CN107849398B

CN107849398B - Adhesive tape, heat sink, electronic device, and method for manufacturing adhesive tape

Info

Publication number: CN107849398B
Application number: CN201680042385.5A
Authority: CN
Inventors: 山上晃; 今井克明
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2015-08-06
Filing date: 2016-08-02
Publication date: 2020-12-22
Anticipated expiration: 2036-08-02
Also published as: JP6601522B2; JPWO2017022749A1; KR20180020218A; KR102025167B1; JP2018127634A; CN107849398A; WO2017022749A1

Abstract

The invention relates to an adhesive tape, which is provided with more than 2 adhesive parts (B) on at least one surface (a) side of a support body (A), and is characterized in that a region without the adhesive parts (B) is arranged between the more than 2 adhesive parts (B), and the region is communicated with the end part of the adhesive tape. The present invention is useful for providing a thin adhesive tape which can rapidly release air bubbles from the interface with an adherend to prevent air bubbles from remaining at the interface and has excellent adhesion.

Description

Adhesive tape, heat sink, electronic device, and method for manufacturing adhesive tape

Technical Field

The present invention relates to a thin adhesive tape that can be used in, for example, a manufacturing place of electronic equipment.

Background

Adhesive tapes are widely used in, for example, manufacturing places of electronic devices such as OA devices and home electric appliances because of their excellent workability and high adhesion reliability.

In recent years, the electronic devices are required to have higher functions, smaller sizes, and thinner shapes, and in particular, portable electronic terminals such as personal computers, digital video cameras, electronic notebooks, mobile phones, PHS's, smart phones, game devices, and electronic books are required to have further smaller sizes and thinner shapes. Accordingly, the adhesive tapes and the like constituting the portable electronic terminals are also required to be thin.

As the above-described thin adhesive tape, a double-sided adhesive tape is known which has adhesive layers on both sides of a core material, the adhesive layers containing, for example, an acrylate copolymer having a weight average molecular weight of 70 ten thousand or more and a butyl acrylate unit content of 90 mass% or more and a tackifier as main components, and the tackifier content being 40 to 60 mass%, the total thickness of the core material and the double-sided adhesive layers being 30 μm or less, and the thickness of each of the double-sided adhesive layers being 2 to 10 μm (see, for example, patent document 1).

However, when the adhesive tape is required to be further thinned, air bubbles tend to remain at the interface between the adhesive tape and the adherend when the adhesive tape is thinned and the adherend is bonded to each other, and as a result, appearance defects due to swelling of the adhesive tape and the like may occur.

Further, since the remaining air bubbles serve as thermal resistance, when the thin adhesive tape is used for bonding a heat radiating member to a heat generating member or the like, heat radiation may be reduced.

In addition, in order to achieve the above-mentioned reduction in thickness, in the reduction in thickness of the adhesive agent layer, it has been studied that the adhesive agent layer which is thin and provided with only the release path of the bubbles may not maintain a practically sufficient adhesive force.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-1699327

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide an adhesive tape which can rapidly release air bubbles from an interface with an adherend to prevent air bubbles from remaining at the interface and has excellent adhesion.

Means for solving the problems

The present inventors have solved the above-mentioned problems with an adhesive tape having 2 or more adhesive parts (B) on at least one surface (a) side of a support (a), wherein a region having no adhesive part (B) is present between the 2 or more adhesive parts (B), and the region communicates with an end of the adhesive tape.

Effects of the invention

The adhesive tape of the present invention is very thin, rapidly discharges bubbles from the interface with the adherend, hardly retains bubbles at the interface, and has excellent adhesion, and therefore, the adhesive tape can be suitably used for adhesion of a case constituting an electronic device such as a portable electronic terminal, a heat-radiating member such as a graphite sheet, and a heat-generating member such as a rechargeable battery.

Drawings

Fig. 1 is a plan view of the adhesive tape having a substantially diamond-shaped adhesive part as viewed from the adhesive part side of the adhesive tape.

Fig. 2 is a plan view of the adhesive tape having a substantially circular adhesive part as viewed from the adhesive part side of the adhesive tape.

Fig. 3 is a plan view of the adhesive tape having a substantially hexagonal adhesive part as viewed from the adhesive part side of the adhesive tape.

Fig. 4 is a plan view of the adhesive tape having a substantially quadrangular adhesive part as viewed from the adhesive part side of the adhesive tape.

Fig. 5 is a side view of a graphite composite sheet.

Fig. 6 is a plan view of the surface having the adhesive part of the adhesive tape obtained in example 20.

Fig. 7 is a plan view of the surface having the adhesive part of the adhesive tape obtained in comparative example 2.

Detailed Description

The adhesive tape of the present invention is an adhesive tape having 2 or more adhesive parts (B) on at least one surface (a) side of a support (a), wherein a region having no adhesive part (B) is present between the 2 or more adhesive parts (B), and the region communicates with an end of the adhesive tape.

Specific embodiments of the adhesive tape of the present invention include an adhesive tape having 2 or more adhesive sections (B) directly on at least one surface (a) side of the support (a), and an adhesive tape having the adhesive sections (B) on at least one surface (a) side of the support (a) with another layer interposed therebetween.

When a double-sided adhesive tape is used as the adhesive tape, the following may be used: a double-sided adhesive tape having a structure in which 2 or more specific adhesive parts (B) are provided on both surfaces (a) of the support body (a), and a region having no adhesive part (B) is provided between the 2 or more adhesive parts (B), the region being communicated with an end of the adhesive tape; alternatively, the double-sided adhesive tape may have a structure in which 2 or more specific adhesive parts (B) are provided on one surface (a) side of the support body (a), a region having no adhesive part (B) is provided between the 2 or more adhesive parts (B), the region communicates with an end of the adhesive tape, and an adhesive layer is provided on the other surface side of the support body (a) over the entire surface thereof.

Between the 2 or more adhesive portions (B), there are regions where no component constituting the adhesive portion (B) is present, or regions that may be present to such an extent that the adhesiveness is not exhibited. Therefore, when the adhesive tape of the present invention is viewed from the side surface direction, it is observed that the adhesive part (B) is formed in a convex shape with respect to the surface (a) of the support (a).

The adhesive tape of the present invention includes: the region without the adhesive part (B) among the 2 or more adhesive parts (B) is communicated with a part of the end part (edge part) of the adhesive tape. By using the adhesive tape having the above-described configuration, when the adhesive tape is attached to an adherend, bubbles are discharged to the outside from the interface between the adhesive tape and the adherend through the region, and therefore, appearance defects due to expansion or the like of the adhesive tape can be prevented, and excellent thermal conductivity, adhesion, and the like can be maintained.

The adhesive tape of the present invention is preferably an adhesive tape having a total thickness of 50 μm or less, particularly preferably an adhesive tape having a thickness of 20 μm or less, more preferably an adhesive tape having a thickness of 2 μm to 15 μm, even more preferably an adhesive tape having a thickness of 3 μm to 10 μm, and particularly preferably an adhesive tape having a thickness of 3 μm to 6 μm, for example, in view of contributing to the reduction in thickness of a portable electronic terminal or the like. The adhesive tape of the present invention has excellent adhesion and thermal conductivity while maintaining excellent ease of bubble release even when it is very thin as described above. The total thickness of the adhesive tape is a thickness of the adhesive tape measured by a method using a dial gauge according to JIS K6783 under the conditions that the contact surface of the dial gauge is a flat surface, the diameter thereof is 5mm, and the load is 1.23N, and does not include the thickness of the release liner. The thickness can be measured, for example, by a thickness meter TH-102 manufactured by the Tester industry.

The adhesive tape of the present invention is preferably an adhesive tape having an adhesive strength of 1N/20mm to 12N/20mm, more preferably an adhesive tape having an adhesive strength of 1.5N/20mm to 10N/20mm, and is preferably an adhesive tape having an adhesive strength of 3N/20mm to 8N/20mm, in order to obtain an adhesive tape which is easy to remove air bubbles from the interface between an adherend and the adhesive tape even when it is thin and has an excellent adhesive strength. On the other hand, when further excellent adhesiveness is required, the adhesive tape is more preferably an adhesive tape having an adhesive strength of 4N/20mm to 10N/20mm, and more preferably an adhesive tape having an adhesive strength of 4.5N/20mm to 8N/20 mm.

The adhesion is a value measured according to JISZ 0237. Specifically, the adhesion is a value measured by the following method: the adhesive tape having a surface having an adhesive part (B) and a polyethylene terephthalate film with a thickness of 25 μm as a backing was placed on a clean and smooth stainless steel plate (BA plate), pressed by reciprocating the upper surface thereof once with a 2kg roller, left at 23 ℃ and 50% RH for 1 hour or 24 hours, and then peeled at a speed of 0.3m/min in the 180 ℃ direction. The backing is applied to a surface not having the adhesive portion (B), and is not applied to a surface having the adhesive portion (B) which is a constituent element of the present invention. In the case where the adhesive tape has the adhesive sections (B) on both surfaces, the surface having any of the adhesive sections (B) is used as a backing.

The adhesive tape of the present invention is preferably an adhesive tape having an adhesive holding force of 2mm or less, more preferably an adhesive tape having an adhesive holding force of 0.5mm or less, and still more preferably an adhesive tape having an adhesive holding force of 0.1mm or less, in terms of preventing peeling of an adherend or a support (a) with time due to repulsive force or the like even when the adhesive tape is thin, and particularly preventing the peeling when the adhesive tape is used at a high temperature.

The adhesion holding force is a value measured according to JISZ 0237. Specifically, the adhesion holding force is set to the following value: the surface of an adhesive tape having an adhesive part (B) backed with an aluminum foil 50 μm thick was overlaid on a clean and smooth stainless steel plate (hairline), and the upper surface was pressed by reciprocating once with a 2kg roller, and then left at 23 ℃ and 50% RH for 1 hour to prepare a test piece. Next, the stainless steel plate constituting the test piece was fixed in a vertical direction in an environment of 100 ℃, and left for 24 hours in a state where a load of 100g was applied to the lower end portion of the adhesive tape constituting the test piece, and then the offset distance between the stainless steel plate and the adhesive tape was measured with a vernier caliper.

[ support (A) ]

The adhesive tape of the present invention is preferably formed by using a support having a thickness of 1 to 20 μm, more preferably 1 to 10 μm, more preferably 1 to 4 μm, and even more preferably 1.5 to 2.5 μm, since the adhesive tape can be made thinner and the air bubbles can be easily removed from the interface between the surface having the adhesive part (B) and the adherend, and as a result, the appearance defects, the deterioration of the properties such as thermal conductivity and adhesion, etc., due to the swelling of the adhesive tape, etc., can be more effectively prevented, and therefore, the adhesive tape is more preferably used.

As the support (a), for example, a sheet-like support obtained using a resin can be used.

As the resin that can be used for producing the support (a), two or more of the following may be used alone or in combination: polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); amide resins such as polyamide (nylon) and wholly aromatic polyamide (aromatic polyamide); acrylic resins such as polybutyl acrylate, polyethyl acrylate, and polymethyl methacrylate (PMMA); styrene resins such AS polystyrene, acrylonitrile-styrene copolymer (AS resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin); polyether ketones such as polyether ether ketone (PEEK) and polyether ketone; polyether sulfone (PES), polysulfone, polyvinyl chloride (PVC), polyphenylene sulfide (PPS), Polyimide (PI), polyamideimide, Polyetherimide (PEI), polyesterimide, Polycarbonate (PC), polyacetal, polyarylether (polyphenylene ether and the like), polyphenylene sulfide, polyarylate, polyurethane, epoxy resin, and the like.

Among them, the support (a) is preferably a polyester film, and more preferably a polyethylene terephthalate film, from the viewpoints of less variation in thickness, excellent tensile strength and processability, and economy (cost). When the polyester film obtained by biaxial stretching is used as the polyester film, the strength of the support (a) and the adhesive tape obtained using the same can be further improved, and therefore, it is preferable.

The support (a) may be produced by molding the resin into a sheet. When polyester is used as the resin, the support (a) can be produced, for example, by the following method.

First, a polyester sheet, which may be dried or undried, and a master batch containing a colorant or a colorant at a high concentration as necessary are melt-kneaded using a kneading extruder or the like.

Next, the kneaded mixture was extruded from a die, and rapidly cooled and solidified on a rotary cooling drum, thereby obtaining an undrawn polyester film in a substantially amorphous state.

Examples of a method for further improving the smoothness of the polyester film include the following methods: a method for shortening the residence time of the polyester in the extruder; when a single-screw extruder is used, a method of drying the raw material such as the obtained polyester so that the water content is preferably 50ppm or less, more preferably 30ppm or less; a method in which a vent is provided in the case of using a twin screw extruder, and the process is carried out under a reduced pressure atmosphere of preferably 40 kpa or less, more preferably 30 kpa or less, and still more preferably 20 kpa or less; for example, a method of electrostatic adhesion or liquid coating adhesion is used to improve the adhesion between the polyester film and the rotary cooling drum.

As a method for stretching the polyester film obtained by the above method, for example, the unstretched sheet is preferably stretched 2 to 6 times at 70 to 145 ℃ in the longitudinal direction, uniaxially stretched in the longitudinal direction, then stretched 2 to 6 times at 90 to 160 ℃ in the transverse direction, and subjected to a heat-setting step.

The polyester film is preferably relaxed by 0.1% to 20% in the longitudinal direction and/or the transverse direction in the highest temperature region of the heat treatment and/or the cooling region at the outlet of the heat treatment. The stretched polyester film obtained by the above-described method may be further stretched longitudinally and further stretched transversely as necessary.

The support (a) obtained by the above method may be composed of a single layer, or may be composed of a plurality of layers containing the same or different resins.

In addition, as the support (a), in order to further improve the adhesion with the adhesive part (B) and other adhesive layers, for example, a support obtained by subjecting one or both surfaces thereof to oxidation treatment such as chromic acid treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, ionizing radiation treatment, or the like; a support such as a primer layer is formed by using a coating agent or the like.

[ adhesive part (B) ]

Next, the adhesive part (B) constituting the adhesive tape of the present invention will be described.

The adhesive part (B) is provided on one side or both sides of the support (a) directly or via another layer, as described above.

Between the 2 or more adhesive portions (B), there are regions where no component constituting the adhesive portion (B) is present, or regions that may be present to such an extent that the adhesiveness is not exhibited.

Further, the present invention has the following configuration: the region without the adhesive part (B) among the 2 or more adhesive parts (B) is communicated with a part of the end part (edge part) of the adhesive tape. By using the adhesive tape having the above-described configuration, when the adhesive tape is attached to an adherend, bubbles can be easily removed from the interface between the adherend and the adhesive tape, and therefore, it is possible to prevent appearance defects caused by swelling of the adhesive tape and the like, and to maintain excellent thermal conductivity, adhesive strength, and the like.

The shape of the adhesive part (B) is preferably substantially a quadrangle, a hexagon, a circle or the like when the adhesive tape of the present invention is viewed from the side of the one surface (a) of the support (a), and is preferably a circle because bubbles (gas-releasing property) are easily released from the interface with the adherend (gas-releasing property) and a good adhesive strength can be maintained.

The substantially circular shape is not particularly limited, and the ratio [ maximum diameter/minimum diameter ] of the maximum diameter to the minimum diameter of any 1 adhesive part is preferably 1 to 4. More preferably 1 to 2, and most preferably 1 to 1.5. As an example of the substantially circular shape, a shape as shown in fig. 6 can be cited. The adhesive parts of the above shapes are basically independent of each other, but as shown in fig. 6, there may be a portion in which 2 or more adhesive parts are connected.

The above-mentioned substantially quadrangular shape may be a substantially square shape, a substantially rectangular shape, a substantially trapezoidal shape, a substantially rhombic shape, or the like, and is preferable because bubbles are easily discharged from the interface with the adherend (gas discharge property) and a good adhesive force can be maintained in the case of a substantially rhombic shape.

The "substantially" of the substantially quadrangular shape, the substantially hexagonal shape, and the like includes the following shapes: for example, when a release liner or the like is attached to the surface of the adhesive part (B) or when the adhesive tape is wound in a roll shape, the corners of the quadrangle and the hexagon are rounded and the straight line part is curved by pressing the adhesive part (B).

The substantially square corner is preferably substantially rhombus-shaped with an angle of less than 90 ° to the corner in the moving direction of the adhesive tape, and is more preferably in the range of 45 ° to 70 °, since bubbles are easily discharged from the interface with the adherend (gas discharge property) and a good adhesive strength can be maintained.

In addition, any of the adhesive part (B1) and the adhesive part (B2) constituting the 2 or more adhesive parts (B) preferably do not align with the moving direction and the width direction of the adhesive tape.

In addition, the adhesive tape is often cut into an arbitrary shape depending on the application. In this case, by arranging the adhesive part (B1) and the adhesive part (B2) so as not to face the moving direction and the width direction, when the adhesive tape is cut at an arbitrary position, the adhesive part (B) is present in a part of the end part thereof, and therefore, the peeling of the adhesive tape can be suppressed.

A distance between an arbitrary adhesive part (B1) selected from the 2 or more adhesive parts (B) and another adhesive part (B2) (which is present closest) adjacent to the adhesive part (B1) is preferably 0.5mm or less, more preferably 0.05mm to 0.2mm, even more preferably 0.06mm to 0.15mm, and even more preferably 0.08mm to 0.13mm, and bubbles are easily discharged from the interface with the adherend (gas discharge property), and good adhesion can be maintained, which is particularly preferable.

The size of each optional adhesive part (B1) selected from the adhesive parts (B) is preferably 0.001mm in area²～100mm²More preferably 0.01mm²～25mm²More preferably 0.015mm²～16mm²0.02mm in diameter²～5mm²In the case of the adhesive, bubbles are easily discharged from the interface with the adherend (gas discharge property), and a good adhesive force can be maintained, which is particularly preferable.

The number of the adhesive sections (B) is preferably 10 to 1000000, more preferably 1000 to 50000, and particularly preferably 5000 to 40000 in the range of the area of the adhesive tape of the present invention (square of 5cm in the moving direction and 5cm in the width direction), because bubbles (gas-releasing property) are easily released from the interface with the adherend and a good adhesive force can be maintained.

Further, the adhesive tape is preferably one having 120 to 2000 adhesive parts in a predetermined area (square of 1cm in the moving direction and 1cm in the width direction) of the adhesive tape, more preferably one having 280 to 1600 adhesive parts, and still more preferably one having 520 to 1200 adhesive parts, from the viewpoint that bubbles (gas-releasing property) are easily released from the interface with the adherend at the time of adhesion, a good adhesion can be maintained, and appearance defects due to the shape of the adhesive parts can be effectively prevented even when the adherend such as a graphite sheet is further thinned.

The number of the adhesive sections can be determined by observing an arbitrary range of the adhesive tape (a square having a movement direction of 1cm and a width direction of 1 cm) or (a square having a movement direction of 5cm and a width direction of 5 cm) with an electron microscope and counting the number of the adhesive sections.

The ratio of the area having the adhesive portion (B) to the area of the one surface (a) is preferably 10% to 99%. More preferably 20% to 90%, still more preferably 30% to 80%, and most preferably 35% to 80%. In the above range, a substantially circular adhesive portion described later can be formed, and as a result, an adhesive tape which can easily discharge bubbles from the interface with the adherend (gas discharge property) and can maintain good adhesion can be efficiently produced, and therefore, the adhesive tape is particularly preferable. The ratio of the region is the ratio of the area of the adhesive portion (B) in the area of the square tape having a width of 5cm in the moving direction and 5cm in the width direction.

The peak temperature of the loss tangent of the dynamic viscoelasticity spectrum measured at a frequency of 1Hz by the pressure-sensitive adhesive part (B) is not particularly limited, but is preferably-30 to 20 ℃, more preferably-20 to 10 ℃, and-10 to 5 ℃, because bubbles (gas-releasing property) are easily released from the interface with the adherend and a good adhesive force can be maintained, and as a result, the appearance defects, the deterioration of the properties such as thermal conductivity, heat resistance, adhesive force, and the like, caused by the expansion and the like of the adhesive tape can be more effectively prevented, and therefore, the pressure-sensitive adhesive tape is more preferable.

In the dynamic viscoelasticity measurement, a viscoelasticity tester (trade name: ARES 2KSTD, manufactured by Rheometrics) was used to measure the storage modulus (G') and the loss modulus (G) at a frequency of 1Hz by sandwiching a test piece between parallel disks as a measurement part of the tester. The loss tangent is calculated from the formula (tan ═ G ")/(G'). The above peak temperature means a peak temperature observed in a spectrum of tan with respect to a measurement temperature region (-50 ℃ C. to 150 ℃ C.).

As the test piece, an adhesive layer having a thickness of 0.5mm to 2.5mm formed by using the adhesive used for forming the adhesive part (B) can be used.

In addition, as the test piece, a test piece in which a plurality of adhesive tapes of the present invention are laminated and the total thickness of the adhesive layers is 0.5mm to 2.5mm can be used. When the test piece having the different structure is used, the peak temperature does not substantially change when the total thickness of the adhesive agent layer (B) occupied in the test piece is the same, although the tan value changes. Therefore, any test piece can be used for the measurement of the peak temperature.

The adhesive part (B) is preferably an adhesive part having a gel fraction of 10 to 60 mass%, more preferably an adhesive part having a gel fraction of 20 to 55 mass%, and even when the adhesive part having a gel fraction of 30 to 50 mass% is used, the surface shape of the adhesive part (B) is easily maintained even when the adhesive part is thin, and therefore, the change with time is easily prevented, and bubbles can be easily removed from the interface between the adherend and the adhesive part (B), and as a result, the appearance defects, the performance degradation such as thermal conductivity, heat resistance, and adhesive strength, caused by the expansion of the adhesive tape, and the like can be more effectively prevented, and therefore, the adhesive part (B) is more preferably used. The gel fraction is a value measured by the following method.

The gel fraction is a value measured by the following method.

The adhesive was applied to the release-treated surface of the release liner (C) so that the thickness after drying became 50 μm, and then dried at 100 ℃ for 3 minutes and cured at 40 ℃ for 2 days to form an adhesive layer.

The adhesive layer was cut into a square having a length of 50mm and a width of 50mm to prepare a test piece.

The mass of the test piece (G1) was measured, and then the test piece was immersed in toluene at 23 ℃ for 24 hours.

After the impregnation, the mixture of the test piece and toluene was filtered using a 300-mesh metal net, thereby extracting insoluble components in toluene. The insoluble matter was dried at 110 ℃ for 1 hour, and the mass of the resultant product was measured (G2).

The gel fraction was calculated based on the mass (G1), the mass (G2) and the following formula.

Gel fraction (% by mass) of (G2/G1). times.100

The adhesive part (B) is preferably an adhesive part having a thickness of 1 to 6 μm, and when an adhesive part having a thickness of 2 to 5 μm is used, bubbles can be easily removed from the interface between the adherend and the adhesive part (B), and as a result, appearance defects, such as expansion of the adhesive tape, and performance degradation such as thermal conductivity, heat resistance, and adhesive strength can be more effectively prevented, and therefore, the adhesive part (B) is more preferably used. The thickness of the adhesive part (B) is measured by a method using a dial gauge according to JIS K6783 under the conditions that the contact surface of the dial gauge is a flat surface, the diameter thereof is 5mm, and the load is 1.23N.

The adhesive part (B) can be formed using a known adhesive such as an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, a polyester adhesive, a styrene-diene block copolymer adhesive, a vinyl alkyl ether adhesive, a polyamide adhesive, a fluorine adhesive, a creep property improving adhesive, or a radiation-curable adhesive. Among them, the use of an adhesive part obtained by using an acrylic adhesive as the adhesive part (B) is preferable because the adhesive reliability is excellent.

When the adhesive tape of the present invention is an adhesive tape having adhesive sections or adhesive layers on both sides of the support, the adhesive sections or adhesive layers may have the same composition and gel fraction, or may have different compositions and gel fractions.

As the acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive containing an acrylic polymer can be used.

As the acrylic polymer, a polymer obtained by polymerizing a monomer component containing a (meth) acrylic monomer such as an alkyl (meth) acrylate can be used.

As the alkyl (meth) acrylate, for example, 2 or more of the following may be used alone or in combination: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like. Among these, the alkyl (meth) acrylate is preferably an alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms, and more preferably an alkyl (meth) acrylate in which the alkyl group has 4 to 18 carbon atoms. The alkyl group may be a linear or branched alkyl group.

The alkyl (meth) acrylate having 4 to 18 carbon atoms of the acryloyl group is preferably butyl (meth) acrylate in order to obtain an adhesive tape which can easily prevent a change with time, easily discharge bubbles from an interface with an adherend (gas discharge properties), and maintain good adhesion force, because the surface shape of the adhesive agent layer (B) is easily maintained.

As the (meth) acrylic monomer, in addition to the above, two or more of the following may be used alone or in combination: a monomer having a carboxyl group such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, or an anhydride thereof; sulfonic acid group-containing monomers such as sodium vinylsulfonate; monomers having a cyano group such as acrylonitrile; amide group-containing monomers such as acrylamide, methacrylamide, N-vinylpyrrolidone and N, N-dimethyl (meth) acrylamide; hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylate and glycerol dimethacrylate; amino group-containing monomers such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; monomers having an epoxy group such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; examples of the monomer include a monomer having an isocyanate group such as 2-methacryloyloxyethyl isocyanate, triethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and divinylbenzene.

As the monomer, in addition to the (meth) acrylic acid monomer, aromatic vinyl compounds such as styrene and substituted styrene; olefins such as ethylene, propylene and butadiene; vinyl esters such as vinyl acetate; vinyl chloride, and the like.

The acrylic polymer can be produced by polymerizing the monomers by a method such as solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization, and the solution polymerization is preferably used in order to improve the production efficiency of the acrylic polymer.

The solution polymerization method includes, for example, a method of mixing and stirring the monomer, the polymerization initiator, and the organic solvent at a temperature preferably ranging from 40 ℃ to 90 ℃ to perform radical polymerization.

As the polymerization initiator, for example, peroxides such as benzoyl peroxide and lauroyl peroxide; azo thermal polymerization initiators such as azobisisobutyronitrile; acetophenone-based photopolymerization initiator, benzoin ether-based photopolymerization initiator, benzoin ketal-based photopolymerization initiator, acylphosphine oxide-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzophenone-based photopolymerization initiator, and the like.

The acrylic polymer obtained by the above method may be in a state of being dissolved or dispersed in an organic solvent in the case of being produced by, for example, a solution polymerization method.

The acrylic polymer obtained by the above method is preferably an acrylic polymer having a weight average molecular weight of 30 to 120 ten thousand, more preferably an acrylic polymer having a weight average molecular weight of 40 to 110 ten thousand, and is preferably an acrylic polymer having a weight average molecular weight of 50 to 100 ten thousand in order to obtain an adhesive tape having more excellent adhesive strength and ease of bubble removal even when the adhesive tape is thin.

The weight average molecular weight is a value calculated by measuring by gel permeation chromatography (GPC method) and converting into standard polystyrene. Specifically, the weight average molecular weight can be measured under the following conditions using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh corporation.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)

Sample injection amount: 100 μ l

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 ml/min

Measuring temperature: 40 deg.C

Main chromatographic column: TSKgel GMHHR-H (20)2 root

Protecting the chromatographic column: TSKgel HXL-H

A detector: differential refractometer

Weight average molecular weight of standard polystyrene: 1 to 2000 thousands (made by Tosoh corporation)

As the adhesive that can be used for forming the adhesive part (B), an adhesive containing a tackifier resin is preferably used in forming an adhesive part having more excellent adhesive strength, tensile strength, and tensile breaking strength.

Examples of the tackifier resin include petroleum resin-based tackifier resins such as rosin-based tackifier resin, polymerized rosin ester-based tackifier resin, rosin phenol-based tackifier resin, stabilized rosin ester-based tackifier resin, disproportionated rosin ester-based tackifier resin, hydrogenated rosin ester-based tackifier resin, terpene-phenol-based tackifier resin, and styrene-based tackifier resin.

As the above-mentioned tackifier resin, it is preferable to use a rosin-based tackifier resin and a petroleum-based tackifier resin in combination in order to obtain an adhesive tape having more excellent adhesive strength and ease of removing bubbles even when the adhesive tape is thin. The rosin-based tackifier resin and the petroleum-based tackifier resin are particularly preferably used in combination with the acrylic polymer, and in order to obtain an adhesive tape having more excellent adhesion and ease of removal of bubbles even when the adhesive tape is thin, the rosin-based tackifier resin and the petroleum-based tackifier resin are preferably used in combination with an acrylic polymer obtained by polymerizing a monomer containing butyl (meth) acrylate.

In addition, as the tackifier resin, a tackifier resin which is liquid at normal temperature is preferably used in order to further improve the initial adhesive strength of the adhesive part (B). Examples of the tackifier resin which is liquid at room temperature include processing oils, polyester plasticizers, low molecular weight liquid rubbers such as polybutene, terpene-phenol resins, and commercially available YP-90L manufactured by An-Productal chemical Co.

The tackifier resin is preferably used in a range of 20 to 60 parts by mass with respect to 100 parts by mass of the acrylic polymer, and more preferably in a range of 30 to 55 parts by mass in order to obtain an adhesive tape having a further excellent adhesive strength.

As the adhesive constituting the adhesive part (B), an adhesive containing a softening agent, a plasticizer, a filler, an antioxidant, a colorant, and the like as needed in addition to the acrylic polymer and the like can be used.

Among these, the use of a crosslinking agent is preferable because the gel fraction of the adhesive part (B) can be adjusted to an appropriate range, and as a result, the shape of the adhesive part (B) is easily maintained, and therefore, changes over time are easily prevented, bubbles can be easily removed from the interface between the adherend and the adhesive layer (B), and an adhesive tape having excellent adhesive strength can be obtained.

As the crosslinking agent, for example, an isocyanate crosslinking agent or an epoxy crosslinking agent is preferably used.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, naphthalene-1, 5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, and the like, and tolylene diisocyanate adducts such as tolylene diisocyanate and trimethylolpropane-modified tolylene diisocyanate are preferably used. The tolylene diisocyanate adduct is a substance having a structure derived from tolylene diisocyanate in the molecule, and a commercially available product thereof includes, for example, CORONATE L (manufactured by Nippon polyurethane industries Co., Ltd.).

When the isocyanate crosslinking agent is used, an acrylic polymer having a hydroxyl group is preferably used as the acrylic polymer. The acrylic polymer having a hydroxyl group may be produced using, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, etc., as monomers used for producing the acrylic polymer, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are more preferably used.

Further, as the epoxy crosslinking agent, for example, TETRAD X and TETRAD C available from Mitsubishi gas chemical, E-05X available from Mitsubishi chemical, and the like can be used.

When the epoxy crosslinking agent is used, an acrylic polymer having an acid group is preferably used as the acrylic polymer. As the monomer used for producing the acrylic polymer having an acid group, for example, (meth) acrylic acid, acrylic acid dimer, itaconic acid, crotonic acid, maleic anhydride, and the like are preferably used, and (meth) acrylic acid is more preferably used.

As the adhesive that can be used for forming the adhesive part (B), an adhesive containing a solvent as necessary is preferably used. The adhesive is preferably an adhesive whose viscosity is adjusted to a range of 0.1 to 1000 mPas, more preferably an adhesive whose viscosity is adjusted to a range of 1 to 200 mPas, and even more preferably an adhesive whose viscosity is adjusted to a range of 10 to 100 mPas, since the adhesive (B) can be easily formed into a predetermined shape.

[ method for producing adhesive tape ]

The adhesive tape of the present invention can be produced by, for example, intermittently applying the adhesive to at least one surface (a) side of the support (a) and drying the adhesive to form the adhesive portion (B).

The adhesive tape may be produced by intermittently applying the adhesive to both sides of the support (a) and drying the adhesive.

The adhesive is preferably applied to at least one surface (a) of the support (a) in a batch manner by an application method such as a gravure coating method or a slot die coating method, and is preferably applied by a direct gravure coating method.

In addition, the adhesive tape may be manufactured as follows: for example, after the adhesive is applied to the surface of the release liner and dried to form the adhesive portion (B), the adhesive portion (B) is transferred to at least one surface (a) side of the support (a).

The adhesive tape of the present invention may be produced, for example, by using the above-mentioned release liner, and then, if necessary, peeling off the release liner and attaching another release liner.

The adhesive tape of the present invention has excellent adhesive strength even when it is extremely thin, and therefore can be suitably used in a manufacturing place of electronic equipment such as a portable electronic terminal required to be thin. Even when the gap between adherends (the portion to which the adhesive tape is applied) is in a very narrow range of 20 μm or less in width, the adherends can be firmly bonded.

Further, since the adhesive tape is likely to release air bubbles from the interface between the adherend and the adhesive part (B), the adhesive tape can be suitably used for fixing a heat sink, fixing a magnetic sheet, and the like, which may cause a reduction in performance due to the remaining air bubbles.

(use in fixing radiator fins)

Many electronic devices such as portable electronic terminals are equipped with members that generate heat when used. Examples of the heat generating member include a rechargeable battery and a circuit board.

In order to prevent malfunction of the electronic device, it is preferable to avoid a local high temperature of a part of the electronic device due to heat generation of the members. Therefore, a heat dissipating member such as a heat sink is often attached to the heat generating member or a member adjacent thereto (e.g., a metal member used as a frame member for imparting rigidity to the electronic device) for the purpose of dissipating the heat.

As the heat dissipating member, for example, a graphite sheet or a graphene sheet is preferably used.

The graphite sheet includes two kinds, i.e., an artificial graphite sheet and a natural graphite sheet.

Examples of the artificial graphite sheet include a thermally decomposed graphite sheet obtained by thermally decomposing an organic film such as a polyimide film in an inert gas atmosphere at a high temperature.

Examples of the natural graphite sheet include a graphite sheet obtained by subjecting natural graphite to acid treatment, expanding the natural graphite by heating, and then pressing the obtained graphite powder to form a sheet.

The graphite sheet is preferably a graphite sheet having less wrinkles, and more preferably an artificial graphite sheet having less wrinkles, in terms of further excellent heat dissipation properties.

The thickness of the graphite sheet is preferably 10 μm to 100 μm, and is preferably 15 μm to 50 μm in view of contributing to the reduction in thickness of electronic devices such as portable electronic terminals.

On the other hand, since the graphite sheet is brittle, it is generally used in a state of a graphite composite sheet having an adhesive tape adhered to one surface or both surfaces thereof.

As shown in fig. 5, for example, the graphite composite sheet is preferably used which has a structure in which a graphite sheet is sealed with a single-sided adhesive tape and a double-sided adhesive tape in order to achieve both high strength and insulation of the graphite sheet.

When the graphite composite sheet is sealed (bagged) by an adhesive tape having an area larger than that of the graphite sheet, the graphite composite sheet is preferably used because it can prevent interlayer destruction, chipping, and the like of the graphite sheet and can easily realize suitable workability.

The adhesive tape of the present invention can be suitably used when the above-mentioned graphite sheet is bagged. In this case, the adhesive tape is preferably used in a state in which the surface having the adhesive portion (B) faces outward (direction of the non-graphite sheet side). Thus, when the graphite composite sheet is bonded to a heat-generating member such as a rechargeable battery or a member adjacent thereto, air bubbles can be effectively prevented from remaining at the interface therebetween.

The graphite composite sheet may be bonded to the member by the following steps: placing the graphite composite sheet on the surface of the member, for example, and lightly press-bonding the graphite composite sheet to the member to temporarily bond the graphite composite sheet to the member; and a step of pressing the adhesive to firmly bond them with a roller or the like after the temporary bonding. In the temporary bonding step, air bubbles are generally present at the interface between the member and the graphite composite sheet. However, in the case of the graphite composite sheet using the adhesive tape of the present invention, the bubbles are rapidly removed from the interface when the pressure is applied by the roller or the like.

In addition, a surface protective film is often attached to the graphite composite sheet for the purpose of preventing damage to the surface thereof. The surface protective film is usually removed after the graphite composite sheet is bonded to the member.

According to the adhesive tape of the present invention, since the adhesive tape can be firmly adhered to an adherend such as a member after the removal of the air bubbles, the graphite composite sheet is less likely to be lifted and peeled off from the member when the surface protective film is removed from the graphite composite sheet.

As described above, the graphite composite sheet obtained using the adhesive tape of the present invention can prevent the presence of bubbles at the interface with an adherend such as a member, and therefore can effectively prevent the thermal resistance value of the adhesive tape from increasing due to the presence of the bubbles, and as a result, can improve the thermal conductivity in the thickness direction of the adhesive tape.

(use in magnetic sheet fixing application)

Magnetic sheets are often attached to the inside of electronic devices for the purpose of shielding electromagnetic waves emitted from members constituting the electronic devices from leaking to the outside or preventing electromagnetic waves generated from the outside from affecting the electronic devices.

Examples of the magnetic sheet include sheets obtained from Ni-based ferrite magnetic powder, Mg-based ferrite magnetic powder, Mn-based ferrite magnetic powder, Ba-based ferrite magnetic powder, Sr-based ferrite magnetic powder, Fe-Si alloy powder, Fe-Ni alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, Fe-Si-Cr alloy powder, iron powder, Fe-based amorphous bodies, Co-based amorphous bodies, and Fe-based nanocrystals.

As the magnetic sheet, a thick magnetic sheet is generally preferably used in order to impart good electromagnetic wave shielding properties.

Since the adhesive tape of the present invention is very thin as described above, a magnetic sheet having a maximum thickness can be used as the magnetic sheet.

The magnetic sheet is preferably used in the form of a magnetic composite sheet having an adhesive tape attached to one or both surfaces thereof for the purpose of providing excellent insulation properties and high strength.

Examples

Hereinafter, examples of the present invention will be described, and more specifically, the present invention will be described.

Preparation example 1 adhesive a

With azobisisobutyronitrile 0.2 part by mass as a polymerization initiator, 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid and 0.02 part by mass of 4-hydroxybutyl acrylate were solution-polymerized in an ethyl acetate solution at 80 ℃ for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 90 ten thousand.

5 parts by mass of "D-135" (polymerized rosin ester, manufactured by Mitsukawa chemical Co., Ltd.), "20 parts by mass of" KE-100 "(disproportionated rosin ester, manufactured by Mitsukawa chemical Co., Ltd.), and 25 parts by mass of" FTR6100 "(petroleum resin, manufactured by Mitsui chemical Co., Ltd.) were mixed with 100 parts by mass of the acrylic polymer, and ethyl acetate was further added thereto to obtain a pressure-sensitive adhesive solution having a solid content adjusted to 40% by mass.

The above adhesive solution and 2.0 parts by mass of "NC 40" (isocyanate crosslinking agent, available from DIC corporation) were mixed and stirred to obtain adhesive a.

The adhesive layer obtained using the adhesive a had a tan peak temperature of 0 ℃ and a gel fraction of 40 mass%.

Preparation example 2 adhesive b

With azobisisobutyronitrile 0.3 part by mass as a polymerization initiator, 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid and 0.02 part by mass of 4-hydroxybutyl acrylate were solution-polymerized in an ethyl acetate solution at 90 ℃ for 6 hours to obtain an acrylic polymer having a weight average molecular weight of 50 ten thousand.

The above adhesive solution and 0.6 part by mass of "NC 40" (isocyanate crosslinking agent, available from DIC corporation) were mixed and stirred to obtain adhesive b.

The adhesive layer obtained using the adhesive b had a tan peak temperature of 0 ℃ and a gel fraction of 10 mass%.

Preparation example 3 adhesive c

The above adhesive solution and 3.3 parts by mass of "NC 40" (isocyanate crosslinking agent, available from DIC corporation) were mixed and stirred to obtain adhesive c.

The adhesive layer obtained using the adhesive c had a tan peak temperature of 0 ℃ and a gel fraction of 46% by mass.

Preparation example 4 adhesive d

The above adhesive solution and 1.2 parts by mass of "NC 40" (isocyanate-based crosslinking agent, available from DIC corporation) were mixed and stirred to obtain adhesive d.

The adhesive layer obtained using the adhesive d had a tan peak temperature of 0 ℃ and a gel fraction of 20 mass%.

Preparation example 5 adhesive e

With azobisisobutyronitrile 0.2 part by mass as a polymerization initiator, n-butyl acrylate 96.4 parts by mass, acrylic acid 3.5 parts by mass, and acrylic acid 4-hydroxyethyl ester 0.1 part by mass were solution-polymerized in an ethyl acetate solution at 80 ℃ for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 80 ten thousand.

10 parts by mass of "D-135" (a polymerized rosin ester, manufactured by Mitsukawa chemical Co., Ltd.) and 10 parts by mass of "A100" (a disproportionated rosin ester, manufactured by Mitsukawa chemical Co., Ltd.) were mixed with 100 parts by mass of the acrylic polymer, and ethyl acetate was further added thereto to obtain an adhesive solution having a solid content adjusted to 40% by mass.

The above adhesive solution and 1.3 parts by mass of "NC 40" (isocyanate crosslinking agent, available from DIC corporation) were mixed and stirred to obtain adhesive e.

The adhesive layer obtained using the adhesive e had a tan peak temperature of-15 ℃ and a gel fraction of 40 mass%.

Preparation example 6 adhesive f

With azobisisobutyronitrile 0.1 part by mass as a polymerization initiator, n-butyl acrylate 44.9 parts by mass, 2-ethylhexyl acrylate 50 parts by mass, vinyl acetate 3 parts by mass, acrylic acid 2 parts by mass, and 4-hydroxybutyl acrylate 0.1 parts by mass were solution-polymerized in an ethyl acetate solution at 70 ℃ for 10 hours to obtain an acrylic polymer having a weight average molecular weight of 80 ten thousand.

A pressure-sensitive adhesive solution having a solid content adjusted to 40 mass% was obtained by mixing 10 parts by mass of "D-135" (polymerized rosin ester, available from Mitsukawa chemical Co., Ltd.) with 100 parts by mass of the above acrylic polymer and further adding ethyl acetate.

The above adhesive solution and 1.3 parts by mass of "NC 40" (isocyanate crosslinking agent, available from DIC corporation) were mixed and stirred to obtain an adhesive f.

The adhesive layer obtained using the adhesive f had a tan peak temperature of-25 ℃ and a gel fraction of 40 mass%.

(example 1)

The adhesive a was applied to a release liner having a silicone release-treated surface on the surface of a PET film having a smooth surface (manufactured by Nippa corporation, PET25 × 1J 0L) by using a roll coater, and then dried at 100 ℃ for 1 minute to prepare an adhesive layer having a thickness of 1 μm.

Subsequently, the adhesive layer was transferred to one surface of "K100-2.0W" (polyester film, thickness 2 μm, manufactured by Mitsubishi resin Co., Ltd.) as a support to obtain a single-sided tape.

Next, the adhesive a was dot-printed on the other surface of the support constituting the single-sided adhesive tape using a gravure coater, and dried at 100 ℃ for 1 minute to obtain an adhesive tape having a total thickness of 6 μm with a substantially rhombus-shaped adhesive portion having a thickness of 3 μm as shown in fig. 1. In the above-described adhesive portions, the distance between any of the adhesive portions and the adhesive portion adjacent thereto was 0.1 mm.

On the surface of the adhesive tape having the adhesive part obtained above, "PET 25 × 1J 0L" (release liner having a silicone-based release-treated surface on the surface of a PET film having a smooth surface, manufactured by Nippa corporation) was superimposed and bonded at a line pressure of 3N/mm by a laminator.

(examples 2 to 12)

Adhesive tapes were produced in the same manner as in example 1, except that the shape and area of the adhesive part (B) and the thickness of the adhesive part (B) were changed to those described in tables 1 to 3.

(example 13)

The adhesive a was dot-printed on a release liner "PET 25 × 1J 0L" (manufactured by Nippa corporation, having a silicone-based release-treated surface on the surface of a smooth-surfaced PET film) using a gravure coater, and dried at 100 ℃ for 1 minute to form an adhesive part having a thickness of 3 μm in a substantially rhombus shape (angle of a corner portion facing the moving direction of the adhesive tape is 60 °) as shown in fig. 1. In the above-described adhesive portions, the distance between any of the adhesive portions and the adhesive portion adjacent thereto was 0.1 mm.

Then, the pressure-sensitive adhesive portion was transferred to one surface of "K100-2.0W" (polyester film, thickness 2 μm, manufactured by Mitsubishi resin Co., Ltd.) as a support to obtain a single-sided tape.

Next, the adhesive a was dot-printed on the other surface of the support constituting the single-sided tape using a gravure coater, and dried at 100 ℃ for 1 minute to form an adhesive portion having a thickness of 3 μm in a substantially rhombus shape (angle of a corner portion facing the moving direction of the adhesive tape is 60 °) as shown in fig. 1. In the above-described adhesive portions, the distance between any of the adhesive portions and the adhesive portion adjacent thereto was 0.1 mm.

In this manner, an adhesive tape having adhesive sections with a thickness of 3 μm and substantially rhombus-like shapes as shown in FIG. 1 on both sides of the support and a total thickness of 8 μm was obtained.

(example 14)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive b was used instead of the adhesive a.

(example 15)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive c was used instead of the adhesive a.

(example 16)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive d was used instead of the adhesive a.

(example 17)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive e was used instead of the adhesive a.

(example 18)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive f was used instead of the adhesive a.

(examples 19 to 25)

Adhesive tapes were produced in the same manner as in example 1, except that the shape and area of the adhesive part (B) and the thickness of the adhesive part (B) were changed to those shown in tables 4 and 5. The surface of the adhesive tape obtained in example 20 having the substantially circular adhesive portion was observed with an optical microscope at a magnification of 200 (fig. 6).

Comparative example 1

The adhesive a was applied to "PET 25 × 1J 0L" (release liner having a silicone-based release-treated surface on the surface of a PET film having a smooth surface, manufactured by Nippa corporation) using a roll coater, and then dried at 100 ℃ for 1 minute to prepare an adhesive layer having a thickness of 1 μm.

Next, the adhesive a was applied to the other surface of the support constituting the single-sided tape using a roll coater, and then dried at 100 ℃ for 1 minute to prepare an adhesive layer having a thickness of 3 μm.

Comparative example 2

The adhesive a was applied to "PET 25 × 1J 0L" (release liner having a silicone-based release-treated surface on the surface of a PET film having a smooth surface, manufactured by Nippa corporation) using a roll coater, and then dried at 100 ℃ for 1 minute to prepare an adhesive layer having a thickness of 2 μm.

Subsequently, the adhesive layer was transferred onto one surface of "K100-2.0W" (polyester film, thickness 2 μm, manufactured by Mitsubishi resin Co., Ltd.) as a support to obtain a single-sided tape.

Further, the adhesive a was applied to a support of a single-sided tape using a roll coater, and then dried at 100 ℃ for 1 minute to prepare an adhesive layer having a thickness of 2 μm. The pressure of the laminator used for transferring the adhesive layer to the support was 3N/mm.

Then, the release paper subjected to the lattice-shaped embossing treatment was bonded to the adhesive agent layer, and cured at 40 ℃ for 2 days, thereby obtaining an adhesive tape including an adhesive agent layer having an uneven shape as shown in fig. 7 on the surface of the adhesive agent layer. Fig. 7 is a view showing the surface of the adhesive layer of the adhesive tape obtained in comparative example 2, observed at a magnification of 100 times using an optical microscope.

Comparative example 3

Next, the adhesive a was applied to a release liner having a silicone-based release-treated surface on the surface of a PET film treated with a sand cushion layer, and the center line average surface roughness Ra was 0.36 μm, using a roll coater, to prepare an adhesive layer having a thickness of 2 μm, thereby coating the adhesive a on the release liner with "PSM 100 GS" (manufactured by linetec corporation). Subsequently, the adhesive layer was transferred to the other surface of the support to obtain an adhesive tape having a total thickness of 6 μm. The pressure of the laminator used for transferring the adhesive layer to the support was 3N/mm.

(method of measuring gel fraction of adhesive part)

The adhesives a to f were applied to the release-treated surface of the release liner so that the dried thicknesses thereof became 50 μm, and then dried at 100 ℃ for 3 minutes and cured at 40 ℃ for 2 days, thereby forming an adhesive layer. The adhesive layer was cut into a square having a length of 50mm and a width of 50mm, and the square was used as a test piece.

The mass of the test piece (G1) was measured, and then the test piece was immersed in toluene at 23 ℃ for 24 hours. After the impregnation, the mixture of the test piece and toluene was filtered using a 300-mesh metal net, thereby extracting insoluble components in toluene. The mass of the insoluble matter obtained by drying the insoluble matter at 110 ℃ for 1 hour was measured (G2).

Gel fraction (% by mass) of (G2/G1). times.100

(measurement of dynamic viscoelasticity)

The adhesives a to f were applied to the surface of a release liner so that the dry thickness became 50 μm, and dried to form an adhesive layer, and the adhesive layer was cured at 40 ℃ for 2 days. The cured adhesive layers were stacked until the total thickness became 2mm, and the resultant was used as a test piece.

Next, the test piece was inserted into a measuring part having a disk shape of a parallel disk with a diameter of 7.9mm by using a viscoelasticity tester (trade name: ARES 2KSTD, manufactured by Rheometric Co., Ltd.), and the storage modulus (G') and the loss modulus (G ") at-50 ℃ to 150 ℃ were measured under the conditions of a frequency of 1Hz and a temperature rise time of 1 ℃/1 minute. The loss tangent tan was calculated by the following calculation formula.

Loss tangent tan ═ G "/G'

(preparation of graphite composite sheet)

A single-sided adhesive tape "IL-05G" (manufactured by DIC) having a thickness of 104mm X5 μm was bonded to one surface of a graphite sheet having a length of 100mm X a thickness of 25 μm, and an adhesive tape obtained by cutting the adhesive tape obtained in examples and comparative examples into a size of 104mm X104 mm on the other surface of the graphite sheet.

In this case, the adhesive layer constituting the adhesive tape has a smooth surface in a direction of contact with the graphite sheet.

Subsequently, a 62 μm thick micro-adhesive single-sided tape "CPF 50(25) -SP" (manufactured by Nippa corporation) was attached to the surface of the single-sided adhesive tape "IL-05G", to obtain a graphite composite sheet.

(adhesion (1 hour after sticking))

The adhesive tapes obtained in examples and comparative examples were cut into a width of 20mm, and one of the adhesive layers was backed with a polyethylene terephthalate film having a thickness of 25 μm to prepare a test piece. The backing is performed on the surface of the adhesive layer having a smooth surface, but not on the adhesive layer corresponding to the adhesive part (B) which is a constituent element of the present invention.

The test piece was adhered to the surface of a clean and smooth stainless steel plate, and after pressurizing the upper surface thereof by reciprocating a 2kg roller once, it was left to stand at 23 ℃ and 50% RH for 1 hour according to JIS Z-0237, and then the peel adhesion (peel direction: 180 ℃ and tensile speed: 0.3m/min) was measured at 23 ℃ and 50% RH using a TENSILON tensile tester. The measurement results are shown in the column of "adhesion (1 hour after sticking)" in the table.

(adhesion (24 hours after sticking))

The test piece was stuck to the surface of a clean and smooth stainless steel plate, pressed by reciprocating the upper surface once with a 2kg roller, left to stand at 23 ℃ and 50% RH for 24 hours in accordance with JIS Z-0237, and then the peel adhesion (peel direction: 180 ℃ and tensile speed: 0.3m/min) was measured at 23 ℃ and 50% RH atmosphere using a TENSILON tensile tester. The measurement results are shown in the column of "adhesion (24 hours after sticking)" in the table.

(Retention force)

The adhesive tapes obtained in examples and comparative examples were cut into a width of 20mm, and one of the adhesive layers was backed with an aluminum foil having a thickness of 50 μm to prepare a test piece. The backing is performed on the surface of the adhesive layer having a smooth surface, but not on the adhesive layer corresponding to the adhesive part (B) which is a constituent element of the present invention.

The test piece was adhered to the surface of a clean and smooth stainless steel plate so as to have an adhesion area of 20mm × 20mm, pressed by reciprocating the upper surface once with a 2kg roller, allowed to stand at 23 ℃ and 50% RH for 1 hour in accordance with JISZ-0237, and then subjected to a load of 100g in the shearing direction in an atmosphere of 100 ℃ to measure the offset distance of the adhesive tape after 24 hours. The measurement results are shown in the column "holding power" in the table.

[ evaluation method of bubble discharge easiness 1 (easiness of removal) ]

The release liner of the graphite composite sheet was peeled off, and an aluminum plate 200mm in length by 200mm in width was placed on the surface of the adhesive part at 23 ℃ under 50% RH, and the temporary adherend was left for 5 seconds in a state where a load of 10N was applied from above the aluminum plate.

Next, after the temporary pasted material was turned over, a 2kg roller was reciprocated once from the surface on the graphite composite sheet side to press them, thereby obtaining a laminate.

10 of the above laminates were produced by the above method. The presence of air bubbles between the adhesive layer of the graphite composite sheet constituting the laminate and the aluminum plate was confirmed by visually observing the swelling of the graphite sheet. The ease of discharging the air bubbles was evaluated based on the number of laminated bodies in which the presence of air bubbles could not be confirmed by the above method.

[ evaluation method of ease of bubble discharge 2 (ease of removal) ]

"PET 25X1J 0L" (release liner with a smooth release-treated surface, Ra 0.03 μm, manufactured by Nippa corporation) was attached to the surface of the adhesive portion formed by peeling the release liner of the graphite composite sheet, and the sheet was pressed under a linear pressure of 3N/mm using a laminator, and then left to stand at 23 ℃ for 1 day.

Then, the above "PET 25X1J 0L" was peeled off, and an aluminum plate 200mm in length × 200mm in width was placed on the surface of the adhesive portion formed by the peeling off at 23 ℃ and 50% RH, and the temporary adherend was left for 5 seconds in a state where a load of 10N was applied from above the aluminum plate.

10 of the above laminates were produced by the above method. The presence of air bubbles between the adhesion portion of the graphite composite sheet constituting the laminate and the aluminum sheet was confirmed by visually observing the swelling of the graphite sheet. The ease of discharging the air bubbles was evaluated based on the number of laminated bodies in which the presence of air bubbles could not be confirmed by the above method.

(presence/absence of lifting of the graphite composite sheet when peeling off the micro adhesive film)

A micro adhesive film (a PET film having a thickness of 75 μm and a silicone-based micro adhesive layer on one surface thereof: an adhesive force of 0.05N/20mm) was bonded to the surface of the single-sided adhesive tape "IL-05G" (manufactured by DIC corporation) constituting the graphite composite sheet, and the resulting laminate was placed on an aluminum plate and was adhered to the surface of the PET film by one reciprocating movement using a 2kg roller.

After 1 minute from the above-mentioned adhesion, the micro adhesive film was peeled off at a speed of 5m/min in a direction of 180 ° from the surface of the graphite composite sheet, and then it was visually evaluated whether or not the graphite composite sheet floated from the surface of the aluminum plate. The above test was performed by preparing 10 laminates from the graphite composite sheets obtained in examples and comparative examples. The number of laminates from which the graphite composite sheets could not be confirmed to float from the surface of the aluminum plate by the above test is shown in the following table.

(method of evaluating appearance)

The graphite composite sheet was attached to an aluminum plate, and the shape of the adhesive portion (the substantially rhombic shape, the substantially circular shape, and the like) was evaluated based on whether or not the adhesive portion was visible when the sheet was observed from a position 30cm away from the upper surface of the graphite composite sheet under a fluorescent lamp. A person who was not able to recognize the shape of the adhesion portion at all was evaluated as "excellent", a person who was slightly able to recognize the shape was evaluated as "o", and a person who was clearly able to recognize the shape was evaluated as "x". In the example in which the adhesive agent layer was formed by applying the adhesive agent to the entire surface of the support as in comparative example 1, the adhesive portion was not formed in a predetermined shape, and the shape thereof was not recognized by the above method, and was represented as "-" without evaluation.

[ number of adhered parts ]

The number of adhesive parts was determined as follows: the range of the adhesive tape (square of 5cm in the moving direction and 5cm in width) or (square of 1cm in the moving direction and 1cm in width) was observed with an electron microscope and counted.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

In the table, "substantially rhombic 1" means a rhombic adhesive part (fig. 1) having an angle of 60 ° at the corner facing the moving direction of the adhesive tape (an angle of 120 ° at the corner facing the width direction), "substantially rhombic 2" means a rhombic adhesive part having an angle of 30 ° at the corner facing the moving direction of the adhesive tape (an angle of 150 ° at the corner facing the width direction), "substantially square" means a square adhesive part having an angle of 90 ° at the corner facing the moving direction of the adhesive tape (an angle of 90 ° at the corner facing the width direction), "substantially circular" means an adhesive part having a shape shown in fig. 2, "substantially hexagonal (oblique line)" means an adhesive part having a shape shown in fig. 3, and "substantially quadrangular (oblique line)" means an adhesive part having a shape shown in fig. 4.

The adhesive tape of the embodiment has a plurality of independent adhesive agent layers on any one surface, and therefore has excellent bubble discharge easiness. On the other hand, in the adhesive tape of comparative example 1, since the adhesive layer was smooth, there was no passage for discharging bubbles, and the ease of discharging bubbles was remarkably poor. In the adhesive tapes of comparative examples 2 and 3, the adhesive layer has irregularities, and therefore, although the ease of initial bubble release is excellent, the ease of bubble release decreases over time after the release liner is attached.

Description of the symbols

1 support body

2 adhesive part

3 adhesive tape

4 graphite flake

5 Single-sided adhesive tape

6 double-sided adhesive tape

Claims

1. An adhesive tape having 2 or more adhesive parts (B) on at least one surface (a) side of a support (A), characterized in that a region having no adhesive part (B) is present between the 2 or more adhesive parts (B), the region being in communication with an end of the adhesive tape,

the peak temperature of the loss tangent of the adhesive part (B) based on a dynamic viscoelasticity spectrum measured at a frequency of 1Hz is-20 ℃ to 10 ℃.

2. The adhesive tape according to claim 1, wherein the shape of the adhesive portion (B) is substantially circular, substantially quadrangular, or substantially hexagonal when the adhesive portion (B) is viewed from the side of the one surface (a) of the support (a).

3. The adhesive tape according to claim 1 or 2, wherein a distance between any one of the 2 or more adhesive parts (B1) and the adhesive part (B2) close to the adhesive part (B1) is 0.5mm or less.

4. The adhesive tape according to claim 1 or 2, wherein the ratio of the area having the adhesive part (B) to the area of the one surface (a) of the support (a) is 10% to 99%.

5. The adhesive tape according to claim 1 or 2, wherein 120 to 2000 adhesive parts (B) are present in a range of 1cm in the moving direction and 1cm in the width direction of the adhesive tape.

6. The adhesive tape according to claim 1 or 2, having a total thickness of 20 μm or less.

7. The adhesive tape according to claim 1 or 2, having a 180 ° peel adhesion measured using a test piece obtained by: a smooth stainless steel plate was placed on the surface having the adhesive part (B), pressed by reciprocating once with a 2kg roller, and left at 23 ℃ and 50% RH for 1 hour.

8. The adhesive tape according to claim 1 or 2, which is used for bonding a heat generating member to a heat dissipating member or bonding a metal member in contact with the heat generating member to the heat dissipating member.

9. The adhesive tape of claim 8, wherein the heat dissipating member is a graphite sheet or a graphene sheet.

10. A heat sink sheet comprising a heat dissipating member and an adhesive tape according to any one of claims 1 to 8 bonded to one surface of the heat dissipating member and the other surface of the heat dissipating member.

11. An electronic device having a structure in which the heat sink according to claim 10 is attached to a heat generating member or a metal member in contact with the heat generating member, the electronic device comprising: the surface of the heat sink having the adhesive portion (B) is bonded to the heat generating member or the metal member.

12. A method for producing an adhesive tape according to any one of claims 1 to 8, wherein an adhesive is applied to at least one surface (a) of the support by a gravure coating method or a slot die coating method to form 2 or more adhesive parts (B) of a substantially circular shape, a substantially quadrangular shape or a substantially hexagonal shape,