TW201816039A - Laminated adhesive sheet - Google Patents

Abstract

The present invention addresses the problem of providing a laminated adhesive sheet having an excellent step conformability and heat resistance. The present invention relates to a laminated adhesive sheet having a first surface adhesive agent layer, an intermediate resin layer, and a second surface adhesive agent layer in this order, wherein the first surface adhesive agent layer and the second surface adhesive agent layer are each a solvent-type adhesive agent layer including a (meth)acrylic acid ester polymer (A) and a hydrogen abstraction type photopolymerization initiator (B).

Description

   Laminated adhesive sheet   

The present invention relates to a laminated adhesive sheet. More specifically, this invention relates to the laminated adhesive sheet which has a 1st surface adhesive layer, an intermediate resin layer, and a 2nd surface adhesive layer.

In recent years, a display device such as a liquid crystal display (LCD) or an input device such as a touch panel has been widely used in various fields. In the manufacture of such display devices or input devices, a transparent adhesive sheet is used for the purpose of bonding optical members. For such an adhesive sheet, not only the function of firmly bonding the optical members is required, but also durability or heat resistance is required.

Furthermore, when the optical member is a member having a step, the step followability is required for the adhesive sheet. In order to balance adhesion, durability, and unevenness followability, it has been proposed to use an adhesive sheet having after cure (for example, Patent Document 1). In the case of using such an adhesive sheet having post-curing properties, first, the adhesive sheet in a semi-hardened state is adhered to the adherend, so that it sufficiently follows the uneven shape. Then, in this state, it is irradiated with active energy rays to thereby completely harden it, and exhibits strong adhesion and durability.

A laminated adhesive sheet having two or more adhesive layers is known as an adhesive sheet capable of exhibiting step-following followability. For example, Patent Document 2 discloses a laminated adhesive sheet having a first adhesive layer and a second adhesive layer. Here, at least one layer of the first adhesive layer and the second adhesive layer contains an acrylate polymer, a polyfunctional (meth) acrylate, a cross-linking agent, and a reaction initiator, and the first adhesive layer has no Solvent-based adhesive layer.

Further, Patent Document 3 discloses a laminated adhesive sheet having an intermediate resin layer and a pressure-sensitive adhesive layer as a front and back surface layer. Here, the pressure-sensitive adhesive layer is a solvent-free adhesive layer containing a (meth) acrylate copolymer and a dehydrogenated photopolymerization initiator.

Further, Patent Document 4 discloses a laminated adhesive sheet having a first adhesive layer and a second adhesive layer. Here, the first adhesive layer system contains a (meth) acrylate copolymer and a crosslinking agent and a photopolymerization initiator, and the second adhesive layer system contains a (meth) acrylate copolymer and a crosslinking agent. In addition, the second adhesive layer is formed by crosslinking by a heating reaction.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2010-261029

[Patent Document 2] Japanese Patent No. 4806630

[Patent Document 3] Japanese Patent No. 5174204

[Patent Document 4] Japanese Patent No. 5547538

However, when the pressure-sensitive adhesive sheet described in Patent Documents 1 to 4 is bonded to an adherend having a step difference, the step followability may not be sufficient. In addition, the conventional adhesive sheet may have insufficient heat resistance, or may have problems such as generation of bubbles when left in a high-temperature environment for a long time. That is, the conventional adhesive sheet does not sufficiently balance the step-followability and heat resistance, and needs to be improved.

Therefore, in order to solve such a problem of the conventional technology, the inventors of the present case conducted a review with the purpose of providing a laminated adhesive sheet having excellent step-following and heat resistance.

The inventors of the present invention conducted intensive research in order to solve the above-mentioned problems. As a result, they found that the first surface adhesive layer, the intermediate resin layer, and the second surface adhesive layer were sequentially laminated and copolymerized with a (meth) acrylate-containing layer. The solvent-based adhesive of the combination (A) and the dehydrogenation-type photopolymerization initiator (B) constitutes the first surface adhesive layer and the second surface adhesive layer, respectively, and a laminated adhesive sheet having excellent followability and heat resistance can be obtained. .

Specifically, the present invention has the following configuration.

[1] A laminated adhesive sheet, which is a laminated adhesive sheet having a first surface adhesive layer, an intermediate resin layer, and a second surface adhesive layer in this order, wherein the first surface adhesive layer and the second surface adhesive layer are Each is a solvent-based adhesive layer containing a (meth) acrylate copolymer (A) and a dehydrogenated photopolymerization initiator (B).

[2] The laminated adhesive sheet according to [1], wherein the thickness of the first surface adhesive layer is A, the thickness of the intermediate resin layer is B, and the thickness of the second surface adhesive layer is C In this case, the value of A / B is 0.23 or more and 0.46 or less, and the value of C / B is 0.23 or more and 0.46 or less.

[3] The laminated adhesive sheet according to [1] or [2], wherein when the thickness of the first surface adhesive layer is set to A and the thickness of the second surface adhesive layer is set to C, The value is 0.25 or more and 4.0 or less.

[4] The laminated adhesive sheet according to any one of [1] to [3], wherein the (meth) acrylate copolymer (A) contained in the first surface adhesive layer and the second surface adhesive layer, This is a non-crosslinkable (meth) acrylate unit having an alkyl group having 1 to 10 carbon atoms.

[5] The laminated adhesive sheet according to any one of [1] to [4], wherein the dehydrogenated photopolymerization initiator (B) contained in the first surface adhesive layer and the second surface adhesive layer, Contains at least one selected from the group consisting of diphenyl ketone, 4-methyldiphenyl ketone, and 2,4,6-trimethyldiphenyl ketone.

[6] The laminated adhesive sheet according to any one of [1] to [5], wherein the content of the dehydrogenated photopolymerization initiator (B) in the adhesive composition forming the first surface adhesive layer It is 0.5 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (meth) acrylate copolymer (A). In the adhesive composition forming the second surface adhesive layer, dehydrogenation photopolymerization is started. The content of the initiator (B) is 0.5 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (meth) acrylate polymer (A).

[7] The laminated adhesive sheet according to any one of [1] to [6], wherein the content of the crosslinking agent in the first surface adhesive layer is relative to the (meth) acrylate polymer (A) 100 parts by mass is 0.01 parts by mass or less; the content of the crosslinking agent in the second surface adhesive layer is 0.01 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate polymer (A).

[8] A method for manufacturing a laminated body, comprising contacting at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet of any one of [1] to [7] to The surface of the adherend is irradiated with active energy rays in this state to harden the surface adhesive layer.

[9] A method for using a laminated adhesive sheet, in which at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet of any one of [1] to [7] is brought into contact with The surface of the adherend is irradiated with active energy rays in this state to harden the surface adhesive layer.

According to the present invention, a laminated adhesive sheet having excellent step-following property and heat resistance can be obtained. The laminated adhesive sheet of the present invention is suitable for use in bonding optical members having step differences.

1‧‧‧ laminated adhesive sheet

11‧‧‧Intermediate resin layer

12a‧‧‧1st surface adhesive layer

12b‧‧‧Second surface adhesive layer

Fig. 1 is a sectional view showing an example of the constitution of a laminated adhesive sheet of the present invention.

The present invention is explained in detail below. The description of the constituent elements described below is based on typical embodiments or specific examples, but the present invention is not limited to such embodiments.

    (Laminated Adhesive Sheet)    

The present invention relates to a laminated adhesive sheet having a first surface adhesive layer, an intermediate resin layer, and a second surface adhesive layer in this order. The first surface adhesive layer and the second surface adhesive layer are solvent-based adhesive layers each containing a (meth) acrylate copolymer (A) and a dehydrogenated photopolymerization initiator (B).

Since the laminated adhesive sheet of the present invention has the above-mentioned structure, it has excellent step followability and heat resistance. When the laminated adhesive sheet of the present invention is attached to an adherend having a step difference, the surface adhesive layer follows the step difference of the adherend without a gap. Therefore, it is possible to suppress defects such as generation of bubbles in the step portion. In addition, even if the laminated adhesive sheet of the present invention is left in a high-temperature environment for a long time, it does not have air bubbles and is excellent in heat resistance.

Moreover, the laminated adhesive sheet system of the present invention is also excellent in operability. Here, superior operability means that occurrence of ooze defects is small. The so-called leakage defect refers to the exudation of the adhesive when the adhesive sheet that has been punched is heated or aggravated. In the present invention, the occurrence of such leakage defects is suppressed, and the operability is good.

The first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet each contain a dehydrogenated photopolymerization initiator (B), but a photopolymerization start other than the dehydrogenated photopolymerization initiator (B) The content of the agent is preferably 0.1% by mass or less. This configuration means that each surface adhesive layer uses a dehydrogenation type photopolymerization initiator as the photopolymerization initiator alone, and means that no photopolymerization initiator other than the dehydrogenation type photopolymerization initiator is intentionally added.

In addition, in the manufacturing step of the laminated adhesive sheet of the present invention, there is an advantage that it is not necessary to provide a curing step after forming each surface adhesive layer. Generally, the curing step usually takes several days, and there are problems that it takes time until the laminated adhesive sheet is shipped, or that it cannot be used immediately after the laminated adhesive sheet is manufactured. The laminated adhesive sheet of the present invention can exhibit better adhesive properties even without going through this curing step.

In the present invention, the first surface adhesive layer and the second surface adhesive layer are preferably an adhesive layer before being hardened formally. The so-called adhesive layer before formal hardening refers to an adhesive layer that has room for further active energy ray hardening. That is, the first surface adhesive layer and the second surface adhesive layer are preferably those having an active energy ray hardening ability. Such an adhesive layer having an active energy ray hardening ability can also be said to have a post-hardening property. In the case where the surface adhesive layer is post-hardened, the surface adhesive layer is in a semi-hardened state, and after the laminated adhesive sheet having such a surface adhesive layer is pasted to the adherend, the surface is irradiated with active energy rays to make the surface The adhesive layer is formally hardened. The surface adhesive layer in the semi-hardened state can follow the uneven structure of the adherend. With formal hardening, the surface adhesive layer is completely hardened and can exert a strong adhesion.

Here, the "semi-hardened state" refers to a case where the gel fraction increases by 0.5% or more after hardening by irradiation with active energy rays. The increase rate of the gel fraction is preferably 0.5% or more, and more preferably 1% or more. The so-called "formal hardening" means that the surface adhesive layer is completely hardened by active energy rays. The so-called fully hardened state refers to a case where the increase in the gel fraction when the active energy ray is irradiated is less than 0.5%. In the present invention, primary hardening may be performed in order to make the surface adhesive layer into a semi-hardened state, and secondary hardening may be performed in order to obtain a normal hardened state. Moreover, you may perform multi-stage hardening in order to make a semi-hardened state, and you may perform multi-stage hardening in order to make it a full hardened state.

The first surface adhesive layer and the second surface adhesive layer are preferably a semi-hardened adhesive layer, and more preferably an adhesive layer before formal hardening. In the present invention, it is preferable that the active energy ray is irradiated in any one of the semi-hardening step and the formal hardening step. Examples of active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Among them, it is preferable to use ultraviolet rays or electron beams as the active energy rays, and it is more preferable to use ultraviolet rays.

FIG. 1 is a cross-sectional view showing an example of the configuration of a laminated adhesive sheet of the present invention. As shown in FIG. 1, the laminated adhesive sheet 1 of the present invention sequentially laminates a first surface adhesive layer 12 a, an intermediate resin layer 11 and a second surface adhesive layer 12 b. It is preferably laminated according to a state where the first surface adhesive layer 12a and the intermediate resin layer 11 and the second surface adhesive layer 12b and the intermediate resin layer 11 are in contact with each other, but the first surface adhesive layer 12a and the intermediate resin may be laminated. Other layers are provided between the layers 11 and / or between the second surface adhesive layer 12 b and the intermediate resin layer 11.

In the present invention, since both surfaces of the laminated adhesive sheet 1 are surface adhesive layers (the first surface adhesive layer 12a and the second surface adhesive layer 12b), the laminated adhesive sheet 1 is a double-sided adhesive sheet.

A / B value when the thickness of the first surface adhesive layer of the laminated adhesive sheet of the present invention is A, the thickness of the intermediate resin layer is B, and the thickness of the second surface adhesive layer is C. It is preferably 0.23 or more and 0.46 or less, and the value of C / B is preferably 0.23 or more and 0.46 or less.

The value of A / B is more preferably 0.25 or more, and even more preferably 0.30 or more. The value of A / B is preferably 0.43 or less, and more preferably 0.40 or less.

The value of C / B is more preferably 0.25 or more, and still more preferably 0.30 or more. The value of C / B is preferably 0.43 or less, and more preferably 0.40 or less.

In the present invention, by setting the relationship between the thickness of the first surface adhesive layer, the thickness of the intermediate resin layer, and the thickness of the second surface adhesive layer within the above-mentioned condition range, the step followability can be improved more effectively. Furthermore, by setting the relationship between the thicknesses of the layers within the above-mentioned condition range, the reworkability of the laminated adhesive sheet can also be improved. The so-called high reworkability of the laminated adhesive sheet means that the laminated adhesive sheet can be peeled from the adherend without residue if necessary, and the laminated adhesive sheet does not break during the peeling process.

The value of A / C is preferably 0.25 or more and 4.0 or less, more preferably 0.65 or more and 1.5 or less, and even more preferably 0.9 or more and 1.1 or less. The thickness (A) of the first surface adhesive layer is particularly preferably the same as the thickness (C) of the second surface adhesive layer.

The overall thickness of the laminated adhesive sheet of the present invention is preferably 10 μm or more, more preferably 30 μm or more, and still more preferably 50 μm or more. The overall thickness of the laminated adhesive sheet is preferably 1,000 μm or more, more preferably 700 μm or less, and even more preferably 500 μm or less.

The thickness (A) of the first surface adhesive layer is preferably 5 μm or more, and more preferably 10 μm or more. The thickness (A) of the first surface adhesive layer is preferably 50 μm or less, and more preferably 45 μm or less.

The thickness (C) of the second surface adhesive layer is preferably 5 μm or more, and more preferably 10 μm or more. The thickness (C) of the second surface adhesive layer is preferably 50 μm or less, and more preferably 45 μm or less.

The thickness (B) of the intermediate resin layer is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. The thickness (B) of the intermediate resin layer is preferably 500 μm or less, more preferably 300 μm or less, and still more preferably 200 μm or less.

The dynamic storage elasticity coefficient G 'of the first surface adhesive layer and the second surface adhesive layer at 25 ° C at a frequency of 1 Hz is preferably 3 × 10 ⁴ Pa or more and 3 × 10 ⁵ Pa or less, and more preferably 9 × 10 ⁴ Pa or more and 3 × 10 ⁵ Pa or less, and more preferably 1 × 10 ⁵ Pa or more and 2 × 10 ⁵ Pa or less. The dynamic storage elasticity coefficient G ′ of the first surface adhesive layer and the second surface adhesive layer at 80 ° C. at a frequency of 1 Hz is preferably 5 × 10 ³ Pa or more and 5 × 10 ⁴ Pa or less, more preferably 9 × 10 ³ Pa or more and 5 × 10 ⁴ Pa or less, and more preferably 1 × 10 ⁴ Pa or more and 4 × 10 ⁴ Pa or less.

The dynamic storage elasticity coefficient G ′ of the intermediate resin layer at a frequency of 1 Hz at 25 ° C. is preferably 7 × 10 ⁴ Pa or more and 7 × 10 ⁵ Pa or less, more preferably 1 × 10 ⁵ Pa or more and 7 × 10 ⁵ Pa or less, Still more preferably, it is 1 × 10 ⁵ Pa or more and 4 × 10 ⁵ Pa or less. The dynamic storage elasticity coefficient G ′ of the intermediate resin layer at a frequency of 1 Hz at 80 ° C. is preferably 1 × 10 ⁴ Pa or more and 1 × 10 ⁵ Pa or less, more preferably 5 × 10 ⁴ Pa or more and 1 × 10 ⁵ Pa Hereinafter, it is more preferably 5 × 10 ⁴ Pa or more and 7 × 10 ⁴ Pa or less.

The dynamic storage elasticity coefficient G 'of the laminated adhesive sheet at 25 ° C and a frequency of 1 Hz is preferably 3 × 10 ⁴ Pa or more and 3 × 10 ⁵ Pa or less, more preferably 9 × 10 ⁴ Pa or more and 3 × 10 ⁵ Pa or less, Still more preferably, it is 1 × 10 ⁵ Pa or more and 2 × 10 ⁵ Pa or less. The dynamic storage elasticity coefficient G ′ at a frequency of 1 Hz at 80 ° C. is preferably 5 × 10 ³ Pa or more and 5 × 10 ⁴ Pa or less, more preferably 9 × 10 ³ Pa or more and 5 × 10 ⁴ Pa or less, and More preferably, it is 1 × 10 ⁴ Pa or more and 4 × 10 ⁴ Pa or less. The dynamic storage elastic coefficient of the above-mentioned laminated adhesive sheet is obtained by punching the obtained laminated adhesive sheet (the first surface adhesive layer, the intermediate resin layer and the second surface adhesive layer) to 10 mm × 8 mm. The fixed shear method of the viscoelastic device (trade name: Rheogel-E4000) was measured with a jig. The measurement conditions were set at a frequency of 1 Hz and a heating rate of 2 ° C./min, and the temperature was measured at 25 ° C. and 80 ° C. within a range of 0 ° C. to 100 ° C. when the temperature was raised at a step temperature of 1 ° C.

The value of the loss tangent tanδ of the dynamic shear viscoelasticity coefficient of the laminated adhesive sheet of the present invention at a measurement temperature of 25 ° C and a frequency of 1 Hz is preferably 0.56 or more and 0.75 or less, more preferably 0.58 or more and 0.70 or less, and even more preferably 0.59 or more and 0.68 or less. By setting the value of the loss tangent tan δ of the laminated adhesive sheet to be within the above range, the followability of the step difference of the laminated adhesive sheet can be further improved. By setting the dynamic storage elasticity coefficient G 'of the laminated adhesive sheet within the above range, better follow-up of the step difference can be obtained, but by dividing the value of the dynamic storage elasticity coefficient G' by the loss elasticity coefficient G " The loss tangent tan δ is set to be in the above range, and more excellent followability of the step can be obtained.

The value of the loss tangent tanδ of the dynamic shear viscoelasticity coefficient of the laminated adhesive sheet of the present invention at a measurement temperature of 80 ° C and a frequency of 1 Hz is preferably 0.50 or more and 0.80 or less, more preferably 0.50 or more and 0.70 or less, and even more preferably 0.50 to 0.65. By setting the value of tan δ of the laminated adhesive sheet within the above range, the durability and quality stability of the laminated adhesive sheet after bonding can be further improved.

In the laminated adhesive sheet of the present invention, the value of the loss tangent tanδ of the dynamic shear viscoelasticity coefficient at a measurement temperature of 80 ° C and a frequency of 1Hz after the ultraviolet light is irradiated in such a manner that the accumulated light amount becomes 2000 mJ / cm ² is preferably more than the ultraviolet radiation. Before low. Specifically, the value of the loss tangent tanδ of the dynamic shear viscoelastic coefficient at a measurement temperature of 80 ° C. and a frequency of 1 Hz after ultraviolet irradiation is preferably 0.60 or less, more preferably 0.55 or less, and still more preferably 0.50 or less.

Each surface of the first surface adhesive layer and the second surface adhesive layer is preferably covered with a release sheet. That is, the present invention relates to a laminated adhesive sheet having a release sheet.

Examples of the release sheet include: a release sheet substrate, a release laminate sheet having a release agent layer provided on one side of the release sheet substrate, and a polyethylene film or polypropylene as a low-polarity substrate. Polyolefin films such as films.

As the base material for a release sheet in the release laminated sheet, paper or a polymer film can be used. As the release agent system constituting the release agent layer, for example, a general-purpose addition or condensation type silicone release agent or a compound containing a long-chain alkyl group can be used. Particularly preferred is the use of a highly reactive additive silicone release agent.

Specific examples of the silicone release agent include: BY24-4527, SD-7220, etc. manufactured by Toray Dow Corning Silicone; or KS-3600, KS-774, X62-2600, manufactured by Shin-Etsu Chemical Industry Co., Ltd. Wait. In addition, it is preferable that the polysiloxane-based release agent contains an organic silicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units, or CH ₂ = CH (CH ₃ ) SiO _1/2 units. Silicone resin. Specific examples of the silicone resin include BY24-843, SD-7292, and SHR-1404 manufactured by Toray Dow Corning Silicone, or KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Industry Co., Ltd.

In the peeling sheet laminated | stacked on each surface of a 1st surface adhesive layer and a 2nd surface adhesive layer, it is preferable to set it as the thing whose peelability differs. If the releasability of one of them is different from the releasability of the other, it is preferable that only a release sheet having a higher releasability can be easily detached first, which is preferable.

The adhesive force of the first surface adhesive layer of the laminated adhesive sheet of the present invention is preferably 25N / 25mm or more, and more preferably 30N / 25mm or more. The adhesive force of the second surface adhesive layer of the laminated adhesive sheet is preferably 25 N / 25 mm or more, and more preferably 30 N / 25 mm or more. The above-mentioned adhesive force is an adhesive force after the laminated adhesive sheet is pasted to the adherend, and then the active energy ray is further irradiated (after completely hardened). The adhesion force of the above-mentioned surface adhesive layer to the adherend is determined by pulling and peeling the adherend at 180 ° according to JIS Z 0237.

The laminated adhesive sheet of the present invention preferably has a haze value (value measured according to JIS K 7136: 2000) of 23 ° C and a relative humidity of 50%, which is 2% or less, more preferably 1.5% or less, and even more preferably 1%. the following. When the haze value is within the above range, the transparency required when the laminated adhesive sheet is used for an optical member can be satisfied. When the haze value is 2% or less, it is suitable for optical applications.

The laminated adhesive sheet of the present invention preferably has a total light transmittance (value measured in accordance with JIS K 7361-1: 1997) of 80% or more, more preferably 90% or more under an environment of 23 ° C and a relative humidity of 50%. When the total light transmittance is within the above range, the transparency is high and it is suitable for optical applications.

    (Intermediate resin layer)    

The laminated adhesive sheet of the present invention has an intermediate resin layer as a support. Examples of the intermediate resin layer include acrylic resin, urethane-acrylic copolymer, styrene-acrylic copolymer, polystyrene, polyethylene terephthalate, polycarbonate, and polyetheretherketone. , Triethylfluorinated cellulose and other films. Among them, a film containing an acrylic resin or a urethane-acrylic copolymer is preferably used as the intermediate resin layer.

The intermediate resin layer may be a solvent-based resin layer or a solvent-free resin layer. The solvent-based resin layer is formed by coating a resin composition containing a solvent and volatilizing the solvent by steps such as heating and drying. The solventless resin layer is formed by coating a resin composition containing substantially no solvent, and curing the resin composition. The resin composition containing substantially no solvent means that the content of the solvent is 1% by mass or less based on the total mass of the resin composition.

The solvent used when forming the solvent-based resin layer is used to improve the coating suitability of the adhesive composition. The solvent is preferably a solvent having no polymerizable unsaturated group. When the surface adhesive layer contains a photopolymerization initiator, a solvent having a higher vapor pressure at 25 ° C than the photopolymerization initiator is preferred. The larger the vapor pressure difference is, the fewer the coating defects are, and the easier the production is, the vapor pressure of the solvent is preferably 2000 Pa or more, and particularly preferably 5000 Pa or more. The upper limit is not particularly limited, but is practically preferably 50,000 Pa or less.

    (Surface Adhesive Layer)    

The laminated adhesive sheet of the present invention contains a surface adhesive layer on both surfaces. In this specification, the surface adhesive layer on one side of the intermediate resin layer is referred to as a first surface adhesive layer, and the surface adhesive layer on the other side of the intermediate resin layer is referred to as a second surface adhesive layer. The first surface adhesive layer and the second surface adhesive layer may also be the same layer, and this structure is a preferable aspect.

In the following description, the first surface adhesive layer and the second surface adhesive layer are the same layer, and are collectively referred to as a "surface adhesive layer" for explanation.

The surface adhesive layer is a solvent-based adhesive layer containing a (meth) acrylate copolymer (A) and a dehydrogenated photopolymerization initiator (B). The surface adhesive layer is obtained by hardening an adhesive composition containing a solvent. That is, the adhesive composition forming the surface adhesive layer contains a (meth) acrylate copolymer (A), a dehydrogenated photopolymerization initiator (B), and a solvent (C).

    <(Meth) acrylate polymer (A)>    

The (meth) acrylate polymer (A) may be a polymer composed of only a non-crosslinkable (meth) acrylate unit (a1). However, the (meth) acrylate polymer (A) preferably contains a non-crosslinkable (meth) acrylic acid in order to easily adjust the glass transition temperature (Tg) to a desired range and to easily control the physical properties of the adhesive sheet. A (meth) acrylic acid ester copolymer of an ester unit (a1) and a (meth) acrylic monomer unit (a2) having a crosslinkable functional group. In this specification, "unit" means a repeating unit (monomer unit) constituting a polymer.

The (meth) acrylate copolymer (A) preferably has transparency to such an extent that the visibility of the display device is reduced.

The weight average molecular weight of the (meth) acrylate polymer (A) is preferably 100,000 or more, more preferably 200,000 or more, and still more preferably 300,000 or more. The weight average molecular weight of the (meth) acrylate polymer (A) is preferably 2 million or less, may be 1.5 million or less, and may be less than 1 million. By setting the weight average molecular weight within the above range, the surface adhesive layer can be made into a semi-hardened state, and sufficient adhesion or durability can be ensured. In addition, by using a (meth) acrylate polymer (A) having a larger weight average molecular weight in combination, the heat resistance or durability of the surface adhesive layer can be improved.

The weight average molecular weight of the (meth) acrylate polymer (A) is measured by gel permeation chromatography (GPC), and is a value determined on the basis of polystyrene. The measurement conditions of gel permeation chromatography (GPC) are as follows.

Solvent: Tetrahydrofuran

Columns: Shodex KF801, KF803L, KF800L, KF800D (use 4 connected Showa Denko Corporation)

Column temperature: 40 ℃

Sample concentration: 0.5% by mass

Detector: RI-2031plus (manufactured by JASCO)

Pump: RI-2080plus (manufactured by JASCO)

Flow (flow rate): 0.8ml / min

Injection volume: 10 μl

Standard curve: A standard curve obtained using 10 samples of standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko Corporation) Mw = 1320-2,500,000.

The content of the (meth) acrylate polymer (A) is relative to the total mass of the adhesive composition forming the surface adhesive layer, and is preferably 75% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass. %the above.

    <Non-crosslinkable (meth) acrylate unit (a1)>    

The non-crosslinkable (meth) acrylate unit (a1) is preferably derived from a repeating unit of an alkyl (meth) acrylate having an alkyl group, and more preferably is derived from an (meth) acrylic acid alkyl group having a branched alkyl group. Repeating unit of a base ester. When the non-crosslinkable (meth) acrylate unit (a1) has an alkyl group, the number of alkyl carbons is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, and even more preferably 3 or more. It is 10 or less, and more preferably 3 or more and 9 or less.

Examples of such an alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (methyl) Base) n-butyl acrylate, isobutyl (meth) acrylate, third butyl (meth) acrylate, n-amyl (meth) acrylate, iso-amyl (meth) acrylate, n-hexyl (meth) acrylate Ester, isohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isoheptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, N-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, iso-decyl (meth) acrylate, n-undecyl (meth) acrylate, (meth) N-dodecyl acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) Benzyl acrylate and the like. These may be used alone or in combination of two or more. Among them, as the non-crosslinkable (meth) acrylate unit, n-butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferably used.

The content of the unit (a1) derived from the non-crosslinkable (meth) acrylate in the (meth) acrylate polymer (A) is based on the total mass of the (meth) acrylate polymer (A), It is preferably at least 40% by mass, more preferably at least 50% by mass, and even more preferably at least 60% by mass. The content of the unit (a1) is preferably 90% by mass or less, and more preferably 85% by mass or less.

    <(Meth) acrylic monomer unit (a2) having a crosslinkable functional group>    

Examples of the (meth) acrylic monomer unit (a2) having a crosslinkable functional group include a monomer unit containing a hydroxyl group, a monomer unit containing an amine group, a monomer unit containing an epoxy group, and Carboxyl monomer unit. These monomer units may be one type or two or more types.

The hydroxyl-containing monomer unit is a repeating unit derived from a hydroxyl-containing monomer. Examples of the hydroxyl-containing monomer include (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. Hydroxyalkyl esters; (meth) acrylic acid [(mono, di, or poly) alkylene glycols], such as mono (diethylene glycol) (meth) acrylates; monocaprolactone (meth) acrylates, etc. ( (Meth) acrylate.

The amine group-containing monomer unit may be, for example, a repeating unit derived from an amine group-containing monomer such as (meth) acrylamidoamine or allylamine.

Examples of the glycidyl group-containing monomer unit include repeating units derived from a glycidyl group-containing monomer such as glycidyl (meth) acrylate.

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

The content of the (meth) acrylic monomer unit (a2) having a crosslinkable functional group in the (meth) acrylate polymer (A) is relative to that of the (meth) acrylate polymer (A). The total mass is preferably 0.01% by mass or more, and more preferably 0.5% by mass or more. The content of the unit (a2) is preferably 40% by mass or less, and more preferably 35% by mass or less.

    <Other monomer units>    

The (meth) acrylate polymer (A) may optionally have a non-crosslinkable (meth) acrylate unit (a1) and a (meth) acrylic monomer unit (a2) having a crosslinkable functional group. ). Other monomers may be those that can be copolymerized with a non-crosslinkable (meth) acrylate and an acrylic monomer having a crosslinkable functional group, and examples thereof include (meth) acrylonitrile and vinyl acetate. Esters, styrene, vinyl chloride, vinyl pyrrolidone, vinyl pyridine and the like.

The content of other monomer units is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

    <Dehydrogenated photopolymerization initiator (B)>    

The dehydrogenation type photopolymerization initiator (B) is a starter of a polymerization reaction of the (meth) acrylate copolymer (A) by irradiation with active energy rays. Examples of the dehydrogenation-type photopolymerization initiator include diphenyl ketone, benzamyl benzoic acid, methyl benzamyl benzoate, 4-phenyldiphenyl ketone, hydroxydiphenyl ketone, 3 , 3'-dimethyl-4-methoxydiphenyl ketone, 2,4,6-trimethyldiphenyl ketone, 4-methyldiphenyl ketone, 9-oxysulfur , 2-chloro9-oxysulfur 2-methyl 9-oxysulfur 2,4-dimethyl 9-oxosulfur Isopropyl 9-oxysulfur , Camphorquinone, dibenzocycloheptanone, 2-ethylanthrone, 3,3 ', 4,4'-tetrakis (third butylperoxycarbonyl) diphenyl ketone, benzyl, 9,10- Phenanthrenequinone and so on. Among them, the dehydrogenation type photopolymerization initiator (B) preferably contains at least 1 selected from the group consisting of diphenyl ketone, 4-methyldiphenyl ketone, and 2,4,6-trimethyldiphenyl ketone. Species, more preferably containing 4-methyldiphenyl ketone.

The content of the dehydrogenated photopolymerization initiator in the adhesive composition forming the adhesive layer in the first surface adhesive layer and the second surface adhesive layer is relative to the (meth) acrylate polymer (A) 100 parts by mass, preferably 0.5 parts by mass or more and 10.0 parts by mass or less, more preferably 0.5 parts by mass or more and 7.0 parts by mass or less, still more preferably 0.5 parts by mass or more and 5.0 parts by mass or less.

In the present invention, a polymerization initiator other than the above-mentioned dehydrogenation type photopolymerization initiator is preferably 0.1 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate polymer (A), and more preferably It does not contain substantially. That is, in the present invention, it is preferred to use a dehydrogenation type photopolymerization initiator as the polymerization initiator alone.

Since the dehydrogenation type photopolymerization initiator can also be used as a repeating reaction initiator by light irradiation, it can also cause post-curing to the adhesive sheet of the present invention.

    <Solvent (C)>    

The adhesive composition system contains a solvent (C). That is, the surface adhesive layer of the present invention is formed by applying a solvent-based adhesive composition and evaporating the solvent.

Examples of the solvent (C) include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; methylene chloride, trichloroethane, and trichloromethane. Halogenated hydrocarbons such as vinyl chloride, tetrachloroethylene, and dichloropropane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and diacetone alcohol; diethyl ether, diisopropyl ether, and two Ethers such as alkane, tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone; methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, Polyesters such as ethyl butyrate; glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, and the like derivative.

The solvent (C) may be used singly or in combination of two or more kinds. The content of the solvent (C) in the adhesive composition is not particularly limited, and may be 25 mass parts or more and 500 mass parts or less based on 100 mass parts of the (meth) acrylate copolymer (A). It is 30 mass parts or more and 400 mass parts or less.

The content of the solvent (C) is 10% by mass or more and 90% by mass or less with respect to the total mass of the adhesive composition, and may be 20% by mass or more and 80% by mass or less.

    <Other ingredients>    

The content of the crosslinking agent in the adhesive composition is preferably 0.01 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate copolymer (A). That is, it is preferable that the adhesive composition is substantially free of a crosslinking agent. As the crosslinking agent, isocyanate compounds, epoxy compounds, A well-known crosslinking agent such as an oxazoline compound, an aziridine compound, a metal chelate compound, a butylated melamine compound, etc. is not intentionally added to the adhesive composition.

The above-mentioned content of the cross-linking agent is the same as that in the surface adhesive layer of the laminated adhesive sheet. That is, the content of the cross-linking agent in the first surface adhesive layer is preferably 0.01 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate copolymer (A); in the second surface adhesive layer The content of the crosslinking agent is preferably 0.01 parts by mass or less based on 100 parts by mass of the (meth) acrylate copolymer (A).

The adhesive composition is within a range that does not impair the effect of the present invention, and may contain other components than the above. As other components, if necessary, it can select from well-known components as an additive for adhesives, for example, an antioxidant, a metal corrosion inhibitor, a tackifier, a silane coupling agent, an ultraviolet absorber, etc.

Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. These antioxidants may be used individually by 1 type, and may use 2 or more types together.

Examples of the metal corrosion preventing agent include benzotriazole-based resins.

Examples of the tackifier system include turpentine resin, terpene resin, terpene phenol resin, coumarone-indene resin, styrene resin, xylene resin, phenol resin, and petroleum resin.

Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto-substituted alkoxy oligomer).

Examples of the ultraviolet absorber include benzotriazole-based compounds, diphenylketone-based compounds, and hindered amine-based compounds. Among them, when the active energy ray at the time of curing is a case where ultraviolet rays are used, it must be added within a range that does not hinder the polymerization reaction.

Furthermore, the adhesive composition may contain a plasticizer. As the plasticizer, a non-functional acrylic polymer can be used. The "non-functional acrylic polymer" refers to a polymer composed of only acrylic monomer units having no functional group other than an acrylate group, or an acrylic monomer having no functional group other than an acrylate group. A unit composed of a unit and a non-acrylic monomer unit having no functional group.

As an acrylic monomer unit which does not have a functional group other than an acrylate group, the thing similar to the non-crosslinkable (meth) acrylate unit (a1) is mentioned, for example.

Examples of non-acrylic monomer units having no functional group include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, and myristic acid. Vinyl esters, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl carboxylates such as vinyl benzoate, or styrene.

    (Manufacturing method of laminated adhesive sheet)    

The manufacturing method of the laminated adhesive sheet of the present invention includes applying the above-mentioned adhesive composition on both sides of the intermediate resin layer, or separately forming each of the above-mentioned layers, and then sequentially laminating / attaching these layers. Then, a step of semi-hardening (primary hardening) by irradiating active energy rays. Alternatively, the method for manufacturing a laminated adhesive sheet of the present invention may further include: coating an adhesive composition for a first surface adhesive layer on a first release sheet, and semi-hardening (primary curing) by irradiation with active energy rays. A step of applying an adhesive composition for a second surface adhesive layer on the second release sheet, and semi-hardening (primary hardening) by irradiation with active energy rays; and including each surface thus obtained A step of bonding the adhesive layer to the intermediate resin layer.

In any method, after the adhesive composition is applied, it is preferable to provide a heating and drying step in order to volatilize the solvent (C). The coating thus obtained is irradiated with active energy rays to become a semi-hardened material (surface adhesive layer).

The application of the 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 rod coater, a gravure coater, a microgravure coater, a rod leaf coater, a lip coater, Die coating machine, shower coating machine, etc.

The heating and drying step of the coating film can be performed using a known heating device such as a heating furnace or an infrared lamp. For example, drying is performed in an air-circulating thermostatic oven at a temperature of 50 ° C. to 150 ° C. for 10 seconds to 10 minutes.

In the step of irradiating the coating film with active energy rays, examples of the active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Among them, it is preferable to use ultraviolet rays or electron beams as the active energy rays, and it is more preferable to use ultraviolet rays. 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, or the like can be used. As the electron beam, for example, a Cockroft-Walton type, a Van-de-Graaff type, a resonant transformer type, an insulated core transformer type, a linear type, Electron beams emitted by various electron beam accelerators such as Dynamitron type and high frequency type.

The irradiation output of ultraviolet rays is preferably such that the accumulated light amount is 100 mJ / cm ² or more and 20,000 mJ / cm ² or less, and more preferably 500 mJ / cm ² or more and 15000 mJ / cm ² or less. In addition, 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.

    (How to use laminated adhesive sheet)    

In the method for using the laminated adhesive sheet of the present invention, at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet is brought into contact with the surface of the adherend, and active energy rays are radiated in this state. Harden the surface adhesive layer. This hardening step is preferably a step of completely hardening the surface adhesive layer. Moreover, in the method of using the laminated adhesive sheet of the present invention, it is preferable that both the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet are brought into contact with the surface of the adherend, respectively, and the activity is irradiated in this state. Energy rays harden the surface adhesive layer.

Before the irradiation of active energy rays, the surface adhesive layer of the laminated adhesive sheet is in a semi-hardened state, so even if the adherend has a stepped portion, the surface adhesive layer can follow its unevenness. In this way, after the laminated adhesive sheet is attached to follow the unevenness, the surface adhesive layer is completely hardened by active energy rays, thereby improving the cohesive force of the surface adhesive layer and the adhesion to the adherend. In addition, the durability of the adhesive can be improved.

Examples of the active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Among these, from the viewpoint of versatility, ultraviolet rays, electron beams, and particularly preferred ultraviolet rays are preferred.

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, or the like can be used.

As the electron beam, for example, a Cockroft-Walton type, a Van-de-Graaff type, a resonant transformer type, an insulated core transformer type, a linear type, Electron beams emitted by various electron beam accelerators such as Dynamitron type and high frequency type.

    (Laminated body)    

The present invention relates to a laminate having an adherend on at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet. The laminated body of the present invention is preferably one having an adherend on both of the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet. The laminated system of the present invention is obtained by the steps of bringing the surface adhesive layer of the laminated adhesive sheet into contact with the surface of the adherend, and irradiating active energy rays in this state to completely harden the adhesive layer.

The adherend is preferably an optical member. Examples of the optical member include each constituent member in an optical product such as a touch panel or an image display device. As a constituent member 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, and a transparent conductive film coated with a conductive polymer Film, hard coating film, fingerprint resistant film, etc. As a constituent member of the image display device, for example, an anti-reflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device can be mentioned.

Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, and triethylpyrene. Cellulose, polyimide, cellulose halide and the like.

The laminated adhesive sheet of the present invention can be used for bonding two adherends. At this time, the laminated adhesive sheet of the present invention is used for the bonding of ITO films inside the touch panel, the bonding of ITO film and ITO glass, the bonding of ITO film of touch panel and liquid crystal panel, protective glass and ITO. Lamination of films, lamination of protective glass and decorative glass, etc.

    (Manufacturing method of laminated body)    

The invention also relates to a method for manufacturing a laminated body. The manufacturing method of the laminated body of the present invention includes contacting at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet to the surface of the adherend, and irradiating active energy rays to make the surface in this state. Step of hardening the adhesive layer. This hardening step is preferably a step of completely hardening the surface adhesive layer. Further, in the method for manufacturing a laminated body of the present invention, it is preferable that both the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet are brought into contact with the surface of the adherend, respectively, and active energy is radiated in this state. The radiation hardens the surface adhesive layer.

Examples of the active energy ray include the aforementioned energy ray, preferably ultraviolet rays or electron beams, and particularly preferably ultraviolet rays.

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

In the method for manufacturing a laminated body according to the present invention, the surface adhesive layer of the laminated adhesive sheet is an adhesive layer before it is hardened formally, and is further an adhesive layer having a space where active energy rays harden, so even if the adherend has a stepped portion The surface adhesive layer can follow its unevenness. In this way, after the laminated adhesive sheet is adhered to follow the unevenness, the surface adhesive layer is completely hardened by active energy rays, thereby improving the cohesive force of the surface adhesive layer and the adhesion to the adherend. In addition, the durability of the adhesive can be improved.

    [Example]    

Examples and comparative examples are listed below to describe the features of the present invention in more detail. The materials, usage amounts, proportions, processing contents, processing orders, etc. 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 limited by the specific examples shown below.

    <Synthesis of Polymer A>    

To a reaction vessel including a cooling pipe, a nitrogen introduction pipe, a stirrer, and a thermometer, 80 parts by mass of ethyl acetate was added, and 75 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of vinyl acetate, and acrylic acid were added as monomers. 5 parts by mass. After the temperature was raised to 55 ° C. in the reaction vessel, the entire amount of a solution in which 0.06 parts by mass of azobisisobutyronitrile was dissolved in 10 parts by mass of ethyl acetate was added. Thereafter, the mixture was stirred while maintaining the temperature, and after stirring for 12 hours, it was cooled to stop the polymerization reaction. The polystyrene-equivalent weight average molecular weight Mw of the obtained acrylic copolymer obtained by GPC was 250,000.

    <Synthesis of Polymer B>    

To a reaction vessel including a cooling tube, a nitrogen introduction tube, a stirrer, and a thermometer, 170 parts by mass of 2-ethylhexyl acrylate, 8 parts by mass of vinyl acetate, and 12 parts by mass of acrylic acid were added. After the temperature was raised to 55 ° C in the reaction vessel, the entire amount of a solution in which 0.06 parts by mass of azobisisobutyronitrile was dissolved in 10 parts by mass of 2-ethylhexyl acrylate was added. Thereafter, the mixture was stirred while maintaining the temperature. After stirring for 6 hours, the mixture was cooled to stop the polymerization reaction. The polystyrene-equivalent weight average molecular weight Mw of the obtained acrylic copolymer obtained by GPC was 520,000, and the solid content concentration was 50% by mass.

    <Synthesis of Polymer C>    

To a reaction vessel including a cooling pipe, a nitrogen introduction pipe, a stirrer, and a thermometer, 465.9 parts by mass of polytetramethylene glycol (weight average molecular weight 1000), 9.6 parts by mass of 2-ethylhexyl acrylate, and 2,6- 1.7 parts by mass of tertiary butyl p-cresol and 0.3 parts by mass of p-methoxyphenol. After heating up until the temperature in the reaction container became 40 ° C, 101.5 parts by mass of isophorone diisocyanate was added. Next, 0.06 parts by mass of dioctyltin dineodecanoate was added, and the temperature was raised to 80 ° C. over 1 hour. Thereafter, it was held at 80 ° C. for 12 hours, and after confirming that all isocyanate groups had disappeared, it was cooled to obtain a urethane acrylate resin. The equivalent weight of the obtained urethane acrylate resin-based acrylic group was 7000, and the weight average molecular weight Mw of polystyrene conversion obtained by GPC was 18,000.

With respect to 100 parts by mass of the obtained urethane acrylate resin, 30 parts by mass of 2-ethylhexyl acrylate and acrylic acryloyl group were added at a container temperature of 80 ° C. 30 parts by mass of morpholine, stir until homogeneous. Thereafter, a 200-mesh metal mesh was used for filtration to obtain a polymer C.

    <Synthesis of Polymer D>    

First, the base polymer α is produced by solution polymerization in ethyl acetate. Specifically, a solution prepared by 2-ethylhexyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate at a mass ratio of 7: 2: 1 was prepared and used as a radical The 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was dissolved in the solution. The solution was heated to 60 ° C to perform random copolymerization to obtain a polymer D. The solution viscosity of the 45 mass% solution of polymer D at 23 ° C. was 5500 mPa · s.

    (Example 1)         [Preparation of Adhesive Solution]    

With respect to 100 parts by mass of the solid content of the polymer A obtained as described above, 1 part by mass of a dehydrogenation-type photopolymerization initiator (4MBP (4-methyldiphenyl ketone)) was added, and the solid form was diluted by ethyl acetate and stirred. A solution having a concentration of 40% by mass is used to prepare an adhesive composition.

    [Production of intermediate resin layer]    

0.5 mass part of 1-hydroxy-cyclohexyl-phenyl-one (BASF JAPAN (stock), IRGACURE184) was further added with respect to 100 mass parts of solid parts of the polymer C obtained above, and the solution for intermediate resin layers was prepared. On one release-treated polyethylene terephthalate film (manufactured by Teijin DuPont Film Co., Ltd.), the solution for the intermediate resin layer was applied so that the thickness of the cured adhesive sheet became 105 μm, and It was held by another release-treated polyethylene terephthalate film (made by Teijin DuPont Film). Via treatment of a polyester film was peeled off,, according to the cumulative amount of light of 365nm becomes 1,000mJ / cm ² of the embodiment by means of ultraviolet irradiator (EYE GRAPHICS (stocks in accordance with the degree of 2mW / cm ² irradiated with actinic light from the one surface side of 30 seconds) (ECS-301G1) was irradiated with ultraviolet rays to produce an intermediate resin layer. The cumulative light amount at 365 nm was measured using UVPF-A1 (manufactured by EYE GRAPHICS).

    [Production of laminated adhesive sheet]    

The adhesive composition obtained above was coated on a release-treated polyethylene terephthalate film (manufactured by Teijin DuPont Film Co., Ltd.) using a doctor blade YD type (manufactured by YOSHIMITSU Seiki Co., Ltd.). The cloth was heated by a dryer at 80 ° C for 3 minutes. In this way, a first surface adhesive layer having a thickness of 35 μm was prepared. In the same manner, a second surface adhesive layer having a thickness of 35 μm was produced. Any of the release-treated polyethylene terephthalate films laminated on the front and back surfaces of the intermediate resin layer obtained as described above is peeled off, and the laminating machine and the adhesive surface of the first surface adhesive layer are peeled off. Laminate. In addition, the other part of the release-treated polyethylene terephthalate film laminated on the surface of the intermediate resin layer was peeled off, and the laminating machine and the adhesive surface of the second surface adhesive layer were laminated. .

The polyethylene terephthalate film laminated during the production of the first surface adhesive layer and the second surface adhesive layer is produced by ultraviolet radiation (made by EYE GRAPHICS (stock), ECS, both sides of the surface, ECS -301G1) Irradiate ultraviolet rays so that the accumulated light amount becomes 2,000 mJ / cm ² to obtain the laminated adhesive sheet of Example 1 (total thickness 175 μm; first surface adhesive layer: intermediate resin layer: second surface adhesive layer = 35 μm : 105 μm: 35 μm).

    (Example 2)    

Except that the addition amount of the dehydrogenation-type photopolymerization initiator (4MBP) in the [Preparation of the Adhesive Solution] step was changed to 0.5 parts by mass, the same procedure as in Example 1 was performed to produce an adhesive composition and a laminated adhesive sheet.

    (Example 3)    

In addition to the [Adhesive Solution Preparation] step, the dehydrogenation type photopolymerization initiator (4MBP) was changed to a mixture of 4MBP and 2,4,6-trimethyldiphenyl ketone (manufactured by IGM (KK), TZT) Other than that, it carried out similarly to Example 1, and produced the adhesive composition and laminated adhesive sheet.

    (Example 4)    

An adhesive composition was produced in the same manner as in Example 1. Next, it carried out similarly to Example 1 except having changed the [intermediate resin layer] process as follows, and produced the laminated adhesive sheet.

    [Production of intermediate resin layer]    

To 100 parts by mass of polymer D, 10 parts by mass of isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) and 0.15 parts by mass of xylene diisocyanate compound (manufactured by Mitsui Chemicals Co., Ltd., D-110N) 1.0 part by mass of 1-hydroxy-cyclohexyl-phenyl-one (BASF JAPAN (stock), IRGACURE184), and ethyl acetate was added so that the solid content concentration became 40% by mass to obtain an adhesive composition.

The adhesive composition obtained as described above was used on a release-treated polyethylene terephthalate film (manufactured by Teijin DuPont Film Co., Ltd.) so that the thickness became 105 μm after drying, using a doctor blade YD type ( Coating was performed by YOSHIMITSU Seiki Co., Ltd., and heated at 80 ° C for 3 minutes by a dryer. The other exposed adhesive layer was bonded by another release-treated polyethylene terephthalate film (manufactured by Teijin DuPont Film Co., Ltd.). An intermediate resin layer was produced by irradiating an ultraviolet ray with an ultraviolet irradiator (manufactured by EYE GRAPHICS, Inc., ECS-301G1) so that the accumulated light amount of 365 nm became 1,500 mJ / cm ^{2 on} the front side. The cumulative light amount at 365 nm was measured using UVPF-A1 (manufactured by EYE GRAPHICS).

    (Example 5)    

An adhesive composition was produced in the same manner as in Example 1. A laminated adhesive sheet was produced in the same manner as in Example 1 except that the thickness of the intermediate resin layer was changed as shown in Table 1.

    (Example 6)    

An adhesive composition was produced in the same manner as in Example 1. A laminated adhesive sheet was produced in the same manner as in Example 1 except that the thicknesses of the surface adhesive layer and the intermediate resin layer were changed as shown in Table 1.

    (Comparative example 1)    

A laminated adhesive sheet was produced in the same manner as in Example 1 except that the dehydrogenation type photopolymerization initiator was not added in the step of [Adhesive Solution Preparation].

    (Comparative example 2)    

A laminated adhesive sheet was produced in the same manner as in Example 1 except that the polymer A was changed to the non-solvent type polymer B in the step of [Adhesive Solution Preparation].

    (Comparative example 3)    

The procedure was the same as in Example 1 except that the dehydrogenation type photopolymerization initiator was changed to 1-hydroxy-cyclohexyl-phenyl-one (BASF JAPAN (shares), IRGACURE184) in the step of [Adhesive Solution Preparation]. Proceed to make a laminated adhesive sheet.

    (Comparative Example 4)    

A laminated adhesive sheet was produced in the same manner as in Example 1 except that the dehydrogenation type photopolymerization initiator was changed to an isocyanate compound (L-55E) in the step of [Adhesive Solution Preparation].

    (Example 11)    

In addition to changing the addition amount of the dehydrogenation type photopolymerization initiator (4MBP) to 4 parts by mass in the step of [Adhesive Solution Preparation], and the cumulative light amount of the irradiated ultraviolet rays in [Production of Multilayer Adhesive Sheet] Except for 6000 mJ / cm ² , the rest was carried out in the same manner as in Example 1 to prepare an adhesive composition and a laminated adhesive sheet.

    (Example 12)    

In addition to changing the addition amount of the dehydrogenation type photopolymerization initiator (4MBP) to 4 parts by mass in the step of [Adhesive Solution Preparation], and the cumulative light amount of the irradiated ultraviolet rays in [Production of Multilayer Adhesive Sheet] Except for 9000 mJ / cm ² , the rest was carried out in the same manner as in Example 1 to produce an adhesive composition and a laminated adhesive sheet.

    (Example 13)    

In addition to changing the addition amount of the dehydrogenation type photopolymerization initiator (4MBP) to 4 parts by mass in the step of [Adhesive Solution Preparation], and the cumulative light amount of the irradiated ultraviolet rays in [Production of Multilayer Adhesive Sheet] Except for 2000 mJ / cm ² , the rest was carried out in the same manner as in Example 1 to prepare an adhesive composition and a laminated adhesive sheet.

    (Evaluation and analysis)         (Segment Followability (50 μm))    

UV-curable ink was screen-printed on the surface of glass plate A (120 mm in height × 70 mm in width × 0.7 mm in thickness) so that the coating thickness became 5 μm (inner edge size: 90 mm in length × 50 mm in width × width) 5mm). Next, the printed UV-curable ink is cured by irradiating ultraviolet rays. This step was repeated 10 times to obtain a printing step glass plate having a step difference of 50 μm.

The laminated adhesive sheets obtained in the examples and comparative examples were cut into a shape having a length of 94 mm × 54 mm, and the polyethylene terephthalate film laminated on the first surface adhesive layer side was peeled off, and a laminator was used (YOUBON Co., Ltd. Co., Ltd. (IKO-650EMT), so that the first surface adhesive layer covers and covers the entire frame-shaped printing surface of the printing step glass. Thereafter, the polyethylene terephthalate film laminated on the second surface adhesive layer side was peeled off, and the exposed second surface adhesive layer was laminated to the glass plate B (115 mm in height × 64 mm in thickness × width) by a laminator. 0.7 mm), and subjected to an autoclave treatment (40 ° C, 0.5 MPa, 30 minutes). Next, a laminated body was obtained by irradiating ultraviolet rays from a glass plate A side by an ultraviolet ray irradiator (manufactured by EYE GRAPHICS, Inc., ECS-301G1) so that the accumulated light amount became 2,000 mJ / cm ² .

The printing step difference portion of the laminated body was visually observed, and the followability of the step difference of the laminated adhesive sheet was evaluated according to the following criteria.

○: No foaming or peeling was observed at all.

△: Foaming, peeling, and the like are sometimes seen.

╳: Foaming or peeling was seen in each experiment.

    (Segment Followability (30 μm))    

UV-curable ink was screen-printed on the surface of glass plate A (120 mm in height × 70 mm in width × 0.7 mm in thickness) so that the coating thickness became 5 μm (inner edge size: 90 mm in length × 50 mm in width × width) 5mm). Next, the printed UV-curable ink is cured by irradiating ultraviolet rays. This step was repeated 6 times to obtain a printing step glass plate having a step difference of 30 μm. The rest are evaluated in accordance with the same method as (Segment Followability (50 μm)).

    (Heat resistance: Followability of step)    

The laminated body was treated at 85 ° C., 24 hours, or Heat Shock (one cycle was performed under conditions of 85 ° C. for 30 minutes and -40 ° C. for 30 minutes, and 48 cycles were performed).

After the treatment, the printed step difference of the laminated body was visually observed, and the heat resistance was evaluated according to the following criteria.

○: No foaming or peeling was observed at all.

Δ: Foaming or peeling was observed when the diameter was less than 0.5 mm.

╳: A plurality of foaming or peeling was seen, or one or more foaming or peeling with a diameter of 0.5 mm or more was seen.

    (Heat resistance: foreign body followability A)    

A 50 mm square polarizing plate (SKN-18243T, manufactured by Polatechno Co., Ltd.) was attached to the surface of glass plate C (76 mm in length × 52 mm in width × 1.0 mm in thickness). Then, the protective film of the polarizing plate was peeled off, and fine particles (NIKKA Co., Ltd., NIKKALYCO, average particle diameter: 25 μm) were uniformly distributed on the surface without particles overlapping.

The polyethylene terephthalate film laminated on the first surface adhesive layer side of the laminated adhesive sheet obtained in the examples and comparative examples was peeled off, and the first surface adhesive layer was bonded to the surface of the polarizing plate on which NIKKALYCO was dispersed. Then, an autoclave process was performed (40 ° C, 0.5 MPa, 30 minutes). Next, the polyethylene terephthalate film layer laminated on the second surface adhesive layer side is irradiated with an ultraviolet ray irradiator (manufactured by EYE GRAPHICS, Inc., ECS-301G1) so that the accumulated light amount becomes 2,000 mJ / cm ² A laminated body was obtained by irradiating ultraviolet rays.

The laminated body was treated at 85 ° C for 24 hours. After the treatment, the fine-particle dispersed portion of the laminate was visually observed, and the heat resistance was evaluated according to the following criteria.

○: No foaming or peeling was observed at all.

△: Fine foaming or peeling may be seen in some cases.

╳: Foaming or peeling was seen.

    (Durability: Foreign body followability B)    

Using the laminated adhesive sheet obtained in Examples 11 to 13, a laminated body was obtained by the same method as described in (Heat resistance: foreign body followability A). The laminated body was mounted on a QUV accelerated weathering tester (manufactured by Q-LAB), and ultraviolet radiation at a wavelength of 340 nm was irradiated at a radiation intensity of 0.63 W / m ² for 96 hours at a temperature of 60 ° C. to perform an acceleration treatment. After the accelerating treatment, the microparticle-dispersed portion of the laminate was visually observed, and the durability was evaluated according to the following criteria.

○: No foaming or peeling was observed at all.

△: Fine foaming or peeling may be seen in some cases.

╳: Foaming or peeling was seen.

    (Operability (presence or absence of leakage defects))    

The laminated adhesive sheets obtained in the examples and comparative examples were punched through a punching machine (Fuji Sangyo Precision Machinery Co., Ltd., UPD5000) to 120 mm in length × 55 mm in width, and then peeled off the laminated layer on the first surface adhesive layer A polyethylene terephthalate film is bonded to another release sheet (made by Teijin DuPont Film Co., Ltd.) having a peripheral edge portion increased by 10 mm. The polyethylene terephthalate film laminated on the second surface adhesive layer side of the above-mentioned bonded body was covered with a polyethylene terephthalate film having a length of 140 mm and a width of 80 mm and a further 100 g was placed thereon. The glass was treated with a dryer at 60 ° C for 100 hours. The adhesive exudation size of the peripheral portion of the bonded body was visually observed, and evaluated according to the following criteria.

○: No bleeding of the adhesive was observed.

(Triangle | delta): 0.1 mm of adhesive bleeding was seen.

╳: Seepage of adhesive more than 0.2 mm.

╳╳: See sticking to overlapping film

    (Adhesion)    

About the laminated adhesive sheet obtained by the Example and the comparative example, the adhesive force at the time of 180 degree pull-peeling of soda glass (made from Nippon Glass Glass) was measured in accordance with JIS Z 0237. The test piece was produced according to the following procedure. First, the polyethylene terephthalate film laminated on the first surface adhesive layer side was peeled off and bonded to an optical PET film having a thickness of 50 μm. Next, the polyethylene terephthalate film laminated on the second surface adhesive layer side was peeled off, and the soda glass was pressure-bonded by 2 kg. Thereafter, ultraviolet rays were irradiated from the side of the optical PET film by means of an ultraviolet irradiator so that the cumulative light amount became 2,000 mJ / cm ² , and left to stand for 24 hours at 23 ° C. and a relative humidity of 50% to prepare a test piece (25 mm × 50 mm in width). ).

    (Determination of dynamic storage elastic coefficient G ′ and tanδ)    

The dynamic storage elastic coefficient G 'and the dynamic shear viscoelastic coefficient loss tangent (tan δ) of the laminated adhesive sheet were measured using Rheogel-E4000 manufactured by UBM under the following conditions. The measurement is performed in a range of 0 ° C to 100 ° C at 25 ° C and / or 80 ° C. The tan δ after the additional UV irradiation was measured after the laminated adhesive sheet was irradiated with ultraviolet rays so that the accumulated light amount became 2000 mJ / cm ² .

Mode: solid shear

Strain: 2μm

Heating rate: 2 ℃ / min

Frequency: 1Hz

Thickness: 175μm

As can be seen from Table 1 and Table 2, in the examples, a laminated adhesive sheet excellent in step-following and heat resistance was obtained. On the other hand, the laminated pressure-sensitive adhesive sheet obtained in the comparative example did not take into account the step followability and heat resistance.

Claims (9)

    A laminated adhesive sheet has a first surface adhesive layer, an intermediate resin layer, and a second surface adhesive layer in this order. The first surface adhesive layer and the second surface adhesive layer each contain (methyl ) Solvent type adhesive layer of acrylate polymer (A) and dehydrogenated photopolymerization initiator (B).         For example, the laminated adhesive sheet according to claim 1, wherein the thickness of the first surface adhesive layer is A, the thickness of the intermediate resin layer is B, and the thickness of the second surface adhesive layer is C In this case, the value of A / B is 0.23 or more and 0.46 or less, and the value of C / B is 0.23 or more and 0.46 or less.         For example, if the laminated adhesive sheet of claim 1 or 2 is used, when the thickness of the first surface adhesive layer is A and the thickness of the second surface adhesive layer is C, the value of A / C is 0.25. Above and below 4.0.         For example, the laminated adhesive sheet of claim 1 or 2, wherein the (meth) acrylate copolymer (A) contained in the first surface adhesive layer and the second surface adhesive layer contains a carbon number of 1 A non-crosslinkable (meth) acrylate unit of an alkyl group of 10 or more and 10 or less.         For example, the laminated adhesive sheet of claim 1 or 2, wherein the dehydrogenated photopolymerization initiator (B) contained in the first surface adhesive layer and the second surface adhesive layer contains a compound selected from diphenyl At least one kind of ketone, 4-methyldiphenyl ketone, and 2,4,6-trimethyldiphenyl ketone.         For example, the laminated adhesive sheet of claim 1 or 2, wherein the content of the dehydrogenated photopolymerization initiator (B) in the adhesive composition forming the first surface adhesive layer is relative to the above (A) Base) 100 parts by mass of the acrylate copolymer (A) is 0.5 part by mass or more and 10.0 parts by mass or less; in the adhesive composition forming the second surface adhesive layer, the dehydrogenated photopolymerization initiator (B ) Content is 0.5 mass part or more and 10.0 mass parts or less with respect to 100 mass parts of said (meth) acrylate copolymer (A).         For example, the laminated adhesive sheet of claim 1 or 2, wherein the content of the crosslinking agent in the first surface adhesive layer is 0.01 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A). The content of the crosslinking agent in the second surface adhesive layer is 0.01 parts by mass or less based on 100 parts by mass of the (meth) acrylate copolymer (A).         A method for manufacturing a laminated body, comprising contacting at least one selected from a first surface adhesive layer and a second surface adhesive layer of the laminated adhesive sheet according to any one of claims 1 to 7, to a surface of an adherend, A step of curing the surface adhesive layer by irradiating active energy rays in this state.         A method for using a laminated adhesive sheet is to make at least one selected from the first surface adhesive layer and the second surface adhesive layer of the laminated adhesive sheet of any one of claims 1 to 7 contact the surface of an adherend, The surface adhesive layer is hardened by irradiating active energy rays in this state.