JP7020907B2 - Double-sided adhesive tape - Google Patents

Description

The present invention relates to a double-sided adhesive tape that has high adhesive strength and can be peeled off without damaging the adherend.

Double-sided adhesive tape is used for assembly in portable electronic devices (for example, mobile phones, personal digital assistants, etc.) equipped with an image display device or an input device. Specifically, for example, a cover panel for protecting the surface of a portable electronic device is adhered to a touch panel module or a display panel module, a touch panel module and a display panel module are adhered to each other, or a sensor or a battery pack is fixed. Double-sided adhesive tapes are used for this purpose (for example, Patent Documents 1 and 2). Double-sided adhesive tape is also used for fixing vehicle parts (for example, an in-vehicle panel) to a vehicle body.

Japanese Unexamined Patent Publication No. 2009-242541 Japanese Unexamined Patent Publication No. 2009-258274

Conventionally, discarded electronic devices are recycled by taking out reusable parts such as sensors and battery packs before final disposal. However, when the parts to be collected are fixed by the double-sided adhesive tape, there is a problem that the parts may be damaged when they are peeled off from the double-sided adhesive tape and tried to be collected.

For example, when collecting a component fixed to a substrate with a double-sided adhesive tape, the end of the component is usually lifted and peeled off from the double-sided adhesive tape as shown in the left figure of FIG. 1 (a). However, if such a peeling method is performed on a part that has been miniaturized or thinned in recent years, the part may be damaged because it cannot withstand the force at the time of peeling as shown in the right figure of FIG. 1 (a). There was a problem. In order to solve this problem, it was considered to pull the double-sided adhesive tape in the horizontal direction to peel it off as shown in FIG. 1 (b), but the conventional double-sided adhesive tape has double-sided adhesive as shown in FIG. 1 (c). There was a problem that the tape could not withstand the force in the horizontal direction and was torn, leaving it on the parts or removing only a part of the double-sided adhesive tape. In particular, the double-sided adhesive tape used for fixing the parts has high adhesive strength because it is necessary to securely fix the parts, and the double-sided adhesive tape is more easily torn.

In view of the above situation, it is an object of the present invention to provide a double-sided adhesive tape that has high adhesive strength and can be peeled off without damaging the adherend.

The present invention is a double-sided adhesive tape having adhesive layers on both sides of a base material layer, wherein the double-sided adhesive tape has a tensile breaking strength of 10 MPa or more and the double-sided adhesive tape has a tensile breaking elongation of 1000% or more. The tensile breaking strength of the double-sided adhesive tape is higher than the 0 ° peeling strength of peeling the double-sided adhesive tape sandwiched between two stainless steel plates in the direction horizontal to the adhesive surface without bending, and the 0 ° peeling strength. Is a double-sided adhesive tape having a peeling strength of less than 180 ° with respect to the stainless steel plate.
The present invention will be described in detail below.

The double-sided adhesive tape of the present invention has an adhesive layer on both sides of the base material layer.
The two pressure-sensitive adhesive layers existing on both sides of the base material layer may be made of the same pressure-sensitive adhesive or may be made of different pressure-sensitive adhesives.

The double-sided adhesive tape of the present invention has a tensile breaking strength of 10 MPa or more.
Since the tensile breaking strength of the double-sided adhesive tape is 10 MPa or more, it is possible to prevent the double-sided adhesive tape from being torn even when the double-sided adhesive tape is pulled in a direction horizontal to the adhesive surface and peeled off. From the viewpoint of further suppressing the tearing of the double-sided tape, the preferable lower limit of the tensile breaking strength is 12 MPa, and the more preferable lower limit is 15 MPa. The upper limit of the tensile breaking strength is not particularly limited, but is preferably 50 MPa. The tensile breaking strength can be adjusted depending on the type of the base material. The tensile breaking strength is measured by performing a tensile test using a tensile tester in accordance with JIS K7161 under the conditions of a measurement temperature of 23 ° C. and a humidity of 50%, a sample chuck distance of 5 mm, and a speed of 300 mm / min. can do.

The double-sided adhesive tape of the present invention has a tensile elongation at break of 1000% or more.
Since the tensile elongation at break of the double-sided adhesive tape is 1000% or more, it is possible to prevent the double-sided adhesive tape from being torn even when the double-sided adhesive tape is pulled in a direction horizontal to the adhesive surface and peeled off. From the viewpoint of further suppressing the tearing of the double-sided tape, the preferable lower limit of the tensile elongation at break is 1200%, and the more preferable lower limit is 1400%. The upper limit of the tensile elongation at break is not particularly limited, but is preferably 4000%. The tensile elongation at break can be adjusted depending on the type of the base material. The tensile elongation at break is based on JIS K7161-2, and a tensile test is performed using a tensile tester under the conditions of a measurement temperature of 23 ° C. and a humidity of 50%, a sample chuck distance of 5 mm, and a speed of 300 mm / min. It can be measured by this.

The double-sided adhesive tape of the present invention has a tensile breaking strength higher than the 0 ° peel strength of peeling the double-sided adhesive tape sandwiched between two stainless steel plates in a direction horizontal to the adhesive surface without bending.
Since the tensile breaking strength of the double-sided adhesive tape is higher than the 0 ° peel strength, it is possible to prevent the double-sided adhesive tape from being torn even when the double-sided adhesive tape is pulled in a direction horizontal to the adhesive surface and peeled off. The 0 ° peel strength can be measured by the following method.
First, the double-sided adhesive tape is cut into 25 mm × 30 mm. Next, as shown in FIG. 2, the portion of the double-sided adhesive tape 4 cut from one short side to the other short side up to 10 mm is formed by two stainless steel plates 5 (SUS304, SUS304, compliant with JIS G4305 and JIS B0601. Temporarily press with a finger to the surface finish BA, surface roughness 50 nm, size 50 mm x 125 mm). After temporary crimping, a 2 kg rubber roller is reciprocated twice on the test piece at a speed of 300 mm / min to prepare a test sample for 0 ° peel strength evaluation. Further, the side opposite to the side on which the double-sided adhesive tape of both stainless steel plates 5 is sandwiched is sandwiched by the chuck 6. Then, the double-sided adhesive tape 4 is pulled in a direction horizontal to the adhesive surface at a peeling speed of 300 mm / min at a temperature of 23 ° C. and a humidity of 50% without bending, and the force required for peeling is measured.

In the double-sided adhesive tape of the present invention, the 0 ° peel strength is lower than the 180 ° peel strength with respect to the stainless steel plate.
Since the 0 ° peel strength is lower than the 180 ° peel strength with respect to the stainless steel plate used for measuring the 0 ° peel strength, the adherend can be reliably fixed until the double-sided adhesive tape is peeled, and the double-sided adhesive can be adhered. Even when the tape is pulled in a direction horizontal to the adhesive surface and peeled off, it is possible to prevent the double-sided tape from being torn. As shown in FIG. 3, the 180 ° peel strength measures the force required to attach the double-sided adhesive tape 4 to the stainless steel plate 5, bend the end of the double-sided adhesive tape 4 by 180 °, pull it, and peel it off. It can be decided by. More specifically, it can be measured by the following method.
A test piece is prepared by cutting the double-sided adhesive tape into strips having a width of 24 mm. Next, the test piece is placed on a stainless steel plate (SUS304, surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) conforming to JIS G4305 and JIS B0601 so that the adhesive layer faces the stainless steel plate. .. Then, the test piece and the stainless steel plate are bonded to each other by reciprocating a 2 kg rubber roller once on the test piece at a speed of 300 mm / min. Further, according to JIS Z0237, a polyethylene terephthalate film having a thickness of 25 μm specified in JIS C2318 is superposed on the test piece, and another 2 kg rubber roller is reciprocated on the film at a speed of 300 mm / min to peel off 180 °. Use as a test sample for strength evaluation. Then, it is allowed to stand at a temperature of 23 ° C. and a humidity of 50% for 24 hours, and a tensile test in the 180 ° direction is performed at a peeling speed of 300 mm / min according to JIS Z0237, and a 180 ° peeling strength (N / 25 mm) is measured.

The raw material of the base material layer is not particularly limited as long as it satisfies the tensile breaking strength and the tensile breaking elongation. Examples of the base material raw material satisfying the tensile breaking strength and the tensile breaking elongation include polyethylene, α-olefin copolymer, polyurethane, styrene-based elastomer and the like. Among them, at least one selected from the group consisting of polyethylene, α-olefin copolymer and polyurethane as the raw material of the base material layer because it is a double-sided adhesive tape having more excellent tensile breaking strength and tensile breaking elongation. It is preferable to include the above, and it is more preferable that it is an α-olefin copolymer. The raw material of the base material layer may be only one kind or two or more kinds.

The thickness of the base material of the base material layer is not particularly limited, but a preferable lower limit is 10 μm, and a more preferable lower limit is 20 μm. When the thickness of the base material is at least the above lower limit, the strength of the obtained double-sided adhesive tape is sufficiently improved, and the tape is less likely to be torn at the time of peeling. The upper limit of the thickness of the base material layer is not particularly limited, but is preferably 1 mm or less. When the thickness of the base material is not more than the upper limit, the weight of the electronic component including the double-sided adhesive tape can be reduced, and the double-sided adhesive tape having excellent flexibility and handleability can be obtained.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited as long as it satisfies the above-mentioned 0 ° peel strength and the above-mentioned 180 ° peel strength. Examples of the pressure-sensitive adhesive satisfying the above-mentioned 0 ° peel strength and the above-mentioned 180 ° peel strength include styrene-based elastomers, urethane-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, and silicon-based pressure-sensitive adhesives. Among them, it is preferable to contain a styrene-based elastomer because the double-sided adhesive tape can be peeled off without adhesive residue following the stretching of the base material at the time of peeling.

The styrene-based elastomer is not particularly limited, and for example, styrene ethylene propylene styrene block copolymer (SEPS), hydrogenated styrene butadiene rubber (HSBR), styrene ethylene butylene styrene block copolymer (SEBS), styrene ethylene propylene block. Polymer (SEP), Styrene Ethylene Butylene Block Polymer (SEB), Styrene-Isoprene Block Polymer (SI), Styrene-Isoprene-Styrene Block Polymer (SIS), Styrene-butadiene Block Polymer (SI) SB), styrene-butadiene-styrene block copolymer (SBS) and the like can be mentioned. Of these, SEPS and SEBS are particularly suitable because the shape of the styrene segment, which will be described later, tends to be spherical.

The styrene-based elastomer preferably has a spherical styrene segment having a diameter of 5 nm or more due to intramolecular phase separation.
The styrene-based elastomer consists of a rubber segment that exhibits rubber elasticity and a styrene segment that serves as a pseudo-bridge point of the rubber segment. Since the rubber segment and the styrene segment have low compatibility, the rubber segment and the styrene segment are present in the molecule. It has a non-uniform phase-separated structure that exists separately. When the styrene segment is spherical and has a diameter of 5 nm or more, the rubber segment interacts with the base material for a base material having a low SP value, and for a base material having a high SP value. Since the styrene segment interacts with the base material, the adhesive force between the pressure-sensitive adhesive layer and the base material layer can be improved. As a result, it becomes difficult for the pressure-sensitive adhesive layer to peel off from the base material layer, and it becomes difficult for adhesive to remain on the adherend. From the viewpoint of suppressing the peeling of the pressure-sensitive adhesive layer from the substrate and further suppressing the adhesive residue on the adherend, the more preferable lower limit of the diameter is 6 nm. The upper limit of the diameter is not particularly limited, but is limited to about 100 nm from the viewpoint of the stability of the spherical structure.

The styrene-based elastomer preferably has a hydrogenation rate of 95% or more, more preferably 96% or more, from the viewpoint of further suppressing contamination of the adherend. By setting the hydrogenation rate of the styrene-based elastomer to be equal to or higher than the above lower limit, contamination of the adherend can be further suppressed. The hydrogenation rate of the styrene-based elastomer is usually 100% or less.

The styrene-based elastomer preferably has a styrene content of 5% by weight or more and 40% by weight or less.
When the content of styrene contained in the styrene-based elastomer is within the above range, a sufficient amount of the phase-separated structure of the styrene segment can be formed, and the pressure-sensitive adhesive layer can be made more difficult to peel off from the base material layer. can. Further, when the styrene content is in the above range, sufficient adhesive strength can be exhibited. Further, when the styrene content is in the above range, the shape of the phase-separated structure can be easily made spherical. From the viewpoint of further promoting the formation of the phase-separated structure of the styrene segment and further suppressing the peeling of the pressure-sensitive adhesive layer from the base material layer, the more preferable lower limit of the styrene content of the styrene-based elastomer is 7% by weight, more preferable. The upper limit is 35% by weight.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but a preferable lower limit is 5 μm, a more preferable lower limit is 10 μm, a preferable upper limit is 800 μm, and a more preferable upper limit is 500 μm. When the thickness of the pressure-sensitive adhesive layer is within this range, the weight of the electronic component including the double-sided pressure-sensitive adhesive tape can be reduced, and the double-sided pressure-sensitive adhesive tape having sufficient adhesive strength and handleability can be obtained.

In a preferred embodiment of the present invention, the pressure-sensitive adhesive layer is made of petroleum-based, terpene-based, terpenephenol-based or rosin-based, and has a hydrogenation rate of preferably 95% or more, more preferably 96% or more. Contains fire.
By incorporating a tacky fire that satisfies the above type and hydrogenation rate in the pressure-sensitive adhesive layer, the adhesive strength of the double-sided pressure-sensitive adhesive tape can be further improved. The upper limit of the hydrogenation rate is usually 100% or less.

The pressure-sensitive adhesive layer may further contain additives such as a softening agent, an antioxidant, an anti-adhesive agent, and a mold release agent, if necessary.

The method for producing the double-sided adhesive tape of the present invention is not particularly limited, but it is preferably produced by the coextrusion laminating method. The co-extrusion lami method is a manufacturing method in which a base resin and an adhesive resin are extruded at the same time by a co-extruder to form a base layer and an adhesive layer at the same time. Since no solvent is used, an adherend using a residual solvent is used. The cost is low because there is no contamination and the double-sided adhesive tape can be manufactured in one process.
When the double-sided adhesive tape is manufactured by the coextrusion laminating method, a transition layer is formed between the base material layer and the adhesive layer. The transition layer refers to a layer in which the components of the base material layer and the components of the pressure-sensitive adhesive layer are gradually replaced as they proceed from the base material layer side to the pressure-sensitive adhesive layer side. The presence of the transition layer is determined by cutting out a cross section of the double-sided adhesive tape using a microtome, using it as a test sample for observation, and using a scanning probe microscope (SPM) to detect changes in hardness at the interface between the substrate layer and the adhesive layer. It can be confirmed by observing and continuously changing the hardness. It can also be confirmed by observing the change in the phase separation structure at the interface between the base material layer and the pressure-sensitive adhesive layer with a transmission electron microscope (TEM). For example, when the pressure-sensitive adhesive layer contains a styrene-based elastomer and has a phase-separated structure having spherical styrene segments in the molecule, the presence of a transition layer causes the spherical styrene segments in the pressure-sensitive adhesive layer to approach the substrate layer. As the size decreases, the density of spherical styrene segments decreases.

The use of the double-sided adhesive tape of the present invention is not particularly limited, but the double-sided adhesive tape can be peeled off without damaging the adherend by pulling the double-sided adhesive tape in a direction horizontal to the adhesive surface, so that sensors, battery packs, etc. can be recycled. It can be suitably used for fixing parts of electronic devices.
An electronic component having a double-sided adhesive tape of the present invention is also one of the present inventions.

According to the present invention, it is possible to provide a double-sided adhesive tape that has high adhesive strength and can be peeled off without damaging the adherend.

(A) It is a schematic diagram which showed the state of peeling a part from a double-sided adhesive tape. (B) It is a schematic diagram showing how the double-sided adhesive tape is pulled in the horizontal direction and peeled off. (C) It is a schematic diagram which showed the state which the conventional double-sided adhesive tape was pulled in the horizontal direction and peeled off. It is a schematic diagram which showed the state of the measurement of the 0 ° peel strength. It is a schematic diagram which showed the state of the measurement of the 180 ° peel strength.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(1) Base resin for the pressure-sensitive adhesive layer As the base resin for the pressure-sensitive adhesive layer, a resin synthesized by the following method and a commercially available product were used.
(Synthesis Example 1)
In a reaction vessel substituted with nitrogen, 500 parts by weight of degassed and dehydrated cyclohexane, 10 parts by weight of styrene and 5 parts by weight of tetrahydrofuran were charged, and 0.13 parts by weight of n-butyllithium was added at the polymerization initiation temperature of 40 ° C. Then, temperature-heating polymerization was carried out to obtain an aromatic alkenyl polymer block.
After the polymerization conversion of the aromatic alkenyl polymer block reaches approximately 100%, the reaction solution is cooled to 15 ° C., then 90 parts by weight of 1,3-butadiene as a conjugated diene compound is added, and further heating and polymerization is carried out. This was performed to obtain a conjugated diene polymer block.
After the polymerization conversion reached almost 100%, 0.03 part by weight of (chloromethyl) trichlorosilane as a coupling agent was added to the reaction vessel to carry out a coupling reaction. After the coupling reaction was completed, hydrogen gas was allowed to stand for 10 minutes while being supplied at a pressure of 0.4 MPa-Gauge to obtain a styrene-based elastomer. GPC analysis of a partially extracted styrene-based elastomer revealed that the weight average molecular weight was about 120,000, the dispersity was 1.4, and the coupling ratio (of the coupled copolymer among the entire copolymer). Content) was 60%. Moreover, when the infrared absorption spectrum of the partially taken out polymer was measured and calculated by the Morero method, the vinyl bond content was 80 mol%.
Then, 0.03 part by weight of diethylaluminum chloride and 0.06 part by weight of bis (cyclopentadienyl) titanium furfuryloxychloride were added to the reaction vessel, and the mixture was stirred. The hydrogenation reaction was started at a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80 ° C., and when the absorption of hydrogen was completed, the reaction solution was returned to normal temperature and pressure and removed from the reaction vessel to add hydrogen. Radial type styrene-based elastomer was obtained. The hydrogenation rate was measured by infrared absorption spectrum and found to be 98%.

(Synthesis Example 2)
In a reaction vessel substituted with nitrogen, 500 parts by weight of degassed and dehydrated cyclohexane, 20 parts by weight of styrene and 5 parts by weight of tetrahydrofuran were charged, and 0.13 parts by weight of n-butyllithium was added at the polymerization initiation temperature of 40 ° C. Then, temperature-heating polymerization was carried out to obtain an aromatic alkenyl polymer block.
After the polymerization conversion of the aromatic alkenyl polymer block reached approximately 100%, the reaction solution was cooled to 15 ° C., and then 65 parts by weight of 1,3-butadiene and 15 parts by weight of styrene were added as conjugated diene compounds. Further, thermal polymerization was carried out to obtain a conjugated diene polymer block.
After the polymerization conversion reached almost 100%, 0.06 part by weight of methyldichlorosilane was added as a coupling agent in the reaction vessel to carry out a coupling reaction. After the coupling reaction was completed, hydrogen gas was allowed to stand for 10 minutes while being supplied at a pressure of 0.4 MPa-Gauge to obtain a styrene-based elastomer. GPC analysis of a partially extracted styrene-based elastomer revealed that the weight average molecular weight was about 110,000, the dispersity was 1.4, and the coupling ratio (of the coupled copolymer among the entire copolymer). Content) was 60%. Moreover, when the infrared absorption spectrum of the partially taken out polymer was measured and calculated by the Morero method, the vinyl bond content was 80 mol%.
Then, 0.03 part by weight of diethylaluminum chloride and 0.06 part by weight of bis (cyclopentadienyl) titanium furfuryloxychloride were added to the reaction vessel, and the mixture was stirred. The hydrogenation reaction was started at a hydrogen gas supply pressure of 0.7 MPa-Gauge and a reaction temperature of 80 ° C., and when the absorption of hydrogen was completed, the reaction solution was returned to normal temperature and pressure and removed from the reaction vessel to add hydrogen. Triblock type styrene-based elastomer was obtained. The hydrogenation rate was measured by infrared absorption spectrum and found to be 98%.

(Commercial products 1 and 2)
The following products were used as commercial products 1 and 2.
-Commercial product 1: HSBR, DYNARON1321P, manufactured by JSR Corporation-Commercial product 2: SEBS, DYNARON9901P, manufactured by JSR Corporation

(2) Base resin for the base material layer The following materials were used as the base resin for the base material layer.
・ Α-Condient resin: Toughmer PN-2060, manufactured by Mitsui Chemicals, Inc. ・ Low density polyethylene resin: Evolu SP0540, manufactured by Prime Polymer Co., Ltd. ・ High density polyethylene resin: A140, manufactured by Asahi Kasei Co., Ltd. ・ Polypropylene resin: J715, manufactured by Prime Polymer Co., Ltd. Polybutylene terephthalate resin: 700FP, manufactured by Polyplastics ・ Polypropylene resin: Elastolan S80A, manufactured by BASF

(3) Adhesive (tacky fire)
The following pressure-sensitive adhesives were used as the pressure-sensitive adhesive to be blended in the pressure-sensitive adhesive layer.
・ Terpene phenol-based tackifier: YS Polystar UH115, manufactured by Yasuhara Chemical Co., Ltd. ・ Petroleum-based tackifier: Archon P-125, manufactured by Arakawa Chemical Co., Ltd. ・ Rosin-based tackifier: KE-359, manufactured by Arakawa Chemical Co., Ltd.

(4) Acrylic type 1 and 2, and PVB type (double-sided adhesive tape)
The following acrylics 1 and 2 and PVBs were used.
-Acrylic 1: Acrylic high-transparency double-sided tape, SSVK1-175, thickness 175 μm, manufactured by Sekisui Chemical Co., Ltd.-Acrylic 2: Double-sided tape for fixing acrylic LCD members, 3810BWH, thickness 100 μm, manufactured by Sekisui Chemical Co., Ltd. System: PVB normal interlayer film, S-LEC Clear Film, thickness 380 μm, manufactured by Sekisui Chemical Co., Ltd.

(Example 1)
To form a pressure-sensitive adhesive layer by mixing 100 parts by weight of the styrene-based elastomer obtained in Synthesis Example 1, 40 parts by weight of a terpenephenol-based pressure-sensitive adhesive, and 1 part by weight of an antioxidant (IRGANOX 1010, manufactured by BASF). A pressure-sensitive adhesive composition was obtained. The α-polyolefin resin is used as a raw material for the base material layer, the pressure-sensitive adhesive composition obtained above is used as the raw material for the pressure-sensitive adhesive layer, and a base material having a thickness of 33.3 μm is coextruded by the T-die method. A double-sided adhesive tape having a total thickness of 100 μm having an adhesive layer having a thickness of 33.3 μm on both sides of the layer was obtained. Further, a PET separator that had been mold-released on both sides before winding was laminating and wound to obtain a roll-shaped double-sided adhesive tape.

( Examples 2, 3, 5 to 7 , Comparative Examples 1 to 4 , Reference Example 1 )
A double-sided adhesive tape was obtained in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive layer and the base resin of the base material were as shown in Tables 1 and 2.

(Comparative Example 5)
The styrene-based elastomer obtained in Synthesis Example 1 was extruded to obtain a non-support type double-sided adhesive tape having a thickness of 100 μm. Both sides of the obtained double-sided adhesive tape were protected with a light release type release PET film until use.

(Comparative Example 6)
Acrylic type 1 (double-sided adhesive tape) was used.

(Comparative Example 7)
A PVB system (double-sided adhesive tape) was used.

(Comparative Example 8)
Acrylic 2 (double-sided adhesive tape) was used.

<Measurement of physical properties>
The following physical properties were measured for the double-sided adhesive tapes obtained in Examples and Comparative Examples. The results are shown in Tables 1 and 2.

(Measurement of tensile breaking strength and tensile breaking elongation)
Each of the obtained double-sided adhesive tapes was cut to a width of 10 mm to prepare a test piece. The obtained test piece was subjected to a tensile test using a tensile tester (RTG1310, manufactured by AND) under the conditions of a humidity of 23 ° C., a humidity of 50%, a sample chuck distance of 5 mm, and a speed of 300 mm / min. And the tensile elongation at break was measured.

(Measurement of 0 ° peel strength)
The obtained double-sided adhesive tape was cut into 25 mm × 30 mm. Next, as shown in FIG. 2, the portion of the double-sided adhesive tape 4 cut from one short side to the other short side up to 10 mm is formed by two stainless steel plates 5 (SUS304, SUS304, compliant with JIS G4305 and JIS B0601. The surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) was lightly temporarily crimped with a finger. After temporary crimping, a 2 kg rubber roller was reciprocated twice on the test piece at a speed of 300 mm / min to prepare a test piece for 0 ° peel strength evaluation. Further, the side opposite to the side on which the double-sided adhesive tape of both stainless steel plates 5 was sandwiched was sandwiched by the chuck 6. Then, using a tensile tester (RTG1250A, manufactured by AND), the double-sided adhesive tape 4 is pulled in a horizontal direction with the adhesive surface at a peeling speed of 300 mm / min at a temperature of 23 ° C and a humidity of 50% without bending, and peeled at 0 °. The strength (N / 25 mm) was measured.

(Measurement of 180 ° peel strength)
The obtained double-sided adhesive tape was cut into strips having a width of 24 mm to prepare test pieces. The test piece was placed on a stainless steel plate (SUS304, surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) conforming to JIS G4305 and JIS B0601 so that the adhesive layer faced the stainless steel plate. Next, the test piece and the stainless steel plate were bonded together by reciprocating a 2 kg rubber roller once on the test piece at a speed of 300 mm / min. Further, according to JIS Z0237, a polyethylene terephthalate film having a thickness of 25 μm called JIS C2318 is laminated on the test piece, and another 2 kg rubber roller is reciprocated on the film at a speed of 300 mm / min to make 180 °. It was used as a test sample for evaluation of peel strength. Then, using a tensile tester (RTG1250A, manufactured by AND), the mixture was allowed to stand at a temperature of 23 ° C. and a humidity of 50% for 24 hours, and a tensile test was performed in the 180 ° direction at a peeling speed of 300 mm / min according to JIS Z0237. , 180 ° peel strength (N / 25 mm) was measured.

(Phase separation structure)
The shape of the phase-separated structure was confirmed by observing the adhesive layer of the obtained double-sided adhesive tape with a transmission electron microscope JEM-2100 (manufactured by JEOL Ltd.). If the shape of the phase-separated structure was spherical, its size was measured.

(Presence / absence of transition layer)
The obtained double-sided adhesive tape was cut out from a cross section of the double-sided adhesive tape using a cryomicrotome (ULTRACUT, manufactured by LEICA) and used as a test sample for observation. The presence or absence of the transition layer was examined by observing the change in hardness of the interface between the base material layer and the pressure-sensitive adhesive layer with a scanning probe microscope (SPM: Dimension, manufactured by Bruker).

<Evaluation>
The adhesive tapes obtained in Examples and Comparative Examples were evaluated by the following methods.
The results are shown in Tables 1 and 2.

(1) Evaluation of peelability A laminated lithium-ion battery pack (hereinafter referred to as a battery pack) is attached to a smartphone housing (hereinafter referred to as a housing) whose surface is SUS via a double-sided adhesive tape obtained. Attached. Then, as shown in the left figure of FIG. 1 (b), the double-sided adhesive tape was peeled off so as to be displaced in the direction parallel to the adhesive surface while fixing the housing and the battery pack on the side surfaces. Using 10 samples, this operation was repeated 10 times to test the peelability. Visually observe the battery pack after peeling, and if there is no damage and the double-sided adhesive tape is not torn and can be peeled 10 times, it is "S", if it is 9 times, it is "A". "B" if it was 8 times, "C" if it was 1 to 7 times, and "D" if the double-sided adhesive tape was torn and there was only what was left in the housing and battery pack. The peelability was evaluated as.

(2) Evaluation of Residual Solvent The amount of residual solvent was measured with FV-250 manufactured by HORIBA, Ltd. using the hydrogen flame ionization method (FID method). The residual solvent was evaluated as "◯" when no residual solvent was detected (less than 1 ppm) and "x" when a residual solvent was detected.

(3) Evaluation of adhesive residue The housing after evaluation of peelability was observed with an optical microscope, and the adhesive residue was evaluated as "○" when there was no adhesive residue and "×" when there was adhesive residue. ..

According to the present invention, it is possible to provide a double-sided adhesive tape that has high adhesive strength and can be peeled off without damaging the adherend.

1 Double-sided adhesive tape 2 Parts 3 Board 4 Double-sided adhesive tape 5 Stainless steel plate 6 Chuck

Claims (6)

A double-sided adhesive tape having adhesive layers on both sides of the base material layer.
The tensile breaking strength of the double-sided adhesive tape is 10 MPa or more, and the double-sided adhesive tape has a tensile breaking strength of 10 MPa or more.
The double-sided adhesive tape has a tensile elongation at break of 1000% or more.
The tensile breaking strength of the double-sided adhesive tape is higher than the 0 ° peel strength of peeling the double-sided adhesive tape sandwiched between two stainless steel plates in a direction horizontal to the adhesive surface without bending.
The 0 ° peel strength is lower than the 180 ° peel strength for the stainless steel plate.
The base material layer contains at least one selected from the group consisting of an α-olefin copolymer and polyurethane.
The pressure-sensitive adhesive layer is a double-sided pressure-sensitive adhesive tape containing a styrene-based elastomer, and the styrene-based elastomer has a spherical styrene segment having a diameter of 5 nm or more due to internal phase separation . The double-sided adhesive tape according to claim 1, wherein the base material layer contains an α-olefin copolymer . The double-sided adhesive tape according to claim 1 or 2 , wherein the styrene-based elastomer has a hydrogenation rate of 95% or more and a styrene content of 5% by weight or more and 40% by weight or less. The double-sided adhesive tape according to claim 1, 2 or 3 , wherein the pressure-sensitive adhesive layer is composed of petroleum-based, terpene-based, terpene-phenol-based or rosin-based and contains a tacky fire having a hydrogenation rate of 95% or more. The double-sided adhesive tape according to claim 1, 2, 3 or 4 , which has a transition layer between the base material layer and the pressure-sensitive adhesive layer. An electronic component having the double-sided adhesive tape according to claim 1, 2, 3, 4 or 5 .

Images