JP6745619B2 - Display body and method of manufacturing display body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a double-sided pressure-sensitive adhesive sheet suitable for laminating a display-member constituting member, a display body obtained by using the double-sided pressure-sensitive adhesive sheet, and a method for producing the same.

In recent years, various mobile electronic devices such as smartphones and tablet terminals have a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like. It is becoming more and more a touch panel. In the above display, a protective panel is usually provided on the front surface side of the display module.

Here, a gap is provided between the protective panel and the display module so that the deformed protective panel does not hit the display module even when the protective panel is deformed by an external force.

However, when the above-mentioned void, that is, the air layer is present, the reflection loss of light due to the difference in the refractive index between the protective panel and the air layer, and the difference in the refractive index between the air layer and the display module is large, and There is a problem that the image quality deteriorates.

Therefore, it has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, a frame-shaped printing layer may exist as a step on the display module side of the protective panel. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer floats in the vicinity of the step, which causes reflection loss of light. Therefore, the pressure-sensitive adhesive layer is required to have step followability.

In order to solve the above-mentioned problem, Patent Document 1 discloses that a shear storage elastic modulus (G′) at 25° C. and 1 Hz is 1.0 as an adhesive layer that fills a gap between a protective panel and a display module. Disclosed is a pressure-sensitive adhesive layer having a pressure of ×10 ⁵ Pa or less and a gel fraction of 40% or more.

JP, 2010-97070, A

In the invention disclosed in Patent Document 1, the step followability is improved by lowering the storage elastic modulus (G′) of the pressure-sensitive adhesive layer at room temperature. However, if the storage elastic modulus (G') at room temperature is lowered as described above, the film strength of the pressure-sensitive adhesive layer is lowered and the workability is deteriorated. For example, when the pressure-sensitive adhesive sheet is cut, the pressure-sensitive adhesive layer may be crushed and the pressure-sensitive adhesive may squeeze out on the cut surface, causing the pressure-sensitive adhesive to adhere to the blade.

The present invention has been made in view of such circumstances, and is a double-sided pressure-sensitive adhesive sheet that is excellent in step followability and has good processability, and a display body obtained by using the double-sided pressure-sensitive adhesive sheet, and a method for manufacturing the same. The purpose is to provide.

In order to achieve the above object, firstly, the present invention provides a first pressure-sensitive adhesive layer as an outer layer on one surface side, a second pressure-sensitive adhesive layer as an outer layer on the other surface side, and the first pressure-sensitive adhesive layer. And an intermediate layer located between the second adhesive layer, the glass transition temperature of the intermediate layer being 0°C or higher and 60°C or lower. A sheet is provided (Invention 1).

According to the above invention (Invention 1), since the glass transition temperature of the intermediate layer is within the above range, the intermediate layer becomes somewhat hard at room temperature, thereby improving the coating strength of the entire double-sided PSA sheet, The property becomes good. Further, when the glass transition temperature of the intermediate layer is within the above range, the intermediate layer is softened by heating, whereby the entire double-sided PSA sheet becomes excellent in flexibility and step followability.

In the said invention (invention 1), it is preferable that the said 1st adhesive layer and the 2nd adhesive layer are active energy ray curable (invention 2).

In the said invention (invention 1 and 2), it is preferable that the said intermediate|middle layer is active energy ray hardening (invention 3).

In the said invention (invention 3), it is preferable that the said intermediate|middle layer contains glass transition temperature 0 degreeC or more and 60 degrees C or less, and an active energy ray curable component (invention 4).

The Young's modulus of the double-sided pressure-sensitive adhesive sheet according to the above inventions (Inventions 1 to 4) is preferably 0.01 MPa or more and 100 MPa or less (Invention 5).

In the above inventions (Inventions 1 to 5), the ratio of the thickness of the intermediate layer to the total thickness of the first adhesive layer and the second adhesive layer is 0.05 or more and 2 or less. It is preferable (Invention 6).

The double-sided pressure-sensitive adhesive sheet according to the above inventions (Inventions 1 to 6) is used to bond one display body constituent member having a step on at least the surface on the side to be bonded and another display body constituent member. It is preferable (Invention 7).

Secondly, the present invention comprises two release sheets and the double-sided pressure-sensitive adhesive sheet (Invention 1 to 7) sandwiched between the release sheets so as to contact the release surfaces of the two release sheets. A double-sided pressure-sensitive adhesive sheet having a release sheet, which is a feature of the present invention (Invention 8).

Thirdly, the present invention relates to at least one display body constituent member having a step on at least a surface on the side to be bonded, another display body constituent member, the one display body constituent member, and the other display body constituent member. And a double-sided pressure-sensitive adhesive sheet (Invention 1 to 7) which is bonded to each other (Invention 9).

Fourthly, the present invention relates to one display member constituting member having at least a step on the surface to be bonded, another display member constituting member, the one display member constituting member and the other display member constituting member. And a cured double-sided pressure-sensitive adhesive sheet obtained by curing the above-mentioned double-sided pressure-sensitive adhesive sheet (Invention 2 and 3), which is bonded to each other (Invention 10).

Fifthly, the present invention produces a laminate comprising one display member and another display member via the double-sided pressure-sensitive adhesive sheets (Inventions 2 and 3). The double-sided pressure-sensitive adhesive sheet is irradiated with an active energy ray to cure the double-sided pressure-sensitive adhesive sheet, and a method for producing a display body is provided (Invention 11).

The double-sided pressure-sensitive adhesive sheet according to the present invention is excellent in step-following property and good in processability. Further, in the display body according to the present invention, the double-sided pressure-sensitive adhesive sheet having excellent step followability suppresses the formation of gaps, floats, and the like near the steps. Further, according to the method for manufacturing a display body of the present invention, it is possible to obtain a display body in which gaps, floats and the like are suppressed from being generated near the step.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the laminated body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Double-sided adhesive sheet]
A cross-sectional view of a double-sided PSA sheet according to an embodiment of the present invention is shown in FIG.
As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 2 according to the present embodiment has a first pressure-sensitive adhesive layer 21 as an outer layer on one surface side and a second pressure-sensitive adhesive layer 22 as an outer layer on the other surface side. And an intermediate layer 23 located between the first adhesive layer 21 and the second adhesive layer 22.

The double-sided pressure-sensitive adhesive sheet 2 according to the present embodiment is sandwiched between the two release sheets 31 and 32 so as to be in contact with the release surfaces of the two release sheets 31 and 32. Sheet 1 However, the release sheet 31 and/or the release sheet 32 may not necessarily be laminated on the double-sided pressure-sensitive adhesive sheet 2. In addition, the release surface of the release sheet in the present specification refers to a surface having releasability in the release sheet, and includes both a surface subjected to a release treatment and a surface exhibiting releasability without performing the release treatment. ..

In the present embodiment, the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are the outermost layers of the double-sided pressure-sensitive adhesive sheet 2, respectively, and the first pressure-sensitive adhesive layer 21 contacts the release surface of the release sheet 31. Thus, the second adhesive layer 22 is in contact with the release surface of the release sheet 32, but is not limited to this. Further, in the present embodiment, the intermediate layer 23 and the first adhesive layer 21 are directly laminated, and the intermediate layer 23 and the second adhesive layer 22 are directly laminated, but the present invention is not limited to this. Not something.

The glass transition temperature (Tg) of the intermediate layer 23 in the present embodiment is 0° C. or higher and 60° C. or lower. Since the glass transition temperature of the intermediate layer 23 is within such a range, the intermediate layer 23 becomes somewhat hard at room temperature. Thereby, the film strength of the double-sided pressure-sensitive adhesive sheet 2 as a whole is improved and the workability is improved. For example, when the double-sided pressure-sensitive adhesive sheet 1 with a release sheet is cut, the double-sided pressure-sensitive adhesive sheet 2 itself is less likely to be crushed, and due to the presence of the intermediate layer 23, the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 2 which are relatively easily crushed. Since the cross-sectional area of the pressure-sensitive adhesive layer 22 also becomes small, it is possible to suppress the occurrence of problems such as the pressure-sensitive adhesive sticking out at the cut surface and the pressure-sensitive adhesive sticking to the blade.

On the other hand, when the glass transition temperature of the intermediate layer 23 is within the above range, the intermediate layer 23 is softened by heating, and the double-sided pressure-sensitive adhesive sheet 2 as a whole becomes excellent in flexibility. Therefore, when the double-sided pressure-sensitive adhesive sheet 2 is attached to an adherend having a step (for example, a display member constituting member), by heating the double-sided pressure-sensitive adhesive sheet 2, the double-sided pressure-sensitive adhesive sheet 2 has a step followability (initial step difference). Followability) is excellent, and it is possible to suppress the formation of gaps, floats, etc. near the step.

From the above viewpoint, the glass transition temperature of the intermediate layer 23 is preferably 20° C. or higher, and particularly preferably 30° C. or higher. Further, the glass transition temperature is preferably 60° C. or lower, and particularly preferably 40° C. or lower. In addition, the measuring method of the glass transition temperature in this specification is as showing in the test example mentioned later.

Here, as described below, when the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are active energy ray-curable, preferably when the intermediate layer 23 is also active energy ray-curable. By curing these layers by irradiation with active energy rays, the double-sided pressure-sensitive adhesive sheet 2 has not only excellent initial step followability but also excellent step followability under high temperature and high humidity conditions. For example, even when a laminated body including an adherend having a step (for example, a display member constituting member) and the double-sided pressure-sensitive adhesive sheet 2 is placed under conditions of 85° C. and 85% RH for 72 hours, bubbles and floating near the step. The occurrence of peeling and the like is suppressed. The term "cured (cured state)" as used herein means a state in which a new higher-order structure is formed by irradiation with active energy rays, and further formation of higher-order structures is almost eliminated by further irradiation with active energy rays. Whether or not the higher-order structure is further formed can be determined by, for example, the amount of change in the gel fraction. Specifically, when the increase in the gel fraction due to the further irradiation with active energy rays is minute (preferably 5% or less), it can be said to be in a cured state.

1. First pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer The first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are not particularly limited as long as the above-mentioned effects of the intermediate layer 23 are exhibited, It may be active energy ray curable or active energy ray non-curable, but at least one is preferably active energy ray curable, and the first adhesive layer 21 and the second adhesive layer 21 It is more preferable that all of the pressure-sensitive adhesive layers 22 are curable with active energy rays. As a result, the double-sided pressure-sensitive adhesive sheet 2 is excellent not only in the initial step followability but also in the step followability under high temperature and high humidity conditions. The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer may be the same pressure-sensitive adhesive or different pressure-sensitive adhesives.

When at least one of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is non-curable with active energy rays, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is, for example, an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive. It may be any of adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives and the like. The pressure-sensitive adhesive may be emulsion type, solvent type or solventless type, and may be crosslinked type or non-crosslinked type. Among the above, the acrylic adhesive is preferable.

The active-energy-ray-non-curable pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive that has been cured with active energy rays (adhesive that was active energy ray-curable before curing).

When at least one of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is active energy ray-curable, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is an active energy ray-curable pressure-sensitive adhesive (active energy ray-curable adhesive). It is a curable adhesive). The active energy ray-curable pressure-sensitive adhesive preferably contains at least one of an active energy ray-curable monomer, an oligomer and a polymer, or a mixture thereof, in addition to that, an active energy ray-non-curable monomer, It may contain either oligomers and polymers, or mixtures thereof.

The active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester polymer (A) and an active energy ray-curable compound (B) (hereinafter referred to as "pressure-sensitive adhesive composition P"). In some cases). The adhesive composition P preferably further contains a crosslinking agent (C). In this case, the obtained pressure-sensitive adhesive comprises a pressure-sensitive adhesive obtained by crosslinking the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P with the crosslinking agent (C) (active energy ray-curable compound ( B) is preferably present in the pressure-sensitive adhesive layer without being polymerized). In addition, in this specification, a (meth)acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. The same applies to other similar terms. In addition, the concept of “copolymer” is also included in “polymer”.

(1) Active energy ray-curable pressure-sensitive adhesive (1-1) (meth)acrylic acid ester polymer (A)
The (meth)acrylic acid ester polymer (A) contains a (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, and thus has favorable adhesiveness. Can be expressed. Examples of the (meth)acrylic acid alkyl ester whose alkyl group has 1 to 20 carbon atoms include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylic acid n-. Butyl, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylic acid Examples thereof include n-dodecyl, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among them, from the viewpoint of further improving the tackiness, a (meth)acrylic acid ester having an alkyl group having 1 to 8 carbon atoms is preferable, and n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is particularly preferable. .. In addition, these may be used individually and may be used in combination of 2 or more type.

The (meth)acrylic acid ester polymer (A) preferably contains 40% by mass or more of a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer. It is particularly preferable to contain 50% by mass or more, and further preferably 60% by mass or more. When the content of the (meth)acrylic acid alkyl ester is 40% by mass or more, suitable tackiness can be imparted to the (meth)acrylic acid ester polymer (A). Further, it is preferable that the content of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is 90% by mass or less, particularly 80% by mass or less, and further 70% by mass or less. Is preferred. By setting the content of the (meth)acrylic acid alkyl ester to 90% by mass or less, a desired amount of another monomer component can be introduced into the (meth)acrylic acid ester polymer (A).

The (meth)acrylic acid ester polymer (A) preferably contains a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer) as a monomer unit constituting the polymer. The reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (C) described below, whereby a crosslinked structure (three-dimensional network structure) is formed, and a pressure-sensitive adhesive having a desired cohesive force is obtained. To be

Examples of the reactive functional group-containing monomer contained in the (meth)acrylic acid ester polymer (A) as a monomer unit constituting the polymer include a monomer having a hydroxyl group in the molecule (a hydroxyl group-containing monomer) and a carboxyl group in the molecule. Preferable examples include a monomer having a group (carboxyl group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer which is excellent in reactivity with the crosslinking agent (C) and has little adverse effect on the adherend is particularly preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and (meth ) Hydroxyalkyl esters of (meth)acrylic acid such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate. Among them, 2-hydroxyethyl (meth)acrylate from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth)acrylic acid ester polymer (A) with the crosslinking agent (C) and the copolymerizability with other monomers. Alternatively, 4-hydroxybutyl (meth)acrylate is preferable. These may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of the reactivity of the carboxyl group in the obtained (meth)acrylic acid ester polymer (A) with the crosslinking agent (C) and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used alone or in combination of two or more. In addition, the nitrogen atom-containing monomer described later is excluded from the amino group-containing monomer.

When the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the content is preferably 3% by mass or more as a lower limit, and particularly 10% by mass. % Or more, and more preferably 15% by mass or more. The upper limit of the content is preferably 35% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. When the (meth)acrylic acid ester polymer (A) contains the hydroxyl group-containing monomer in the above amount as a monomer unit, a predetermined amount of hydroxyl group will remain in the obtained pressure-sensitive adhesive. Hydroxyl groups are hydrophilic groups, and if a certain amount of such hydrophilic groups is present in the pressure-sensitive adhesive, it will penetrate into the pressure-sensitive adhesive even if the pressure-sensitive adhesive is placed under high temperature and high humidity conditions. The compatibility with the water content is good, and as a result, the whitening of the pressure-sensitive adhesive when it is returned to room temperature and normal humidity is suppressed (excellent wet heat and whitening resistance).

When the (meth)acrylic acid ester polymer (A) contains a carboxy group-containing monomer as a monomer unit constituting the polymer, its content is preferably 0.5% by mass or more as a lower limit, It is more preferably 3% by mass or more, and particularly preferably 7% by mass or more. The upper limit of the content is preferably 20% by mass or less, more preferably 17% by mass or less, and particularly preferably 13% by mass or less.

In the case where the adherend is easily affected by an acid, such as a transparent conductive film or a metal wiring, the (meth)acrylic acid ester polymer (A) is used as a monomer unit constituting the polymer. In addition, it is preferable not to contain a carboxyl group-containing monomer. Thereby, for example, it is possible to prevent the transparent conductive film and the metal wiring from being corroded and changing the resistance value of the transparent conductive film.

Here, "does not contain a monomer having a carboxyl group" means that it does not substantially contain a monomer having a carboxyl group, and does not contain a carboxyl group-containing monomer at all, or a transparent conductive film or metal having a carboxyl group. The inclusion of a carboxyl group-containing monomer to the extent that corrosion of wiring or the like does not occur. Specifically, the (meth)acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit in an amount of 0.1% by mass or less, preferably 0.01% by mass or less. It is acceptable.

It is also preferable that the (meth)acrylic acid ester polymer (A) contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the copolymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the alicyclic structure-containing monomer is present in the polymer to widen the interval between the polymers, and the resulting pressure-sensitive adhesive can have excellent flexibility. .. Therefore, when the (meth)acrylic acid ester polymer (A) has the alicyclic structure-containing monomer as a constituent monomer unit, the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P is It will be excellent.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may partially have an unsaturated bond. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. From the viewpoint of widening the distance between the obtained (meth)acrylic acid ester polymers (A) and effectively exhibiting the flexibility of the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure ( It is preferably a polycyclic structure). Further, in consideration of the compatibility of the (meth)acrylic acid ester polymer (A) with other components, the polycyclic structure is particularly preferably a bicyclic ring to a tetracyclic ring. Further, from the viewpoint of effectively exhibiting the action of the flexibility of the pressure-sensitive adhesive as in the above, the carbon number of the alicyclic structure (refers to all the carbon numbers of the portion forming the ring, a plurality of rings are independent When present, the total number of carbon atoms) is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, although the upper limit of the number of carbon atoms of the alicyclic structure is not particularly limited, it is preferably 15 or less, and particularly preferably 10 or less from the viewpoint of compatibility as in the above.

Examples of the alicyclic structure include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.) , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, cubane skeleton, basketane skeleton, hausan skeleton, spiro skeleton, and the like, among which, more excellent durability is exhibited, Those containing a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), adamantane skeleton (carbon number of alicyclic structure: 10) or isobornyl skeleton (carbon number of alicyclic structure: 7) are preferable, Those containing an isobornyl skeleton are preferred.

The alicyclic structure-containing monomer is preferably a (meth)acrylic acid ester monomer containing the above skeleton, and specifically, (meth)acrylic acid cyclohexyl, (meth)acrylic acid dicyclopentanyl, (meth) Examples thereof include adamantyl acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among them, (meth)acrylic exhibiting superior durability. Dicyclopentanyl acid, adamantyl (meth)acrylate or isobornyl (meth)acrylate is preferable, and isobornyl (meth)acrylate is particularly preferable. These may be used alone or in combination of two or more.

When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the (meth)acrylic acid ester polymer (A) has an alicyclic structure. The content of the contained monomer is preferably 5% by mass or more, particularly preferably 8% by mass or more, and further preferably 10% by mass or more. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 40% by mass or less, and particularly 30% by mass or less, of an alicyclic structure-containing monomer as a monomer unit constituting the polymer. Is preferable, and it is more preferable that the content is 20% by mass or less. When the content of the alicyclic structure-containing monomer is in the above range, the initial step followability of the obtained pressure-sensitive adhesive becomes more excellent.

The (meth)acrylic acid ester polymer (A) also preferably contains a monomer having a nitrogen atom in the molecule (nitrogen atom-containing monomer) as a monomer unit constituting the copolymer. The presence of a nitrogen atom-containing monomer in the polymer as a constitutional unit promotes the reaction between the acrylic ester copolymer (A) and the cross-linking agent (C) or imparts polarity to the pressure-sensitive adhesive, The cohesive force of itself can be increased.

Examples of the nitrogen atom-containing monomer include a monomer having a tertiary amino group, a monomer having an amide group, and a monomer having a nitrogen-containing heterocycle. Among them, a monomer having a nitrogen-containing heterocycle is preferable.

Examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloyl. Pyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N-(meth)acryloylmorpholine, which exhibits more excellent adhesive strength, is preferable, and N-acryloylmorpholine is particularly preferable.

In addition, as the nitrogen atom-containing monomer other than the above-mentioned monomer having a nitrogen-containing heterocycle, for example, (meth)acrylamide, N-methyl(meth)acrylamide, N-methylol(meth)acrylamide, N-tert-butyl(meth ) Acrylamide, N,N-dimethyl(meth)acrylamide, N,N-ethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-phenyl(meth)acrylamide , Dimethylaminopropyl(meth)acrylamide, N-vinylcaprolactam, dimethylaminoethyl(meth)acrylate, etc. can also be used.
The above nitrogen atom-containing monomers may be used alone or in combination of two or more.

When the (meth)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the (meth)acrylic acid ester polymer (A) has a nitrogen atom-containing monomer of 1 The content is preferably at least mass%, more preferably at least 2 mass%, further preferably at least 5 mass%. The (meth)acrylic acid ester polymer (A) preferably contains a nitrogen atom-containing monomer in an amount of 40% by mass or less, and particularly preferably 25% by mass or less, as a monomer unit constituting the polymer. Further, it is preferable that the content is 15% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the cohesive force of the obtained pressure-sensitive adhesive is effectively improved.

If desired, the (meth)acrylic acid ester polymer (A) may contain another monomer as a monomer unit constituting the polymer. As the other monomer, a monomer not containing a reactive functional group is preferable. Examples of such other monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 100,000 or more, particularly preferably 200,000 or more, and further preferably 300,000 or more. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is at least the above, the resulting adhesive will have a relatively higher coating strength and will follow a step difference under high temperature and high humidity conditions. The property is improved. The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 900,000 or less as an upper limit value, particularly preferably 800,000 or less, and further preferably 700,000 or less. preferable. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is not more than the above, the initial step followability of the obtained pressure-sensitive adhesive becomes more excellent. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

In the pressure-sensitive adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more.

(1-2) Active energy ray curable compound (B)
When the pressure-sensitive adhesive composition P contains the active energy ray-curable compound (B), the obtained pressure-sensitive adhesive layer becomes active energy ray-curable. The active energy ray curability in the pressure-sensitive adhesive layer has adhesiveness before irradiation with active energy rays, and is cured by irradiation with active energy rays after sticking to an adherend to improve adhesive strength. It is a property.

Here, when the said adhesive composition P contains the below-mentioned crosslinking agent (C) in addition to the active energy ray-curable compound (B), in the adhesive layer obtained, the above-mentioned (meth)acryl A crosslinked structure is formed by the acid ester polymer (A) and the crosslinking agent (C), and the active energy ray-curable compound (B) is present in the pressure-sensitive adhesive layer in an unreacted state (without being polymerized). Presumed. When the adhesive layer is irradiated with active energy rays, the active energy ray-curable compounds (B) are polymerized with each other, and the polymerized active energy ray-curable compounds (B) are (meth)acrylic acid. It is presumed that the ester polymer (A) is entangled in the crosslinked structure (three-dimensional network structure) of the ester polymer (A), so that the pressure-sensitive adhesive layer is cured. Since the pressure-sensitive adhesive having such a higher-order structure has a high cohesive force and exhibits a relatively high elastic modulus, double-sided pressure-sensitive adhesive having the cured first pressure-sensitive adhesive layer 21 and/or the second pressure-sensitive adhesive layer 22 as the outermost layer. The sheet 2 (corresponding to the double-sided pressure-sensitive adhesive sheet 2'after curing described below) has excellent step followability under high temperature and high humidity conditions.

The active energy ray-curable compound (B) is not particularly limited as long as it is a compound that is cured by irradiation with an active energy ray and can obtain the above effects, and may be any of a monomer, an oligomer and a polymer. It may be a mixture of. Among these, a polyfunctional acrylate-based monomer having a molecular weight of less than 1000, which has excellent compatibility with the (meth)acrylic acid ester polymer (A) and the like, can be preferably mentioned.

Examples of the polyfunctional acrylate-based monomer having a molecular weight of less than 1000 include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di. (Meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone modified dicyclopentenyl di(meth)acrylate, ethylene oxide modified Di(meth)acrylate phosphate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl] Bifunctional type such as fluorene; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylol Trifunctional type such as propane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl)isocyanurate; diglycerin tetra(meth)acrylate, pentaerythritol Tetra(meth)acrylate and other tetrafunctional types; propionic acid modified dipentaerythritol penta(meth)acrylate and other five functional types; dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate and other 6 Functional type etc. are mentioned. Among the above, pentaerythritol tri(meth)acrylate and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate are preferable from the viewpoint of the step followability of the obtained pressure-sensitive adhesive. These may be used alone or in combination of two or more.

As the active energy ray-curable compound (B), an active energy ray-curable acrylate-based oligomer can also be used. The acrylate-based oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

The upper limit of the weight average molecular weight of the acrylate-based oligomer is preferably 50,000 or less, and particularly preferably 40,000 or less. The lower limit of the weight average molecular weight is preferably 1,000 or more, and particularly preferably 3,000 or more. These acrylate-based oligomers may be used alone or in combination of two or more.

Further, as the active energy ray-curable compound (B), an adduct acrylate-based polymer in which a group having a (meth)acryloyl group is introduced into a side chain can also be used. Such an adduct acrylate-based polymer uses a copolymer of (meth)acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and uses it as a part of the crosslinkable functional group of the copolymer. , A (meth)acryloyl group and a compound having a group capable of reacting with a crosslinkable functional group.

The lower limit of the weight average molecular weight of the adduct acrylate-based polymer is preferably 50,000 or more, and particularly preferably 100,000 or more. In addition, the weight average molecular weight is preferably 900,000 or less as an upper limit, and particularly preferably 500,000 or less.

As the active energy ray-curable compound (B), one kind may be selected from the above-mentioned polyfunctional acrylate-based monomers, acrylate-based oligomers and adduct acrylate-based polymers, or two or more kinds may be used in combination. It is also possible to use it in combination with other active energy ray-curable components.

The content of the active energy ray-curable compound (B) in the pressure-sensitive adhesive composition P is from the viewpoint of improving the cohesive force of the obtained pressure-sensitive adhesive and making the step followability under high temperature and high humidity conditions excellent. With respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A), the lower limit value is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. Particularly preferred. On the other hand, from the viewpoint of preventing the active energy ray-curable compound (B) from being phase-separated from the (meth)acrylic acid ester polymer (A), the content is 50 parts by mass or less as an upper limit. The amount is preferably 20 parts by mass or less, and more preferably 12 parts by mass or less in view of improving the step followability under high temperature and high humidity conditions.

(1-3) Crosslinking agent (C)
The adhesive composition P preferably contains a crosslinking agent (C). The adhesive composition P contains the crosslinking agent (C) to crosslink the (meth)acrylic acid ester polymer (A) to form a three-dimensional network structure and improve the cohesive force of the obtained adhesive. Thus, the step followability under high temperature and high humidity conditions can be further improved.

The cross-linking agent (C) may be any as long as it reacts with the reactive group of the (meth)acrylic acid ester polymer (A), and examples thereof include an isocyanate cross-linking agent, an epoxy cross-linking agent, an amine cross-linking agent, Melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. Can be mentioned. When the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, it is preferable to use an isocyanate crosslinking agent having excellent reactivity with the hydroxyl group. Further, when the (meth)acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, an epoxy cross-linking agent excellent in reactivity with the carboxyl group is used. It is preferable. The crosslinking agent (C) may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, aromatic polyisocyanates such as xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. And their biurets, isocyanurates, and adducts which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate, is preferable from the viewpoint of reactivity with hydroxyl groups.

Examples of the epoxy cross-linking agent include 1,3-bis(N,N′-diglycidylaminomethyl)cyclohexane, N,N,N′,N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples thereof include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine. Among them, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane is preferable from the viewpoint of reactivity with the carboxyl group.

The content of the cross-linking agent (C) in the adhesive composition P is preferably 0.001 part by mass or more as a lower limit value with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A), In particular, it is preferably 0.01 part by mass or more, and further preferably 0.02 part by mass or more. The upper limit is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and further preferably 1 part by mass or less.

When the content of the cross-linking agent (C) is within the above range, the cohesive force of the obtained pressure-sensitive adhesive becomes favorable, and the step followability of the obtained pressure-sensitive adhesive under high temperature and high humidity conditions is improved.

(1-4) Photopolymerization initiator (D)
When ultraviolet rays are used as active energy rays for irradiation when the active energy ray-curable adhesive is cured, the adhesive composition P preferably further contains a photopolymerization initiator (D). By thus containing the photopolymerization initiator (D), the active energy ray-curable compound (B) can be efficiently polymerized, and the curing time by polymerization and the active energy ray irradiation dose can be reduced. be able to.

Examples of such a photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy. 2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-[4- (Methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4 , 6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator (D) in the adhesive composition P is preferably 0.1 part by mass or more as a lower limit with respect to 100 parts by mass of the active energy ray-curable compound (B), It is particularly preferably 1 part by mass or more. Further, the upper limit is preferably 30 parts by mass or less, and particularly preferably 10 parts by mass or less.

(1-5) Various additives In the adhesive composition P, if desired, various additives commonly used in acrylic pressure-sensitive adhesives, for example, silane coupling agents, antistatic agents, tackifiers, and antioxidants. A light stabilizer, a softening agent, a filler, a refractive index adjusting agent and the like can be added.

The pressure-sensitive adhesive composition P represents a mixture of various components remaining in the pressure-sensitive adhesive as it is or in a reacted state, and is a component removed in a drying step or the like, for example, a polymerization solvent described later. The diluent solvent is not included in the adhesive composition P.

(1-6) Production of Adhesive Composition Adhesive composition P was produced by producing (meth)acrylic acid ester polymer (A), and obtained (meth)acrylic acid ester polymer (A) It can be produced by mixing the energy ray-curable compound (B) and, if desired, adding a crosslinking agent (C), a photopolymerization initiator (D) and an additive.

The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, optionally using a polymerization initiator. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more kinds may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane1-carbonitrile), and ,2'-Azobis(2,4-dimethylvaleronitrile),2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate) 4,4'-azobis(4-cyanovaleric acid),2,2'-azobis(2-hydroxymethylpropionitrile),2,2'-azobis[2-(2-imidazolin-2-yl) Propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxy. Dicarbonate, t-butyl peroxy neodecanoate, t-butyl peroxy vivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like can be mentioned.

In the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

When the (meth)acrylic acid ester polymer (A) is obtained, the solution of the (meth)acrylic acid ester polymer (A) is added to the active energy ray-curable compound (B), optionally a cross-linking agent (C), and light. The adhesive composition P (coating solution) diluted with the solvent can be obtained by adding the polymerization initiator (D), the additive and the diluting solvent and mixing them sufficiently. In any of the above components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component alone is previously diluted with a diluting solvent. It may be dissolved or diluted and then mixed with other components.

Examples of the diluent solvent include hexane, heptane, aliphatic hydrocarbons such as cyclohexane, toluene, aromatic hydrocarbons such as xylene, methylene chloride, halogenated hydrocarbons such as ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, acetone, methyl ethyl ketone, ketones such as 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration/viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, the pressure-sensitive adhesive composition P is diluted so as to have a concentration of 10 to 60% by mass. In addition, when obtaining the coating solution, addition of a diluting solvent or the like is not a necessary condition, and the diluting solvent may not be added as long as the viscosity of the adhesive composition P allows the coating. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth)acrylic acid ester polymer (A) as a diluting solvent.

(1-7) Production of pressure-sensitive adhesive The active energy ray-curable pressure-sensitive adhesive can be preferably obtained by crosslinking the pressure-sensitive adhesive composition P. Crosslinking of the adhesive composition P can usually be performed by heat treatment. The heat treatment can also be used as a drying treatment when the diluent solvent or the like is volatilized from the coating film of the adhesive composition P applied to a desired object.

The heating temperature of the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23° C. and 50% RH), if necessary. When this curing period is required, after the curing period has elapsed, when the curing period is unnecessary, after the heat treatment is completed, the adhesive is formed.

By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is sufficiently crosslinked (via the crosslinking agent (C) when the crosslinking agent (C) is contained). ..

(2) Thickness of pressure-sensitive adhesive layer The thickness of the first pressure-sensitive adhesive layer 21 and the thickness of the second pressure-sensitive adhesive layer 22 are each preferably 15 μm or more, and particularly preferably 30 μm or more, Further, it is preferably 50 μm or more. Further, the thickness is preferably 300 μm or less, particularly preferably 150 μm or less, and further preferably 100 μm or less. When the thickness is within the above range, the effects of the step followability and workability described above can be more effectively exhibited. The thickness of the first adhesive layer 21 and the thickness of the second adhesive layer 22 may be the same or different. For example, from the viewpoint of step followability, it may be preferable that the pressure-sensitive adhesive layer on the side to be adhered to the adherend having a step is thicker than the other pressure-sensitive adhesive layer.

2. Intermediate Layer The intermediate layer 23 has a glass transition temperature of 0° C. or higher and 60° C. or lower as described above. From the viewpoint of obtaining excellent processability, the glass transition temperature is preferably 20°C or higher, more preferably 27°C or higher. On the other hand, the glass transition temperature is preferably 50° C. or lower, more preferably 40° C. or lower, and particularly preferably 30° C. or lower, from the viewpoint of excellent initial step followability. ..

The intermediate layer 23 may be non-curable with active energy rays or curable with active energy rays. However, when at least one of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is active energy ray-curable, the intermediate layer 23 is also preferably active energy ray-curable. This is because the active energy ray-curable pressure-sensitive adhesive layer and the active energy ray-curable intermediate layer react with each other at their interfaces to form a chemical bond. As a result, the adhesive strength between the pressure-sensitive adhesive layer and the intermediate layer 23 is increased, delamination is suppressed, and the double-sided pressure-sensitive adhesive sheet 2 is more excellent in step followability under high temperature and high humidity conditions.

The active energy ray curability of the intermediate layer 23 exhibits a relatively small elasticity before irradiation with the active energy ray, and the adhesive layer is cured by irradiation with the active energy ray after being attached to the adherend to improve elasticity. It is a property.

In order to obtain the intermediate layer 23 having the above glass transition temperature, the material forming the intermediate layer 23 may be a resin having a glass transition temperature of 0° C. or higher and 60° C. or lower (hereinafter referred to as “resin (E)”). .) is preferably contained. That is, the intermediate layer 23 is preferably composed of a resin composition containing the resin (E) (hereinafter sometimes referred to as “resin composition Q”).

(1) Resin composition (1-1) Resin (E)
The glass transition temperature of the resin (E) contained in the material (resin composition Q) constituting the intermediate layer 23 is 0° C. or higher and 60° C. or lower, so that the glass transition temperature of the intermediate layer 23 itself is in the range described above. It is easy to enter. From this viewpoint, the glass transition temperature of the resin (E) is particularly preferably 20° C. or higher, and more preferably 30° C. or higher. The glass transition temperature of the resin (E) is particularly preferably 50°C or lower, and more preferably 40°C or lower.

Examples of the resin (E) include a vinyl acetate resin and a polyolefin resin. Among them, a vinyl acetate resin that can make the double-sided pressure-sensitive adhesive sheet 2 particularly excellent in initial step followability is preferable. As the vinyl acetate resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, for example, ethylene-vinyl acetate copolymer, etc. Is mentioned.

The lower limit of the weight average molecular weight of the vinyl acetate resin is preferably 10,000 or more, particularly preferably 20,000 or more, and further preferably 100,000 or more. When the lower limit of the weight average molecular weight of the vinyl acetate resin is at least the above, the film forming property and processability of the intermediate layer 23 are improved. The upper limit of the weight average molecular weight of the vinyl acetate resin is preferably 1,000,000 or less, more preferably 700,000 or less, and further preferably 500,000 or less. When the upper limit of the weight average molecular weight of the vinyl acetate resin is not more than the above, the step followability is further improved.

The resin composition Q preferably contains the above resin (E) as a main component, specifically, preferably contains 50% by mass or more of the resin (E), and particularly preferably contains 60% by mass or more. It is preferable that the content is 80% by mass or more. The resin composition Q may consist only of the resin (E). On the other hand, when the resin composition Q contains other components (for example, the active energy ray-curable compound (F) and the photopolymerization initiator (G) described later), the resin (E) is contained in an amount of 95% by mass or less. It is preferably contained, particularly preferably 93 mass% or less, and further preferably 90 mass% or less.

(1-2) Other components When the intermediate layer 23 is active energy ray-curable, the resin composition Q may contain an active energy ray-curable compound (F) in addition to the resin (E). preferable. As the active energy ray-curable compound (F), the same active energy ray-curable compound as the active energy ray-curable compound (B) that can be used in the above-mentioned active energy ray-curable pressure-sensitive adhesive can be used. From the viewpoint of interlayer adhesion, it is particularly preferable to use an active energy ray-curable compound of the same kind as the active energy ray-curable compound (B) contained in the active energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, Furthermore, it is preferable to use the same active energy ray-curable compound as the active energy ray-curable compound (B) contained in the active energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer.

The content of the active energy ray-curable compound (F) in the resin composition Q is 100 parts by mass of the resin (E) from the viewpoint of excellent interlayer adhesion and step followability under high temperature and high humidity conditions. On the other hand, the lower limit is preferably 1 part by mass or more, particularly preferably 5 parts by mass or more, and is 10 parts by mass or more from the viewpoint of further improving the initial step followability. More preferable. On the other hand, the content is preferably 40 parts by mass or less as an upper limit, particularly preferably 30 parts by mass or less, and particularly 20 parts by mass or less from the viewpoint of not lowering the glass transition temperature of the intermediate layer 23 too much. Is more preferable.

When ultraviolet rays are used as the active energy rays to be irradiated when the active energy ray-curable resin composition Q is cured, the resin composition Q may further contain a photopolymerization initiator (G). preferable. As the photopolymerization initiator (G), the same photopolymerization initiator as the photopolymerization initiator (D) that can be used in the above-mentioned active energy ray-curable pressure-sensitive adhesive can be used.

The content of the photopolymerization initiator (G) in the resin composition Q is preferably 0.1 part by mass or more as a lower limit, and particularly 1 It is preferable that the amount is at least parts by mass. Further, the upper limit is preferably 30 parts by mass or less, and particularly preferably 10 parts by mass or less.

On the other hand, when the resin composition Q is non-curable with active energy rays, the resin composition Q constitutes the first adhesive layer 21 and the second adhesive layer 22 in addition to the resin (E). It is preferable that the pressure-sensitive adhesive contains a crosslinkable monomer capable of forming a crosslinked structure with the reactive functional group (derived from the reactive functional group-containing monomer) contained in the (meth)acrylic acid ester polymer (A). It is particularly preferable to contain a crosslinking agent for forming the crosslinked structure. As the crosslinkable monomer, those having the same functional group as the reactive functional group contained in the (meth)acrylic acid ester polymer (A) are preferable, and for example, the (meth)acrylic acid ester polymer (A) is constituted. It is preferable to use the same monomer as the reactive functional group-containing monomer. Further, as the cross-linking agent, it is preferable to use the same one as the cross-linking agent (C) in the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22. The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 may be an active energy ray curable pressure-sensitive adhesive or an active energy ray non-curable pressure-sensitive adhesive. Good.

When the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 and the resin composition Q are thermally crosslinked in the above case, the (meth)acrylic acid ester polymer (A) is obtained. And the crosslinkable monomer crosslink through the crosslinker (C) in the pressure-sensitive adhesive composition or the crosslinker in the resin composition Q to chemically bond. Thereby, the adhesiveness between the first adhesive layer 21 and the intermediate layer 23, the second adhesive layer 22 and the intermediate layer 23 is increased, and the intermediate layer 23 and the first adhesive layer 21 and the second adhesive agent are increased. Delamination at the interface with the layer 22 is suppressed.

If desired, various additives such as an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softening agent, a filler, and a refractive index adjusting agent can be added to the resin composition Q.

The resin composition Q represents a mixture of various components remaining in the intermediate layer as it is or in a reacted state, and the components removed in the drying step or the like, for example, the below-mentioned diluted solvent is , Not included in the resin composition Q.

(1-3) Production of Resin Composition/Intermediate Layer The resin composition Q contains the resin (E) and, if desired, an active energy ray-curable compound (F), a photopolymerization initiator (D), an additive and the like. It can be manufactured by adding. When this resin composition Q is applied, a diluent solvent is optionally added to obtain a resin composition Q (coating solution) diluted with the solvent.

The intermediate layer 23 can be formed, for example, by applying a coating solution of the resin composition Q and drying. This drying can usually be performed by heat treatment. The conditions for the heat treatment are the same as the conditions for the heat treatment at the time of producing the pressure-sensitive adhesive described above.

In the case where the intermediate layer 23 is non-curable with active energy rays and the resin composition Q contains the active energy ray-curable compound (F), after the above-mentioned coating and drying, the active energy is further increased. The resin composition Q may be cured by irradiation with rays, and this may be used as the intermediate layer 23. However, in consideration of the initial step followability, after the display body constituent member having a step and another display body constituent member are bonded together by the double-sided pressure-sensitive adhesive sheet 2, the intermediate layer 23 ( It is preferable to cure the constituent resin composition Q).

(2) Thickness of Intermediate Layer The ratio of the thickness of the intermediate layer 23 to the total thickness of the first adhesive layer 21 and the second adhesive layer 22 is preferably 0.01 or more, and particularly 0. It is preferably 0.05 or more, and more preferably 0.15 or more. Further, the ratio is preferably 2 or less, particularly preferably 1.5 or less, further preferably 1 or less, and most preferably 0.5 or less. When the ratio is 0.01 or more, the effects of the step follow-up and the workability described above can be more effectively exhibited. The thickness of each layer is a value measured according to JIS K7130.

The thickness of the intermediate layer 23 is preferably 5 μm or more, particularly preferably 10 μm or more, and further preferably 15 μm or more. Further, the thickness is preferably 100 μm or less, particularly preferably 70 μm or less, and further preferably 50 μm or less. When the thickness is within the above range, the effects of the step followability and workability described above can be more effectively exhibited.

3. Release Sheets The release sheets 31 and 32 protect the adhesive surfaces that are in contact with the double-sided pressure-sensitive adhesive sheet 2 until they are used, and are peeled off when the double-sided pressure-sensitive adhesive sheet 2 is used. In the double-sided pressure-sensitive adhesive sheet 1 with release sheet according to this embodiment, one of the release sheets 31 and 32 is not always necessary.

Examples of the release sheets 31 and 32 include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. Further, these crosslinked films are also used. Furthermore, these laminated films may be used.

It is preferable that the release surface of the release sheets 31 and 32 (particularly the surface in contact with the double-sided pressure-sensitive adhesive sheet 2) is subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. It is preferable that one of the release sheets 31 and 32 is a heavy release type release sheet having a large release force, and the other release sheet is a light release type release sheet having a low release force.

The thickness of the release sheets 31 and 32 is not particularly limited, but is usually about 20 to 150 μm.

4. Physical Properties etc. of Adhesive Sheet The total thickness of the double-sided adhesive sheet 2 is preferably 50 μm or more, particularly preferably 100 μm or more, and further preferably 150 μm or more. In addition, the total thickness is preferably 600 μm or less, particularly preferably 400 μm or less, and further preferably 300 μm or less. When the total thickness of the double-sided pressure-sensitive adhesive sheet 2 is within the above range, the effects of the step followability and workability described above can be exhibited more favorably.

The lower limit of the Young's modulus of the double-sided pressure-sensitive adhesive sheet 2 is preferably 0.01 Mpa or more, particularly preferably 0.5 Mpa or more, and further preferably 5 MPa or more. When the Young's modulus is at least the above lower limit value, the coating strength of the double-sided pressure-sensitive adhesive sheet 2 becomes high, and the workability of the double-sided pressure-sensitive adhesive sheet 1 with a release sheet becomes better. The upper limit of the Young's modulus is preferably 100 Mpa or less, more preferably 50 Mpa or less, and further preferably 20 Mpa or less. When the Young's modulus is less than or equal to the upper limit value, the double-sided pressure-sensitive adhesive sheet 2 has good flexibility, and the double-sided pressure-sensitive adhesive sheet 2 has more excellent initial step followability. The method of measuring the Young's modulus is as shown in the test example described later.

5. Production of double-sided pressure-sensitive adhesive sheet As an example of the production of the double-sided pressure-sensitive adhesive sheet 1 with a release sheet, the release liquid of one release sheet 31 is coated with the coating solution of the above-mentioned pressure-sensitive adhesive composition P and heat-treated to give a pressure-sensitive adhesive composition. The substance P is thermally cross-linked to form a coating layer, and the release sheet 31 with the coating layer of the adhesive composition P is obtained. Further, the coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 32, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer to form an adhesive composition. The release sheet 32 with the coating layer of the object P is obtained. Furthermore, the release liquid with the intermediate layer 23 is obtained by applying the coating liquid of the resin composition Q to the release surface of another release sheet and drying it.

Next, the release sheet 31 with the coating layer of the adhesive composition P and the release sheet with the intermediate layer 23 are attached to each other so that both layers are in contact with each other, and the release sheet is released from the intermediate layer 23. Next, the intermediate layer 23 and the release sheet 32 with the coating layer of the pressure-sensitive adhesive composition P are attached so that both layers are in contact with each other. When a curing period is required, the curing period is set, and when the curing period is not required, the coating layer of one of the laminated pressure-sensitive adhesive compositions P is the first pressure-sensitive adhesive layer 21 and the other pressure-sensitive adhesive layer is used as it is. The coating layer of the volatile composition P becomes the second pressure-sensitive adhesive layer 22. Thereby, the double-sided pressure-sensitive adhesive sheet 1 with the release sheet, in which the double-sided pressure-sensitive adhesive sheet 2 including the first pressure-sensitive adhesive layer 21, the intermediate layer 23, and the second pressure-sensitive adhesive layer 22 is sandwiched between the release sheets 31 and 32, is obtained. .. In addition, the curing of the coating layer of the adhesive composition may be performed after the coating layers of the adhesive composition are laminated to form three layers as described above, or may be performed before the lamination.

As a method of applying the coating solution of the adhesive composition P and the coating solution of the resin composition Q, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method or the like is used. can do.

Since the double-sided pressure-sensitive adhesive sheet 1 with the release sheet according to the present embodiment has good workability, when the double-sided pressure-sensitive adhesive sheet 1 with the release sheet is cut and the like, the pressure-sensitive adhesive sticks out on the cut surface and the pressure-sensitive adhesive is applied to the blade. It is possible to suppress the occurrence of problems such as adherence.

[Display]
As shown in FIG. 2, the display body 4 according to the present embodiment includes a first display body constituent member 51 (one display body constituent member) having a step on at least a surface on the side to be bonded, and a second display body constituent member 51. A display body constituent member 52 (another display body constituent member) and a double-sided pressure-sensitive adhesive sheet 2 which is located between them and which bonds the first display body constituent member 51 and the second display body constituent member 52 to each other. Prepared for. In the display body 4 according to the present embodiment, the first display body constituent member 51 has a step on the surface on the double-sided pressure-sensitive adhesive sheet 2 side, and specifically, has a step due to the printing layer 6. ..

When any of the first pressure-sensitive adhesive layer 21, the second pressure-sensitive adhesive layer 22 and the intermediate layer 23 in the double-sided pressure-sensitive adhesive sheet 2 is active energy ray-curable, the double-sided pressure-sensitive adhesive sheet 2 in the display body 4 has the above-described release. A double-sided pressure-sensitive adhesive sheet 2 with a sheet is obtained by curing the double-sided pressure-sensitive adhesive sheet 2 of the double-sided pressure-sensitive adhesive sheet 1 with a sheet by irradiation with active energy rays. Here, the active energy ray refers to an electromagnetic wave or a charged particle beam having an energy quantum, and specific examples thereof include ultraviolet rays and electron beams. Among the active energy rays, ultraviolet rays that are easy to handle are particularly preferable.

Irradiation of ultraviolet rays can be performed by a high pressure mercury lamp, a fusion H lamp, a xenon lamp or the like, and the irradiation amount of ultraviolet rays is preferably such that the illuminance is about 50 to 1000 mW/cm ² . Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2. On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation amount is preferably about 10 to 1000 krad.

Irradiation of the active energy ray to the double-sided pressure-sensitive adhesive sheet 2 is carried out after the first display body constituent member 51 and the second display body constituent member 52 are bonded to each other by the double-sided pressure-sensitive adhesive sheet 2 and then the first display body constituent member 51. It is preferable that the second display member constituting member 52 is passed through a member that transmits the active energy ray.

When the double-sided pressure-sensitive adhesive sheet 2 is irradiated with active energy rays, the active energy ray-curable compound (B) in the first pressure-sensitive adhesive layer 21 and the active energy ray-curable compound (B) in the second pressure-sensitive adhesive layer 22. , And at least one of the active energy ray-curable compound (F) in the intermediate layer 23 is polymerized and cured. The cured double-sided pressure-sensitive adhesive sheet 2'cured by irradiation with active energy rays has a very excellent step followability under high temperature and high humidity. Further, when at least one layer of the first adhesive layer 21 and the second adhesive layer 22 and the intermediate layer 23 are active energy ray curable, active energy ray curing is performed by irradiation with active energy rays. Since the active compound (B) and the active energy ray-curable compound (F) react with each other to chemically bond with each other, the adhesiveness between the active energy ray-curable pressure-sensitive adhesive layer and the intermediate layer 23 is increased, and the pressure-sensitive adhesive is increased. Delamination at the interface between the agent layer and the intermediate layer 23 is suppressed.

Examples of the display body 4 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Further, the display body 4 may be a member that constitutes a part of them.

The first display member constituting member 51 is preferably a protective panel made of a glass plate, a plastic plate or the like, or a laminated body including them. In this case, the printed layer 6 is generally formed in a frame shape on the double-sided adhesive sheet 2 side of the first display member constituting member 51.

The glass plate is not particularly limited, for example, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Examples include glass. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

Incidentally, various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one side or both sides of the glass plate or plastic plate, or an optical member. May be laminated. Moreover, the transparent conductive film and the metal layer may be patterned.

The second display body constituting member 52 is an optical member to be attached to the first display body constituting member 51, a display body module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic). EL) module), an optical member as a part of the display module, or a laminated body including the display module.

Examples of the optical member include a shatterproof film, a polarizing plate (polarizing film), a polarizer, a retardation film (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film. , A transflective film, a transparent conductive film, and the like. Examples of the anti-scattering film include a hard coat film in which a hard coat layer is formed on one surface of a base film.

The material forming the print layer 6 is not particularly limited, and a known material for printing is used. The thickness of the printing layer 6, that is, the lower limit of the height of the step is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, and most preferably 50 μm or more. preferable. When the lower limit value is equal to or more than the above, it is possible to sufficiently secure the concealing property such as making the electric wiring invisible to the viewer. The upper limit value is preferably 200 μm or less, more preferably 150 μm or less, particularly preferably 100 μm or less, and further preferably 80 μm or less. By setting the upper limit value to the above value or less, it is possible to prevent deterioration of the step followability of the double-sided PSA sheet 2 with respect to the printing layer 6.

In order to manufacture the display body 4, as an example, one release sheet 31 of the double-sided pressure-sensitive adhesive sheet with release sheet 1 is peeled off, and the exposed pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet 2 is removed by the first display body constituent member 51. The printed layer 6 is attached to the surface on the side where the printed layer 6 exists.

Then, the other release sheet 32 is peeled from the double-sided pressure-sensitive adhesive sheet 1 with the release sheet, and the exposed pressure-sensitive adhesive surface of the double-sided pressure-sensitive adhesive sheet 2 and the second display body component member 52 are bonded together. Further, as another example, the bonding order of the first display body constituting member 51 and the second display body constituting member 52 may be exchanged.

In performing the above-mentioned bonding, the double-sided pressure-sensitive adhesive sheet 1 with a release sheet is heated to soften the intermediate layer 23 in the double-sided pressure-sensitive adhesive sheet 2. The heating temperature may be any temperature as long as the intermediate layer 23 is softened, and is usually preferably 25° C. or higher and 70° C. or lower, particularly preferably 30° C. or higher and 60° C. or lower, and further 35 It is preferably not lower than 0°C and not higher than 50°C. By the above-mentioned heating, the double-sided pressure-sensitive adhesive sheet 2 as a whole has excellent flexibility and excellent initial step followability, so that the formation of a gap or floating near the step due to the printing layer 6 is suppressed.

Next, when any of the first pressure-sensitive adhesive layer 21, the second pressure-sensitive adhesive layer 22 and the intermediate layer 23 in the double-sided pressure-sensitive adhesive sheet 2 is active energy ray-curable, an active energy ray is applied to the double-sided pressure-sensitive adhesive sheet 2. Irradiation cures the active energy ray curable layer.

In the display body 4 described above, at least one layer of the first pressure-sensitive adhesive layer 21, the second pressure-sensitive adhesive layer 22, and the intermediate layer 23 in the double-sided pressure-sensitive adhesive sheet 2 is cured by irradiation with active energy rays. When it is, the double-sided pressure-sensitive adhesive sheet 2′ after curing is excellent in step followability even under high temperature and high humidity conditions. Therefore, even when the display body 4 is placed under high-temperature and high-humidity conditions (for example, 85° C., 85% RH, 72 hours), the occurrence of bubbles, floating, peeling, and the like near the step is suppressed. When at least one layer of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 and the intermediate layer 23 are those cured by irradiation with active energy rays, the pressure-sensitive adhesive layer and the intermediate layer are intermediate. Delamination at the interface with the layer 23 is also suppressed.

The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

For example, either one of the release sheets 31 and 32 in the double-sided pressure-sensitive adhesive sheet with release sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 31 and/or 32. Further, another layer may exist between the first pressure-sensitive adhesive layer 21 and/or the second pressure-sensitive adhesive layer 22 and the intermediate layer 23 in the double-sided pressure-sensitive adhesive sheet 2, or the double-sided pressure-sensitive adhesive sheet 2 Another layer may be present outside (on the side of the release sheets 31, 32) of the first pressure-sensitive adhesive layer 21 and/or the second pressure-sensitive adhesive layer 22 in.

Further, the first display member constituting member 51 may have a step other than the printing layer 6. Further, not only the first display body constituting member 51 but also the second display body constituting member 52 may have a step on the double-sided pressure-sensitive adhesive sheet 2 side.

Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
(1) Preparation of laminate having first pressure-sensitive adhesive layer or second pressure-sensitive adhesive layer (1-1) Preparation of (meth)acrylic acid ester polymer (A) 65 parts by mass of 2-ethylhexyl acrylate, N 5 parts by mass of acryloylmorpholine, 15 parts by mass of isobornyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylic acid ester polymer (A). When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described below, the weight average molecular weight (Mw) was 500,000.

(1-2) Preparation of Adhesive Composition P 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the above step (1-1) (solid content conversion value; the same applies hereinafter) and active energy 5 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300-1CL") as a radiation curable compound (B), and a crosslinking agent. 0.15 parts by mass of a tolylene diisocyanate cross-linking agent (manufactured by Toyochem Co., Ltd., product name "BHS-8515") as (C), and 1 part of benzophenone and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (D). 1 parts by mass (BASF Corporation, product name “Irgacure 500”) is mixed with 0.5 parts by mass, and the mixture is sufficiently stirred and diluted with methyl ethyl ketone to prepare the adhesive composition P. A coating solution was obtained.

(1-3) Production of Laminated Body A heavy release type release sheet in which the coating solution of the adhesive composition P obtained in the above step (1-2) is release-treated on one side of a polyethylene terephthalate film with a silicone release agent ( After coating with a knife coater on the release-treated surface of product name "SP-PET752150" manufactured by Lintec Co., Ltd.), it was heat-treated at 90°C for 1 minute to form a coating layer. Then, the release-treated surface of a light release-type release sheet (manufactured by Lintec Co., Ltd., product name "SP-PET382120") in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent was bonded onto the coating layer. Then, by curing for 7 days under the condition of 23° C. and 50% RH, the heavy release type release sheet/first adhesive layer (active energy ray curability, thickness: 100 μm)/light release type release sheet The 1st laminated body which consists of a structure was produced.

Further, in the same manner as above, a second laminate having a structure of heavy release type release sheet/second pressure-sensitive adhesive layer (active energy ray curability, thickness: 50 μm)/light release type release sheet was prepared. ..

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness meter (manufactured by Teclock Co., product name “PG-02”) according to JIS K7130.

(2) Preparation of laminate having intermediate layer (2-1) Preparation of resin composition Q Polyvinyl acetate (VAc, weight average molecular weight (Mw): 20,000, Tg: 32°C) 100 as resin (E) 100 10 parts by mass and ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate as an active energy ray-curable compound (F) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300-1CL") 10 1 part by weight of a mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (G) in a weight ratio of 1:1 (manufactured by BASF, product name "Irgacure 500"). Then, it was sufficiently stirred and diluted with methyl ethyl ketone to obtain a coating solution of the resin composition Q.

(2-2) Manufacture of Laminated Body A heavy peeling type is prepared in the same manner as the adhesive composition P described above, except that the coating solution of the resin composition Q obtained in the above step (2-1) is used and is not cured. A third laminate having a structure of release sheet/intermediate layer (curability of active energy ray, thickness: 10 μm)/light release type release sheet was prepared.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
-GPC measuring device: HLC-8020 manufactured by Tosoh Corporation
-GPC column (passed in the following order): Tosoh TSK guard column HXL-H
TSK gel GMHXL (x2)
TSK gel G2000HXL
・Measurement solvent: Tetrahydrofuran ・Measurement temperature: 40°C

(3) Production of double-sided pressure-sensitive adhesive sheet with release sheet While peeling the light release type release sheet from the first laminate obtained in the above (1), it is light from the third laminate obtained in the above (2). The release-type release sheet was peeled off, and the exposed first pressure-sensitive adhesive layer and the exposed intermediate layer were attached to each other so that they were in contact with each other, and the heavy release-type release sheet was released from the intermediate layer. Then, the light release type release sheet is peeled from the second laminate obtained in (1) above, and the exposed second pressure-sensitive adhesive layer and the above-mentioned intermediate layer are attached so as to come into contact with each other. A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained by sandwiching the double-sided pressure-sensitive adhesive sheet consisting of the pressure-sensitive adhesive layer, the intermediate layer and the second pressure-sensitive adhesive layer between two heavy release-type release sheets.

[Example 2]
A resin composition Q was prepared in the same manner as in Example 1 except that the compounding amount of the active energy ray-curable compound (F) was changed to 5 parts by mass and the compounding amount of the photopolymerization initiator (G) was changed to 0.5 part by mass. The coating solution was prepared and the 3rd laminated body was produced. A double-sided PSA sheet with a release sheet was produced in the same manner as in Example 1 except that this third laminate was used.

[Example 3]
A double-sided pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 1 except that the thickness of the intermediate layer was changed to 25 μm.

[Example 4]
In forming the intermediate layer, polyvinyl acetate (VAc, weight average molecular weight (VAc, weight average molecular weight (Mw): 20,000, Tg: 32° C.) as resin (E) was changed to 100 parts by weight, and polyvinyl acetate (VAc, weight average molecular weight ( A double-sided pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 3 except that 100 parts by mass of Mw): 200,000, Tg: 32° C.) was used.

[Example 5]
A double-sided pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 1 except that the thickness of the intermediate layer was changed to 50 μm.

[Example 6]
A coating solution of the resin composition Q was prepared in the same manner as in Example 1 except that the active energy ray-curable compound (F) and the photopolymerization initiator (G) were not blended to prepare a third laminate. A double-sided PSA sheet with a release sheet was produced in the same manner as in Example 1 except that this third laminate was used.

[Example 7]
A coating solution of the resin composition Q in the same manner as in Example 1 except that the amount of the active energy ray-curable compound (F) was changed to 30 parts by mass and the amount of the photopolymerization initiator (G) was changed to 3 parts by mass. Was prepared to prepare a third laminate. A double-sided PSA sheet with a release sheet was produced in the same manner as in Example 1 except that this third laminate was used.

[Comparative Example 1]
While peeling the light release type release sheet from the first laminate obtained in (1) of Example 1, a light release type release sheet was obtained from the second laminate obtained in (1) of Example 1. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, which are peeled and exposed, are attached to each other so that they are in contact with each other, and two pressure-sensitive adhesive layers including the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are provided. A pressure-sensitive adhesive sheet sandwiched between the heavy release-type release sheets of A double-sided pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive sheet was used.

[Comparative Example 2]
The light release type release sheet was released from the first laminate obtained in (1) of Example 1, and the exposed first adhesive layer had a polyethylene terephthalate film (thickness: 12 μm, Tg: 80 degreeC) was stuck. Then, the light release type release sheet was peeled from the second laminate obtained in (1) of Example 1 and attached so that the exposed second adhesive layer and the polyethylene terephthalate film were in contact with each other. In addition, a double-sided pressure-sensitive adhesive sheet with a release sheet obtained by sandwiching a double-sided pressure-sensitive adhesive sheet consisting of a first pressure-sensitive adhesive layer, an intermediate layer (polyethylene terephthalate film) and a second pressure-sensitive adhesive layer between two heavy release-type release sheets. Obtained.

[Test Example 1] (Measurement of glass transition temperature)
The glass transition temperature (Tg) of the intermediate layer produced and used in Examples and Comparative Examples was raised by a differential scanning calorimeter (manufactured by TA Instruments Japan, product name "DSC Q2000"). -Measurement was performed at a temperature decrease rate of 20°C/min. The results are shown in Table 1.

[Test Example 2] (Measurement of Young's modulus of adhesive layer)
A plurality of double-sided pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were laminated to have a thickness of about 1000 μm, and cut into 10 mm×70 mm test pieces. Then, the Young's modulus at 23° C. and 50% RH was measured according to JIS K7161:1994. Specifically, the above test piece was set at a chuck distance of 20 mm with a universal tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon RTA-T-2M"), and then pulled at a speed of 200 mm/min. A test was performed and Young's modulus (unit: MPa) was measured. The results are shown in Table 1.

[Test Example 3] (Evaluation of step followability)
UV curable ink (manufactured by Teikoku Ink Co., product name "POS-911 Ink") on the surface of a glass plate (manufactured by NSG Precision, product name "Corning Glass Eagle XG", length 90 mm x width 50 mm x thickness 0.5 mm). ) Was screen-printed in a frame shape (outer shape: length 90 mm×width 50 mm, width 5 mm). Next, ultraviolet rays are irradiated (80 W/cm ² , metal halide lamp 2 lights, lamp height 15 cm, belt speed 10 to 15 m/min) to cure the printed ultraviolet curable ink, and a step due to printing (high step height) A glass plate with steps having a thickness of 60 μm) was prepared.

The release sheet on the second pressure-sensitive adhesive layer (thickness: 50 μm) side was peeled off from the double-sided pressure-sensitive adhesive sheet with release sheet obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was replaced with polyethylene terephthalate (PET) having an easy-adhesion layer. ) A film (manufactured by Toyobo Co., Ltd., product name “PET A4300”, thickness: 100 μm) was attached to an easy-adhesion layer. Then, the release sheet on the side of the first pressure-sensitive adhesive layer (thickness 100 μm) was peeled off to expose the pressure-sensitive adhesive layer. Then, using a laminator (manufactured by Fuji Plastics Co., Ltd., product name "LPD3214"), the above laminate was laminated on the above stepped glass plate so that the pressure-sensitive adhesive layer covered the entire frame-shaped printing surface. After that, autoclave treatment was performed for 30 minutes at 50° C. and 0.5 MPa. At this stage, the double-sided pressure-sensitive adhesive sheet (particularly in the vicinity of the step due to the printing layer) was visually checked for bubbles. As a result, those having no bubbles were evaluated as ⊚, those having 10 or less bubbles were evaluated as ○, and those having more than 10 bubbles were evaluated as × (evaluation of initial step followability). The results are shown in Table 1.

Next, the double-sided pressure-sensitive adhesive sheet was cured by irradiating the double-sided pressure-sensitive adhesive sheet with ultraviolet rays through the PET film under the following ultraviolet ray irradiation conditions.
<UV irradiation conditions>
・Using UV conveyor device manufactured by Eye Graphics ・Illuminance 200 mW/cm ² , light intensity 1000 mJ/cm ²
・Uses "UVPF-36" manufactured by iGraphics for UV illuminance and photometer

The laminate having the double-sided pressure-sensitive adhesive sheet cured as described above was stored under conditions of high temperature and high humidity of 85° C. and 85% RH for 72 hours. Then, it was visually confirmed whether or not there were bubbles in the double-sided pressure-sensitive adhesive sheet (especially in the vicinity of the step due to the printing layer). As a result, the case where there were no bubbles was evaluated as ⊚, the case where the number of bubbles was 10 or less was evaluated as ○, and the case where there were more than 10 cells was evaluated as × (evaluation of step followability under high temperature and high humidity conditions). .. In the pressure-sensitive adhesive sheet of Example 6, the number of bubbles was 10 or less, but delamination between the pressure-sensitive adhesive layer and the intermediate layer was observed near the step (evaluation: Δ). The results are shown in Table 1.

[Test Example 4] (Evaluation of workability)
<Method A>
The double-sided pressure-sensitive adhesive sheets with release sheets obtained in Examples and Comparative Examples were cut by an automatic cutting machine (manufactured by Ogino Seisakusho, product name “Super Cutter OSS-PN1 type NL”). This cutting was performed 10 times. The cut surface (length: 100 mm) of the pressure-sensitive adhesive sheet after cutting was visually confirmed, and the workability was evaluated according to the following criteria. The results are shown in Table 1.
⊚: The adhesive did not squeeze out in 10 out of 10 times.
◯: The adhesive did not squeeze out 5 to 9 times out of 10 times.
Δ: The adhesive did not squeeze out 1 to 4 times out of 10 times.
X: The adhesive was squeezed out in every 10 out of 10 times.

<Method B>
The double-sided pressure-sensitive adhesive sheets with release sheets obtained in Examples and Comparative Examples were cut into 100 mm length×100 mm width. The cut double-sided pressure-sensitive adhesive sheet with a release sheet is placed on a horizontal table with the release sheet on the second pressure-sensitive adhesive layer side (thickness 50 μm) facing upward, and the first pressure-sensitive adhesive layer ( The release sheet having a thickness of 100 μm) was fixed to the table with an adhesive.

Next, a blade of a cutter knife was inserted to the front of the lowermost release sheet (the position where the first pressure-sensitive adhesive layer is cut) so as to vertically cut at a position with a width of 50 mm. After that, of the divided release sheet on the front surface side, only one side thereof was removed. Thereby, a double-sided pressure-sensitive adhesive sheet was obtained in which half of the surface was covered with the release sheet and the other half had the second pressure-sensitive adhesive layer exposed.

Further, an adhesive tape (manufactured by Lintec Co., product name “PET50(A)PL Shin 8LK”) cut into 100 mm length×100 mm width was attached to the double-sided pressure-sensitive adhesive sheet so that the pressure-sensitive adhesive surface was in contact with the double-sided pressure-sensitive adhesive sheet. It was stuck on the entire surface. In this bonding, sufficient pressure was applied from above the adhesive tape so that no bubbles remained at the interface between the adhesive surface and the double-sided adhesive sheet.

Finally, the attached adhesive tape was peeled off from the double-sided adhesive sheet. As a result, the double-sided PSA sheet in the part where the release sheet remained on the surface remains on the lowermost release sheet, and the double-sided PSA part in which the second adhesive layer was exposed is the best together with the adhesive tape. It was removed from the underlying release sheet. This work was performed 10 times. The cross-section (length: 100 mm) of the double-sided PSA sheet thus appeared was visually confirmed, and the workability was evaluated according to the following criteria. The results are shown in Table 1.
⊚: The adhesive did not squeeze out in 10 out of 10 times.
◯: The adhesive did not squeeze out 5 to 9 times out of 10 times.
Δ: The adhesive did not squeeze out 1 to 4 times out of 10 times.
X: The adhesive was squeezed out in every 10 out of 10 times.

As can be seen from Table 1, the double-sided pressure-sensitive adhesive sheets obtained in the examples were excellent in step-following property under initial conditions and high temperature and high humidity conditions, and also had good processability.

The double-sided pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding a protective panel having a step and a desired display member constituting member.

1... Double-sided PSA sheet with release sheet 2... Double-sided PSA sheet 2'... Cured double-sided PSA sheet 21... First PSA layer 22... Second PSA layer 23... Intermediate layer 31, 32... Release sheet 4... Display Body 51... First display body constituent member 52... Second display body constituent member 6... Printing layer

Claims (7)

One display member,
Other display member,
A display body obtained from a double-sided pressure-sensitive adhesive sheet, wherein the one display body constituent member and the other display body constituent member are bonded to each other,
The one display member constituting member is a glass plate, a plastic plate, or a laminate including a glass plate or a plastic plate, which has a step on at least the surface on the side to be bonded,
The other display member is a display module or a laminate including the display module,
The double-sided adhesive sheet,
A first pressure-sensitive adhesive layer as an outer layer on one surface side,
A second pressure-sensitive adhesive layer as an outer layer on the other surface side;
An intermediate layer located between the first adhesive layer and the second adhesive layer,
The glass transition temperature of the intermediate layer is 20 ° C. or higher and 60° C. or lower,
A Young's modulus of the double-sided pressure-sensitive adhesive sheet is 0.01 MPa or more and 50 MPa or less. The ratio of the thickness of the intermediate layer to the total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is 0.05 or more and 2 or less. The display according to item 1 . The display according to claim 1 or 2 , wherein the double-sided pressure-sensitive adhesive sheet has a total thickness of 50 µm or more and 600 µm or less. A method of manufacturing a display body comprising: one display body constituent member; another display body constituent member; and a double-sided adhesive sheet for laminating the one display body constituent member and the other display body constituent member to each other. There
The one display member constituting member is a glass plate, a plastic plate, or a laminate including a glass plate or a plastic plate, which has a step on at least the surface on the side to be bonded,
The other display member is a display module or a laminate including the display module,
Between the first pressure-sensitive adhesive layer as an outer layer on one surface side, the second pressure-sensitive adhesive layer as an outer layer on the other surface side, and between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The intermediate layer is located, the intermediate layer has a glass transition temperature of 20° C. or higher and 60° C. or lower, and a Young's modulus of 0.01 MPa or higher and 50 MPa or lower. via the double-sided pressure-sensitive adhesive sheet second adhesive layer is an active energy ray-curable, the formed by pasting a as one of the display components and the other display-constituting member to form a laminate,
A method for producing a display body, comprising irradiating the double-sided pressure-sensitive adhesive sheet of the laminate with an active energy ray to cure the double-sided pressure-sensitive adhesive sheet. A method of manufacturing a display body comprising: one display body constituent member; another display body constituent member; and a double-sided adhesive sheet for laminating the one display body constituent member and the other display body constituent member to each other. There
The one display member constituting member is a glass plate, a plastic plate, or a laminate including a glass plate or a plastic plate, which has a step on at least the surface on the side to be bonded,
The other display member is a display module or a laminate including the display module,
Between the first pressure-sensitive adhesive layer as an outer layer on one surface side, the second pressure-sensitive adhesive layer as an outer layer on the other surface side, and between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The intermediate layer has a glass transition temperature of 20° C. or higher and 60° C. or lower, a Young's modulus of 0.01 MPa or higher and 50 MPa or lower, and the intermediate layer has an active energy ray curable property. in it via the double-sided pressure-sensitive adhesive sheet, the formed by pasting a as one of the display components and the other display-constituting member to form a laminate,
A method for producing a display body, comprising irradiating the double-sided pressure-sensitive adhesive sheet of the laminate with an active energy ray to cure the double-sided pressure-sensitive adhesive sheet. A method of manufacturing a display body comprising: one display body constituent member; another display body constituent member; and a double-sided adhesive sheet for laminating the one display body constituent member and the other display body constituent member to each other. There
The one display member constituting member is a glass plate, a plastic plate, or a laminate including a glass plate or a plastic plate, which has a step on at least the surface on the side to be bonded,
The other display member is a display module or a laminate including the display module,
Between the first pressure-sensitive adhesive layer as an outer layer on one surface side, the second pressure-sensitive adhesive layer as an outer layer on the other surface side, and between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The intermediate layer is positioned, the intermediate layer has a glass transition temperature of 20° C. or higher and 60° C. or lower, and a Young's modulus of 0.01 MPa or higher and 50 MPa or lower, the first pressure-sensitive adhesive layer, and the second adhesive layer and the intermediate layer via a double-sided pressure-sensitive adhesive sheet is an active energy ray-curable, the laminate comprising pasted and the other of the display components as the one of the display components Made,
A method for producing a display body, comprising irradiating the double-sided pressure-sensitive adhesive sheet of the laminate with an active energy ray to cure the double-sided pressure-sensitive adhesive sheet. The method for producing a display body according to claim 5 , wherein the intermediate layer contains a resin having a glass transition temperature of 20 ° C. or higher and 60° C. or lower, and an active energy ray-curable component.

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