JP2019119760A - Double-sided adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided adhesive tape which has a high adhesive force and can be peeled off without damaging an adherend. A double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of a base material layer, wherein the double-sided pressure-sensitive adhesive tape has a tensile breaking strength of 10 MPa or more, and the double-sided pressure-sensitive adhesive tape has a tensile breaking elongation of 1,000% or more. Yes, the tensile breaking strength of the double-sided adhesive tape is higher than the 0° peel strength at which the double-sided adhesive tape sandwiched between two stainless steel plates is peeled in a direction parallel to the adhesive surface without bending, and the 0° peel strength is higher. Is a double-sided adhesive tape having a peel strength lower than 180° with respect to the stainless steel plate. [Selection diagram] None

Description

The present invention relates to a double-sided pressure-sensitive adhesive tape which can be peeled without damaging an adherend while having high adhesive strength.

In a portable electronic device (for example, a mobile phone, a portable information terminal or the like) equipped with an image display device or an input device, a double-sided adhesive tape is used for assembly. Specifically, for example, a cover panel for protecting the surface of the portable electronic device is adhered to the touch panel module or the display panel module, or the touch panel module and the display panel module are adhered, or a sensor or a battery pack is fixed. Double-sided pressure-sensitive adhesive tapes have been used for the purpose of reducing the size (for example, Patent Documents 1 and 2). Moreover, a double-sided adhesive tape is used also for the use which fixes vehicle components (for example, vehicle-mounted panel) to a vehicle main body.

JP, 2009-242541, A JP, 2009-258274, A

2. Description of the Related Art Conventionally, discarded electronic devices are recycled after reusable parts such as sensors and battery packs are taken out before final disposal. However, when the parts to be collected are fixed by the double-sided pressure-sensitive adhesive tape, there is a problem that the parts may be damaged if they are separated from the double-sided pressure-sensitive adhesive tape and collected.

For example, when recovering a part fixed to a substrate by a double-sided adhesive tape, the end of the part is usually lifted and peeled off from the double-sided adhesive tape as shown in the left view of FIG. 1 (a). However, if such a peeling method is performed with parts that have been miniaturized or thinned in recent years, the parts may be damaged without being able to withstand the force at the time of peeling as shown in FIG. There was a problem that. In order to solve this problem, as shown in FIG. 1 (b), it has been considered to pull the double-sided adhesive tape in the horizontal direction and peel off, but in the case of the conventional double-sided adhesive tape, double-sided adhesive as shown in FIG. 1 (c) There is a problem that the tape may be broken without being able to withstand horizontal force, and may remain in parts, or only part of the double-sided adhesive tape may be removed. In particular, the double-sided pressure-sensitive adhesive tape used for fixing parts has high adhesive strength since it is necessary to fix the parts securely, and the double-sided pressure-sensitive adhesive tape is more easily broken.

An object of the present invention is to provide a double-sided pressure-sensitive adhesive tape which can be peeled without damaging the adherend while having high adhesive strength, in view of the above-mentioned current situation.

The present invention is a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides of a substrate layer, wherein the tensile breaking strength of the double-sided pressure-sensitive adhesive tape is 10 MPa or more, and the tensile breaking elongation of the double-sided pressure-sensitive adhesive tape is 1000% or more The tensile breaking strength of the double-sided pressure-sensitive adhesive tape is higher than the 0 ° peeling strength by which the double-sided pressure-sensitive adhesive tape sandwiched between two stainless steel plates is peeled off in the direction horizontal to the bonding surface without bending. Is a double-sided pressure-sensitive adhesive tape lower than the 180 ° peel strength to the stainless steel plate.
The present invention will be described in detail below.

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

The double-sided pressure-sensitive adhesive tape of the present invention has a tensile breaking strength of 10 MPa or more.
When the tensile strength at break of the double-sided pressure-sensitive adhesive tape is 10 MPa or more, even when the double-sided pressure-sensitive adhesive tape is pulled in a direction horizontal to the bonding surface and peeled off, the double-sided tape can be prevented from being broken. From the viewpoint of further suppressing breakage 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 said tensile breaking strength can be adjusted with the kind of base material. The tensile breaking strength is measured by performing a tensile test under the conditions of a measurement temperature of 23 ° C. and a humidity of 50%, a distance between chucks of the sample of 5 mm, and a speed of 300 mm / min according to JIS K7161. can do.

The double-sided pressure-sensitive adhesive tape of the present invention has a tensile elongation at break of 1000% or more.
When the tensile elongation at break of the double-sided pressure-sensitive adhesive tape is 1000% or more, even when the double-sided pressure-sensitive adhesive tape is pulled in a direction horizontal to the bonding surface and peeled off, the double-sided tape can be prevented from breaking. From the viewpoint of being able to further suppress breakage 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 said tensile elongation at break can be adjusted with the kind of base material. The tensile elongation at break is measured using a tensile tester in accordance with JIS K7161-2, and a tensile test is performed 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

The double-sided pressure-sensitive adhesive tape of the present invention has a tensile breaking strength higher than the 0 ° peel strength in which the double-sided pressure-sensitive adhesive tape sandwiched between two stainless steel plates is peeled off in the direction horizontal to the bonding surface without bending.
The tensile breaking strength of the double-sided pressure-sensitive adhesive tape is higher than 0 ° peel strength, so that the double-sided tape can be prevented from being broken even when the double-sided pressure-sensitive adhesive tape is pulled in a direction horizontal to the bonding 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, a portion from the one short side to the other short side of the double-sided pressure-sensitive adhesive tape 4 cut to 10 mm is made of two stainless steel plates 5 (SUS304, JIS G4305 and JIS B0601). Lightly pre-crimped with a finger to surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm). After temporary pressure bonding, a 2 kg rubber roller is reciprocated twice on the test piece at a speed of 300 mm / min to make a test sample for evaluation of 0 ° peel strength. Further, the side opposite to the side sandwiching the double-sided adhesive tape of both stainless steel plates 5 is sandwiched by the chuck 6. Thereafter, the double-sided pressure-sensitive adhesive tape 4 is not bent at a temperature of 23 ° C. and a humidity of 50%, pulled in a direction horizontal to the bonding surface at a peeling speed of 300 mm / min, and the force required for peeling is measured.

In the double-sided pressure-sensitive adhesive tape of the present invention, the 0 ° peel strength is lower than the 180 ° peel strength against the stainless steel plate.
Since the 0 ° peel strength is lower than the 180 ° peel strength to the stainless steel plate used for the 0 ° peel strength measurement, the adherend can be reliably fixed until the double-sided pressure-sensitive adhesive tape is peeled off and Even when the tape is pulled in a direction horizontal to the adhesive surface and peeled off, the double-sided tape can be prevented from being broken. The 180 ° peel strength is, as shown in FIG. 3, affixing the double-sided pressure-sensitive adhesive tape 4 to the stainless steel plate 5, bending the end of the double-sided pressure-sensitive adhesive tape 4 180 °, pulling it, and measuring the force required to peel off. It can be determined by More specifically, it can be measured by the following method.
The double-sided pressure-sensitive adhesive tape is cut into a strip having a width of 24 mm to prepare a test piece. Next, the test piece is placed on a stainless steel plate (SUS 304, surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) in accordance with JIS G4305 and JIS B0601 so that the adhesive layer faces the stainless steel plate . Thereafter, the test piece and the stainless steel plate are attached to each other by reciprocating a 2 kg rubber roller once at a speed of 300 mm / min on the test piece. Furthermore, according to JIS Z0237, a polyethylene terephthalate film specified in JIS C2318 with a thickness of 25 μm is stacked on a test piece, and 180 ° peeling is performed by causing another 2 kg rubber roller to reciprocate at a speed of 300 mm / min. Make a test sample for strength evaluation. Thereafter, the sample is allowed to stand at a temperature of 23 ° C. and a humidity of 50% for 24 hours, and a tensile test of 180 ° direction is performed at a peeling speed of 300 mm / min according to JIS Z0237 to measure 180 ° peel strength (N / 25 mm).

The raw material of the said base material layer will not be specifically limited if the said tensile breaking strength and the said tensile breaking elongation are satisfy | filled. As a base material which satisfy | fills the said tensile breaking strength and the said tensile breaking elongation, polyethylene, an alpha-olefin copolymer, a polyurethane, a styrene-type elastomer etc. are mentioned, for example. Above all, at least one selected from the group consisting of polyethylene, α-olefin copolymer and polyurethane, since it becomes a double-sided pressure-sensitive adhesive tape which is further excellent in tensile breaking strength and tensile breaking elongation. It is preferable to contain the above, and it is more preferable that it is an alpha-olefin copolymer. The raw material of the said base material layer may be only 1 type, and 2 or more types may be sufficient as it.

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. By the thickness of the said base material being more than the said minimum, the intensity | strength sufficient of the double-sided adhesive tape obtained will improve, and it will become difficult to tear off in the case of peeling. The upper limit of the thickness of the base material layer is not particularly limited, but is preferably 1 mm or less. The electronic component containing the said double-sided adhesive tape can be reduced in weight because the thickness of the said base material is below the said upper limit, and also it can be set as the double-sided adhesive tape excellent in the softness | flexibility and the handleability.

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

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 Copolymer (SEP), styrene ethylene butylene block copolymer (SEB), styrene-isoprene block copolymer (SI), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene block copolymer ( SB), styrene-butadiene-styrene block copolymer (SBS) and the like. Among these, SEPS and SEBS are particularly preferable because the shape of a styrene segment described later tends to be spherical.

The styrenic elastomer preferably has a spherical styrene segment having a diameter of 5 nm or more due to intramolecular phase separation.
A styrenic elastomer comprises a rubber segment exhibiting rubber elasticity and a styrene segment serving as a pseudo-crosslinking point of the rubber segment, and the rubber segment and the styrene segment have low compatibility, so the rubber segment and the styrene segment It is a non-uniform phase separation structure which 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 the base material having a high SP value is used. Since the styrene segment interacts with the substrate, the adhesion between the pressure-sensitive adhesive layer and the substrate layer can be improved. As a result, it becomes difficult to peel off the pressure-sensitive adhesive layer from the base material layer, and it becomes difficult to leave an adhesive on the adherend. From the viewpoint of suppression of peeling of the pressure-sensitive adhesive layer from the base material and further suppression of adhesive residue on the adherend, a more preferable lower limit of the above diameter is 6 nm. The upper limit of the diameter is not particularly limited, but the upper limit is 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, and more preferably 96% or more, from the viewpoint of being able to further suppress the contamination of the adherend. Contamination of the adherend can be further suppressed by setting the hydrogenation rate of the styrene-based elastomer to the above lower limit or more. 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 to 40% by weight.
When the content of styrene contained in the styrene-based elastomer is in the above-mentioned range, a phase separation structure of a sufficient amount of styrene segments can be formed, and the pressure-sensitive adhesive layer can be more hardly peeled off from the base material layer it can. Moreover, sufficient adhesiveness can be expressed by being styrene content of the said range. Furthermore, the shape of the phase separation structure can be easily made spherical by using the styrene content in the above range. From the viewpoint of further promoting the formation of the phase separation structure of the styrene segment and further suppressing the peeling of the pressure-sensitive adhesive layer from the base layer, the lower limit of the styrene content of the above-mentioned styrene elastomer is more preferably 7% by weight, more preferably 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 in this range, the weight of the electronic component including the double-sided pressure-sensitive adhesive tape can be reduced, and a double-sided pressure-sensitive adhesive tape having sufficient adhesive strength and handling can be obtained.

In a preferred embodiment of the present invention, the pressure-sensitive adhesive layer is made of petroleum, terpene, terpene phenol or rosin and has a hydrogenation rate of preferably 95% or more, more preferably 96% or more. Contains a fire.
The tackiness of the double-sided pressure-sensitive adhesive tape can be further improved by incorporating a tacky fire in the pressure-sensitive adhesive layer so as to satisfy the type and the hydrogenation rate. In addition, the upper limit of the said hydrogenation rate is 100% or less normally.

The pressure-sensitive adhesive layer may further contain additives such as a softener, an antioxidant, an anti-adhesion agent, a release agent, and the like, if necessary.

Although the manufacturing method of the double-sided adhesive tape of this invention is not specifically limited, It is preferable to manufacture by the co-extrusion lamination method. The co-extrusion lamination method is a manufacturing method in which the base material layer and the pressure-sensitive adhesive layer are simultaneously formed by extruding the base resin and the pressure-sensitive adhesive resin with a co-extruder. The cost is low because the double-sided adhesive tape can be manufactured in one step.
In addition, when a double-sided adhesive tape is manufactured by the co-extrusion lamination method, a transfer layer is formed between the said base material layer and the said adhesive layer. The transfer layer refers to a layer in which the component of the base layer and the component of the pressure-sensitive adhesive layer are gradually replaced as it proceeds from the base layer side to the pressure-sensitive adhesive layer side. The presence of the above-mentioned transfer layer cuts out the cross section of the double-sided adhesive tape using a microtome, makes it a test sample for observation, and changes the hardness at the interface between the substrate layer and the pressure-sensitive adhesive layer with a scanning probe microscope (SPM). It can be observed and confirmed by a continuous change in hardness. Moreover, it can confirm also by observing the change of the phase-separation structure of the interface of a base material layer and an adhesive layer with a transmission electron microscope (TEM). For example, in the case where the pressure-sensitive adhesive layer contains a styrenic elastomer and has a phase separation structure having spherical styrene segments in the molecule, the spherical styrene segments in the pressure-sensitive adhesive layer approach the base layer when the transition layer is present. The size decreases as the size decreases, and the density of spherical styrene segments decreases.

Although the application of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, it can be peeled off without damaging the adherend by pulling the double-sided pressure-sensitive adhesive tape in a direction horizontal to the adhesive surface. It can use suitably for the use which fixes the parts of electronic equipment.
An electronic component having the double-sided pressure-sensitive adhesive tape of the present invention is also one of the present invention.

According to the present invention, it is possible to provide a double-sided pressure-sensitive adhesive tape which can be peeled without damaging the adherend while having high adhesive strength.

(A) It is the schematic diagram which showed a mode that components were peeled from a double-sided adhesive tape. (B) It is the model which showed a mode that the double-sided adhesive tape was pulled in the horizontal direction and it peeled. (C) It is the model which showed a mode that the conventional double-sided adhesive tape was pulled in the horizontal direction, and was peeled. It is a schematic diagram which showed the mode of the measurement of 0 degree peeling strength. It is a schematic diagram which showed the mode of the measurement of 180 degree peeling strength.

EXAMPLES The embodiments of the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

(1) Base resin of pressure-sensitive adhesive layer A resin synthesized by the following method and a commercially available product were used as the base resin of the pressure-sensitive adhesive layer.
Synthesis Example 1
In a nitrogen-substituted reaction vessel, 500 parts by weight of degassed and dehydrated cyclohexane, 10 parts by weight of styrene and 5 parts by weight of tetrahydrofuran are charged, and 0.13 parts by weight of n-butyllithium is added at 40 ° C. as a polymerization initiation temperature. Then, the temperature was raised for polymerization to obtain an aromatic alkenyl polymer block.
After the polymerization conversion of the aromatic alkenyl polymer block reaches about 100%, the reaction solution is cooled to 15 ° C., 90 parts by weight of 1,3-butadiene as a conjugated diene compound is then added, and the temperature rising polymerization is further carried out Conducted to obtain a conjugated diene polymer block.
After the polymerization conversion reached about 100%, 0.03 parts 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, it was allowed to stand for 10 minutes while supplying hydrogen gas at a pressure of 0.4 MPa-gauge to obtain a styrenic elastomer. According to GPC analysis of the partially taken out styrenic elastomer, the weight average molecular weight is about 120,000, the degree of dispersion is 1.4, and the coupling ratio (of the coupled copolymer out of the entire copolymer) The content was 60%. Moreover, when the infrared absorption spectrum of the polymer partially taken out was measured and calculated by the Morelo method, the vinyl bond content was 80 mol%.
Thereafter, 0.03 parts by weight of diethylaluminum chloride and 0.06 parts by weight of bis (cyclopentadienyl) titanium furfuryl oxychloride were added to the reaction vessel and stirred. The hydrogen addition reaction is started at a hydrogen gas supply pressure of 0.7 MPa-Gauge at a reaction temperature of 80 ° C, and when absorption of hydrogen is completed, the reaction solution is returned to normal temperature and pressure and removed from the reaction vessel, thereby adding hydrogen. The radial type styrenic elastomer of It was 98% when the hydrogenation rate was measured by the infrared absorption spectrum.

(Composition example 2)
In a nitrogen-substituted reaction vessel, 500 parts by weight of degassed and dehydrated cyclohexane, 20 parts by weight of styrene and 5 parts by weight of tetrahydrofuran are charged, and 0.13 parts by weight of n-butyllithium is added at 40 ° C. as a polymerization initiation temperature. Then, the temperature was raised for polymerization to obtain an aromatic alkenyl polymer block.
After the polymerization conversion of the aromatic alkenyl polymer block reaches about 100%, the reaction solution is cooled to 15 ° C., and then 65 parts by weight of 1,3-butadiene and 15 parts by weight of styrene as a conjugated diene compound are added, Further, the temperature was raised for polymerization to obtain a conjugated diene polymer block.
After the polymerization conversion reached almost 100%, 0.06 parts by weight of methyldichlorosilane as a coupling agent was added to the reaction vessel to carry out a coupling reaction. After the coupling reaction was completed, it was allowed to stand for 10 minutes while supplying hydrogen gas at a pressure of 0.4 MPa-gauge to obtain a styrenic elastomer. According to GPC analysis of the partially taken out styrenic elastomer, the weight-average molecular weight is about 110,000, the degree of dispersion is 1.4, and the coupling ratio (of the coupled copolymer out of the entire copolymer) The content was 60%. Moreover, when the infrared absorption spectrum of the polymer partially taken out was measured and calculated by the Morelo method, the vinyl bond content was 80 mol%.
Thereafter, 0.03 parts by weight of diethylaluminum chloride and 0.06 parts by weight of bis (cyclopentadienyl) titanium furfuryl oxychloride were added to the reaction vessel and stirred. The hydrogen addition reaction is started at a hydrogen gas supply pressure of 0.7 MPa-Gauge at a reaction temperature of 80 ° C, and when absorption of hydrogen is completed, the reaction solution is returned to normal temperature and pressure and removed from the reaction vessel, thereby adding hydrogen. The triblock-type styrenic elastomer of It was 98% when the hydrogenation rate was measured by the infrared absorption spectrum.

(Commercial item 1 and 2)
The following were used as commercial products 1 and 2.
· Commercially available product 1: HSBR, DYNARON 1321P, manufactured by JSR · Commercially available product 2: SEBS, DYNARON9901P, manufactured by JSR

(2) Base resin of base layer The following were used as base resin of base layer.
Α-polyolefin resin: Tafmer PN-2060, Mitsui Chemicals, Inc. Low density polyethylene resin: Evolue SP 0540, Prime Polymer Co., Ltd. High density polyethylene resin: A140, Asahi Kasei Corp. Polypropylene resin: J715, Prime Polymer Co., Ltd. Polybutylene terephthalate resin: 700FP, manufactured by Polyplastics Co. · Polyurethane resin: Erastran S80A, manufactured by BASF

(3) Tackifier (Tackie fire)
The tackifier used in the pressure-sensitive adhesive layer was as follows.
Terpene phenol-based tackifier: YS Polystar UH115, manufactured by Yashara Chemical Co., Ltd. Petroleum-based tackifier: Alcon P-125, manufactured by Arakawa Chemical Co., Ltd. Rosin-based tackifier: KE-359, manufactured by Arakawa Kagaku Co.

(4) Acrylic type 1 and 2 and PVB type (double-sided adhesive tape)
The following were used as acrylic type 1 and 2 and PVB type | system | group.
Acrylic 1: High acrylic double-sided acrylic tape, SSV K1-175, thickness 175 μm, manufactured by Sekisui Chemical Co., Ltd. Acrylic 2: Double-sided tape for fixing acrylic LCD members, 3810 BWH, thickness 100 μm, Sekisui Chemical Co., Ltd. PVB System: PVB normal interlayer, S-LEC Clear Film, 380 μm thickness, Sekisui Chemical Co., Ltd.

Example 1
100 parts by weight of the styrene-based elastomer obtained in Synthesis Example 1, 40 parts by weight of a terpene phenol-based tackifier, and 1 part by weight of an antioxidant (IRGANOX 1010, manufactured by BASF) to form a pressure-sensitive adhesive layer An adhesive composition was obtained. A base material having a thickness of 33.3 μm by co-extrusion molding using the above-described α-polyolefin resin as a raw material of the base layer and the pressure-sensitive adhesive composition obtained above as a raw material of the pressure-sensitive adhesive layer by T-die method A 100 μm-thick double-sided adhesive tape having a 33.3 μm-thick adhesive layer on both sides of the layer was obtained. In addition, before being wound up, a PET separator subjected to release treatment on both sides was laminated and wound up to obtain a roll-shaped double-sided pressure-sensitive adhesive tape.

(Examples 2 to 7, Comparative Examples 1 to 4)
A double-sided pressure-sensitive 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 substrate were as shown in Tables 1 and 2.

(Comparative example 5)
By extruding the styrenic elastomer obtained in Synthesis Example 1, a 100 μm-thick non-support type double-sided pressure-sensitive adhesive tape was obtained. The obtained double-sided pressure-sensitive adhesive tape was protected on both sides with a light release type release PET film until use.

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

(Comparative example 7)
The 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 pressure-sensitive 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 obtained double-sided pressure-sensitive adhesive tape was cut to a width of 10 mm to prepare a test piece. Using the tensile tester (RTG 1310, manufactured by AND), the obtained test pieces are subjected to a tensile test under the conditions of 23 ° C. humidity 50%, sample chuck distance 5 mm, speed 300 mm / min. And the tensile elongation at break was measured.

(Measurement of 0 ° peel strength)
The obtained double-sided pressure-sensitive adhesive tape was cut into 25 mm × 30 mm. Next, as shown in FIG. 2, a portion from the one short side to the other short side of the double-sided pressure-sensitive adhesive tape 4 cut to 10 mm is made of two stainless steel plates 5 (SUS304, JIS G4305 and JIS B0601). The surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) was lightly pre-crimped with a finger. After temporary pressure bonding, a test piece for evaluation of 0 ° peel strength was prepared by reciprocating 2 kg of a rubber roller twice at a speed of 300 mm / min on the test piece. Further, the side opposite to the side sandwiching the double-sided adhesive tape of both stainless steel plates 5 was sandwiched by the chuck 6. Thereafter, using a tensile tester (RTG 1250A, manufactured by AND), the double-sided pressure-sensitive adhesive tape 4 is not bent at 23 ° C. and 50% humidity but pulled at a peeling speed of 300 mm / min. The strength (N / 25 mm) was measured.

(Measurement of 180 ° peel strength)
The obtained double-sided pressure-sensitive adhesive tape was cut into a strip of 24 mm width to prepare a test piece. The test piece was placed on a stainless steel plate (SUS304, surface finish BA, surface roughness 50 nm, size 50 mm × 125 mm) according to JIS G4305 and JIS B0601 so that the pressure-sensitive adhesive layer faced the stainless steel plate. Next, the test piece and the stainless steel plate were attached to each other by reciprocating a 2 kg rubber roller once at a speed of 300 mm / min on the test piece. Furthermore, according to JIS Z 0237, a polyethylene terephthalate film specified in JIS C 2318 having a thickness of 25 μm called a test piece is overlapped, and 180 degrees by causing another 2 kg rubber roller to reciprocate at a speed of 300 mm / min. It was used as a test sample for evaluation of peel strength. Thereafter, using a tensile tester (RTG 1250A, manufactured by AND), the substrate 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 180 ° peel strength (N / 25 mm) were measured.

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

(With or without transition layer)
The obtained double-sided pressure-sensitive adhesive tape was cut out of a cross section of the double-sided pressure-sensitive 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 pressure-sensitive 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 via a double-sided pressure-sensitive adhesive tape obtained on a smartphone case (hereinafter referred to as a case) having a surface of SUS peelability. I put it. Next, as shown in the left view of FIG. 1B, the double-sided adhesive tape was peeled off in a direction parallel to the bonding surface while fixing the housing and the battery pack on the side. This operation was repeated ten times using ten samples, and the peelability test was performed. The battery pack after peeling was visually observed, there was no damage, and the double-sided adhesive tape was not broken even ten times was able to peel "S" when it was nine times, "A", "B" when it was 8 times, "C" when it was 1 to 7 times, "D" when the double-sided adhesive tape was shredded and there were only those left in the case and battery pack Peelability was evaluated as.

(2) Evaluation of residual solvent The amount of the residual solvent was measured with FV-250 manufactured by Horiba, Ltd. using a hydrogen flame ionization method (FID method). The residual solvent was evaluated by setting the case where "residual solvent" was not detected (less than 1 ppm) as "O", and the case where residual solvent was detected as "x".

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

According to the present invention, it is possible to provide a double-sided pressure-sensitive adhesive tape which can be peeled without damaging the adherend while having high adhesive strength.

1 double-sided adhesive tape 2 parts 3 substrate 4 double-sided adhesive tape 5 stainless steel plate 6 chuck

Claims (7)

A double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides of a substrate layer,
The tensile breaking strength of the double-sided pressure-sensitive adhesive tape is 10 MPa or more.
The tensile elongation at break of the double-sided pressure-sensitive adhesive tape is 1000% or more,
The tensile breaking strength of the double-sided pressure-sensitive adhesive tape is higher than the 0 ° peeling strength by which the double-sided pressure-sensitive adhesive tape sandwiched between two stainless steel plates is peeled off in the direction parallel to the bonding surface without bending.
The double-sided pressure-sensitive adhesive tape, wherein the 0 ° peel strength is lower than the 180 ° peel strength against the stainless steel plate. The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the base material layer contains at least one or more selected from the group consisting of polyethylene, α-olefin copolymer and polyurethane. The double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the pressure-sensitive adhesive layer contains a styrenic elastomer, and the styrenic elastomer has a spherical styrene segment having a diameter of 5 nm or more by intramolecular phase separation. The double-sided pressure-sensitive adhesive tape according to claim 3, 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 pressure-sensitive adhesive tape according to claim 1, 2, 3 or 4, wherein the pressure-sensitive adhesive layer comprises a petroleum-based, terpene-based, terpene-phenol-based or rosin-based tacky fire having a hydrogenation rate of 95% or more. The double-sided pressure-sensitive adhesive tape according to claim 1, comprising a transfer layer between the substrate layer and the pressure-sensitive adhesive layer. The electronic component which has a double-sided adhesive tape of Claim 1, 2, 3, 4, 5 or 6.

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