylate (Toagosei Co., Ltd., Aronix M211B) to trimethylolpropane propylene oxide modified triacrylate (Toagosei Co., Ltd., M321). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except for the above.

[Measurement and evaluation]
<Tensile storage elastic modulus E'and shear storage elastic modulus G'>
The pressure-sensitive adhesive sheets were overlapped so that the pressure-sensitive adhesive layer had a thickness of 200 μm to prepare a semi-cured measurement sample.
A pressure-sensitive adhesive sheet is laminated so that the pressure-sensitive adhesive layer has a thickness of 200 μm, and ultraviolet rays are radiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light amount becomes 3000 mJ/cm ^2, and a measurement sample after post-curing Was produced.
For the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of each measurement sample, a dynamic viscoelasticity device Rheogel-E4000 (manufactured by UBM Co., Ltd.) was used to determine the tensile storage elastic modulus E′ in the solid tensile mode and the shear storage elastic modulus G′. Measured the tensile storage elastic modulus E′ and the shear storage elastic modulus G′ of the pressure-sensitive adhesive layer in the temperature range from 0° C. to 150° C. under the conditions of a frequency of 1 Hz and a strain of 0.1% using solid shear mode. ..

<Probe tack value>
The second release sheet, which is a light separator film of the pressure-sensitive adhesive sheet, was peeled off and attached to a PET film to prepare a measurement sample in a semi-cured state.
The second release sheet, which is a light separator film of another pressure-sensitive adhesive sheet, was peeled off and attached to a PET film. Next, ultraviolet rays were radiated from the side of the first release sheet, which was a heavy separator film, so that the integrated light amount was 3000 mJ/cm ^2, and a post-curing measurement sample was prepared.
Each measurement sample was cut into 3 cm×3 cm, and measured with a probe tack tester under the following conditions. The measurement temperature was 23°C.
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 Mirror surface weight by polishing: 19.6 g (made of brass)
Probe moving speed: 1.0 cm/sec Duel time: 1 sec

<Constant load peel distance>
The light release separator which is the second release sheet was peeled off, and instead of the peeled off separator, a triacetyl cellulose film (Fuji Film Co., Fujitac TD60UL thickness 60 μm) was laminated using a hand roller to prepare a laminated film. .. This laminated film was cut into a size having a width of 25 mm and a length of 100 mm, and the first release sheet was peeled off. Then, the exposed area of 25 mm in width and 100 mm in length of the adhesive surface is covered with a region of 25 mm in width and 75 mm in length on the hard coat surface side of the adherend (polycarbonate plate with hard coat layer: Mitsubishi Gas Chemical Co., Inc., Iupilon MR58 thickness 1 mm) Was attached using a 2 kg pressure roller. In this state, it was kept in an autoclave under the conditions of 40° C. and 5 atm for 30 minutes and brought into close contact with the PC plate, and then irradiated with ultraviolet rays from the triacetyl cellulose film side so that the integrated light amount was 3000 mJ/cm ² , A test piece was prepared by leaving it for 24 hours in an environment of 23° C. and a relative humidity of 50%. Two of the above test pieces were produced.
Regarding one of the test pieces, the length of the non-bonding region (width 25 mm, length 25 mm) of the laminated film composed of the adhesive sheet 1 and the triacetyl cellulose film 30 as shown in FIG. 2 under the environment of 23° C. The weight 34 of 300 g was hung at the end of the direction, a load of 300 g was applied in the direction of 90° to the plane of the adherend 32, and the state was left for 30 minutes. During that time, the length L (constant load peeling distance) of the portion where the laminated film was peeled off was measured. The other test piece was left in an environment of 85°C for 30 minutes, and then, in an environment of 85°C, as shown in Fig. 2, a non-bonding region (width 25 mm, length 25 mm) of the laminated film in the longitudinal direction. A weight 34 of 100 g was hung on the surface of the adherend 32, a load of 100 g was applied in the direction of 90° with respect to the plane of the adherend 32, and the state was left for another 10 minutes. During that time, the length L (constant load peeling distance) of the portion where the laminated film was peeled off was measured.

<Gel fraction>
The pressure-sensitive adhesive layer was cut to have a size of 100 mm×60 mm to prepare a semi-cured measurement sample.
The pressure-sensitive adhesive layer was cut to have a size of 100 mm×60 mm, and ultraviolet rays were irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light amount was 3000 mJ/cm ^2, and the measurement sample after post-curing was used. It was made.
About 0.1 g of the 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 with a 150-mesh stainless steel wire net, and the residue on the wire net was dried at 100° C. for 1 hour to measure the dry mass (g). The gel fraction was calculated from the obtained dry mass by the following formula 1.
Gel fraction (mass %)=(dry mass/adhesive sheet collection mass)×100...Equation 1

<End face stickiness>
Fifty sheets of A4 size adhesive sheets, which were irradiated with ultraviolet rays from the side of the first release sheet, which is a heavy separator film, so that the integrated light amount was 3000 mJ/cm ² , were overlapped to prepare a post-curing cutting sample.
The guillotine blade when the adhesive sheet used as a cutting sample after post-curing was cut with a guillotine cutting machine, and the end surface which was the cutting surface of the adhesive sheet was visually determined.
There is no protrusion of the adhesive from the cut surface of the pressure-sensitive adhesive sheet, and there is no stickiness on the guillotine blade and the cut surface, which is good.
The adhesive does not easily stick out from the cut surface of the pressure-sensitive adhesive sheet, and the stickiness of the guillotine blade and the cut surface of the cut surface is a practical problem.

<Workability>
First, the second release sheet, which is a light separator film for the pressure-sensitive adhesive layer, was peeled off and attached 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 board. A sample having a composition of PET/adhesive layer/PC was autoclaved (40° C., 0.5 MPa, 30 min), and then ultraviolet rays were irradiated from the PET film side so that the accumulated light amount became 3000 mJ/cm ^2, and a test sample Got Next, the end portion of the test sample was cut using a guillotine cutting machine, and the cut end portion was rubbed by peeling the PET film from the PC plate side by hand. The peeling distance at that time was measured.
Peeling distance is less than 0.05mm...◎
Peeling distance is 0.05 mm or more and less than 0.1 mm... 〇 Peeling distance is 0.1 mm or more... ×

<High temperature durability>
First, the second release sheet, which is a light separator film for the pressure-sensitive adhesive layer, was peeled off and laminated on a triacetyl cellulose film (Fujitac TD60UL, thickness 60 μm, manufactured by Fuji Film Co., Ltd.).
Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC board. A sample having a structure of triacetyl cellulose film/adhesive layer/PC was autoclaved (40° C., 0.5 MPa, 30 min), and then irradiated with ultraviolet rays from the PET film side so that the accumulated light amount was 3000 mJ/cm ^2. A test sample having a size of 100 mm×200 mm was obtained. Next, the test sample was placed in a dry environment at 105° C., and after 240 hours, the occurrence of floating and peeling was observed.
No floating or peeling is observed...○
Floating and/or peeling of 1.0 mm or more is observed... ×

MEA: 2-methoxyethyl acrylate 2HEA: 2-hydroxyethyl acrylate 4HBA: 4-hydroxybutyl acrylate MMA: methyl methacrylate DMAA: dimethylacrylamide BA: butyl acrylate M211B: bisphenol A ethylene oxide modified diacrylate M321: trimethylolpropane propylene oxide modified Triacrylate IBXA: Isobornyl acrylate ISTA: Isostearyl acrylate

From Table 1 above, it was found that the pressure-sensitive adhesive sheets of Examples had excellent high temperature durability. In addition, the pressure-sensitive adhesive sheets of Examples had no stickiness on the end faces and had good processability.

On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 4 have a post-curing tensile storage elastic modulus E′ at 23° C. of less than 5.0×10 ⁶ Pa and a constant load peel distance of 100 mm under the measurement condition (b). High temperature durability was inferior because it exceeded. Further, also in Comparative Example 2, since the value of the tensile storage elastic modulus E′ and the constant load peeling distance did not satisfy the predetermined conditions, the high temperature durability was poor, the end face was sticky, and the workability was poor. In Comparative Example 3 as well, the tensile storage elastic modulus E′ did not satisfy the predetermined condition, and therefore the high temperature durability was poor.

DESCRIPTION OF SYMBOLS 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 member 27a, 27b, 27c, 27d Step part 30 Triacetyl cellulose film 32 Adherent 34 Weight L Constant load separation distance

Claims (12)

A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state,
The pressure-sensitive adhesive composition comprises a crosslinkable acrylic polymer, a crosslinker, a polyfunctional monomer having two or more reactive double bonds in the molecule, and a monofunctional monofunctional monomer having one reactive double bond in the molecule. Contains a polymer and a polymerization initiator,
The polyfunctional monomer has a bisphenol skeleton in one molecule,
The crosslinkable acrylic polymer is derived from a unit derived from an alkoxyalkyl group-containing (meth)acrylate, a unit derived from a hydroxy group-containing (meth)acrylate, a unit derived from methyl (meth)acrylate and a nitrogen-containing monomer. Have units to
The content of the cross-linking agent is 0.01 to 5 parts by mass, the content of the polyfunctional monomer is 5 to 30 parts by mass, and the monofunctional monofunctional monomer is 100 parts by mass of the crosslinkable acrylic polymer. The content of the monomer is 1 to 30 parts by mass,
A pressure-sensitive adhesive sheet satisfying the following physical properties (1) to (3) when the pressure-sensitive adhesive layer is post-cured by irradiating the pressure-sensitive adhesive layer with active energy rays so that the integrated light amount becomes 3000 mJ/cm ² .
Physical properties (1): Tensile storage elastic modulus E′ measured at 23° C. and frequency 1 Hz is 1.0×10 ⁷ Pa or more, and tensile storage elastic modulus E′ measured at 85° C. and frequency 1 Hz is 4. 0×10 ⁵ Pa or more;
Physical properties (2): The probe tack value measured under the following measurement conditions at 23° C. is 0.5 N/5 mmφ or less;
(Probe tack value measurement conditions)
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 Mirror surface weight by polishing: 19.6±0.2g (made of brass)
Probe moving speed: 1.0 cm/sec Duel time: 1 sec Physical properties (3): The constant load peeling distance at 23° C. measured under the following measurement condition (a) is 5 mm or less, and under the measurement condition (b) below. The measured constant load peel distance at 85° C. is 70 mm or less:
(Measurement condition (a))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. In an environment of 23° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 300 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 30 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 23° C.;
(Measurement condition (b))
An area having a width of 25 mm and a length of 75 mm on the adhesive surface of an adhesive sheet having a width of 25 mm and a length of 100 mm is attached to an adherend and post-cured. Under an environment of 85° C., the adherend is horizontally fixed so that the non-bonding region of the pressure-sensitive adhesive sheet hangs downward. A load of 100 g is applied to the lengthwise end portion of the non-bonded region of the pressure-sensitive adhesive sheet for 10 minutes, and the distance at which the bonded region of the pressure-sensitive adhesive sheet is peeled from the adherend is measured as a constant load peel distance at 85°C. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer satisfies the following physical properties (4) in a semi-cured state:
Physical properties (4): Shear storage elastic modulus G′ measured at 23° C. and frequency 1 Hz is 8.0×10 ⁵ Pa or less, and shear storage elastic modulus G′ measured at 85° C. and frequency 1 Hz is 1. It is 0×10 ⁵ Pa or less. The pressure-sensitive adhesive sheet according to claim 1 or 2 gel fraction after post curing is 65 to 100 wt% when the pressure-sensitive adhesive layer is post-cured. The gel fraction in the semi-cured state of the pressure-sensitive adhesive layer is 10% by mass or more and less than 70% by mass, and
Gel fraction after post-curing if the adhesive layer is post-cured, pressure-sensitive adhesive sheet according to any one of claims 1 to 3 comprising greater 10 wt% or more than the gel fraction of a semi-cured state .. The pressure-sensitive adhesive sheet according to claim 1 , wherein the cross-linking agent is a difunctional or higher functional isocyanate compound. The total content of the monofunctional monomer polyfunctional monomer according to any one of claims 1 to 5, 6 to 50 parts by mass with respect to the cross-linkable acrylic polymer 100 parts by weight Adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1 , wherein the monofunctional monomer is an alkyl (meth)acrylate. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7 , wherein the polymerization initiator is one that initiates polymerization of the polyfunctional monomer and/or the monofunctional monomer by irradiation with active energy rays. Release-sheet laminated adhesive sheet release force to both surfaces of the adhesive sheet comprises a different pair release sheet together according to any one of claims 1-8. Polyethylene terephthalate film on at least one surface of the pressure-sensitive adhesive sheet according to any one of claims 1-8, at least one transparent film selected acrylic film, polycarbonate film, triacetyl cellulose film and cycloolefin polymer film A pressure-sensitive adhesive sheet with a transparent film. At least a post-curing pressure-sensitive adhesive layer obtained by post-curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 8 by irradiating with active energy rays, and at least the post-curing pressure-sensitive adhesive layer. A laminated body having an adherend on one surface side. 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, and then the active energy ray is irradiated to post-cure the pressure-sensitive adhesive layer. A method for manufacturing a laminated body including a step.

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