JP6743422B2 - Double-sided adhesive sheet - Google Patents

Description

The present invention relates to a double-sided PSA sheet. Specifically, the present invention relates to a double-sided pressure-sensitive adhesive sheet that includes at least one rubber-based pressure-sensitive adhesive layer and at least one acrylic-based pressure-sensitive adhesive layer, and has excellent reworkability, unevenness followability, and low water vapor transmission rate.

In recent years, electronic devices such as mobile phones, portable game machines, and digital cameras have rapidly become popular. Adhesive sheets are generally used to fix components that make up electronic devices and various devices. As a pressure-sensitive adhesive sheet used for fixing components, a pressure-sensitive adhesive sheet in which an acrylic pressure-sensitive adhesive layer is provided on one side or both sides of a base material is often used (Patent Document 1).

A flat panel display (FPD) such as a liquid crystal display (LCD) is widely used as a display device. In such a display device, various optical members such as an antireflection film for preventing reflection from an external light source and a protective film (protection film) for preventing scratches on the surface of the display device are usually used depending on the application. Is used. A pressure-sensitive adhesive sheet provided with an acrylic pressure-sensitive adhesive layer is also used for bonding optical members of these display devices (Patent Document 2).

In recent years, pressure-sensitive adhesive sheets are required to suppress mechanical deterioration of optical members, and development of pressure-sensitive adhesive sheets having low water vapor permeability is required. For example, Patent Document 3 discloses a double-sided pressure-sensitive adhesive sheet containing a rubber-based resin as a main component instead of an acrylic-based resin. The double-sided pressure-sensitive adhesive sheet of Patent Document 3 is composed of a pressure-sensitive adhesive composition in which a tackifier is mixed with a rubber-based resin, and such a double-sided pressure-sensitive adhesive sheet has excellent adhesive strength and transparency. It is said that the invasion of water can be suppressed. Moreover, in order to satisfy various properties required for the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet having a rubber-based pressure-sensitive adhesive layer and an acrylic pressure-sensitive adhesive layer has also been developed (Patent Document 4). In the example of Patent Document 4, the acrylic pressure-sensitive adhesive layer is formed of an acrylic block copolymer.

JP 2012-140605 A JP, 2003-238915, A International publication WO2014/069398 JP 2012-229358 A

Regarding the pressure-sensitive adhesive sheet used for the above-mentioned applications, while exhibiting excellent adhesiveness after the members are bonded to each other, it is desired to rework (re-peel) when re-bonding or the like becomes necessary. The demand is increasing. Especially when a liquid crystal display device is bonded to another member (for example, a touch panel module) or when a cover glass and a shatterproof film are bonded to each other when a defect such as dust entrapment occurs, the price is relatively high. The demand for reworking the liquid crystal display device and the cover glass in order to reuse them has increased significantly.
However, the pressure-sensitive adhesive sheets described in Patent Documents 1 and 2 have a problem that the reworkability is not sufficient and the pressure-sensitive adhesive remains on the adherend during the rework operation. The pressure-sensitive adhesive remaining on the adherend needs to be wiped off with a solvent or washed with a solvent, which causes a problem that it takes time and labor for reworking. Further, there is a problem that the water vapor permeability is high and the conductive layer is easily corroded in a high humidity environment.

On the other hand, the pressure-sensitive adhesive sheet described in Patent Document 3 is excellent in reworkability and has low water vapor permeability, but has poor irregularity followability, and when bonded to an adherend having irregularities, the pressure-sensitive adhesive sheet and irregularities are There was a problem that bubbles tend to remain in the.
Further, as in the pressure-sensitive adhesive sheet described in Patent Document 4, even if it has an acrylic pressure-sensitive adhesive layer and a rubber-based pressure-sensitive adhesive layer, the optical properties are not sufficient, and the optical article has a high haze value. It has been clarified by the study of the present inventors that the problem remains to be used as the above.

Therefore, in order to solve the problems of the prior art, the present inventors have provided a pressure-sensitive adhesive sheet having excellent optical properties, which has all of excellent unevenness followability and reworkability, and low water vapor permeability. We proceeded with the study for the purpose of providing a double-sided PSA sheet.

As a result of intensive studies to solve the above problems, the present inventors have found that in a double-sided pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer and a rubber-based pressure-sensitive adhesive layer, the acrylic pressure-sensitive adhesive layer is a specific copolymer. It was formed from the above, and the interlaminar strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer was set to a predetermined value or more, so that it had both excellent irregularity followability, reworkability, and low water vapor permeability. It was found that a double-sided PSA sheet can be obtained.
Specifically, the present invention has the following configurations.

[1] A double-sided PSA sheet including at least one rubber-based pressure-sensitive adhesive layer and at least one acrylic-based pressure-sensitive adhesive layer, wherein the acrylic-based pressure-sensitive adhesive layer contains an acrylic random copolymer, and the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer are combined. A double-sided pressure-sensitive adhesive sheet having an interlaminar strength of 10 N/25 mm or more between the pressure-sensitive adhesive layers.
[2] The double-sided pressure-sensitive adhesive sheet according to [1], wherein the rubber-based pressure-sensitive adhesive layer contains a styrene block copolymer.
[3] The double-sided pressure-sensitive adhesive sheet according to [1] or [2], wherein the rubber pressure-sensitive adhesive layer has a thickness of 15 μm or more.
[4] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the acrylic pressure-sensitive adhesive layer has a thickness of 15 μm or more.
[5] When the thickness (μm) of the rubber-based adhesive layer is P and the thickness (μm) of the acrylic-based adhesive layer is Q, P:Q=1:10 to 10:1 [1] to The double-sided pressure-sensitive adhesive sheet according to any one of [4].
[6] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [5], which has a haze of 1% or less.
[7] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [6], which has a total light transmittance of 85% or more.
[8] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [7], which has a water vapor permeability of 300 g/m ² ·day or less.
[9] The method for bonding an adherend, wherein the adherend has a height difference of 5% or more and 40% or less of the thickness of the double-sided pressure-sensitive adhesive sheet, according to any one of [1] to [8]. Double-sided adhesive sheet.
[10] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [9], which is for bonding optical members.
[11] A double-sided pressure-sensitive adhesive sheet with a release sheet, which has a release sheet on at least one surface of the double-sided pressure-sensitive adhesive sheet according to any one of [1] to [10].

According to the present invention, it is possible to obtain a double-sided pressure-sensitive adhesive sheet that has all of excellent irregularity followability, reworkability, and low water vapor permeability. The double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding optical members having stepped portions (uneven portions).

FIG. 1 is a cross-sectional view illustrating the structure of the double-sided pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a cross-sectional view illustrating the structure of the double-sided pressure-sensitive adhesive sheet of the present invention.

Hereinafter, the present invention will be described in detail. The description of the constituents described below may be made based on typical embodiments or specific examples, but the present invention is not limited to such embodiments.

(Double-sided adhesive sheet)
The present invention relates to a double-sided pressure-sensitive adhesive sheet including at least one rubber-based pressure-sensitive adhesive layer and at least one acrylic pressure-sensitive adhesive layer. In the double-sided pressure-sensitive adhesive sheet of the present invention, the acrylic pressure-sensitive adhesive layer contains an acrylic random copolymer. The interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer is 10 N/25 mm or more.
In the double-sided pressure-sensitive adhesive sheet of the present invention, by forming the acrylic pressure-sensitive adhesive layer from an acrylic random copolymer, the interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer can be increased. As a result, the double-sided pressure-sensitive adhesive sheet is prevented from delamination during rework work, and reworkability is improved. Further, since the double-sided pressure-sensitive adhesive sheet of the present invention has the above-mentioned constitution, it is characterized in that it easily expands in accordance with the peeling force and the double-sided pressure-sensitive adhesive sheet is not easily broken. This also contributes to the reworkability of the double-sided pressure-sensitive adhesive sheet of the present invention. Here, the excellent reworkability is that when peeling after sticking, a part of the adhesive of the double-sided PSA sheet does not remain on the adherend, and the double-sided PSA sheet does not break during reworking I mean. Furthermore, the double-sided pressure-sensitive adhesive sheet of the present invention can exhibit excellent unevenness followability and low water vapor permeability by having the above-mentioned constitution.

The double-sided pressure-sensitive adhesive sheet of the present invention is preferably a double-sided pressure-sensitive adhesive sheet having no support (base material). For this reason, the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer are laminated in a state of directly contacting each other. In the present invention, the interlaminar strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer may be 10 N/25 mm or more, preferably 12 N/25 mm or more, and 13 N/25 mm or more. More preferable. The upper limit of the interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer is preferably 125 N/25 mm. By setting the interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer within the above range, it is possible to suppress peeling between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer, The reworkability can be improved more effectively.

The interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer can be measured as follows. First, a 100 μm thick polyethylene terephthalate (PET) film (Toray Co., Ltd.) is placed on the acrylic pressure-sensitive adhesive layer side of the double-sided pressure-sensitive adhesive sheet via an acrylic double-sided adhesive sheet (Nitto Denko Corporation, trade name “No. 5000NS”). Product name "Cosmo Shine A4300") is pasted together. Then, the opposite side of the rubber-based pressure-sensitive adhesive layer was lined with a SUS plate through the same acrylic double-sided adhesive sheet (No. 5000NS) as described above, and then a strip-shaped test piece having a length of 100 mm and a width of 25 mm. Cut out to.
Next, from the one end of the test piece to the position of 30 mm in the longitudinal direction, with the acrylic adhesive layer of the adhesive sheet, or when the interlayer adhesiveness is good and peeling of the acrylic adhesive layer is difficult, the acrylic adhesive layer is removed. The PET film is peeled off together with the acrylic double-sided adhesive sheet (No. 5000NS) on the agent layer side (when the acrylic pressure-sensitive adhesive layer can be peeled off, the peeling interface is between the rubber-based pressure-sensitive adhesive layer/acrylic pressure-sensitive adhesive layer). Therefore, the peeling interface when the acrylic pressure-sensitive adhesive layer cannot be peeled is the layer between the acrylic pressure-sensitive adhesive layer/acrylic double-sided adhesive sheet (No. 5000NS)). The partially peeled test piece is gripped by a chuck of a tensile tester, peeled in a direction of 180 degrees at a pulling speed of 300 mm/min, and the peeling force required for the peeling is measured. If the measured peeling force is, for example, 10 N/25 mm or more, the interlayer strength between the rubber-based adhesive layer and the acrylic adhesive layer is 10 N/25 mm or more, and the rubber-based adhesive layer/acrylic The pressure-sensitive adhesive layer has a peeling force of 10 N/25 mm or more when peeling the pressure-sensitive adhesive layers from each other.

The elongation at break of the double-sided PSA sheet may be 500% or more, preferably 600% or more, more preferably 800% or more, further preferably 1000% or more, and 1500% or more. It is even more preferable that it is present, and it is particularly preferable that it is 2000% or more. The upper limit of the elongation at break of the double-sided PSA sheet is preferably 10,000%.
Further, stress at break of the double-sided pressure-sensitive adhesive sheet as long 0.4 N / mm ² or more, preferably 0.8N / mm ² or more, preferably 1.5 N / mm ² or more, 2. It is more preferably 0 N/mm ² or more. The upper limit of the stress at break of the double-sided PSA sheet is preferably 20 N/mm ² .

The elongation at break and the stress at break of the double-sided PSA sheet are measured using a tensile tester in accordance with JIS K6251. The measurement can be performed by rolling a sample (double-sided pressure-sensitive adhesive sheet) rolled into a rod shape having a diameter of 5 mm and a length of 70 mm under the conditions of an initial distance between chucks of 50 mm and a pulling speed of 1000 mm/min. The tensile test is performed in an environment of 23°C and relative humidity of 50%. The elongation at break represents the elongation just before breaking between the determined reference points of the test piece (double-sided PSA sheet) in the tensile test. The stress at break is a value obtained by dividing the tensile force at the break at the time of break in the tensile test by the initial cross-sectional area of the test piece. The tensile test is a measurement of elongation at break and stress at break in the length direction of the double-sided pressure-sensitive adhesive sheet.

In the present invention, when the elongation at break (%) of the double-sided pressure-sensitive adhesive sheet is A and the stress at break (N/mm ² ) is B, 100<A/B<1600 is preferable, and 200<A/B<1000 is more preferable, and 200<A/B<800 is further preferable. By setting the relationship between the elongation at break and the stress at break within the above range, the double-sided PSA sheet can be easily stretched corresponding to the peeling force applied, and the double-sided PSA sheet can be prevented from breaking. ..

The haze of the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 3% or less, more preferably 1% or less. In the present specification, the haze of the double-sided pressure-sensitive adhesive sheet refers to a value measured by a method according to JIS K7136. When measuring the haze, the double-sided pressure-sensitive adhesive sheet of the present invention is attached to a slide glass (product number: S9112) manufactured by Matsunami Glass Co., Ltd., and the haze value is measured. Specifically, after sticking the double-sided pressure-sensitive adhesive sheet to a slide glass manufactured by Matsunami Glass Co., Ltd., 0.5 MPa and 40° C. are applied to the laminated samples in order to eliminate the influence of fine air mixed in at the time of sticking. Autoclave (pressurized defoaming) treatment is performed for 30 minutes under the above conditions. After that, the release sheet on the opposite side of the glass bonding surface is peeled off, and the adhesive surface is exposed, and the measurement is performed using NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd.

The total light transmittance of the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The double-sided pressure-sensitive adhesive sheet of the present invention is characterized by high total light transmittance and excellent transparency. In the present specification, the total light transmittance of the double-sided pressure-sensitive adhesive sheet refers to a value measured by a method according to JIS K7136. The total light transmittance of the double-sided pressure-sensitive adhesive sheet can be measured by the same method as the method for measuring the haze value described above.

The water vapor transmission rate of the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 600 g/m ² ·day or less, more preferably 500 g/m ² ·day or less, and preferably 300 g/m ² ·day or less. It is more preferably 200 g/m ² ·day or less, still more preferably 100 g/m ² ·day or less. Since the double-sided pressure-sensitive adhesive sheet of the present invention has a low water vapor permeability, it is possible to effectively prevent intrusion of water. Therefore, mechanical deterioration of the optical member can be suppressed. In the present specification, the water vapor permeability of the double-sided pressure-sensitive adhesive sheet refers to a value measured according to the cup method defined in JIS Z 0208.

The double-sided pressure-sensitive adhesive sheet of the present invention is also excellent in unevenness followability (step followability). The excellent unevenness followability (step followability) means that when the double-sided pressure-sensitive adhesive sheet is attached to an adherend having a height difference of 5% to 40% of the thickness of the double-sided pressure-sensitive adhesive sheet, It means that air does not remain in the entire uneven portion. That is, the double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding an adherend having a height difference of 5% or more and 40% or less of the thickness of the double-sided pressure-sensitive adhesive sheet.

The total thickness of the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 50 μm or more, more preferably 100 μm or more, and further preferably 150 μm or more. The total thickness of the double-sided PSA sheet is preferably 500 μm or less, more preferably 400 μm or less, and further preferably 350 μm or less. By setting the total thickness of the double-sided pressure-sensitive adhesive sheet within the above range, excellent unevenness followability, reworkability, and low water vapor permeability can be easily achieved.

The thickness of one layer of the rubber-based pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 10 μm or more, more preferably 15 μm or more, further preferably 20 μm or more, and 25 μm or more. Is particularly preferable. The thickness of the rubber-based pressure-sensitive adhesive layer is preferably 490 μm or less, more preferably 400 μm or less, further preferably 300 μm or less, and particularly preferably 250 μm or less. By setting the thickness of the rubber-based pressure-sensitive adhesive layer within the above range, the reworkability can be improved and the water vapor permeability can be effectively reduced.

The thickness of one layer of the acrylic pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheet of the present invention is preferably 10 μm or more, more preferably 15 μm or more, further preferably 20 μm or more, and 25 μm or more. Is particularly preferable. The thickness of the acrylic pressure-sensitive adhesive layer is preferably 490 μm or less, more preferably 400 μm or less, further preferably 300 μm or less, and particularly preferably 250 μm or less. By setting the thickness of the acrylic pressure-sensitive adhesive layer within the above range, it is possible to enhance the unevenness followability.

In the present invention, when the thickness (μm) of the rubber-based pressure-sensitive adhesive layer is P and the thickness (μm) of the acrylic-based pressure-sensitive adhesive layer is Q, P:Q=1:10 to 10:1. preferable. By setting P:Q within the above range, the double-sided pressure-sensitive adhesive sheet of the present invention can easily exhibit excellent unevenness followability, reworkability, and low water vapor permeability.
The above-mentioned P represents the total thickness of the rubber-based pressure-sensitive adhesive layer when the double-sided pressure-sensitive adhesive sheet contains two or more rubber-based pressure-sensitive adhesive layers, and the above-described Q represents the acrylic pressure-sensitive adhesive on the double-sided pressure-sensitive adhesive sheet. When two or more layers are included, it represents the total thickness of the acrylic pressure-sensitive adhesive layer.

FIG. 1 is a cross-sectional view illustrating the structure of the double-sided pressure-sensitive adhesive sheet of the present invention. The double-sided pressure-sensitive adhesive sheet 1 of the present invention may include at least one rubber-based pressure-sensitive adhesive layer 10 and at least one acrylic-based pressure-sensitive adhesive layer 12, and as shown in FIG. 1, the rubber-based pressure-sensitive adhesive layer 10 and the acrylic pressure-sensitive adhesive layer 12 are included. It may have a structure in which each layer is laminated. Since the double-sided pressure-sensitive adhesive sheet 1 of the present invention has excellent unevenness followability, it can be applied to an adherend Z having an uneven structure (step structure) as shown in FIG. The layer in contact with the uneven structure (step structure) may be the rubber-based pressure-sensitive adhesive layer 10 (FIG. 1A) or the acrylic-based pressure-sensitive adhesive layer 12 (FIG. 1B). In the present invention, even if the layer in contact with the uneven structure (step structure) is the rubber-based pressure-sensitive adhesive layer 10, excellent uneven followability can be exhibited.
The height of the convex portion of the uneven structure on the surface of the adherend Z is preferably 5% or more and 40% or less of the total thickness of the double-sided pressure-sensitive adhesive sheet 1.

The double-sided pressure-sensitive adhesive sheet 1 of the present invention may include two or more layers including at least one layer selected from the rubber-based pressure-sensitive adhesive layer 10 and the acrylic pressure-sensitive adhesive layer 12. For example, as shown in FIG. 2A, it may include two acrylic pressure-sensitive adhesive layers 12 and the rubber pressure-sensitive adhesive layer 10 is disposed between the acrylic pressure-sensitive adhesive layers 12. .. Further, as shown in FIG. 2B, the rubber adhesive layer 10 may include two layers and the acrylic adhesive layer 12 may be disposed between the rubber adhesive layers 10. ..

The rubber-based pressure-sensitive adhesive layer 10 shown as a single-layer structure in FIGS. 1 and 2 may have a laminated structure of two or more rubber-based pressure-sensitive adhesive layers. May have a laminated structure of two or more acrylic pressure-sensitive adhesive layers.

<Rubber adhesive layer>
The double-sided pressure-sensitive adhesive sheet of the present invention includes at least one rubber-based pressure-sensitive adhesive layer. The rubber-based pressure-sensitive adhesive layer contains a rubber-based resin as a main component. Examples of rubber-based resins include natural rubber-based resins and synthetic rubber-based resins. Here, having the rubber-based resin as a main component means that the rubber-based resin is contained in an amount of 30% by mass or more, preferably 35% by mass or more, and more preferably 45%, based on the total mass of the rubber-based pressure-sensitive adhesive layer. It means that it contains more than mass %.

The rubber-based resin is preferably a synthetic rubber-based resin, and as the synthetic rubber-based resin, a styrene-based block copolymer and a hydrogenated product of the styrene-based block copolymer can be preferably exemplified. Examples of the styrene block copolymer include styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene styrene block copolymer (SBS). Further, styrene-butadiene rubber (SBR), polyisoprene rubber (IR), polyisobutylene (PIB), butyl rubber (IIR) and the like can also be used. You may use these synthetic rubbers individually or in combination of 2 or more types.

Among them, the rubber-based resin is preferably a styrene-based block copolymer, more preferably a hydrogenated product of a styrene-based block copolymer, and further preferably a styrene-hydrogenated isoprene-styrene copolymer. preferable.

The weight average molecular weight (Mw) of the rubber-based resin is preferably 10,000 or more and 1,000,000 or less, and more preferably 50,000 or more and 800,000 or less. The weight average molecular weight (Mw) is calculated based on a calibration curve prepared using a polystyrene standard substance by gel permeation chromatography (GPC) measurement.

The rubber pressure-sensitive adhesive layer preferably further contains a tackifier and a plasticizer.
Examples of the tackifier include petroleum-based resins such as styrene resins, terpene resins, rosin resins, C5 resins, C9 resins, and C5/C9 resins. Among them, styrene resin (styrene tackifier) is preferably used.
Examples of the plasticizer include paraffin oil, naphthene oil, and aromatic oil. Among them, paraffin oil is preferably used.

The content of the tackifier is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber-based adhesive layer. More preferable. Further, the content of the tackifier is preferably 90 parts by mass or less, and more preferably 80 parts by mass or less.
The content of the plasticizer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber-based pressure-sensitive adhesive layer. preferable. Further, the content of the plasticizer is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and further preferably 70 parts by mass or less.

The rubber pressure-sensitive adhesive layer preferably further contains a silane coupling agent. Examples of the silane coupling agent include a mercapto-based silane coupling agent containing a mercapto group, an epoxy-based silane coupling agent having an epoxy group, and a vinyl-based silane coupling agent having a vinyl group.
The content of the silane coupling agent is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and 0.1 parts by mass with respect to 100 parts by mass of the rubber-based pressure-sensitive adhesive layer. It is more preferable that the amount is at least parts by mass. Further, the content of the silane coupling agent is preferably 3 parts by mass or less, and more preferably 2 parts by mass or less.

The rubber pressure-sensitive adhesive layer preferably does not contain an antiblocking agent. By not containing the anti-blocking agent, the haze value becomes small and the pressure-sensitive adhesive sheet suitable for optical use can be obtained.

<Acrylic adhesive layer>
The double-sided pressure-sensitive adhesive sheet of the present invention includes at least one acrylic pressure-sensitive adhesive layer. The acrylic pressure-sensitive adhesive layer contains an acrylic resin as a main component. Examples of the acrylic resin include an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer.

The acrylic polymer contains a non-crosslinkable (meth)acrylic acid ester unit, and at least one selected from an acrylic monomer unit having a crosslinkable functional group and a bifunctional acrylic monomer unit. Here, the "monomer unit" is a repeating unit constituting a polymer. “Acrylic monomer” is a compound having a (meth)acryloyl group. The “(meth)acryloyl group” means an acryloyl group or a methacryloyl group. The non-crosslinkable acrylic monomer is an acrylic monomer having no crosslinkable group, and the crosslinkable acrylic monomer is a monomer having a crosslinkable group. The crosslinkable acrylic monomer may be an acrylic monomer or a non-acrylic monomer as long as it can be polymerized with the non-crosslinkable acrylic monomer, but it should be an acrylic monomer. Is preferred. Examples of the crosslinkable group include a carboxy group, a hydroxy group, an amino group, an epoxy group and a glycidyl group.

Examples of the non-crosslinkable acrylic monomer unit include (meth)acrylic acid ester units in which the hydrogen atom of the carboxy group of (meth)acrylic acid is replaced with a hydrocarbon group. In the present invention, the acrylic pressure-sensitive adhesive layer preferably contains a (meth)acrylic acid ester unit.

Specific examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, ( Isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate , Isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isobornyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, (meth) N-undecyl acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate Among them, it is preferable to use n-butyl acrylate, 2-ethylhexyl acrylate, and methyl acrylate from the viewpoint of adhesiveness. In the present invention, “(meth)acrylic acid” means to include both “acrylic acid” and “methacrylic acid”.

As the crosslinkable acrylic monomer unit, a carboxy group-containing copolymerizable monomer unit, a hydroxy group-containing copolymerizable monomer unit, an amino group-containing copolymerizable monomer unit, a glycidyl group-containing copolymerizable monomer unit. An example is a monomer unit. Examples of the carboxy group-containing copolymerizable monomer include, for example, α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and glataconic acid, and anhydrides thereof. Things can be mentioned.
Examples of the hydroxy group-containing copolymerizable monomer include (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Examples thereof include hydroxyalkyl, (meth)acrylic acid [(mono,di or poly)alkylene glycol] such as (meth)acrylic acid mono(diethylene glycol), and (meth)acrylic acid lactone such as (meth)acrylic acid monocaprolactone.
Examples of the amino group-containing copolymerizable monomer include (meth)acrylamide and allylamide.
Examples of the glycidyl group-containing copolymerizable monomer include glycidyl (meth)acrylate.

The acrylic polymer is preferably an acrylic random copolymer, more preferably a random copolymer of a crosslinkable acrylic monomer and a non-crosslinkable acrylic monomer. More specifically, it is preferably a random copolymer of at least one selected from n-butyl acrylate, 2-ethylhexyl acrylate and methyl acrylate, and acrylic acid, and an acrylic ester-based copolymer. Is preferred.

The weight average molecular weight (Mw) of the acrylic resin is preferably 200,000 or more and 2,500,000 or less, and more preferably 300,000 or more and 2,000,000 or less. The weight average molecular weight (Mw) is calculated based on a calibration curve prepared using a polystyrene standard substance by gel permeation chromatography (GPC) measurement.

The acrylic pressure-sensitive adhesive layer may further contain additives such as a softening agent, a crosslinking agent, and a pigment, if necessary. Further, in order to prevent deterioration of the acrylic pressure-sensitive adhesive layer with time, it is preferable to add an antioxidant. By adding an antiaging agent, it is possible to prevent a decrease in adhesive strength due to deterioration of the double-sided PSA sheet. Examples of the antiaging agent include general phenol-based antioxidants, phosphorus-based antioxidants, UV inhibitors and HALS (hindered amine-based stabilizers). The addition amount of the antioxidant is preferably 0.05 parts by mass or more and 5 parts by mass or less, and more preferably 0.1 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the acrylic resin. ..

(Production method for double-sided PSA sheet)
The process for producing the double-sided pressure-sensitive adhesive sheet of the present invention preferably includes a step of laminating a rubber-based pressure-sensitive adhesive layer and an acrylic pressure-sensitive adhesive layer. Each pressure-sensitive adhesive layer is preferably a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) formed by coating, and more preferably a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) formed by sequential coating. In addition, in this specification, sequential coating means that each pressure-sensitive adhesive layer is coated in each step and formed into a separate sheet.

Examples of the method for producing the double-sided pressure-sensitive adhesive sheet include the following production methods (1) and (2).

<Production method (1)>
The production method (1) includes a step of applying an acrylic pressure-sensitive adhesive layer-forming coating liquid on a release sheet to form an acrylic pressure-sensitive adhesive layer to obtain an acrylic pressure-sensitive adhesive sheet, and another release sheet. And a step of applying a coating liquid for forming a rubber-based pressure-sensitive adhesive layer to form a rubber-based pressure-sensitive adhesive layer to obtain a rubber-based pressure-sensitive adhesive sheet. Then, the method includes a step of stacking the acrylic pressure-sensitive adhesive sheet and the rubber pressure-sensitive adhesive sheet so that the acrylic pressure-sensitive adhesive layer and the rubber pressure-sensitive adhesive layer are in contact with each other and pressure bonding. The production method (1) further comprises stacking a third pressure-sensitive adhesive layer formed on another release sheet such that the third pressure-sensitive adhesive layer is in contact with the laminate of the acrylic pressure-sensitive adhesive layer and the rubber pressure-sensitive adhesive layer. The step of crimping may be included.

<Production method (2)>
The production method (2) includes a step of simultaneously coating the release sheet with the acrylic pressure-sensitive adhesive layer forming coating liquid and the rubber pressure-sensitive adhesive layer forming coating liquid in multiple layers. The production method (2) further comprises stacking a third pressure-sensitive adhesive layer formed on another release sheet such that the third pressure-sensitive adhesive layer is in contact with the laminate of the acrylic pressure-sensitive adhesive layer and the rubber pressure-sensitive adhesive layer. The step of crimping may be included.

(Double-sided adhesive sheet with release sheet)
A release sheet is preferably laminated on at least one surface of the double-sided PSA sheet, and the double-sided PSA sheet of the present invention is preferably a double-sided PSA sheet with a release sheet. The release sheet is preferably laminated on at least one surface of the adhesive sheet, and more preferably laminated on both surfaces. As the release sheet, a polymer film provided with a release agent layer can be used. When the release sheet is laminated on both sides of the pressure-sensitive adhesive sheet, it is preferable that the two release sheets (the first release sheet and the second release sheet) have different release forces. Specifically, different release agents are used. Preferably. By laminating release sheets having different release forces in this way, when releasing the release sheet on the light release force side, it is possible to suppress the tearing phenomenon in which the adhesive sheet floats from the release sheet on the heavy release force side. .. The release force of the release sheet on the heavy release force side is preferably 0.08 N/50 mm or more and 2.00 N/50 mm or less, and the release force of the release sheet on the light release force side is 0.01 N/50 mm or more 0.20 N/ It is preferably 50 mm or less. The ratio (R _H /R _L ) of the peeling force R _H on the heavy peeling force side to the peeling force R _L of the sheet on the light peeling force side is preferably 1.5 or more.

Further, in a mode in which the release sheets are laminated on both sides of the pressure-sensitive adhesive sheet, when the difference in the release force between the two release sheets can be maintained, the first release sheet is first coated with the pressure-sensitive adhesive coating solution and then the first release sheet is applied. A release sheet may be attached and pressure bonded. The pressure-sensitive adhesive sheet may have a sheet shape or may be rolled up into a roll shape.

(Double-sided adhesive sheet for optical members)
The double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding various members. The application of bonding is not limited, but the double-sided pressure-sensitive adhesive sheet of the present invention is preferably a double-sided pressure-sensitive adhesive sheet for bonding optical members. Examples of the optical member may include a liquid crystal cell or a touch panel. In addition, since the double-sided pressure-sensitive adhesive sheet of the present invention has a feature of having a very low water vapor permeability, it is bonded to a sensor surface using a conductive member such as ITO in a touch panel or an organic EL constituent member is bonded. Can be used together. In particular, the double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for bonding the sealed organic EL element and another member.

(Laminate)
The present invention may relate to a laminate having the double-sided pressure-sensitive adhesive sheet and the adherend described above. Specifically, it is a laminate having a double-sided pressure-sensitive adhesive sheet and an adherend, and the adherend to the adherend is a rubber-based adhesive layer, or the adherend to the adherend is acrylic. The present invention relates to a laminate which is a pressure-sensitive adhesive layer. In the present invention, excellent reworkability can be exhibited in any laminate. Further, in the laminated body, when the adherend has an uneven portion, air does not remain between the uneven portion and the double-sided pressure-sensitive adhesive sheet.

(Image display device)
The present invention may be related to an image display device provided with a double-sided pressure-sensitive adhesive sheet for optical members. An image display device can be produced by bonding the double-sided pressure-sensitive adhesive sheet of the present invention to an optical member and incorporating the optical member with the double-sided pressure-sensitive adhesive sheet into the image display device.

The features of the present invention will be described more specifically below with reference to Examples and Comparative Examples. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following specific examples. In addition, below, Examples 1-3, 6 and 7 shall be read as reference examples 1-3, 6 and 7, respectively.

(Example 1)
[Production of adhesive for rubber-based adhesive layer]
The pressure-sensitive adhesive for the rubber-based pressure-sensitive adhesive layer is 100 parts by mass of a pelletized styrene-based block copolymer (manufactured by Kuraray Co., product number: Septon 2063 (styrene-hydrogenated isoprene-styrene copolymer)), a silane coupling agent ( Shin-Etsu Chemical Co., Ltd. product number: X-41-1818) 0.6 parts by mass, styrene-based tackifier (Mitsui Chemicals Co., product number: FTR8100SX100) 70 parts by mass, Idemitsu paraffin oil (made by Idemitsu Co., Ltd. Part number: Diana Process Oil PW-90) 50 parts by mass was dissolved in toluene and stirred until uniform. The stirring was performed at 23° C. for 4 hours. The solid content concentration of the obtained pressure-sensitive adhesive for rubber-based pressure-sensitive adhesive layer was 45% by mass. The solid content means a rubber component, a silane coupling agent, a tackifier, and an oil component.

[Creation of double-sided adhesive sheet]
The pressure-sensitive adhesive for the rubber-based pressure-sensitive adhesive layer prepared above was applied to a light release side release sheet (RL-07(L) manufactured by Oji F-Tex Co., Ltd.) with a knife coater so as to have a thickness of 250 μm after drying. Then, it was dried at 100° C. for 10 minutes to dry the solvent toluene to obtain a rubber-based pressure-sensitive adhesive layer (rubber-based pressure-sensitive adhesive sheet) having a release sheet on one surface.
Next, an acrylic pressure-sensitive adhesive layer was laminated on the obtained rubber pressure-sensitive adhesive layer. In the step of laminating the acrylic pressure-sensitive adhesive layer, the pressure-sensitive adhesive surface of the acrylic pressure-sensitive adhesive layer (acrylic pressure-sensitive adhesive sheet) (manufactured by Shin-Tak Kasei Co., SA03:OCA/acrylic) from which the release sheet on the light release side is peeled is laminated. Thus, a double-sided pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with release sheet) was obtained. The thickness of the acrylic pressure-sensitive adhesive layer was 50 μm.

(Example 2)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that the thickness of the rubber-based pressure-sensitive adhesive layer was 100 μm and the thickness of the acrylic pressure-sensitive adhesive layer was 100 μm.

(Example 3)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that the thickness of the rubber-based pressure-sensitive adhesive layer was 25 μm and the thickness of the acrylic-based pressure-sensitive adhesive layer was 200 μm.

(Example 4)
The pressure-sensitive adhesive for a rubber-based pressure-sensitive adhesive layer obtained in Example 1 was applied to a release sheet on the heavy release side (RL-07 (6.5) manufactured by Oji F-Tex Co., Ltd.) so as to have a thickness of 25 μm after drying. (surface). Then, a 100 μm acrylic pressure-sensitive adhesive layer (SA03) obtained by peeling off the release sheet (RL-07 (L) manufactured by Oji Ftex Co., Ltd.) on the light release side was laminated (intermediate layer). Peel off the release sheet of the acrylic pressure-sensitive adhesive layer on the side opposite to the side where the rubber-based pressure-sensitive adhesive layer is laminated, and stick the same 25 μm adhesive surface of the rubber-based pressure-sensitive adhesive layer as the surface layer applied to the light-release side release sheet. Yes (back layer). Thus, a double-sided pressure-sensitive adhesive sheet with a release sheet having a pressure-sensitive adhesive layer having a three-layer structure was obtained.

(Example 5)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 4 except that the surface layer and the back layer in Example 4 were each 25 μm acrylic pressure-sensitive adhesive layers, and the intermediate layer was 100 μm rubber-type pressure-sensitive adhesive layers.

(Example 6)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that the thickness of the rubber-based pressure-sensitive adhesive layer was 10 μm and the thickness of the acrylic pressure-sensitive adhesive layer was 200 μm.

(Example 7)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that the thickness of the rubber-based pressure-sensitive adhesive layer was 250 μm and the thickness of the acrylic-based pressure-sensitive adhesive layer was 10 μm.

(Comparative Example 1)
A 100 μm thick rubber-based pressure-sensitive adhesive layer was applied to the heavy release side release sheet in the same manner as in Example 1, and then the light release side sheet was laminated to obtain a double-sided adhesive sheet with a release sheet.

(Comparative example 2)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Comparative Example 1 except that an acrylic pressure-sensitive adhesive layer (manufactured by Shin-Tak Kasei Co., NA084:OCA/acrylic) was used as the double-sided pressure-sensitive adhesive sheet.

(Comparative example 3)
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Comparative Example 1 except that the double-sided pressure-sensitive adhesive sheet was an acrylic pressure-sensitive adhesive layer (SA114; OCA/acrylic type, manufactured by Shin-Tak Kasei Co., Ltd.).

(Evaluation)
(Method of measuring elongation at break and stress at break)
Elongation at break and stress at break were measured by mounting a double-sided pressure-sensitive adhesive sheet having a diameter of 5 mm and a length of 70 mm on a tensile tester and pulling at a chucking distance of 50 mm at a pulling speed of 1000 mm/min.

(Evaluation of reworkability)
The double-sided pressure-sensitive adhesive sheets of Examples and Comparative Examples were cut into pieces each having a size of 5 cm×5 cm, the release film on the light release side was peeled off, and the sheets were attached to soda glass. Then, the autoclave was used for treatment at 0.5 MPa and 40° C. for 30 minutes to remove the release film on the heavy release side. Then, the double-sided pressure-sensitive adhesive sheet was reworked by peeling by hand (peeling from the glass). The reworkability of the double-sided PSA sheet at that time was evaluated according to the following criteria.
◯: The double-sided pressure-sensitive adhesive sheet was easily and neatly peeled off from the glass, leaving no adhesive substance.
Δ: The double-sided pressure-sensitive adhesive sheet is peeled off from the glass, but the double-sided pressure-sensitive adhesive sheet is cut off on the way and is difficult to peel off.
X: The double-sided pressure-sensitive adhesive sheet is immediately cut and the double-sided pressure-sensitive adhesive sheet is not peeled off from the glass.

(Interlayer strength)
The interlaminar strength can be measured as follows. First, a 100 μm thick polyethylene terephthalate (PET) film (Toray Co., Ltd.) is placed on the acrylic pressure-sensitive adhesive layer side of the double-sided pressure-sensitive adhesive sheet via an acrylic double-sided adhesive sheet (Nitto Denko Corporation, trade name “No. 5000NS”). Product name "Cosmo Shine A4300") was pasted together. Then, the opposite side of the rubber-based pressure-sensitive adhesive layer was lined with a SUS plate through the same acrylic double-sided adhesive sheet (No. 5000NS) as described above, and then a strip-shaped test piece having a length of 100 mm and a width of 25 mm. I cut it out.
Next, from the one end of the test piece to the position of 30 mm in the longitudinal direction, with the acrylic adhesive layer of the adhesive sheet, or when the interlayer adhesiveness is good and peeling of the acrylic adhesive layer is difficult, the acrylic adhesive layer is removed. The PET film was peeled off together with the acrylic double-sided adhesive sheet (No. 5000NS) on the side of the agent layer (The peeling interface when the acrylic pressure-sensitive adhesive layer could be peeled off was a rubber-based pressure-sensitive adhesive layer/acrylic pressure-sensitive adhesive layer). When the acrylic pressure-sensitive adhesive layer cannot be peeled off between layers, the peeling interface is the layer between the acrylic pressure-sensitive adhesive layer/acrylic double-sided adhesive sheet (No. 5000NS)). The partially peeled test piece was gripped by a chuck of a tensile tester, peeled in a direction of 180 degrees at a pulling speed of 300 mm/min, and the peeling force required for the peeling was measured. When the peeling interface is between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer, the measured peeling force becomes the interlayer strength. When the peeling interface is between the acrylic pressure-sensitive adhesive layer and the acrylic double-sided pressure-sensitive adhesive sheet, it can be seen that the interlayer strength between the acrylic pressure-sensitive adhesive layer and the rubber pressure-sensitive adhesive layer is higher than the measured value. The interlayer strength between the agent layer and the rubber-based pressure-sensitive adhesive layer is “>measured value N/25 mm”.

(Evaluation of water vapor permeability)
The double-sided pressure-sensitive adhesive sheets of Examples and Comparative Examples were cut out so as to have a diameter 10 mm larger than the inner diameter of the cup to be used, the light-release side and heavy-release side release sheets were peeled off, and only the pressure-sensitive adhesive layer was attached to the cup. Then, the water vapor permeability was measured according to the cup method of JIS Z 0208.

(Evaluation of unevenness followability)
Printing was performed on the non-tin surface of the soda glass so as to be formed within the range of 5 to 10% with respect to the thickness of the double-sided pressure-sensitive adhesive sheet to obtain a printed step glass.
<Heavy peeling side unevenness conformability>
100 μm PET (manufactured by Toyobo Co., Ltd., product number: Cosmoshine A4300) was attached to the adhesive layer exposed by peeling off the release sheet on the light release side. Then, the uneven surface of the printing step glass was attached to the exposed pressure-sensitive adhesive layer of the release sheet on the heavy release side to obtain a transparent laminate. A pressure was applied to the transparent laminate for 10 minutes under the conditions of a temperature of 40° C. and a pressure of 0.5 MPa in a pressure defoaming device.
<Light release side unevenness conformability>
The concavo-convex surface of the printing step glass was attached to the pressure-sensitive adhesive layer exposed by peeling off the release sheet on the light release side. Subsequently, 100 μm PET (manufactured by Toyobo Co., Ltd., product number: Cosmoshine A4300) was attached to the adhesive layer exposed by peeling off the release sheet on the heavy release side to obtain a transparent laminate. A pressure was applied to the transparent laminate for 10 minutes under the conditions of a temperature of 40° C. and a pressure of 0.5 MPa in a pressure defoaming device.
(Evaluation criteria)
The degree of adhesion of the printing step glass was observed using a microscope (magnification: 25 times) and evaluated according to the following criteria.
◯: The uneven portion is completely filled with the adhesive.
Δ: A small amount of air remains in the uneven portion.
X: Air remains in the entire uneven portion.

(Haze and total light transmittance)
The haze of the double-sided PSA sheet was measured by the method based on JIS K7136. When measuring the haze, the double-sided pressure-sensitive adhesive sheet was attached to a slide glass (product number: S9112) manufactured by Matsunami Glass Co., Ltd., and the haze value was measured. Specifically, after sticking the double-sided pressure-sensitive adhesive sheet to a slide glass manufactured by Matsunami Glass Co., Ltd., 0.5 MPa and 40° C. are applied to the laminated samples in order to eliminate the influence of fine air mixed in at the time of sticking. Autoclave (pressure defoaming) treatment for 30 minutes under the conditions described above, then peel off the release sheet on the opposite side of the glass-bonding surface, and with the adhesive side exposed, NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd. It was measured using.
The total light transmittance of the double-sided pressure-sensitive adhesive sheet was also measured by the same method as the method for measuring the haze value described above.

It can be seen that the double-sided pressure-sensitive adhesive sheets of Examples are excellent in reworkability and unevenness followability. Further, the double-sided pressure-sensitive adhesive sheets of the examples have achieved low water vapor permeability.
On the other hand, it can be seen that the double-sided pressure-sensitive adhesive sheet having only the rubber-based pressure-sensitive adhesive layer of Comparative Example 1 is inferior in the unevenness followability as compared with the Examples. It can be seen that the double-sided pressure-sensitive adhesive sheets of the acrylic pressure-sensitive adhesive layer alone shown in Comparative Examples 2 and 3 are inferior in reworkability and high in water vapor transmission rate as compared with Examples.

1 Double-sided pressure-sensitive adhesive sheet 10 Rubber-based pressure-sensitive adhesive layer 12 Acrylic pressure-sensitive adhesive layer Z Adherend

Claims (10)

A rubber pressure-sensitive adhesive layer and an acrylic pressure-sensitive adhesive layer, and the rubber pressure-sensitive adhesive layer, the acrylic pressure-sensitive adhesive layer and the rubber pressure-sensitive adhesive layer in this order, or the acrylic pressure-sensitive adhesive layer. A double-sided pressure-sensitive adhesive sheet containing the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer in this order,
The acrylic pressure-sensitive adhesive layer contains an acrylic random copolymer,
The interlayer strength between the rubber-based pressure-sensitive adhesive layer and the acrylic pressure-sensitive adhesive layer is 10 N/25 mm or more,
The rubber-based pressure-sensitive adhesive layer is a double-sided pressure-sensitive adhesive sheet containing a styrene-based block copolymer, a silane coupling agent, a stin-based tackifier, and paraffin-based oil. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the thickness of the rubber-based pressure-sensitive adhesive layer is 15 μm or more. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the acrylic pressure-sensitive adhesive layer has a thickness of 15 μm or more. When the thickness (μm) of the rubber-based pressure-sensitive adhesive layer is P and the thickness (μm) of the acrylic-based pressure-sensitive adhesive layer is Q, P:Q=1:10 to 10:1. The double-sided pressure-sensitive adhesive sheet according to any one of 1. The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 4, which has a haze of 1% or less. The double-sided pressure-sensitive adhesive sheet according to claim 1, which has a total light transmittance of 85% or more. The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 6, which has a water vapor transmission rate of 300 g/m ² ·day or less. For attaching adherends,
The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the adherend has a height difference of 5% or more and 40% or less of a thickness of the double-sided pressure-sensitive adhesive sheet. The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which is for bonding an optical member. A double-sided pressure-sensitive adhesive sheet with a release sheet, comprising a release sheet on at least one surface of the double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 9.

Images