JP7036715B2 - Double-sided adhesive tape - Google Patents

Description

The present invention relates to a double-sided adhesive tape having excellent stress relaxation and impact resistance and excellent reworkability on both adhesive surfaces.

In portable electronic devices such as mobile phones and personal digital assistants (PDAs), double-sided adhesive tapes are used for assembly (for example, Patent Documents 1 and 2). Double-sided adhesive tapes are also used for fixing in-vehicle electronic device parts such as in-vehicle panels to the vehicle body.

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

High adhesive strength is required for double-sided adhesive tapes used for fixing portable electronic device parts, in-vehicle electronic device parts, and the like. Furthermore, in recent years, the shapes of portable electronic devices, in-vehicle electronic devices, etc. tend to become more complicated as the functions become higher, so double-sided adhesive tape should be attached to steps, corners, non-planar parts, etc. There is. In such a case, since the double-sided adhesive tape is fixed in a deformed state, a force to return to the original shape, that is, a restoring force or a repulsive force acts, and the double-sided adhesive tape may peel off with the passage of time. rice field. In particular, when fixing a part in a deformed state, the part itself tries to return to its original shape, which exerts a restoring force and a repulsive force on the double-sided adhesive tape, resulting in insufficient fixing or double-sided adhesive tape. It sometimes peeled off. In order to prevent peeling due to such restoring force and repulsive force, the double-sided adhesive tape is required to have excellent stress relaxation properties. In addition, the double-sided adhesive tape is sometimes required to have impact resistance.

As a double-sided adhesive tape having excellent stress relaxation and impact resistance, a double-sided adhesive tape using a foam base material is known. However, with the conventional double-sided adhesive tape using a foam base material, when it is used for temporary fixing or when it is desired to peel off after bonding for some reason, the foam base material cracks at the time of peeling and adheres. There is a problem that the residue may remain on the body and the reworkability is inferior. In particular, in the double-sided adhesive tape, reworkability on both adhesive surfaces has been required.

An object of the present invention is to provide a double-sided adhesive tape having excellent stress relaxation and impact resistance and excellent reworkability on both adhesive surfaces.

The present invention is a double-sided adhesive tape having a foam base material and a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of the foam base material, respectively, the foam base material and the first. Both sides having a first resin layer and a second resin layer having a tensile breaking point stress of 4 MPa or more, respectively, between the pressure-sensitive adhesive layers and between the foam base material and the second pressure-sensitive adhesive layer. Adhesive tape.
The present invention will be described in detail below.

The present inventors have a foam base material and a first pressure-sensitive adhesive in a double-sided pressure-sensitive adhesive tape having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of the foam base material and the foam base material, respectively. A first resin layer and a second resin layer having a tensile breaking point stress of a certain value or more were arranged between the layers and between the foam base material and the second pressure-sensitive adhesive layer, respectively. The present inventors have adopted a foam base material capable of exhibiting excellent stress relaxation and impact resistance by arranging such a first resin layer and a second resin layer, while adopting both adhesive surfaces. The present invention has been completed by finding that it can exhibit excellent reworkability.

FIG. 1 shows a schematic diagram showing an example of a double-sided adhesive tape according to an embodiment of the present invention. The double-sided adhesive tape 1 according to an embodiment of the present invention of FIG. 1 has a first pressure-sensitive adhesive layer 31 and a second pressure-sensitive adhesive layer 32 on both sides of a foam base material 2. The first resin layer 41 is arranged between the foam base material 2 and the first pressure-sensitive adhesive layer 31, and the second resin is placed between the foam base material 2 and the second pressure-sensitive adhesive layer 32. Layer 42 is arranged.

The double-sided adhesive tape according to an embodiment of the present invention has a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of the foam base material and the foam base material, respectively.
By using the foam base material, the double-sided adhesive tape according to one embodiment of the present invention can exhibit excellent stress relaxation and impact resistance. The foam base material may have an open cell structure or a closed cell structure, but it is preferable to have an open cell structure. By using a foam base material having an open cell structure, more excellent stress relaxation and impact resistance can be exhibited. The foam base material may have a single-layer structure or a multi-layer structure.

The foam base material is not particularly limited, and examples thereof include polyurethane foams, polyolefin foams, rubber-based resin foams, and acrylic foams. Among them, a polyurethane foam or a polyolefin foam is preferable because it is easy to form an open cell structure and can exhibit excellent stress relaxation and impact resistance.

The density of the foam base material is not particularly limited, but the preferred lower limit is 0.03 g / cm ³ and the preferred upper limit is 0.8 g / cm ³ . By setting the density of the foam base material within this range, excellent stress relaxation and impact resistance can be exhibited while maintaining the strength of the double-sided adhesive tape. From the viewpoint of the strength, stress relaxation property and impact resistance of the double-sided adhesive tape, the more preferable lower limit is 0.1 g / cm ³ , the more preferable upper limit is 0.7 g / cm ³ , and the more preferable lower limit is 0. .15 g / cm ³ , a more preferred upper limit is 0.5 g / cm ³ , a particularly preferred lower limit is 0.2 g / cm ³ , and a particularly preferred upper limit is 0.4 g / cm ³ .
The density can be measured using an electronic hydrometer (for example, "ED120T" manufactured by Mirage Co., Ltd.) in accordance with JIS K 6767.

The 25% compressive strength of the foam substrate is not particularly limited, but a preferable lower limit is 1 kPa and a preferable upper limit is 100 kPa. By setting the 25% compressive strength of the foam base material within this range, excellent stress relaxation resistance and impact resistance can be exhibited while maintaining the strength of the double-sided adhesive tape. From the viewpoint of further improving the strength, stress relaxation property and impact resistance of the double-sided adhesive tape, the more preferable lower limit of the 25% compressive strength of the base material is 3 kPa, the more preferable upper limit is 50 kPa, the further preferable lower limit is 5 kPa, and further. The preferred upper limit is 40 kPa.
The 25% compressive strength can be obtained by measuring in accordance with JIS K 6254.

The shear storage elastic modulus of the foam substrate is not particularly limited, but the frequency in the master curve measured by a dynamic viscoelastic device and synthesized at a reference temperature of 23 ° C. is 1.0 × 10 ^-4 to 1.0 × 10 ⁻ . The maximum value of the shear storage elastic modulus in the ⁵ Hz region is preferably 1.0 × 10 ⁵ Pa or less. The frequency range is a frequency corresponding to the low-speed peeling stress generated when a restoring force or a repulsive force is applied to the double-sided adhesive tape. When the maximum value of the shear storage elastic modulus in the frequency region is 1.0 × ¹⁰⁵ Pa or less, the stress when the double-sided adhesive tape is subjected to the restoring force or the repulsive force is relaxed by the foam base material. Since it is difficult to transmit to the pressure-sensitive adhesive layer, the stress relaxation property and impact resistance of the double-sided pressure-sensitive adhesive tape can be improved.
The shear storage elastic modulus is in the range of -60 ° C to 250 ° C with a temperature rise rate of 5 ° C / min using a dynamic viscoelasticity measuring device (for example, DVA-200 manufactured by IT Measurement Co., Ltd.). Can be measured. When measuring the shear storage elastic modulus, an adhesive is applied to both sides of the base material in order to prevent the sample from being displaced during the measurement. Such an adhesive is not particularly limited, but the thickness of the adhesive applied to both sides of the substrate is adjusted to be 15% or less of the thickness of the substrate, and the measurement is performed. By setting the thickness of the pressure-sensitive adhesive to 15% or less of the thickness of the base material, the influence of the pressure-sensitive adhesive can be eliminated as much as possible and the shear storage elastic modulus of the base material can be measured.

The thickness of the foam base material is not particularly limited, but the preferred lower limit is 0.2 mm and the preferred upper limit is 2.9 mm. By setting the thickness of the foam base material within this range, the double-sided adhesive tape according to one embodiment of the present invention can be suitably used for fixing portable electronic device parts, in-vehicle electronic device parts, and the like. From the viewpoint that the parts and the like can be more preferably used, the more preferable lower limit of the thickness of the foam base material is 0.3 mm, and the more preferable upper limit is 2.5 mm.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer (hereinafter, both of them are also simply referred to as “taste-sensitive adhesive layer”) may have the same composition or may have different compositions. The pressure-sensitive adhesive layer is not particularly limited, and examples thereof include an acrylic pressure-sensitive adhesive layer, a rubber-based pressure-sensitive adhesive layer, a urethane pressure-sensitive adhesive layer, and a silicone-based pressure-sensitive adhesive layer. Among them, an acrylic pressure-sensitive adhesive layer containing an acrylic copolymer because it is relatively stable against light, heat, moisture, etc. and can be adhered to various adherends (adhesive selectivity is low). Is preferable.

The acrylic copolymer constituting the acrylic pressure-sensitive adhesive layer is preferably obtained by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate. The preferable lower limit of the content of the butyl acrylate in the total monomer mixture is 40% by weight, and the preferable upper limit is 80% by weight. By setting the content of the butyl acrylate within this range, both high adhesive strength and tackiness can be achieved at the same time. The preferable lower limit of the content of the 2-ethylhexyl acrylate in the total monomer mixture is 10% by weight, and the preferable upper limit is 40% by weight. By setting the content of the 2-ethylhexyl acrylate within this range, high adhesive strength can be exhibited.

The monomer mixture may contain other copolymerizable monomers other than butyl acrylate and 2-ethylhexyl acrylate, if necessary. Examples of the other copolymerizable monomer include a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms and a (meth) acrylic acid alkyl ester having an alkyl group having 13 to 18 carbon atoms. Examples include functional monomers.
Examples of the (meth) acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acrylic acid. Examples include isopropyl. Examples of the (meth) acrylic acid alkyl ester having 13 to 18 carbon atoms in the alkyl group include tridecylic methacrylic acid and stearyl (meth) acrylic acid. Examples of the functional monomer include (meth) acrylic acid hydroxyalkyl, glycerin dimethacrylate, (meth) glycidyl acrylate, 2-methacryloyloxyethyl isocyanate, (meth) acrylic acid, itaconic acid, maleic anhydride, and crotonic acid. Maleic acid, fumaric acid and the like can be mentioned.

In order to copolymerize the monomer mixture to obtain the acrylic copolymer, the monomer mixture may be subjected to a radical reaction in the presence of a polymerization initiator. As a method of radically reacting the monomer mixture, that is, a polymerization method, a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like.

The weight average molecular weight (Mw) of the acrylic copolymer has a preferable lower limit of 400,000 and a preferable upper limit of 1.5 million. By setting the weight average molecular weight of the acrylic copolymer within this range, high adhesive strength can be exhibited. The more preferable lower limit of the weight average molecular weight is 500,000, and the more preferable upper limit is 1.4 million.
The weight average molecular weight (Mw) is a standard polystyrene-equivalent weight average molecular weight by GPC (Gel Permeation Chromatography).

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic copolymer is preferably 10.0. When Mw / Mn exceeds 10.0, the number of small molecule components increases, the acrylic pressure-sensitive adhesive layer softens at high temperatures, the bulk strength decreases, and the adhesive strength may decrease. A more preferable upper limit of Mw / Mn is 3.0.

The pressure-sensitive adhesive layer may contain a pressure-sensitive adhesive resin.
Examples of the tackifier resin include rosin ester resin, hydrogenated rosin resin, terpene resin, terpene phenol resin, Kumaron inden resin, alicyclic saturated hydrocarbon resin, C5 petroleum resin, and C9 resin. Examples thereof include petroleum resins and C5-C9 copolymerized petroleum resins. These tackifier resins may be used alone or in combination of two or more.

The content of the tackifier resin is not particularly limited, but the preferable lower limit is 10 parts by weight and the preferable upper limit is 60 parts by weight with respect to 100 parts by weight of the resin (for example, acrylic copolymer) which is the main component of the pressure-sensitive adhesive layer. .. If the content of the pressure-sensitive adhesive resin is less than 10 parts by weight, the adhesive strength of the pressure-sensitive adhesive layer may decrease. If the content of the pressure-sensitive adhesive resin exceeds 60 parts by weight, the pressure-sensitive adhesive layer may become hard and the adhesive strength or tackiness may decrease.

The pressure-sensitive adhesive layer has a cross-linked structure formed between the main chains of the resin (for example, the acrylic copolymer, the pressure-sensitive adhesive resin, etc.) constituting the pressure-sensitive adhesive layer by adding a cross-linking agent. Is preferable. The above-mentioned cross-linking agent is not particularly limited, and examples thereof include an isocyanate-based cross-linking agent, an aziridine-based cross-linking agent, an epoxy-based cross-linking agent, and a metal chelate-type cross-linking agent. Of these, isocyanate-based cross-linking agents are preferable. By adding an isocyanate-based cross-linking agent to the pressure-sensitive adhesive layer, the isocyanate group of the isocyanate-based cross-linking agent and the alcohol in the resin constituting the pressure-sensitive adhesive layer (for example, the acrylic copolymer, the pressure-sensitive adhesive resin, etc.) The reaction with the sex hydroxylate loosens the cross-linking of the pressure-sensitive adhesive layer. Therefore, the pressure-sensitive adhesive layer can disperse the peeling stress applied intermittently, and the adhesive strength of the double-sided pressure-sensitive adhesive tape is further improved.
The amount of the cross-linking agent added is preferably 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, based on 100 parts by weight of the resin (for example, the acrylic copolymer) which is the main component of the pressure-sensitive adhesive layer. Is more preferable.

The pressure-sensitive adhesive layer may contain a silane coupling agent for the purpose of improving the pressure-sensitive adhesive strength. The silane coupling agent is not particularly limited, and examples thereof include epoxysilanes, acrylicsilanes, methacrylsilanes, aminosilanes, and isocyanatesilanes.

The pressure-sensitive adhesive layer may contain a coloring material for the purpose of imparting light-shielding properties. The coloring material is not particularly limited, and examples thereof include carbon black, aniline black, and titanium oxide. Of these, carbon black is preferable because it is relatively inexpensive and chemically stable.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit of the thickness of the pressure-sensitive adhesive layer on one side is 0.01 mm, and the preferable upper limit is 0.1 mm. By setting the thickness of the pressure-sensitive adhesive layer within this range, the double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be suitably used for fixing portable electronic device parts, vehicle-mounted electronic device parts, and the like. From the viewpoint that the parts and the like can be more preferably used, the more preferable lower limit of the thickness of the pressure-sensitive adhesive layer is 0.015 mm, and the more preferable upper limit is 0.09 mm.

The double-sided adhesive tape according to an embodiment of the present invention has a first resin between the foam base material and the first pressure-sensitive adhesive layer, and between the foam base material and the second pressure-sensitive adhesive layer. It has a layer and a second resin layer, respectively (hereinafter, both are also simply referred to as a "resin layer"). By having the resin layer, the double-sided adhesive tape according to one embodiment of the present invention adopts the foam base material capable of exhibiting excellent stress relaxation and impact resistance, and at the time of peeling, the foam base material is used. Can be peeled off without leaving a residue on the adherend without cracking, and excellent reworkability can be exhibited on both adhesive surfaces.

The resin layer has a tensile breaking point stress of 4 MPa or more. By using a resin layer having a tensile fracture point stress of 4 MPa or more, excellent reworkability can be exhibited. From the viewpoint of further enhancing the reworkability, the tensile breaking point stress of the resin layer is preferably 5 MPa or more, more preferably 15 MPa or more. The upper limit of the tensile breaking point stress of the resin layer is not particularly limited, but is substantially about 200 MPa.

At least one of the first resin layer and the second resin layer preferably has a tensile fracture point elongation of 200% or more. By using a resin layer having a tensile fracture point elongation of 200% or more, more excellent reworkability can be exhibited. From the viewpoint of further enhancing the reworkability, the tensile fracture point elongation of the resin layer is preferably 300% or more, more preferably 450% or more. The upper limit of the tensile break point elongation of the resin layer is not particularly limited, but is substantially 1500%.

At least one of the first resin layer and the second resin layer preferably has a tensile elastic modulus of 200 MPa or less. By forming at least one of the first resin layer and the second resin layer as a flexible resin layer having a tensile elastic modulus of 200 MPa or less, the flexibility of the entire double-sided adhesive tape is ensured and the double-sided adhesive tape is rolled. It becomes easy to wind up and the handleability is significantly improved.

In the present specification, the tensile breaking point stress, the tensile breaking point elongation and the tensile elastic modulus mean the mechanical properties of the resin layer and can be measured by a method according to JIS K 7161.
Specifically, for example, a test piece is produced by punching the resin layer onto a dumbbell using a punching blade "tensile No. 1 type dumbbell-shaped" manufactured by Polymer Instruments. The obtained test piece is measured at a tensile speed of 100 mm / min using, for example, "Autograph AGS-X" manufactured by Shimadzu Corporation, and the test piece is broken. The tensile breaking stress is calculated from the breaking strength per unit area when the test piece breaks. From the elongation when the test piece breaks, the tensile break point elongation is calculated by "(distance between grips at break / distance between initial grips) x 100". The tensile modulus is calculated from the slope of the tensile strength between the strains of 1 to 3%.

The resin constituting the resin layer is not particularly limited, and for example, polyester resin such as polyethylene terephthalate, acrylic resin, polyethylene resin, polypropylene resin, polyvinyl chloride, epoxy resin, silicone resin, phenol resin, polyimide, etc. Examples thereof include polyester and polycarbonate. Of these, acrylic resins, polyethylene resins, polypropylene resins, and polyester resins are preferable because they are excellent in flexibility. Among the polyester-based resins, polyethylene terephthalate is preferable.

The resin constituting at least one of the first resin layer and the second resin layer is preferably made of a thermoplastic elastomer from the viewpoint of further enhancing stress relaxation property, impact resistance and reworkability.
The thermoplastic elastomer is a styrene-based (co) polymer, an olefin-based (co) polymer, a vinyl chloride-based (co) polymer, a polyether ester-based triblock-based (co) polymer, and a polyester-based (co) heavy weight. It may be a coalescence, a urethane-based (co) polymer, an amide-based (co) polymer, or an acrylic (co) polymer. Above all, it is possible to exhibit strength, elongation, flexibility, and self-adhesiveness as an elastic body, and it is possible to further improve the adhesion between the resin layer and the foam base material while exhibiting excellent reworkability. From the viewpoint of being able to do so, it is preferable that the thermoplastic elastomer is an acrylic (co) polymer, a styrene (co) polymer, or an olefin (co) polymer. Further, an acrylic (co) polymer or a styrene (co) polymer is more preferable, and an acrylic (co) polymer is further preferable.
The proportion of the thermoplastic elastomer in the resin constituting at least one of the first resin layer and the second resin layer is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, particularly. It is preferably 95% by weight or more, and may be 100% by weight.

In a preferred embodiment of the present invention, the thermoplastic elastomer is preferably made of a block copolymer having a hard segment and a soft segment from the viewpoint of further enhancing stress relaxation property, impact resistance and reworkability, for example. , The above-mentioned thermoplastic elastomer is a block copolymer having a hard segment and a soft segment.
In a more preferred embodiment of the present invention, the thermoplastic elastomer is more preferably composed of a triblock copolymer having a hard segment and a soft segment. That is, the resin constituting at least one of the first resin layer and the second resin layer is made of a triblock copolymer having a hard segment and a soft segment, or a triblock having a hard segment and a soft segment. It is more preferably a copolymer. By using such a triblock copolymer, it is possible to exhibit strength, elongation, flexibility, and self-adhesiveness as an elastic body, and while exhibiting excellent reworkability, a resin layer and a foam base material can be exhibited. Adhesion with and can be further improved.

Examples of the triblock copolymer include an acrylic triblock copolymer, a styrene triblock copolymer, a polyether ester triblock copolymer, a urethane copolymer, and a vinyl chloride copolymer. , Amid-based copolymers and the like.

The proportion of the hard segment in the block copolymer or the triblock copolymer is preferably 10% by weight or more and 70% by weight or less, and more preferably 12% by weight or more and 65% by weight or less. It is more preferably 14% by weight or more and 60% by weight or less, and particularly preferably 55% by weight or less. By setting the ratio of the hard segment within this range, the adhesion of the resin layer to the foam base material, particularly the polyurethane foam or the foam base material made of the polyolefin foam, is improved.
Among them, the ratio of the hard segment is 10% by weight or more and 60% by weight or less from the viewpoint of improving the adhesion of the resin layer to the foam base material, particularly the polyurethane foam or the foam base material made of the polyolefin foam. The acrylic triblock copolymer is more preferable. If an acrylic triblock copolymer having excellent adhesion is used, it is not necessary to use an adhesive or the like to adhere the resin layer to the foam base material, and the thickness of the obtained double-sided adhesive tape can be reduced. can.

Further, the thermoplastic elastomer is composed of a triblock copolymer and a diblock copolymer (with the triblock copolymer and the diblock copolymer) from the viewpoint of further enhancing stress relaxation property, impact resistance and reworkability. (Consists of a mixture of) is also preferred.
In a preferred embodiment of the present invention, the proportion of the triblock copolymer in the thermoplastic elastomer is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 90% by weight or more. It is 95% by weight or more, and may be 100% by weight.

The components constituting the hard segment of the acrylic triblock copolymer are not particularly limited, but are methyl methacrylate, ethyl methacrylate, -n-butyl methacrylate, -2-ethylhexyl methacrylate, lauryl methacrylate, and methacrylic acid. Examples thereof include alkyl and tridecyl methacrylate.
The components constituting the soft segment of the acrylic triblock copolymer are not particularly limited, and examples thereof include butyl n-butyl acrylate, methyl acrylate, ethyl acrylate, and -2-ethylhexyl acrylate.
Among them, an acrylic triblock copolymer having a hard segment derived from methyl methacrylate and a soft segment derived from butyl n-acrylate is preferable.

When the acrylic triblock copolymer has a hard segment derived from methyl methacrylate and a soft segment derived from butyl n-acrylate, the acrylic triblock copolymer is contained in the triblock copolymer. The preferred lower limit for the proportion of hard segments derived from methyl methacrylate is 22% by weight. The preferred upper limit is 50% by weight. Further, the more preferable lower limit of the ratio of the hard segment derived from methyl methacrylate is 24% by weight, and the more preferable upper limit is 48% by weight. When the ratio of the hard segment derived from the methyl methacrylate is within this range, particularly excellent adhesion to the foam base material can be exhibited, and the float floats between the foam base material and the resin layer. Etc. can be prevented from occurring. In addition, it can exhibit excellent heat resistance and heat shrinkage, and even when heat-treated at 100 to 200 ° C. for 10 to 30 minutes, it may melt or wrinkle. do not have. Furthermore, when an attempt is made to unfold after forming a roll, it does not become impossible to unfold due to blocking.

When the acrylic triblock copolymer is an acrylic triblock copolymer having a hard segment derived from methyl methacrylate and a soft segment derived from n-butyl n-acrylate, the weight of the triblock copolymer The average molecular weight is preferably 30,000 or more. When the weight average molecular weight of the triblock copolymer is 30,000 or more, it is possible to exhibit particularly excellent adhesion to the foam substrate and to exhibit reworkability of the double-sided adhesive tape. can. It is more preferable that the weight average molecular weight of the triblock copolymer is 50,000 or more. The upper limit of the weight average molecular weight of the triblock copolymer is not particularly limited, but is about 200,000 in consideration of handleability and the like.

The resin layer may be colored. By coloring the resin layer, it is possible to impart light-shielding properties to the double-sided adhesive tape.
The method of coloring the resin layer is not particularly limited, and for example, a method of kneading particles such as carbon black or titanium oxide or fine bubbles into the resin constituting the resin layer, or applying ink to the surface of the resin layer. The method and the like can be mentioned.

The resin layer may contain conventionally known additives such as an ultraviolet absorber, an antioxidant, an organic filler, and an inorganic filler, if necessary. When the resin constituting at least one of the first resin layer and the second resin layer is made of a thermoplastic elastomer, the resin may contain a resin other than the thermoplastic elastomer.

The thickness of the resin layer is not particularly limited, but a preferable lower limit is 5 μm and a preferable upper limit is 100 μm. By setting the thickness of the resin layer within this range, the double-sided adhesive tape according to one embodiment of the present invention can exhibit more excellent reworkability. From the viewpoint of further enhancing the reworkability, the more preferable lower limit of the thickness of the resin layer is 10 μm, and the more preferable upper limit is 70 μm.

The double-sided adhesive tape according to one embodiment of the present invention may have a layer other than the foam base material, the pressure-sensitive adhesive layer and the resin layer, if necessary.

The thickness of the double-sided adhesive tape according to one embodiment of the present invention is not particularly limited, but the preferred lower limit is 0.3 mm and the preferred upper limit is 3 mm. By setting the thickness of the double-sided adhesive tape according to one embodiment of the present invention within this range, it is possible to prevent the double-sided adhesive tape from peeling off because it cannot withstand the restoring force and the repulsive force, and while realizing sufficient adhesion and fixing. It can demonstrate excellent reworkability. From the viewpoint of suppressing peeling of the double-sided tape and further improving the reworkability, the more preferable lower limit of the thickness of the double-sided adhesive tape according to one embodiment of the present invention is 0.4 mm, and the more preferable upper limit is 2.8 mm.

Examples of the method for manufacturing the double-sided adhesive tape according to one embodiment of the present invention include the following methods. First, a laminate of the foam base material and the first resin layer is manufactured, a second resin layer is laminated on the laminate, and the first resin layer / foam base material / second resin layer is used. To form a laminated body.
Here, in order to laminate the resin layer and the foam base material, it is preferable that the resin layer has self-adhesiveness (tackiness). Further, the adhesion can be improved by crimping the resin layer and the foam base material with a heated laminator. Further, the adhesion can be further improved by inserting the resin layer in the process of foaming the base material to obtain the foam base material. Further, the adhesion between the resin layer and the foam base material can be improved by subjecting the surface of the resin sheet used as the resin layer or the foam base material to a surface treatment (for example, plasma treatment, corona treatment, etc.). Can be done. Further, when the resin layer does not have self-adhesiveness, an adhesive layer may be provided between the foam base material and the resin layer and laminated. By modifying the polymer chain of the resin layer with a hydroxyl group or an acid group as a reaction point, the adhesion between the resin layer and the foam base material can be improved.
Next, a pressure-sensitive adhesive solution forming the pressure-sensitive adhesive layer is prepared, the pressure-sensitive adhesive solution is applied to the release-treated surface of the release film, and the solvent in the solution is completely dried and removed to remove the first pressure-sensitive adhesive. Form a layer. The first pressure-sensitive adhesive layer is placed on the surface of the laminate composed of the first resin layer / foam base material / second resin layer on the first resin layer side, and the first pressure-sensitive adhesive layer is first. Overlay in a state facing the resin layer side. On the other hand, a release film different from the above-mentioned release film is prepared, an adhesive solution is applied to the release-treated surface of the release film, and the solvent in the solution is completely dried and removed to remove the release film. A laminated film having a second pressure-sensitive adhesive layer formed on the surface of the film is produced. The obtained laminated film is placed on the surface of the laminated body composed of the first resin layer / foam base material / second resin layer on the second resin layer side, and the second pressure-sensitive adhesive layer is a second resin layer. By superimposing the layers so as to face each other, a laminate composed of a first pressure-sensitive adhesive layer / a first resin layer / a foam base material / a second resin layer / a second pressure-sensitive adhesive layer is obtained. Then, by pressurizing the obtained laminate with a rubber roller or the like, it has a first pressure-sensitive adhesive layer / first resin layer / foam base material / second resin layer / second pressure-sensitive adhesive layer. Moreover, it is possible to obtain a double-sided adhesive tape in which the surfaces of both adhesive layers are covered with a release film. Further, when winding on a roll, the release film in contact with the second pressure-sensitive adhesive layer is peeled off, and the second pressure-sensitive adhesive layer can be wound inward. At this time, the release film in contact with the first pressure-sensitive adhesive layer needs to be subjected to double-sided release treatment.

The use of the double-sided adhesive tape according to one embodiment of the present invention is not particularly limited, and is used for fixing, for example, portable electronic device parts, in-vehicle electronic device parts, and the like. The shape of the double-sided adhesive tape according to one embodiment of the present invention in these uses is not particularly limited, and examples thereof include a rectangular shape, a frame shape, a circular shape, an elliptical shape, and a donut shape.

The double-sided adhesive tape according to one embodiment of the present invention is excellent in adhesive reliability in a state where peeling stress at a low speed such as a restoring force or a repulsive force is applied, and therefore is attached to a step, a corner, a non-flat portion, or the like. It is preferably attached or used to fix the component in a deformed state. On the other hand, since it is excellent in reworkability, it can be suitably used for temporary fixing. Further, even if it is desired to peel off after bonding for some reason, the foam base material does not crack at the time of peeling and the residue does not remain on the adherend.

Articles to which the double-sided adhesive tape according to one embodiment of the present invention is used include, for example, flat panel displays used in TVs, monitors, portable electronic devices, camera modules of portable electronic devices, internal members of portable electronic devices, vehicles, and the like. Examples include interiors and exteriors of home appliances (for example, TVs, air conditioners, refrigerators, etc.). Examples of the adherend of the double-sided adhesive tape according to one embodiment of the present invention include side panels, back panels, various name plates, decorative films, decorative films, etc. of portable electronic devices.

According to the present invention, it is possible to provide a double-sided adhesive tape having excellent stress relaxation and impact resistance and excellent reworkability on both adhesive surfaces.

It is a schematic diagram which shows an example of the double-sided adhesive tape which concerns on one Embodiment of this invention.

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.

(Example 1)
(1) Preparation of First Resin Layer As the first resin layer, a polyethylene terephthalate (PET) sheet (manufactured by Toray Industries, Inc., X30) having a thickness of 50 μm was prepared. When measured by a method according to JIS K 7161, the PET sheet had a tensile fracture point stress of 180 MPa, a tensile fracture point elongation of 138%, and a tensile elastic modulus of 4360 MPa.

(2) Production of Polyurethane (PU) Foam Base Material Polyol (polyether polyol, weight average molecular weight 6000, number of hydroxyl groups 3, hydroxyl value 48 mgKOH / g) 100 parts by weight and amine catalyst (Dowco LV33, manufactured by Sankyo Air Products Co., Ltd.) 0.7 part by weight and 1 part by weight of a foam stabilizer (SZ5740M, manufactured by Toray Dow Corning) were added and stirred. Polyisocyanate (Cosmonate TM-20, manufactured by Mitsui Chemicals, Inc.) was adjusted and added therein so as to have an isocyanate index of 80. Then, it was mixed and stirred with nitrogen gas so as to be 0.2 g / cm ³ , and a solution containing fine bubbles was obtained. The solution is applied to a predetermined thickness using an applicator on a polyethylene terephthalate (PET) sheet (manufactured by Toray Industries, Inc., X30) having a thickness of 50 μm, which is a first resin layer, and the foam raw material is reacted to have a thickness of 450 μm. A laminate composed of a polyurethane (PU) foam base material and a first resin layer was obtained.
The density of the obtained PU foam base material was measured using an electronic hydrometer (“ED120T” manufactured by Mirage Co., Ltd.) in accordance with JISK-6767, and as a result, it was 0.3 g / cm ³ . Further, the 25% compressive strength of the obtained PU foam base material was determined by measuring in accordance with JIS K 6254, and as a result, it was 15 kPa.

(3) Preparation of Second Resin Layer As the second resin layer, a sheet (LA2250 manufactured by Kuraray Co., Ltd.) made of an acrylic triblock copolymer a (acrylic TPE-a) having a thickness of 50 μm was prepared.
The acrylic TPE-a has a ratio of hard segments derived from polymethyl methacrylate resin of 30% by weight, a ratio of soft segments derived from butyl polyacrylate resin of 70% by weight, and a weight average molecular weight of 59000.
As a result of measurement by a method according to JIS K 7161, the sheet made of acrylic TPE-a had a tensile fracture point stress of 8.0 MPa, a tensile fracture point elongation of 493%, and a tensile elastic modulus of 10.1 MPa.

(4) Preparation of Adhesive Solution 52 parts by weight of ethyl acetate was placed in a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after nitrogen substitution, the reactor was heated to start reflux. Thirty minutes after the ethyl acetate boiled, 0.08 part by weight of azobisisobutyronitrile was added as a polymerization initiator. A monomer mixture consisting of 70 parts by weight of butyl acrylate, 27 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate was added dropwise thereto evenly and gradually over 1 hour and 30 minutes. It was reacted. Thirty minutes after the completion of the dropping, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was further carried out for 5 hours. Ethyl acetate was added into the reactor and cooled while diluting to obtain a solid content of 40% by weight. A solution of acrylic copolymer was obtained.
The weight average molecular weight of the obtained acrylic copolymer was 710,000 as a result of measuring the weight average molecular weight by the GPC method using "2690 Separations Model" manufactured by Water Co., Ltd. as a column. The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) was 5.5.
With respect to 100 parts by weight of the solid content of the obtained acrylic copolymer, 15 parts by weight of the polymerized rosin ester having a softening point of 150 ° C., 10 parts by weight of terpene phenol having a softening point of 145 ° C., and 10 parts by weight of a rosin ester having a softening point of 70 ° C. Was added. Further, 30 parts by weight of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) and 3.0 parts by weight of an isocyanate-based cross-linking agent (trade name "Coronate L45" manufactured by Nippon Polyurethane Industry Co., Ltd.) are added and stirred to obtain a pressure-sensitive adhesive solution. rice field.

(5) Production of Double-sided Adhesive Tape From the acrylic triblock copolymer a as the second resin layer on the PU foam base material side of the laminate composed of the obtained PU foam base material and the first resin layer. Sheets were laminated and heat-laminated at 80 ° C. to form a laminate composed of a first resin layer / foam base material / second resin layer.
The above pressure-sensitive adhesive solution is applied to the release-treated surface of a release liner made of polyethylene (PE) / high-quality paper / polyethylene (PE) having a thickness of 100 μm and dried at 100 ° C. for 5 minutes. A first pressure-sensitive adhesive layer having a thickness of 50 μm was formed.

On the other hand, the above pressure-sensitive adhesive solution is applied to the release-treated surface of a release liner made of polyethylene (PE) / high-quality paper / polyethylene (PE) having a thickness of 100 μm and dried at 100 ° C. for 5 minutes. A second pressure-sensitive adhesive layer having a thickness of 50 μm was formed.
The release liner on which the second pressure-sensitive adhesive layer was formed was placed on the surface of the laminate composed of the first resin layer / foam base material / second resin layer on the surface on the second resin layer side. From the first pressure-sensitive adhesive layer / first resin layer / foam base material / second resin layer / second pressure-sensitive adhesive layer by superimposing the pressure-sensitive adhesive layer so as to face the second resin layer side. Was obtained. Then, by pressurizing the obtained laminate with a rubber roller, it has a first pressure-sensitive adhesive layer / first resin layer / foam base material / second resin layer / second pressure-sensitive adhesive layer. , A double-sided adhesive tape was obtained in which the surface of each adhesive layer was covered with a release liner.

(Example 2)
As the second resin layer, a double-sided adhesive tape was applied in the same manner as in Example 1 except that a sheet (LA2140e manufactured by Kuraray Co., Ltd.) made of an acrylic triblock copolymer b (acrylic TPE-b) having a thickness of 50 μm was used. Manufactured.
The acrylic TPE-b has a ratio of hard segments derived from polymethyl methacrylate resin of 21% by weight, a ratio of soft segments derived from butyl polyacrylate resin of 79% by weight, and a weight average molecular weight of 73000.
As a result of measurement by a method according to JIS K 7161, the sheet made of the acrylic TPE-b had a tensile fracture point stress of 5.0 MPa, a tensile fracture point elongation of 602%, and a tensile elastic modulus of 1.0 MPa.

(Example 3)
As the second resin layer, a double-sided adhesive tape was applied in the same manner as in Example 1 except that a sheet (LA2330 manufactured by Kuraray Co., Ltd.) made of an acrylic triblock copolymer c (acrylic TPE-c) having a thickness of 50 μm was used. Manufactured.
The acrylic TPE-c has a ratio of hard segments derived from polymethyl methacrylate resin of 23% by weight, a ratio of soft segments derived from butyl polyacrylate resin of 77% by weight, and a weight average molecular weight of 112000.
As a result of measurement by a method according to JIS K 7161, the sheet made of acrylic TPE-c had a tensile fracture point stress of 4.6 MPa, a tensile fracture point elongation of 550%, and a tensile elastic modulus of 0.6 MPa.

(Example 4)
As the second resin layer, a double-sided adhesive tape was applied in the same manner as in Example 1 except that a sheet (LA4285 manufactured by Kuraray Co., Ltd.) made of an acrylic triblock copolymer d (acrylic TPE-d) having a thickness of 50 μm was used. Manufactured.
The acrylic TPE-d has a ratio of hard segments derived from polymethyl methacrylate resin of 55% by weight, a ratio of soft segments derived from butyl polyacrylate resin of 45% by weight, and a weight average molecular weight of 60,000.
When measured by a method according to JIS K 7161, the acrylic TPE-d sheet had a tensile fracture point stress of 18.1 MPa, a tensile fracture point elongation of 232%, and a tensile elastic modulus of 275.1 MPa.

(Example 5)
As the second resin layer, a double-sided adhesive tape was applied in the same manner as in Example 1 except that a sheet (LA2270 manufactured by Kuraray Co., Ltd.) made of an acrylic triblock copolymer e (acrylic TPE-e) having a thickness of 50 μm was used. Manufactured.
The acrylic TPE-e has a hard segment ratio derived from the polymethyl methacrylate resin of 40% by weight, a soft segment ratio derived from the butyl polyacrylate resin of 60% by weight, and a weight average molecular weight of 60,000.
When measured by a method according to JIS K 7161, the acrylic TPE-e sheet had a tensile fracture point stress of 11.4 MPa, a tensile fracture point elongation of 434%, and a tensile elastic modulus of 51.8 MPa.

(Example 6)
As the second resin layer, an acrylic triblock copolymer e (acrylic TPE-e) (manufactured by Kuraray, LA2270) having a thickness of 50 μm and an acrylic diblock copolymer f (acrylic TPE-f) (manufactured by Kuraray). , LA1114), a double-sided adhesive tape was produced in the same manner as in Example 1 except that a sheet having a weight ratio of 85/15 was used.
The acrylic TPE-e has a hard segment ratio derived from the polymethyl methacrylate resin of 40% by weight, a soft segment ratio derived from the butyl polyacrylate resin of 60% by weight, and a weight average molecular weight of 60,000.
When measured by a method according to JIS K 7161, the sheet composed of the acrylic TPE-e and the acrylic TPE-f had a tensile fracture point stress of 4.3 MPa, a tensile fracture point elongation of 660%, and a tensile elastic modulus of 0.8 MPa. Met.

(Example 7)
A double-sided adhesive tape was produced in the same manner as in Example 1 except that a sheet made of a styrene / acrylic triblock copolymer (styrene / acrylic TPE) having a thickness of 50 μm was used as the second resin layer.
The styrene / acrylic TPE has a polystyrene resin-derived hard segment ratio of 17% by weight, a polyacrylic acid butyl resin-derived soft segment ratio of 83% by weight, and a weight average molecular weight of 240000.
As a result of measurement by a method according to JIS K 7161, the sheet made of styrene / acrylic TPE had a tensile fracture point stress of 7.6 MPa, a tensile fracture point elongation of 650%, and a tensile elastic modulus of 1.9 MPa.

(Example 8)
As the second resin layer, double-sided adhesiveness is carried out in the same manner as in Example 1 except that a sheet (made by Nippon Zeon Corporation, # 3620) made of a styrene-based triblock copolymer a (styrene TPE-a) having a thickness of 50 μm is used. Manufactured the tape.
The styrene TPE-a has a styrene-derived hard segment ratio of 14% by weight and an isoprene-derived soft segment ratio of 86% by weight. It also contains 12% of the diblock component of the same composition in terms of GPC area ratio.
When measured by a method according to JIS K 7161, the sheet made of styrene TPE-a had a tensile fracture point stress of 24.0 MPa, a tensile fracture point elongation of 1200%, and a tensile elastic modulus of 40.0 MPa.

(Example 9)
As the second resin layer, double-sided adhesiveness is carried out in the same manner as in Example 1 except that a sheet (made by Nippon Zeon Corporation, # 3421) made of a styrene-based triblock copolymer b (styrene TPE-b) having a thickness of 50 μm is used. Manufactured the tape.
The styrene TPE-b has a styrene-derived hard segment ratio of 14% by weight and an isoprene-derived soft segment ratio of 86% by weight. It also contains 26% of the diblock component of the same composition in terms of GPC area ratio.
When measured by a method according to JIS K 7161, the sheet made of styrene TPE-b had a tensile fracture point stress of 19.0 MPa, a tensile fracture point elongation of 1300%, and a tensile elastic modulus of 38.0 MPa.

(Example 10)
Same as Example 1 except that a sheet (manufactured by Toray DuPont Co., Ltd., # 5557) made of a polyether ester block copolymer a (polyether ester TPE-a) having a thickness of 50 μm was used as the second resin layer. The double-sided adhesive tape was manufactured.
The polyether ester TPE-a has a hard segment derived from PBT and a soft segment derived from polyether.
When measured by a method according to JIS K 7161, the sheet made of the polyether ester TPE-a had a tensile fracture point stress of 31.4 MPa, a tensile fracture point elongation of 390%, and a tensile elastic modulus of 137.0 MPa. ..

(Example 11)
Same as Example 1 except that a sheet (manufactured by Toray DuPont, # 7247) made of a polyether ester block copolymer b (polyether ester TPE-b) having a thickness of 50 μm was used as the second resin layer. The double-sided adhesive tape was manufactured.
The polyether ester TPE-b has a hard segment derived from PBT and a soft segment derived from polyether.
When measured by a method according to JIS K 7161, the sheet made of the polyether ester TPE-b had a tensile fracture point stress of 36.3 MPa, a tensile fracture point elongation of 260%, and a tensile elastic modulus of 422.0 MPa. ..

(Example 12)
A double-sided adhesive tape was produced in the same manner as in Example 1 except that a sheet (1198ATR manufactured by BASF) made of a urethane-based block copolymer (urethane TPE) having a thickness of 60 μm was used as the second resin layer.
When measured by a method according to JIS K 7161, the urethane TPE sheet had a tensile fracture point stress of 57.1 MPa, a tensile fracture point elongation of 406%, and a tensile elastic modulus of 108.0 MPa.

(Example 13)
As the second resin layer, a sheet made of biaxially stretched polypropylene (OPP) having a thickness of 60 μm (manufactured by Toyobo Co., Ltd., # 60) is used, and an adhesive layer is used for laminating the second resin layer and the foam base material. A double-sided adhesive tape was produced in the same manner as in Example 1 except that the tapes were laminated via the same.
When measured by a method according to JIS K 7161, the OPP sheet had a tensile fracture point stress of 140.0 MPa, a tensile fracture point elongation of 210%, and a tensile elastic modulus of 2100.0 MPa.

(Example 14)
As the second resin layer, a sheet made of polyethylene terephthalate (PET) having a thickness of 25 μm (manufactured by Toyobo Co., Ltd., # 25) is used, and the second resin layer and the foam base material are laminated via an adhesive layer. A double-sided adhesive tape was produced in the same manner as in Example 1 except that the tapes were laminated.
When measured by a method according to JIS K 7161, the PET sheet had a tensile fracture point stress of 177.0 MPa, a tensile fracture point elongation of 132%, and a tensile elastic modulus of 2376.0 MPa.

(Comparative Example 1)
A pulp non-woven fabric sheet (manufactured by Ritsuto Trading Co., Ltd., SPC) having a thickness of 50 μm was used as the second resin layer, except that the second resin layer and the foam base material were laminated via an adhesive layer. Manufactured a double-sided adhesive tape in the same manner as in Example 1.
As a result of measurement by a method according to JIS K 7161, the pulp nonwoven fabric sheet had a tensile fracture point stress of 3.7 MPa, a tensile fracture point elongation of 102%, and a tensile elastic modulus of 160.0 MPa.

(Comparative Example 2)
A double-sided adhesive tape was produced in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive having a thickness of 50 μm was used as the second resin layer.
As a result of measurement by a method according to JIS K 7161, the layer made of the acrylic pressure-sensitive adhesive had a tensile fracture point stress of 0.5 MPa, a tensile fracture point elongation of 825%, and a tensile elastic modulus of 0.2 MPa.
The acrylic adhesive was prepared by the following method.
After 52 parts by weight of ethyl acetate was placed in a reactor equipped with a thermometer, a stirrer and a cooling tube and replaced with nitrogen, the reactor was heated to start reflux. Thirty minutes after the ethyl acetate boiled, 0.08 part by weight of azobisisobutyronitrile was added as a polymerization initiator. Here, a monomer mixture (60 parts by weight of butyl acrylate (BA), 36.9 parts by weight of 2-ethylhexyl acrylate (2EHA), 3 parts by weight of acrylic acid (AAc), and 2-hydroxyethyl acrylate (2HEA) ) 0.1 part by weight) was added dropwise evenly and gradually over 1 hour and 30 minutes to react. 30 minutes after the completion of the dropping, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was further carried out for 5 hours. Ethyl acetate was added to the reactor and cooled while diluting to cool the solution containing an acrylic copolymer. Got
Ethyl acetate was added to 100 parts by weight of the non-volatile content of the obtained acrylic copolymer-containing solution and stirred to add a total of 30 parts by weight of the tackifier resin (10 parts of hydrogenated rosin-based resin, 10 parts of rosin ester-based resin, (10 parts of terpene phenol resin) was added and stirred to obtain a pressure-sensitive adhesive having a non-volatile content of 30% by weight.

(Comparative Example 3)
As the second resin layer, a double-sided adhesive tape was applied in the same manner as in Example 1 except that a sheet made of an acrylic diblock copolymer f (acrylic TPE-f) (LA1114 manufactured by Kuraray Co., Ltd.) having a thickness of 50 μm was used. Manufactured.
When measured by a method according to JIS K 7161, the acrylic TPE-f sheet had a tensile fracture point stress of 1.2 MPa, a tensile fracture point elongation of 990%, and a tensile elastic modulus of 0.3 MPa.

(evaluation)
The double-sided adhesive tapes obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

(1) Evaluation of flexibility The obtained double-sided adhesive tape (release liner / first adhesive layer / first resin layer / foam base material / second resin layer / second adhesive layer) is applied. A roll-shaped body was obtained by winding it around a paper core having a diameter of 3 inches so that the second adhesive layer side was on the inside.
The side surface and surface layer of the obtained roll-shaped body were visually observed. Further, after the double-sided adhesive tape was pulled out from the roll-shaped body, it was visually observed from the second pressure-sensitive adhesive layer side and evaluated according to the following criteria.
◯: No wrinkles or creases were found in all the confirmed parts.
Δ: Wrinkles and creases were observed in some of the confirmed parts.
X: Wrinkles and creases were observed in all the confirmed parts.

(2) Evaluation of Reworkability The obtained double-sided adhesive tape was cut into a size of 5 mm in width × 100 mm in length and 10 mm in width × 100 mm in length, respectively, and a 5 mm width sample and a 10 mm width sample were prepared.
The release liner on the first pressure-sensitive adhesive layer side of each obtained sample is peeled off, the first pressure-sensitive adhesive layer side is bonded to a glass plate (width 50 mm, length 125 mm) having a thickness of 2 mm, and the first pressure-sensitive adhesive layer side is bonded onto a double-sided adhesive tape. A 2 kg rubber roller was reciprocated once at a speed of 300 mm / min, and then left in an environment of 23 ° C. and a relative humidity of 50% for 24 hours. Next, the layers of the foam base material were torn apart, the second pressure-sensitive adhesive layer, the second resin layer, and a part of the foam base material were removed from the double-sided adhesive tape, and then the remaining portion of the double-sided adhesive tape was removed. Was pulled at a speed of 300 mm / min in an angle direction of 30 ° from the horizontal direction, and the remaining portion of the double-sided adhesive tape was peeled off from the glass plate. The reworkability of the first pressure-sensitive adhesive layer was evaluated according to the following criteria. The same evaluation was performed on the second pressure-sensitive adhesive layer side.
◯: The remaining part of the double-sided adhesive tape could be removed.
Δ: Although a part of the double-sided adhesive tape was broken during peeling, it could be removed.
X: The remaining part of the double-sided adhesive tape could not be removed.

According to the present invention, it is possible to provide a double-sided adhesive tape having excellent stress relaxation and impact resistance and excellent reworkability on both adhesive surfaces.

1 Double-sided adhesive tape 2 Foam base material 31 First adhesive layer 32 Second adhesive layer 41 First resin layer 42 Second resin layer

Claims (10)

A double-sided adhesive tape having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on both sides of a foam base material and the foam base material, respectively.
A first resin layer having a tensile breaking point stress of 4 MPa or more between the foam base material and the first pressure-sensitive adhesive layer, and between the foam base material and the second pressure-sensitive adhesive layer, and Each has a second resin layer
The resin constituting the first resin layer is a polyester resin, and the resin is a polyester resin.
The second resin layer is made of a thermoplastic elastomer and is made of a thermoplastic elastomer.
The thermoplastic elastomer is composed of a block copolymer having a hard segment and a soft segment.
Double-sided adhesive tape featuring that. The double-sided adhesive tape according to claim 1, wherein the second resin layer has a tensile breaking point elongation of 200% or more. The double-sided adhesive tape according to claim 1 or 2, wherein the second resin layer has a tensile elastic modulus of 200 MPa or less. The double-sided adhesive tape according to any one of claims 1 to 3 , wherein the second resin layer is made of an acrylic copolymer. The double-sided adhesive tape according to any one of claims 1 to 4, wherein the second resin layer is made of a triblock copolymer. The double-sided adhesive tape according to claim 5 , wherein the second resin layer is made of a mixture of a triblock copolymer and a diblock copolymer. The double-sided adhesive tape according to claim 6 , wherein the second resin layer has a proportion of the triblock copolymer of 70% by weight or more. The double-sided adhesive tape according to any one of claims 1 to 7 , wherein the ratio of the hard segment in the block copolymer is 10% by weight or more and 70% by weight or less. The triblock copolymer is an acrylic triblock copolymer, and the acrylic triblock copolymer has a hard segment derived from methyl methacrylate and a soft segment derived from butyl n-acrylate. The ratio of the hard segment derived from the methyl methacrylate in the acrylic triblock copolymer is 22% by weight or more and 50% by weight or less, and the weight average molecular weight of the acrylic triblock copolymer is The double-sided adhesive tape according to any one of claims 5 to 8 , wherein the amount is 30,000 or more. The double-sided adhesive tape according to any one of claims 1 to 9 , wherein the foam base material is made of a polyurethane foam or a polyolefin foam.

Images