JP6269034B2 - Double-sided adhesive tape - Google Patents

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape that can be used for fixing various components constituting an electronic device or the like.

  The double-sided adhesive tape is used for fixing components constituting various electronic devices. For example, in small electronic devices such as mobile phones, cameras, and personal computers, double-sided adhesive is used to fix rigid parts together, such as fixing the protective panel and housing of the image display unit, and fixing external parts, batteries, and various component modules. Tape is being used.

  As a double-sided pressure-sensitive adhesive tape that can be used for fixing components constituting a small electronic device or the like, for example, a double-sided pressure-sensitive adhesive tape using a flexible foam as a base material is known (see Patent Documents 1 and 2).

  When fixing an adherend such as two or more parts using the double-sided adhesive tape, when the material of the adherend is different, or when the adhesive force of each adhesive layer constituting the double-sided adhesive tape is different, etc. The direction in which the double-sided pressure-sensitive adhesive tape is affixed may be determined. Specifically, parts that are relatively expensive and used repeatedly are pasted on the surface of a pressure-sensitive adhesive layer that has a structure in which the adhesive residue is relatively difficult to remove from the double-sided adhesive tape, or the adhesive residue is easily removed. For example, a case where it is determined that a part of the double-sided pressure-sensitive adhesive tape is stuck on the surface of the pressure-sensitive adhesive layer where adhesive residue may be generated may be mentioned.

  However, since it cannot be determined at a glance which of the adhesive layers constituting the front and back of the double-sided adhesive tape is the desired adhesive layer, the adherend is fixed using the double-sided adhesive tape. An error in the direction of applying the double-sided pressure-sensitive adhesive tape may occur in the work scene, which may reduce the yield of the finally obtained bonded article.

  By the way, since the said small electronic device has many opportunities to be carried and used, there exists a possibility that a strong impact will be given to a small electronic device by dropping it.

  The conventional double-sided pressure-sensitive adhesive tape may be peeled off by the impact, and as a result, the component constituting the small electronic device may be lost. Therefore, the double-sided pressure-sensitive adhesive tape is required to have a level of impact resistance that can withstand the impact of the drop.

  Further, for small electronic devices whose functions are increasing, expensive parts such as a thin plate-shaped rigid body such as a protection panel of an image display unit, an image display module, and a thin battery are used. For this reason, the adhesive tape is required to have a level of disassembly that allows the components to be separated from the electronic device relatively easily and efficiently when a failure of the electronic device occurs.

  Further, when the component is separated from the main body of the electronic device or the like, the adhesive of the double-sided adhesive tape may remain on the component or the main body. The parts in which the glue or the like remains may cause a problem when reused. Therefore, the double-sided pressure-sensitive adhesive tape is required to have a characteristic that can easily remove adhesive residue even when it is peeled off.

JP 2010-155969 A JP 2010-260880 A

  The problem to be solved by the present invention is to provide a double-sided pressure-sensitive adhesive tape capable of identifying the difference between the pressure-sensitive adhesive layers constituting the front and back of the double-sided pressure-sensitive adhesive tape.

  In addition, the second problem to be solved by the present invention is that it has suitable impact resistance and can be suitably disassembled when a certain force is applied, such as glue remaining on the surface of the adherend. It is an object of the present invention to provide a double-sided pressure-sensitive adhesive tape that can easily peel off and remove the residue, and that can identify the difference between the pressure-sensitive adhesive layers constituting the front and back of the double-sided pressure-sensitive adhesive tape.

  In the present invention, a resin film is laminated on one surface of a foam substrate via an adhesive layer, an adhesive layer (a1) is laminated on the surface of the resin film, and the other surface of the foam substrate is The double-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer (a2) laminated on the surface, wherein the adhesive layer is a colored adhesive layer solves the above problem.

In the present invention, a resin film is laminated on one surface of the foam substrate with an adhesive layer on one surface of the foam substrate, and the pressure-sensitive adhesive layer (a1) is formed on the surface of the resin film. Is a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer (a2) is laminated on the other surface of the foam base material, wherein the adhesive layer is a colored adhesive layer. Double-sided adhesive tape,
The foam base material is a foam base material having a density of 0.45 g / cm ³ or less and an interlayer strength of 10 N / cm or more, and the pressure-sensitive adhesive layer is a 25 μm thick adhesive layer having a thickness of 25 μm. The pressure-sensitive adhesive tape formed with the agent layer is pressure-bonded to the aluminum plate in an environment of a temperature of 23 ° C. and a relative humidity of 65% RH using a 2 kg roller in one reciprocation, and the temperature is 23 ° C. and the relative humidity. The second adhesive tape is characterized by being a pressure-sensitive adhesive layer having a 180 ° peeling adhesive strength of 10 N / 20 mm or more at a peeling speed of 300 mm / min after standing in an environment of 50% RH for 1 hour. Solve the problem.

  The double-sided pressure-sensitive adhesive tape of the present invention can easily identify the difference between the pressure-sensitive adhesive layers constituting the front and back. Therefore, in the operation of bonding the adherend using the double-sided pressure-sensitive adhesive tape, even if the direction of sticking the double-sided pressure-sensitive adhesive tape is determined, an error in the direction of sticking the double-sided pressure-sensitive adhesive tape can be prevented, As a result, the yield of the finally obtained joined product can be increased.

  In addition, the double-sided pressure-sensitive adhesive tape of the present invention has a suitable impact resistance due to the above-described configuration, and when a certain force is applied, the foam base material causes an interlaminar crack and can be suitably disassembled. is there. Moreover, the residue of the double-sided pressure-sensitive adhesive tape affixed to the adherend can be easily peeled off and removed. For this reason, when an impact such as dropping is applied to an electronic device using the double-sided pressure-sensitive adhesive tape of the present invention, the component is not easily detached, and can be disassembled with a constant force. Can suppress cracking and distortion. Further, it is possible to efficiently dismantle a specific part from a defective product such as the electronic device or a recycled product. Furthermore, the residue of the double-sided pressure-sensitive adhesive tape such as adhesive residue remaining on the surface of the adherend can be easily peeled off and removed.

  The double-sided pressure-sensitive adhesive tape of the present invention as described above is used, for example, for fixing parts of small electronic devices, particularly for fixing thin plate-like rigid parts such as protection panels, image display modules, and thin batteries of information display units of small electronic devices. It can be suitably applied to.

It is the conceptual diagram which looked at the test piece used for the test for impact tests from the upper surface. It is the conceptual diagram which looked at the test piece used for the test for impact tests from the upper surface. It is a conceptual diagram of the test method of an impact resistance test.

  In the double-sided pressure-sensitive adhesive tape of the present invention, a resin film is laminated on one surface of a foam base material via an adhesive layer, and a pressure-sensitive adhesive layer (a1) is laminated on the surface of the resin film. A double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer (a2) is laminated on the other surface of the material, wherein the adhesive layer is a colored adhesive layer.

[Foam substrate]
The foam substrate for use in the present invention, it is preferable to use a density of 0.45 g / cm ³ or ^less, using what is 0.1g / cm ³ ~0.45g / cm 3 can be more ^preferably, it is used as a ^{0.15g / cm 3 ~0.42g / cm 3} , to obtain a double-sided adhesive tape having a suitable dismantling properties when applied constant force Therefore, it is more preferable.

  In addition, as the foam base material used in the present invention, it is preferable to use a material having an interlayer strength of 10 N / cm or more, more preferably a material having a strength of 10 N / cm to 50 N / cm, It is more preferable to use a material having a density of 10 N / cm to 25 N / cm because both a suitable dismantling property and a suitable impact resistance can be achieved. In addition, by using the foam base material, it is possible to easily peel off a residue such as glue remaining on the surface of an adherend such as a part after disassembly.

  The interlayer strength can be measured by the following method. Attach a pressure-sensitive adhesive layer having a thickness of 50 μm to both sides of the foam base material (one that does not peel off from the adherend and the foam base material during the following high-speed peel test) one by one, and then at 40 ° C. Aged for 48 hours to produce a double-sided adhesive tape for measuring interlayer strength. Next, a double-sided pressure-sensitive adhesive tape sample having a width of 1 cm and a length of 15 cm (in the flow direction and width direction of the foam base material) lined with a 25 μm-thick polyester film on one side of the pressure-sensitive adhesive surface at 23 ° C. and 50% RH A polyester film having a thickness of 50 μm, a width of 3 cm, and a length of 20 cm is pressure-applied by one reciprocation of a 2 kg roller and allowed to stand at 60 ° C. for 48 hours. Then, after further standing at 23 ° C. for 24 hours, the side bonded to the polyester film having a thickness of 50 μmm at 23 ° C. and 50% RH is fixed to a mounting jig of a high-speed peeling tester, and the polyester having a thickness of 25 μm is fixed. The maximum strength when the film is pulled in the direction of 90 degrees at a tensile speed of 15 m / min and the foam is torn is measured.

  As the foam base material used in the present invention, it is preferable to use one having a 25% compressive strength of 500 kPa or less, more preferably 10 kPa to 300 kPa, and more preferably 10 kPa to 200 kPa. It is more preferable to use, it is more preferable to use what is 30 kPa to 180 kPa, and it is preferable to use what is 50 kPa to 150 kPa, and it is possible to achieve both suitable impact resistance and dismantling properties, and adhesion. It is particularly preferable for obtaining a double-sided pressure-sensitive adhesive tape having suitable followability to the body.

  The 25% compressive strength can be measured according to JISK6767. Specifically, the double-sided pressure-sensitive adhesive tape sample cut into 25 corners is overlaid until the thickness is about 10 mm. The laminate of the double-sided adhesive tape sample is sandwiched between stainless steel plates having a larger area than the double-sided adhesive tape sample, and the laminate of the sample is about 2.5 mm (of the original thickness) at a speed of 10 mm / min at 23 ° C. 25%) Measure the strength when compressed.

Tensile strength of the foam substrate in the flow direction and the width direction to be used in the present invention is not particularly ^limited, is preferably ^{500N / cm 2 ~1300N / cm 2} , more preferably 600N ^/ cm 2 ~1200N / Cm ² . Further, the tensile elongation at the time of cutting in the tensile test is not particularly limited, but the tensile elongation in the flow direction is preferably 100% to 1200%, more preferably 100% to 1000%, and still more preferably 200%. ~ 600%. By using a foam base material having a tensile strength or tensile elongation within the above range, it is possible to suppress deterioration in workability of the double-sided pressure-sensitive adhesive tape and deterioration in pasting workability even with a foamed flexible base material. . Moreover, the ease of peeling can be provided to the double-sided pressure-sensitive adhesive tape after disassembly.

  In addition, the tensile strength of the flow direction of the above-mentioned foam base material and the width direction can be measured according to JISK6767. Specifically, the double-sided pressure-sensitive adhesive tape cut into a mark having a length of 2 cm and a width of 1 cm was measured at a tensile speed of 300 mm / min in a 23 ° C. and 50% RH environment using a Tensilon tensile tester. Maximum intensity measured under conditions.

  The average cell diameter in the flow direction and the width direction of the foam substrate is not particularly limited, but is preferably in the range of 10 μm to 500 μm, more preferably in the range of 30 μm to 400 μm, and in the range of 50 μm to 300 μm. More preferably. By using a foam substrate having an average cell diameter in the flow direction and width direction within the above range, it is possible to obtain a double-sided pressure-sensitive adhesive tape that is more excellent in adhesion to an adherend and more excellent in impact resistance. it can.

  Furthermore, the ratio of the average bubble diameter in the flow direction and the width direction (average bubble diameter in the flow direction / average bubble diameter in the width direction) is not particularly limited, but is preferably 0.2 to 4, more preferably 0.3 to 3. More preferably, it is 0.4-1. Within the above ratio range, variations in flexibility and tensile strength in the flow direction and width direction of the foam substrate are unlikely to occur.

  The average cell diameter in the thickness direction of the foam substrate used in the present invention is preferably 3 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 5 μm to 50 μm. Further, the average cell diameter in the thickness direction is preferably 1/2 or less, more preferably 1/3 or less of the thickness of the foam substrate. By making the ratio of the average cell diameter and thickness in the thickness direction within this range, it is easy to realize excellent adhesion even in the joining of rigid bodies together with disassembly and impact resistance. It is preferable because it is easy to ensure density and strength.

  The ratio of the average cell diameter in the flow direction of the foam substrate to the average cell diameter in the thickness direction of the foam substrate (average cell diameter in the flow direction / average cell diameter in the thickness direction), and the thickness of the foam substrate The ratio of the average cell diameter in the width direction of the foam substrate to the average cell diameter in the length direction (average cell diameter in the width direction / average cell diameter in the thickness direction) is preferably 1 or more, preferably 3 or more. More preferably, it is 4-25. By setting the ratio, it is easy to ensure flexibility in the thickness direction, and it is easy to realize good adhesion even in joining of rigid bodies.

  In addition, the average bubble diameter of the width direction of a foam base material, a flow direction, and thickness direction is measured in the following way. First, the foam base material is cut into 1 cm in both the width method and the flow direction. Next, the foam cell part is enlarged 200 times with a digital microscope (trade name “KH-7700”, manufactured by HiROX) at the center of the cut surface of the cut foam base material. The cross section in the width direction or the flow direction is observed on the entire length of the cut surface of the foam base material in the thickness direction of the base material. In the obtained enlarged image, all the bubble diameters of the bubbles existing on the cut surface having an actual length of 2 mm before expansion in the flow direction or the width direction are measured, and the average bubble diameter is calculated from the average value. An average bubble diameter is calculated | required from the result measured in arbitrary 10 places.

  The cell structure of the foam base material used in the present invention is preferably a closed cell structure because water or dust from the cut surface of the foam base material can be effectively prevented. The shape of the bubbles forming the closed cell structure is moderate following by using closed cells with a longer average bubble size in the flow direction, width direction, or both than the average bubble size in the thickness direction of the foam. It is preferable because it has a good cushioning property.

  As the foam base material used in the present invention, it is preferable to use a material having a thickness of 250 μm or less, more preferably a material having a thickness of 50 μm to 250 μm, and a material having a thickness of 80 μm to 200 μm. More preferably, it is particularly preferable to use a material having a thickness of 100 μm to 150 μm because even if it is thin, it is easy to achieve both suitable impact resistance and dismantling properties.

  The compressive strength, density, interlayer strength, tensile strength, and the like of the foam base material can be appropriately adjusted depending on the material and foam structure of the foam base material to be used.

  The foam base material is not particularly limited as long as it can realize the interlayer strength and the like, but a polyolefin-based foam made of polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc. Polyurethane foams, rubber foams made of acrylic rubber or other elastomers can be used, and in particular, foam with a thin closed cell structure excellent in conformity to unevenness of the adherend surface and buffer absorption Since it is easy to produce a body substrate, a polyolefin-based foam can be preferably used.

  Among polyolefin-based foams using a polyolefin-based resin, it is preferable to use a polyethylene-based resin because it is easy to produce with a uniform thickness and easily imparts suitable flexibility. In particular, the content of the polyethylene resin in the polyolefin resin is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, and 100% by mass. It is particularly preferred.

  In addition, as a polyethylene resin used for the polyolefin foam, a polyethylene resin obtained using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst has a narrow molecular weight distribution, and in the case of a copolymer, Since the copolymer component is introduced at an almost equal ratio to any molecular weight component, the polyolefin foam can be uniformly crosslinked. For this reason, since the foamed sheet is uniformly cross-linked, the foamed sheet can be easily stretched uniformly as necessary, and the thickness of the resulting polyolefin-based resin foam is easily uniformed, which is preferable.

  Further, the polyolefin resin constituting the polyolefin foam may contain a polyolefin resin other than the polyethylene resin obtained using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst. . Examples of such polyolefin resins include polyethylene resins and polypropylene resins other than those described above. In addition, polyolefin resin may be used independently or 2 or more types may be used together.

  Examples of such polyethylene resins include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, an ethylene-α-olefin copolymer containing 50% by mass or more of ethylene, and 50% of ethylene. Examples thereof include ethylene-vinyl acetate copolymers containing at least mass%, and these may be used alone or in combination of two or more. Examples of the α-olefin constituting the ethylene-α-olefin copolymer include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. Can be mentioned.

  In addition, the polypropylene resin is not particularly limited, and examples thereof include polypropylene and a propylene-α-olefin copolymer containing 50% by mass or more of propylene. The above may be used in combination. Examples of the α-olefin constituting the propylene-α-olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. Can be mentioned.

  The polyolefin-based foam may be cross-linked. When producing a polyolefin-based foam by foaming a foamable polyolefin-based resin sheet with a thermally decomposable foaming agent, it is preferable to use a polyolefin-based resin sheet that has been crosslinked in advance. The degree of cross-linking prevents bubbles in the vicinity of the surface of the foam sheet from breaking when the foam base material is stretched, thereby causing surface roughness, suppressing a decrease in adhesive layer adhesion, and impact resistance. 5% by mass to 60% by mass is preferable and 10% by mass to 55% by mass is more preferable in obtaining a double-sided pressure-sensitive adhesive tape having excellent properties and vibration characteristics.

  Next, a method for producing a polyolefin resin foam will be described. The method for producing the polyolefin resin foam is not particularly limited. For example, a polyolefin resin containing 40% by mass or more of a polyethylene resin obtained by using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst, and A foamable polyolefin resin composition containing a heat decomposable foaming agent, a foaming aid, and a colorant for coloring the foam in black or white is supplied to an extruder and melt-kneaded. A step of producing a foamable polyolefin resin sheet by extruding the foamed polyolefin resin sheet, a step of crosslinking the foamable polyolefin resin sheet, a step of foaming the foamable polyolefin resin sheet, and melting or A process to stretch the foamed sheet by softening and stretching in either or both of the flow direction or width direction And a method of containing. In addition, the process of extending | stretching a foam sheet should just be performed as needed, and may be performed in multiple times.

  And as a method of crosslinking the polyolefin resin foam substrate, for example, a method of irradiating an expandable polyolefin resin sheet with ionizing radiation, an organic peroxide is blended in advance in the expandable polyolefin resin composition Examples of the method include heating the obtained expandable polyolefin resin sheet to decompose the organic peroxide, and these methods may be used in combination.

  Examples of ionizing radiation include electron beams, α rays, β rays, and γ rays. The dose of ionizing radiation is appropriately adjusted so that the gel fraction of the polyolefin resin foam substrate is within the above-mentioned preferable range, but a range of 5 kGy to 200 kGy is preferable. Moreover, since it is easy to obtain a uniform foamed state, it is preferable to irradiate ionizing radiation on both surfaces of the expandable polyolefin resin sheet, and it is more preferable that the doses irradiated on both surfaces are the same.

  Examples of the organic peroxide include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis ( t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α ′ -Bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexyne-3, benzoyl peroxide, cumyl peroxyneodecanate, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-di (ben (Zoylperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxyallyl carbonate and the like may be mentioned, and these may be used alone or in combination of two or more.

  The amount of the organic peroxide used is sufficient to crosslink the expandable polyolefin resin sheet and to suppress the residue of decomposition of the organic peroxide in the resulting crosslinked polyolefin resin foam sheet. The range is preferably 0.01 parts by mass to 5 parts by mass and more preferably 0.1 parts by mass to 3 parts by mass with respect to 100 parts by mass of the polyolefin resin.

  The amount of the thermally decomposable foaming agent may be appropriately determined according to the foaming ratio of the polyolefin resin foam base material. However, the double-sided pressure-sensitive adhesive tape provided with a predetermined foaming ratio and excellent in tensile strength and compression recovery. Is preferably in the range of 1 to 40 parts by mass, more preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the polyolefin-based resin.

  Further, the method for foaming the expandable polyolefin resin sheet is not particularly limited, and examples thereof include a method of heating with hot air, a method of heating with infrared rays, a method using a salt bath, and a method using an oil bath. May be used in combination. Among them, the method of heating with hot air or the method of heating with infrared rays is preferable because there is little difference between the front and back surfaces of the polyolefin resin foam substrate surface.

  The stretching of the foam base material may be performed after foaming the foamable polyolefin resin sheet to obtain the foam base material, or may be performed while foaming the foamable polyolefin resin sheet. In addition, after foaming the foamable polyolefin resin sheet to obtain a foam base material, when the foam base material was stretched, the melted state during foaming was maintained without cooling the foam base material. The foam base material may be stretched continuously, or after the foam base material is cooled, the foam base material may be stretched again by heating the foamed sheet to a molten or softened state.

  Here, the molten state of the foam base material refers to a state in which the temperature of the both surfaces of the foam base material is heated above the melting point of the polyolefin resin constituting the foam base material. The softening of the foam base material means a state in which the foam base material is heated to a temperature of 20 ° C. or higher and lower than the melting point temperature of the polyolefin resin constituting the foam base material. . By stretching the foam base material, the foam of the foam base material can be produced by stretching the foam base material in a predetermined direction and deforming the foam base material so that the aspect ratio of the foam is within a predetermined range.

  Furthermore, in the extending | stretching direction of a foam base material, it extends | stretches toward the flow direction or the width direction of a elongate foamable polyolefin resin sheet, or toward a flow direction and the width direction. When the foam base material is stretched in the flow direction and the width direction, the foam base material may be stretched simultaneously in the flow direction and the width direction, or may be stretched separately one by one. .

  As a method of stretching the foam base material in the flow direction, for example, a long foam sheet after foaming is used rather than a speed (supply speed) at which a long foamable polyolefin resin sheet is supplied to the foaming process. A method of stretching the foam base material in the flow direction by increasing the winding speed (winding speed) while cooling, foaming rather than the speed (supply speed) of supplying the obtained foam base material to the stretching process Examples include a method of stretching the foam base material in the flow direction by increasing the speed of winding the body base material (winding speed).

  In the former method, the foamable polyolefin resin sheet expands in the flow direction by its own foaming. Therefore, when the foam base material is stretched in the flow direction, the foamable polyolefin resin sheet is foamed. In consideration of the amount of expansion in the flow direction, it is necessary to adjust the supply speed and the winding speed of the foam base so that the foam base is stretched in the flow direction more than the expansion.

  Further, as a method of stretching the foam base material in the width direction, both ends of the foam base material in the width direction are gripped by a pair of gripping members, and the pair of gripping members are gradually moved away from each other. A method of stretching the foam base material in the width direction is preferable. In addition, since the foamable polyolefin resin sheet expands in the width direction by its own foaming, when the foam base material is stretched in the width direction, expansion in the width direction due to foaming of the foamable polyolefin resin sheet. In consideration of the amount, it is necessary to adjust so that the foam base material is stretched in the width direction more than the expansion amount.

  Here, the draw ratio in the flow direction of the polyolefin-based foam is such that when the expansion ratio of the polyolefin-based resin foam base material is adjusted to a predetermined range, further excellent flexibility and tensile strength are provided. .1 to 5 times is preferable, and 1.3 to 3.5 times is more preferable.

  In addition, the draw ratio in the width direction is 1.2 to 4.5 in order to give more excellent flexibility and tensile strength by adjusting the expansion ratio of the polyolefin resin foam substrate to a predetermined range. Double is preferable, and 1.5 to 3.5 times is more preferable.

  The foam base material may be colored in order to develop design properties, light shielding properties, hiding properties, light reflectivity, and light resistance in the double-sided pressure-sensitive adhesive tape. The colorants can be used alone or in combination of two or more.

  When providing light-shielding property, concealability, and light resistance to an adhesive tape, the foam base material may be colored black. Black colorants include carbon black, graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxidation Physical black pigments and anthraquinone organic black pigments can be used. Of these, carbon black is preferred from the viewpoint of cost, availability, insulation, and heat resistance that can withstand the temperatures of the process of extruding the foamable polyolefin resin composition and the heating foaming process.

  When providing designability, light reflectivity, etc. to an adhesive tape, the foam base may be colored white. White colorants include titanium oxide, zinc oxide, aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate, barium carbonate, zinc carbonate , Aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, aluminum silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc white, talc, silica, alumina, clay, kaolin, phosphoric acid Organic white colorants such as titanium, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, etc., and organics such as silicone resin particles, acrylic resin particles, urethane resin particles, melamine resin particles And the like can be used white colorant. Of these, titanium oxide, aluminum oxide, and zinc oxide are preferred from the viewpoints of cost, availability, color tone, and heat resistance that can withstand the temperatures of the process of extruding the foamable polyolefin resin composition and the heating foaming process.

  In addition, the foamable polyolefin-based resin composition includes a foaming aid such as a plasticizer, an antioxidant, and zinc oxide, and a cell core modifier as long as the physical properties of the polyolefin-based resin foam substrate are not impaired. , Heat stabilizers, flame retardants such as aluminum hydroxide and magnesium hydroxide, antistatic agents, glass and plastic hollow balloon beads, metal powder, fillers such as metal compounds, conductive fillers, thermal conductive fillers Such a known additive may be optionally contained in the resin.

  When the additive is used, the additive is used in an amount of 0.1% by mass to 10% by mass with respect to the polyolefin-based resin in order to obtain a double-sided pressure-sensitive adhesive tape that maintains appropriate followability and cushioning properties. It is preferable to use in the range, and it is preferable to use in the range of 1% by mass to 7% by mass.

  In addition, when blending the colorant, the thermally decomposable foaming agent, the foaming auxiliary agent, etc. into the foamable polyolefin resin composition, in order to prevent color unevenness, abnormal foaming and foaming failure, before supplying to the extruder, It is preferable to masterbatch with a foamable polyolefin resin composition or a thermoplastic resin having high compatibility with the foamable polyolefin resin composition.

  In order to improve the adhesion of the foam base material to the adhesive layer and other layers, surface treatment such as corona treatment, flame treatment, plasma treatment, hot air treatment, ozone / ultraviolet treatment, and easy adhesion treatment agent coating is required. May have been made. In the surface treatment, when the wetting index by the wetting reagent is 36 mN / m or more, preferably 40 mN / m, more preferably 48 mN / m, good adhesion to the adhesive can be obtained. The foam base material with improved adhesion may be bonded to the pressure-sensitive adhesive layer in a continuous process, or may be wound once. When winding up the foam base material, the foam base material should be wound with paper such as paper, polyethylene, polypropylene, polyester film, etc. in order to prevent the blocking phenomenon between the foam base materials with improved adhesion. It is preferable to take a polypropylene film or a polyester film having a thickness of 25 μm or less.

[Resin film]
The resin film is laminated on one surface of the foam base material.

  The resin film removes a part of the residue of the double-sided adhesive tape remaining on the surface of the adherend when the sticky piece to which two or more adherends are attached is peeled off by the double-sided adhesive tape of the present invention. It becomes the support when doing. For example, when it is going to peel off the said sticking thing, a part of foam base material which comprises a double-sided adhesive tape is disassembled. In that case, an adhesive layer, a resin film, and a part of foam base material may remain in a part of a to-be-adhered body. When the residue is removed from the adherend, the residue can be easily removed from the surface of each adherend by pulling the resin film.

  Examples of the resin film include polyester resin films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, polyethylene film, polypropylene film, cellophane film, diacetyl cellulose film, triacetyl cellulose film, and acetyl cellulose butyrate film. , Polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone film, poly Etherimide film, polyimide film Fluororesin film, nylon film, mention may be made of a resin film such as an acrylic resin film.

  In addition, the resin film is used for corona treatment, flame treatment, plasma treatment, hot air treatment, ozone / ultraviolet treatment, and easy adhesion treatment agent in order to improve adhesion with other layers such as a foam substrate and an adhesive layer. Surface treatment such as coating may be performed.

  The thickness of the resin film is preferably 0.5 μm to 20 μm, more preferably in the range of 2 μm to 20 μm, further preferably in the range of 3 μm to 16 μm, and in the range of 3.5 μm to 15 μm. Is particularly preferred. By setting it as the said range, it becomes easy to implement | achieve suitable impact resistance and dismantling property, and it becomes easy to obtain the suitable followability with respect to a to-be-adhered body.

  The adhesive layer provided between the resin film and the foam is preferably an adhesive layer colored in a color such as white, black, blue, yellow, green, etc. A colored adhesive layer is preferable because the pressure-sensitive adhesive layers (a1) and (a2) can be easily identified.

  For the formation of the adhesive layer, an adhesive containing a coloring component can be used.

  As said adhesive agent, what contains a coloring component among the adhesive agent containing a urethane resin, the adhesive agent containing an acrylic resin, the adhesive agent containing a polyester resin etc. can be used, for example.

  Especially, as said adhesive agent, it is preferable to use the urethane type adhesive agent containing a urethane resin and a coloring component, The adhesive agent containing a polyether type urethane resin and a coloring component, polyester type urethane resin, and coloring It is more preferable to use an adhesive containing a component, and using a urethane-based adhesive containing a polyether-based urethane resin and a coloring component is excellent in initial adhesive force, and a dry laminating method is used. This is particularly preferable because it can be bonded at a relatively low temperature.

  As said urethane type adhesive agent, what contains urethane resins, a coloring component, and solvents, such as an organic solvent or water as needed, can be used.

  The urethane resin contained in the adhesive can be produced by reacting polyisocyanate and polyol.

  Examples of the polyisocyanate include 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diene. Aromatic polyisocyanates such as isocyanate, aliphatic polyisocyanates, polyisocyanates having an aliphatic cyclic structure, and the like can be used.

  As the polyol capable of reacting with the polyisocyanate, for example, polyether polyol, polyester polyol, polycarbonate polyol and the like can be used, and among them, polyether polyol is preferably used.

  As the polyether polyol, for example, one obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator can be used.

  Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, Trimethylolethane, trimethylolpropane and the like can be used.

  Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran.

  Examples of the polyester polyol include ring-opening polymerization of aliphatic polyester polyols and aromatic polyester polyols obtained by esterifying a low molecular weight polyol and a polycarboxylic acid, and cyclic ester compounds such as ε-caprolactone and γ-butyrolactone. Polyesters obtained by reaction, copolymerized polyesters thereof, and the like can be used.

  Examples of the low molecular weight polyol that can be used in the production of the polyester polyol include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1, 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, etc. can be used alone or in combination of two or more, ethylene glycol 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, and the like are preferably used in combination with 3-methyl-1,5-pentanediol, neopentyl glycol, or the like.

  Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, azelaic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and anhydrides thereof. Alternatively, an ester-forming derivative or the like can be used, and an aliphatic polycarboxylic acid such as adipic acid is preferably used. In addition, when using the polyester polyol which has the said aromatic cyclic structure, aromatic polycarboxylic acids, such as a terephthalic acid, an isophthalic acid, a phthalic acid, and a naphthalene dicarboxylic acid, can be used as the said polycarboxylic acid.

  Examples of the polycarbonate polyol that can be used as the polyol include those obtained by reacting a carbonate with a polyol, and those obtained by reacting phosgene with bisphenol A and the like.

  As the carbonate ester, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate, or the like can be used.

  Examples of the polyol capable of reacting with the carbonate ester include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3- Butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octane Diol, 1,9-nonanediol, 1,10-decanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-propanediol, 2 -Methyl-1,8-octanediol, 2-butyl-2-ethylpropanedio 2-methyl-1,8-octanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcin, bisphenol-A, bisphenol-F, 4,4′-biphenol A relatively low molecular weight dihydroxy compound such as can be used.

  As the polyol, in addition to the polyether polyol, polyester polyol and polycarbonate polyol, other polyols may be used in combination as required.

  Examples of the other polyol include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, dipropylene glycol, an acrylic polyol having a hydroxyl group introduced into an acrylic copolymer, and the like can be used as appropriate.

  As a method for producing a urethane resin by reacting the polyisocyanate and the polyol, for example, a urethane resin (A ′) having an isocyanate group is produced by reacting the polyisocyanate and the polyol, and then necessary. Depending on the method, a method of mixing and reacting a chain extender may be mentioned.

  The reaction between the polyisocyanate and the polyol can be performed in the presence or absence of an organic solvent such as methyl ethyl ketone or dimethylformamide.

  The reaction between the polyisocyanate and the polyol is in consideration of safety, taking care of sudden heat generation and foaming, preferably at a reaction temperature of 50 ° C to 120 ° C, more preferably 80 ° C to 100 ° C. Isocyanate and the polyol can be mixed by batch feeding, or one of them can be sequentially supplied to the other by dropping or the like, and the reaction can be carried out for about 1 to 15 hours.

  As the urethane resin, those having a weight average molecular weight in the range of 50,000 to 120,000 are preferably used.

  As said urethane type adhesive agent, what contains a hardening | curing agent with the said urethane resin can be used.

  As the curing agent, for example, isocyanate curing agent, epoxy curing agent, melamine curing agent, carbodiimide curing agent, oxazoline curing agent, aziridine curing agent and the like can be used.

  In addition, as the coloring component, for example, those generally known as pigments and dyes can be used. As the pigment, for example, a black pigment such as carbon black and a white pigment such as titanium oxide can be used, and as the dye, a natural dye, a chemical dye, or the like can be used.

  The said coloring component can be used to such an extent that the difference of each adhesive layer which comprises the front and back of a double-sided adhesive tape can be identified. Specifically, when the coloring component is contained in the range of 5% by mass to 20% by mass with respect to the total amount of the adhesive, both the discriminability and the further excellent adhesive strength can be achieved. preferable.

  Examples of a method for bonding the foam base material and the resin film using an adhesive such as the urethane-based adhesive include a dry laminating method, a non-solvent laminating method, and a wet laminating method. Among them, it is preferable to employ a dry laminating method that can efficiently perform the laminating process and can reduce the solvent that can remain in the adhesive layer.

  Specifically, as the bonding method, the adhesive is applied to the resin film using a direct gravure, and the solvent contained in the adhesive is removed by drying using a dryer or the like. A method of laminating the adhesive layer and the foam base material (dry laminating method) is preferable.

  The drying temperature is preferably 30 ° C to 100 ° C, more preferably 35 ° C to 70 ° C. The temperature when laminating the adhesive layer and the foam substrate is preferably 20 ° C. to 80 ° C., and 30 ° C. to 50 ° C. can firmly bond the resin film and the foam substrate. And it is more preferable because it is difficult to cause wrinkling of the resin film.

The coating amount of the ^adhesive, is preferably in the range of ^{0.5g / m 2 ~10g / m 2} , more preferably from ^{2g / m 2 ~6g / m 2} , than the conventional dry lamination method it is slightly more ^3g / m ² ~5g / m 2 is, since the resin film and the foam substrate can be firmly adhered, further preferred.

[Adhesive layer]
The double-sided pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer (a1) and a pressure-sensitive adhesive layer (a2). The pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2) may have the same composition, thickness and adhesive force, and each have a different composition, thickness and adhesive force. Also good.

  The pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2) were formed by providing the pressure-sensitive adhesive layer (a1) or pressure-sensitive adhesive layer (a2) having a thickness of 25 μm on a polyethylene terephthalate substrate having a thickness of 25 μm, respectively. Each pressure-sensitive adhesive tape is pressure-bonded once and twice using a 2 kg roller to an aluminum plate in an environment of a temperature of 23 ° C. and a relative humidity of 65% RH, and in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. It is preferable to use one having a 180 ° peel adhesive strength of 10 N / 20 mm or more at a peeling speed of 300 mm / min after standing for 1 hour, and preferably using 12 N / 20 mm or more. In addition to impact resistance, it is more preferable for obtaining a double-sided pressure-sensitive adhesive tape that can realize interlaminar cracking of a foam base material at the time of dismantling and has suitable dismantling properties with a constant force. The upper limit of the adhesive force of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 25 N / 20 mm or less, and more preferably 20 N / 20 mm or less.

  As the pressure-sensitive adhesive composition that can be used for forming the pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2), a pressure-sensitive adhesive composition used for a normal pressure-sensitive adhesive tape can be used. The pressure-sensitive adhesive composition that can be used for forming the pressure-sensitive adhesive layer (a1) can be the same as the pressure-sensitive adhesive composition that can be used for forming the pressure-sensitive adhesive layer (a2). May be used.

  Examples of the pressure-sensitive adhesive composition include (meth) acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, synthetic rubber-based pressure-sensitive adhesives, natural rubber-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. An acrylic polymer is a base polymer. It is preferable to use a (meth) acrylic pressure-sensitive adhesive in which additives such as a tackifier resin and a crosslinking agent are blended as necessary.

  The acrylic polymer can be produced by polymerizing monomer components such as (meth) acrylic monomers.

  As the monomer component, for example, (meth) acrylate can be used.

  Examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, and n-hexyl (meth) acrylate. , N-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like having an alkyl group having 1 to 12 carbon atoms (meta ) Acrylates, etc., and one or more of these can be used. Among them, it is preferable to use a (meth) acrylate having an alkyl group having 4 to 12 carbon atoms, and having a linear or branched alkyl group having 4 to 8 carbon atoms (meth). More preferably, an acrylate is used. In particular, as the (meth) acrylate, use of at least one of n-butyl acrylate and 2-ethylhexyl acrylate facilitates securing adhesion to the adherend and is excellent in cohesive strength and resistance to sebum. Therefore, it is preferable.

  The content of the (meth) acrylate having an alkyl group having 1 to 12 carbon atoms with respect to the total amount of the monomer components used for producing the acrylic polymer is preferably 60% by mass or more, and 80 It is more preferable that it is mass%-98.5 mass%, and it is further more preferable that it is 90 mass%-98.5 mass%.

  Moreover, when manufacturing the said acrylic polymer, a highly polar vinyl monomer can be used as an acrylic monomer. Examples of the highly polar vinyl monomer include a vinyl monomer having a hydroxyl group, a vinyl monomer having a carboxyl group, a vinyl monomer having an amide group, and one or more of these are used. It is done.

  Examples of monomers having a hydroxyl group include hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. The (meth) acrylate which has can be used.

  As vinyl monomers having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, etc. can be used, among which acrylic acid Is preferably used as a copolymerization component.

  Examples of the monomer having an amide group include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N, N-dimethylacrylamide.

  Examples of other highly polar vinyl monomers include sulfonic acid group-containing monomers such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and 2-acrylamido-2-methylpropanesulfonic acid.

  The amount of the highly polar vinyl monomer used is preferably 1.5% by mass to 20% by mass, and 1.5% by mass with respect to the total amount of monomer components used in the production of the acrylic polymer. 10 mass% is more preferable, and 2 mass% to 8 mass% is more preferable for obtaining a double-sided pressure-sensitive adhesive tape in which the cohesive strength, holding power, and adhesiveness of the pressure-sensitive adhesive are adjusted to suitable ranges. preferable.

  Moreover, when using an isocyanate type crosslinking agent with the said acrylic polymer as said adhesive composition, it is preferable to introduce | transduce into the said acrylic polymer the functional group which reacts with the isocyanate group. As the acrylic monomer that can be used in this case, for example, a vinyl monomer having a hydroxyl group is preferably used, and 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl. (Meth) acrylate is particularly preferred. The amount of the vinyl monomer having a hydroxyl group that reacts with the isocyanate-based crosslinking agent is 0.01% by mass to 1.0% by mass with respect to the total amount of the monomer components used for the production of the acrylic polymer. It is particularly preferable that the content is 0.03% by mass to 0.3% by mass.

  The acrylic polymer can be produced by polymerizing the monomer component by a known polymerization method such as a solution polymerization method, a cage polymerization method, a suspension polymerization method, or an emulsion polymerization method.

  Among these, as the polymerization method, it is preferable to employ a solution polymerization method or a bulk polymerization method in order to further improve the water resistance of the pressure-sensitive adhesive layers (a1) and (a2).

  Polymerization can be initiated by peroxides such as benzoyl peroxide and lauroyl peroxide, thermal initiation methods using azo-based thermal polymerization initiators such as azobisisobutylnitrile, acetophenone, benzoin ether, benzyl A starting method by ultraviolet irradiation using a ketal-based, acylphosphine oxide-based, benzoin-based or benzophenone-based photopolymerization initiator, or a method by electron beam irradiation can be arbitrarily selected.

  As for the molecular weight of the acrylic polymer, the weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) is 400,000 to 3,000,000, preferably 800,000 to 2,500,000.

  Here, the measurement of the molecular weight by the GPC method is a standard polystyrene conversion value measured using a GPC device (HLC-8329GPC) manufactured by Tosoh Corporation, and the measurement conditions are as follows.

Sample concentration: 0.5% by mass (THF solution)
Sample injection volume: 100 μl
Eluent: THF
Flow rate: 1.0 ml / min Measurement temperature: 40 ° C
This column: TSKgel GMHHR-H (20) 2 Guard column: TSKgel HXL-H
Detector: differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (manufactured by Tosoh Corporation)

  As the pressure-sensitive adhesive composition used in the present invention, a pressure-sensitive adhesive composition containing a tackifying resin is preferably used for the purpose of further improving the adhesion to the adherend and the surface adhesion strength. Tackifying resins include rosin, polymerized rosin, polymerized rosin ester, rosin phenol, stabilized rosin ester, disproportionated rosin ester, hydrogenated rosin ester, terpene, terpene phenol, petroleum resin A (meth) acrylate resin or the like can be used. When used in an emulsion-type pressure-sensitive adhesive composition, it is preferable to use an emulsion-type tackifying resin.

  Of these, disproportionated rosin ester tackifier resins, polymerized rosin ester tackifier resins, rosin phenol tackifier resins, hydrogenated rosin ester tackifier resins, (meth) acrylate resins, and terpene phenol resins are preferred. . One or more tackifying resins may be used. It is also preferable to use these tackifier resins and petroleum resins in combination.

  The softening point of the tackifying resin is not particularly specified, but is 30 ° C to 180 ° C, preferably 70 ° C to 140 ° C. By blending a tackifying resin with a high softening point, high adhesive performance can be expected. When a (meth) acrylate tackifying resin is used, it is preferable to use a (meth) acrylate tackifying resin having a glass transition temperature of 30 ° C. to 200 ° C., and 50 ° C. to 160 ° C. It is more preferable to use what is.

  The tackifier resin is preferably used in the range of 5 to 65 parts by mass, and in the range of 8 to 55 parts by mass, based on 100 parts by mass of the acrylic polymer. It is more preferable because the adhesion with the body can be further improved.

  As the pressure-sensitive adhesive composition of the present invention, it is preferable to use a pressure-sensitive adhesive composition containing a crosslinking agent in order to increase the cohesive strength of the pressure-sensitive adhesive layer.

  Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents. Among these, as the cross-linking agent, a cross-linking agent that is added after the completion of polymerization and causes the cross-linking reaction to proceed is preferable, and an isocyanate cross-linking agent and an epoxy cross-linking agent rich in reactivity with a (meth) acrylic polymer are used. Preferably, an isocyanate-based crosslinking agent is more preferable because adhesion with the foam base material is improved.

  Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, and the like. It is preferable to use a propane adduct or the like.

  As an index of the degree of cross-linking, the value of the gel fraction for measuring the insoluble content after the pressure-sensitive adhesive layer is immersed in toluene for 24 hours is used. The gel fraction is preferably 70% by mass or less. More preferably in the range of 20% by mass to 60% by mass, and even more preferably in the range of 25% by mass to 55% by mass, both cohesiveness and adhesiveness are good.

  The gel fraction is measured as follows.

  The pressure-sensitive adhesive composition was applied on an arbitrary release liner so that the thickness after drying was 50 μm, dried at 100 ° C. for 3 minutes, and aged at 40 ° C. for 2 days, and cut into 50 mm squares. A sample is used.

  Next, the mass (G1) of the sample before being immersed in toluene is measured in advance, and the toluene insoluble matter of the sample after being immersed in a toluene solution at 23 ° C. for 24 hours is filtered through a 300 mesh wire net. The mass (G2) of the residue after separation and drying at 110 ° C. for 1 hour is measured.

  The gel fraction is calculated according to the mass (G1) and mass (G2) obtained by the measurement and the following formula.

    Gel fraction (mass%) = (G2 / G1) × 100

  In addition to those described above, the pressure-sensitive adhesive composition may include, for example, a plasticizer, a softening agent, an antioxidant, a flame retardant, glass or plastic fiber / balloon / bead, metal powder, metal oxide, A material containing a filler such as a metal nitride, a colorant such as a pigment / dye, a leveling agent, a thickener, a water repellent, an antifoaming agent, or the like can be used.

  As the pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2), it is preferable to use one having a temperature at which the peak value of loss tangent (tan δ) at a frequency of 1 Hz is −40 ° C. to 15 ° C. By adopting a pressure-sensitive adhesive layer having a peak loss tangent in such a range, the adhesion to an adherend at room temperature can be further improved. On the other hand, when a double-sided pressure-sensitive adhesive tape excellent in drop impact resistance under a low temperature environment is required, it is preferable to employ a pressure-sensitive adhesive layer having a temperature indicated by the peak value of −35 ° C. to 10 ° C. It is more preferable to employ a pressure-sensitive adhesive layer that is 30 ° C to 6 ° C.

  The loss tangent (tan δ) at a frequency of 1 Hz is obtained from the equation of tan δ = G ″ / G ′ from the storage elastic modulus (G ′) and loss elastic modulus (G ″) obtained by dynamic viscoelasticity measurement by temperature dispersion. It is done. In the measurement of dynamic viscoelasticity, the pressure-sensitive adhesive layer formed to a thickness of about 2 mm was used with a viscoelasticity testing machine (trade name: ARES G2 manufactured by T.A. Instruments Japan). A test piece is sandwiched between parallel disks having a diameter of 8 mm, which is a measuring part, and a storage elastic modulus (G ′) and a loss elastic modulus (G ″) from −50 ° C. to 150 ° C. are measured at a frequency of 1 Hz.

  The thickness of the pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2) is preferably 5 μm to 100 μm, more preferably 10 μm to 80 μm, and more preferably 15 μm to 80 μm because it is easy to ensure adhesion with the adherend. Particularly preferred.

[Release liner]
In the double-sided pressure-sensitive adhesive tape of the present invention, release liners may be laminated on the surfaces of the pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2) constituting the same. The release liner is peeled off and removed when the double-sided pressure-sensitive adhesive tape is attached to the adherend.

  As the release liner, a transparent or opaque one can be used, and it is preferable to use a transparent one because the front and back of the double-sided pressure-sensitive adhesive tape can be easily identified.

  Examples of the release liner include those having a release treatment layer such as a silicone layer on one or both sides of the support, and having a resin layer such as a polyolefin layer on one or both sides of the support, Further, those having a release treatment layer such as a silicone layer can be used.

  Examples of the support include base paper, resin film, nonwoven fabric, cloth, foamed sheet, metal foil, or a laminate thereof. Examples of the base paper include high quality paper, medium quality paper, thin paper, glassine paper, and coated paper. Examples of the resin film include polyolefin films obtained using polyethylene, polypropylene, and the like.

  Examples of the resin layer that may be laminated on the surface of the support include a polyolefin layer, and examples of the polyolefin layer include a layer formed using polyethylene, polypropylene, and the like.

  Examples of the release treatment layer include a silicone-treated layer, a long-chain alkyl-treated layer, and a fluorine-treated layer.

[Double-sided adhesive tape]
The double-sided pressure-sensitive adhesive tape of the present invention has a suitable impact resistance even in a thin configuration, and when a certain force is applied, the foam base material can be suitably disassembled by causing an interlayer crack, and It is a double-sided pressure-sensitive adhesive tape that can easily peel off and remove residues such as glue remaining on the surface of an adherend after disassembly. For this reason, it is suitable for fixing parts for small electronic devices, especially for fixing plate-like rigid parts that are subject to large forces when dismantling protective panels, image display modules, thin batteries, etc. for information displays in small electronic devices. it can.

  Further, in the step of joining two or more adherends using the double-sided pressure-sensitive adhesive tape, even if the direction of sticking the double-sided pressure-sensitive adhesive tape may be determined, there is an error in the direction of sticking the double-sided pressure-sensitive adhesive tape. Can be prevented, and the yield of the finally obtained bonded product can be increased.

  As the double-sided pressure-sensitive adhesive tape of the present invention, for example, any one of those in which the resin film and the pressure-sensitive adhesive layer constituting it are directly laminated, and those in which they are laminated through other layers can be used. . When adding further dimensional stability to a double-sided adhesive tape, a laminated layer such as a polyester film, a light-shielding layer when providing light-shielding properties to the tape, and a light-reflecting layer when ensuring light-reflecting properties. In addition, when it is desired to impart electromagnetic shielding characteristics or thermal conductivity in the surface direction, a metal foil or a non-woven fabric plated with metal mesh conductive metal may be provided.

  As the laminate layer, various resin films such as a polyester film such as polyethylene terephthalate, a polyethylene film, and a polypropylene film can be used. Although these thicknesses are not particularly defined, 1 μm to 25 μm is preferable and 2 μm to 12 μm is more preferable in terms of followability of the foam base material. As the laminate layer, a transparent film, a light-shielding film, or a reflective film can be used depending on the purpose. When laminating the foam layer and the laminate layer, conventionally known pressure-sensitive adhesives and adhesives for dry lamination can be used.

  As the light shielding layer, those formed from an ink containing a colorant such as a pigment are easily used, and a layer made of black ink is preferably used because of its excellent light shielding properties. As the reflective layer, a layer formed from white ink can be easily used. The thickness of these layers is preferably 2 μm to 20 μm, and more preferably 4 μm to 6 μm. By setting the thickness within the range, curling of the substrate due to curing shrinkage of the ink hardly occurs, and the workability of the double-sided pressure-sensitive adhesive tape is improved.

  The double-sided pressure-sensitive adhesive tape of the present invention comprises (i) a step of laminating a resin film using an adhesive or the like on one surface of a foam substrate, and (ii) forming an adhesive layer (a1) on the surface of the resin film. And (iii) forming the pressure-sensitive adhesive layer (a2) on the other surface of the foam substrate, and laminating the release liner as necessary. It can be manufactured by going through.

  The said process (i) is a process of apply | coating and laminating | stacking the said adhesive agent on any one or both of a foam base material or a resin film.

  In the step (ii), for example, the pressure-sensitive adhesive composition is directly applied to the surface of the resin film laminated on one surface of the foam substrate and dried to form a pressure-sensitive adhesive layer (a1) ( (Direct copying method), a step of laminating a release liner on the surface as needed, or a pressure-sensitive adhesive layer (a1) formed by applying a pressure-sensitive adhesive composition to a release liner and drying and then foaming In this step, the pressure-sensitive adhesive layer (a1) is bonded to the surface of the resin film laminated on one surface of the body substrate (transfer method).

  In the step (iii), the pressure-sensitive adhesive composition is directly applied to the other surface (the surface opposite to the surface on which the resin film is laminated) of the foam substrate, and then dried. (A2) is formed (direct copying method), and a pressure-sensitive adhesive layer (a2) is formed by applying a pressure-sensitive adhesive composition to a release liner or the like by laminating a release liner on the surface, or by drying. ) Is formed, and then the pressure-sensitive adhesive layer (a2) is bonded to the other surface of the foam substrate (transfer method).

  In addition, when using the adhesive containing an acrylic polymer and a crosslinking agent as an adhesive which forms an adhesive layer, after producing a double-sided adhesive tape by the said method, for example, Preferably it is 20 to 50 degreeC. Preferably, aging for 2 to 7 days in an environment of 23 ° C. to 45 ° C. further improves the adhesion between the foam substrate and the resin film and the adhesive layer, and stabilizes the adhesive physical properties. This is preferable.

  The thickness of the double-sided pressure-sensitive adhesive tape of the present invention can be suitably adjusted according to the mode to be used, and if it is 300 μm or less, it is easy to contribute to thinning of a small electronic device, and is preferably 80 μm to 300 μm. More preferably, it is more preferably 100 μm to 300 μm. The double-sided pressure-sensitive adhesive tape of the present invention has suitable impact resistance and dismantling properties even in the thin configuration.

  Since the double-sided pressure-sensitive adhesive tape of the present invention has suitable impact resistance and dismantling properties due to the above configuration, it is a component of a small electronic device, for example, a protection panel or an image display module of an information display unit of a small electronic device, a thin battery , Speakers, receivers, piezoelectric elements, printed circuit boards, flexible printed circuit boards (FPCs), digital camera modules, sensors, other modules, cushion materials such as polyurethane and polyolefin, rubber parts, decorative parts and various parts It can be suitably applied to fixing and the like. In particular, the present invention can be suitably applied to fixing thin plate-like rigid parts such as a protection panel, an image display module, and a thin battery for an information display unit of a small electronic device.

(Preparation of pressure-sensitive adhesive composition (A))
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 97.97 parts by mass of n-butyl acrylate, 2.0 parts by mass of acrylic acid, 0.03 mass of 4-hydroxybutyl acrylate Part, 0.1 part by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator was dissolved in a solvent consisting of 100 parts by mass of ethyl acetate, polymerized at 70 ° C. for 12 hours, and the weight average molecular weight was A 2 million (polystyrene equivalent) acrylic copolymer was obtained. Next, with respect to 100 parts by mass of the acrylic copolymer, 25 parts by mass of “Superester A100” (glycerin ester of disproportionated rosin) manufactured by Arakawa Chemical Co., Ltd. and “Pencel D135” (polymerized rosin pentamer manufactured by Arakawa Chemical Co., Ltd.) Erythritol ester) 5 parts by mass and Mitsui Chemicals FTR 6100 (styrene petroleum resin) 20 parts by mass were added, and ethyl acetate was added and mixed uniformly to obtain an adhesive composition (a) having a nonvolatile content of 40% by mass.

  100 parts by mass of the pressure-sensitive adhesive composition (a) and 1.3 parts by mass of “Coronate L-45” (isocyanate-based crosslinking agent, non-volatile content 45% by mass) manufactured by Nippon Polyurethane Co., Ltd. are stirred for 15 minutes. The pressure-sensitive adhesive (A) was obtained. The adhesive (A) had a 180 ° peel-off adhesive strength of 12 N / 20 mm. The 180 ° peel adhesion is a value measured by the following method.

[Adhesive strength of adhesive layer by 180 ° peeling]
After the pressure-sensitive adhesive layer (A) is applied to the release-treated surface of the 75 μm-thick polyethylene terephthalate film after the release treatment so that the thickness of the pressure-sensitive adhesive layer after drying is 25 μm, and dried at 80 ° C. for 3 minutes. Then, it was bonded to a polyethylene terephthalate substrate having a thickness of 25 μm and aged in a 40 ° C. environment for 48 hours to obtain an adhesive tape.

  The pressure-sensitive adhesive tape is pressure-bonded once and twice with a 2 kg roller against an aluminum plate in an environment of a temperature of 23 ° C. and a relative humidity of 65% RH, and in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. The strength when peeled 180 ° at a peeling speed of 300 mm / min after standing for 1 hour was measured. The 180 ° peel adhesive strength of the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive (B) described later was also measured by the same method as described above.

(Preparation of pressure-sensitive adhesive composition (B))
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 93.4 parts by mass of n-butyl acrylate, 3.5 parts by mass of acrylic acid, 3 parts by mass of vinyl acetate, 2-hydroxy 0.1 part by weight of ethyl acrylate and 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator are dissolved in a solvent consisting of 100 parts by weight of ethyl acetate and polymerized at 70 ° C. for 12 hours. Thus, an acrylic copolymer having a weight average molecular weight of 1,600,000 (in terms of polystyrene) was obtained. Next, 30 parts by mass of “Superester A100” (glycerin ester of disproportionated rosin) manufactured by Arakawa Chemical Co., Ltd. and 25 parts by mass of FTR6100 (styrene-based petroleum resin) manufactured by Mitsui Chemicals are used with respect to 100 parts by mass of the acrylic copolymer. 5 parts by weight of “Pencel D135” (pentaerythritol ester of polymerized rosin) manufactured by Arakawa Chemical Industries, Ltd. was added and mixed uniformly with ethyl acetate to obtain an adhesive composition (b) having a nonvolatile content of 38% by mass. .

  100 parts by mass of the pressure-sensitive adhesive composition (b) and 1.3 parts by mass of “Coronate L-45” (isocyanate-based crosslinking agent, non-volatile content: 45% by mass) manufactured by Nippon Polyurethane Co., Ltd. are stirred for 15 minutes. To obtain an adhesive (B). The adhesive strength of the pressure-sensitive adhesive (B) was 13.7 N / 20 mm.

Example 1
The pressure-sensitive adhesive (A) prepared above was applied to the peel-treated surface of a 75 μm-thick polyethylene terephthalate film that had been peel-treated, so that the thickness of the pressure-sensitive adhesive layer after drying was 25 μm. The polyethylene terephthalate film which has a 25-micrometer-thick adhesive layer was produced by drying for minutes.

  In addition, the pressure-sensitive adhesive (A) was applied to the peel-treated surface of a 75 μm-thick polyethylene terephthalate film that had been peel-treated, so that the thickness of the pressure-sensitive adhesive layer after drying was 15 μm, and then at 80 ° C. for 3 minutes. By drying, a polyethylene terephthalate film having a pressure-sensitive adhesive layer having a thickness of 15 μm was produced.

Next, black polyolefin-based foam (1) (thickness 100 μm, density 0.40 g / cm ³ , interlayer strength 12.6 N / cm, 25% compression strength: 103 kPa, tensile strength in the flow direction: 1084 N / cm ² , Tensile strength in the width direction: 790 N / cm ² , manufactured by Sekisui Chemical Co., Ltd., surface with a wetting index of 54 mN / m by corona treatment), a resin film made of polyethylene terephthalate (thickness 6 μm) Was laminated by using a urethane-based white adhesive described later to prepare a laminate.

  As the urethane-based white adhesive, a polyester polyol having a number average molecular weight of 2,000 obtained by reacting 1,4-butanediol, neopentyl glycol and adipic acid, polyoxytetramethylene glycol, ethylene glycol, and A urethane-based adhesive comprising a dimethylformamide solution [non-volatile content: 30% by mass] of a urethane resin having a weight average molecular weight of 100,000 obtained by reacting 4,4′-diphenylmethane diisocyanate, and the non-volatile content of the urethane-based adhesive A urethane-based white adhesive obtained by mixing with white ink (ink containing titanium oxide) in an amount such that the content of titanium oxide was 10% by mass was used.

  After pasting the polyethylene terephthalate film having the 25 μm thick adhesive layer on the resin film side of the laminate and pasting the polyethylene terephthalate film having the 15 μm thick adhesive layer on the foam side of the laminate The film was laminated at 23 ° C. with a roll having a linear pressure of 5 kg / cm. Thereafter, aging was performed in an environment of 40 ° C. for 48 hours to obtain a double-sided pressure-sensitive adhesive tape having a thickness of 150 μm. In addition, the gel fraction of the adhesive (A) layer which comprises the said double-sided adhesive tape was 42.5 mass%. The gel fraction was calculated based on the difference in mass before and after the immersion by immersing the double-sided pressure-sensitive adhesive tape in toluene at room temperature for 24 hours. Hereinafter, the gel fraction when the pressure-sensitive adhesive (B) was used was also calculated by the same method as described above.

(Example 2)
A double-sided pressure-sensitive adhesive tape having a thickness of 140 μm was obtained in the same manner as in Example 1 except that the thickness after drying of the pressure-sensitive adhesive layer on the resin film side of the laminate was changed to 15 μm.

(Example 3)
A double-sided pressure-sensitive adhesive tape having a thickness of 200 μm was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer on the resin film side and foam side of the laminate was changed to 45 μm.

Example 4
Black polyolefin foam (2) instead of black polyolefin foam (1) (thickness: 80 μm, density 0.40 g / cm ³ , interlayer strength 10.2 N / cm, 25% compressive strength: 92 kPa, flow direction Tensile strength: 1062 N / cm ² , tensile strength in the width direction: 962 N / cm ² , manufactured by Sekisui Chemical Co., Ltd., with a surface having a wetting index of 54 mN / m by corona treatment), and the lamination A double-sided pressure-sensitive adhesive tape having a thickness of 120 μm was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer on the resin film side of the body was changed to 15 μm.

(Example 5)
Black polyolefin foam (3) instead of black polyolefin foam (1) (thickness: 100 μm, density 0.45 g / cm ³ , interlayer strength 16.2 N / cm, 25% compressive strength: 190 kPa, flow direction Except for using a tensile strength of 964 N / cm ² , tensile strength in the width direction: 861 N / cm ² , manufactured by Sekisui Chemical Co., Ltd., and having a surface with a wetting index of 54 mN / m by corona treatment) A double-sided pressure-sensitive adhesive tape having a thickness of 150 μm was obtained in the same manner as in Example 1.

(Example 6)
A double-sided pressure-sensitive adhesive tape having a thickness of 200 μm was obtained in the same manner as in Example 5 except that the thickness of the pressure-sensitive adhesive layer on the resin film side and foam side of the laminate was changed to 45 μm.

(Example 7)
Black polyolefin foam (4) instead of black polyolefin foam (1) (thickness: 140 μm, density 0.40 g / cm ³ , interlayer strength 19.1 N / cm, 25% compressive strength: 130 kPa, flow direction The tensile strength in the width direction: 994 N / cm ² , the tensile strength in the width direction: 713 N / cm ² , manufactured by Sekisui Chemical Co., Ltd., the surface having a wetness index of 54 mN / m by corona treatment), and the lamination A double-sided pressure-sensitive adhesive tape having a thickness of 200 μm was obtained in the same manner as in Example 1, except that the thickness of the pressure-sensitive adhesive layer on the resin film side and foam side of the body was changed to 25 μm.

(Example 8)
Other than using a resin film made of polyethylene terephthalate (thickness 3 μm) instead of a resin film made of polyethylene terephthalate (thickness 6 μm), and the thickness of the pressure-sensitive adhesive layer on the resin film side after drying was 28 μm Obtained the double-sided adhesive tape by the method similar to Example 1. FIG.

Example 9
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that a resin film made of polyethylene terephthalate (thickness 16 μm) was used instead of a resin film made of polyethylene terephthalate (thickness 6 μm).

(Example 10)
A double-sided pressure-sensitive adhesive tape having a thickness of 150 μm was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive composition (B) was used instead of the pressure-sensitive adhesive composition (A). The gel fraction of the pressure-sensitive adhesive (B) layer constituting the double-sided pressure-sensitive adhesive tape was 40% by mass.

(Comparative Example 1)
Instead of the urethane-based white adhesive, 1,4-butanediol, neopentyl glycol, and adipic acid are reacted with a polyester polyol having a number average molecular weight of 2,000, polyoxytetramethylene glycol, ethylene glycol, and Example 4 except that a urethane-based adhesive composed of a dimethylformamide solution [nonvolatile content: 30% by mass] of a urethane resin having a weight average molecular weight of 100,000 obtained by reacting 4,4′-diphenylmethane diisocyanate is used. A double-sided pressure-sensitive adhesive tape having a thickness of 150 μm was obtained by the same method.

(Comparative Example 2)
A double-sided pressure-sensitive adhesive tape having a thickness of 150 μm was obtained in the same manner as in Example 1 except that the resin film was not used and the thickness of the pressure-sensitive adhesive layer after drying was 25 μm on both sides.

  The following evaluation was performed about the foam base material used by the said Example and comparative example, and the double-sided adhesive tape obtained by the said Example and comparative example. The results obtained are shown in the table.

[Thickness of foam substrate and adhesive tape]
Measurement was performed using a dial series gauge G type manufactured by Ozaki Seisakusho. In the case of an adhesive tape, measurement was performed after the release film was peeled off.

[Density of foam substrate]
The density was measured according to JISK6767. About 15 cm ^{3 of} a foam base material cut into a 4 cm × 5 cm rectangle was prepared, and the mass was measured to determine the density.

[Interlayer strength of foam substrate]
Attach a pressure-sensitive adhesive layer having a thickness of 50 μm to both sides of the foam base material (one that does not peel off from the adherend and the foam base material during the following high-speed peel test) one by one, and then at 40 ° C. Aged for 48 hours, a double-sided pressure-sensitive adhesive tape for measuring interlayer strength was produced. Next, a double-sided pressure-sensitive adhesive tape sample having a width of 1 cm and a length of 15 cm (in the flow direction and width direction of the foam base material) lined with a 25 μm-thick polyester film on one side of the pressure-sensitive adhesive surface at 23 ° C. and 50% RH The polyester film having a thickness of 50 μm, a width of 3 cm, and a length of 20 cm was pressure-applied with one reciprocation of a 2 kg roller, and left at 48 ° C. for 48 hours. After standing at 23 ° C. for 24 hours, the side bonded with the 50 μm thick polyester film at 23 ° C. and 50% RH is fixed to a mounting jig of a high-speed peel tester, and the 25 μm thick polyester film is pulled at a speed. The maximum strength was measured when the foam was torn in the 90 degree direction at 15 m / min.

[Tensile strength of foam substrate]
The tensile strength in the flow direction and width direction of the foam substrate was measured according to JISK6767. A foam substrate having a marked line length of 2 cm and a width of 1 cm was measured using a Tensilon tensile tester in an environment of 23 ° C. and 50% RH under measurement conditions of a tensile speed of 300 mm / min. The maximum strength of the measured value obtained is the tensile strength of the foam substrate.

[25% compressive strength of foam substrate]
The 25% compressive strength of the foam substrate was measured according to JISK6767. Samples cut into 25 squares were stacked to a thickness of about 10 mm. The foam base material was sandwiched with a stainless steel plate having a larger area than the foam base material, and the foam base material was compressed at a rate of 10 mm / min at 23 ° C. by about 2.5 mm (25% of the original thickness). The intensity of time was measured.

[Measurement of average cell diameter of foam substrate]
First, the foam base material was cut into 1 cm in both the width method and the flow direction. Next, the foam cell part is enlarged 200 times with a digital microscope (trade name “KH-7700”, manufactured by HiROX) at the center of the cut surface of the cut foam base material. The cross section in the width direction or the flow direction was observed on the entire length of the cut surface of the foam base material in the thickness direction of the base material. In the obtained enlarged image, all the bubble diameters of the bubbles existing on the cut surface having an actual length of 2 mm before expansion in the flow direction or the width direction were measured, and the average bubble diameter was calculated from the average value. The average bubble diameter was determined from the results of measurement at any 10 locations.

[Identity evaluation method]
Each pressure-sensitive adhesive layer constituting the double-sided pressure-sensitive adhesive tape obtained in Examples and Comparative Examples was visually confirmed, and the pressure-sensitive adhesive layer laminated on the resin film and the pressure-sensitive adhesive layer laminated on the other surface of the foam base material Those that could be visually distinguished from each other were evaluated as “◯”, and those that could not be distinguished were evaluated as “×”.

[Easy disassembly]
1) A test piece was prepared by cutting the double-sided pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples into a length of 2 cm (the flow direction of the foam base material) and a width of 1 cm. Two pieces of the test piece were attached to the center of a polycarbonate plate having a length of 2.5 cm, a width of 4.0 cm, and a thickness of 2 mm with an interval of 2 cm in the width direction.

  2) The end of a polyethylene terephthalate film with a length of 20 cm, a width of 1.5 cm, and a thickness of 50 μm is fixed to the back surface of the polycarbonate plate, and the polyethylene terephthalate film is wound so that it passes through two double-sided adhesive tapes. It was. At that time, the center of the width of the polyethylene terephthalate film was made to coincide with the center of the two double-sided adhesive tapes.

  3) The polycarbonate plate on which the polyethylene terephthalate film was wound and fixed was adhered and fixed to the surface of an aluminum plate having a length of 20 cm and a width of 20 cm so that the double-sided adhesive tape was in contact, and pressure-bonded using a 2 kg weight. The specimen was allowed to stand at 23 ° C. and 50% RH for 72 hours.

  4) The end of the polyethylene terephthalate film of the test piece was pulled up in the 90 ° direction with respect to the aluminum plate, and the polycarbonate plate was peeled off. The peeling state of the double-sided adhesive tape at that time was observed.

  A: The entire surface (100%) of the double-sided pressure-sensitive adhesive tape was broken and peeled between the layers of the foam substrate.

  A: 90% or more and less than 10% of the double-sided pressure-sensitive adhesive tape was broken and peeled between the layers of the foam substrate.

  X: The part which destroyed between the layers of the foam base material of a double-sided adhesive tape was less than 90%.

[Peelability]
The end part of the residue of the double-sided pressure-sensitive adhesive tape remaining after the test for easy disassembly was picked up and peeled off slowly by manual peeling at 600 mm / min in the 135 ° direction. The state of peeling and removal of the residue at that time was observed.

  A: All (100%) of the residue of the double-sided pressure-sensitive adhesive tape was peeled off.

  A: 90% or more and less than 10% of the residue of the double-sided pressure-sensitive adhesive tape was peeled and removed.

  (Triangle | delta): The part by which the residue of the double-sided adhesive tape was peeled and removed was 50 to 90 percent.

  X: The part where the residue of the double-sided pressure-sensitive adhesive tape was peeled and removed was less than 50%.

[Impact resistance test]
1) Weak adhesive surface of two double-sided adhesive tapes 40mm long and 5mm wide on an acrylic plate (Mitsubishi Rayon Co., Ltd. Acrylite L "trade name", hue: transparent) with a thickness of 2mm and an external dimension of 50mm x 50mm Are attached in parallel with an interval of 40 mm (Fig. 1), and then an ABS plate having a thickness of 2 mm and an outer shape of 150 mm x 100 mm (manufactured by Sumitomo Bakelite Co., Ltd., Tuface R "trade name" hue: natural, no grain, the same applies hereinafter) It stuck on the center part of (FIG. 2). After reciprocating pressure with a 2 kg roller, the test piece was left at 23 ° C. for 1 hour.

  2) A U-shaped measuring table (made of aluminum with a thickness of 5 mm) having a length of 150 mm, a width of 100 mm and a height of 45 mm is installed on the base of the DuPont impact tester (manufactured by Tester Sangyo Co., Ltd.). The test piece was placed on top with the acrylic plate facing down (FIG. 3). A stainless steel striker with a diameter of 25 mm and a mass of 300 g from the ABS plate side was changed in height by 10 cm and dropped 5 times at 10-second intervals for each height on the center of the ABS plate. The height when peeling or destruction was observed was measured.

○: No peeling or breaking of the tape after the test even at a height of 60 cm ×: peeling or breaking of the tape occurred at a height of 60 cm or less

1 Double-sided adhesive tape 2 Acrylic plate 3 ABS plate 4 U-shaped measuring table 5 Strike core

Claims (7)

A resin film is laminated on one surface of the foam substrate via an adhesive layer, an adhesive layer (a1) is laminated on the surface of the resin film, and an adhesive on the other surface of the foam substrate. a double-sided pressure-sensitive adhesive tape layer (a2) is laminated, the adhesive layer is, Ri colored adhesive layers der, the foam substrate, density of 0.45 g / cm ³ or less, the interlayer strength 10N / Cm to 25 N / cm foam base material, and either one or both of the pressure-sensitive adhesive layer (a1) and the pressure-sensitive adhesive layer (a2) have a thickness of 25 μm on a polyethylene terephthalate base material having a thickness of 25 μm. The pressure-sensitive adhesive tape formed by providing the pressure-sensitive adhesive layer (a1) or the pressure-sensitive adhesive layer (a2) is bonded to an aluminum plate at a temperature of 23 ° C. and a relative humidity of 65% RH using a 2 kg roller. Crimped in one reciprocation, temperature 23 ° C, relative Double-sided adhesive tape 180 ° peel adhesion at a peel rate 300 mm / min after allowing to stand for 1 hour under an environment of RH degrees 50% and wherein the adhesive layer der Rukoto above 10 N / 20 mm. The double-sided pressure-sensitive adhesive tape according to claim 1, having a total thickness of 300 µm or less. The tensile strength of the foam substrate is ^double-sided adhesive tape according to claim 1 or 2 which is ^{500N / cm 2 ~1300N / cm 2} . The average cell diameter in the flow direction of the foam substrate is in the range of 10 μm to 500 μm, the average cell diameter in the width direction is in the range of 10 μm to 500 μm, and the average cell diameter in the thickness direction is in the range of 3 μm to 100 μm. The ratio of the average bubble diameter in the flow direction and the width direction (average bubble diameter in the flow direction / average bubble diameter in the width direction) is in the range of 0.2-4. Double-sided adhesive tape as described. The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the resin film is a film obtained using a polyester resin. The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the adhesive layer is a layer containing a urethane resin and a coloring component. The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 6, which is used for fixing two or more parts constituting an electronic device.

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