JP2013053294A - Connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure using a double-sided adhesive sheet which is excellent in thermal conductivity and also in handleability.SOLUTION: The double-sided adhesive sheet 1 used in the connection structure includes: a base material 2; a first adhesive layer 3 laminated on one surface 2a of the base material 2; and a second adhesive layer 4 laminated on the other surface 2b of the base material. The base material 2 has an elastic modulus of 50 to 300 GPa at 25°C, a thermal conductivity of 100 W/m×K or more, and an average thickness of 10 to 200 μm. The first and second adhesive layers 3, 4 each contain aluminum having thermal conductivity of 5 W/m×K or more. The first and second adhesive layers 3, 4 each have a filler content of 20 to 60 vol% in 100 vol% of each layer 3, 4. The average thicknesses of the first and second adhesive layers 3, 4 are each 20 to 200 μm.

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer laminated on both surfaces of the base material, and more particularly to a double-sided pressure-sensitive adhesive sheet excellent in thermal conductivity and handleability. Moreover, this invention relates to the connection structure using the said double-sided adhesive sheet.

  In an electronic device and a communication device, members constituting the electronic device and the communication device may be bonded together using a double-sided pressure-sensitive adhesive sheet. For example, an electronic component and a heat sink are bonded together using a double-sided adhesive sheet. Further, in the liquid crystal display device, members constituting the liquid crystal display device are bonded together using a double-sided pressure-sensitive adhesive sheet.

  The liquid crystal display device includes a liquid crystal panel, a drive circuit (driver IC) disposed around the liquid crystal panel, and a backlight attached to the back side of the liquid crystal panel.

  Conventionally, cold cathode fluorescent lamps have been widely used as the light source of the backlight, but in recent years, LEDs with low power consumption have been widely used.

  The LED is generally mounted on a laminate of an aluminum plate, an insulating layer, and a copper foil. This laminate is called CCL. The CCL is cut into an elongated plate having a width of several millimeters, and then an LED is mounted on the cut CCL to form an LED substrate. When the backlight housing and the LED substrate are fixed, screwing has been generally used, but in recent years, a double-sided pressure-sensitive adhesive sheet may be used to improve workability. In this case, first, one surface of the double-sided pressure-sensitive adhesive sheet is attached to the back surface of the LED substrate. Next, the LED substrate is fixed to the backlight casing by pressing the other surface of the double-sided pressure-sensitive adhesive sheet against the backlight casing.

  As an example of the double-sided pressure-sensitive adhesive sheet, the following Patent Document 1 discloses a soft metal layer, a rubber layer laminated on one side or both sides of the soft metal layer, and a pressure-sensitive adhesive covering the surface of at least one rubber layer. A double-sided PSA sheet having an agent is disclosed. The rubber layer preferably contains hydrophobized magnesium oxide.

  In the following Patent Document 2, an acrylic ester resin having a weight average molecular weight of 500,000 to 1,500,000 measured as a polystyrene-equivalent molecular weight by the GPC method, an alcoholic hydroxyl group, and a softening point of 140 to 170 ° C. A double-sided pressure-sensitive adhesive sheet comprising a tackifier resin and a terpene phenol resin and having a gel fraction of 5 to 40% by weight and laminated and integrated on both surfaces of a substrate is disclosed. Has been.

JP-A-11-204705 JP 2010-65095 A

  In recent years, miniaturization and high performance of electric devices and communication devices have been advanced. For this reason, in the said electronic device and communication apparatus, the mounting density of an electronic component is high. Along with this, a large amount of heat is easily generated from the electronic components, and the need to dissipate the generated heat is increasing. In order to dissipate heat, a double-sided pressure-sensitive adhesive sheet that bonds members such as electronic components needs to have high thermal conductivity.

  In particular, in the above-described LED backlight, as the liquid crystal display device such as a liquid crystal television becomes larger and thinner, higher output and higher density are progressing. This is because it is effective to arrange the backlight in the peripheral part of the liquid crystal display device for thinning the liquid crystal television, but the length of the peripheral part is proportional to the half power of the area. This is because it is necessary to increase the number of outputs and the number of implementations. When the temperature of the LED increases, the light emission efficiency decreases and the lifetime decreases. For this reason, in order to dissipate the heat generated from the LED efficiently, the double-sided pressure-sensitive adhesive sheet that joins the LED substrate and the backlight housing is also required to have high thermal conductivity.

  However, the thermal conductivity of the conventional double-sided PSA sheet as described in Patent Documents 1 and 2 may be relatively low, and it may be difficult to sufficiently dissipate the generated heat.

  Furthermore, the conventional double-sided pressure-sensitive adhesive sheet may be bent unintentionally. For example, when mounting a double-sided pressure-sensitive adhesive sheet having a release liner laminated on both sides to an LED substrate, the release liner laminated on one adhesive layer is peeled off, the LED substrate is attached, and then the other release liner When peeling off, the double-sided PSA sheet may peel off from the LED substrate and bend.

  An object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet having excellent thermal conductivity and excellent handleability. A limited object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet that can suppress a decrease in adhesion between the double-sided pressure-sensitive adhesive sheet and an object to be bonded when an impact is applied at the time of use or after dropping. That is.

  Moreover, the objective of this invention is providing the connection structure using the double-sided adhesive sheet which is excellent in heat conductivity and is excellent in the handleability. A limited object of the present invention is to use a double-sided pressure-sensitive adhesive sheet that can suppress a decrease in adhesion between the double-sided pressure-sensitive adhesive sheet and the object to be bonded when an impact is applied after use or when dropped. It is to provide a connection structure.

  According to a wide aspect of the present invention, a base material, a first pressure-sensitive adhesive layer laminated on one surface of the base material, and a second pressure-sensitive adhesive layer laminated on the other surface of the base material, The substrate has an elastic modulus at 25 ° C. of 50 GPa or more and 300 GPa or less, a thermal conductivity of 100 W / m · K or more, an average thickness of 10 μm or more and 200 μm or less, and the first Each of the second pressure-sensitive adhesive layers contains aluminum in an amount of 20% by volume to 60% by volume in 100% by volume of the first and second pressure-sensitive adhesive layers, and the average of the first and second pressure-sensitive adhesive layers. A double-sided PSA sheet having a thickness of 20 μm or more and 200 μm or less is provided.

  According to a wide aspect of the present invention, the heat generating component, the metal casing or the heat radiating component, and the double-sided pressure-sensitive adhesive sheet bonding the heat generating component and the metal casing or the heat radiating component are provided. The pressure-sensitive adhesive sheet comprises a base material, a first pressure-sensitive adhesive layer laminated on one surface of the base material, and a second pressure-sensitive adhesive layer laminated on the other surface of the base material. The material has an elastic modulus at 25 ° C. of 50 GPa or more and 300 GPa or less, a thermal conductivity of 100 W / m · K or more, an average thickness of 10 μm or more and 200 μm or less, and the first and second adhesives. Each of the adhesive layers contains 20 vol% or more and 60 vol% or less of aluminum in 100 vol% of the first and second adhesive layers, and the average thickness of the first and second adhesive layers is 20 μm, respectively. As described above, a connection structure having a size of 200 μm or less is provided.

  In this specification, both the invention regarding the double-sided pressure-sensitive adhesive sheet described above and the invention regarding the connection structure described above are disclosed.

  In the present invention, the double-sided pressure-sensitive adhesive sheet comprises at least a surface of the first pressure-sensitive adhesive layer opposite to the substrate side and a surface of the second pressure-sensitive adhesive layer opposite to the substrate side. It is preferable to further include a release liner laminated on one surface.

  The release liner preferably has an elastic modulus at 25 ° C. of 1 GPa or more and 10 GPa or less and an average thickness of 60 μm or more. The 180 ° maximum peel strength at 25 ° C. of the release liner with respect to the pressure-sensitive adhesive layer on which the release liner is laminated is 0.04 N / 25 mm or more and 0.5 N / 25 mm or less, and the first and second When an aluminum plate is attached to the surface of the pressure-sensitive adhesive layer opposite to the substrate side, the 180 ° average peel strength at 25 ° C. of the first and second pressure-sensitive adhesive layers with respect to the aluminum plate is respectively It is preferably 6 N / 25 mm or more and 50 N / 25 mm or less.

  In this invention, after the surface opposite to the said base material side of the said 1st adhesive layer is affixed on the 1st to-be-adhered body, the said double-sided adhesive sheet of the said 2nd adhesive layer The surface opposite to the substrate side is used by being attached to the second adherend, and the average thickness of the first pressure-sensitive adhesive layer attached to the first adherend is first, It is preferable that the thickness is 10% or more and 50% or less thinner than the average thickness of the second pressure-sensitive adhesive layer to be attached to the second adherend later.

  The first and second pressure-sensitive adhesive layers each have a (meth) acrylic acid ester resin having a weight average molecular weight of 500,000 to 1,500,000 and a pressure-sensitive adhesive having an alcoholic hydroxyl group and a hydroxyl value of 35 or more. An imparting resin and a terpene phenol resin. The tackifier resin is preferably a rosin ester resin. It is preferable that the content of the tackifying resin is 5 to 40 parts by weight and the content of the terpene phenol resin is 3 to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester resin.

  The surface of the base material is embossed, and the base material has a convex portion or a concave portion on the surface on which the first and second pressure-sensitive adhesive layers are laminated, and the average height of the convex portion or the The average depth of the recesses is preferably 1 μm or more, 20% or less of the thickness of the double-sided pressure-sensitive adhesive sheet, and 2 times or less of each average thickness of the first and second pressure-sensitive adhesive layers. The surface of the substrate is preferably oxidized. The substrate is preferably a metal foil.

  In the double-sided pressure-sensitive adhesive sheet according to the present invention, the first and second pressure-sensitive adhesive layers are laminated on both surfaces of the base material, and the base material has an elastic modulus at 25 ° C. of 50 GPa or more and 300 GPa or less, The thermal conductivity is 100 W / m · K or more, the average thickness is 10 μm or more and 200 μm or less, and the first and second pressure-sensitive adhesive layers are respectively in 100% by volume of the first and second pressure-sensitive adhesive layers. The aluminum sheet contains 20% by volume or more and 60% by volume or less, and the average thickness of the first and second pressure-sensitive adhesive layers is 20 μm or more and 200 μm or less, respectively. Further, handling properties can be improved.

  In the connection structure according to the present invention, a double-sided pressure-sensitive adhesive sheet in which the first and second pressure-sensitive adhesive layers are laminated on both surfaces of the base material is used, and the base material has an elastic modulus at 25 ° C. Is 50 GPa or more and 300 GPa or less, the thermal conductivity is 100 W / m · K or more, the average thickness is 10 μm or more and 200 μm or less, and the first and second pressure-sensitive adhesive layers are the first and second adhesive layers, respectively. Double-sided pressure-sensitive adhesive sheet because aluminum contains 20 volume% or more and 60 volume% or less in 100 volume% of the pressure-sensitive adhesive layer 2 and the average thickness of the first and second pressure-sensitive adhesive layers is 20 μm or more and 200 μm or less, respectively. As a result of high thermal conductivity and high handleability, a good connection structure can be obtained.

FIG. 1 is a partially cutaway front sectional view showing a double-sided pressure-sensitive adhesive sheet according to the first embodiment of the present invention. FIG. 2 is a partially cutaway front sectional view showing a state where the first and second adherends are bonded together using the double-sided pressure-sensitive adhesive sheet according to the first embodiment of the present invention. FIG. 3 is a partially cutaway front sectional view showing a double-sided pressure-sensitive adhesive sheet according to the second embodiment of the present invention. 4 (a) and 4 (b) are partial cutaway front sectional views showing a modification of the base material in the double-sided PSA sheet shown in FIG. FIG. 5 is a cross-sectional view showing an example of a connection structure using the double-sided pressure-sensitive adhesive sheet shown in FIG.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings.

  In FIG. 1, the double-sided adhesive tape which concerns on the 1st Embodiment of this invention is shown with a partial notch front sectional drawing.

  A double-sided pressure-sensitive adhesive sheet 1 shown in FIG. 1 includes a base material 2, a first pressure-sensitive adhesive layer 3 laminated on one surface 2 a (first surface) of the base material 2, and one of the base materials 2. And a second pressure-sensitive adhesive layer 4 laminated on the other surface 2b (second surface) opposite to the surface 2a. The surface 2a is a surface on which the first pressure-sensitive adhesive layer 3 is laminated. The surface 2b is a surface on which the second pressure-sensitive adhesive layer 4 is laminated.

  The surfaces 2a and 2b on both sides of the substrate 2 are embossed. Thereby, the base material 2 has the some convex part 2c on the surfaces 2a and 2b of both sides, respectively. Further, due to the convex portion 2 c of the base material 2, the first pressure-sensitive adhesive layer 3 has a plurality of convex portions 3 b on the surface 3 a opposite to the base material 2 side. Due to the convex portions 2 c of the base material 2, the second pressure-sensitive adhesive layer 4 has a plurality of convex portions 4 b on the surface 4 a opposite to the base material 2 side. Each of the surfaces of the first and second pressure-sensitive adhesive layers opposite to the substrate side may be flat.

  Moreover, the double-sided pressure-sensitive adhesive sheet 1 includes a first release liner 5 laminated on a surface 3 a opposite to the base material 2 side of the first pressure-sensitive adhesive layer 3. Furthermore, the double-sided pressure-sensitive adhesive sheet 1 includes a second release liner 6 laminated on the surface 4 a opposite to the base material 2 side of the second pressure-sensitive adhesive layer 4. A release liner is laminated on at least one of the surface of the first pressure-sensitive adhesive layer opposite to the substrate side and the surface of the second pressure-sensitive adhesive layer opposite to the substrate side. It only has to be. The first release liner 5 may be laminated only on the surface 3a, the second release liner 6 may be laminated only on the surface 4a, and the first release liner 5 is laminated on the surface 3a. The second release liner 6 may be laminated on the surface 4a.

  The elastic modulus at 25 ° C. of the substrate 2 is 50 GPa or more and 300 GPa or less. The thermal conductivity of the base material 2 is 100 W / m · K or more. The average thickness of the substrate 2 is 10 μm or more and 200 μm or less.

  Each of the first and second pressure-sensitive adhesive layers 3 and 4 includes a filler having a thermal conductivity of 5 W / m · K or more. In 100% by volume of the first and second pressure-sensitive adhesive layers 3 and 4, the content of the filler having a thermal conductivity of 5 W / m · K or more is 20% by volume or more and 60% by volume or less, respectively. The average thicknesses of the first and second pressure-sensitive adhesive layers 3 and 4 are 20 μm or more and 200 μm or less, respectively.

  In the double-sided pressure-sensitive adhesive sheet 1 according to this embodiment, the first and second pressure-sensitive adhesive layers 3 and 4 are laminated on the surfaces 2 a and 2 b on both sides of the base material 2, and the elastic modulus of the base material 2 at 25 ° C. The first and second pressure-sensitive adhesive layers 3 and 4 each contain aluminum at the specific content described above, and the first and second pressure-sensitive adhesive layers When the average thicknesses of 3 and 4 are within the specific ranges, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet 1 can be increased, and the handleability can be further improved.

  The high handleability means that the double-sided pressure-sensitive adhesive sheet is not easily bent without intention or has high handling properties. The cause of the bending is that the end of the substrate and the end of the release liner are caught when the release liner is peeled from the first and second pressure-sensitive adhesive layers, and the release liner is attached to the first and second release liners. Examples include a difference in elongation between the release liner, the base material, and the first and second adhesive layers when peeling from the adhesive layer.

  Moreover, when the filler contained in the 1st, 2nd adhesive layers 3 and 4 is aluminum, compared with the case where fillers other than aluminum, such as an alumina, are used at the time of use after adhesion or at the time of dropping. When an impact is applied, the adhesion between the double-sided PSA sheet and the object to be bonded can be made difficult to decrease.

  As shown in FIG. 2, the double-sided pressure-sensitive adhesive sheet 1 is peeled off from the first and second release liners 5 and 6, and is attached to the adherend in the state of the double-sided pressure-sensitive adhesive sheet 1A. The double-sided pressure-sensitive adhesive sheet 1 </ b> A preferably has the surface of the second pressure-sensitive adhesive layer 4 after the surface 3 a opposite to the substrate 2 side of the first pressure-sensitive adhesive layer 3 is attached to the first adherend 11. The surface 4a opposite to the base 2 side is attached to the second adherend 12 and used. In this case, preferably, before the surface 3a is attached to the first adherend 11, the first release liner 5 is peeled from the surface 3a of the first pressure-sensitive adhesive layer 3, and the first pressure-sensitive adhesive is removed. The surface 3a of the layer 3 is exposed, and then the first adherend 11 is attached to the exposed surface 3a. Next, the second release liner 6 is peeled from the surface 4a of the second pressure-sensitive adhesive layer 4 to expose the surface 4a of the second pressure-sensitive adhesive layer 4, and then the second surface is covered with the exposed surface 4a. The body 12 is pasted.

  In FIG. 3, the double-sided adhesive tape which concerns on the 2nd Embodiment of this invention is shown with a partial notch front sectional drawing.

  The double-sided pressure-sensitive adhesive sheet 21 shown in FIG. 3 includes a base material 22, a first pressure-sensitive adhesive layer 23 laminated on one surface 22 a (first surface) of the base material 22, and one of the base materials 22. And a second pressure-sensitive adhesive layer 24 laminated on the other surface 22b (second surface) opposite to the surface 22a. The surface 22a is a surface on which the first pressure-sensitive adhesive layer 23 is laminated. The surface 22b is a surface on which the second pressure-sensitive adhesive layer 24 is laminated. The surfaces 22a and 22b on both sides of the substrate 22 are not embossed. The surfaces 23a and 24a opposite to the base material 22 side of the first and second pressure-sensitive adhesive layers 23 and 24 are respectively flat.

  Moreover, the double-sided pressure-sensitive adhesive sheet 21 includes a first release liner 25 laminated on a surface 23 a opposite to the base material 22 side of the first pressure-sensitive adhesive layer 23. Furthermore, the double-sided pressure-sensitive adhesive sheet 21 includes a second release liner 26 laminated on the surface 24 a opposite to the base material 22 side of the second pressure-sensitive adhesive layer 24.

  Hereinafter, the details of the substrate, the first and second pressure-sensitive adhesive layers, and the first and second release liners will be described first. Then, the detail of a double-sided adhesive sheet is demonstrated.

(Base material)
The base material is a support for supporting the first and second pressure-sensitive adhesive layers. Examples of the substrate include metal foil, nonwoven fabric, paper, and plastic film. Especially, it is preferable that the said base material is metal foil from a viewpoint of improving the heat conductivity of a double-sided adhesive sheet further. Examples of the material of the metal foil include aluminum, copper, gold, and graphite sheet. Especially, since the heat conductivity of a double-sided adhesive tape becomes still higher, it is preferable that the said metal foil is gold foil, copper foil, or aluminum foil, and it is more preferable that it is aluminum foil. By using aluminum foil, it is possible to increase thermal conductivity, workability, and corrosion resistance, and to reduce costs. Also, aluminum is often used for the heat sink or LED metal substrate. For this reason, when the base material is an aluminum foil, the followability to deformation becomes high due to thermal expansion or the like, so that the heat resistance is improved. The higher the purity of the aluminum foil, the higher the thermal conductivity. Therefore, the purity of the aluminum foil is preferably 99.9% by weight or more. Table 1 below shows the elastic modulus and thermal conductivity of some of the substrates.

  The elastic modulus at 25 ° C. of the substrate is 50 GPa or more and 300 GPa or less. When the elastic modulus of the substrate is less than 50 GPa, the double-sided pressure-sensitive adhesive sheet is easily stretched when the adherend is bonded to the double-sided pressure-sensitive adhesive sheet, and the double-sided pressure-sensitive adhesive sheet is difficult to handle. When the elastic modulus of the base material exceeds 300 GPa, when the double-sided pressure-sensitive adhesive sheet is punched out, burrs or burrs are generated and the adhesiveness of the double-sided pressure-sensitive adhesive sheet is lowered or it becomes difficult to emboss the base material. Or the cut surface becomes sharp when the double-sided PSA sheet is cut. In order to further improve the handleability of the double-sided PSA sheet, the elastic modulus of the substrate is preferably 1 GPa or more. When the elasticity modulus of a base material is too low, a base material will be extended at the time of a sticking operation | work, and workability | operativity will fall. The elastic modulus of the substrate is preferably 100 GPa or less.

  The elastic modulus of the substrate can be measured using, for example, “Tensilon” manufactured by Orientec Co., Ltd. The measurement conditions are that the substrate is cut into a width of 10 mm, the distance between chucks is 50 mm, and the pulling speed is 50 mm / min.

  The thermal conductivity of the substrate is 100 W / m · K or more. For this reason, the heat conductivity of a double-sided adhesive sheet can be made high. The upper limit of the thermal conductivity of the substrate is not particularly limited. The higher the thermal conductivity of the substrate, the better, and there is virtually no upper limit.

  The average thickness of the substrate is 10 μm or more and 200 μm or less. When the average thickness of the substrate is 10 μm or less, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet is lowered, the mechanical strength is lowered, or the handleability is lowered. If the average thickness of the substrate exceeds 200 μm, the mechanical strength of the double-sided pressure-sensitive adhesive sheet becomes too high, or it becomes difficult to make the double-sided pressure-sensitive adhesive sheet adhere to the adherend along the shape of the adherend. When the adhesive sheet is cut, burrs are generated, and the adhesion between the double-sided adhesive sheet and the adherend is reduced. Furthermore, since the thickness of the double-sided pressure-sensitive adhesive sheet is excessively large, it may be difficult to meet the demand for downsizing electronic devices or communication devices using the double-sided pressure-sensitive adhesive sheet. In order to further increase the thermal conductivity of the double-sided PSA sheet, the average thickness of the substrate is preferably 20 μm or more, more preferably 30 μm or more. In order to increase the flexibility of the double-sided pressure-sensitive adhesive sheet and meet the demand for thinning in various applications, the average thickness of the double-sided pressure-sensitive adhesive sheet is preferably 500 μm or less, more preferably 200 μm or less.

  It is preferable that at least one surface of the substrate is embossed. The substrate is preferably embossed on both surfaces where the first and second pressure-sensitive adhesive layers are laminated. By the embossing, convex portions or concave portions are formed on the base material, and a thick portion and a thin portion are formed. Due to the thick part of the substrate, the thermal conductivity of the double-sided PSA sheet is increased. Due to the thin part of the substrate, the adhesiveness of the double-sided PSA sheet to the adherend increases. Therefore, the high thermal conductivity and high adhesion of the double-sided PSA sheet can be achieved by embossing.

  The base material 2 in the double-sided pressure-sensitive adhesive sheet 1 shown in FIG. 1 has a plurality of convex portions 2c on both surfaces 2a and 2b. The positions of the plurality of projections 2 c provided on the surface 2 a and the positions of the plurality of projections 2 c provided on the back surface 2 b coincide with each other in the thickness direction of the substrate 2. That is, the convex part 2c is provided in both the parts which surface 2a, 2b opposes. Thus, it is preferable that the positions of the plurality of protrusions 2 c provided on the surface 2 a and the positions of the plurality of protrusions 2 c provided on the back surface 2 b coincide with each other in the thickness direction of the substrate 2. . In this case, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet is further increased.

  4A and 4B show a modification of the base material. The substrate 51 shown in FIG. 4A has a plurality of convex portions 51c on the surfaces 51a and 51b on both sides. The positions of the plurality of protrusions 51 c provided on the surface 51 a and the positions of the plurality of protrusions 51 c provided on the surface 51 b do not match in the thickness direction of the substrate 51. On the surface 51b at the position of the plurality of convex portions 51c provided on the surface 51a, concave portions between the convex portions 51c are located. That is, in the part where the surfaces 51a and 51b face each other, the convex portion 51c is provided on one surface 51a, and the concave portion is provided on the other surface 51b. The base material 52 shown in FIG. 4B has a plurality of convex portions 52c only on one surface 52a, and does not have convex portions on the other surface 52b.

  The shape of the emboss is not limited to the shape shown in FIGS. 1, 4A, and 4B. Examples of the shape of the emboss include a shape such as a triangular wave, a rectangular wave, or a sine wave in cross section, and a shape provided with a partially cylindrical protrusion.

  Examples of the method for forming the emboss include a lip emboss method and a roll emboss method. Of these, the roll embossing method is preferable. As a method for forming the embossing, specifically, the base material is molded between a shaping roll having a concave portion or a convex portion on the surface and another roll, or between the two shaping rolls. A method is mentioned. Examples of the other rolls include rubber rolls and metal rolls. The surface of the other roll may be flat.

  The substrate preferably has a convex portion or a concave portion on at least one surface. It is preferable that the base material has a convex portion or a concave portion on both surfaces on which the first and second pressure-sensitive adhesive layers are laminated. This convex portion or concave portion is preferably formed by embossing. The average height of the convex portions or the average depth of the concave portions of the substrate is preferably 1 μm or more, more preferably 30 μm or less. The average height of the convex portions or the average depth of the concave portions of the substrate is preferably 20% or less of the thickness of the double-sided pressure-sensitive adhesive sheet, and preferably 5% or more. The average height of the convex portions or the average depth of the concave portions of the base material is preferably 0.5 times or less of each average thickness of the first and second pressure-sensitive adhesive layers, and is 0.1 times or more. It is preferable. By providing the convex portions or concave portions as described above on the surface of the base material, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet is further increased, and the adhesion between the double-sided pressure-sensitive adhesive sheet and the adherend is further improved. Become. In addition, when there is no adhesive layer on the front-end | tip of a convex part and the cross section of a convex part is triangular shape, half of the height of a convex part becomes an average thickness of an adhesive layer. For example, if there is a pressure-sensitive adhesive layer on the tip of the convex part so that it does not come into contact with the heat sink, the surface of the base material is embossed compared to a double-sided pressure-sensitive adhesive sheet where the surface of the base material is not embossed. The thermal conductivity of the double-sided PSA sheet is high. The average height of the convex part or the average depth of the concave part is a value in the thickness direction of the substrate.

  The pitch of the convex portions (the distance between the centers of the adjacent convex portions) or the pitch of the concave portions (the distance between the centers of the adjacent concave portions) can be appropriately changed depending on the shape of the adherend. The pitch of the convex portions or the pitch of the concave portions is preferably 100 μm or more, more preferably 1 cm or less.

(First and second adhesive layers)
Each of the first and second pressure-sensitive adhesive layers contains a filler having a thermal conductivity of 5 W / m · K or more. The filler is aluminum. Aluminum is a filler having a thermal conductivity of 5 W / m · K or more. By using aluminum, the thermal conductivity of the double-sided PSA sheet and the first and second PSA layers can be increased. When the first and second pressure-sensitive adhesive layers contain a filler having a thermal conductivity of less than 5 W / m · K, it is difficult to sufficiently increase the thermal conductivity of the double-sided pressure-sensitive adhesive sheet.

  Examples of the filler having a thermal conductivity of 5 W / m · K or more include metal fillers such as aluminum, magnesium, stainless steel, iron, and copper. Examples of the filler having a thermal conductivity of 5 W / m · K or more include alumina, synthetic magnesite, crystalline silica, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, aluminum hydroxide, and hydroxide. Also included are metal compounds such as magnesium and magnesium carbonate. Use of these preferable fillers further increases the thermal conductivity of the double-sided PSA sheet.

  In the present invention, aluminum is used as a filler having a thermal conductivity of 5 W / m · K or more. Use of aluminum further increases the thermal conductivity of the double-sided PSA sheet. Use of aluminum not only increases the thermal conductivity of the double-sided pressure-sensitive adhesive sheet, but also makes it difficult to reduce the adhesion between the double-sided pressure-sensitive adhesive sheet and the object to be bonded when an impact is applied after use or when dropped. be able to. The term “filler” described below includes aluminum.

  The filler may be a spherical filler or a crushed filler. The filler is particularly preferably spherical. In the case of a spherical filler, since it can be filled with a high density, the thermal conductivity of the double-sided PSA sheet is further increased.

  The crushed filler can be obtained, for example, by crushing massive inorganic substances using a uniaxial crusher, a biaxial crusher, a hammer crusher, a ball mill, or the like. By using the crushed filler, the filler in the pressure-sensitive adhesive layer tends to have a structure that is bridged or effectively brought close together. Therefore, when the filling amount of the crushed filler is the same as the filling amount of the spherical filler, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet is further increased. Moreover, the crushed filler is generally cheaper than a normal filler. For this reason, the cost of a double-sided adhesive sheet becomes low by use of the crushed filler.

  The average particle size of the crushed filler is preferably 12 μm or less, more preferably 10 μm or less, and preferably 1 μm or more. When the average particle size of the crushed filler is not less than the above lower limit and not more than the above upper limit, it is easy to fill the crushed filler with high density in the pressure-sensitive adhesive layer.

  The aspect ratio of the crushed filler is not particularly limited. The aspect ratio of the crushed filler is preferably 1.5 or more and 20 or less. Fillers with an aspect ratio of less than 1.5 are relatively expensive. Therefore, the cost of the double-sided pressure-sensitive adhesive sheet increases. When the aspect ratio is 20 or less, filling of the crushed filler in the pressure-sensitive adhesive layer is easy.

  The aspect ratio of the crushed filler can be determined, for example, by measuring the crushed surface of the filler using a digital image analysis type particle size distribution measuring apparatus (trade name: FPA, manufactured by Nippon Luft).

  When the filler is a spherical filler, the average particle diameter of the spherical filler is preferably 0.1 μm or more and 40 μm or less. When the average particle size is 0.1 μm or more, the filler can be easily filled at a high density. When the average particle diameter is 40 μm or less, the thickness of the pressure-sensitive adhesive layer can be reduced.

  The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a laser diffraction particle size distribution measuring apparatus.

  In 100 volume% of 1st adhesive layers, content of aluminum is 20 volume% or more and 60 volume% or less. In 100 volume% of the 2nd adhesive layer, content of aluminum is 20 volume% or more and 60 volume% or less. When the aluminum content in the first and second pressure-sensitive adhesive layers is less than 20% by volume, the thermal conductivity of the double-sided pressure-sensitive adhesive sheet is lowered. When the content of aluminum in the first and second pressure-sensitive adhesive layers exceeds 60% by volume, the adhesive force on the surfaces of the first and second pressure-sensitive adhesive layers becomes low. In order to further increase the thermal conductivity of the double-sided PSA sheet, the aluminum content in the first and second PSA layers is preferably 25% by volume or more, more preferably 30% by volume or more. In order to further increase the adhesive strength of the first and second pressure-sensitive adhesive layers, the aluminum content in each of the first and second pressure-sensitive adhesive layers is preferably 55% by volume or less, more preferably 50% by volume. It is as follows.

  Examples of the resin used for the first and second pressure-sensitive adhesive layers include siloxane resins, (meth) acrylic acid ester resins, and polyolefin resins. Especially, since it is excellent in adhesiveness, (meth) acrylic acid ester resin is preferable. “(Meth) acryl” means acrylic and methacrylic.

  Each of the first and second pressure-sensitive adhesive layers preferably contains a (meth) acrylic acid ester resin having a weight average molecular weight of 500,000 to 1,500,000. Each of the first and second pressure-sensitive adhesive layers preferably contains a tackifier resin having an alcoholic hydroxyl group and a hydroxyl value of 35 or more. Each of the first and second pressure-sensitive adhesive layers preferably contains a terpene phenol resin. The 1st adhesive layer and the 2nd adhesive layer may be formed with the same material, and may be formed with a different material.

  The first and second pressure-sensitive adhesive layers are the (meth) acrylic acid ester resin, a tackifying resin having an alcoholic hydroxyl group and a hydroxyl value of 35 or more, an alcoholic hydroxyl group and a hydroxyl value. By including the tackifier resin which is 35 or more and the terpene phenol resin, the adhesiveness to the adherend of the double-sided PSA sheet is further enhanced.

  The (meth) acrylic acid ester resin is preferably a polymer using (meth) acrylic acid ester as a polymerization component. As for (meth) acrylic acid ester resin, only 1 type may be used and 2 or more types may be used together.

  As said acrylic ester resin, (meth) acrylic acid alkyl ester resin which homopolymerized (meth) acrylic acid alkyl ester monomer, (meth) acrylic acid which copolymerized 2 or more types of (meth) acrylic acid alkyl ester monomers Examples thereof include alkyl ester resins and copolymers of (meth) acrylic acid alkyl ester monomers and other vinyl monomers copolymerizable with the (meth) acrylic acid alkyl ester monomers. Among these, a copolymer of a (meth) acrylic acid alkyl ester monomer and another vinyl monomer copolymerizable with the (meth) acrylic acid alkyl ester monomer is preferable.

  The (meth) acrylic acid ester is preferably a (meth) acrylic acid ester obtained by an esterification reaction between a primary or secondary alkyl alcohol having 1 to 12 carbon atoms and (meth) acrylic acid.

  Specific examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate and 2 -Ethylhexyl (meth) acrylate.

  Other examples of polymerization components for obtaining the (meth) acrylic acid ester include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and maleic anhydride, and glycidyl acrylate and allyl. Examples thereof include epoxy group-containing monomers such as glycidyl ether.

  The other vinyl monomer copolymerizable with the (meth) acrylic acid alkyl ester monomer is used for the purpose of increasing the cohesive strength of the pressure-sensitive adhesive layer. Examples of the other vinyl monomer include a vinyl monomer that increases the glass transition temperature (Tg) of the acrylate resin, and a vinyl monomer that contributes to forming a crosslinked structure between the main chains of the (meth) acrylate resin. Etc.

  It does not specifically limit as a vinyl monomer which raises Tg of the said (meth) acrylic acid ester resin, A carboxy group containing monomer, a hydroxyl group containing monomer, maleic anhydride, vinyl acetate, styrene, etc. are mentioned. Examples of the carboxy group-containing monomer include (meth) acrylic acid, crotonic acid, maleic acid, and itaconic acid. Examples of the hydroxyl group-containing monomer include n-methylolacrylamide. Among them, acrylic acid is preferable because it hardly affects the control of the molecular weight of the (meth) acrylic ester resin and can increase the adhesiveness of the pressure-sensitive adhesive layer.

  The content ratio of the structural unit derived from the vinyl monomer that raises the Tg in the total structural unit of 100% by weight of the (meth) acrylic ester resin is preferably 0.01% by weight or more, more preferably 0.05% by weight. % Or more, preferably 10% by weight or less, more preferably 5% by weight or less. When the content ratio of the structural unit derived from the vinyl monomer that raises the Tg is not less than the above lower limit, the Tg of the pressure-sensitive adhesive layer can be sufficiently increased, and the cohesive force of the pressure-sensitive adhesive layer can be increased. When the content ratio of the structural unit derived from the vinyl monomer that raises the Tg is not more than the above upper limit, the adhesive strength and tack of the pressure-sensitive adhesive layer are further improved.

  Examples of the vinyl monomer that contributes to the formation of a crosslinked structure between the main chains of the (meth) acrylate resin include hydroxyl group-containing (meth) acrylate.

  By using the hydroxyl group-containing (meth) acrylic acid ester monomer and an isocyanate crosslinking agent or epoxy crosslinking agent described later, the gel fraction of the first and second pressure-sensitive adhesive layers can be easily adjusted to 5 to 40% by weight. Moreover, the resilience resistance and peeling resistance of the pressure-sensitive adhesive layer can be enhanced.

  Examples of the hydroxyl group-containing (meth) acrylic acid ester monomer include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-3-hydroxypropyl, (meta ) -2-hydroxybutyl acrylate, 4-hydroxybutyl (meth) acrylate and caprolactone adducts thereof.

  The content ratio of the structural unit derived from the hydroxyl group-containing (meth) acrylic ester is preferably 1% by weight or more, more preferably 5% by weight or more, in 100% by weight of the total structural units of the (meth) acrylic ester resin. , Preferably 50% by weight or less, more preferably 30% by weight or less. When the content ratio of the structural unit derived from the hydroxyl group-containing (meth) acrylic acid ester is not less than the above lower limit, it is easy to control the gel fraction of the pressure-sensitive adhesive layer to an appropriate range, and the gel fraction of the pressure-sensitive adhesive layer is moderate. It is not necessary to use a large amount of a crosslinking agent in order to adjust to such a range, and the resilience resistance of the pressure-sensitive adhesive layer is improved. When the content ratio of the structural unit derived from the hydroxyl group-containing (meth) acrylic acid ester is not more than the above upper limit, the gel fraction of the pressure-sensitive adhesive layer does not become too high, and the gel fraction is in an appropriate range with a small amount of a crosslinking agent. Furthermore, since the variation in the amount of the crosslinking agent in the pressure-sensitive adhesive layer is reduced, a uniform crosslinked structure is easily obtained.

  The weight average molecular weight of the (meth) acrylic ester resin is preferably 550,000 or more, more preferably 3 million or less, and still more preferably 900,000 or less. When the weight average molecular weight is equal to or more than the lower limit, the pressure-sensitive adhesive layer is more difficult to be peeled off from the adherend due to the peeling stress caused by the deformation of the adherend. When the weight average molecular weight is not more than the above upper limit, the adhesive force of the pressure-sensitive adhesive layer is further improved, and the pressure-sensitive adhesive layer is further peeled off from the adherend due to the peeling stress caused by the deformation of the adherend. It becomes difficult to do.

  The said weight average molecular weight shows the weight average molecular weight in polystyrene conversion measured by the gel permeation chromatography. For example, the weight average molecular weight can be measured using a filtrate obtained by diluting the (meth) acrylic acid ester resin 50-fold with tetrahydrofuran using a filter. For this gel permeation chromatography, a trade name “2690 Separations Model” manufactured by Water is used. Moreover, as a column used for the measurement of the said weight average molecular weight, Shodex GPC LF-804 (made by Showa Denko KK) etc. are mentioned, for example.

  The (meth) acrylic acid ester resin is obtained by polymerizing a polymerization component such as the (meth) acrylic acid ester using a polymerization initiator. Examples of the polymerization method include solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

  The polymerization initiator is not particularly limited. For example, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypi Valet, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, Examples thereof include t-butyl peroxyisobutyrate, t-butyl peroxy-3,5,5-trimethylhexanoate and t-butyl peroxylaurate. Of these, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane or t-hexylperoxypivalate is preferable. As for the said polymerization initiator, only 1 type may be used and 2 or more types may be used together.

  The content of the (meth) acrylate resin is preferably 50% by weight or more, more preferably 60% by weight or more, preferably in 100% by weight of all components excluding the filler in the first and second pressure-sensitive adhesive layers. Is 99% by weight or less, more preferably 80% by weight or less. When the content of the (meth) acrylic ester resin is not less than the above lower limit and not more than the above upper limit, the thermal conductivity of the double-sided PSA sheet can be sufficiently secured, and the adhesion of the double-sided PSA sheet to the adherend is even better. become.

  The tackifying resin has an alcoholic hydroxyl group. By using the tackifier resin having an alcoholic hydroxyl group, even if the adherend is deformed, the pressure-sensitive adhesive layer is hardly peeled off from the adherend. The tackifier resin preferably has a hydroxyl value of 35 or more. The tackifying resin is not particularly limited, and examples thereof include rosin ester resins and hydrogenated terpene phenol resins. Only 1 type may be used for tackifying resin and 2 or more types may be used together.

  From the viewpoint of further suppressing peeling of the double-sided PSA sheet from the adherend, the tackifier resin is preferably a rosin ester resin, and more preferably a polymerized rosin ester resin.

  Examples of the rosin ester resin include a rosin resin mainly composed of abietic acid, a disproportionated rosin resin and a hydrogenated rosin resin, and a dimer (polymerized rosin resin) of a resin acid such as abietic acid. It is a rosin ester resin obtained by esterifying with an alcohol, in which some of the hydroxyl groups of the alcohols used for esterification are not esterified. Esterified rosin resin is rosin ester resin, disproportionated rosin resin esterified product is disproportionated rosin ester resin, hydrogenated rosin resin esterified product is hydrogenated rosin ester resin, polymerized rosin resin esterified product is polymerized rosin ester Resin.

  Examples of the alcohols used for the esterification include polyhydric alcohols. Examples of the polyhydric alcohol include ethylene glycol, glycerin and pentaerythritol.

  The hydroxyl value of the tackifying resin is preferably 35 or more, more preferably 40 or more, preferably 60 or less, more preferably 58 or less. It can suppress that a double-sided adhesive sheet peels from a to-be-adhered body with the peeling stress which arises with a deformation | transformation of a to-be-adhered body as the said hydroxyl value is more than the said minimum. When the hydroxyl value is less than or equal to the above upper limit, for example, when a crosslinking agent such as an isocyanate crosslinking agent is added to crosslink the pressure-sensitive adhesive, poor crosslinking is less likely to occur. The hydroxyl value of the tackifying resin is measured according to JIS K0070.

  The softening point of the tackifying resin is preferably 140 ° C. or higher, more preferably 145 ° C. or higher, preferably 170 ° C. or lower, more preferably 165 ° C. or lower. When the softening point of the tackifying resin is not less than the above lower limit and not more than the above upper limit, even when the thickness of the pressure-sensitive adhesive layer is thin, the pressure-sensitive adhesive force, rebound resistance, and follow-up of deformation to the adherend Good. When the softening point is equal to or higher than the lower limit, when heat is applied to the pressure-sensitive adhesive layer and when the pressure-sensitive adhesive layer is used for a long time, the flowability of the pressure-sensitive adhesive layer does not become too large, and the double-sided pressure-sensitive adhesive sheet is covered. It becomes difficult to peel from the kimono. When the softening point of the tackifying resin is not more than the above upper limit, the pressure-sensitive adhesive layer does not become too hard, and the double-sided pressure-sensitive adhesive sheet can be prevented from peeling off from the adherend when the adherend is deformed. The softening point of the tackifying resin is measured according to JIS K2207.

  The content of the tackifier resin is preferably 5 parts by weight or more, preferably 8 parts by weight or more, preferably 40 parts by weight or less, more preferably 35 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester resin. Or less. It can suppress that a double-sided adhesive sheet peels from a to-be-adhered body with the peeling stress which arises with a deformation | transformation of a to-be-adhered body as content of tackifying resin is more than the said minimum. When the content of the tackifying resin is not more than the above upper limit, the pressure-sensitive adhesive layer does not become too hard, and the pressure-sensitive adhesive force and tack of the pressure-sensitive adhesive layer are further improved.

  The terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol. The terpene phenol resin does not include a hydrogenated terpene phenol resin obtained by hydrogenating a terpene phenol resin. The aromatic ring in the terpene phenol resin contributes to an improvement in adhesive strength.

  The softening point of the terpene phenol resin is preferably 140 ° C. or higher, more preferably 145 ° C. or higher, and preferably 170 ° C. or lower. The heat resistance of an adhesive layer becomes it high that the softening point of the said terpene phenol resin is more than the said minimum. When the softening point of the terpene phenol resin is less than or equal to the above upper limit, the pressure-sensitive adhesive layer does not become too hard, the adhesive force and tack become even better, and further, due to the peeling stress that occurs with the deformation of the adherend, It can suppress that a double-sided adhesive sheet peels from an adherend. The softening point of the terpene phenol resin is measured according to JIS K2207.

  The content of the terpene phenol resin is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, preferably 20 parts by weight or less, more preferably 15 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester resin. Less than parts by weight. When the content of the terpene phenol resin is not less than the above lower limit, the heat resistance and adhesive strength of the pressure-sensitive adhesive layer are further improved. It can suppress that a double-sided adhesive sheet peels from a to-be-adhered body with the peeling stress which arises with a deformation | transformation of a to-be-adhered body as content of a terpene phenol resin is below the said upper limit.

  A commercial item may be used as an adhesive containing the above-mentioned (meth) acrylic acid ester resin. Examples of such commercially available products include Esdyne series manufactured by Soken Chemical Co., Ltd., and Aron Tuck series manufactured by Toagosei Co., Ltd.

  In the first and second pressure-sensitive adhesive layers, it is preferable that a crosslinking structure is formed between the main chains of the resin constituting the pressure-sensitive adhesive layer using a crosslinking agent. By adjusting the kind and content of the crosslinking agent, the gel fraction of the pressure-sensitive adhesive layer can be easily adjusted to a desired range.

  As said crosslinking agent, an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, a metal chelate type crosslinking agent, etc. are mentioned. Of these, isocyanate crosslinking agents are preferred. A urethane bond is formed by the reaction between the isocyanate group in the isocyanate crosslinking agent and the alcoholic hydroxyl group in the tackifying resin. Due to this urethane bond, peeling of the double-sided PSA sheet from the adherend due to peeling stress caused by deformation of the adherend becomes difficult to occur. Furthermore, the adhesiveness of the said base material and the said adhesive layer becomes high by use of an isocyanate crosslinking agent.

  The compounding quantity of the said crosslinking agent can be suitably adjusted with the kind of crosslinking agent, and is not specifically limited. The content of the crosslinking agent is preferably 0.05 parts by weight or more and preferably 1.7 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic ester resin. When the content of the crosslinking agent is not less than the above lower limit, the resin in the pressure-sensitive adhesive layer is sufficiently crosslinked. When the content of the crosslinking agent is not more than the above upper limit, the adhesive force and tack of the pressure-sensitive adhesive layer are further improved.

  When using an epoxy crosslinking agent, the content of the epoxy crosslinking agent is preferably 0.05 parts by weight or more, more preferably 0.07 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic ester resin. , Preferably 0.17 parts by weight or less, more preferably 0.15 parts by weight or less. When the content of the epoxy crosslinking agent is not less than the above lower limit, the resin in the pressure-sensitive adhesive layer is sufficiently crosslinked. When the content of the crosslinking agent is not more than the above upper limit, the adhesive force and tack of the pressure-sensitive adhesive layer are further improved.

  Each of the first and second pressure-sensitive adhesive layers may contain additives such as a plasticizer, an emulsifier, a softener, a filler, a pigment, and a dye as necessary. When a filler such as a filler or a pigment is used, the average particle diameter of the filler is preferably 5% or less of each thickness of the first and second pressure-sensitive adhesive layers. The maximum particle diameter of the filler is preferably 10% or less of each thickness of the first and second pressure-sensitive adhesive layers.

  When the substrate is an aluminum foil, the first and second pressure-sensitive adhesive layers are each made of an aluminum chelating material or a silane coupling agent in order to enhance the adhesion between the aluminum foil and the pressure-sensitive adhesive layer. May be included.

  The average thicknesses of the first and second pressure-sensitive adhesive layers are 20 μm or more and 200 μm or less, respectively. When the average thickness of the first and second pressure-sensitive adhesive layers is within the above range, the handleability of the double-sided pressure-sensitive adhesive sheet is enhanced. From the viewpoint of further improving the handleability of the double-sided pressure-sensitive adhesive sheet, the average thickness of the first and second pressure-sensitive adhesive layers is preferably 10 μm or more, and preferably 200 μm or less. When the average thickness of the first and second pressure-sensitive adhesive layers is not less than the above lower limit and not more than the above upper limit, the surface opposite to the substrate side of the first pressure-sensitive adhesive layer is attached to the first adherend. After the application, when the release liner laminated on the surface of the second pressure-sensitive adhesive layer is peeled off, the release liner can be peeled off more easily.

(Release liner)
By using a release liner, the handleability of the double-sided pressure-sensitive adhesive sheet can be improved, and further, foreign matter can be prevented from adhering to the pressure-sensitive adhesive layer.

  The material of the release liner is not particularly limited. For example, ethylene-vinyl acetate copolymer resin, polyurethane resin, polyester resin such as polyethylene terephthalate resin, polytetrafluoroethylene resin, polyethylene resin, polypropylene resin, polymethylpentene resin, Examples thereof include polyolefin resin of polyvinyl acetate resin, polyvinyl chloride resin, polyimide resin, and release paper. Among these, from the viewpoint of facilitating the release of the release liner, the material of the release liner is preferably a polyethylene resin. The surface of the release liner on the first and second pressure-sensitive adhesive layer sides may be subjected to a release treatment. Furthermore, a release agent such as silicone may be applied to the surface of the release liner on the first and second pressure-sensitive adhesive layer sides in order to improve the releasability.

  The elastic modulus at 25 ° C. of the release liner is preferably 1 GPa or more and 10 GPa or less. When the above elastic modulus of the release liner is within this range, the handleability of the double-sided pressure-sensitive adhesive sheet is further enhanced. The elastic modulus of the release liner is more preferably 2 GPa or more, and more preferably 4 GPa or less. Further, after the elastic modulus of the release liner is not less than the above lower limit and not more than the above upper limit, after the surface opposite to the substrate side of the first pressure-sensitive adhesive layer is attached to the first adherend, When the release liner laminated on the surface of the pressure-sensitive adhesive layer is peeled off, the release liner can be peeled off more easily without bending the double-sided pressure-sensitive adhesive sheet excluding the release liner. Table 2 below shows the elastic modulus of some release liners.

  The elastic modulus of the release liner can be measured using, for example, “Tensilon” manufactured by Orientec Co., Ltd. The measurement conditions are that the substrate is cut into a width of 10 mm, the distance between chucks is 50 mm, and the pulling speed is 50 mm / min.

  The average thickness of the release liner is preferably 10 μm or more, more preferably 60 μm or more, and still more preferably the lower limit is 80 μm or more. When the average thickness of the release liner is not less than the above lower limit, the release liner can be more easily peeled from the first and second pressure-sensitive adhesive layers. The average thickness of the release liner is preferably 500 μm or less, more preferably 200 μm or less. When the average thickness of the release liner is not more than the above upper limit, the thickness of the double-sided pressure-sensitive adhesive sheet does not become too thick.

(Double-sided adhesive sheet)
The double-sided pressure-sensitive adhesive sheet according to the present invention can be used for applications in which various first adherends and various second adherends are bonded together.

  The double-sided pressure-sensitive adhesive sheet according to the present invention is preferably a base material for the second pressure-sensitive adhesive layer after the surface opposite to the base material side of the first pressure-sensitive adhesive layer is attached to the first adherend. The surface opposite to the side is used by being attached to the second adherend. In this case, the average thickness T1 (μm) of the first pressure-sensitive adhesive layer that is first attached to the first adherend is the average of the second pressure-sensitive adhesive layer that is subsequently attached to the second adherend. It is preferably thinner than the thickness T2 (μm), preferably 10% or more and 50% or less. The average thickness T1 is preferably (0.9 × T2) or less, more preferably (0.8 × T2) or less, and preferably (0.5 × T2) or more. When average thickness T1 and average thickness T2 satisfy | fill the said relationship, the adhesiveness of the double-sided adhesive sheet with respect to a to-be-adhered body can be improved, ensuring the high heat conductivity of a double-sided adhesive sheet.

  The 180 ° maximum peel strength P1 at 25 ° C. of the release liner with respect to the pressure-sensitive adhesive layer on which the release liner is laminated is preferably 0.04 N / 25 mm or more, more preferably 0.06 N / 25 mm or more, preferably 0.5 N / 25 mm or less, more preferably 0.3 N / 25 mm or less. 180 ° average peel strength at 25 ° C. of the first and second pressure-sensitive adhesive layers with respect to the aluminum plate when an aluminum plate is attached to the surface opposite to the base material side of the first and second pressure-sensitive adhesive layers Each P2 is preferably 6 N / 25 mm or more, more preferably 8 N / 25 mm or more, preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less. When the peel strengths P1 and P2 are not less than the above lower limit and not more than the above upper limit, a release liner laminated on the second pressure-sensitive adhesive layer is bonded to the adherend such as an aluminum plate. When peeled, the double-sided PSA sheet becomes difficult to peel partially from the adherend. The peel strengths P1 and P2 are measured according to JIS Z0237.

  As a manufacturing method of a double-sided adhesive sheet, the following method is mentioned, for example. However, the manufacturing method of a double-sided adhesive sheet is not limited to the following 1st-3rd methods.

  1st method: A solvent and a filler are added to an adhesive, and an adhesive solution is prepared. This pressure-sensitive adhesive solution is applied onto the surface of the substrate, and the solvent in the pressure-sensitive adhesive solution is removed by drying to form a first pressure-sensitive adhesive layer. Next, on the surface opposite to the base material side of the first pressure-sensitive adhesive layer, a first release liner (release film) is laminated to obtain a first laminated film. Subsequently, the pressure-sensitive adhesive solution is applied on the surface of the second release liner (release film), and the solvent in the pressure-sensitive adhesive solution is removed by drying to form a second pressure-sensitive adhesive layer. 2 laminated film is obtained. The exposed surface of the second pressure-sensitive adhesive layer of the second laminated film and the exposed surface of the base material of the first laminated film are bonded together to obtain a laminate. Then, the laminate is pressed with a rubber roller or the like. In this way, a double-sided pressure-sensitive adhesive sheet in which the second release liner, the first pressure-sensitive adhesive layer, the base material, the second pressure-sensitive adhesive layer, and the second release liner are laminated in this order is obtained.

  Second method: The pressure-sensitive adhesive solution (solution prepared by the first method) is applied onto the surface of the first release liner, the solvent in the pressure-sensitive adhesive solution is removed by drying, and the first pressure-sensitive adhesive is removed. An agent layer is formed to obtain a first laminated film. Further, the pressure-sensitive adhesive solution is applied onto the surface of the second release liner (release film), and the solvent in the pressure-sensitive adhesive solution is removed by drying to form a second pressure-sensitive adhesive layer. A laminated film is obtained. The first laminated film is laminated on one surface of the substrate from the first pressure-sensitive adhesive layer side, and the second laminated film is laminated on the other surface of the substrate from the second pressure-sensitive adhesive layer side. To obtain a laminate. The obtained laminate is pressed with a rubber roller or the like in the same manner as in the first method to obtain a double-sided pressure-sensitive adhesive sheet.

  Third method: The first laminated film described in the first method is prepared. In the first laminated film, the first pressure-sensitive adhesive layer and the first release liner are laminated in this order on one surface of the substrate. The second pressure-sensitive adhesive is applied to the other surface of the substrate of the first laminated film by applying the pressure-sensitive adhesive solution (the solution prepared by the first method) and removing the solvent in the pressure-sensitive adhesive solution by drying. Form a layer. Next, a second release liner (release film) is laminated on the exposed surface of the second pressure-sensitive adhesive layer to obtain a laminate. The obtained laminate is pressed with a rubber roller or the like in the same manner as in the first method to obtain a double-sided pressure-sensitive adhesive sheet.

  As a method for applying the adhesive solution, a knife coater or an applicator is generally used. In the case of continuous coating, generally, a three reverse coater, a direct gravure coater, a direct bar coater, a bar reverse coater, a die coater or the like is preferably used.

  It may be necessary to perform a re-peeling operation, for example, when a displacement occurs when the double-sided PSA sheet is bonded to an adherend. At this time, the substrate and the pressure-sensitive adhesive layer are peeled off, and the pressure-sensitive adhesive layer is transferred to the adherend, and a phenomenon called adhesive residue may occur. This is likely to occur when the height of the convex portion or the depth of the concave portion of the adherend is larger than the height of the convex portion or the concave portion of the substrate. It is thought that the main cause is that the pressure-sensitive adhesive layer becomes more comfortable with the unevenness of the adherend over time, the anchor effect is increased, and the functional group present in the pressure-sensitive adhesive layer is bonded to the aluminum plate. As a method for preventing the adhesive residue, for example, a method of providing an anchor coat layer on a base material, a surface of the base material is polished with a sandpaper or a buff or the like, and a convex portion height or a concave portion depth of the base material is covered. A method of increasing the height of the convex portion or the depth of the concave portion of the adherend, a method of removing foreign matter adhering to the surface of the base material by corona treatment or plasma treatment, anodizing the surface of the base material, etc. Examples thereof include a method of forming an oxide film, and a method of plating with chromium or nickel.

  As a method for providing the anchor coat layer on the substrate, specifically, when the substrate is an aluminum foil, a method of applying a silane coupling agent or an aluminum-based chelating material to the surface of the substrate, etc. It is done.

  The double-sided PSA sheet may be used after being cut (cut out or punched out) into a predetermined size as necessary.

  The double-sided pressure-sensitive adhesive sheet according to the present invention constitutes an insulating layer of a laminated structure in which a conductive layer is laminated on at least one side of a heat conductor having a thermal conductivity of 10 W / m · K or more via a double-sided pressure-sensitive adhesive sheet. It is suitably used for this purpose. Moreover, the double-sided pressure-sensitive adhesive sheet according to the present invention is suitably used for bonding a heat generating component and a metal casing or a heat dissipation component. The double-sided pressure-sensitive adhesive sheet according to the present invention obtains a connection structure having a heat generating component, a metal casing or a heat radiating component, and the double-sided pressure-sensitive adhesive sheet bonding the heat generating component and the metal casing or the heat radiating component. Therefore, it is preferably used. Furthermore, the double-sided pressure-sensitive adhesive sheet according to the present invention is suitably used for bonding a heating element such as an LED or a CPU and a heat radiating member such as a heat sink. Specifically, for example, it can be used for bonding an LED substrate on which an LED is mounted on a CCL formed of an aluminum plate-insulating layer-copper foil and a heat sink.

  Specifically as said heat-emitting component, CPU, a board | substrate, etc. are mentioned. Specific examples of the heat radiating component or the metal casing include a heat spreader and a heat sink.

  The heat dissipation component is preferably a heat conductor having a thermal conductivity of 10 W / m · K or more. Examples of the heat conductor include aluminum, copper, alumina, beryllia, silicon carbide, silicon nitride, aluminum nitride, and a graphite sheet. Especially, it is preferable that the said heat conductor is copper or aluminum. Copper or aluminum is excellent in thermal conductivity.

  FIG. 5 is a sectional view showing an example of the connection structure 61 using the double-sided pressure-sensitive adhesive sheet according to the second embodiment of the present invention shown in FIG.

  In FIG. 5, the release liners 25 and 26 in the double-sided pressure-sensitive adhesive sheet 21 are peeled off, and a heat diffusion plate 62 is attached to the outer surface 23 a of the first pressure-sensitive adhesive layer 23. The heat diffusion plate 62 is, for example, a CCL. A heating element 63 is laminated on the surface of the heat diffusion plate 62 opposite to the first pressure-sensitive adhesive layer 23 side. A heat sink 64 is attached to the outer surface 24 a of the second pressure-sensitive adhesive layer 24.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

  The following materials were prepared.

[Base material]
Al foil A (aluminum foil, average thickness 50 μm, elastic modulus 70 GPa at 25 ° C., thermal conductivity 237 W / m · K)
Embossed Al foil B (aluminum foil with embossed surfaces on both sides and convex portions formed, average thickness 50 μm, average height of convex portions 10 μm, elastic modulus 70 GPa at 25 ° C., thermal conductivity 237 W / m · K)

[Adhesive layer]
<Material of pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer>
Other fillers having a thermal conductivity of 10 W / m · K or more:
(1) Crushed alumina (crushed filler, manufactured by Nippon Light Metal Co., Ltd., trade name: LT300C, average particle diameter 5 μm, maximum particle diameter 15 μm, thermal conductivity 36 W / m · K, new Mohs hardness 12, density 3.9)
(2) Spherical alumina (Denka Co., Ltd., trade name: DAM-10, average particle size 10 μm, maximum particle size 30 μm, thermal conductivity 36 W / m · K, new Mohs hardness 12, density 3.9)
(3) Spherical aluminum (manufactured by Eka Granular Japan, trade name JTF-10: average particle size 5.0 μm, thermal conductivity 237 W / m · K, new Mohs hardness 2, density 2.69)

Other fillers having a thermal conductivity of less than 10 W / m · K:
(1) Talc (manufactured by Nippon Talc Co., Ltd., trade name: K-1, average particle size 8 μm, new Mohs hardness 1, density 2.8)

(Meth) acrylic ester resin:
(1) Acrylic ester resin solution A
Esdyne SK1502 (manufactured by Soken Chemical Co., Ltd., containing 30% by weight of rosin ester-based tackifier)
(2) Acrylic ester resin solution B
(Solution containing 30% by weight of (meth) acrylate resin obtained in Synthesis Example 1 below, 20% by weight of structural unit derived from ethyl acrylate, weight average molecular weight 62000)

(Synthesis Example 1)
A reactor equipped with a thermometer, a stirrer, and a cooling pipe was prepared. In this reactor, 20 parts by weight of ethyl acrylate, 56.9 parts by weight of acrylic acid-n-butyl, 20 parts by weight of 2-ethylhexyl acrylate, and 0.1 parts by weight of 2-hydroxyethyl acrylate Then, 3 parts by weight of acrylic acid and 70 parts by weight of ethyl acetate were added, and then the reactor was heated to start refluxing. Subsequently, 0.01 parts by weight of 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane was added as a polymerization initiator in the reactor, and polymerization was started under reflux. It was. Next, after 1 hour and 2 hours from the start of polymerization, 0.01 parts by weight of 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane was added, and the polymerization was started. 4 hours later, 0.05 part by weight of t-hexylperoxypivalate was added to continue the polymerization reaction. 8 hours after the start of polymerization, ethyl acetate was added to the reactor and cooled while diluting to obtain an acrylate resin solution A having a solid content of 30% by weight.

Tackifying resin:
(1) Hydrogenated rosin ester resin A (Arakawa Chemical Industries, trade name “Pine Crystal KE359”, hydroxyl value: 40, softening point: 100 ° C.)
(2) Terpene phenol resin A (manufactured by Yasuhara Chemical Co., Ltd., trade name “Mighty Ace G150”, softening point: 150 ° C.)

Cross-linking agent:
Isocyanate cross-linking agent (Nippon Polyurethane, trade name “Coronate L45”)

  Using the above materials, a pressure-sensitive adhesive was obtained according to the following preparation example.

(Adhesive preparation example)
The adhesive shown in the following Tables 3 and 4 with respect to 100 parts by weight of the solid content of the acrylic ester resin solutions A to B in any of the acrylic ester resin solutions A to B obtained as described above. By adding the imparting resin and filler in the amounts shown in Tables 3 and 4 below, adding ethyl acetate and stirring, and further adding the crosslinking agent in the amounts shown in Tables 3 and 4 below and stirring, An adhesive having a solid content of 40% by volume was obtained. In addition, the compounding quantity of each component in following Table 3, 4 shows the weight part in solid content of each component.

[Release liner]
Release PET (Release polyethylene terephthalate, manufactured by Toyo Cloth, “SP-4106”, one surface is release-treated with a silicone release material, elastic modulus at 25 ° C. 3600 MPa, average thickness 100 μm)
Release paper (polyethylene laminate release paper, manufactured by Sumika Kogyo Co., Ltd., “SLB-70WOTP”, both surfaces are release-treated with a silicone release material, elastic modulus at 25 ° C., 2800 MPa, 110 μm), peel force: 34 mN / 25mm

Example 1
An adhesive having the composition shown in Table 3 below was applied to the release-treated PET (first release liner) surface side, dried at 100 ° C. for 5 minutes to remove ethyl acetate, and the average thickness The first pressure-sensitive adhesive layer was formed so as to have the thickness shown in Table 3 below. The Al foil A was laminated on the surface of the first pressure-sensitive adhesive layer to obtain a first laminated film.

  Subsequently, an adhesive having the composition shown in Table 3 below was applied on the release-treated surface of the release paper (second release liner), dried at 100 ° C. for 5 minutes to remove ethyl acetate, and the average A second pressure-sensitive adhesive layer was formed so that the thickness was as shown in Table 3 below, and a second laminated film was obtained.

  The first laminated film was laminated on the surface of the second pressure-sensitive adhesive layer of the obtained second laminated film from the substrate side to obtain a laminated body.

  Lamination was performed by reciprocating a 2 kg rubber roller at a speed of 300 mm / min, and then stored at 23 ° C. for 7 days. In this way, a double-sided pressure-sensitive adhesive sheet in which release PET, first pressure-sensitive adhesive layer, Al foil A, second pressure-sensitive adhesive layer, and release paper were laminated in this order was obtained.

(Examples 2-9, Reference Examples 1-8 and Comparative Examples 1-5)
The composition of the pressure-sensitive adhesive, the type of substrate and the type of release liner were set as shown in Tables 3 and 4 below, and the average thicknesses of the first and second pressure-sensitive adhesive layers are shown in Tables 3 and 4 below. A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the settings were made as shown.

(Evaluation)
The peelability, tackiness, and peelability of the release liner of the double-sided PSA sheet obtained as described above were measured as follows. Moreover, sensory evaluation was performed about sheet | seat handleability (peelability). The results are shown in Tables 3 and 4.

(1) Peel strength P1 (Peelability)
The double-sided pressure-sensitive adhesive sheet was cut into a width of 5 mm. The 2nd release liner was peeled from the surface of the 2nd adhesive layer, and the surface of the 2nd adhesive layer was exposed. By laminating an aluminum plate of JIS H4000 A5052P having a thickness of 1 μm on the exposed surface of the second pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum plate at a speed of 300 mm / min, The 2nd adhesive layer and the aluminum plate were bonded together and the 1st test sample was obtained.

  Using the obtained first test sample, in accordance with JIS Z0237, a tensile test in the 180 ° direction was performed at a peeling speed of 300 mm / min, and the first pressure-sensitive adhesive layer on which the first release liner was laminated The 180 ° average peel strength P1-1-1 and the maximum peel strength P1-1-2 at 25 ° C. of the first release liner were measured.

  Moreover, the double-sided adhesive sheet was cut into a width of 5 mm. The release liner was peeled off from the surface of the first pressure-sensitive adhesive layer to expose the surface of the first pressure-sensitive adhesive layer. By laminating an aluminum plate of JIS H4000 A5052P having a thickness of 1 μm on the exposed surface of the first pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum plate at a speed of 300 mm / min, The 1st adhesive layer and the aluminum plate were bonded together and the 2nd test sample was obtained.

  Using the obtained second test sample, in accordance with JIS Z0237, a tensile test in the 180 ° direction was performed at a peeling speed of 300 mm / min, and the second pressure-sensitive adhesive layer on which the second release liner was laminated The 180 ° average peel strength P1-2-1 and the maximum peel strength P1-2-2 at 25 ° C. of the second release liner were measured.

(2) Peel strength P2 (adhesiveness)
The double-sided pressure-sensitive adhesive sheet was cut into a width of 5 mm. The release liner was peeled off from the surface of the first pressure-sensitive adhesive layer to expose the surface of the first pressure-sensitive adhesive layer. By laminating an aluminum plate of JIS H4000 A5052P having a thickness of 1 μm on the exposed surface of the first pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum plate at a speed of 300 mm / min, The 1st adhesive layer and the aluminum plate were bonded together.

  Subsequently, the release liner was peeled off from the surface of the second pressure-sensitive adhesive layer to expose the surface of the second pressure-sensitive adhesive layer. By laminating an aluminum foil having a thickness of 12 μm on the exposed surface of the second pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum foil at a speed of 300 mm / min, the second pressure-sensitive adhesive The layer and the aluminum foil were bonded together to obtain a first test sample.

  Using the obtained first test sample, in accordance with JIS Z0237, a tensile test in the 180 ° direction was performed at a peeling speed of 300 mm / min, and the first pressure-sensitive adhesive layer on the aluminum plate was 180 ° at 25 ° C. Average peel strength P2-1 was measured.

  The double-sided pressure-sensitive adhesive sheet was cut into a width of 5 mm. The release liner was peeled off from the surface of the second pressure-sensitive adhesive layer to expose the surface of the second pressure-sensitive adhesive layer. By laminating an aluminum plate of JIS H4000 A5052P having a thickness of 1 μm on the exposed surface of the second pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum plate at a speed of 300 mm / min, The 2nd adhesive layer and the aluminum plate were bonded together.

  Subsequently, the release liner was peeled off from the surface of the first pressure-sensitive adhesive layer to expose the surface of the first pressure-sensitive adhesive layer. By laminating an aluminum foil having a thickness of 12 μm on the exposed surface of the first pressure-sensitive adhesive layer, and reciprocating a 2 kg rubber roller on the surface of the aluminum foil at a speed of 300 mm / min, the first pressure-sensitive adhesive The layer and the aluminum foil were bonded together to obtain a second test sample.

  Using the obtained second test sample, in accordance with JIS Z0237, a tensile test in the 180 ° direction was performed at a peeling speed of 300 mm / min, and the second pressure-sensitive adhesive layer on the aluminum plate was 180 ° at 25 ° C. Average peel strength P2-2 was measured.

(3) Cross peeling test The double-sided PSA sheet was cut into 20 mm x 20 mm to obtain a test piece. The first release liner is peeled off from the surface of the first pressure-sensitive adhesive layer of the test piece, placed on the center of an aluminum plate having a length of 50 mm, a width of 30 mm, and a thickness of 3 mm, and a speed of 300 mm / min on the back surface of the test piece. The test piece and the hot plate were attached by reciprocating a 2 kg rubber roller once. The second release liner is peeled off from the surface of the second pressure-sensitive adhesive layer, an aluminum plate of the same size is placed so that the angle formed by the two aluminum plates is 90 °, and a load of 100 g is adhered over 1 minute. After that, the load was removed. A vertical peel test was performed at a peel rate of 1 mm / min so that the aluminum plate attached to the second pressure-sensitive adhesive layer peeled in the vertical direction, and the maximum peel strength P3 was measured.

(4) Thermal conductivity The double-sided PSA sheet was cut into 30 mm x 30 mm to obtain a test piece. The first release liner is peeled off from the surface of the first pressure-sensitive adhesive layer of the test piece, placed on a hot plate, and the test piece is reciprocated once by a 2 kg rubber roller on the back surface of the test piece at a speed of 300 mm / min. And a hot plate. The second release liner was peeled off from the surface of the second pressure-sensitive adhesive layer, and an aluminum plate having a size of 20 mm × 20 mm × thickness 20 mm was placed thereon. After 1 kg of load was adhered for 1 minute, the load was removed. The hot plate was set at 80 ° C., and the surface temperature of the aluminum plate attached to the second adhesive layer after 30 minutes was measured. It can be said that the higher the surface temperature of the aluminum plate, the higher the thermal conductivity of the double-sided PSA sheet.

(5) Handleability of double-sided PSA sheet (high-speed peelability)
The following criteria evaluated the ease of the operation | work which laminates | stacks an adhesive layer on a base material, and the operation | work at the time of cutting a sheet | seat.

  The double-sided PSA sheet was cut out to 5 mm × 300 mm to obtain a test piece. The first release liner is peeled off from the surface of the first pressure-sensitive adhesive layer of the test piece, placed on an aluminum plate having a width of 4 mm, a length of 300 mm, and a thickness of 1 mm, and 2 kg at a speed of 300 mm / min on the back surface of the test piece. The test piece and the aluminum plate were attached by reciprocating the rubber roller. Subsequently, the second release liner was peeled from the surface of the second pressure-sensitive adhesive layer within 1 minute at a high speed over 1 second.

[Criteria for handling (high speed peelability)]
○: The test piece and the aluminum plate are not peeled, and the entire surface is evenly adhered. Δ: The peel having a diameter of about 2 mm occurs. ×: The peel is greatly separated at the interface between the test piece and the aluminum plate.

  In addition, when mold release PET was used, there existed a place where peeling strength becomes high in some places because the peeling surface has a fault.

(6) Adhesiveness of double-sided pressure-sensitive adhesive sheet to aluminum plate After the evaluation of the handleability of the above-mentioned (5) double-sided pressure-sensitive adhesive sheet, a drop impact test was conducted using a laminate of a test piece and an aluminum plate (1500G, 0. 5 ms, half sine wave, 30 times (JEDEC JESD22-B111)). When this drop impact test was performed, it was evaluated whether or not the peel strength between the test piece and the aluminum plate was lowered.

[Judgment criteria for adhesion of double-sided PSA sheet to aluminum plate]
○○: The above (5) double-sided pressure-sensitive adhesive sheet has a handleability determination result of “◯”, and a peel strength of 90% or more is maintained when a drop impact test is performed. ○: (5) Double-sided pressure-sensitive adhesive sheet The result of the determination of the handleability is “◯” or “Δ”, and when the drop impact test is performed, the peel strength is reduced to 50% or more and less than 90%. ×: (5) Handleability of the double-sided pressure-sensitive adhesive sheet The judgment result of is “×”

  The results are shown in Tables 3 and 4 below.

  In Example 7 and Reference Example 8, the determination results of the adhesion of the double-sided PSA sheet to the aluminum plate are both “◯”, but the decrease in peel strength is greater in Example 7. It was considerably smaller than Reference Example 8.

DESCRIPTION OF SYMBOLS 1, 1A, 21 ... Double-sided adhesive sheet 2,22 ... Base material 2a, 2b, 22a, 22b ... Surface 2c ... Convex part 3, 23 ... 1st adhesive layer 3a, 23a ... Surface 3b ... Convex part 4,24 ... second adhesive layer 4a, 24a ... surface 4b ... convex part 5,25 ... first release liner 6,26 ... second release liner 11 ... first adherend 12 ... second adherend 51, 52 ... base material 51a, 51b, 52a, 52b ... surface 51c, 52c ... convex part 61 ... connection structure 62 ... heat diffusion plate 63 ... heating element 64 ... heat sink

Claims (7)

Heat-generating parts,
A metal housing or heat dissipation component;
It has a double-sided pressure-sensitive adhesive sheet that bonds the heat-generating component and the metal casing or heat-radiating component,
The double-sided pressure-sensitive adhesive sheet comprises a base material, a first pressure-sensitive adhesive layer laminated on one surface of the base material, and a second pressure-sensitive adhesive layer laminated on the other surface of the base material,
The base material has an elastic modulus at 25 ° C. of 50 GPa or more and 300 GPa or less, a thermal conductivity of 100 W / m · K or more, an average thickness of 10 μm or more and 200 μm or less,
Each of the first and second pressure-sensitive adhesive layers contains 20% by volume to 60% by volume of aluminum in 100% by volume of the first and second pressure-sensitive adhesive layers,
The connection structure which the average thickness of the said 1st, 2nd adhesive layer is 20 micrometers or more and 200 micrometers or less, respectively.   Each of the first and second pressure-sensitive adhesive layers has a (meth) acrylic acid ester resin having a weight average molecular weight of 500,000 to 1,500,000 and a pressure-sensitive adhesive having an alcoholic hydroxyl group and a hydroxyl value of 35 or more. The connection structure according to claim 1, comprising an imparting resin and a terpene phenol resin.   The connection structure according to claim 2, wherein the tackifying resin is a rosin ester resin.   The content of the tackifying resin is 5 to 40 parts by weight and the content of the terpene phenol resin is 3 to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester resin. The connection structure described in 1. The surface of the substrate is embossed,
The base material has a convex portion or a concave portion on the surface on which the first and second pressure-sensitive adhesive layers are laminated,
The average height of the convex part or the average depth of the concave part is 1 μm or more, 20% or less of the thickness of the double-sided pressure-sensitive adhesive sheet, and twice or less of each average thickness of the first and second pressure-sensitive adhesive layers. The connection structure according to any one of claims 1 to 4.   The connection structure according to claim 1, wherein a surface of the base material is oxidized.   The connection structure according to claim 1, wherein the base material is a metal foil.

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