JP7090128B2 - Double-sided adhesive sheet, display body and manufacturing method of display body - Google Patents

Description

The present invention relates to a double-sided pressure-sensitive adhesive sheet suitable for bonding display body constituent members, a display body obtained by using the double-sided pressure-sensitive adhesive sheet, and a method for manufacturing the same.

In recent years, various mobile electronic devices such as smartphones and tablet terminals are equipped with 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 popular as a touch panel. In a display as described above, a protective panel is usually provided on the surface side of the display module.

Here, a gap is provided between the protective panel and the display body module so that the deformed protective panel does not collide with the display body 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 light reflection loss 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 the display has a large return loss. There is a problem that the image quality is deteriorated.

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 the adhesive layer. However, a frame-shaped print 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 light reflection loss. Therefore, the pressure-sensitive adhesive layer is required to have a step followability.

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

Japanese Unexamined Patent Publication No. 2010-97070

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 processability is deteriorated. For example, when the pressure-sensitive adhesive sheet is cut, there arises a problem that the pressure-sensitive adhesive layer is crushed, the pressure-sensitive adhesive protrudes from the cut surface, and the pressure-sensitive adhesive adheres to the blade.

The present invention has been made in view of such an actual situation, and is a double-sided pressure-sensitive adhesive sheet having excellent step followability and good workability, 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 has a first pressure-sensitive adhesive layer as an outer layer on one side, a second pressure-sensitive adhesive layer as an outer layer on the other side, and the first. The adhesive layer is provided with an intermediate layer located between the pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, and the glass transition temperature of the intermediate layer is 0 ° C. or higher and 60 ° C. or lower. A sheet is provided (Invention 1).

According to the above invention (Invention 1), when the glass transition temperature of the intermediate layer is in the above range, the intermediate layer becomes hard to some extent at room temperature, thereby improving the film strength of the entire double-sided pressure-sensitive adhesive sheet and processing it. The sex becomes good. Further, when the glass transition temperature of the intermediate layer is in the above range, the intermediate layer is softened by heating, whereby the entire double-sided adhesive sheet becomes flexible and has excellent step followability.

In the above invention (Invention 1), it is preferable that the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are active energy ray-curable (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the intermediate layer is active energy ray curable (Invention 3).

In the above invention (Invention 3), it is preferable that the intermediate layer contains a resin having a glass transition temperature of 0 ° C. or higher and 60 ° C. or lower and an active energy ray-curable component (Invention 4).

The double-sided pressure-sensitive adhesive sheet according to the above inventions (Inventions 1 to 4) preferably has a Young's modulus of 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 pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.05 or more and 2 or less. It is preferable (Invention 6).

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

Secondly, the present invention includes two release sheets and the double-sided pressure-sensitive adhesive sheets (inventions 1 to 7) sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. Provided is a double-sided pressure-sensitive adhesive sheet with a characteristic release sheet (Invention 8).

Thirdly, in the present invention, one display body component having at least a step on the surface on the side to be bonded, another display body component, the one display body component, and the other display body component. Provided is a display body characterized by being obtained from the double-sided pressure-sensitive adhesive sheets (Inventions 1 to 7) in which and are bonded to each other (Invention 9).

Fourth, in the present invention, one display body component having at least a step on the surface on the side to be bonded, another display body component, the one display body component, and the other display body component. (Invention 10) is provided with a display body provided with a cured double-sided pressure-sensitive adhesive sheet obtained by curing the double-sided pressure-sensitive adhesive sheet (Invention 2 and 3).

Fifth, in the present invention, one display body constituent member and another display body constituent member are bonded to each other via the double-sided adhesive sheet (Invention 2 and 3) to produce a laminated body, and the laminated body is produced. Provided is a method for manufacturing a display body, which comprises irradiating the double-sided pressure-sensitive adhesive sheet with active energy rays to cure the double-sided pressure-sensitive adhesive sheet (Invention 11).

The double-sided adhesive sheet according to the present invention has excellent step followability and workability. Further, in the display body according to the present invention, the double-sided adhesive sheet having excellent step followability suppresses the occurrence of gaps, floats, etc. in the vicinity of the step. Further, according to the method for manufacturing a display body according to the present invention, it is possible to obtain a display body in which gaps, floating and the like are suppressed in the vicinity of 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]
FIG. 1 shows a cross-sectional view of a double-sided pressure-sensitive adhesive sheet according to an embodiment of the present invention.
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 side and a second pressure-sensitive adhesive layer 22 as an outer layer on the other side. And an intermediate layer 23 located between the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22.

The double-sided 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, and this laminated body is double-sided adhesive with the release sheet. It is called sheet 1. However, the release sheet 31 and / or the release sheet 32 may not necessarily be laminated on the double-sided adhesive sheet 2. The peeling surface of the release sheet in the present specification refers to a surface having peelability in the release sheet, and includes both a surface subjected to peeling treatment and a surface exhibiting peelability even without peeling 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 is in contact with the peeling surface of the release sheet 31. The second pressure-sensitive adhesive layer 22 is in contact with the peeling surface of the peeling sheet 32, but is not limited thereto. Further, in the present embodiment, the intermediate layer 23 and the first pressure-sensitive adhesive layer 21 are directly laminated, and the intermediate layer 23 and the second pressure-sensitive adhesive layer 22 are directly laminated, but the present invention is limited to this. It's 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 the range, the intermediate layer 23 becomes hard to some extent at room temperature. As a result, the film strength of the entire double-sided adhesive sheet 2 is also improved, and the workability is improved. For example, when the double-sided adhesive sheet 1 with a release sheet is cut, the double-sided adhesive sheet 2 itself is less likely to be crushed, and the presence of the intermediate layer 23 makes it relatively easy to crush the first adhesive layer 21 and the second. Since the cross-sectional area of the pressure-sensitive adhesive layer 22 is also small, it is possible to prevent problems such as the pressure-sensitive adhesive protruding from the cut surface and the pressure-sensitive adhesive adhering to the blade.

On the other hand, when the glass transition temperature of the intermediate layer 23 is in the above range, the intermediate layer 23 is softened by heating, and the entire double-sided pressure-sensitive adhesive sheet 2 becomes excellent in flexibility. Therefore, when the double-sided adhesive sheet 2 is attached to an adherend having a step (for example, a display body constituent member), the double-sided adhesive sheet 2 is heated to allow the double-sided adhesive sheet 2 to follow the step (initial step). It has excellent followability) and suppresses the occurrence of gaps, floats, etc. in the vicinity of 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. The glass transition temperature is preferably 60 ° C. or lower, and particularly preferably 40 ° C. or lower. The method for measuring the glass transition temperature in the present specification is as shown in a test example described later.

Here, as will be described later, when the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are active energy ray-curable, preferably 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 is excellent not only in the initial step-following property but also in the step-following property under high temperature and high humidity conditions. For example, even when a laminate provided with an adherend having a step (for example, a display body component) and a double-sided adhesive sheet 2 is placed at 85 ° C. and 85% RH for 72 hours, air bubbles and floats are formed in the vicinity of the step. , Peeling, etc. are suppressed. Here, the cured (cured state) 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 irradiation with further active energy rays. The presence or absence of further formation of the higher-order structure can be determined, for example, by the amount of change in the gel fraction. Specifically, when the amount of increase in the gel fraction is small (preferably 5% or less) due to further irradiation with active energy rays, it can be said that the gel is in a cured state.

1. 1. The first pressure-sensitive adhesive layer and the 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 non-active energy ray curable, but it is preferable that at least one of them is active energy ray curable, and the first pressure-sensitive adhesive layer 21 and the second adhesive layer 21 and the second. It is more preferable that all of the pressure-sensitive adhesive layers 22 are active energy ray-curable. As a result, the double-sided 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 constituting the first pressure-sensitive adhesive layer and the pressure-sensitive adhesive constituting 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 active energy ray non-curable, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be, for example, an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive. Any of a pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyvinyl ether-based pressure-sensitive adhesive, and the like may be used. Further, the pressure-sensitive adhesive may be an emulsion type, a solvent type or a solvent-free type, and may be either a crosslinked type or a non-crosslinked type. Among the above, an acrylic adhesive is preferable.

The active energy ray non-curable pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive after being cured by the active energy rays (a pressure-sensitive 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 constituting the pressure-sensitive adhesive layer is an active energy ray-curable pressure-sensitive adhesive (active energy ray). 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, and other than that, an active energy ray-curable monomer, It may contain any of oligomers and polymers, or a mixture thereof.

The active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive composition containing the (meth) acrylic acid ester polymer (A) and the active energy ray-curable compound (B) (hereinafter referred to as "sticky composition P"). In some cases), it is preferable that it is obtained from. The adhesive composition P preferably further contains a cross-linking agent (C). In this case, the obtained pressure-sensitive adhesive comprises a pressure-sensitive adhesive obtained by cross-linking the (meth) acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P with a cross-linking agent (C) (active energy ray-curable compound (active energy ray-curable compound). B) is preferably present in the pressure-sensitive adhesive layer without polymerization). In addition, in this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. In addition, the concept of "polymer" shall be 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 an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer, thereby achieving preferable adhesiveness. Can be expressed. Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, and n- (meth) acrylic acid. Butyl, (meth) acrylic acid n-pentyl, (meth) acrylic acid n-hexyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid isooctyl, (meth) acrylic acid n-decyl, (meth) acrylic acid Examples thereof include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. Among them, 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 from the viewpoint of further improving the adhesiveness. .. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains 40% by mass or more of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as the monomer unit constituting the polymer. In particular, it is preferably contained in an amount of 50% by mass or more, and more preferably 60% by mass or more. If the (meth) acrylic acid alkyl ester is contained in an amount of 40% by mass or more, the (meth) acrylic acid ester polymer (A) can be imparted with suitable adhesiveness. Further, the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms of the alkyl group is preferably contained in an amount of 90% by mass or less, particularly preferably 80% by mass or less, and further contained 70% by mass or less. Is preferable. By setting the content of the (meth) acrylic acid alkyl ester to 90% by mass or less, a desired amount of other monomer components can be introduced into the (meth) acrylic acid ester polymer (A).

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

The reactive functional group-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer includes a monomer having a hydroxyl group in the molecule (monomer containing a hydroxyl group) and a carboxyl in the molecule. Preferred examples thereof include a monomer having a group (monomer containing a carboxyl group) and a monomer having an amino group in the molecule (monomer containing an amino group). Among these, a hydroxyl group-containing monomer having excellent reactivity with the cross-linking agent (C) and having 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). ) Acrylic acid (meth) Acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylic acid can be mentioned. Among them, 2-hydroxyethyl (meth) acrylate in the obtained (meth) acrylic acid ester polymer (A) from the viewpoint of reactivity with the cross-linking agent (C) of the hydroxyl group and copolymerizability with other monomers. Alternatively, 4-hydroxybutyl (meth) acrylate is preferred. 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. Of these, 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 cross-linking 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. The nitrogen atom-containing monomer described later is excluded from this 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 thereof is preferably 3% by mass or more as a lower limit, and particularly 10% by mass. % Or more, more preferably 15% by mass or more. The content thereof is preferably 35% by mass or less as an upper limit value, particularly preferably 30% by mass or less, and further preferably 25% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer in the above amount as a monomer unit, a predetermined amount of hydroxyl groups remains in the obtained pressure-sensitive adhesive. Hydroxyl groups are hydrophilic groups, and when such hydrophilic groups are present in a predetermined amount of the pressure-sensitive adhesive, even if the pressure-sensitive adhesive is placed under high-temperature and high-humidity conditions, it penetrates into the pressure-sensitive adhesive under the high-temperature and high-humidity conditions. The compatibility with the water is good, and as a result, the whitening of the adhesive when returned to normal temperature and humidity is suppressed (excellent in moisture and heat whitening resistance).

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

When the adherend is a material that is easily adversely affected by acid, for example, a transparent conductive film, a metal wiring, or the like, the (meth) acrylic acid ester polymer (A) is used as a monomer unit constituting the polymer. , It is preferable not to contain a carboxyl group-containing monomer. Thereby, for example, it is possible to suppress the corrosion of the transparent conductive film and the metal wiring and the change of the resistance value of the transparent conductive film.

Here, "does not contain a monomer having a carboxyl group" means that a monomer having a carboxyl group is substantially not contained, and in addition to containing no monomer containing a carboxyl group, a transparent conductive film having a carboxyl group or a metal. It is permissible to contain 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 in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, as a monomer unit. 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 (monomer containing an alicyclic structure) as a monomer unit constituting the copolymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the monomer in the polymer widens the distance between the polymers, and the obtained pressure-sensitive adhesive can be made excellent in flexibility. .. Therefore, the pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P by using the alicyclic structure-containing monomer as the constituent monomer unit in the (meth) acrylic acid ester polymer (A) has an initial step-following property. It will be excellent.

The alicyclic structure carbon ring in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond as a part. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as bicyclic or tricyclic. The alicyclic structure is a polycyclic alicyclic structure (from the viewpoint of widening the distance between the obtained (meth) acrylic acid ester polymers (A) and effectively exerting the flexibility of the pressure-sensitive adhesive. Polycyclic structure) is preferable. Further, in consideration of the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. Further, from the viewpoint of effectively exerting the flexible action of the pressure-sensitive adhesive as described above, the number of carbon atoms in the alicyclic structure (refers to all the carbon atoms in the portion forming the ring, and 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, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but is preferably 15 or less, and particularly preferably 10 or less, from the viewpoint of compatibility as described above.

Examples of the alicyclic structure include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantan skeleton, isobornyl skeleton, cycloalcan skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononan skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.). , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), Norbornen skeleton, Norbornadiene skeleton, Cuban skeleton, Basquetan skeleton, Hausan skeleton, Spiro skeleton, etc. Those containing a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), adamantan skeleton (carbon number of alicyclic structure: 10) or isobornyl skeleton (carbon number of alicyclic structure: 7) are preferable, and particularly Those containing an isobornyl skeleton are preferable.

As the alicyclic structure-containing monomer, a (meth) acrylic acid ester monomer containing the above skeleton is preferable, and specifically, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth). Examples thereof include adamantyl acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, etc. Among them, (meth) acrylic which exhibits more excellent durability. Dicyclopentanyl acid, adamantyl (meth) acrylate or isobornyl (meth) acrylate are preferred, and isobornyl (meth) acrylate is particularly preferred. These may be used individually by 1 type, or may be used in combination of 2 or more type.

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 monomer is preferably 5% by mass or more, particularly preferably 8% by mass or more, and further preferably 10% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 40% by mass or less of an alicyclic structure-containing monomer, and particularly 30% by mass or less, as a monomer unit constituting the polymer. It is 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.

It is also preferable that the (meth) acrylic acid ester polymer (A) contains a monomer having a nitrogen atom in the molecule (nitrogen atom-containing monomer) as a monomer unit constituting the copolymer. By allowing a nitrogen atom-containing monomer to exist in the polymer as a constituent unit, the reaction between the acrylic acid ester copolymer (A) and the cross-linking agent (C) can be promoted, or the pressure-sensitive adhesive can be imparted with polarity to provide a 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, a monomer having a nitrogen-containing heterocycle, and the like, and 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) acryloylpiperidin, and N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloyl aziridine, aziridinyl ethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholin, which exhibits more excellent adhesive strength, is preferable, and N-acryloylmorpholin is particularly preferable.

Examples of nitrogen atom-containing monomers other than the above-mentioned nitrogen-containing heterocycles include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, and 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-vinylcaprolactum, dimethylaminoethyl (meth) acrylate and the like 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) contains 1 nitrogen atom-containing monomer. It is preferably contained in an amount of% by mass or more, particularly preferably 2% by mass or more, and further preferably 5% by mass or more. Further, 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 preferably contained in an amount of 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 containing no 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, styrene and the like. 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 weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 100,000 or more as a lower limit, 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 equal to or higher than the above, the film strength of the obtained pressure-sensitive adhesive becomes relatively high, and the step tracking under high temperature and high humidity conditions is achieved. Sex improves. 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. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

In the 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 of the pressure-sensitive adhesive layer has adhesiveness before irradiation with the active energy ray, and is cured by irradiating the adherend with the active energy ray after being attached to the adherend to improve the adhesive strength. It is a property.

Here, when the pressure-sensitive adhesive composition P contains the cross-linking agent (C) described later in addition to the active energy ray-curable compound (B), the above-mentioned (meth) acrylic is used in the obtained pressure-sensitive adhesive layer. 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 polymerization). Presumed. Then, when the pressure-sensitive 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 compound (B) is (meth) acrylic acid. It is presumed that the ester polymer (A) is entangled with the crosslinked structure (three-dimensional network structure), so that the pressure-sensitive adhesive layer is cured. Since the pressure-sensitive adhesive having such a high-order structure has high cohesive force and exhibits a relatively high elastic modulus, double-sided pressure-sensitive adhesive having a cured first pressure-sensitive adhesive layer 21 and / or a second pressure-sensitive adhesive layer 22 as the outermost layer. The sheet 2 (corresponding to the double-sided adhesive sheet 2'after curing, which will be described later) 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 active energy rays and can obtain the above effects, and may be any of a monomer, an oligomer or a polymer, and they may be used. May be a mixture of. Among them, a polyfunctional acrylate-based monomer having an excellent compatibility with the (meth) acrylic acid ester polymer (A) and the like and having a molecular weight of less than 1000 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, and polyethylene glycol di. (Meta) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyldi (meth) acrylate, caprolactone-modified dicyclopentenyldi (meth) acrylate, ethylene oxide-modified Di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyldi (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] Bifunctional types such as fluorene; trimethylol propantri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylol. Trifunctional types such as propanetri (meth) acrylate, tris (acryloxyethyl) isocyanurate, ε-caprolactone-modified tris- (2- (meth) acryloxyethyl) isocyanurate; diglycerin tetra (meth) acrylate, pentaerythritol. 4-functional type such as tetra (meth) acrylate; 5-functional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; 6 such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Sensory type and the like can be 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-following property of the obtained pressure-sensitive adhesive. These may be used individually by 1 type and may be used in combination of 2 or more type.

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-based oligomers include polyester acrylate-based, epoxy acrylate-based, urethane acrylate-based, polyether acrylate-based, polybutadiene acrylate-based, and silicone acrylate-based.

The weight average molecular weight of the acrylate-based oligomer is preferably 50,000 or less as an upper limit value, and particularly preferably 40,000 or less. Further, the weight average molecular weight is preferably 1,000 or more as a lower limit value, 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 a (meth) acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and is used as a part of the crosslinkable functional group of the copolymer. , (Meta) can be obtained by reacting a compound having a group that reacts with an acryloyl group and a crosslinkable functional group.

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

The active energy ray-curable compound (B) may be used by selecting one from the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer and adduct acrylate-based polymer, or in combination of two or more. It can also be used in combination with other active energy ray-curable components.

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

(1-3) Crosslinking agent (C)
The adhesive composition P preferably contains a cross-linking agent (C). By containing the cross-linking agent (C), the adhesive composition P cross-links the (meth) acrylic acid ester polymer (A) to form a three-dimensional network structure, and improves the cohesive force of the obtained pressure-sensitive adhesive. It is possible to further improve the step followability under high temperature and high humidity conditions.

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), for example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an amine-based cross-linking agent, and the like. Melamine-based cross-linking agents, aziridine-based cross-linking agents, hydrazine-based cross-linking agents, aldehyde-based cross-linking agents, oxazoline-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, ammonium salt-based cross-linking 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-based cross-linking agent having excellent reactivity with the hydroxyl group. When the (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, an epoxy-based cross-linking agent having excellent reactivity with the carboxyl group is used. Is preferable. The cross-linking agent (C) may be used alone or in combination of two or more.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. , And their biurets, isocyanates, and adducts, which are reactants 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 a hydroxyl group.

Examples of the epoxy-based cross-linking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylenediamine, and ethylene glycol diglycidyl. Examples thereof include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine. Of these, 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a 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 more preferably 0.02 part by mass or more. Further, the upper limit value 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 in the above range, the cohesive force of the obtained adhesive is preferable, and the step followability of the obtained adhesive under high temperature and high humidity conditions is improved.

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

Examples of such a photopolymerization initiator (D) include benzoine, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy. -2-Phenylacetphenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (Methylthio) Phenyl] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Phenylphenone, Dichlorobenzophenone, 2-Methylanthraquinone, 2-Ethylanthraquinone, 2-Turshary-butylanthraquinone, 2-Aminoanthraquinone, 2-Methylthioxanthone, 2-Ethylthioxanthone, 2-Chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyldimethylketal, acetophenonedimethylketal, 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 value with respect to 100 parts by mass of the active energy ray-curable compound (B). In particular, it is preferably 1 part by mass or more. The upper limit is preferably 30 parts by mass or less, and particularly preferably 10 parts by mass or less.

(1-5) Various Additives The tacky composition P contains various additives usually used for acrylic pressure-sensitive adhesives, such as silane coupling agents, antistatic agents, tackifiers, and antioxidants, if desired. , Light stabilizers, softeners, fillers, refractive index adjusters and the like can be added.

The tacky 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. And diluting solvent are not included in the adhesive composition P.

(1-6) Production of Adhesive Composition The adhesive composition P produced a (meth) acrylic acid ester polymer (A) and was active with the obtained (meth) acrylic acid ester polymer (A). It can be produced by mixing with the energy ray-curable compound (B) and, if desired, adding a cross-linking 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 using a polymerization initiator, if desired. 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 of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them 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, , 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, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butylperoxyneodecanoate, t-butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

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

Once the (meth) acrylic acid ester polymer (A) is obtained, the solution of the (meth) acrylic acid ester polymer (A) is mixed with the active energy ray-curable compound (B), optionally a cross-linking agent (C), and light. By adding the polymerization initiator (D), the additive and the diluting solvent and mixing them well, the tacky composition P (coating solution) diluted with the solvent can be obtained. If any of the above components is in the form of a solid, or if precipitation occurs when the component is mixed with another component in an undiluted state, the component is used alone as a diluting solvent in advance. It may be dissolved or diluted and then mixed with other ingredients.

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

The concentration and viscosity of the coating solution prepared in this manner may be any range as long as it can be coated, and may be appropriately selected depending on the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 60% by mass. It should be noted that the addition of a diluting solvent or the like is not a necessary condition when obtaining the coating solution, and the diluting solvent may not be added as long as the adhesive composition P has a viscosity that allows 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 it is as a diluting solvent.

(1-7) Production of Adhesive The active energy ray-curable adhesive can be preferably obtained by cross-linking the adhesive composition P. Crosslinking of the adhesive composition P can usually be carried out by heat treatment. It should be noted that this heat treatment can also be used as a drying treatment for volatilizing the diluting solvent or the like from the coating film of the adhesive composition P applied to the desired object.

The heating temperature of the heat treatment is preferably 50 to 150 ° C, 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, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). If this curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, the adhesive is formed after the heat treatment is completed.

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

(2) Thickness of Adhesive Layer The thickness of the first adhesive layer 21 and the thickness of the second adhesive layer 22 are preferably 15 μm or more, and particularly preferably 30 μm or more. Further, it is preferably 50 μm or more. 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 above-mentioned effects of step followability and workability can be more satisfactorily exhibited. The thickness of the first pressure-sensitive adhesive layer 21 and the thickness of the second pressure-sensitive 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 to be attached to the adherend having a step is thicker than the other pressure-sensitive adhesive layer.

2. 2. Intermediate layer As described above, the intermediate layer 23 has a glass transition temperature of 0 ° C. or higher and 60 ° C. or lower. 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, from the viewpoint of improving the initial step followability, the glass transition temperature is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 30 ° C. or lower. ..

The intermediate layer 23 may be non-curable with active energy rays or may be 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, it is preferable that the intermediate layer 23 is also 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 adhesion strength between the pressure-sensitive adhesive layer and the intermediate layer 23 is increased, delamination is suppressed, and the step-following property of the double-sided pressure-sensitive adhesive sheet 2 under high temperature and high humidity conditions is further improved.

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

In order to obtain the intermediate layer 23 having the above glass transition temperature, the material constituting 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, it is preferable that the intermediate layer 23 is composed of a resin composition containing the resin (E) (hereinafter, may be referred to as “resin composition Q”).

(1) Resin composition (1-1) Resin (E)
When 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, the glass transition temperature of the intermediate layer 23 itself is in the above-mentioned range. It becomes easier to enter. From this point of view, the glass transition temperature of the resin (E) is particularly preferably 20 ° C. or higher, and even more preferably 30 ° C. or higher. Further, the glass transition temperature of the resin (E) is particularly preferably 50 ° C. or lower, and even more preferably 40 ° C. or lower.

Examples of the resin (E) include vinyl acetate resin and polyolefin resin, and among them, vinyl acetate resin which can make the initial step followability of the double-sided pressure-sensitive adhesive sheet 2 particularly excellent is preferable. Examples of the vinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, such as an ethylene-vinyl acetate copolymer. Can be mentioned.

The weight average molecular weight of the vinyl acetate resin is preferably 10,000 or more as a lower limit value, 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 equal to or higher than the above, the film-forming property and processability of the intermediate layer 23 are improved. The weight average molecular weight of the vinyl acetate resin is preferably 1 million or less, particularly preferably 700,000 or less, and further preferably 500,000 or less as the upper limit value. 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 preferably contained in an amount of 80% by mass or more, more preferably 80% by mass or more. The resin composition Q may be composed of only 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 95% by mass or less. It is preferably contained, more preferably 93% by mass or less, and even more preferably 90% by mass or less.

(1-2) Other Components When the intermediate layer 23 is active energy ray curable, the resin composition Q may contain the 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 type 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 value is preferably 1 part by mass or more, particularly preferably 5 parts by mass or more, and 10 parts by mass or more from the viewpoint of further improving the initial step followability. More preferred. On the other hand, the content is preferably 40 parts by mass or less, particularly preferably 30 parts by mass or less, and 20 parts by mass or less as an upper limit value from the viewpoint of not excessively lowering the glass transition temperature of the intermediate layer 23. Is more preferable.

Further, 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 value with respect to 100 parts by mass of the active energy ray-curable compound (F), particularly 1 It is preferably parts by mass or more. 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 a first pressure-sensitive adhesive layer 21 and a second pressure-sensitive adhesive layer 22 in addition to the resin (E). It is preferable to contain 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) in the pressure-sensitive adhesive. It is particularly preferable to contain a cross-linking agent for forming the cross-linked structure. The crosslinkable monomer preferably has the same functional group as the reactive functional group contained in the (meth) acrylic acid ester polymer (A), and for example, constitutes the (meth) acrylic acid ester polymer (A). 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 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 constituting 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.

In the above case, when the pressure-sensitive adhesive composition and the resin composition Q for forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are thermally cross-linked, the (meth) acrylic acid ester polymer (A) is obtained. And the crosslinkable monomer are crosslinked via the crosslinking agent (C) in the adhesive composition or the crosslinking agent in the resin composition Q, and are chemically bonded. As a result, the adhesion between the first pressure-sensitive adhesive layer 21 and the intermediate layer 23 and the second pressure-sensitive adhesive layer 22 and the intermediate layer 23 is enhanced, and the intermediate layer 23 and the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive are enhanced. Delamination is suppressed at the interface with the layer 22.

If desired, various additives such as antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive index adjusters 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 diluted solvent described later, are used. , Not included in the resin composition Q.

(1-3) Production of Resin Composition / Intermediate Layer The resin composition Q contains a 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 it. When the resin composition Q is applied, a diluting solvent is added as desired 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 it. This drying can usually be performed by heat treatment. The conditions of the heat treatment are the same as the conditions of the heat treatment when producing the above-mentioned pressure-sensitive adhesive.

When the intermediate layer 23 is non-curable with active energy rays and the resin composition Q contains the active energy ray-curable compound (F), the active energy is further increased after the above coating and drying. The resin composition Q may be cured by linear irradiation, and this may be used as the intermediate layer 23. However, in consideration of the initial step followability, the display body component having a step and another display body component are bonded to each other by the double-sided adhesive sheet 2, and then irradiated with active energy rays to obtain the intermediate layer 23 (. It is preferable to cure the constituent resin composition Q).

(2) Thickness of the intermediate layer The ratio of the thickness of the intermediate layer 23 to the total thickness of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is preferably 0.01 or more, and is particularly 0. It is preferably 0.05 or more, and more preferably 0.15 or more. 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 above-mentioned effects of step tracking and workability are more satisfactorily exhibited. The thickness of each layer shall be 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. 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 above-mentioned effects of step followability and workability can be more satisfactorily exhibited.

3. 3. Peeling Sheets The peeling sheets 31 and 32 protect the adhesive surface in contact with the double-sided adhesive sheet 2 until the time of use, and are peeled off when the double-sided adhesive sheet 2 is used. In the double-sided adhesive sheet 1 with a release sheet according to the present 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, and polybutylene. Telephthalate 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. In addition, these crosslinked films are also used. Further, these laminated films may be used.

It is preferable that the peeling surface of the peeling sheets 31 and 32 (particularly the surface in contact with the double-sided adhesive sheet 2) is subjected to a peeling 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. Of the release sheets 31 and 32, it is preferable that one of the release sheets 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 small 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 characteristics of the pressure-sensitive adhesive sheet The total thickness of the double-sided pressure-sensitive adhesive sheet 2 is preferably 50 μm or more, particularly preferably 100 μm or more, and further preferably 150 μm or more. 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 adhesive sheet 2 is within the above range, the above-mentioned effects of step followability and workability can be more satisfactorily exhibited.

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 as the lower limit value. When the Young's modulus is at least the above lower limit value, the film 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 Young's modulus is preferably 100 Mpa or less, particularly preferably 50 Mpa or less, and further preferably 20 Mpa or less as the upper limit value. When the Young's modulus is not more than the above upper limit value, the flexibility of the double-sided adhesive sheet 2 becomes good, and the initial step followability of the double-sided adhesive sheet 2 becomes more excellent. The method for measuring Young's modulus is as shown in a test example described later.

5. Production of Double-sided Adhesive Sheet As an example of production of the double-sided adhesive sheet 1 with a release sheet, a coating liquid of the adhesive composition P is applied to the release surface of one of the release sheets 31, and heat treatment is performed to obtain an adhesive composition. The material P is thermally crosslinked to form a coating layer to obtain a release sheet 31 with a coating layer of the adhesive composition P. Further, the coating liquid of the adhesive composition P is applied to the peeling surface of the other release sheet 32, heat-treated to heat-crosslink the adhesive composition P to form a coating layer, and the adhesive composition is formed. A release sheet 32 with a coating layer of the object P is obtained. Further, the coating liquid of the resin composition Q is applied to the peeling surface of another peeling sheet and dried to obtain a peeling sheet with the intermediate layer 23.

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 so that both layers are in contact with each other, and the release sheet is peeled from the intermediate layer 23. Next, the intermediate layer 23 and the release sheet 32 with the coating layer of the adhesive composition P are bonded so that both layers are in contact with each other. If a curing period is required, the curing period is set, and if the curing period is not required, the coated layer of the above-mentioned laminated adhesive composition P is the first adhesive layer 21 and the other adhesive layer. The coating layer of the sex composition P becomes the second pressure-sensitive adhesive layer 22. As a result, the double-sided pressure-sensitive adhesive sheet 1 with a peel-off sheet is obtained, in which the double-sided pressure-sensitive adhesive sheet 2 composed of 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. .. The curing of the coating layer of the adhesive composition may be performed after the coating layers of the adhesive composition are bonded to form three layers as described above, or may be performed before bonding.

As a method for applying the coating liquid of the adhesive composition P and the coating liquid 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 and the like are used. can do.

Since the double-sided adhesive sheet 1 with a release sheet according to the present embodiment has good workability, when the double-sided adhesive sheet 1 with a release sheet is cut or the like, the adhesive squeezes out from the cut surface and the adhesive is applied to the blade. It is possible to prevent problems such as sticking.

[Display body]
As shown in FIG. 2, the display body 4 according to the present embodiment has a first display body constituent member 51 (one display body constituent member) having a step on at least the surface on the side to be bonded, and a second display body constituent member 51. A display body component 52 (another display body component) and a double-sided adhesive sheet 2 located between them and for bonding the first display body component 51 and the second display body component 52 to each other. Be prepared for it. 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 adhesive sheet 2 side, and specifically, has a step due to the print layer 6. ..

When any one 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 is peeled off as described above. The double-sided adhesive sheet 2 of the double-sided adhesive sheet 1 with a sheet is cured by irradiation with active energy rays to obtain a double-sided adhesive sheet 2'after curing. Here, the active energy beam 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, which are easy to handle, are particularly preferable.

The 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 about 50 to 1000 mW / cm ² . The amount of light is preferably 50 to 10000 mJ / cm ² , more preferably 80 to 5000 mJ / cm ² , and particularly preferably 200 to 2000 mJ / cm ² . On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 quad.

To irradiate the double-sided adhesive sheet 2 with active energy rays, the first display body constituent member 51 and the second display body constituent member 52 are bonded to each other by the double-sided adhesive sheet 2, and then the first display body constituent member 51 is applied. And, among the second display body constituent members 52, it is preferable to perform the operation through the member that transmits the active energy rays.

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 compounds (F) in the intermediate layer 23 polymerizes and cures. The double-sided adhesive sheet 2'after curing, which is cured by irradiation with active energy rays, has very excellent step followability under high temperature and high humidity. Further, 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 active energy ray-curable, the active energy ray-curable by irradiation with active energy rays. Since the sex compound (B) and the active energy ray-curable compound (F) react with each other and chemically bond with each other, the adhesion between the active energy ray-curable pressure-sensitive adhesive layer and the intermediate layer 23 is enhanced, and the adhesion is improved. Delamination is suppressed at the interface between the agent layer and the intermediate layer 23.

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

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

The glass plate is not particularly limited, and for example, chemically strengthened glass, non-alkali glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and 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.

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

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

Examples of the optical member include a shatterproof film, a polarizing plate (polarizing film), a polarizing element, a retardation plate (phase difference film), a viewing angle compensation film, a brightness improving film, a contrast improving film, a liquid crystal polymer film, and a diffusion film. , Semi-transmissive reflective film, transparent conductive film and the like. Examples of the shatterproof film include a hard coat film in which a hard coat layer is formed on one side of a base film.

The material constituting the print layer 6 is not particularly limited, and a known material for printing is used. The thickness of the print 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 higher than the above, it is possible to sufficiently secure concealment such as making the electrical wiring invisible to the viewer. The upper limit 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. When the upper limit value is not more than the above, it is possible to prevent deterioration of the step followability of the double-sided adhesive sheet 2 with respect to the print layer 6.

In order to manufacture the display body 4, as an example, one of the release sheets 31 of the double-sided adhesive sheet 1 with a release sheet is peeled off, and the exposed adhesive surface of the double-sided adhesive sheet 2 is removed from the exposed adhesive surface of the first display body component 51. Is bonded to the surface on the side where the print layer 6 is present.

After that, the other release sheet 32 is peeled off from the double-sided adhesive sheet 1 with the release sheet, and the exposed adhesive surface of the double-sided adhesive sheet 2 and the second display body constituent member 52 are bonded to each other. Further, as another example, the bonding order of the first display body constituent member 51 and the second display body constituent member 52 may be changed.

In performing the above bonding, the double-sided adhesive sheet 1 with a release sheet is heated to soften the intermediate layer 23 in the double-sided 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 ℃ or more and 50 ℃ or less. By the above heating, the entire double-sided adhesive sheet 2 has excellent flexibility and excellent initial step followability, so that it is possible to suppress the occurrence of gaps and floats in the vicinity of the step due to the print layer 6.

Next, when any one 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 active energy ray is applied to the double-sided pressure-sensitive adhesive sheet 2. Irradiate to cure the active energy ray curable layer.

In the above display body 4, at least one 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. If this is the case, the double-sided 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), it is possible to prevent bubbles, floating, peeling, and the like from occurring in the vicinity of the step. Further, 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 cured by irradiation with active energy rays, they are intermediate with the pressure-sensitive adhesive layer. Delamination at the interface with the layer 23 is also suppressed.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to 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 1 with a release sheet may be omitted, or a desired optical member may be laminated in place of the release sheet 31 and / or 32. Further, another layer may be present between the first pressure-sensitive adhesive layer 21 and / or the second pressure-sensitive adhesive layer 22 in the double-sided pressure-sensitive adhesive sheet 2 and the intermediate layer 23, or the double-sided pressure-sensitive adhesive sheet 2 On the outside of the first pressure-sensitive adhesive layer 21 and / or the second pressure-sensitive adhesive layer 22 (on the side of the release sheets 31 and 32), another layer may be present.

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

Hereinafter, the present invention will be described in more detail 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 a laminate having a first pressure-sensitive adhesive layer or a second pressure-sensitive adhesive layer (1-1) Preparation of (meth) acrylic acid ester polymer (A) 65 parts by mass of 2-ethylhexyl acrylate, N -The (meth) acrylic acid ester polymer (A) was prepared by copolymerizing 5 parts by mass of acryloylmorpholine, 15 parts by mass of isobornyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, the weight average molecular weight (Mw) was 500,000.

(1-2) Preparation of Adhesive Composition P 100 parts by mass (solid content conversion value; the same applies hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step (1-1) 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 linear curable compound (B) and a cross-linking agent. 0.15 parts by mass of a tolylizing isocyanate-based cross-linking agent (manufactured by Toyochem Co., Ltd., product name "BHS-8515") as (C), and benzophenone and 1-hydroxycyclohexylphenylketone as the photopolymerization initiator (D) are 1 part. Mixing with 0.5 parts by mass of a mixture of 1: 1 (manufactured by BASF, product name "Irgacure 500"), stirring well, and diluting with methyl ethyl ketone, the adhesive composition P can be obtained. A coating solution was obtained.

(1-3) Preparation of Laminated Material A heavy release type release sheet (1 side of a polyethylene terephthalate film is peeled off with a silicone-based release agent) from the coating solution of the adhesive composition P obtained in the above step (1-2). A coating layer was formed by applying a coating on the peeled surface of Lintec Corporation, product name "SP-PET752150") with a knife coater and then heat-treating at 90 ° C. for 1 minute. Next, on the coated layer, a peeling-treated surface of a light peeling type peeling sheet (manufactured by Lintec Corporation, product name "SP-PET382120") in which one side of the polyethylene terephthalate film was peeled with a silicone-based peeling agent was bonded. Then, by curing under the conditions of 23 ° C. and 50% RH for 7 days, the heavy release type release sheet / first pressure-sensitive adhesive layer (active energy ray curable, thickness: 100 μm) / light release type release sheet. A first laminated body having a structure was produced.

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

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring device (manufactured by TECLOCK Co., Ltd., product name "PG-02") in accordance with JIS K7130.

(2) Preparation of a laminate having an intermediate layer (2-1) Preparation of resin composition Q Polyvinyl acetate (VAc, weight average molecular weight (Mw): 20,000, Tg: 32 ° C.) 100 as the resin (E) 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 mass and 1 part by mass of a mixture of benzophenone and 1-hydroxycyclohexylphenylketone as a photopolymerization initiator (G) at a mass ratio of 1: 1 (manufactured by BASF, product name "Irgacure 500") are mixed. Then, the mixture was sufficiently stirred and diluted with methyl ethyl ketone to obtain a coating solution of the resin composition Q.

(2-2) Preparation of Laminated Body A heavy peeling type in the same manner as the above-mentioned adhesive composition P 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 laminated body having a structure of a release sheet / an intermediate layer (active energy ray curable, thickness: 10 μm) / a 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 under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
-GPC measuring device: HLC-8020 manufactured by Tosoh Corporation
-GPC column (passed in the following order): TSK guard volume HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C

(3) Preparation of double-sided adhesive sheet with release sheet The light release type release sheet is peeled off from the first laminate obtained in (1) above, and the third laminate obtained in (2) above is light. The release type release sheet was peeled off, and the exposed first pressure-sensitive adhesive layer and the intermediate layer were bonded so as to be in contact with each other, and the heavy release type release sheet was peeled off from the intermediate layer. Next, the light release type release sheet is peeled off from the second laminate obtained in (1) above, and the exposed second adhesive layer and the intermediate layer are bonded so as to be in contact with each other. A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained by sandwiching a double-sided pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive layer, an intermediate layer, and a second pressure-sensitive adhesive layer between two double-release type release sheets.

[Example 2]
The resin composition Q was prepared in the same manner as in Example 1 except that the blending amount of the active energy ray-curable compound (F) was changed to 5 parts by mass and the blending amount of the photopolymerization initiator (G) was changed to 0.5 parts by mass. A coating solution was prepared to prepare a third laminate. A double-sided pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 1 except that this third laminated body 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 (Mw): 20,000, Tg: 32 ° C.) was replaced with 100 parts by mass of polyvinyl acetate (VAc, weight average molecular weight (Mw)) as the resin (E). 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 pressure-sensitive adhesive sheet with a release sheet was produced in the same manner as in Example 1 except that this third laminated body was used.

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

[Comparative Example 1]
The light release type release sheet is peeled from the first laminate obtained in Example 1 (1), and the light release type release sheet is released from the second laminate obtained in Example 1 (1). The peeled and exposed first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are bonded so as to be in contact with each other, and two pressure-sensitive adhesive layers composed of a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer are formed. An adhesive sheet was obtained, which was sandwiched between the heavy release type release sheets. 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]
A polyethylene terephthalate film (thickness: 12 μm, Tg:) used as an intermediate layer on the exposed first pressure-sensitive adhesive layer by peeling the light release type release sheet from the first laminate obtained in (1) of Example 1. 80 ° C.) was pasted together. Next, the light release type release sheet was peeled off from the second laminate obtained in Example 1 (1), and the exposed second adhesive layer and the polyethylene terephthalate film were attached so as to be in contact with each other. Together, 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 is sandwiched between two double-release type release sheets. Obtained.

[Test Example 1] (Measurement of glass transition temperature)
The glass transition temperature (Tg) of the intermediate layer prepared and used in Examples and Comparative Examples is raised by a differential scanning calorimetry device (manufactured by TA Instrument Japan, product name "DSC Q2000"). -Measured at a temperature lowering 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 adhesive sheets prepared in Examples and Comparative Examples were laminated so as 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 is pulled at a speed of 200 mm / min after setting the distance between chucks to 20 mm with a universal tensile tester (manufactured by Orientec, product name "Tencilon RTA-T-2M"). A test was conducted 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 (Teikoku Printing Co., Ltd., product name "POS-911 Sumi") on the surface of a glass plate (manufactured by NSG Precision Co., Ltd., 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, the printed ultraviolet curable ink is cured by irradiating with ultraviolet rays (80 W / cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m / min), and a step (height of the step) due to printing is cured. A stepped glass plate having a value of 60 μm) was produced.

The release sheet on the second adhesive layer (thickness 50 μm) side was peeled off from the double-sided adhesive sheet with the release sheet obtained in Examples and Comparative Examples, and the exposed adhesive layer was separated from the polyethylene terephthalate (PET) having an easy adhesive layer. ) A film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) was bonded to an easy-adhesive layer. Next, 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 Fujipla, product name "LPD3214"), the laminate was laminated on the stepped glass plate so that the adhesive layer covered the entire surface of the frame-shaped print. Then, it was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa. At this stage, it was visually confirmed whether or not there were air bubbles in the double-sided adhesive sheet (particularly near the step due to the printing layer). 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 adhesive sheet was irradiated with ultraviolet rays through the PET film under the following ultraviolet irradiation conditions to cure the double-sided adhesive sheet.
<Ultraviolet irradiation conditions>
・ Uses UV conveyor device manufactured by Eye Graphics Co., Ltd. ・ Illuminance 200mW / cm ² , light intensity 1000mJ / cm ²
・ UV illuminance / photometer uses "UVPF-36" manufactured by iGraphics.

The laminate having the double-sided adhesive sheet cured as described above was stored for 72 hours under high temperature and high humidity conditions of 85 ° C. and 85% RH. After that, it was visually confirmed whether or not there were bubbles in the double-sided adhesive sheet (particularly near the step due to the printing layer). As a result, those with no bubbles were evaluated as ⊚, those with 10 or less bubbles were evaluated as ○, and those with more than 10 bubbles were 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 in the vicinity of the step (evaluation: Δ). The results are shown in Table 1.

[Test Example 4] (Evaluation of workability)
<A method>
The double-sided adhesive sheet with a release sheet obtained in Examples and Comparative Examples was cut by an automatic cutting machine (manufactured by Ogino Seisakusho Co., Ltd., product name "Super Cutter OSS-PN1 type NL"). This cutting was performed 10 times. The cut surface (length: 100 mm) of the 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 10 times 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: Out of 10 times, the adhesive squeezed out 10 times.

<B method>
The double-sided adhesive sheet with a release sheet obtained in Examples and Comparative Examples was cut into a length of 100 mm and a width of 100 mm. The cut double-sided adhesive sheet with a release sheet is placed on a horizontal table so that the release sheet on the second adhesive layer (thickness 50 μm) side faces upward, and the first adhesive layer (thickness 50 μm) is placed on a horizontal table. The release sheet on the side (thickness 100 μm) was fixed to the table with an adhesive.

Next, the blade of the cutter knife was inserted to the front of the release sheet of the lowermost layer (the position where the first adhesive layer was cut) so as to vertically cut at a position having a width of 50 mm. Then, only one side of the separated surface-side release sheet was removed. As a result, a double-sided pressure-sensitive adhesive sheet was obtained in which half of the surface was covered with a release sheet and the other half was exposed with a second pressure-sensitive adhesive layer.

Further, an adhesive tape (manufactured by Lintec Corporation, product name "PET50 (A) PL Thin 8LK") cut into a length of 100 mm and a width of 100 mm is applied to the double-sided adhesive sheet so that the adhesive surface is in contact with the double-sided adhesive sheet. It was pasted on the entire surface. In this bonding, sufficient pressure was applied from above the adhesive tape so that air bubbles did not remain 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 adhesive sheet in the portion where the release sheet remains on the surface remains on the release sheet in the lowermost layer, and the double-sided adhesive sheet in the portion where the second adhesive layer is exposed is the most together with the adhesive tape. It was removed from the underlying release sheet. This work was done 10 times. The cross section (length: 100 mm) of the double-sided adhesive 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 10 times 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: Out of 10 times, the adhesive squeezed out 10 times.

As can be seen from Table 1, the double-sided adhesive sheet obtained in the examples was excellent in step followability under initial 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 body constituent member.

1 ... Double-sided adhesive sheet with release sheet 2 ... Double-sided adhesive sheet 2'... Double-sided adhesive sheet after curing 21 ... First adhesive layer 22 ... Second adhesive layer 23 ... Intermediate layer 31, 32 ... Release sheet 4 ... Display Body 51 ... First display body component 52 ... Second display body component 6 ... Print layer

Claims (9)

A double-sided adhesive sheet for displays that uses a display module.
A first pressure-sensitive adhesive layer as an outer layer on one side,
A second pressure-sensitive adhesive layer as an outer layer on the other surface side,
It comprises an intermediate layer located between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.
The glass transition temperature of the intermediate layer is 0 ° C. or higher and 60 ° C. or lower.
The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are active energy ray-curable .
Young's modulus is 0.01 MPa or more and 100 MPa or less.
Double-sided adhesive sheet featuring that. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the intermediate layer is active energy ray-curable. The double-sided pressure-sensitive adhesive sheet according to claim 2, wherein the intermediate layer contains a resin having a glass transition temperature of 0 ° C. or higher and 60 ° C. or lower, and an active energy ray-curable component. Claims 1 to 3 , wherein 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 is 0.05 or more and 2 or less. The double-sided adhesive sheet according to any one of the items. Any one of claims 1 to 4 , characterized in that it is used for bonding one display body component having at least a step on the surface to be bonded and another display body component. Double-sided adhesive sheet described in. A double-sided adhesive sheet with a release sheet for displays using a display module.
Two release sheets and
Double-sided adhesive with a release sheet, comprising the double-sided adhesive sheet according to any one of claims 1 to 5 , which is sandwiched between the release sheets so as to be in contact with the release surface of the two release sheets. Sheet. It is a display that uses a display module.
At least one display body component having a step on the surface on the side to be bonded,
With other display body components,
A display obtained from the double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , wherein the one display body component and the other display body component are bonded to each other. It is a display that uses a display module.
At least one display body component having a step on the surface on the side to be bonded,
With other display body components,
A cured double-sided pressure-sensitive adhesive sheet obtained by curing the double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the one display body component and the other display body component are bonded to each other. A display characterized by being equipped. It is a method of manufacturing a display using a display module.
A laminate obtained by laminating one display body component member and another display body component member via the double-sided adhesive sheet according to any one of claims 1 to 5 is produced.
A method for manufacturing a display , which comprises irradiating the double-sided pressure-sensitive adhesive sheet of the laminated body with active energy rays to cure the double-sided pressure-sensitive adhesive sheet.

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