JP2016155950A - Tacky-adhesive sheet, production method thereof, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin tacky-adhesive sheet which can prevent air bubbles from being left behind at the interface between the tacky-adhesive sheet and an adherend and which has excellent adhesive strength.SOLUTION: The tacky-adhesive sheet has a tacky adhesive layer on at least one surface side of a supporting body (A) and 20 μm or smaller total thickness. The tacky adhesive layer has 0.1-1.0 μm center line average surface roughness. The 180° peel adhesive strength is 3 N/20 mm or higher after 5 minutes have passed since the tacky-adhesive sheet is placed so that the tacky adhesive layer is contacted with the surface of a stainless steel plate and the tacky-adhesive sheet is press-fixed to the surface of the stainless steel plate. The 180° peel adhesive strength is 4 N/20 mm or higher after 60 minutes have passed since the tacky-adhesive sheet is press-fixed thereto.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thin pressure-sensitive adhesive sheet that can be suitably used, for example, in a case where a casing or a part of a portable electronic device is joined.

  The pressure-sensitive adhesive sheet is a joining means with excellent workability and high adhesion reliability, and is therefore widely used in the production scenes of electronic devices such as OA equipment and home appliances.

  In recent years, the electronic devices have been required to have high functionality, downsizing, and thinning, and in particular, portable electronic devices such as personal computers, digital video cameras, electronic notebooks, mobile phones, PHSs, smartphones, game devices, electronic books, and the like. Terminals are required to be further reduced in size and thickness. Therefore, in the manufacturing scene of the portable electronic terminal, the main component parts are made thinner, and the adhesive sheet used for fixing the parts is also required to be made thinner.

  As the thin adhesive sheet, for example, an adhesive sheet having an acrylic adhesive on both surfaces of the core material, the total thickness of the core material and the adhesive layer on both surfaces is 30 μm or less, A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer thickness of 2 to 10 μm is known (for example, see Patent Document 1).

  However, as the pressure-sensitive adhesive sheet is being made thinner, bubbles are likely to remain at the interface between the thin pressure-sensitive adhesive sheet and the adherend, resulting in swelling of the pressure-sensitive adhesive sheet. In some cases, the appearance may be poor, and the performance such as thermal conductivity and adhesive strength may be deteriorated.

  In particular, when the pressure-sensitive adhesive sheet is used for bonding a heat radiating member such as a graphite sheet and a heat generating member, the bubbles inhibit heat conduction from the heat generating member to the heat radiating member via the pressure sensitive adhesive sheet. There is. Therefore, it has been demanded that the pressure-sensitive adhesive sheet can be affixed without containing bubbles at the interface with the adherend.

As a method for suppressing the mixing of air bubbles when the pressure-sensitive adhesive sheet is adhered to the adherend, for example, a continuous groove is continuously formed on the pressure-sensitive adhesive surface up to the peripheral edge, and a plurality of independent island portions are formed. forming a further該独the area of Tatsuto portion from 0.25 mm ² and 8.41Mm ^2, the height of the independent island portion and 5 to 20 [mu] m, and, 0.1 mm to 0.5 mm the width of the extra fine grooves (For example, refer patent document 2).

  However, although the pressure-sensitive adhesive sheet is relatively thick, it can form complicated fine grooves as described above, but the thin-type pressure-sensitive adhesive sheet that can contribute to the thinning of the portable electronic device, etc. Forming a complicated groove or the like may be complicated in the production process.

  In addition, thin adhesive sheets with grooves or the like generally have a reduced contact area with the adherend due to the formation of the grooves, and the adhesive layer is thin. When the protective film is peeled off at high speed from the surface of the pressure-sensitive adhesive sheet or the graphite composite sheet obtained by using the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet or the graphite composite sheet is not lifted from the adherend. There was a case of causing peeling.

  Further, the thin adhesive sheet provided with the groove or the like is thin, and simply by using an adhesive layer having a groove part, from between the adhesive layer and the adherend, In some cases, fine bubbles are difficult to escape and still remain at their interfaces.

  In this way, even though it is thin, there is a demand for the development of a pressure-sensitive adhesive sheet that does not leave fine bubbles at the interface between the adherend and the pressure-sensitive adhesive layer, and has excellent adhesive strength. A pressure-sensitive adhesive sheet that has achieved both of these at a high level has not yet been found.

JP 2007-169327 A JP 2002-327157 A

  The problem to be solved by the present invention is to provide a thin pressure-sensitive adhesive sheet that can prevent bubbles from remaining at the interface with the adherend and has excellent adhesive strength.

  The present inventors have found that the above-described problems can be solved by using a pressure-sensitive adhesive sheet having a predetermined uneven shape on the surface of the pressure-sensitive adhesive layer that can come into contact with the adherend during pasting.

That is, the present invention is a pressure-sensitive adhesive sheet having a total thickness of 20 μm or less having a pressure-sensitive adhesive layer (B) directly or via another layer on at least one surface side of the support (A),
The pressure-sensitive adhesive layer (B) is a pressure-sensitive adhesive layer having a center line average surface roughness Ra in the range of 0.1 μm to 1.0 μm,
In an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, a test piece having a single-sided adhesive layer lined with a polyethylene terephthalate film is placed so that the adhesive layer (B) is in contact with the surface of a stainless steel plate (SUS plate). The adhesive strength (peeling speed 300 mm / min) is 3 N / 20 mm or more after 5 minutes from the time when they are placed and pressed once by reciprocating a 2 kg roller on the upper surface of the polyethylene terephthalate film. Further, the present invention relates to a pressure-sensitive adhesive sheet characterized by having a 180 ° peeling adhesive force (peeling speed 300 mm / min) 60 minutes after the pressure bonding is 4 N / 20 mm or more.

  The pressure-sensitive adhesive sheet of the present invention is very thin, hardly causes minute bubbles to remain at the interface with the adherend, and has excellent adhesive force. For example, the pressure-sensitive adhesive sheet includes a casing constituting an electronic device such as a portable electronic terminal. It can be suitably used for bonding with parts such as rechargeable batteries.

It is the schematic which shows an example of the adhesive sheet of this invention. It is a schematic process drawing which shows an example of the method of manufacturing the adhesive sheet of this invention. It is a schematic process drawing which shows an example of the method of manufacturing the adhesive sheet of this invention. It is a schematic process drawing which shows an example of the method of manufacturing the adhesive sheet of this invention. It is a schematic sectional drawing which shows an example of the graphite composite sheet obtained by bonding a single-sided adhesive sheet on one side of a graphite sheet, and a double-sided adhesive sheet on the other side. The surface of the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) constituting the pressure-sensitive adhesive sheet of Example 1 and the surface of the release liner attached to the pressure-sensitive adhesive layer were measured using a color 3D laser microscope. It is 3D bird's-eye view. It is the 3D bird's-eye view which measured the surface of the adhesive layer which comprises the adhesive sheet of the comparative example 1, and the surface of the peeling liner stuck on the said adhesive layer using the color 3D laser microscope. The surface of the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) constituting the pressure-sensitive adhesive sheet of Comparative Example 2 and the surface of the release liner attached to the pressure-sensitive adhesive layer were measured using a color 3D laser microscope. It is 3D bird's-eye view.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a total thickness of 20 μm or less having a pressure-sensitive adhesive layer (B) directly or via another layer on at least one surface side of the support (A),
The pressure-sensitive adhesive layer (B) is a pressure-sensitive adhesive layer having a center line average surface roughness Ra in the range of 0.1 μm to 1.0 μm,
In an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, a test piece having a single-sided adhesive layer lined with a polyethylene terephthalate film is placed so that the adhesive layer (B) is in contact with the surface of a stainless steel plate (SUS plate). The adhesive strength (peeling speed 300 mm / min) is 3 N / 20 mm or more after 5 minutes from the time when they are placed and pressed once by reciprocating a 2 kg roller on the upper surface of the polyethylene terephthalate film. The pressure-sensitive adhesive sheet is characterized by having a 180 ° peeling adhesion (peeling speed 300 mm / min) 60 minutes after the press-bonding is 4 N / 20 mm or more.

  As a specific embodiment of the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer (B) is directly laminated on both surfaces of the support (A), both sides of the support (A) are provided. On the surface, the pressure-sensitive adhesive layer (B) is laminated via the other layer, the pressure-sensitive adhesive layer (B) is directly laminated on the surface of one side of the support (A), And the surface of the one surface side of the said support body (A) by which the adhesive layer other than the said adhesive layer (B) was laminated | stacked on the surface of the other surface side directly or through another layer. In addition, the pressure-sensitive adhesive layer (B) is laminated via another layer, and the pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (B) is directly or via another layer on the surface of the other surface. Can be mentioned.

  As a specific embodiment of the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer (B) is laminated directly or via another layer on the surface of one surface of the support (A). A single-sided adhesive sheet.

  The pressure-sensitive adhesive layer (B) is a pressure-sensitive adhesive layer provided on at least one surface side of the support (A) and having a center line average surface roughness Ra of 0.1 μm to 1 μm. By using the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (B) on one side or both sides of the support (A), air bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive layer (B). As a result, it is possible to suppress poor appearance due to swelling of the pressure-sensitive adhesive sheet or the like, and performance degradation such as thermal conductivity and adhesive strength.

  The center line average surface roughness Ra of the pressure-sensitive adhesive layer (B) is suitably within the above range in the state where the release liner (C) is laminated on the surface of the pressure-sensitive adhesive layer (B). Further, the center line average surface roughness Ra of the pressure-sensitive adhesive layer (B) is determined by removing the release liner (C) from the surface of the pressure-sensitive adhesive layer (B) and then sticking the adherend to the surface. It is appropriate that it is retained for a period of time.

  By using the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (B), it is possible to prevent bubbles from remaining at the interface between the adherend and the pressure-sensitive adhesive layer (B). Adhesive strength can be expressed.

  As the pressure-sensitive adhesive layer (B), 180 ° peeling adhesion (peeling speed 300 mm / min) after 5 minutes from the time of pressure bonding to the surface of the adherend is 3 N / 20 mm or more, and the pressure bonding is performed. One having a 180 ° peeling adhesion (peeling speed 300 mm / min) 60 minutes after that is 4 N / 20 mm or more is used. Thereby, it is possible to prevent air bubbles from remaining at the interface between the adherend and the pressure-sensitive adhesive layer (B), and it is possible to express excellent adhesive force immediately after application. The pressure-sensitive adhesive layer (B) may have a centerline surface roughness Ra within the above range even after the pressure bonding. However, in order to quickly develop the strong adhesive strength within the above range after the pressure bonding. A pressure-sensitive adhesive layer having a center line surface roughness Ra outside the above range may be formed.

  As described above, the pressure-sensitive adhesive sheet of the present invention is peeled 180 ° after 5 minutes from the time when the pressure-sensitive adhesive layer (B) is in contact with the surface of the adherend and pressure-bonded them (peeling speed 300 mm / min). min) is 3 N / 20 mm or more, and the 180 ° peeling adhesive force (peeling speed 300 mm / min) after 60 minutes from the time when it is pressure-bonded to the surface of the adherend is 4 N / 20 mm or more.

  The 180 ° peel adhesion after 5 minutes is preferably in the range of 3.5 N / 20 mm to 15 N / 20 mm, more preferably in the range of 4.1 N / 20 mm to 10 N / 20 mm. It is easy to remove air bubbles from the interface between the adherend and the pressure-sensitive adhesive layer (B) even when the thickness is in the range of 5 N / 20 mm to 8 N / 20 mm, and excellent immediately after the pressure bonding. It is more preferable because it can exhibit adhesive strength.

  Further, the 180 ° peel adhesion after 60 minutes is preferably in the range of 4.3 N / 20 mm to 20 N / 20 mm, more preferably in the range of 4.5 N / 20 mm to 15 N / 20 mm, Even if the thickness is in the range of 5.0 N / 20 mm to 10 N / 20 mm, it is easy to remove bubbles from the interface between the adherend and the pressure-sensitive adhesive layer (B), and it has excellent adhesive force quickly. Is more preferable.

  In addition, the 180 degree peeling adhesive strength after 5 minutes of the pressure bonding refers to a value measured according to JISZ0237. Specifically, the 180 ° peel-off adhesive strength is 23 ° C. and relative humidity 50% RH. In the case of a double-sided PSA sheet, the adhesive layer on one side is lined with a 25 μm thick polyethylene terephthalate film. The test piece was placed so that the pressure-sensitive adhesive layer (B) was in contact with the surface of a clean and smooth stainless steel plate (SUS plate), and the 2 kg roller was reciprocated once on the upper surface of the polyethylene terephthalate film. Measured by peeling off the pressure-sensitive adhesive sheet at a peeling rate of 300 mm / min in the direction of 180 ° with respect to the pressure-bonding surface after being left for 5 minutes under conditions of 23 ° C. and 50% RH. Value.

  In addition, when using a double-sided adhesive sheet as an adhesive sheet of this invention, the said backing is performed with respect to the surface of the adhesive layer with the smooth surface, and it is on the adhesive layer (B) which is the structural requirements of this invention. This was not performed for the corresponding pressure-sensitive adhesive layer. Further, when the pressure-sensitive adhesive layer constituting the double-sided pressure-sensitive adhesive sheet corresponds to the pressure-sensitive adhesive layer (B) on both sides, it is lined against any one of the pressure-sensitive adhesive layers (B). Was used as a test piece.

  Moreover, when using a single-sided adhesive sheet as an adhesive sheet of this invention, what did not perform the said backing was used as the test piece.

  Further, the 180 ° peel adhesive strength after 60 minutes of pressure bonding refers to a value measured according to JISZ0237. Specifically, the 180 ° peel-off adhesive strength is 23 ° C. and relative humidity 50% RH. In the case of a double-sided PSA sheet, the adhesive layer on one side is lined with a 25 μm thick polyethylene terephthalate film. The test piece was placed so that the pressure-sensitive adhesive layer (B) was in contact with the surface of a clean and smooth stainless steel plate (SUS plate), and the 2 kg roller was reciprocated once on the upper surface of the polyethylene terephthalate film. Measured by peeling the pressure-sensitive adhesive sheet at a peeling rate of 300 mm / min in the direction of 180 ° with respect to the pressure-bonding surface after being left for 60 minutes under conditions of 23 ° C. and 50% RH. Value.

  In addition, when using a double-sided adhesive sheet as an adhesive sheet of this invention, the said backing is performed with respect to the surface of the adhesive layer with the smooth surface, and it is on the adhesive layer (B) which is the structural requirements of this invention. This was not performed for the corresponding pressure-sensitive adhesive layer. Further, when the pressure-sensitive adhesive layer constituting the double-sided pressure-sensitive adhesive sheet corresponds to the pressure-sensitive adhesive layer (B) on both sides, it is lined against any one of the pressure-sensitive adhesive layers (B). Was used as a test piece.

  Moreover, when using a single-sided adhesive sheet as an adhesive sheet of this invention, what did not perform the said backing was used as the test piece.

  The pressure-sensitive adhesive sheet of the present invention preferably has a total thickness of 20 μm or less, more preferably 1 μm to 15 μm, and more preferably 3 μm to 12 μm. It is more preferable to use one having a thickness of 3 μm to 7 μm, for example, in order to contribute to a reduction in thickness of a portable electronic terminal or the like. The total thickness of the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive measured by a method using a dial gauge according to JIS K6783 under the condition that the contact surface of the dial gauge is flat, the diameter is 5 mm, and the load is 1.23 N. It refers to the thickness of the sheet and does not include the thickness of the release liner. The thickness refers to a value measured using, for example, a thickness meter TH-102 manufactured by Tester Sangyo.

  As the pressure-sensitive adhesive sheet of the present invention, even if it is thin, it can be prevented from peeling off over time due to the repulsive force or the like of the adherend or the support (A) or the part falling off, and is used particularly at a relatively high temperature. In order to prevent the above peeling and the like, it is preferable to use one having an adhesive holding power of 2 mm or less, more preferably 0.5 mm or less, and 0.1 mm or less. It is more preferable to use what is.

  The adhesion holding force refers to a value measured according to JISZ0237. Specifically, the adhesion holding force is obtained by adhering a clean and smooth stainless steel plate (hairline) and an adhesive sheet obtained by lining one of the adhesive layers (B) with an aluminum foil having a thickness of 50 μm. The material layer (B) is laminated so that it adheres to the surface of the aluminum foil, and the top surface is pressed by reciprocating once using a 2 kg roller, and left for 1 hour at 23 ° C. and 50% RH. The test piece is used. Next, after the stainless steel plate constituting the test piece is fixed in a vertical direction in an environment of 100 ° C., and left for 24 hours in a state where a load of 100 g is applied to the lower end portion of the adhesive sheet constituting the test piece. This is a value obtained by measuring the displacement distance between the stainless steel plate and the adhesive sheet with calipers.

[Support (A)]
As the support (A) constituting the pressure-sensitive adhesive sheet of the present invention, one having a thickness of 1 μm to 4 μm is preferably used, and one having a thickness of 1.5 μm to 2.5 μm is preferably used. The sheet can be thinned, and air bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive layer (B). As a result, poor appearance due to swelling of the pressure-sensitive adhesive sheet, heat conduction, etc. It is more preferable because performance degradation such as property and adhesive strength can be prevented more effectively.

  As said support body (A), the sheet-like thing obtained using resin can be used, for example. Examples of the resin that can be used for the production of the support (A) include polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyamide (nylon), wholly aromatic polyamide ( Amide resins such as aramid), acrylic resins such as polybutyl acrylate, polyethyl acrylate, and polymethyl methacrylate (PMMA), polystyrene, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer ( ABS resin) and other styrenic resins, polyether ether ketone (PEEK), polyether ketone ketone and other polyether ketones, polyether sulfone (PES), polysulfone, polyvinyl chloride (PVC), polyethylene Phenylene sulfide (PPS), polyimide (PI), polyamideimide, polyetherimide (PEI), polyesterimide, polycarbonate (PC), polyacetal, polyarylene ether (polyphenylene ether, etc.), polyphenylene sulfide, polyarylate, polyaryl, polyurethane, An epoxy resin etc. can be used individually or in combination of 2 or more types.

  Among them, as the support (A), it is preferable to use a polyester film because there is little variation in thickness, excellent tensile strength and workability, and economical (cost), and a polyethylene terephthalate film is used. More preferably it is used. It is preferable to use a biaxially stretched polyester film because the strength of the support (A) and the pressure-sensitive adhesive sheet obtained using the support can be further increased.

  The said support body (A) can be manufactured by shape | molding above described resin in a sheet form. When using polyester as said resin, the said support body (A) can be manufactured with the following method, for example. First, a dry or undried polyester chip and, if necessary, a colorant or a masterbatch containing a colorant at a high concentration are melt-kneaded using a kneading extruder or the like.

  Next, the kneaded product is extruded from a die and rapidly cooled and solidified on a rotary cooling drum to obtain an unstretched polyester sheet that is substantially in an amorphous state.

  As a method for further improving the smoothness of the polyester sheet, for example, a method of shortening the residence time of the polyester in the extruder, when using a single screw extruder, the water content is preferably 50 ppm or less, more preferably When using a raw material such as polyester dried to be 30 ppm or less, or when using a twin screw extruder, a vent port is provided, preferably 40 hectopascals or less, more preferably 30 hectopascals or less, and even more preferably 20 Examples of the method include a method performed under a reduced pressure environment below hectopascal, and a method employing an electrostatic application adhesion method and a liquid application adhesion method, for example, in order to improve the adhesion between the polyester sheet and the rotary cooling drum.

  As a method of stretching the polyester sheet obtained by the above method, for example, the unstretched sheet is preferably stretched 2 to 6 times in the longitudinal direction at 70 ° C. to 145 ° C., longitudinally uniaxially stretched, and then laterally oriented. The film is stretched 2 to 6 times at 90 ° C to 160 ° C, and the heat setting step is started.

  The polyester sheet is preferably relaxed by 0.1% to 20% in the machine direction and / or the transverse direction in the maximum temperature zone for heat treatment and / or the cooling zone at the heat treatment outlet. The stretched polyester sheet obtained by the above method may be relonged and restretched as necessary.

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

  Moreover, as said support body (A), in order to further improve the adhesiveness etc. with the said adhesive layer (B), on one side or both surfaces, for example, chromic acid treatment, ozone exposure treatment, flame exposure treatment Those having been subjected to an oxidation treatment such as high-piezoelectric exposure treatment or ionizing radiation treatment, and those having a primer layer formed by using a coating agent or the like can be used.

[Adhesive layer (B)]
Next, the adhesive layer (B) which comprises the adhesive sheet of this invention is demonstrated.

  The pressure-sensitive adhesive layer (B) is provided on at least one surface side of the support (A) directly or via another layer. That is, the said adhesive layer (B) may be provided in the both surfaces side of a support body (A), and may be provided only in the one surface side of a support body (A).

  As the pressure-sensitive adhesive layer (B), a pressure-sensitive adhesive layer having a center line average surface roughness Ra of 0.1 μm to 1 μm is used.

  The pressure-sensitive adhesive layer (B) has a center line average surface roughness Ra in the range of 0.1 μm to 1 μm. Here, the said surface refers to the surface of the adhesive layer (B) which can contact the surface of a to-be-adhered body in the case of bonding. When the pressure-sensitive adhesive layer (B) having the predetermined centerline average surface roughness is bonded to the surface of the adherend, bubbles that may remain at the interface between the adherend and the pressure-sensitive adhesive layer (B) It is easy to come off in the pressure-bonding process, and a very high level of adhesive force is developed immediately after the pressure-bonding process.

  The center line average surface roughness Ra of the pressure-sensitive adhesive layer (B) is more preferably 0.15 μm to 0.8 μm, more preferably 0.2 μm to 0.7 μm, and 0.3 μm to 1 0.0 μm can easily remove air bubbles from the interface between the adherend and the pressure-sensitive adhesive layer (B). As a result, poor appearance due to swelling of the pressure-sensitive adhesive sheet, thermal conductivity, etc. It is more preferable because it can more effectively prevent performance degradation such as heat resistance and adhesive strength.

  The ten-point average surface roughness Rz of the pressure-sensitive adhesive layer (B) is not particularly limited, but Rz is preferably 2 μm to 20 μm, more preferably 3 μm to 15 μm, and more preferably 4 μm. 10 to 10 μm, air bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive layer (B). As a result, poor appearance due to swelling of the pressure-sensitive adhesive sheet, thermal conductivity, etc. Further, it is more preferable because performance degradation such as heat resistance and adhesive strength can be more effectively prevented.

  The surface roughness such as the center line average surface roughness Ra and the ten-point average surface roughness Rz refers to a value measured using a non-contact type surface roughness measuring instrument using a confocal laser. Specifically, the above-mentioned centerline average surface roughness Ra and ten-point average surface roughness Rz are the values specified in JISB0601, and a “color 3D laser microscope / scanner using a violet laser (408 nm) as a laser light source”. Using VK-9500 "(manufactured by KEYENCE), the adhesive layer (B) two minutes after the release liner (C) was peeled, at any three locations (in the range of 50 μm in length × 50 μm in width each) It is an average value of values obtained by measuring the surface roughness.

  As described above, the center line average surface roughness Ra and the ten-point average surface roughness Rz of the pressure-sensitive adhesive layer (B) are as described above in a state where the release liner (C) is laminated on the surface of the pressure-sensitive adhesive layer (B). It is appropriate to be within the range. Further, as described above, the center line average surface roughness Ra and the ten-point average surface roughness Rz of the pressure-sensitive adhesive layer (B) are obtained after removing the release liner (C) from the surface of the pressure-sensitive adhesive layer (B). It is appropriate that the substrate is held for a period until the adherend is pasted on the surface.

  By using the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (B), it is possible to prevent air bubbles from remaining at the interface between the adherend and the pressure-sensitive adhesive layer (B), and to provide excellent adhesive strength after application. Can be expressed.

  The peak temperature of the loss tangent based on the dynamic viscoelastic spectrum measured at a frequency of 1 Hz of the pressure-sensitive adhesive layer (B) is not particularly limited, but is preferably −40 ° C. to 15 ° C., It is more preferably −20 ° C. to 10 ° C., and it is −10 ° C. to 5 ° C. that the surface shape represented by the center line average surface roughness Ra of the pressure-sensitive adhesive layer (B) is easily maintained. Therefore, it is easy to prevent changes over time such as surface roughness, and air bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive layer (B), resulting in swelling of the pressure-sensitive adhesive sheet. It is more preferable because it can more effectively prevent poor appearance and performance deterioration such as thermal conductivity, heat resistance and adhesive strength.

  In the dynamic viscoelasticity measurement, a viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD) is used, and a test piece is sandwiched between parallel disks which are measurement units of the tester and stored at a frequency of 1 Hz. An elastic modulus (G ′) and a loss elastic modulus (G ″) are measured. The loss tangent is calculated by an expression represented by tan δ = (G ″) / (G ′). The peak temperature refers to the peak temperature confirmed by the spectrum of tan δ with respect to the measurement temperature region (−50 ° C. to 150 ° C.).

  As the test piece, an adhesive layer having a thickness of 0.5 mm to 2.5 mm can be used. Moreover, as said test piece, the thing whose total thickness of an adhesive layer is 0.5 mm-2.5 mm among what laminated | stacked the adhesive sheet of this invention in multiple numbers can be used. When the test piece having the different configuration is used, the value of the tan δ changes, but when the total thickness of the pressure-sensitive adhesive layer (B) in the test piece is the same, the peak temperature is substantially It does not change. Therefore, any test piece may be used in the measurement of the peak temperature.

  As said adhesive layer (B), it is preferable to use what has a gel fraction of 5 mass%-55 mass%, and it is preferable to use what has a gel fraction of 10 mass%-50 mass%. More preferably, the use of a material having a gel fraction of 15% by mass to 50% by mass, even if it is thin, has fine bubbles that tend to remain at the interface between the adherend and the pressure-sensitive adhesive layer (B). It is preferable because it can be easily removed and can exhibit an excellent adhesive force immediately after being attached to an adherend.

  In addition, the said gel fraction points out the value measured by the method shown below.

  The release liner (C) having a release treatment surface coated with the pressure-sensitive adhesive so that the thickness after drying becomes 50 μm is dried in an environment of 100 ° C. for 3 minutes, and then an environment of 40 ° C. A pressure-sensitive adhesive layer was formed by aging under for 2 days.

  A test piece was prepared by cutting the pressure-sensitive adhesive layer into a square of 50 mm length and 50 mm width.

  After measuring the mass (G1) of the test piece, the test piece was immersed in toluene for 24 hours in an environment of 23 ° C.

  After the immersion, the mixture of the test piece and toluene was filtered using a 300 mesh wire net to extract insoluble components in toluene. The mass (G2) of the insoluble component dried at 110 ° C. for 1 hour was measured.

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

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

  As the pressure-sensitive adhesive layer (B), those having a thickness of 0.5 μm to 6 μm are preferably used, and those having a thickness of 1 μm to 3 μm are preferably used. It is more preferable when obtaining an adhesive sheet. In particular, the pressure-sensitive adhesive layer (B) preferably has a thickness of 1 μm to 6 μm, and a thickness of 1 μm to 3 μm is preferably used at the interface between the adherend and the pressure-sensitive adhesive layer (B). It is more preferable because air bubbles can be easily removed from the surface, and as a result, poor appearance due to swelling of the pressure-sensitive adhesive sheet and performance deterioration such as thermal conductivity, heat resistance and adhesive force can be more effectively prevented. . In addition, as for the said adhesive layer (B), each adhesive layer provided in each surface of the said support body (A) may have the same thickness, and it has a different thickness. Also good. The thickness of the pressure-sensitive adhesive layer (B) is measured by a method using a dial gauge in accordance with JIS K6783 under the condition that the contact surface of the dial gauge is flat, the diameter thereof is 5 mm, and the load is 1.23N. Refers to the thickness of the double-sided PSA sheet.

  The pressure-sensitive adhesive layer (B) is, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a styrene-diene block copolymer-based pressure-sensitive adhesive, or a vinyl alkyl ether-based pressure-sensitive adhesive. It can be formed using a known pressure-sensitive adhesive such as an adhesive, a polyamide-based pressure-sensitive adhesive, a fluorine-based pressure-sensitive adhesive, a creep property improving pressure-sensitive adhesive, and a radiation curable pressure-sensitive adhesive. Among these, as the pressure-sensitive adhesive layer (B), it is preferable to use a pressure-sensitive adhesive layer obtained using an acrylic pressure-sensitive adhesive because of excellent adhesion reliability. The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet of the present invention may be the same composition or gel fraction, etc., on both sides of the pressure-sensitive adhesive layer, and is a pressure-sensitive adhesive layer having a different composition or gel fraction. Also good.

  As said acrylic adhesive, what contains an acrylic polymer can be used.

  As said acrylic polymer, what is obtained by polymerizing the monomer component containing (meth) acryl monomers, such as a (meth) acrylic-acid alkylester, can be used.

  Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-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, (meth) acrylic acid Undecyl, dodecyl (meth) acrylate, tridecyl (meth) acrylate, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate alone Or two or more types can be combined. Especially, as a (meth) acrylic-acid alkylester, it is preferable to use the (meth) acrylic-acid alkylester whose carbon atom number of the said alkyl group is 1-20, and the carbon atom number of the said alkyl group is 4-18. It is more preferable to use (meth) acrylic acid alkyl ester. Examples of the alkyl group include linear or branched alkyl groups.

  As the (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms for the acrylic group, butyl (meth) acrylate is likely to remain at the interface between the adherend and the pressure-sensitive adhesive layer (B). Even minute bubbles can be easily removed, and an excellent adhesive force can be quickly expressed after being attached to an adherend, which is preferable.

  As the (meth) acrylic monomer, in addition to those described above, a monomer having a carboxyl group such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, or the anhydride thereof A monomer having a sulfonic acid group such as sodium vinyl sulfonate; a monomer having a cyano group such as acrylonitrile; an amide group such as acrylamide, methacrylamide, N-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide; A monomer having a hydroxyl group such as hydroxyalkyl (meth) acrylate and glycerin dimethacrylate; a monomer having an amino group such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; Imido groups such as cyclohexylmaleimide and isopropylmaleimide Monomers having an epoxy group such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; Monomers 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, tri Use monomers such as methylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, etc. alone or in combination of two or more. It can be.

  In addition to the (meth) acrylic monomer, the monomer includes aromatic vinyl compounds such as styrene and substituted styrene; olefins such as ethylene, propylene, and butadiene; vinyl esters such as vinyl acetate; Vinyl chloride or the like can also be used.

  The acrylic polymer can be produced by polymerizing the monomer by a method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method, and a solution polymerization method may be employed. It is preferable for improving the production efficiency of the acrylic polymer.

  Examples of the solution polymerization method include a method of radical polymerization by mixing and stirring the monomer, a polymerization initiator, and an organic solvent, preferably at a temperature of 40 ° C. to 90 ° C.

  Examples of the polymerization initiator include peroxides such as benzoyl peroxide and lauryl peroxide, azo thermal polymerization initiators such as azobisisobutylnitrile, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, benzyl A ketal photopolymerization initiator, an acyl phosphine oxide photopolymerization initiator, a benzoin photopolymerization initiator, a benzophenone photopolymerization initiator, or the like can be used.

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

  As the acrylic polymer obtained by the above method, those having a weight average molecular weight of 300,000 to 1,200,000 are preferably used, and those having a weight average molecular weight of 400,000 to 1,100,000 are more preferably used. It is preferable to use a material having a weight average molecular weight of 500,000 to 1,000,000 in order to obtain a pressure-sensitive adhesive sheet having even better adhesive force and ease of removing bubbles even if it is thin.

  The weight average molecular weight is a value measured by gel permeation chromatography (GPC method) and calculated in terms of 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 volume: 100 μl
Eluent: Tetrahydrofuran Flow rate: 1.0 ml / min Measuring temperature: 40 ° C
This column: TSKgel GMHHR-H (20) 2 Guard column: TSKgel HXL-H
Detector: Differential refractometer Weight average molecular weight of standard polystyrene: 10,000 to 20 million (manufactured by Tosoh Corporation)

  The pressure-sensitive adhesive that can be used for forming the pressure-sensitive adhesive layer (B) includes a tackifier resin for forming a pressure-sensitive adhesive layer having more excellent adhesive strength, tensile strength, and tensile breaking strength. It is preferable to use it.

  Examples of the tackifying resin include a rosin tackifying resin, a polymerized rosin tackifying resin, a polymerized rosin ester tackifying resin, a rosin phenol tackifying resin, a stabilized rosin ester tackifying resin, and a disproportionated rosin ester. It is possible to use petroleum resin-based tackifiers such as styrene-based tackifier resins, hydrogenated rosin ester-based tackifier resins, terpene-based tackifier resins, terpene phenol-based tackifier resins, and styrene-based tackifier resins.

  As the tackifying resin, a combination of a rosin-based tackifying resin and a petroleum resin-based tackifying resin is used, and the pressure-sensitive adhesive sheet has an even better adhesive force and ease of removing bubbles. Is preferable in obtaining. The rosin-based tackifying resin and petroleum resin-based tackifying resin are preferably used in combination with the acrylic polymer, and an acrylic polymer obtained by polymerizing a monomer containing butyl (meth) acrylate. It is preferable to use in combination in order to obtain a pressure-sensitive adhesive sheet having even better adhesive strength and ease of air bubble removal even if it is thin.

  Moreover, as the tackifying resin, it is preferable to use a tackifying resin that is liquid at room temperature in order to further improve the initial adhesive force of the pressure-sensitive adhesive layer (B). Examples of the tackifying resin that is liquid at room temperature include low-molecular-weight liquid rubbers such as process oil, polyester plasticizer, and polybutene, and terpene phenol resins can be used. Commercially available YP manufactured by Yashara Chemical Co., Ltd. -90L etc. are mentioned.

  The tackifying resin is preferably used in the range of 20 to 60 parts by mass, more preferably in the range of 30 to 55 parts by mass, with respect to 100 parts by mass of the acrylic polymer. It is more preferable for obtaining a pressure-sensitive adhesive sheet having high adhesive strength.

  Moreover, as an adhesive which comprises the said adhesive layer (B), a softener, a plasticizer, a filler, an anti-aging agent, a coloring agent etc. are contained as needed other than the said acrylic polymer. Things can be used.

  Especially, use of a crosslinking agent can adjust the gel fraction of the said adhesive layer (B) to the above-mentioned suitable range, As a result, an adherend and an adhesive layer (B) It is preferable because a microbubble that tends to remain at the interface can be easily removed, and a pressure-sensitive adhesive sheet can be obtained that can express excellent adhesive force immediately after being attached to an adherend.

  As the crosslinking agent, it is preferable to use, for example, an isocyanate-based crosslinking agent or an epoxy crosslinking agent.

  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 toluene diisocyanate adduct such as trimethylolpropane-modified tolylene diisocyanate. The toluene diisocyanate adduct has a structure derived from toluene diisocyanate in the molecule, and examples of commercially available products include Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.).

  When using the said isocyanate type crosslinking agent, it is preferable to use the acrylic polymer which has a hydroxyl group as said acrylic polymer. The acrylic polymer having a hydroxyl group is, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate as a monomer used for the production thereof. It is more preferable to use 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

  Moreover, as an epoxy crosslinking agent, for example, Tetrad X and Tetrad C manufactured by Mitsubishi Gas Chemical Co., Ltd., or E-05X manufactured by Soken Chemical Co., Ltd. can be used.

  When using the said epoxy type crosslinking agent, it is preferable to use the acrylic polymer which has an acid group as said acrylic polymer. The acrylic polymer having an acid group may use, for example, (meth) acrylic acid, acrylic acid dimer, itaconic acid, crotonic acid, maleic acid, maleic anhydride, etc. as a monomer used for the production thereof. Preferably, (meth) acrylic acid is used.

[Method for producing adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention uses, for example, a pressure-sensitive adhesive exemplified as usable for forming the pressure-sensitive adhesive layer (B) on at least one surface of the support (A) by a conventionally known method. Step [1] of producing a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (B ′) having a line average surface roughness Ra of 0 μm to 0.2 μm, and a release treatment surface on the surface of the pressure-sensitive adhesive layer (B ′) It can manufacture by passing through process [2] which sticks the release liner (C) whose centerline average surface roughness Ra is 0.1 micrometer-3 micrometers.

  As the step [1], for example, the pressure-sensitive adhesive layer (B ′) is formed on one surface of the support (A) by applying the pressure-sensitive adhesive and drying, and then the support (A ) Is applied to the other surface and dried to form a pressure-sensitive adhesive layer (B ′) to produce a pressure-sensitive adhesive sheet.

  Moreover, as said process [1], the process which forms an adhesive layer (B ') by apply | coating an adhesive continuously on both surfaces of the said support body (A), drying etc., and manufacturing an adhesive sheet is included. Can be mentioned.

  Moreover, as said process [1], after forming the adhesive layer (B '), for example by apply | coating the said adhesive to the surface of a release liner and drying etc., the said adhesive layer is used for a support body (A). A process for producing a pressure-sensitive adhesive sheet by transferring to one or both sides is preferable (see FIGS. 2 and 3).

  A specific manufacturing method will be described with reference to FIGS. 2 and 3. The pressure-sensitive adhesive sheet is obtained by applying a pressure-sensitive adhesive to the release treatment surface of the release liner 11 using the coating apparatus 12 and drying the pressure-sensitive adhesive. The step of producing a release liner with a layer (1), the support 14 and the release liner with a pressure-sensitive adhesive layer (1) are laminated by a laminate roll 15, whereby the pressure-sensitive adhesive layer is transferred to one side of the support. The step of manufacturing the single-sided pressure-sensitive adhesive sheet 16, the same or different pressure-sensitive adhesive as described above is applied to the release treatment surface of the release liner 17 different from the above by using the coating device 12 and dried. The step of producing the release liner with layer (2), the single-sided pressure-sensitive adhesive sheet obtained above, and the release liner with pressure-sensitive adhesive layer (2) are laminated by the laminating roll 15, thereby the support. A process for producing a double-sided pressure-sensitive adhesive sheet by transferring the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive layer-attached release liner (2) to the surface (the surface not having the pressure-sensitive adhesive layer transferred by the pressure-sensitive adhesive layer-release liner (1)). It can manufacture by going through.

  In that case, when the release liner forms the pressure-sensitive adhesive layer (B ′) having the center line average surface roughness Ra in the range of 0 μm to 0.2 μm, the center line average surface roughness Ra of the release treatment surface is obtained. It is preferable to use a release liner having a thickness of 0 μm to 0.2 μm.

  In the transfer step of the pressure-sensitive adhesive layer (B ′) to the support (A), the support (A) and the release liner with pressure-sensitive adhesive layer (1), or the single-sided pressure-sensitive adhesive sheet and release liner with pressure-sensitive adhesive layer Conventionally, heating (2) to 40 ° C. to 80 ° C. in a laminated state results in a thin adhesive layer (B ′) having a surface shape of the support (A) (for example, a fine uneven shape). It is preferable because it is easy to follow.

  The release liners 11 and 17, the support 14, the single-sided pressure-sensitive adhesive tape 16, and the pressure-sensitive adhesive sheet 18 that can be used when manufacturing the pressure-sensitive adhesive sheet may be respectively fed out from a roll or wound into a roll.

  The pressure-sensitive adhesive layer (B ′) possessed by the pressure-sensitive adhesive sheet obtained in the step [1] is 5% by mass to 55% by mass in order to quickly exhibit excellent adhesive force when being pressure-bonded to the adherend. It is preferable to use those having a gel fraction of 10% by mass to 50% by mass, more preferably those having a gel fraction of 15% by mass to 50% by mass. More preferably, is used. In addition, the gel fraction of the said adhesive layer (B ') is a measurement of the gel fraction of the said adhesive layer (B) except having used the adhesive sheet which has an adhesive layer (B') as a test piece. The value measured by the method similar to the method described as a method is pointed out.

  The step [2] of forming the pressure-sensitive adhesive layer (B) by applying the predetermined surface roughness Ra to at least one surface of the pressure-sensitive adhesive layer (B ′) of the pressure-sensitive adhesive sheet includes, for example, the step The release liner is removed from the pressure-sensitive adhesive sheet obtained in [1], and the release liner has a center line average surface roughness Ra of 0.1 to 3 μm on the surface of the pressure-sensitive adhesive layer (B ′). A step of attaching (C) is mentioned (see FIG. 4).

  As the release liner (C), for example, it is preferable to use a release treatment surface having a center line average surface roughness Ra of 0.1 μm to 2.0 μm, preferably 0.2 μm to 1.0 μm. In order to obtain a pressure-sensitive adhesive sheet having a higher level of both excellent ease of air bubble removal and excellent adhesion, it is more preferable to use a material having a thickness of 0.3 μm to 0.8 μm. Further preferred.

  When the release liner (C) is affixed, the pressure-sensitive adhesive layer (B ′) may already have a certain degree of cross-linking reaction and have a gel fraction in the above range. In that case, when forming the adhesive layer (B) in the range of the center line average surface roughness Ra 0.1 μm to 1.0 μm, the center line average surface larger than the center line average surface roughness of the adhesive layer (B). It is preferable to use a release liner having a release treatment surface having a roughness because an adhesive layer (B) having a center line average surface roughness Ra in the range of 0.1 μm to 1.0 μm is easily formed.

  As the release liner containing the release liner (C), for example, a film obtained by forming a resin such as polyethylene terephthalate, polyethylene, polypropylene, ethylene-propylene copolymer into a film, foamed film, Japanese paper, paper, Paper such as glassine paper, non-woven fabric, metal foil, and a film obtained by combining and laminating them can be used. It is preferable to use a film obtained by using a resin, and a film containing polyethylene terephthalate is used. Is more preferable.

  As the release liner (C) used when forming the pressure-sensitive adhesive layer (B), a sand mat film obtained by sandblasting the surface of the various films described above, a mixture of the resin and the mat material is used. A film obtained by molding into a film can be used.

  Moreover, as said release liner (C), it is preferable to use the thing with the peeling force with respect to the said adhesive layer (B) of the range of 0.01N / 20mm-1N / 20mm, 0.01N / 20mm-0 It is more preferable to use one having a range of 1 N / 20 mm, and it is preferable to use one having a thickness of 0.01 N / 20 mm to 0.06 N / 20 mm when the release liner (C) is peeled off. It is preferable for controlling the change in the surface roughness of (B).

  In addition, the said peeling force points out the value measured with the following method. A test piece is prepared by backing a pressure-sensitive adhesive layer on one side of the pressure-sensitive adhesive sheet with a polyethylene terephthalate film having a thickness of 50 μm. Measured by peeling the release liner (C) from the surface of the pressure-sensitive adhesive layer (B) of the test piece at a speed of 0.3 m / min in the direction of 180 ° with respect to the surface direction of the release liner (C). To do.

  The said peeling force can be adjusted by changing suitably the kind etc. of the mold release processing agent known as what can be used for formation of a mold release process surface.

  As the mold release treatment agent, for example, a silicone release treatment agent, a fluorine release treatment agent, an investigation alkyl release treatment agent, or the like can be used. The mold release treatment agent can be used, for example, by coating the surface of a film such as the sand mat film.

  As an embodiment of the pressure-sensitive adhesive sheet of the present invention, as described above, the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (B) having a predetermined surface roughness or the like on both sides of the support (A), the support (A). It has a pressure-sensitive adhesive layer (B) having a predetermined surface roughness, etc. on one surface side, and the surface roughness, etc. is not specified on the other surface side, for example, a surface-smooth pressure-sensitive adhesive layer is formed And a single-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (B) having a predetermined surface roughness on one surface side of the support (A).

  For example, when producing a pressure-sensitive adhesive sheet having a substantially smooth pressure-sensitive adhesive layer (for example, a pressure-sensitive adhesive layer (B ′) having a center line average surface roughness Ra in the range of 0 μm to 0.2 μm), the surface thereof When forming a smooth pressure-sensitive adhesive layer, a release liner having a smooth release treatment surface can be used. The release liner is made of the same material as the release liner (C) exemplified as being usable when the pressure-sensitive adhesive layer (B) is manufactured, except for the surface roughness of the release treatment surface. Can be used. More specifically, examples of the release liner include those that do not include the mat material and those that are not subjected to sandblasting.

  The pressure-sensitive adhesive sheet obtained by the above method can be stored or transported in a state of being wound in a roll, for example. When winding in the roll shape, the pressure-sensitive adhesive sheet is preferably 5 m or more, more preferably 10 m or more, and more preferably 20 m or more.

Even if the pressure-sensitive adhesive sheet of the present invention is very thin, minute bubbles are easily removed from the interface between the pressure-sensitive adhesive layer (B) and the adherend, and promptly after being pressure-bonded to the adherend. Excellent adhesion can be expressed. When the pressure-sensitive adhesive layer (B) of the pressure-sensitive adhesive sheet is stuck to the surface of the adherend, since it has the predetermined center line surface roughness Ra, air bubbles can easily escape from the interface during the pressure bonding. . On the other hand, after the pressure-sensitive adhesive sheet and the adherend are pressure-bonded, the pressure-sensitive adhesive layer (B) is in a state before a surface state having a predetermined centerline surface roughness Ra is applied (specifically, Since the force to return to the state of the pressure-sensitive adhesive layer (B ′) works, the pressure-sensitive adhesive layer and the adherend easily adhere to the surface, and as a result, after being pressure-bonded to the adherend, it is excellent quickly. Therefore, the pressure-sensitive adhesive sheet of the present invention can be suitably used in the production scene of electronic devices such as portable electronic terminals that are required to be thin. In particular, the adherend can be firmly bonded even when the clearance between the adherends (adhesive portion of the adhesive sheet) is in a very narrow range having a width of 20 μm or less.

  In addition, since the pressure-sensitive adhesive sheet is easy to remove air bubbles from the interface between the adherend and the adhesive layer (B), the heat-dissipating sheet is used for fixing, and the magnetic sheet may be deteriorated in performance due to the residual air bubbles. It can be suitably used for fixing applications.

(Use for fixing heat dissipation sheet)
Many electronic devices such as portable electronic terminals are equipped with a member that generates heat when used. Examples of the heat generating member include a rechargeable battery and a circuit board.

  It is preferable to avoid a part of the electronic device from being locally heated due to the heat generated by the member in order to prevent malfunction of the electronic device. Therefore, the heat-generating member or a member adjacent to the heat-generating member (for example, a metal member that is a frame material used for imparting rigidity to the electronic device) is radiated by a heat-dissipating sheet or the like for the purpose of diffusing the heat. Members are often affixed.

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

  Examples of the graphite sheet include two types: an artificial graphite sheet and a natural graphite sheet.

  Examples of the artificial graphite sheet include a pyrolytic graphite sheet obtained by pyrolyzing an organic film such as a polyimide film in a high-temperature inert gas atmosphere.

  Examples of the natural graphite sheet include those obtained by acid-treating natural graphite and then pressurizing and expanding the graphite powder heated and expanded.

  As the graphite sheet, it is preferable to use a sheet having less wrinkles from the standpoint of further improving heat dissipation, and it is more preferable to use an artificial graphite sheet having less wrinkles.

  The thickness of the graphite sheet is preferably 10 μm to 100 μm, and more preferably 15 μm to 50 μm, in order to contribute to thinning of electronic devices such as portable electronic terminals.

  On the other hand, since the graphite sheet is relatively brittle, it is generally used in the form of a graphite composite sheet having an adhesive sheet attached to one or both sides thereof.

  As the graphite composite sheet, for example, as shown in FIG. 5, it is possible to use a graphite composite sheet having a structure sealed with a single-sided adhesive tape and a double-sided adhesive sheet. It is preferable to achieve both.

  As the graphite composite sheet, it is possible to prevent the occurrence of interlaminar breakage or powder falling of the graphite sheet by using what is sealed (pouched) by an adhesive sheet having a larger area than the graphite sheet, This is preferable because it is easy to realize suitable workability.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used when pouching the graphite sheet. In that case, it is preferable to use the said adhesive sheet in the state in which the adhesive layer (B) faces an outer side direction (direction which is not a graphite sheet side). Thereby, when bonding a graphite composite sheet and heat generating members, such as a rechargeable battery, or a member adjacent to it, it can prevent effectively that air bubbles remain in those interfaces.

  The bonding of the graphite composite sheet and the member is performed, for example, by placing the graphite composite sheet on the surface of the member and temporarily bonding them by lightly pressing them, after the temporary bonding, using a roller or the like. It can be carried out through a step of pressing and firmly bonding them. In the temporary adhering step, bubbles are usually present at the interface between the member and the graphite composite sheet. However, in the case of a graphite composite sheet using the pressure-sensitive adhesive sheet of the present invention, the bubbles are quickly removed from the interface when pressed 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 scratches on the surface thereof. The surface protective film is usually removed after attaching the graphite composite sheet and the member.

  If the pressure-sensitive adhesive sheet of the present invention is used, it is possible to firmly adhere to an adherend such as a member after the bubbles are removed. Therefore, when removing the surface protective film from the graphite composite sheet, the member of the graphite composite sheet Difficult to cause floating or peeling off.

  As described above, the graphite composite sheet obtained using the pressure-sensitive adhesive sheet of the present invention can prevent the presence of bubbles at the interface with the adherend such as a member. Therefore, the thermal resistance of the pressure-sensitive adhesive sheet due to the presence of the bubbles. An increase in value can be effectively prevented, and as a result, the thermal conductivity in the thickness direction of the pressure-sensitive adhesive sheet can be improved.

  The electronic device having a structure in which the heat generating member and the heat radiating member or the metal member in contact with the heat generating member and the heat radiating member are bonded together by the adhesive sheet can effectively diffuse the heat from the heat generating member. Difficult to cause malfunctions such as malfunctions due to influences.

(Use for fixing magnetic sheets)
The magnetic sheet is used to block the leakage of electromagnetic waves emitted from the members constituting the electronic device to the outside, and to prevent the electromagnetic waves generated outside from affecting the electronic device. It is often affixed to.

  Examples of the magnetic sheet include 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- Sheets obtained using Ni alloy powder, Fe-Co alloy powder, Fe-Si-Al alloy powder, Fe-Si-Cr alloy powder, iron powder, Fe-based amorphous, Co-based amorphous, Fe-based nanocrystals, etc. Can be used.

  In general, it is preferable to use a relatively thick sheet as the magnetic sheet in order to impart good electromagnetic wave shielding characteristics.

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

  The magnetic sheet is preferably used in the form of a magnetic composite sheet in which an adhesive sheet is attached on one or both sides for the purpose of imparting good insulation and high strength.

  Examples of the present invention will be described below in more detail.

(Preparation Example 1) Adhesive A
N-butyl acrylate 97.98 parts by mass, acrylic acid 2 parts by mass, 4-hydroxybutyl acrylate 0.02 parts by mass, azobisisobutyronitrile 0.2 part by mass as a polymerization initiator, ethyl acetate By carrying out solution polymerization at 80 ° C. for 8 hours in the solution, an acrylic polymer having a weight average molecular weight of 900,000 was obtained.

  5 parts by mass of “D-135” (Arakawa Chemical Industries, Ltd., polymerized rosin ester) and “KE-100” (Arakawa Chemical Industries, Ltd., disproportionate) with respect to 100 parts by mass of the acrylic polymer. 20 parts by mass of rosin ester) and 25 parts by mass of “FTR6100” (manufactured by Mitsui Chemicals, Inc., petroleum resin) are mixed, and further an ethyl acetate is added to obtain an adhesive solution adjusted to a solid content of 40% by mass. It was.

  Adhesive A was obtained by mixing and stirring the adhesive solution and 2.0 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate-based crosslinking agent).

  The peak temperature of tan δ of the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive A was 0 ° C., and the gel fraction thereof was 40% by mass.

(Preparation Example 2) Adhesive B
Ethyl acetate using 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.3 parts by mass of azobisisobutyronitrile as a polymerization initiator An acrylic polymer having a weight average molecular weight of 500,000 was obtained by solution polymerization in a solution at 90 ° C. for 6 hours.

  5 parts by mass of “D-135” (produced by Arakawa Chemical Industries, Ltd., polymerized rosin ester) and “KE-100” (produced by Arakawa Chemical Industries, Ltd., disproportionated rosin with respect to 100 parts by mass of the acrylic polymer. Ester) 20 parts by mass and “FTR6100” (manufactured by Mitsui Chemicals, petroleum resin) 25 parts by mass were mixed, and further an ethyl acetate was added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass. .

  Adhesive B was obtained by mixing and stirring the adhesive solution and 0.6 part by mass of “NC40” (manufactured by DIC Corporation, isocyanate-based crosslinking agent).

  The peak temperature of tan δ of the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive B was 0 ° C., and the gel fraction thereof was 10% by mass.

(Preparation Example 3) Adhesive C
Ethyl acetate using 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.3 parts by mass of azobisisobutyronitrile as a polymerization initiator An acrylic polymer having a weight average molecular weight of 500,000 was obtained by solution polymerization in a solution at 90 ° C. for 6 hours.

  With respect to 100 parts by mass of the acrylic polymer, 5 parts by mass of “D-135” (polymerized rosin ester, manufactured by Arakawa Chemical Co., Ltd.) and “KE-100” (manufactured by Arakawa Chemical Industries, Ltd., disproportionated rosin) Ester) 20 parts by mass and “FTR6100” (manufactured by Mitsui Chemicals, petroleum resin) 25 parts by mass were mixed, and further an ethyl acetate was added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass. .

  Adhesive C was obtained by mixing and stirring the adhesive solution and 3.3 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate-based crosslinking agent).

  The peak temperature of tan δ of the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive C was 0 ° C., and the gel fraction thereof was 46% by mass.

(Preparation Example 4) Adhesive D
96.4 parts by mass of n-butyl acrylate, 3.5 parts by mass of acrylic acid, 0.1 part by mass of 4-hydroxy-ethyl acrylate, 0.2 part by mass of azobisisobutyronitrile as a polymerization initiator Then, an acrylic polymer having a weight average molecular weight of 800,000 was obtained by solution polymerization in an ethyl acetate solution at 80 ° C. for 8 hours.

  10 parts by weight of “D-135” (produced by Arakawa Chemical Co., Ltd., polymerized rosin ester) and 100 parts by mass of the acrylic polymer, and “A100” (disproportionated rosin ester, produced by Arakawa Chemical Industries, Ltd.) A pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass was obtained by mixing 10 parts by mass and further adding ethyl acetate.

  The pressure-sensitive adhesive D was obtained by mixing and stirring the pressure-sensitive adhesive solution and 1.3 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate-based crosslinking agent).

  The peak temperature of tan δ of the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive D was −15 ° C., and the gel fraction thereof was 40% by mass.

(Preparation Example 5) Adhesive E
44.9 parts by mass of n-butyl acrylate, 50 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of vinyl acetate, 2 parts by mass of acrylic acid, and 0.1 part by mass of 4-hydroxybutyl acrylate were mixed with azobisiso An acrylic polymer having a weight average molecular weight of 800,000 was obtained by performing solution polymerization at 70 ° C. for 10 hours in an ethyl acetate solution using 0.1 part by mass of butyronitrile as a polymerization initiator.

  10 parts by weight of “D-135” (manufactured by Arakawa Chemical Industries, Ltd., polymerized rosin ester) is mixed with 100 parts by weight of the acrylic polymer, and the solid content is adjusted to 40% by weight by adding ethyl acetate. An adhesive solution was obtained.

  Adhesive E was obtained by mixing and stirring the adhesive solution and 1.3 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate-based crosslinking agent).

  The peak temperature of tan δ of the pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive E was −25 ° C., and the gel fraction thereof was 40% by mass.

Example 1
Using a roll coater, the pressure-sensitive adhesive A is applied to “PET25X1J0L” (manufactured by Nipper Co., Ltd., release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm). After coating, a pressure-sensitive adhesive layer having a thickness of 2 μm was produced by drying at 100 ° C. for 1 minute.

  Next, the pressure-sensitive adhesive layer was transferred to one surface of “K100-2.0W” (Mitsubishi Resin Co., Ltd., polyester film, thickness 2 μm) as a support.

  Next, rolls to “PET25X1J0” (manufactured by Lintec Corporation, release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm of the release treatment surface) The pressure-sensitive adhesive A was applied using a coater and then dried at 100 ° C. for 1 minute to prepare a pressure-sensitive adhesive layer having a thickness of 2 μm.

  Next, the pressure-sensitive adhesive layer was transferred to the other surface of the support to obtain a pressure-sensitive adhesive sheet having a total thickness of 6 μm.

  After the adhesive sheet was cured for 120 hours in an environment of 23 ° C., the “PET25X1J0L” was peeled off, and “PET50X1MC-J0” (manufactured by Nipper Co., Ltd., surface of a sand mat-treated PET film) was removed on the surface of the adhesive layer A release liner having a silicone release treatment surface, centerline average surface roughness Ra = 0.52 μm) was affixed, and a 2 kg roller was reciprocated once on the upper surface, followed by curing in an environment of 23 ° C. for 24 hours. The pressure of the laminator used when transferring the pressure-sensitive adhesive layer to the support was set to a linear pressure of 3 N / mm.

  The release liner “PET50X1MC-J0” (manufactured by Nipper Co., Ltd., release liner having a silicone release treatment surface on the surface of a PET film subjected to sand mat treatment, centerline average surface roughness Ra = 0.52 μm) FIG. 6 (1) shows a 3D bird's-eye view showing the surface state in a range of 300 μm in length × 200 μm in width obtained by measuring the peeling treatment surface to be measured using “Color 3D Laser Microscope / VK-9500” manufactured by KEYENCE. . Moreover, the surface of the said adhesive layer of the range of the length of 300 micrometers x 200 micrometers obtained by measuring the surface of the adhesive layer obtained by peeling the said release liner "PET50X1MC-J0" by the method similar to the above A 3D bird's-eye view showing the state is shown in FIG. Note that the 3D bird's-eye view is displayed with the Z-axis enlarged three times.

(Example 2)
Instead of “PET50X1MC-J0” (manufactured by Nipper Co., Ltd.), “PSM100GS” (manufactured by Lintec Co., Ltd., release liner having a silicone-based release treatment surface on the surface of a sand-matted PET film, centerline average surface roughness A pressure-sensitive adhesive sheet (total thickness 6 μm) was obtained in the same manner as in Example 1 except that the thickness Ra = 0.36 μm was used.

(Example 3)
Instead of “PET50X1MC-J0” (manufactured by Nippa Corporation), “PLMF25GS” (manufactured by Lintec Corporation), release liner having a silicone-based release treatment surface on the surface of a PET film in which a mat material is kneaded, centerline average A pressure-sensitive adhesive sheet (total thickness: 6 μm) was obtained in the same manner as in Example 1 except that the surface roughness Ra = 0.21 μm was used.

Example 4
An adhesive sheet (total thickness: 6 μm) was obtained in the same manner as in Example 1 except that the adhesive B was used in place of the adhesive A.

(Example 5)
An adhesive sheet (total thickness: 6 μm) was obtained in the same manner as in Example 1 except that the adhesive C was used instead of the adhesive A.

(Example 6)
An adhesive sheet (total thickness: 6 μm) was obtained in the same manner as in Example 1 except that the adhesive D was used in place of the adhesive A.

(Example 7)
A pressure-sensitive adhesive sheet (total thickness 6 μm) was obtained in the same manner as in Example 1 except that pressure-sensitive adhesive E was used instead of pressure-sensitive adhesive A.

(Example 8)
A pressure-sensitive adhesive sheet (total thickness: 6 μm) was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive was changed to 4 μm instead of 2 μm.

(Comparative Example 1)
Using a roll coater, the pressure-sensitive adhesive A is applied to “PET25X1J0L” (manufactured by Nipper Co., Ltd., release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm). After coating, a pressure-sensitive adhesive layer having a thickness of 2 μm was produced by drying at 100 ° C. for 1 minute.

  Next, the pressure-sensitive adhesive layer was transferred to one surface of “K100-2.0W” (Mitsubishi Resin Co., Ltd., polyester film, thickness 2 μm) as a support.

  Next, rolls to “PET25X1J0” (manufactured by Lintec Corporation, release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm of the release treatment surface) The pressure-sensitive adhesive A was applied using a coater and then dried at 100 ° C. for 1 minute to prepare a pressure-sensitive adhesive layer having a thickness of 2 μm. Next, the pressure-sensitive adhesive layer was transferred to the other surface of the support to obtain a pressure-sensitive adhesive sheet having a total thickness of 6 μm.

  The pressure of the laminator used when transferring the pressure-sensitive adhesive layer to the support was set to a linear pressure of 3 N / mm.

  The release liner “PET25X1J0” (manufactured by Lintec Corporation, release liner having a silicone release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm of the release treatment surface) FIG. 7 (1) shows a 3D bird's-eye view showing the surface state in the range of 300 μm in length × 200 μm in width obtained by measuring the peeling surface to be formed using “Color 3D Laser Microscope / VK-9500” manufactured by KEYENCE. Show. In addition, the surface state of the pressure-sensitive adhesive layer in the range of 300 μm in length × 200 μm in width obtained by measuring the surface of the pressure-sensitive adhesive layer obtained by peeling the release liner “PET25X1J0” in the same manner as described above. The 3D bird's-eye view shown is shown in FIG. Note that the 3D bird's-eye view is displayed with the Z-axis enlarged three times.

(Comparative Example 2)
Using a roll coater, the pressure-sensitive adhesive A is applied to “PET25X1J0L” (manufactured by Nipper Co., Ltd., release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm). After coating, a pressure-sensitive adhesive layer having a thickness of 2 μm was produced by drying at 100 ° C. for 1 minute.

  Next, the pressure-sensitive adhesive layer was transferred to one surface of “K100-2.0W” (Mitsubishi Resin Co., Ltd., polyester film, thickness 2 μm) as a support.

  Next, a roll coater is used for “PSM100GS” (manufactured by Lintec Corporation, a release liner having a silicone-based release treatment surface on the surface of a PET film that has been sand-matted, centerline average surface roughness Ra = 0.36 μm). After applying the pressure-sensitive adhesive A, the pressure-sensitive adhesive layer having a thickness of 2 μm was prepared by drying at 100 ° C. for 1 minute. Next, the pressure-sensitive adhesive layer was transferred to the other surface of the support to obtain a pressure-sensitive adhesive sheet having a total thickness of 6 μm.

  The pressure of the laminator used when transferring the pressure-sensitive adhesive layer to the support was set to a linear pressure of 3 N / mm.

  Note that the release liner “PSM100GS” (produced by Lintec Corporation, a release liner having a silicone-type release treatment surface on the surface of a sand-matted PET film, centerline average surface roughness Ra = 0.36 μm) FIG. 8 (1) shows a 3D bird's-eye view showing the surface state in the range of 300 μm in length × 200 μm in width obtained by measuring the treated surface using “Color 3D Laser Microscope / VK-9500” manufactured by KEYENCE. In addition, the surface state of the pressure-sensitive adhesive layer in the range of 300 μm in length × 200 μm in width obtained by measuring the surface of the pressure-sensitive adhesive layer obtained by peeling the release liner “PSM100GS” in the same manner as described above. The 3D bird's-eye view shown is shown in FIG. Note that the 3D bird's-eye view is displayed with the Z-axis enlarged three times.

(Comparative Example 3)
Using a roll coater, the pressure-sensitive adhesive A is applied to “PET25X1J0L” (manufactured by Nipper Co., Ltd., release liner having a silicone-based release treatment surface on the surface of a smooth PET film, centerline average surface roughness Ra = 0.03 μm). After coating, a pressure-sensitive adhesive layer having a thickness of 2 μm was produced by drying at 100 ° C. for 1 minute.

  Next, the pressure-sensitive adhesive layer was transferred to one surface of “K100-2.0W” (Mitsubishi Resin Co., Ltd., polyester film, thickness 2 μm) as a support.

  Next, a roll coater is applied to “PLMF25GS” (manufactured by Lintec Corporation, a release liner having a silicone-type release treatment surface on the surface of a PET film kneaded with a mat material, centerline average surface roughness Ra = 0.21 μm). After coating the pressure-sensitive adhesive A using a film, the pressure-sensitive adhesive layer having a thickness of 2 μm was prepared by drying at 100 ° C. for 1 minute. Next, the pressure-sensitive adhesive layer was transferred to the other surface of the support to obtain a pressure-sensitive adhesive sheet having a total thickness of 6 μm.

  The pressure of the laminator used when transferring the pressure-sensitive adhesive layer to the support was set to a linear pressure of 3 N / mm.

(Measurement method of center line average surface roughness Ra and ten-point average surface roughness Rz of the pressure-sensitive adhesive layer)
The pressure-sensitive adhesive sheets obtained in the above Examples and Comparative Examples were cured for 2 days in an environment of 40 ° C.

  From the pressure-sensitive adhesive sheet after curing, a pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) constituting the present invention (any pressure-sensitive adhesive layer in Comparative Example 1, or a predetermined centerline surface in Comparative Examples 2 and 3) The release liner laminated on the side of the pressure-sensitive adhesive layer having a rough uneven surface was peeled in the direction of 180 ° with respect to the surface of the release liner at a speed of 300 mm / min. Two minutes after the peeling, the center line average surface roughness Ra and ten-point average surface roughness Rz of the surface of the pressure-sensitive adhesive layer were measured by the following methods.

  “Color 3D laser microscope / VK-9500” manufactured by KEYENCE (lens magnification 50 ×, measurement mode: ultra-depth, pitch: 0) for any three locations on the surface of the pressure-sensitive adhesive layer (each in a range of 50 μm × 50 μm square) .05 μm, optical zoom: 1.0 times), and the center line average surface roughness Ra and ten-point average surface roughness Rz were measured. The average value of the three-point centerline average surface roughness Ra obtained by the measurement is defined as the centerline average surface roughness of the pressure-sensitive adhesive layer, and the average value of the three-point average surface roughness Rz is determined as the pressure-sensitive adhesive layer. The ten-point average surface roughness Rz.

(Method for measuring the gel fraction of the adhesive layer)
The pressure-sensitive adhesives A to E are each coated on the surface of a polyethylene terephthalate film (S25) having a thickness of 25 μm so as to have a dry thickness of 30 μm, and dried to form a pressure-sensitive adhesive layer. It was cured for 2 days in an environment of ℃.

  The pressure-sensitive adhesive layer after curing was immersed in toluene at room temperature and left for 24 hours.

  Based on the mass of the pressure-sensitive adhesive layer before being immersed in the toluene and the mass of the pressure-sensitive adhesive layer remaining in the toluene after the standing, the gel fraction was calculated by the following formula.

  Gel fraction = [(mass of adhesive layer remaining in toluene) / (mass of adhesive layer before being immersed in toluene)] × 100

(Measurement of dynamic viscoelasticity)
A pressure-sensitive adhesive layer is formed by coating the pressure-sensitive adhesives A to E on the surface of a polyethylene terephthalate film (S25, manufactured by Unitika Co., Ltd.) having a thickness of 25 μm so as to have a dry thickness of 50 μm. It was cured for 2 days in an environment of ℃. A test piece was prepared by laminating the adhesive layer after curing until the total thickness was 2 mm.

  Next, using a viscoelasticity tester (trade name: Ares 2KSTD, manufactured by Rheometrix Co., Ltd.), the test piece was sandwiched between parallel disk-shaped measuring parts having a diameter of 7.9 mm, a frequency of 1 Hz, and a heating time of 1 ° C./1. The storage elastic modulus (G ′) and loss elastic modulus (G ″) from −50 ° C. to 150 ° C. were measured under the condition of min. The loss tangent tan δ was calculated from the following calculation formula.

  Loss tangent tan δ = G ″ / G ′

(180 ° peel adhesion after 5 minutes after crimping)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a width of 20 mm, and a test piece was prepared by backing the pressure-sensitive adhesive layer on one side with a polyethylene terephthalate film having a thickness of 25 μm. The backing is performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, and is not performed on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) which is a constituent of the present invention.

  Of the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) (any pressure-sensitive adhesive layer in Comparative Example 1, and pressure-sensitive adhesive layer having an uneven surface with a predetermined centerline surface roughness in Comparative Examples 2 and 3) Immediately after removing the release liner from the surface, it was affixed to the surface of a clean and smooth stainless steel plate, and the upper surface was pressurized by reciprocating once using a 2 kg roller at 23 ° C. according to JISZ-0237. And 50% RH for 5 minutes.

  After the standing, peel adhesive strength (peeling direction: 180 °, peeling speed: 300 mm / min) was measured using a Tensilon tensile tester in an atmosphere of 23 ° C. and 50% RH.

(180 ° peel adhesion after 60 minutes of crimping)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a width of 20 mm, and a test piece was prepared by backing the pressure-sensitive adhesive layer on one side with a polyethylene terephthalate film having a thickness of 25 μm. The backing is performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, and is not performed on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) which is a constituent of the present invention.

  Of the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) (any pressure-sensitive adhesive layer in Comparative Example 1, and pressure-sensitive adhesive layer having an uneven surface with a predetermined centerline surface roughness in Comparative Examples 2 and 3) Immediately after removing the release liner from the surface, it was affixed to the surface of a clean and smooth stainless steel plate, and the upper surface was pressurized by reciprocating once using a 2 kg roller at 23 ° C. according to JISZ-0237. And 50 minutes RH for 60 minutes.

  After the standing, peel adhesive strength (peeling direction: 180 °, peeling speed: 300 mm / min) was measured using a Tensilon tensile tester in an atmosphere of 23 ° C. and 50% RH.

(Peeling force)
After the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut to a width of 20 mm, the release liner laminated on the side not corresponding to the pressure-sensitive adhesive layer (B) constituting the present invention was peeled off, and a polyethylene terephthalate having a thickness of 25 μm A test piece was backed with a film.

  According to JISZ-0237, the test piece was left for 1 hour under conditions of 23 ° C. and 50% RH, and then the other pressure-sensitive adhesive layer using a Tensilon tensile tester in an atmosphere of 23 ° C. and 50% RH. (Pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) which is a constituent of the present invention. In Comparative Example 1, any pressure-sensitive adhesive layer, and in Comparative Examples 2 and 3, an uneven surface having a predetermined centerline surface roughness. The release force when the release liner on the side of the pressure-sensitive adhesive layer) was peeled off under conditions of a peeling direction of 180 ° and a peeling speed of 300 m / min was measured.

(Production of graphite composite sheet)
A single-sided adhesive tape “IL-05G” (manufactured by DIC Corporation) having a length of 104 mm × width of 104 mm × thickness of 5 μm is bonded to one surface of a graphite sheet having a length of 100 mm × width of 100 mm × thickness of 25 μm. On the other surface, the adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 104 mm long × 104 mm wide, and bonded together.

  At that time, among the pressure-sensitive adhesive layers constituting the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer having a smooth surface was in contact with the graphite sheet.

  Next, a fine composite single-sided tape “CPF50 (25) -SP” (manufactured by Nipper Co., Ltd.) having a thickness of 62 μm was bonded to the surface of the single-sided adhesive tape “IL-05G” to obtain a graphite composite sheet. .

[Evaluation Method for Ease of Bubble Removal 1 (Ease of Removal)]
After peeling the release liner from the graphite composite sheet and leaving it in an atmosphere of 23 ° C. and 50% RH for 2 minutes, an aluminum plate measuring 200 mm in length and 200 mm in width is placed on the surface of the pressure-sensitive adhesive layer, and 10 N is placed on the aluminum plate. A temporary patch was obtained by leaving it under load for 5 seconds.

  Next, after reversing the temporary patch, a laminate was obtained by pressing them by reciprocating a 2 kg roller from the surface of the graphite composite sheet side.

  Ten laminates were produced by the above method. Whether or not bubbles exist between the pressure-sensitive 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 bubble removal was evaluated based on the number of laminates for which the presence of bubbles could not be confirmed by the above method.

[Evaluation Method for Ease of Bubble Removal 2 (Ease of Removal)]
The pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive layer (B) of the pressure-sensitive adhesive sheet of 50 mm × 50 mm (in the comparative example 1, any pressure-sensitive adhesive layer, and in the comparative examples 2 and 3, an uneven surface having a predetermined center line surface roughness) The release liner is peeled off from the surface of the pressure-sensitive adhesive layer), left in an atmosphere of 23 ° C. and 50% RH for 2 minutes, a glass plate is placed on the surface of the pressure-sensitive adhesive layer, and a 2 kg roller is reciprocated once on the upper surface. After crimping them, they were left for 24 hours. Whether or not minute bubbles of a size that cannot be visually confirmed remain at the interface between the glass plate and the pressure-sensitive adhesive layer was observed using a digital microscope KH-7700 manufactured by HIROOX, magnified 250 times. As a result of the above observation, when a bubble having a minute size that was not visually confirmed (a bubble having a diameter of about 10 μm) was not confirmed, it was evaluated as “◯”, and a bubble having the minute size was confirmed as “ “×”.

(Evaluation method of adhesive strength of adhesive sheet)
[Whether or not the graphite composite sheet floats when the slightly adhesive film is peeled off]
On the surface of the single-sided adhesive tape “IL-05G” (manufactured by DIC Corporation) constituting the graphite composite sheet, a fine-adhesive film (one having a silicone-based fine-adhesive layer on one side of a 75 μm-thick PET film: clean and smooth A stainless steel plate was applied to the surface, and the upper surface was pressed by reciprocating once using a 2 kg roller. The laminated product in which the adhesive strength measured in (1) = 0.05 N / 20 mm) was placed on an aluminum plate, and the surface was pasted once by reciprocating the surface with a 2 kg roller.

  1 minute after the sticking, whether or not the graphite composite sheet floats off the surface of the aluminum plate after peeling the fine adhesive film at a speed of 10 m / min in the direction of 180 ° with respect to the surface of the graphite composite sheet Was visually evaluated. Ten laminates were produced for each of the graphite composite sheets obtained in Examples, Comparative Examples, and Reference Examples, and the above test was performed. The number of laminates for which the graphite composite sheet was not lifted from the surface of the aluminum plate by the above test is shown in the table below.

  "Replacing" in Tables 1 to 3 indicates that the adhesive tape is manufactured through a process of replacing the release liner, and "direct coating" is manufactured without performing a process of replacing the release liner. Represents an adhesive tape.

  Even if the pressure-sensitive adhesive sheet of the example and the graphite composite sheet obtained using the same are very thin films, large bubbles are likely to escape from the interface with the adherend, and immediately after being pressure-bonded to the adherend, Excellent adhesion was developed. In addition, the pressure-sensitive adhesive sheet of the example was easy to remove very small bubbles, and was optimal for fixing a graphite sheet composite sheet. Moreover, even if it peeled off at a high speed when peeling off the said slightly adhesive film, the said adhesive sheet is hard to produce a crack and peeling, Therefore It could be used suitably for the fixation use of a graphite composite sheet. On the other hand, the tape of Comparative Example 1 and the graphite composite sheet obtained using the tape were not sufficient in terms of sticking workability because large bubbles were difficult to escape from the interface with the adherend. In the pressure-sensitive adhesive sheets of Comparative Examples 2 and 3 and the graphite composite sheet obtained using the same, small bubbles were likely to remain, although large bubbles were easily removed. Further, when the slightly adhesive film was peeled off from the surface of the graphite composite sheet at high speed, a float was generated at the interface between the graphite composite sheet and the adherend.

DESCRIPTION OF SYMBOLS 1 Support body 2, 3 Adhesive layer 4 Release liner whose centerline average surface roughness Ra of a mold release process surface is 0.1 micrometer-3 micrometers 5, 11, 17 Release liner 12 Adhesive coating apparatus 13 Drying apparatus 14 Support Body 15 Laminate roll 16 Single-sided adhesive sheet 18 Adhesive sheet 19 Adhesive sheet of the present invention 20 Graphite composite sheet 21 Single-sided adhesive tape 22 Double-sided adhesive sheet

Claims (13)

A pressure-sensitive adhesive sheet having a total thickness of 20 μm or less having a pressure-sensitive adhesive layer (B) directly or via another layer on at least one surface side of the support (A),
The pressure-sensitive adhesive layer (B) is a pressure-sensitive adhesive layer having a center line average surface roughness Ra in the range of 0.1 μm to 1.0 μm,
In an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, a test piece having a single-sided adhesive layer lined with a polyethylene terephthalate film is placed so that the adhesive layer (B) is in contact with the surface of a stainless steel plate (SUS plate). The adhesive strength (peeling speed 300 mm / min) is 3 N / 20 mm or more after 5 minutes from the time when they are placed and pressed once by reciprocating a 2 kg roller on the upper surface of the polyethylene terephthalate film. The pressure-sensitive adhesive sheet is characterized by having a 180 ° peeling adhesive force (peeling speed 300 mm / min) 60 minutes after the press-bonding is 4 N / 20 mm or more. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer (B) has a ten-point average surface roughness Rz of 2 μm to 20 μm. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the support (A) has a thickness of 1 μm to 4 μm, and the pressure-sensitive adhesive layer (B) has a thickness of 1 μm to 6 μm. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer (B) has a gel fraction of 5 mass% to 55 mass%. The peak temperature of the loss tangent based on the dynamic viscoelasticity spectrum measured at a frequency of 1 Hz of the pressure-sensitive adhesive layer (B) is in the range of -40 ° C to 15 ° C. The adhesive sheet as described. A pressure-sensitive adhesive sheet used for bonding a heat generating member and a heat radiating member, or a metal member contacting a heat generating member and a heat radiating member, wherein the pressure-sensitive adhesive layer (B) is attached to the heat generating member or the metal member. It is an adhesive layer stuck, The adhesive sheet of any one of Claims 1-5. The pressure-sensitive adhesive sheet according to claim 6, wherein the heat dissipation member is a graphite sheet or a graphene sheet. A pressure-sensitive adhesive sheet having a release liner (C) laminated on the surface of the pressure-sensitive adhesive layer (B), the center of the release treatment surface of the release liner (C) laminated on the surface of the pressure-sensitive adhesive layer (B) The pressure-sensitive adhesive sheet according to claim 1, wherein the line average surface roughness Ra is 0.1 μm to 3 μm. The peeling force when the release liner (C) is peeled from the surface of the pressure-sensitive adhesive layer (B) in the 180 ° direction at a speed of 0.3 m / min is 0.01 N / 20 mm to 1 N / 20 mm. The pressure-sensitive adhesive sheet described in 1. Step [1] of producing a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (B ′) having a center line average surface roughness Ra in the range of 0 μm to 0.2 μm, and the surface of the pressure-sensitive adhesive layer (B ′), At least one surface of the support (A), comprising a step [2] of applying a release liner (C) having a centerline average surface roughness Ra of 0.1 to 3 μm of the release treatment surface A method for producing a pressure-sensitive adhesive sheet having a total thickness of 20 μm or less having the pressure-sensitive adhesive layer (B) directly on the side or via another layer. The manufacturing method of the adhesive sheet of Claim 10 whose gel fraction of the said adhesive layer (B ') is 5 mass%-55 mass%. The electronic device having a structure in which the heat generating member and the heat radiating member, or the metal member in contact with the heat generating member and the heat radiating member are bonded together by the pressure sensitive adhesive sheet according to claim 1, The electronic device, wherein the pressure-sensitive adhesive layer (B) constituting the sheet is a pressure-sensitive adhesive layer on the side attached to the heat generating member or the metal member. The electronic device according to claim 12, wherein the metal member is a frame material used to give rigidity to the electronic device.

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