KR102171464B1 - Double-sided adhesive sheet and laminate - Google Patents

Abstract

An object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet having both step followability and outgassing resistance. The present invention relates to a substrate layer having a light transmittance of 50% or more with a wavelength of 370 nm, a first adhesive layer formed on one side of the substrate layer and curable after bonding, and a thickness of 5 μm or more and 75 It relates to a double-sided pressure-sensitive adhesive sheet having a second pressure-sensitive adhesive layer of µm or less.

Description

Double-sided adhesive sheet and laminate

The present invention relates to a double-sided adhesive sheet and a laminate.

In recent years, in various fields, an input device used in combination with a display device such as a liquid crystal display (LCD) or a display device such as a touch panel has been widely used. In the manufacture of these display devices and input devices, a transparent double-sided pressure-sensitive adhesive sheet is used for bonding optical members. For example, a double-sided pressure-sensitive adhesive sheet is widely used in order to bond two members, such as a cover glass, a touch panel and a display device, and a conductive member having a transparent electrode film such as ITO (Indium Tin Oxide) formed on a transparent support.

In portable telephone terminal devices such as smartphones, frame printing is performed in order to conceal electric circuits and the like inside the device. In this case, a decorative layer is often formed on the periphery of the back surface of the cover panel, and the pressure-sensitive adhesive layer adhered to the back surface of the cover panel is required to have a property capable of following the level of the decorative layer. In addition, when the cover panel is made of resin, the pressure-sensitive adhesive layer adhered to the back side of the cover panel needs to have adhesive force or cohesive force capable of countering the gas pressure of outgas generated from the resin panel. Thus, the pressure-sensitive adhesive layer may require both step followability and outgassing resistance, and a post-curing type pressure-sensitive adhesive layer by ultraviolet irradiation has been proposed as a means to achieve these problems (for example, Patent Document 1, etc. ).

Further, Patent Literature 2 discloses a double-sided pressure-sensitive adhesive sheet provided with a transparent water vapor barrier layer between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. Here, it is considered to provide a pressure-sensitive adhesive sheet suitable for bonding a glass plate by setting the storage modulus of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer into a predetermined range.

International Publication No. 2012/032995 Japanese Patent No. 3878386

In the case of using the ultraviolet post-curing pressure-sensitive adhesive layer as described in Patent Document 1, the bonding use is limited to bonding of an adherend that transmits ultraviolet rays. For example, in the case of using an ultraviolet post-curing type pressure-sensitive adhesive layer as described in Patent Document 1, both of the adherends formed on both sides of the pressure-sensitive adhesive sheet need to transmit ultraviolet light, and the application of the bonding has been limited.

In addition, in the pressure-sensitive adhesive sheet as described in Patent Document 2, it has become clear from the investigation of the present inventors that there may be cases where the level difference followability is insufficient and the outgassing resistance is insufficient.

Accordingly, the present inventors provide a double-sided pressure-sensitive adhesive sheet that can be applied to the bonding of adherends that do not transmit ultraviolet rays in order to solve the problems of the prior art, and has both step-following properties and outgassing resistance. For the purpose of this, the review was conducted.

As a result of intensive examination in order to solve the above problems, the present inventors improved the ultraviolet transmittance of the substrate layer in a double-sided adhesive sheet formed by laminating a first adhesive layer, a substrate layer, and a second adhesive layer in this order, In addition, it was found that by laminating the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer having predetermined physical properties through a substrate layer, a double-sided pressure-sensitive adhesive sheet having both properties of step followability and outgassing resistance can be obtained. The inventors of the present invention have found that such a double-sided pressure-sensitive adhesive sheet is applicable to bonding of adherends that do not transmit ultraviolet rays, and the present invention has been completed.

Specifically, the present invention has the following configuration.

[1] A base layer having a light transmittance of 50% or more with a wavelength of 370 nm, a first adhesive layer formed on one side of the base layer and curable after bonding, and a thickness of 5 μm or more, formed on the other side of the base layer, and 75 A double-sided pressure-sensitive adhesive sheet having a second pressure-sensitive adhesive layer of µm or less.

[2] The double-sided pressure-sensitive adhesive sheet according to [1], wherein the first pressure-sensitive adhesive layer is an adhesive layer having active energy ray curing ability.

[3] The double-sided pressure-sensitive adhesive sheet according to any one of [1] or [2], wherein the thickness of the first pressure-sensitive adhesive layer is 50 µm or more and 250 µm or less.

[4] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the first pressure-sensitive adhesive layer is bonded to a decorative base layer having a decorative layer on a part of one surface.

[5] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the second pressure-sensitive adhesive layer is bonded to a display device.

[6] A laminate comprising the double-sided adhesive sheet according to any one of [1] to [5], a decorative base layer laminated on a first adhesive layer, and a display device laminated on a second adhesive layer, The decorative base layer has a decorative layer on a part of one surface, and the surface having the decorative layer and the first adhesive layer are bonded to each other.

[7] The laminate according to [6], which further has a third adhesive layer and a surface cover layer, has a third adhesive layer on the decorative base layer, and has a surface cover layer on the third adhesive layer.

[8] The first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet according to any one of [1] to [5] is brought into contact with the surface on the side of the decorative layer of the decorative base layer having the decorative layer on a part of one surface, and in that state, the second A method for manufacturing a laminate comprising a step of completely curing the first pressure-sensitive adhesive layer by irradiating an active energy ray from the side of the pressure-sensitive adhesive layer, and a step of attaching a display device to the second pressure-sensitive adhesive layer.

Advantageous Effects of Invention According to the present invention, a double-sided pressure-sensitive adhesive sheet having both properties of step followability and outgassing resistance can be obtained. The double-sided adhesive sheet of the present invention is also useful for bonding adherends that do not transmit ultraviolet rays.

1 is a schematic cross-sectional view illustrating an aspect of the double-sided pressure-sensitive adhesive sheet of the present invention.
Fig. 2 is a schematic cross-sectional view illustrating the configuration of a laminate formed by bonding adherends using the double-sided pressure-sensitive adhesive sheet of the present invention.
Fig. 3 is a schematic cross-sectional view illustrating the configuration of a laminate formed by bonding adherends using the double-sided pressure-sensitive adhesive sheet of the present invention.

In the following, the present invention will be described in detail. The description of the constitutional requirements described below is made based on representative embodiments and specific examples, but the present invention is not limited to these embodiments.

(Double-sided adhesive sheet)

The present invention relates to a substrate layer having a light transmittance of 50% or more with a wavelength of 370 nm, a first adhesive layer formed on one side of the substrate layer and curable after bonding, and a thickness of 5 μm or more and 75 It relates to a double-sided pressure-sensitive adhesive sheet having a second pressure-sensitive adhesive layer of µm or less.

Since the double-sided pressure-sensitive adhesive sheet of the present invention has the above-described configuration, it has both properties of step followability and outgassing resistance. In the double-sided pressure-sensitive adhesive sheet of the present invention, the first pressure-sensitive adhesive layer is a curable pressure-sensitive adhesive layer after bonding to an adherend, and exhibits a flexible semi-cured state before bonding. In this state, since the first pressure-sensitive adhesive layer side is bonded to the adherend side having the uneven structure, it easily follows the step of the uneven portion. Thereafter, by irradiating with active energy rays from the side of the second pressure-sensitive adhesive layer to perform post-curing (main curing), the first pressure-sensitive adhesive layer becomes a completely cured state, firmly adheres to the adherend, and has excellent outgassing resistance. Can be demonstrated. In addition, in the present invention, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are laminated through a substrate layer, and by having such a configuration, even after the first pressure-sensitive adhesive layer is completely cured, the flexible second pressure-sensitive adhesive layer provides good for adherends. It can exhibit wettability (adhesion).

In addition, the "semi-cured state" in this specification refers to a state in which a part of the pressure-sensitive adhesive layer is cured by heat or active energy rays before bonding to an adherend, and refers to a flexible state before post-curing (main curing). In addition, the "semi-cured state" refers to a state in which dynamic viscoelasticity becomes 1.5 times or more after post-curing (main curing). The dynamic viscoelasticity is preferably 1.5 times or more and 1000 times or less, and more preferably 2 times or more and 100 times or less. The dynamic viscoelasticity of the pressure-sensitive adhesive layer in the semi-cured state in the present invention is preferably 1.0×10 ⁶ Pa or less, more preferably 8.0×10 ⁵ Pa or less, and particularly preferably 5.0×10 ⁵ Pa or less. The "completely cured (main cured) state" refers to a state in which the adhesive layer in a semi-cured state is irradiated with active energy rays to further cure the adhesive layer.

1 is a schematic cross-sectional view illustrating an aspect of the double-sided pressure-sensitive adhesive sheet of the present invention. As shown in FIG. 1, the double-sided adhesive sheet 100 has a base layer 10. In addition, the double-sided adhesive sheet 100 has a first adhesive layer 12 on one side of the base layer 10 and a second adhesive layer 14 on the other side of the base layer 10. The first adhesive layer 12 has a property capable of curing after being bonded to an adherend, and the thickness of the second adhesive layer 14 is 5 μm or more and 75 μm or less.

The total thickness of the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 50 µm or more, more preferably 100 µm or more, and even more preferably 150 µm or more. Moreover, it is preferable that it is 1 mm or less, and, as for the total thickness of a double-sided adhesive sheet, it is more preferable that it is 0.5 mm or less.

The double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding of adherends having steps. In this case, the first pressure-sensitive adhesive layer is bonded to the surface of the adherend having a step. As an adherend having a step, for example, a decorative base layer having a decorative layer on a part of one surface thereof may be mentioned, and the first pressure-sensitive adhesive layer is bonded to the side of the decorative base layer on the side on which the decorative layer is formed. Since the first pressure-sensitive adhesive layer is excellent in step-following property, the double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding of adherends having such a step.

The decorative base layer having a decorative layer may be a resin base layer. Since the double-sided pressure-sensitive adhesive sheet of the present invention is excellent in outgassing resistance, even when the decorative base layer is a resin layer, generation of bubbles after bonding can be suppressed.

In the double-sided pressure-sensitive adhesive sheet of the present invention, it is preferable that the second pressure-sensitive adhesive layer is bonded to the optical member. Examples of the optical member include a display device, and the display device is a liquid crystal display device (liquid crystal display panel), a plasma display device (plasma display panel), an organic electroluminescence display device (organic EL panel), and the like. It is desirable.

(Substrate layer)

The double-sided adhesive sheet of the present invention includes a substrate layer. The base material layer is formed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, and serves to hinder the transfer of the monomer component of the pressure-sensitive adhesive from the first pressure-sensitive adhesive layer to the second pressure-sensitive adhesive layer. By forming the base layer in this way, it is possible to improve the level difference followability and outgassing resistance of the double-sided adhesive sheet.

The base layer contains resin. Resins included in the base layer include, for example, polyolefin resins such as polyethylene resin and polypropylene resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyester resin such as polybutylene terephthalate resin, polyvinyl chloride resin, And various synthetic resins such as polystyrene resin, polyurethane resin, polycarbonate resin, polyamide resin, polyimide resin, fluorine resin, and cycloolefin polymer resin. Among them, at least one selected from polyethylene terephthalate resin (PET resin) and cycloolefin polymer resin (COP resin) is preferably used, and polyethylene terephthalate resin (PET resin) is particularly preferably used.

The light transmittance of the substrate layer at a wavelength of 370 nm may be 50% or more, preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. By making the light transmittance of the base layer at a wavelength of 370 nm within the above range, post-curing of the first pressure-sensitive adhesive layer is possible by irradiating active energy rays from the second pressure-sensitive adhesive layer side, and an adherend that does not transmit ultraviolet rays also on the first pressure-sensitive adhesive layer side. Can be stacked.

The light transmittance of the substrate layer at a wavelength of 370 nm was measured using an ultraviolet visible spectrophotometer (type: Solid-Spec3700, manufactured by Shimadzu Corporation).

The thickness of the substrate layer is preferably 20 µm or more, more preferably 40 µm or more, and even more preferably 50 µm or more. Further, the thickness of the base layer is preferably 500 µm or less, more preferably 400 µm or less, and even more preferably 300 µm or less.

(First adhesive layer)

The first adhesive layer is an adhesive layer formed on one side of the substrate layer. The first pressure-sensitive adhesive layer has a property that can be cured after bonding to an adherend. That is, it is preferable that the 1st adhesive layer is an adhesive layer which has an active energy ray hardening ability.

Moreover, it is preferable that the 1st adhesive layer is an adhesive layer which has an active energy ray hardening ability. In the present specification, the pressure-sensitive adhesive layer having active energy ray curing ability may be referred to as a dual cure-type pressure-sensitive adhesive layer. Here, the pressure-sensitive adhesive layer having an active energy ray-curable ability is a pressure-sensitive adhesive layer that undergoes curing in multiple stages, and is, for example, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition having both thermosetting properties and active energy ray curing properties. In the present invention, the first pressure-sensitive adhesive layer has been subjected to a first step of heat curing, and it is preferable that the first pressure-sensitive adhesive layer can be cured by an activation energy in the second step. In the double-sided pressure-sensitive adhesive sheet of the present invention, the first pressure-sensitive adhesive layer is preferably laminated in a semi-cured state subjected to heat curing, and is preferably cured with activation energy after the first pressure-sensitive adhesive layer is bonded to the adherend. That is, in the double-sided pressure-sensitive adhesive sheet of the present invention, it is preferable that the first pressure-sensitive adhesive layer has an active energy ray curing ability. On the other hand, the curing step after the first adhesive layer is bonded to the adherend may be a multi-step curing step.

The thickness of the first pressure-sensitive adhesive layer is preferably 50 µm or more, more preferably 75 µm or more, and still more preferably 90 µm or more. Further, the thickness of the first pressure-sensitive adhesive layer is preferably 250 µm or less, more preferably 200 µm or less, and even more preferably 150 µm or less. By setting the thickness of the first pressure-sensitive adhesive layer within the above range, it is possible to more effectively increase the level difference followability. In addition, the outgassing resistance of the double-sided adhesive sheet can be improved.

The first adhesive layer may be an adhesive layer having a post-curing ability. Such a pressure-sensitive adhesive layer can be formed from, for example, (a) a dual cure type pressure-sensitive adhesive composition, or (b) a hydrogen-pull type cross-linking agent-containing pressure-sensitive adhesive composition. In the present invention, a pressure-sensitive adhesive layer having a post-curing ability can be obtained even when a pressure-sensitive adhesive composition containing a hydrogen drawing type crosslinking agent is used in addition to the dual cure type pressure-sensitive adhesive composition. Also in this case, a post-curing step can be performed by irradiating an active energy ray.

((a) dual cure adhesive composition)

It is preferable that the first adhesive layer is formed from a dual cure adhesive composition. The dual cure type pressure-sensitive adhesive composition includes a base polymer (A) comprising a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, a monomer (B), and a base polymer by heat. It is preferable to contain a crosslinking agent (C) reacting with (A), a polymerization initiator (D) which initiates a polymerization reaction of the monomer (B) by irradiation with an active energy ray, and a solvent (E).

In addition, in this specification, "(meth)acrylate" means containing both "acrylate" and "methacrylate", and "(meth)acrylic acid" means "acrylic acid" and "methacrylic acid. It means to include both.

<Base polymer (A)>

The base polymer (A) contains a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group. It is preferable that the base polymer has a degree of transparency that does not deteriorate the visibility of the display device. In addition, in this specification, a "unit" is a repeating unit (monomer unit) which comprises a polymer.

The non-crosslinkable (meth)acrylic acid ester unit (a1) is a repeating unit derived from an alkyl (meth)acrylate. (Meth) acrylate alkyl esters include (meth) methyl acrylate, (meth) ethyl acrylate, (meth) propyl acrylate, (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (meth) isobutyl acrylate, (meth) ) T-butyl acrylate, (meth) acrylate n-pentyl, (meth) acrylate n-hexyl, (meth) acrylate 2-ethylhexyl, (meth) acrylate n-octyl, (meth) acrylate isooctyl, (meth) acrylic acid n-nonyl, (meth) isononyl acrylate, (meth) acrylate n-decyl, (meth) acrylate isodecyl, (meth) acrylate n-undecyl, (meth) acrylate n-dodecyl, (meth) acrylate ste Aryl, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. These may be used individually by 1 type, and may use 2 or more types together.

Among the above alkyl (meth)acrylates, at least one selected from methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable from the viewpoint of increasing the adhesiveness.

Examples of the acrylic monomer unit (a2) having a crosslinkable functional group include a hydroxy group-containing monomer unit, an amino group-containing monomer unit, a glycidyl group-containing monomer unit, and a carboxyl group-containing monomer unit. These monomer units may be 1 type or 2 or more types.

The hydroxy group-containing monomer unit is a repeating unit derived from a 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, 2-hydroxypropyl (meth)acrylate, and (meth)acrylate. ) (Meth)acrylic acid [(mono, di or poly)alkylene glycol] such as monoacrylate (diethylene glycol), and (meth)acrylic acid lactones such as (meth)acrylate monocaprolactone.

Examples of the amino group-containing monomer unit include a repeating unit derived from an amino group-containing monomer such as (meth)acrylamide and allylamine.

The glycidyl group-containing monomer unit includes a repeating unit derived from a glycidyl group-containing monomer such as glycidyl (meth)acrylate.

Examples of the carboxy group-containing monomer unit include acrylic acid and methacrylic acid.

The content of the crosslinkable acrylic monomer unit (a2) in the base polymer (A) is preferably 0.01% by mass or more and 40% by mass or less. When the content of the crosslinkable acrylic monomer unit (a2) is more than the lower limit of the above range, it has sufficient crosslinking properties necessary to maintain the semi-cured state, and if it is less than the upper limit of the above range, necessary adhesive properties can be maintained.

The base polymer (A) may have monomer units other than the non-crosslinkable (meth)acrylic acid ester unit (a1) and the acrylic monomer unit (a2) having a crosslinkable functional group, if necessary. Other monomers can be copolymerized with non-crosslinkable (meth)acrylic acid esters and acrylic monomers having a crosslinkable functional group. For example, (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, vinylpyridine, etc. Can be mentioned. It is preferable that the content of the optional monomer unit in the base polymer (A) is 20% by mass or less.

The weight average molecular weight of the base polymer (A) is preferably 100,000 or more and 2 million or less. By setting the weight average molecular weight within the above range, the semi-cured state of the first pressure-sensitive adhesive layer can be maintained, and sufficient level difference followability can be secured. On the other hand, the weight average molecular weight of the base polymer (A) is a value before crosslinking with a crosslinking agent. The weight average molecular weight is measured by size exclusion chromatography (SEC) and is a value calculated on a polystyrene basis. As the base polymer (A), a commercially available one may be used, or one synthesized by a known method may be used.

The weight average molecular weight of the base polymer (A) can also be measured by gel permeation chromatography (GPC). In this case, the measurement conditions of gel permeation chromatography (GPC) are as follows.

Solvent: tetrahydrofuran (THF)

Column: Shodex KF801, KF803L, KF800L, KF800D (4 units manufactured by Showa Electric Works Co., Ltd. were connected and used)

Column temperature: 40°C

Sample concentration: 0.5% by mass

Detector: RI-2031plus (manufactured by JASCO)

Pump: RI-2080plus (manufactured by JASCO)

Flow rate (flow rate): 0.8 ml/min

Injection volume: 10µl

Calibration curve: Standard polystyrene Shodex standard polystyrene (manufactured by Showa Electric Co., Ltd.) A calibration curve by 10 samples of Mw=1,320-2,500,000 is used.

<Monomer (B)>

It is preferable that the monomer (B) contains at least one of a monofunctional monomer (B1) having at least one polymerizable unsaturated group and a polyfunctional monomer (B2) having two or more polymerizable unsaturated groups. The monomer (B) preferably contains either a monofunctional monomer (B1) or a polyfunctional monomer (B2), and may contain both a monofunctional monomer (B1) and a polyfunctional monomer (B2).

By containing the monomer (B), when the pressure-sensitive adhesive composition is thermally cured, the thermally cured pressure-sensitive adhesive layer is in a semi-cured state and can have an active energy ray curing ability.

As the polymerizable unsaturated group, a group containing an ethylenic double bond is preferable, and examples thereof include a (meth)acryloyl group and a vinyl group. Among them, a (meth)acryloyl group is particularly preferred.

Monofunctional monomers (B1) include pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, (meth)acrylate )Isononyl acrylate, (meth) acrylate n-decyl, (meth) acrylate isodecyl, (meth) acrylate n-undecyl, (meth) acrylate lauryl, (meth) acrylate stearyl, (meth) acrylate isoste At least one selected from aryl, isobornyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like is preferable.

Among these, pentyl (meth)acrylate, (meth)hexyl acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, (meth)acrylate having a melting point of 25°C or less, (meth)acrylate )Isononyl acrylate, (meth) acrylate n-decyl, (meth) acrylate isodecyl, (meth) acrylate n-undecyl, (meth) acrylate lauryl, (meth) acrylate isostearyl, (meth) acrylate iso At least one selected from bornyl and 2-ethylhexyl (meth)acrylate is particularly preferred.

As a polyfunctional monomer (B2), for example, di(meth)acrylate ethylene glycol, di(meth)acrylate triethylene glycol, di(meth)acrylic acid 1,3-butylene glycol, di(meth)acrylic acid 1,4- Butylene glycol, di(meth)acrylic acid 1,9-nonanediol, diacrylic acid 1,6-hexanediol, di(meth)acrylate polybutylene glycol, di(meth)acrylate neopentyl glycol, di(meth)acrylate tetra Polyvalents such as ethylene glycol, di(meth)acrylate tripropylene glycol, di(meth)acrylate polypropylene glycol, tri(meth)acrylate trimethylolpropane, tri(meth)acrylate pentaerythritol, tetra(meth)acrylate pentaerythritol, etc. (Meth)acrylic acid ester of alcohol, vinyl methacrylate, etc. are mentioned.

On the other hand, it is preferable that the monomer (B) does not have a functional group exhibiting reactivity with a functional group possessed by the acrylic monomer unit (a2). For example, the monomer (B) preferably has the same functional group as the acrylic monomer unit (a2) (for example, a hydroxy group) or does not have a functional group.

As for the monomer (B), any one of a monofunctional monomer (B1) or a polyfunctional monomer (B2) may be used alone, or two or more types of a monofunctional monomer (B1) and/or a polyfunctional monomer (B2) may be used in combination.

In the pressure-sensitive adhesive composition, the content of the monomer (B) is appropriately selected depending on the composition, molecular weight, and crosslinking density of the base polymer (A), and is not particularly limited, but is 5 parts by mass or more and 150 parts by mass per 100 parts by mass of the base polymer (A). It is preferable that it is the following. By making the content of the monomer (B) within the above range, it is possible to improve the processability by increasing the deformation/distortion prevention performance of the step-following property.

<crosslinking agent (C)>

The crosslinking agent (C) can be appropriately selected in consideration of the reactivity with the crosslinkable functional group of the base polymer (A). For example, it is possible to select 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, an isocyanate compound and an epoxy compound are preferable because the acrylic monomer unit (a2) having a crosslinkable functional group can be easily crosslinked. For example, when a hydroxy group is included as a crosslinkable functional group, it is more preferable to use an isocyanate compound from the reactivity of the hydroxy group.

As an isocyanate compound, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc. are mentioned, for example.

Epoxy compounds include, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl Glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidyl xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane Polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and the like.

The content of the crosslinking agent (C) in the pressure-sensitive adhesive composition is appropriately selected depending on the desired adhesion properties, etc., but is preferably 0.01 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the base polymer (A).

<Polymerization initiator (D)>

The polymerization initiator (D) may be any one capable of initiating the polymerization reaction of the monomer (B) by irradiation with active energy rays, and a known one such as a photopolymerization initiator may be used.

Here, "active energy ray" means having both energy among electromagnetic waves or charged particle rays, and includes 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 (D) include an acetophenone initiator, a benzoin ether initiator, a benzophenone initiator, a hydroxyalkylphenone initiator, a thioxanthone initiator, and an amine initiator.

Specific examples of the acetophenone initiator include diethoxyacetophenone and benzyl dimethyl ketal.

Specific examples of the benzoin ether initiator include benzoin and benzoin methyl ether.

Specific examples of the benzophenone initiator include benzophenone and methyl o-benzoylbenzoate.

Specific examples of the hydroxyalkylphenone initiator include 1-hydroxy-cyclohexyl-phenyl-ketone and the like.

Specific examples of the thioxanthone initiator include 2-isopropyl thioxanthone and 2,4-dimethyl thioxanthone.

Specific examples of the amine initiator include triethanolamine and ethyl 4-dimethylbenzoate.

The content of the polymerization initiator (D) in the pressure-sensitive adhesive composition is appropriately selected depending on the content of the monomer (B) or the amount of active energy radiation emitted during complete curing. Specifically, it is preferably 0.05% by mass or more and 10% by mass or less with respect to the total mass of the monomer (B).

<Solvent (E)>

The solvent (E) is used to improve the coating ability of the pressure-sensitive adhesive composition. Examples of the solvent (E) include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; Halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloropropane; Alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, and diacetone alcohol; Ethers such as diethyl ether, diisopropyl ether, dioxane, and tetrahydrofuran; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone; Esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; Polyols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate, and derivatives thereof.

The solvent (E) is preferably a solvent having no polymerizable unsaturated group and having a higher vapor pressure at 25° C. than the monofunctional monomer (b1). As a solvent that does not have a polymerizable unsaturated group and has a higher vapor pressure at 25°C than the monofunctional monomer (b1), hexane, heptane, cyclohexane, benzene, toluene, ethanol, isopropyl alcohol, diisopropyl ether, tetrahydro Furan, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and the like.

<Optional ingredients>

The pressure-sensitive adhesive composition may further contain a plasticizer. It is preferable that the plasticizer is a non-functional acrylic polymer. The non-functional acrylic polymer is a polymer composed of only acrylic monomer units having no functional groups other than an acrylate group, or a polymer composed of an acrylic monomer unit having no functional groups other than an acrylate group and a non-acrylic monomer unit having no functional group. Since the non-functional acrylic polymer does not crosslink with the base polymer (A), it is possible to improve the step-following property without affecting the adhesive properties.

The pressure-sensitive adhesive composition may contain components other than the above within a range that does not impair the effect of the present invention. Other components include known components as additives for pressure-sensitive adhesives. Examples thereof include antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, and light stabilizers such as hindered amine compounds.

((b) pressure-sensitive adhesive composition containing hydrogen drawing crosslinking agent)

The pressure-sensitive adhesive composition containing a hydrogen drawing crosslinking agent is a pressure-sensitive adhesive composition containing an acrylic polymer as a main component. Here, the "main component" refers to a component contained in 50% by mass or more with respect to the total mass of the pressure-sensitive adhesive composition.

As the acrylic polymer, it is preferable to use a copolymer containing a non-crosslinkable (meth)acrylic acid ester unit (a1) as a main component, and an acrylic monomer unit (a2) having a crosslinkable functional group thereto. In this specification, the "unit" is a repeating unit (monomer unit) constituting a polymer.

Examples of the non-crosslinkable (meth)acrylic acid ester unit (a1) constituting the acrylic polymer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and iso Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, isoste Alkyl (meth)acrylate monomers, such as an aryl (meth)acrylate, are mentioned. These may use 2 or more types together as needed.

Examples of the acrylic monomer unit (a2) having a crosslinkable functional group include carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, and fumaric anhydride, 2-hydroxyethyl (meth)acrylate, 4 -Hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and hydroxyl group-containing monomers such as polyethylene glycol (meth)acrylate, (meth)acrylamide, morpholylacrylamide, N,N-dimethyl And amino group-containing (meth)acrylic acid esters such as aminoethyl acrylate and N-tert-butylaminoethyl acrylate, and epoxy groups such as glycidyl (meth)acrylate. These may use 2 or more types together as needed.

The acrylic polymer may have monomer units other than the non-crosslinkable (meth)acrylic acid ester unit (a1) and the acrylic monomer unit (a2) having a crosslinkable functional group, if necessary. Other monomers may be those that can be copolymerized with non-crosslinkable (meth)acrylic acid esters and acrylic monomers having a crosslinkable functional group. Other monomers include, for example, (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, and vinylpyridine.

The weight average molecular weight of the acrylic polymer is preferably 100,000 or more and 2 million or less, and more preferably 300,000 or more and 1.5 million or less. By setting the weight average molecular weight within the above range, sufficient durability and flexibility can be ensured. On the other hand, the weight average molecular weight of the acrylic polymer is a value before crosslinking with a crosslinking agent. The weight average molecular weight is measured by size exclusion chromatography (SEC) and is a value calculated on a polystyrene basis. In addition, the weight average molecular weight of the acrylic polymer can also be measured by gel permeation chromatography (GPC).

When polymerizing the acrylic polymer, a solution polymerization method can be applied, for example. As a solution polymerization method, an ion polymerization method, a radical polymerization method, etc. are mentioned. In that case, examples of the solvent used include tetrahydrofuran, chloroform, ethyl acetate, toluene, hexane, acetone, and methyl ethyl ketone.

The pressure-sensitive adhesive composition containing a hydrogen drawing type crosslinking agent contains a hydrogen drawing type photopolymerization initiator. Examples of the hydrogen drawing photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 2,4, 6-trimethylbenzophenone, 4-methylbenzophenone, thioxanthone, 2-chloro thioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, camphorquinone, di Benzosuberone, 2-ethylanthraquinone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, benzyl, 9,10-phenanthrenequinone, and the like. Among them, benzophenone, methylbenzophenone and 2,4,6-trimethylbenzophenone are preferable.

The pressure-sensitive adhesive composition containing a hydrogen drawing type crosslinking agent may contain a crosslinking agent in addition to the hydrogen drawing type photopolymerization initiator. As another crosslinking agent, an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, a metal chelate compound, a butylated melamine compound, etc. are mentioned, for example.

The content of the hydrogen drawing type photoinitiator in the hydrogen drawing type crosslinking agent-containing pressure-sensitive adhesive composition is appropriately selected according to the desired adhesive properties, and is not particularly limited, but, for example, 0.01 parts by mass or more and 20 parts by mass or less is preferable based on 100 parts by mass of the acrylic polymer. Do.

A solvent may be contained in the pressure-sensitive adhesive composition containing a hydrogen drawing crosslinking agent. As a solvent, for example, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, cyclohexanone, ethyl acetate, Butyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone, and the like are used. These may be used individually by 1 or more types, and may be used by mixing 2 or more types.

The pressure-sensitive adhesive composition containing a hydrogen drawing crosslinking agent may contain other components other than the above within a range that does not impair the effects of the present invention. Other components include known components as additives for pressure-sensitive adhesives. Examples thereof include antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, and light stabilizers such as hindered amine compounds.

(2nd adhesive layer)

The second adhesive layer is an adhesive layer formed on the other side of the substrate layer. The thickness of the second pressure-sensitive adhesive layer is 5 μm or more and 75 μm or less.

The thickness of the second pressure-sensitive adhesive layer may be 5 µm or more, preferably 10 µm or more. Further, the thickness of the second pressure-sensitive adhesive layer may be 75 μm or less, preferably 60 μm or less, and more preferably 50 μm or less. By setting the thickness of the second pressure-sensitive adhesive layer within the above range, outgassing resistance can be effectively improved.

It is preferable that the second pressure-sensitive adhesive layer is formed from a second pressure-sensitive adhesive composition containing a base polymer as a main component. The base polymer preferably contains at least one selected from acrylic polymers, rubber polymers, silicone polymers, urethane polymers and polyester polymers. Among them, the base polymer preferably contains at least one selected from acrylic polymers, rubber polymers and silicone polymers, more preferably contains at least one selected from acrylic polymers and rubber polymers, and contains acrylic polymers. It is more preferable.

Other components included in the second pressure-sensitive adhesive composition are the same as other components included in the first pressure-sensitive adhesive composition.

It is preferable that the thickness of the second pressure-sensitive adhesive layer is thinner than that of the first pressure-sensitive adhesive layer. When the thickness of the first pressure-sensitive adhesive layer is set to A and the thickness of the second pressure-sensitive adhesive layer is set to B, it is preferably A>B, more preferably A>1.5B, and still more preferably A>2B. By making the relationship between the thickness of the 1st adhesive layer and the 2nd adhesive layer into the said relation, outgassing resistance and the level difference followability can be improved more effectively.

(Double-sided adhesive sheet with peeling sheet formed)

The present invention may also relate to a double-sided adhesive sheet in which a release sheet is laminated on at least one side of the above-described double-sided adhesive sheet. The release sheet is laminated on at least one side of the double-sided pressure-sensitive adhesive sheet, and is preferably laminated on both sides of the double-sided pressure-sensitive adhesive sheet.

The release sheet is a sheet having releasability on at least one side. Examples of the release sheet include a peelable laminated sheet having a release sheet base material and a release agent layer formed on one side of the release sheet base material, and a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity base material.

Papers and polymer films are used as the base material for a release sheet in the peelable laminated sheet. As the release agent constituting the release agent layer, a general-purpose addition-type or condensation-type silicone-based release agent or a long-chain alkyl group-containing compound is used, for example. In particular, a highly reactive addition type silicone-based release agent is preferably used.

Specific examples of the silicone release agent include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone, and KS-3600, KS-774, X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. and the like. In addition, it is preferable to 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 in the silicon-based release agent. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone, KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Industries, Ltd.

In order to facilitate peeling of the peeling sheet, it is preferable that peeling properties are different between one peeling sheet and the other peeling sheet. That is, if the peelability from one side and the peelability from the other are different, it becomes easy to first peel only the peeling sheet with high peelability. In that case, the peelability of one peeling sheet and the other peeling sheet may be adjusted according to the bonding method and the bonding procedure.

When applying the pressure-sensitive adhesive composition on the release sheet, it can be carried out using a known coating device. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and the like. The coating film heating can be performed using a known heating device such as a heating oven and an infrared lamp.

(Method of manufacturing double-sided adhesive sheet)

The manufacturing method of the double-sided adhesive sheet of the present invention includes a step of obtaining a curable first adhesive layer after bonding, a step of obtaining a second adhesive layer having a thickness of 5 μm or more and 75 μm or less, and a light transmittance of 50% or more at a wavelength of 370 nm. It includes a step of bonding a first pressure-sensitive adhesive layer to one side of the substrate layer, and a step of bonding a second pressure-sensitive adhesive layer to the other side of the base material layer.

It is preferable that the process of obtaining a 1st adhesive layer is a process of coating a 1st adhesive composition on a 1st release sheet. Coating of the first pressure-sensitive adhesive composition can be performed using a known coating device. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and the like. It is preferable to form a heat drying process after coating, and it is preferable to use a well-known heating apparatus, such as a heating oven and an infrared lamp, in the heat drying process.

In the step of forming the first pressure-sensitive adhesive layer, it is preferable to form a first pressure-sensitive adhesive having a thickness of 50 μm or more and 250 μm or less. In this case, the coating amount of the first pressure-sensitive adhesive composition can be appropriately determined according to the solid content concentration or viscosity of the pressure-sensitive adhesive composition.

It is preferable that the process of obtaining a 2nd adhesive layer is a process of coating a 2nd adhesive composition on a 2nd release sheet. As the coating method of the second pressure-sensitive adhesive composition, the above-described coating method can be mentioned in the same manner.

In the step of forming the second pressure-sensitive adhesive layer, it is preferable to form a second pressure-sensitive adhesive having a thickness of 5 μm or more and 75 μm or less.

In the step of bonding the first pressure-sensitive adhesive layer to one side of the substrate layer having a light transmittance of 50% or more with a wavelength of 370 nm, and the step of bonding the second pressure-sensitive adhesive layer to the other side of the base layer, The 1 adhesive layer and the 2nd adhesive layer are attached|attached respectively.

(How to use double-sided adhesive sheet)

The method of using the double-sided pressure-sensitive adhesive sheet of the present invention is preferably a method of completely curing the first pressure-sensitive adhesive layer by bonding with an adherend and irradiating an active energy ray when the first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is in a semi-cured state. The adherend may have a step, and examples of such adherend include a decorative base layer having a decorative layer.

When bonding the double-sided adhesive sheet to the decorative base layer having the decorative layer, the active energy ray is irradiated from the second adhesive layer side. Since the first pressure-sensitive adhesive layer is in a semi-cured state before irradiation with an active energy ray, it is possible to follow the step difference between the decorative layer and the decorative base layer. After bonding the double-sided pressure-sensitive adhesive sheets and following the steps, the first pressure-sensitive adhesive layer is completely cured with an active energy ray, thereby increasing the cohesive force of the first pressure-sensitive adhesive layer and improving the adhesion to the decorative base layer.

Examples of active energy rays include ultraviolet rays, electron rays, visible rays, X rays, ion rays, and the like, and 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 ultra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, and the like can be used.

As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as a Cockcroft Walton type, a Van Degraf type, a resonance transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type can be used.

After completely curing the first pressure-sensitive adhesive layer, it is preferable to bond the adherend to the second pressure-sensitive adhesive layer. The second pressure-sensitive adhesive layer need not be a pressure-sensitive adhesive layer having a post-curing ability, and can be bonded to an adherend without irradiating an active energy ray. That is, the second adhesive layer is an active energy ray non-curable adhesive layer.

It is preferable that the adherend attached to the second adhesive layer is an optical member such as a display device. As a display device, a liquid crystal display device (liquid crystal display panel), a plasma display device (plasma display panel), an organic electroluminescent display device (organic EL panel), etc. are mentioned, for example.

(Laminate)

<First aspect>

The present invention may also relate to a laminate in which another layer is laminated in addition to the above-described double-sided pressure-sensitive adhesive sheet. As a first aspect of such a laminate, a laminate comprising the above-described double-sided pressure-sensitive adhesive sheet, a decorative base layer laminated on the first pressure-sensitive adhesive layer, and a display device laminated on the second pressure-sensitive adhesive layer may be mentioned. Here, the decorative base layer has a decorative layer on a part of one surface, and the surface having the decorative layer and the first adhesive layer are bonded to each other.

2 is a schematic cross-sectional view illustrating the configuration of a laminate 200 formed by bonding adherends using the double-sided adhesive sheet of the present invention. As shown in FIG. 2, a decorative base layer 20 having a decorative layer 25 is stacked on the first adhesive layer 12, and an adherend 30 is stacked on the second adhesive layer 14. . Here, it is preferable that the adherend 30 is a display device. As a display device, a liquid crystal display device (liquid crystal display panel), a plasma display device (plasma display panel), an organic electroluminescent display device (organic EL panel), etc. are mentioned, for example.

<Decorative base layer>

In the present invention, the decorative base layer may have a property that does not transmit ultraviolet rays. In the present invention, when curing the first pressure-sensitive adhesive layer, active energy rays can be irradiated from the second pressure-sensitive adhesive layer side. For this reason, the adherend to which the first pressure-sensitive adhesive layer is bonded may not transmit ultraviolet rays, and the double-sided pressure-sensitive adhesive sheet of the present invention can be used for bonding various adherends.

In the laminate, the decorative base layer may have a multilayer structure. When the decorative base layer has a multilayer structure, it is preferable that the decorative base layer has, for example, a base resin layer and a functional layer.

Examples of the functional layer include at least one layer selected from a primer layer and a hard coating layer. That is, it is preferable that the decorative base layer includes at least one layer selected from a base resin layer, a primer layer, and a hard coat layer.

<Primer layer>

It is preferable that the primer layer is an undercoat layer of the base resin layer. By forming the primer layer, it is possible to minimize the influence of the solvent applied to the base resin layer when a solvent-type pressure-sensitive adhesive layer is used. On the other hand, when the base layer has a multilayer structure of the base resin layer and the primer layer, the thickness of the base resin layer is greater than the thickness of the primer layer, and these thicknesses can distinguish both.

The resin constituting the primer layer includes, for example, an epoxy resin. Epoxy resin can be used either one-component curing type or two-component curing type. Further, a water-soluble epoxy resin is particularly preferably used. Examples of water-soluble epoxy resins include polyamide epoxy resins. The polyamide epoxy resin is obtained by reacting epichlorohydrin with a polyamide polyamine obtained by reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid.

When a water-soluble epoxy resin is used as the resin for forming the primer layer, other water-soluble resins such as polyvinyl alcohol-based resin may be mixed in order to further improve coatability. In addition to partially saponified polyvinyl alcohol or completely saponified polyvinyl alcohol, polyvinyl alcohol-based resins are modified polyvinyl alcohol such as carboxyl group modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, methylol group modified polyvinyl alcohol, amino group modified polyvinyl alcohol. Vinyl alcohol-based resin may be used.

The resin constituting the primer layer is preferably used in a state dissolved in a solvent. It is preferable to use water as the solvent used at this time, but you may use an organic solvent. Organic solvents include aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as ethyl acetate and isobutyl acetate, methylene chloride, trichloroethylene, chloroform, etc. Common organic solvents such as alcohols such as chlorinated hydrocarbons, ethanol, 1-propanol, 2-propanol, and 1-butanol may also be used.

<Hard coating layer>

It is preferable that the hard coating layer is a layer formed in order to increase decorative printing aptitude. In addition, the hard coat layer may increase the strength and durability of the laminate.

It is preferable that the hard coating layer contains a hard component for imparting hardness. As a hard component, a crosslinked polymer is mentioned, for example. As a crosslinked polymer, a monofunctional monomer polymer and a polyfunctional monomer polymer are mentioned. The polyfunctional monomer polymer is preferably a polymerizable monomer polymer containing a trifunctional or higher polyfunctional monomer, and more preferably a polymerizable monomer polymer containing a tetrafunctional or higher polyfunctional monomer. For example, a mixed monomer copolymer of a trifunctional or higher functional monomer and a difunctional monomer can also be preferably illustrated. In addition, oligomers are also contained in the monomer mentioned here.

Although the kind of monomer which can be used for obtaining a crosslinked polymer is not specifically limited, For example, an acrylic monomer etc. can be illustrated preferably. Specifically, dipropylene glycol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol (weight average molecular weight 600) di(meth)acrylate , Propylene oxide-modified neopentyl glycol di (meth) acrylate, modified bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, polyethylene glycol (weight average molecular weight 400) di (meth) acrylate Bifunctional (meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxytri(meth)acrylate, polyethertri(meth)acrylate, etc. , Trifunctional (meth)acrylates such as glycerin propoxytri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, ditrimethylolpropanetetra(meth) (Meth)acrylates of tetrafunctional or higher functionalities such as acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. Can be mentioned.

The organic compound monomer or oligomer having a polymerizable unsaturated group may be thermosetting or active energy ray-curable.

The hard coating layer may contain a flexible component. Examples of the flexible component include tricyclodecanmethyloldi(meth)acrylate, ethylene oxide-modified di(meth)acrylate of bisphenol F, ethylene oxide-modified di(meth)acrylate of bisphenol A, and ethylene of isocyanuric acid. Difunctional (meth)acrylates such as oxide-modified di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylpropane Trifunctional (meth)acrylates, such as propylene oxide-modified tri(meth)acrylate and ethylene oxide-modified tri(meth)acrylate of trimethylpropane, urethane (meth)acrylate, polyester (meth)acrylate, polyether ( Meth)acrylate, etc. are mentioned.

Moreover, the hard coat layer may contain inorganic particles and/or organic particles. When it contains inorganic particles and/or organic particles, it is preferable from the viewpoint of suppressing curing shrinkage. Examples of the inorganic particles include inorganic oxide particles such as silicon dioxide particles, titanium dioxide particles, zirconium oxide particles, aluminum oxide particles, tin dioxide particles, antimony pentoxide particles, and antimony trioxide particles. Further, examples of the organic particles include resin particles such as acrylic resin, polystyrene, polysiloxane, melamine resin, benzoguanamine resin, polytetrafluoroethylene, cellulose acetate, polycarbonate, and polyamide.

When using inorganic particles, you may use reactive inorganic oxide particles treated with a coupling agent. When using organic particles, you may use reactive organic oxide particles treated with a coupling agent. By treating with a coupling agent, it is possible to increase the bonding strength with the acrylic polymer.

As a coupling agent, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ- Mercaptopropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-aminopropyl triethoxy aluminum, and the like. These may be used individually by 1 type, and may use 2 or more types together.

The thickness of the hard coating layer is not particularly limited, but, for example, it is preferably 0.5 µm or more, more preferably 1.0 µm or more, and even more preferably 2.0 µm or more. Further, the thickness of the hard coating layer is preferably 100 µm or less, and more preferably 50 µm or less.

<Decorative layer>

A decorative layer is formed on one side of the decorative base layer. The decorating layer may be a decorating printing layer formed by printing. Examples of the printing method for constituting the decorative printing layer include gravure printing and screen printing. The decorative layer may be a decorative printing layer for concealing the electrode on a frame, or may be a printing pattern having design.

The paint for constituting the decorative printing layer is not particularly limited, and a known paint can be used. Examples of the paint include ultraviolet curable ink and oxidation polymerization ink.

The thickness of the decorative layer is preferably 5 µm or more, more preferably 7 µm or more, and even more preferably 10 µm or more. In addition, the thickness of the decorative layer is preferably 50 µm or less, more preferably 30 µm or less, and even more preferably 25 µm or less. On the other hand, the thickness of the decorative layer may be made thicker than 50 μm, if necessary. In this case, by appropriately adjusting the thickness of the first adhesive layer, it is possible to follow the step difference between the decorative layer and the base layer.

<2nd aspect>

As a 2nd aspect of a laminated body, in addition to the laminated body of 1st aspect, a laminated body which further has a 3rd adhesive layer and a surface cover layer is mentioned. The laminate of the second aspect further has a third adhesive layer and a surface cover layer, has a third adhesive layer on the decorative base layer, and has a surface cover layer on the third adhesive layer.

3 is a schematic cross-sectional view illustrating a configuration of a layered product 200 according to a second aspect. As shown in FIG. 3, a third adhesive layer 40 is laminated on the decorative base layer 20 and a surface cover layer 50 is further laminated on the third adhesive layer 40.

As the surface cover layer 50, a glass plate and a resin layer are mentioned, for example. Specific examples of the glass plate include those made of inorganic materials such as soda glass, alkali-free glass, and tempered glass. The surface cover layer is preferably a surface resin layer, and in this case, a number composed of a transparent resin such as polyethylene terephthalate resin (PET resin), polycarbonate resin (PC resin), and polymethyl methacrylate resin (PMMA resin) Strata is preferably used. These surface resin layers may have properties that do not transmit ultraviolet rays.

It is preferable that the 3rd adhesive layer is formed from the 3rd adhesive composition containing a base polymer as a main component. The base polymer preferably contains at least one selected from acrylic polymers, rubber polymers, silicone polymers, urethane polymers and polyester polymers. Among them, the base polymer preferably contains at least one selected from acrylic polymers, rubber polymers and silicone polymers, more preferably contains at least one selected from acrylic polymers and rubber polymers, and contains acrylic polymers. It is more preferable.

The thickness of the third pressure-sensitive adhesive layer may be 5 µm or more, preferably 10 µm or more. Further, the thickness of the third pressure-sensitive adhesive layer may be 75 μm or less, preferably 60 μm or less, and more preferably 50 μm or less.

(Method of manufacturing a laminate)

The present invention also relates to a method of manufacturing a laminate. In the method for producing a laminate of the present invention, the first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is brought into contact with the side of the decorative layer of the decorative base layer having the decorative layer on a part of one surface, and activated from the side of the second pressure-sensitive adhesive layer in that state. It includes a step of completely curing the first pressure-sensitive adhesive layer by irradiating energy rays, and a step of attaching a display device to the second pressure-sensitive adhesive layer. In the step of bringing the first pressure-sensitive adhesive layer into contact with the surface on the side of the decorative layer of the decorative base layer having the decorative layer on a part of one surface, the first pressure-sensitive adhesive layer is preferably in a semi-cured state.

Examples of the active energy ray include the above-described energy rays, and ultraviolet rays or electron rays are preferable, and ultraviolet rays are particularly preferable.

The irradiation output of ultraviolet rays is preferably such that the accumulated light amount is 100 mJ/cm 2 or more and 10000 mJ/cm 2 or less, and more preferably 500 mJ/cm 2 or more and 5000 mJ/cm 2 or less.

In the method for producing a laminate, since the first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is in a semi-cured state before irradiation with active energy rays, the pressure-sensitive adhesive layer can follow the irregularities even if the adherend has a stepped portion. In this way, after bonding the pressure-sensitive adhesive sheets and following the irregularities, the first pressure-sensitive adhesive layer is completely cured with active energy rays, thereby increasing the cohesive strength of the first pressure-sensitive adhesive layer and improving the adhesion to the adherend.

In the present invention, when completely curing the first pressure-sensitive adhesive layer with an active energy ray, an active energy ray is irradiated from the second pressure-sensitive adhesive layer side. By irradiating an active energy ray from the side of the second pressure-sensitive adhesive layer, even when the first pressure-sensitive adhesive layer is bonded to the decorative base layer having a decorative layer, it becomes possible to uniformly and completely cure the first pressure-sensitive adhesive layer. This is due to the fact that there is no place where irradiation of active energy rays is hindered by the decorative layer.

After completely curing the first pressure-sensitive adhesive layer, it is preferable to bond the adherend to the second pressure-sensitive adhesive layer. The second pressure-sensitive adhesive layer need not be a pressure-sensitive adhesive layer having a post-curing ability, and can be bonded to an adherend without irradiating an active energy ray. On the other hand, it is preferable that the adherend attached to the second pressure-sensitive adhesive layer is an optical member such as a display device.

When the laminate further has a third pressure-sensitive adhesive layer and a surface cover layer in addition to the laminate of the first aspect, a decorative substrate having a third pressure-sensitive adhesive layer bonded to the surface cover layer and a decorative layer additionally provided on the third pressure-sensitive adhesive layer The layers are put together. At the time of bonding, it is preferable to perform roll bonding. The first adhesive layer side of the double-sided adhesive sheet is bonded to the decorative base layer.

Example

Hereinafter, the characteristics of the present invention will be described in more detail with reference to Examples and Comparative Examples. Materials, amounts used, ratios, treatment contents, treatment procedures, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the specific examples shown below.

(Example 1)

The first adhesive (manufactured by Shintaekhwasung, DC124) was applied on one side of the separator A (manufactured by Oji Ftex, 100RL-07V (10.5)) with an applicator and dried at 100°C for 2 minutes, having a thickness of 100 μm. A first adhesive layer was formed. Next, a 1st adhesive layer was pasted on one side of a PET film (Toray company make, Lumirror U483, thickness 75 micrometers).

A second pressure-sensitive adhesive composition (SA151, manufactured by Shintaekhwasung, Inc.) was coated on one side of the separator B (manufactured by Oji Ftex, 75RL-07V (6.5)) with an applicator and dried at 100°C for 2 minutes, and the thickness was 25 μm A phosphorus second adhesive layer was formed. Next, a second adhesive layer was pasted on the opposite side of the PET film to which the first adhesive layer was attached. In this way, the double-sided adhesive sheet of Example 1 was obtained. Table 1 shows the light transmittance of the base film (PET film) at a wavelength of 370 nm.

(Example 2)

A double-sided pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that SA151 of the second pressure-sensitive adhesive composition was changed to NA021 manufactured by Shintaekhwasung.

(Comparative Example 1)

Except having changed the PET film of the base film to an SRF film, it carried out similarly to Example 1, and obtained the double-sided adhesive sheet. Table 1 shows the light transmittance of the base film at a wavelength of 370 nm.

(Comparative Example 2)

The first pressure-sensitive adhesive composition was changed to DC126 manufactured by Syntaek Hwaseong, and the thickness was changed as shown in Table 1. A double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer were bonded without interposing the base film.

(Comparative Example 3)

A single-layer double-sided pressure-sensitive adhesive sheet was obtained using DC126 manufactured by Syntaek Hwasung as the first pressure-sensitive adhesive composition.

(Comparative Example 4)

The same as in Example 1, except that the first pressure-sensitive adhesive composition was changed to DC126 manufactured by Syntaek Hwaseong, and the thickness was changed as shown in Table 1, and the second adhesive composition was changed to DC121 manufactured by Syntaekhwasung. Thus, a double-sided adhesive sheet was obtained.

(Comparative Example 5)

A single-layer double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Comparative Example 3, except that SA037 manufactured by Syntaek Hwaseong Co., Ltd. was used as the first pressure-sensitive adhesive composition, and the thickness was changed as shown in Table 1.

(Comparative Example 6)

A single-layer double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Comparative Example 3, except that NA017 manufactured by Syntaek Hwaseong Co., Ltd. was used as the first pressure-sensitive adhesive composition, and the thickness was changed as shown in Table 1.

(Comparative Example 7)

A double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Comparative Example 4, except that SA034 manufactured by Syntaek Hwaseong Co., Ltd. was used as the first pressure-sensitive adhesive composition, and the thickness was changed as shown in Table 1.

(evaluation)

(Ultraviolet ray transmittance)

The ultraviolet transmittance of the substrate layer was measured using an ultraviolet visible spectrophotometer (model: Solidspec 3700, manufactured by Shimadzu Corporation). Specifically, the spectral transmittance at a wavelength of 370 nm was measured.

(Foam resistance (out gas resistance))

Screen printing was performed on the PC side of a coextruded film (brand name: MR58) of PC (polycarbonate resin) and PMMA (polymethyl methacrylate resin) manufactured by Mitsubishi Gas Chemical Co., Ltd. to form a decorative printing layer. The thickness of the decorative printing layer was 20 µm.

Next, the double-sided pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples was cut into a size of 55 mm×80 mm, the separator A was peeled off, and the first pressure-sensitive adhesive layer was attached to the side of the decorative printing layer of the coextrusion film (MR58). did.

Further, the separator B was peeled off, the second pressure-sensitive adhesive layer was bonded to the glass plate, and an autoclave defoaming treatment was performed under the conditions of 40°C, 0.5 MPa, and 30 minutes. The laminate thus obtained was placed in an environment of 85° C. and 0 to 3% relative humidity for 24 hours, and after such an endurance test, the laminate was observed from the side of the coextruded film of PC/PMMA, and the presence or absence of bubbles was evaluated as follows. It was evaluated as a standard.

(Circle): There are no air bubbles in the central part of the laminated body (a region 10 mm or more away from the edge of the decorative layer).

?: There are bubbles in the center of the layered product, but they are bubbles with a diameter of less than 200 µm.

X: There are large air bubbles of 200 µm or more in diameter in the central portion of the laminate.

(Step followability)

A laminate was produced by the same method as the foam resistance evaluation method, and after degassing treatment and durability test were performed in the same manner as above, the laminate was observed from the side of the coextruded film of PC/PMMA, and the frame printing periphery (decorative layer and, The presence or absence of bubble generation (step difference followability) in the area|region less than 10 mm away from the edge of a decorative layer was evaluated by the following evaluation criteria.

○: There are no air bubbles around the frame printing.

?: Bubbles are generated in the corners of the frame printing, but there are no bubbles around the long and short sides.

X: Bubbles exist around both the corners and sides of the frame printing.

It can be seen that the double-sided pressure-sensitive adhesive sheet obtained in Examples is excellent in gas resistance and step followability. On the other hand, the double-sided pressure-sensitive adhesive sheet obtained in the comparative example was not compatible with outgassing resistance and step followability.

A laminate could also be produced using the double-sided adhesive sheet obtained in Examples. The release sheet on the side of the first adhesive layer of the double-sided pressure-sensitive adhesive sheet was peeled and bonded to the decorative base layer having a decorative layer, and thereafter, the release sheet on the second adhesive layer side was peeled and roll-bonded to the display device.

10 base layer
12 first adhesive layer
14 Second adhesive layer
20 decorative base layer
25 decorative layer
30 adherend
40 Third adhesive layer
50 surface cover layer
100 double sided adhesive sheet
200 laminate

Claims (8)

A substrate layer having a light transmittance of 50% or more at a wavelength of 370 nm, and
A first pressure-sensitive adhesive layer formed on one side of the base layer and capable of curing after bonding,
It has a second pressure-sensitive adhesive layer formed on the other side of the base layer and having a thickness of 5 μm or more and 75 μm or less,
The first pressure-sensitive adhesive layer has active energy ray curing ability,
When the thickness of the first pressure-sensitive adhesive layer is A and the thickness of the second pressure-sensitive adhesive layer is B, the double-sided pressure-sensitive adhesive sheet of A>B. delete The method of claim 1,
A double-sided pressure-sensitive adhesive sheet having a thickness of the first pressure-sensitive adhesive layer of 50 μm or more and 250 μm or less. The method of claim 1,
The first pressure-sensitive adhesive layer is a double-sided pressure-sensitive adhesive sheet that is bonded to a decorative base layer having a decorative layer on a part of one surface. The method of claim 1,
The second pressure-sensitive adhesive layer is a double-sided pressure-sensitive adhesive sheet that is bonded to a display device. A laminate comprising the double-sided pressure-sensitive adhesive sheet of claim 1, a decorative base layer laminated on the first pressure-sensitive adhesive layer, and a display device laminated on the second pressure-sensitive adhesive layer,
The decorative base layer has a decorative layer on a part of one surface, and the surface having the decorative layer and the first adhesive layer are bonded to each other. The method of claim 6,
It further has a 3rd adhesive layer and a surface cover layer,
A laminate having the third adhesive layer on the decorative base layer and the surface cover layer on the third adhesive layer. The first pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet of claim 1 is brought into contact with the side of the decorative layer side of the decorative base layer having the decorative layer on a part of one surface,
In that state, irradiating active energy rays from the side of the second pressure-sensitive adhesive layer to completely cure the first pressure-sensitive adhesive layer, and
A method for manufacturing a laminate comprising a step of bonding a display device to the second pressure-sensitive adhesive layer.

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