JP2019137714A - Adhesive sheet and method for producing the same, and graphite sheet laminate - Google Patents

Abstract

To provide an adhesive sheet which can transfer an embossed shape on an adhesive surface, exhibits good air removability when stuck by the embossed shape and has sufficient durability while being a thin film and a method for producing the same and to provide a graphite sheet laminate having good air removability when stuck and sufficient durability while being a thin film.SOLUTION: There is provided an adhesive sheet 1 equipped with a substrate 2 and a first adhesive layer 31 laminated on one surface side of the substrate 2, wherein the substrate 2 has a thickness of 0.5 μm or more and 15 μm or less, the first adhesive layer 31 has a thickness of 1 μm or more and 14 μm or less and an adhesive constituting the first adhesive layer 31 has a relaxation modulus G (300) after 300 sec. at 23°C of 1000 Pa or more and 2500 Pa or less and a gel fraction of 30% or more and 70% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive sheet that can suppress air accumulation between the pressure-sensitive adhesive surface and an adherend during sticking, a method for producing the same, and a graphite sheet laminate.

  In recent years, in electronic devices such as smartphones, tablet terminals, and personal computers, heat generation of electronic components constituting the electronic devices has become a problem. In order to solve this heat generation problem, a graphite sheet having an excellent heat dissipation function is bonded to an electronic component. This graphite sheet has become very thin as electronic devices become thinner.

  As described above, a double-sided pressure-sensitive adhesive sheet may be used for bonding a graphite sheet to an electronic component. Examples of such a double-sided PSA sheet include those disclosed in Patent Document 1. The pressure-sensitive adhesive layer of this double-sided pressure-sensitive adhesive sheet is also required to be a thin film in order to reduce the thickness of the electronic device.

  When a graphite sheet is attached to an electronic component using the double-sided pressure-sensitive adhesive sheet as described above, the double-sided pressure-sensitive adhesive sheet is usually bonded to the graphite sheet in advance, and then the graphite sheet is passed through the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet. Is attached to the electronic component. However, since the graphite sheet is very thin and has low rigidity, air can easily be trapped between the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer and the electronic component when being attached to the electronic component. When such air pockets exist, there is a problem that the heat dissipation by the graphite sheet is not sufficiently exhibited.

  It is also known to form a groove for air removal (air escape) on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer in order to prevent air accumulation between the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer and the adherend. . For example, Patent Document 2 discloses forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive to the release surface of an embossed release sheet as a method of forming a groove for air removal on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer. ing.

JP2015-124302A JP2011-000769A

  The pressure-sensitive adhesive disclosed in Patent Document 2 is a general acrylic pressure-sensitive adhesive, and in the examples, a solvent-type acrylic pressure-sensitive adhesive (“BPS” manufactured by Toyo Ink Co., Ltd.) to which a predetermined amount of isocyanate is added as a crosslinking agent. -8170 ") is used.

  However, as described above, when a general acrylic pressure-sensitive adhesive is applied to the release surface of the embossed release sheet to form a pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive can be made less than the height of the emboss. There is a problem that the pressure-sensitive adhesive layer cannot be thinned.

  On the other hand, as a method for forming an air escape groove on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer, it is conceivable to transfer the embossed shape of the embossed release sheet to the pressure-sensitive adhesive layer formed as usual. However, when the embossed shape is formed on the pressure-sensitive adhesive layer by transfer, the embossed shape cannot be transferred with the pressure-sensitive adhesive layer having high cohesive force. Therefore, it is necessary to reduce the cohesive force of the adhesive to such an extent that the embossed shape can be transferred. In that case, there was a problem that durability of the obtained pressure-sensitive adhesive layer becomes insufficient due to the fact that the pressure-sensitive adhesive layer is a thin film.

  The present invention has been made in view of such a situation, and the embossed shape can be transferred to the adhesive surface. The embossed shape exhibits a good air escape property at the time of application and is a thin film. It is an object of the present invention to provide a pressure-sensitive adhesive sheet having sufficient durability, a method for producing the same, and a graphite sheet laminate that has good air detachability at the time of application and has sufficient durability while being a thin film.

  In order to achieve the above object, first, the present invention is a pressure-sensitive adhesive sheet comprising a base material and a first pressure-sensitive adhesive layer laminated on one surface side of the base material, wherein the base material Of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer, wherein the thickness of the first pressure-sensitive adhesive layer is 1 μm or more and 14 μm or less. Provided is a pressure-sensitive adhesive sheet having a relaxation elastic modulus G (300) at 300 ° C. after 300 seconds of 1000 Pa to 2500 Pa and a gel fraction of 30% to 70% (Invention 1).

  In the said invention (invention 1), when the 1st adhesive layer satisfy | fills said requirements, an uneven | corrugated shape can be formed in the adhesive surface of a 1st adhesive layer by the transfer of embossing shape, The uneven shape can maintain the shape until pasting. Thereby, the said adhesive sheet exhibits favorable air-release property at the time of sticking. Moreover, in the said invention (invention 1), since a 1st adhesive layer satisfy | fills said requirements, while an adhesive has an appropriate cohesive force and it is excellent in the uneven | corrugated shape loss | disappearance property after sticking, it is 1st Even if the pressure-sensitive adhesive layer is a thin film, it has excellent durability.

  In the present specification, “embossed shape transfer” does not only mean forming a shape obtained by inverting all of the concavo-convex shape, but it is a convex portion (up to the middle of the convex portion in the height direction). It may also mean that a concave portion having a shape corresponding to the above may be formed.

  In the said invention (invention 1), it is preferable that the uneven | corrugated shape is formed in the adhesive surface of a said 1st adhesive layer (invention 2).

  In the said invention (invention 1 and 2), the peeling sheet in which the peeling surface becomes uneven | corrugated shape is on the opposite side to the said base material in a said 1st adhesive layer, and the said peeling surface is said 1st adhesion. It is preferable to laminate so as to be located on the agent layer side (Invention 3).

  In the said invention (invention 3), it is preferable that the peeling surface of the said peeling sheet is formed with the convex part whose height is 0.1 micrometer or more and 50 micrometers or less (invention 4).

  In the said invention (invention 1-4), it is preferable that the adhesive which comprises the said 1st adhesive layer contains a polyrotaxane compound (invention 5).

  In the said invention (invention 1-5), it is preferable that the adhesive which comprises the said 1st adhesive layer is an acrylic adhesive (invention 6).

  In the said invention (invention 1-6), it is preferable that the 2nd adhesive layer is laminated | stacked on the other surface side of the said base material (invention 7).

  In the said invention (invention 1-7), it is preferable that the thickness of the said 2nd adhesive layer is 1 micrometer or more and 8 micrometers or less (invention 8).

  The pressure-sensitive adhesive sheet according to the above invention (Invention 1 to 8) is preferably attached to a graphite sheet (Invention 9).

  Secondly, the present invention provides a pressure-sensitive adhesive having a relaxation elastic modulus G (300) after 300 seconds at 23 ° C. of 1000 Pa or more and 2500 Pa or less and a gel fraction of 30% or more on one surface side of the substrate. The pressure-sensitive adhesive layer is formed through a curing period, and then, the release surface of the release sheet having a concavo-convex release surface is brought into contact with the pressure-sensitive adhesive layer, and the release sheet is attached to the pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet manufacturing method is provided (Invention 10).

  3rdly, this invention is a graphite sheet laminated body provided with the graphite sheet and the 1st adhesive layer provided in the one surface side of the said graphite sheet, Comprising: The said 1st adhesive layer is comprised. Provided is a graphite sheet laminate in which the pressure-sensitive adhesive has a relaxation elastic modulus G (300) after 300 seconds of 23 ° C. of 1000 Pa to 2500 Pa and a gel fraction of 30% or more ( Invention 11).

  In the said invention (invention 11), the peeling sheet in which the peeling surface becomes uneven | corrugated shape is on the opposite side to the said graphite sheet in a said 1st adhesive layer, and the said peeling surface is a said 1st adhesive layer. It is preferable to be laminated so as to be located on the side (Invention 12).

  In the said invention (invention 11 and 12), between the said graphite sheet and the said 1st adhesive layer, the 2nd adhesive layer located in the said graphite sheet side, and the said 1st adhesive layer side It is preferable that the base material located in this is interposed (invention 13).

  The pressure-sensitive adhesive sheet and the graphite sheet laminate according to the present invention are excellent in emboss shape transferability of the pressure-sensitive adhesive surface, and can exhibit good air detachability at the time of application due to the emboss shape, and are excellent in durability even though they are thin films. Moreover, according to the manufacturing method of the adhesive sheet which concerns on this invention, while having favorable air-release property at the time of sticking, it can manufacture the adhesive sheet which is excellent in durability, although it is a thin film.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is a top view which shows an example of the adhesion surface of the 1st adhesive layer in the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the graphite sheet laminated body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to the present embodiment includes a base material and a first pressure-sensitive adhesive layer laminated on one surface side of the base material. And the thickness of a base material is 0.5 micrometer or more and 15 micrometers or less, The thickness of a 1st adhesive layer is 1 micrometer or more and 14 micrometers or less, and the adhesive which comprises the 1st adhesive layer The relaxation elastic modulus G (300) after 300 seconds at 23 ° C. is 1000 Pa to 2500 Pa, and the gel fraction is 30% to 70%.

  In the pressure-sensitive adhesive sheet according to this embodiment, when the first pressure-sensitive adhesive layer satisfies the above-described requirements, an uneven shape can be formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer by embossed transfer. Furthermore, the formed uneven shape can maintain the shape until pasting. Therefore, when the adherend is stuck, the air between the adhesive surface of the first adhesive layer and the adherend is likely to escape outside through the air flow path formed by the uneven shape of the adhesive surface. Thus, even if the base material of the pressure-sensitive adhesive sheet is thin as described above, and even if the sheet provided on the other surface side of the base material, particularly the graphite sheet, is thin, the pressure-sensitive adhesive surface and the adherend are adhered. It is possible to effectively suppress air accumulation between the two. The pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer refers to the entire surface of the first pressure-sensitive adhesive layer on the side opposite to the base material and in contact with the adherend.

  Moreover, in the adhesive sheet which concerns on this embodiment, when a 1st adhesive layer satisfy | fills said requirements, it will have an appropriate cohesion force. Therefore, although the said adhesive sheet is a thin film, it will be excellent also about durability assumed in the use environment of a graphite sheet. Furthermore, the groove formed in the first pressure-sensitive adhesive layer is filled by pressing for discharging the air when the pressure-sensitive adhesive sheet according to the present embodiment is attached to the adherend, and subsequent pressing, etc. Almost disappear. Thereby, there is almost no gap between the first pressure-sensitive adhesive layer and the adherend, and the durability is improved.

  In the pressure-sensitive adhesive sheet according to this embodiment, it is preferable that an uneven shape is formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer. In addition, on the opposite side of the first pressure-sensitive adhesive layer from the substrate, a release sheet having a concavo-convex shape (first release sheet) is provided, and the release surface is on the first pressure-sensitive adhesive layer side. It is preferable to be laminated so as to be positioned. Further, a second pressure-sensitive adhesive layer is preferably laminated on the other surface side of the base material. In this case, the said adhesive sheet turns into a double-sided adhesive sheet which has a base material as a core material. Note that a non-contact portion may exist between the release surface of the release sheet (first release sheet) and the first pressure-sensitive adhesive layer. Moreover, the 2nd peeling sheet may be laminated | stacked on the opposite side to the base material in a 2nd adhesive layer. Here, the release surface of the release sheet in the present specification is a surface on the side in contact with the pressure-sensitive adhesive layer, which means a surface having releasability with respect to the pressure-sensitive adhesive layer, and whether or not there is a release treatment is not questioned. .

A specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in FIG.
As shown in FIG. 1, an adhesive sheet 1 according to an embodiment includes a base material 2, a first adhesive layer 31 laminated on one surface side of the base material 2, and the other surface of the base material 2. The second adhesive layer 32 laminated on the side, the first release sheet 41 laminated on the opposite side of the base material 2 in the first adhesive layer 31, and the base in the second adhesive layer 32. A second release sheet 42 laminated on the side opposite to the material 2 is provided.

1. Each member 1-1. Base Material The base material 2 of the pressure-sensitive adhesive sheet 1 according to the present embodiment supports the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32, and the pressure-sensitive adhesive sheet 1 (the pressure-sensitive adhesive sheet 1 excluding the release sheets 41 and 42). Has a function of giving a predetermined rigidity. Thus, when one release sheet (second release sheet 42) is peeled off, it occurs at the interface between the other release sheet (first release sheet 41) and the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer 31). Lifting and peeling can be effectively prevented.

  In the pressure-sensitive adhesive sheet according to the present invention, the second pressure-sensitive adhesive layer and the second release sheet are not essential constituent requirements. When these are not present, the substrate 2 can be an object to be attached to a desired adherend.

  As described above, the thickness of the substrate 2 is 15 μm or less. Thus, even if the base material 2 is thin, the pressure-sensitive adhesive sheet 1 according to the present embodiment exhibits a good air escape property at the time of sticking. Moreover, when the base material 2 is thin as mentioned above, the graphite sheet laminated body mentioned later can be formed thinly. From this viewpoint, the thickness of the base material 2 is preferably 10 μm or less, particularly preferably 6 μm or less, and further preferably 4 μm or less.

  Further, as described above, the thickness of the base material 2 is 0.5 μm or more. Thereby, predetermined | prescribed rigidity can be given to the adhesive sheet 1 (adhesive sheet 1 except the peeling sheets 41 and 42). From this viewpoint, the thickness of the substrate 2 is preferably 1.0 μm or more, and particularly preferably 1.5 μm or more.

  The base material 2 is not particularly limited as long as it satisfies the above thickness and can laminate the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32.

  Examples of the substrate 2 include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polyethylene film and polypropylene film, cellulose films such as triacetyl cellulose, polyvinyl chloride films, and polyvinylidene chloride. Film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polyurethane film, polystyrene film, polycarbonate film, polyimide film, polyetheretherketone film, polyetherimide film, polyethersulfone film, polyphenylsulfone film, Polyphenylene sulfide film, aramid film, nylon film, acrylic Aluminum, metal foils such as copper; nonwoven; resin film, norbornene resin film, a plastic film such as a cycloolefin resin film which the or mainly of these two or more laminates or the like. Note that “mainly” means that a desired layer thinner than those may be provided.

  Among these, a plastic film that can be easily thinned and has high smoothness is preferable, and among them, a polyolefin film and a polyester film excellent in mechanical strength and economy are preferable, and a polyethylene terephthalate film is particularly preferable.

  In the plastic film, for the purpose of improving the adhesion between the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32 provided on the surface, a surface treatment by an oxidation method or a concavo-convex method, or a primer, if desired. Processing can be performed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. Examples include a thermal spraying method. These surface treatment methods are appropriately selected according to the type of the resin film, but generally, a corona discharge treatment method is preferably used from the viewpoints of effects and operability.

1-2. 1st adhesive layer The 1st adhesive layer 31 in the adhesive sheet 1 which concerns on this embodiment is an adhesive layer stuck in contact with a desired to-be-adhered body. As described above, the relaxation elastic modulus G (300) after 23 seconds at 300C of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 31 is 2500 Pa or less. Since the relaxation elastic modulus G (300) is so small, the embossed shape is easily transferred to the adhesive surface of the first pressure-sensitive adhesive layer 31, that is, the embossed shape transferability is excellent. Moreover, it becomes easy to fill the groove | channel formed in the 1st adhesive layer 31 by the press of the adhesive sheet 1 stuck on the to-be-adhered body. From this viewpoint, the relaxation elastic modulus G (300) is preferably 2300 Pa or less, and particularly preferably 2000 Pa or less.

  On the other hand, the lower limit value of the relaxation elastic modulus G (300) is preferably 1000 Pa or more, particularly preferably 1300 Pa or more, and further preferably 1600 Pa or more. When the lower limit value of the relaxation elastic modulus G (300) is the above, the formed concavo-convex shape is not deformed by a force applied when the first release sheet 41 is peeled off, and the shape is maintained until the time of sticking and air is removed. Sex can be secured.

  In addition, the relaxation elastic modulus G (300) after 300 seconds shall mean the relaxation elastic modulus measured 300 seconds after distorting 10% of an adhesive based on JISK7244-1. The specific measurement method is as shown in the test examples described later.

  Further, as described above, the gel fraction of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 31 is 30% or more. When the gel fraction is 30% or more, the pressure-sensitive adhesive has a predetermined cohesive force, and the uneven shape formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer 31 is easily maintained well until sticking. At the same time, it is excellent in durability while being a thin film. From this viewpoint, the gel fraction of the pressure-sensitive adhesive is preferably 33% or more, and particularly preferably 35% or more.

  On the other hand, the gel fraction of the pressure-sensitive adhesive is 70% or less. When the gel fraction is 70% or less, the embossed shape is easily transferred to the adhesive surface of the first adhesive layer 31. Moreover, it becomes easy to fill the groove | channel formed in the 1st adhesive layer 31 by the press of the adhesive sheet 1 stuck on the to-be-adhered body. From this viewpoint, the gel fraction of the pressure-sensitive adhesive is preferably 60% or less, and particularly preferably 50% or less. In addition, the measuring method of a gel fraction is as showing to the below-mentioned test example.

  Although the adhesive which comprises the 1st adhesive layer 31 of the adhesive sheet 1 which concerns on this embodiment will not be specifically limited if said physical property is satisfy | filled, it is preferable that it is an adhesive containing a polyrotaxane compound. The polyrotaxane compound has a mechanical bond between a cyclic molecule and a linear molecule penetrating the cyclic molecule, and the cyclic molecule can freely move on the linear molecule. Due to the sliding effect based on such a structure, the resulting pressure-sensitive adhesive exhibits high stress relaxation properties and a plastic effect, and can improve cohesion by blending many cross-linking agents described later while maintaining high adhesive strength. It becomes possible. Therefore, the pressure-sensitive adhesive containing the polyrotaxane compound easily satisfies the physical properties described above. Thereby, the 1st adhesive layer 31 comprised with the said adhesive can become the thing excellent in emboss shape transferability, the uneven | corrugated shape maintenance property at the time of sticking, the uneven | corrugated shape disappearance after sticking, and durability. .

  As a kind of adhesive which comprises the 1st adhesive layer 31, any of acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone adhesives etc., for example Good. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be either a crosslinked type or a non-crosslinked type. Among them, an acrylic pressure-sensitive adhesive that easily satisfies the above-described physical properties and is excellent in adhesive physical properties is preferable.

  In addition, the acrylic pressure-sensitive adhesive may be active energy ray-curable or non-active energy ray-curable, but in order to effectively exhibit the action of the polyrotaxane compound, It is preferable that the active energy ray is non-curable. As the active energy ray non-curable acrylic pressure-sensitive adhesive, a cross-linking type is particularly preferable, and a thermal cross-linking type is more preferable.

  In particular, the pressure-sensitive adhesive according to this embodiment is a pressure-sensitive adhesive composition (hereinafter referred to as “pressure-sensitive adhesive composition”) containing a (meth) acrylic acid ester polymer (A), a crosslinking agent (B), and a polyrotaxane compound (C). It is preferable that it is an adhesive (adhesive formed by crosslinking the adhesive composition P). With such an adhesive, the above-described physical properties are easily satisfied, and since excellent adhesive force and predetermined cohesive force are exhibited, the durability is also excellent. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

(1) Component (1-1) (meth) acrylic acid ester polymer (A) of adhesive composition P
The (meth) acrylic acid ester polymer (A) in the present embodiment includes a reactive group-containing monomer having in its molecule a reactive group that reacts with the crosslinking agent (B) as a monomer unit constituting the polymer. It is preferable. The reactive group derived from the reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and an adhesive having a desired cohesive force is obtained.

  Examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Etc.) are preferred. Among these, a hydroxyl group-containing monomer that is excellent in reactivity with the crosslinking agent (B) and has little adverse effect on the adherend is particularly preferable.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. And 4-hydroxybutyl (meth) acrylate is preferred, and 2-hydroxyethyl (meth) acrylate is particularly preferred. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 0.5% by mass or more of a reactive group-containing monomer as a lower limit value as a monomer unit constituting the polymer, and contains 1% by mass or more. It is more preferable to contain 8 mass% or more, and it is more preferable to contain 12 mass% or more. The (meth) acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as an upper limit of 30% by mass or less, particularly 25% by mass or less, as the monomer unit constituting the polymer. It is preferable to contain, Furthermore, it is preferable to contain 20 mass% or less. When the (meth) acrylic acid ester polymer (A) contains a reactive group-containing monomer in the above amount as a monomer unit, the resulting pressure-sensitive adhesive is good through the crosslinking agent (B) and the polyrotaxane compound (C). A crosslinked structure is formed, and the above-described relaxation elastic modulus G (300) and gel fraction are easily satisfied.

  The (meth) acrylic acid ester polymer (A) preferably contains (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer. Thereby, favorable adhesiveness can be expressed. The alkyl group may be linear or branched.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group from the viewpoint of adhesiveness. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the tackiness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferred, methyl (meth) acrylate, n-butyl (meth) acrylate and (meth) acrylic. 2-ethylhexyl acid is particularly preferable, and 2-ethylhexyl (meth) acrylate is more preferable. In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) preferably contains 30% by mass or more, particularly 40% by mass or more, of (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer. More preferably, it is preferable to contain 50% by mass or more. When the lower limit value of the content of the (meth) acrylic acid alkyl ester is as described above, the (meth) acrylic acid ester polymer (A) can exhibit suitable tackiness. The (meth) acrylic acid ester polymer (A) preferably contains 99% by mass or less, and 97% by mass or less of (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer. Is more preferable, and it is particularly preferable to contain 95% by mass or less, and more preferably 70% by mass or less. When the upper limit of the content of the (meth) acrylic acid alkyl ester is as described above, a suitable amount of other monomer components such as a reactive functional group-containing monomer is introduced into the (meth) acrylic acid ester polymer (A). be able to.

  The (meth) acrylic acid ester polymer (A) preferably also contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the alicyclic structure-containing monomer in the polymer increases the distance between the polymers, and the resulting pressure-sensitive adhesive can be made excellent in flexibility. . Thereby, it becomes easy to reduce the relaxation elastic modulus G (300) of the obtained adhesive.

  The carbocyclic ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond in part. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. From the viewpoint of making the distance between the obtained (meth) acrylic acid ester polymer (A) appropriate and imparting high stress relaxation properties to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure ( A polycyclic structure). Furthermore, considering the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, from the viewpoint of imparting stress relaxation properties as described above, the carbon number of the alicyclic structure (refers to the total number of carbon atoms of the portion forming the ring, and when multiple rings exist independently) , Which means the total number of carbon atoms) is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but it is preferably 15 or less and particularly preferably 10 or less from the viewpoint of compatibility as described above.

  Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylic. Dicyclopentenyl acid, dicyclopentenyloxyethyl (meth) acrylate, and the like, among others, (meth) acrylic acid dicyclopentanyl (carbon number of alicyclic structure) that exhibits better step following ability 10), adamantyl (meth) acrylate (carbon number of alicyclic structure: 10) or isobornyl (meth) acrylate (carbon number of alicyclic structure: 7) is preferable, and isobornyl (meth) acrylate is particularly preferable. . These may be used individually by 1 type and may be used in combination of 2 or more type.

  When the (meth) acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it preferably contains 1% by mass or more of the alicyclic structure-containing monomer. In particular, the content is preferably 5% by mass or more, more preferably 10% by mass or more. In addition, the (meth) acrylic acid ester polymer (A) preferably contains 30% by mass or less of the alicyclic structure-containing monomer as a monomer unit constituting the polymer, particularly 25% by mass or less. It is preferable to contain 20% by mass or less. When the content of the alicyclic structure-containing monomer is in the above range, the relaxation elastic modulus G (300) is easily lowered to some extent while maintaining the gel fraction of the obtained pressure-sensitive adhesive to be high to some extent.

  Moreover, it is also preferable that the said (meth) acrylic acid ester polymer (A) contains a nitrogen atom containing monomer as a monomer unit which comprises the said polymer. By having a nitrogen atom-containing monomer as a structural unit in the polymer, the pressure-sensitive adhesive is given a predetermined polarity, and it has excellent affinity for adherends having a certain degree of polarity. it can. As the nitrogen atom-containing monomer, a monomer having a nitrogen-containing heterocyclic ring is preferable from the viewpoint of giving the (meth) acrylate polymer (A) an appropriate rigidity.

  Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholine exhibiting more excellent adhesive strength is preferable, and N-acryloylmorpholine is particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type.

  When the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the nitrogen atom-containing monomer is preferably contained in an amount of 1% by mass or more, particularly 2% by mass. % Or more, preferably 3% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 20% by mass or less of the nitrogen atom-containing monomer as a monomer unit constituting the polymer, and particularly 15% by mass or less. More preferably, the content is preferably 10% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the obtained pressure-sensitive adhesive can exhibit more excellent adhesion to stainless steel and the like.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group in order not to inhibit the above-described action of the reactive functional group-containing monomer. Examples of such a monomer include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) is preferably a linear polymer. By being a linear polymer, entanglement of molecular chains is likely to occur, and an improvement in cohesive force can be expected. Therefore, it is easy to increase the gel fraction to a predetermined level while keeping the relaxation elastic modulus G (300) low. .

  The (meth) acrylic acid ester polymer (A) is preferably a solution polymer obtained by a solution polymerization method. By being a solution polymer, it becomes easy to obtain a high molecular weight polymer, and an improvement in cohesive force can be expected. Therefore, a pressure-sensitive adhesive that easily maintains the uneven shape is easily obtained.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 or more as a lower limit, particularly preferably 300,000 or more, and more preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not less than the above, it is easy to increase the gel fraction of the obtained pressure-sensitive adhesive.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 2 million or less as an upper limit, particularly preferably 1.5 million or less, and more preferably 1 million or less. preferable. When the upper limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, it becomes easy to suppress the relaxation elastic modulus G (300) of the obtained pressure-sensitive adhesive. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

(1-2) Crosslinking agent (B)
The cross-linking agent (B) can cross-link the (meth) acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P and can satisfactorily form a three-dimensional network structure. Thereby, it becomes easy to satisfy | fill the gel fraction mentioned above in the adhesive obtained.

  As said crosslinking agent (B), what is necessary is just to react with the reactive group which (meth) acrylic acid ester polymer (A) has, for example, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, and an amine type crosslinking agent , Melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Is mentioned. Among these, when the reactive group of the (meth) acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that is excellent in reactivity with the hydroxyl group. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

  The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). The amount is preferably 05 parts by mass or more, and more preferably 0.1 parts by mass or more. Further, the content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and further preferably 0.4 parts by mass or less. When the content of the crosslinking agent (B) is in the above range, the above-described relaxation elastic modulus G (300) and gel fraction are more easily satisfied in the obtained pressure-sensitive adhesive.

(1-3) Polyrotaxane compound (C)
The polyrotaxane compound (C) is a compound in which a linear molecule penetrates through openings of at least two cyclic molecules and has a blocking group at both ends of the linear molecule. In this polyrotaxane compound (C), the cyclic molecule can freely move on the linear molecule, but the cyclic molecule has a structure in which the cyclic molecule cannot escape from the linear molecule due to the blocking group. That is, the linear molecule and the cyclic molecule maintain their forms while exhibiting a sliding effect by a so-called mechanical bond rather than a chemical bond such as a covalent bond. When the pressure-sensitive adhesive (pressure-sensitive adhesive composition P) according to the present embodiment contains the polyrotaxane compound (C) having such a mechanical bond, the pressure-sensitive adhesive obtained has the above-described relaxation elastic modulus G (300) and gel. It becomes easy to satisfy the fraction. Thereby, the 1st adhesive layer 31 comprised with the said adhesive can become the thing excellent in emboss shape transferability, the uneven | corrugated shape maintenance property at the time of sticking, the uneven | corrugated shape disappearance after sticking, and durability. .

  In particular, when the cyclic molecule of the polyrotaxane compound (C) is a cyclic oligosaccharide having a hydroxyl group as a reactive group, when the isocyanate crosslinking agent is used as the crosslinking agent (B), the isocyanate crosslinking agent is used. (Meth) acrylic acid ester polymer (A) and polyrotaxane compound (C) (cyclic molecule thereof) are cross-linked, and the cyclic molecule freely moves on the linear molecule in polyrotaxane compound (C). As a result, the flexibility as a crosslinked body is remarkably improved while maintaining a high cohesive force. As a result, the obtained pressure-sensitive adhesive easily satisfies the above-described relaxation elastic modulus G (300) and gel fraction.

  The polyrotaxane compound (C) in the present embodiment preferably has a cyclic oligosaccharide as a cyclic molecule. By using a cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (C), it becomes possible to select an appropriate ring diameter, and thereby the effect due to the movement of the cyclic molecule on the linear molecule is easily exhibited. Moreover, when the said cyclic oligosaccharide has a hydroxyl group as a reactive group, reaction with an isocyanate type crosslinking agent is easy. Furthermore, introduction of various substituents and the like is easy, whereby the compatibility between the polyrotaxane compound (C) and other components can be adjusted by the polyrotaxane compound (C). Furthermore, if it is cyclic oligosaccharide, there also exists an advantage that acquisition is easy. In the present specification, “cyclic” of “cyclic molecule” or “cyclic oligosaccharide” means substantially “cyclic”. In other words, the cyclic molecule may not be completely closed as long as it can move on the linear molecule, and may have a helical structure, for example.

  Preferred cyclic oligosaccharides include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and among them, α-cyclodextrin is particularly preferable. Two or more kinds of cyclic molecules of the polyrotaxane compound (C) may be mixed in the polyrotaxane compound (C) or in the adhesive (adhesive composition P).

  When the cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (C) has a hydroxyl group as a reactive group, the hydroxyl group may be a hydroxyl group that the cyclic oligosaccharide originally has (refers to a state before modification). Further, it may be a hydroxyl group introduced as a substituent into the cyclic oligosaccharide.

  The lower limit of the hydroxyl value of the cyclic molecule is preferably 10 mgKOH / g or more, more preferably 30 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. A polyrotaxane compound (C) can fully react with an isocyanate type crosslinking agent as the lower limit of a hydroxyl value is more than the above. In addition, the upper limit of the hydroxyl value of the cyclic molecule is preferably 1000 mgKOH / g or less, more preferably 200 mgKOH / g or less, and particularly preferably 100 mgKOH / g or less. When the upper limit of the hydroxyl value exceeds the above value, a large number of crosslinks occur in the same cyclic molecule, so that the cyclic molecule itself becomes a crosslink point, and the effect of the crosslink point as the whole polyrotaxane compound (C) can be exhibited. As a result, a desired relaxation modulus may not be achieved with the resulting pressure-sensitive adhesive.

  The linear molecule of the polyrotaxane compound (C) is a molecule or substance that is included in a cyclic molecule and can be integrated by a mechanical bond rather than a chemical bond such as a covalent bond. If it is, it will not be specifically limited. In the present specification, “linear” of “linear molecule” means substantially “linear”. That is, the linear molecule may have a branched chain as long as the cyclic molecule can move on the linear molecule.

  As the linear molecule of the polyrotaxane compound (C), for example, polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylate, polydimethylsiloxane, polyethylene, polypropylene and the like are preferable. Two or more kinds of linear molecules may be mixed in the adhesive composition P.

  The number average molecular weight of the linear molecule of the polyrotaxane compound (C) is preferably 3,000 or more as a lower limit, particularly preferably 10,000 or more, and more preferably 20,000 or more. preferable. When the lower limit of the number average molecular weight is not less than the above, the amount of movement of the cyclic molecule on the linear molecule is secured, and the stress relaxation property of the pressure-sensitive adhesive is sufficiently obtained. The number average molecular weight of the linear molecule of the polyrotaxane compound (C) is preferably 300,000 or less, particularly preferably 200,000 or less, more preferably 100,000 or less, as an upper limit. It is preferable. When the upper limit of the number average molecular weight is not more than the above, the solubility of the polyrotaxane compound (C) in the solvent and the compatibility with the (meth) acrylic acid ester polymer (A) are improved.

  The blocking group of the polyrotaxane compound (C) is not particularly limited as long as the cyclic molecule is a group capable of maintaining a form in which the cyclic molecule is skewered with a linear molecule. Examples of such groups include bulky groups and ionic groups.

  Specifically, the blocking group of the polyrotaxane compound (C) may be a dinitrophenyl group, a cyclodextrin, an adamantane group, a trityl group, a fluorescein, a pyrene, an anthracene, or the like, or a number average molecular weight of 1,000. A main chain or side chain of a polymer of ˜1,000,000 is preferable, and two or more of these blocking groups may be mixed in the polyrotaxane compound (C) or the adhesive composition P.

  The polyrotaxane compound (C) described above can be obtained by a conventionally known method (for example, a method described in JP-A-2005-154675).

  Content of the polyrotaxane compound (C) in the adhesive composition P which concerns on this embodiment is 0.1 mass part or more as a lower limit with respect to 100 mass parts of (meth) acrylic acid ester polymers (A). It is preferably 1 part by mass, more preferably 1 part by mass or more, and further preferably 5 parts by mass or more. When the lower limit value of the content of the polyrotaxane compound (C) is as described above, the relaxation elastic modulus G (300) is easily lowered to a predetermined extent without lowering the gel fraction of the obtained pressure-sensitive adhesive. Further, the content of the polyrotaxane compound (C) is preferably 50 parts by mass or less, more preferably 25 parts by mass or less, and particularly preferably 10 parts by mass or less as an upper limit. When the upper limit value of the content of the polyrotaxane compound (C) is as described above, the cohesive strength of the pressure-sensitive adhesive obtained by securing the contents of the (meth) acrylic acid ester polymer (A) and the crosslinking agent (B) and The adhesive strength can be further improved.

(1-4) Various Additives For the adhesive composition P, if necessary, various additives usually used for acrylic adhesives, for example, antistatic agents, tackifiers, antioxidants, light stabilizers. , Softeners, fillers and the like can be added. The polymerization solvent and dilution solvent described later are not included in the additive constituting the adhesive composition P.

  In addition, since the 1st adhesive layer 31 formed from the adhesive composition P can exhibit favorable adhesive force even if it is a thin film, the necessity for adding a tackifier is low.

(2) Manufacture of adhesive composition P The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), the obtained (meth) acrylic acid ester polymer (A), and a crosslinking agent. While mixing (B) and a polyrotaxane compound (C), it can manufacture by adding an additive depending on necessity.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  Once the (meth) acrylic acid ester polymer (A) is obtained, the solution of the (meth) acrylic acid ester polymer (A) is added to the crosslinking agent (B), the polyrotaxane compound (C), and optionally additives and dilutions. The adhesive composition P (coating solution) diluted with the solvent is obtained by adding the solvent and mixing thoroughly.

  When any of the above components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, the component is used alone as a dilution solvent. It may be dissolved or diluted and then mixed with other components.

  Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-60 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as a dilution solvent.

(3) Production of pressure-sensitive adhesive The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 31 in the present embodiment is preferably formed by crosslinking the pressure-sensitive adhesive composition P. The crosslinking of the pressure-sensitive adhesive composition P can be usually performed by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing a dilution solvent etc. from the coating film of the adhesive composition P apply | coated to the desired target object.

  The heating temperature of the heat treatment is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

  After the heat treatment, it is preferable to provide a curing period of about 1 to 2 weeks at normal temperature (for example, 23 ° C., 50% RH). By providing this curing period, the crosslinking reaction is almost completely completed, and an adhesive having a high cohesive force is formed.

  By the heat treatment and curing described above, a pressure-sensitive adhesive in which the (meth) acrylic acid ester polymer (A) is sufficiently crosslinked through the crosslinking agent (B) and the polyrotaxane compound (C) to form a crosslinked structure is obtained. . Such a pressure-sensitive adhesive has excellent stress relaxation properties and high cohesive force, whereby the aforementioned relaxation elastic modulus G (300) and gel fraction are easily satisfied.

(4) Thickness of the pressure-sensitive adhesive layer The thickness of the first pressure-sensitive adhesive layer 31 in the pressure-sensitive adhesive sheet 1 according to this embodiment (value measured according to JIS K7130) is 1 μm or more, as described above, and is 2 μm. It is preferable that it is above, and it is preferable that it is 4 micrometers or more especially. When the thickness of the 1st adhesive layer 31 is 1 micrometer or more, it becomes what was excellent in emboss shape transferability.

  Further, as described above, the thickness of the first pressure-sensitive adhesive layer 31 is 14 μm or less, preferably 12 μm or less, particularly preferably 10 μm or less, and further preferably 8 μm or less. When the thickness of the first pressure-sensitive adhesive layer 31 is as described above, the heat conduction from the adherend to the graphite sheet or the like can be made more efficient.

(5) Shape of pressure-sensitive adhesive surface In the first pressure-sensitive adhesive layer 31 in the present embodiment, the first release sheet 41 having a concavo-convex shape on the release surface is provided on the first pressure-sensitive adhesive layer 31 side. It is laminated so that it may be located in. Thereby, the recessed part of the shape corresponding to the uneven | corrugated shaped convex part in the peeling surface of the 1st peeling sheet 41 is formed in the adhesion surface of the 1st adhesive layer 31, and, therefore, the 1st adhesive layer 31 is adhesive. The surface has an uneven shape.

  The uneven shape of the first pressure-sensitive adhesive layer 31 on the pressure-sensitive adhesive surface is such that the air trapped between the pressure-sensitive adhesive surface and the adherend during sticking is released to the outside of the pressure-sensitive adhesive sheet 1 and the adhesion. It is preferable to have a convex part for adhering to the body and ensuring a predetermined adhesive force.

  In addition, as shown in FIG. 1, the non-contact part U may exist between the peeling surface of the 1st peeling sheet 41 and the 1st adhesive layer 31. As shown in FIG. In the example shown in FIG. 1, the front end surface (lower end surface in FIG. 1) of the convex portion 51 of the adhesive surface in the first adhesive layer 31 and the bottom surface of the concave portion in the release surface of the first release sheet 41. There is a gap between them, and the gap is a non-contact portion U. Thus, the non-contact part U exists between the peeling surface of the first release sheet 41 and the first pressure-sensitive adhesive layer 31, thereby peeling the first release sheet 41 from the first pressure-sensitive adhesive layer 31. It is possible to easily peel the first release sheet 41 without reducing the peeling force when doing so and without damaging the uneven shape formed on the first pressure-sensitive adhesive layer 31. However, the present invention is not limited to the above configuration, and the adhesive surface (irregularity) of the first adhesive layer 31 and the peeling surface (irregularity) of the first release sheet 41 are closely adhered. You may do it.

  Even when the non-contact portion U exists as described above, the first pressure-sensitive adhesive layer 31 is preferably formed integrally without being divided at the concave portion. By having such a configuration, when the first release sheet 41 is peeled from the first pressure-sensitive adhesive layer 31, chipping or breakage of the first pressure-sensitive adhesive layer 31 can be prevented.

  A plan view showing an example of the adhesive surface of the first adhesive layer 31 is shown in FIG. On the adhesive surface of the first pressure-sensitive adhesive layer 31 in the present embodiment, a plurality of convex portions 51 having a regular triangle in plan view and a groove-like concave portion 52 located between the convex portions 51 are formed. . The plurality of convex portions 51 are alternately formed so that adjacent equilateral triangular convex portions 51 are in an upside-down relationship with each other.

  The planar view shape of the convex portion 51 is not limited to a regular triangle, and may be an arbitrary triangle, an arbitrary polygon such as a quadrangle, a hexagon, an octagon, or a circle. Any shape such as a shape, an elliptical shape, and an infinity shape may be used. Among these, a polygonal shape that allows the contact area of the convex portion 51 with respect to the adherend to be large is preferable because the shape of the concave portion 52 in a plan view is linear.

  The lower limit value of the depth of the recess 52 is preferably 0.1 μm or more, particularly preferably 1 μm or more, and more preferably 2 μm or more. Since the lower limit of the depth of the recess 52 is as described above, when the adhesive sheet 1 is pasted, the air between the adhesive surface of the first adhesive layer 31 and the adherend is discharged through the recess 52. It is easy to be done, and it is possible to satisfactorily secure the air escape property through the recess 52. On the other hand, the upper limit value of the depth of the recess 52 is preferably 12 μm or less, particularly preferably 10 μm or less, and more preferably 6 μm or less. When the upper limit value of the depth of the concave portion 52 is as described above, it is possible to prevent the graphite sheet from dropping at the concave portion 52 after being stuck and deteriorating the appearance of the graphite sheet.

  The cross-sectional shape (side view shape) of the recess 52 is not particularly limited, and may be, for example, a rectangle, a V shape, or a U shape.

  The lower limit value of the width of the recess 52 is preferably 10 μm or more, particularly preferably 30 μm or more, and more preferably 50 μm or more. Since the lower limit value of the width of the recess 52 is as described above, the air between the adhesive surface of the first adhesive layer 31 and the adherend is discharged through the recess 52 when the adhesive sheet 1 is pasted. It is easy to ensure good air escape properties through the recess 52. On the other hand, the upper limit value of the width of the recess 52 is preferably 200 μm or less, particularly preferably 150 μm or less, and more preferably 100 μm or less. When the upper limit value of the width of the concave portion 52 is the above, it is possible to prevent the graphite sheet from dropping at the concave portion 52 after pasting and deteriorating the appearance of the graphite sheet.

  In the adhesive surface of the first pressure-sensitive adhesive layer 31, it is preferable that the recess 52 exists in a circle having an arbitrary diameter of 0.5 to 2.0 mm, and particularly in an circle having an arbitrary diameter of 0.5 to 1.5 mm. It is preferable that the recess 52 exists in the surface, and it is further preferable that the recess 52 exists in a circle having an arbitrary diameter of 0.5 to 1.0 mm. Thereby, when sticking the adhesive sheet 1, the air between the adhesive surface of the first adhesive layer 31 and the adherend is easily discharged through the recess 52, and the air release property through the recess 52 is improved. It can be ensured satisfactorily.

  In addition, it is preferable that the said groove-shaped recessed part 52 in the adhesive surface of the 1st adhesive layer 31 is extended to the edge part of the planar direction of the adhesive sheet 1 from a viewpoint of air bleeding property, and each recessed part. Although it is preferable that 52 is mutually continuous, it is not limited to these.

  The lower limit of the area ratio of the convex portions 51 on the adhesive surface of the first adhesive layer 31 is preferably 75% or more, particularly preferably 80% or more, and more preferably 85% or more. preferable. When the lower limit of the area ratio of the convex part 51 is the above, the contact area of the 1st adhesive layer 31 and a to-be-adhered body is ensured, and sufficient adhesive force can be obtained. On the other hand, the upper limit of the area ratio of the convex portions 51 on the adhesive surface of the first adhesive layer 31 is preferably 99% or less, particularly preferably 97% or less, and more preferably 95% or less. It is preferable. When the upper limit value of the area ratio of the convex portion 51 is as described above, the area ratio of the concave portion 52 can be secured, and the air escape effect by the concave portion 52 can be sufficiently obtained.

  When the planar view shape of the convex portion 51 is a regular triangle as shown in FIG. 2, the length of one side of the regular triangle is preferably 800 μm or more, particularly preferably 900 μm or more, It is preferable that it is 1000 micrometers or more. Further, the length of one side of the equilateral triangle is preferably 4000 μm or less, particularly preferably 3000 μm or less, and further preferably 2000 μm or less. When the length of one side of the equilateral triangle is within the above range, it is possible to achieve both cohesion and air bleeding at a higher level.

(6) Physical properties (6-1) Adhesive force immediately after application The adhesive force immediately after applying the adhesive sheet 1 according to the present embodiment to stainless steel (SUS304 # 600) is 0.5 N / 25 mm or more as a lower limit. In particular, it is preferably 1.0 N / 25 mm or more, and more preferably 1.5 N / 25 mm or more. When the adhesive strength of the pressure-sensitive adhesive sheet 1 is 0.5 N / 25 mm or more, it becomes easy to satisfy the durability assumed under the usage environment of the graphite sheet. On the other hand, the upper limit value of the adhesive strength is preferably 15 N / 25 mm or less, more preferably 12.5 N / 25 mm or less, and particularly preferably 10 N / 25 mm or less in consideration of re-sticking. In addition, the adhesive force in this specification means the adhesive force measured by the 180 degree | times peeling method according to JISZ0237: 2009 fundamentally, and a specific test method is as showing in the test example mentioned later. .

(6-2) Adhesive strength 24 hours after application The adhesive strength 24 hours after application of the adhesive sheet 1 according to the present embodiment to stainless steel (SUS304 # 600) is 4.0 N / 25 mm as a lower limit. In particular, it is preferably 6.0 N / 25 mm or more, and more preferably 8.0 N / 25 mm or more. When the pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet 1 is 4.0 N / 25 mm or more, it becomes easy to satisfy the durability assumed under the usage environment of the graphite sheet. On the other hand, the upper limit value of the adhesive strength is not particularly limited, but is preferably 40 N / 25 mm or less, more preferably 30 N / 25 mm or less, and particularly preferably 20 N / 25 mm or less.

1-3. 1st release sheet The 1st release sheet 41 in this embodiment has the uneven | corrugated shape which can transfer the uneven | corrugated shape mentioned above to the adhesive surface of the said 1st adhesive layer 31 formed in the release surface. Yes. Specifically, the release surface of the first release sheet 41 has a concave portion having a shape corresponding to the convex portion 51 of the adhesive surface in the first adhesive layer 31 and an adhesive in the first adhesive layer 31. A convex portion having a shape portion corresponding to the concave portion 52 of the surface is formed.

  The 1st peeling sheet 41 will not be specifically limited if the above uneven | corrugated shapes are formed in the peeling surface. The first release sheet 41 may be composed only of a release substrate having releasability, but in order for the release surface having a concavo-convex shape to exhibit good releasability, the release substrate and at least the release substrate It is preferable to include a release agent layer formed on one surface side.

  Examples of the release substrate include a paper substrate, a laminated paper obtained by laminating a thermoplastic resin on a paper substrate, a plastic film, a nonwoven fabric, a metal foil, or a laminated sheet containing these.

  Among these, as the peeling substrate, a laminated paper that easily forms an uneven shape by embossing is preferable, and a laminated paper in which a thermoplastic resin is laminated on both sides of the paper substrate is particularly preferable. By laminating the thermoplastic resin on both sides of the paper base material, the moisture resistance of the paper base material is improved, and a low-cost base material with excellent performance can be obtained.

  Examples of the paper substrate include glassine paper, coated paper, cast coated paper, dust-free paper, and high-quality paper. Among these, glassine paper is preferable from the viewpoint of easy formation of the uneven shape by embossing.

  The thickness of the paper substrate is preferably 40 μm or more, particularly preferably 80 μm or more, and more preferably 100 μm or more. Further, the thickness of the paper substrate is preferably 500 μm or less, particularly preferably 400 μm or less, and further preferably 300 μm or less. When the thickness of the paper substrate is within the above range, the first release sheet 41 can more easily form an uneven shape by embossing.

  Examples of the thermoplastic resin to be laminated on the paper substrate include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, and polystyrene. Among these, polyolefin is preferable from the viewpoint of easy formation of the uneven shape by embossing, and polyethylene is particularly preferable.

  The thickness of the laminate layer made of a thermoplastic resin is preferably 10 μm or more, particularly preferably 15 μm or more, and more preferably 20 μm or more. The thickness of the laminate layer is preferably 100 μm or less, particularly preferably 70 μm or less, and more preferably 50 μm or less. When the thickness of the laminate layer is within the above range, the uneven shape can be more easily formed on the laminate layer by embossing.

  There is no restriction | limiting in particular as release agent which comprises a release agent layer, Arbitrary things can be suitably selected and used from conventionally well-known things. Examples of such release agents include silicone resin, fluororesin, alkyd resin, olefin resin, acrylic, long chain alkyl group-containing compound, unsaturated polyester resin, rubber, and wax. Examples of the release agent include silicone resin-based release agents from the viewpoint of cost and releasability.

  The thickness of the release agent layer is preferably 10 nm or more, particularly preferably 30 nm or more, and further preferably 50 nm or more. Further, the thickness of the release agent layer is preferably 1000 nm or less, particularly preferably 500 nm or less, and further preferably 300 nm or less. When the thickness of the release agent layer is within the above range, the function as the release agent layer can be sufficiently exerted, and the release agent layer is formed without filling the recesses in the uneven surface of the release substrate. be able to.

  Examples of the method for forming the uneven shape on the release surface of the first release sheet 41 include embossing, laser processing, and bite processing. Among these, embossing is preferable because of the ease of forming the uneven shape.

  When forming an uneven | corrugated shape in the peeling surface of the 1st peeling sheet 41 by embossing, it is preferable to perform embossing with respect to the peeling base material before forming a release agent layer. Thereby, it is possible to prevent the release agent layer from being detached from the release substrate by embossing.

  Embossing prepares the embossing roll which has the uneven | corrugated shape to form in the adhesive surface of the 1st adhesive layer 31, and the said embossing roll is the one side (1st release sheet 41 of the peeling base material of the 1st peeling sheet 41). Can be carried out by press-contacting to the surface of the release surface and transferring the uneven shape onto the release substrate.

  The lower limit of the height of the convex portion on the release surface of the first release sheet 41 is preferably 0.1 μm or more, particularly preferably 2 μm or more, more preferably 8 μm or more, Is preferably 15 μm or more. By setting the lower limit value of the height of the convex portion as described above, the concave portion 52 having the preferable depth described above can be reliably formed on the adhesive surface of the first pressure-sensitive adhesive layer 31. Moreover, when the height of the convex part in the peeling surface of the 1st peeling sheet 41 is larger than the thickness of the 1st adhesive layer 31, the non-contact part U mentioned above is formed.

  On the other hand, the upper limit of the height of the convex portion on the release surface of the first release sheet 41 is preferably 50 μm or less, particularly preferably 40 μm or less, and more preferably 30 μm or less. When the upper limit value of the height of the convex portion is as described above, it is possible to achieve both the transferability of the embossed shape and the suitability for sticking to the pressure-sensitive adhesive surface.

  The width of the convex portion and the planar shape of the concave portion on the release surface of the first release sheet 41 correspond to the width of the concave portion 52 and the planar shape of the convex portion 51 on the adhesive surface of the first pressure-sensitive adhesive layer 31.

1-4. Second pressure-sensitive adhesive layer As the type of pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 32, a desired pressure-sensitive adhesive force is exerted on the adherend of the second pressure-sensitive adhesive layer 32, particularly a graphite sheet. If it exists, it will not specifically limit, For example, any of an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, a silicone adhesive, etc. may be sufficient. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be either a crosslinked type or a non-crosslinked type. Among them, an acrylic pressure-sensitive adhesive having excellent pressure-sensitive physical properties is preferable.

  The acrylic pressure-sensitive adhesive may be active energy ray curable or non-active energy ray curable. However, the active energy ray non-curable is easy to handle. It is preferable that. As the active energy ray non-curable acrylic pressure-sensitive adhesive, a cross-linking type is particularly preferable, and a thermal cross-linking type is more preferable.

  It is preferable that the adhesive which comprises the 2nd adhesive layer 32 is an adhesive formed by bridge | crosslinking the adhesive composition containing a (meth) acrylic acid ester polymer and a crosslinking agent especially.

  The thickness of the second pressure-sensitive adhesive layer 32 is preferably 0.5 μm or more, particularly preferably 1.0 μm or more, and further preferably 1.5 μm or more. Thereby, the 2nd adhesive layer 32 can exhibit favorable adhesive force. The thickness of the second pressure-sensitive adhesive layer 32 is preferably 14 μm or less, more preferably 12 μm or less, particularly preferably 10 μm or less, and further preferably 4 μm or less. Thereby, the graphite sheet laminated body mentioned later can be formed thinly.

1-5. Second Release Sheet The second release sheet 42 is not particularly limited, and a conventionally known one can be used. However, since the second release sheet 42 is usually peeled before the first release sheet 41 when the pressure-sensitive adhesive sheet 1 is used, it is preferable that the peel strength is smaller than that of the first release sheet 41.

  As this 2nd peeling sheet 42, what formed the release agent layer in the single side | surface of a plastic film can be used preferably, for example. As the release agent constituting the kind of the plastic film and the release agent layer, those exemplified in the first release sheet 41 can be used.

  Although there is no restriction | limiting in particular about the thickness of the 2nd peeling sheet 42, Usually, it is about 20-150 micrometers.

1-6. Thickness as double-sided pressure-sensitive adhesive sheet Thickness of pressure-sensitive adhesive sheet 1 (excluding release sheets 41 and 42) as double-sided pressure-sensitive adhesive sheet, in this embodiment, first pressure-sensitive adhesive layer 31, substrate 2 and second pressure-sensitive adhesive The lower limit of the thickness of the laminate comprising the layer 32 is preferably 2 μm or more, particularly preferably 3.5 μm or more, and more preferably 5 μm or more. When the lower limit value of the thickness of the laminate is as described above, the handleability becomes easy.

  On the other hand, the upper limit of the thickness of the laminate is preferably 40 μm or less, more preferably 30 μm or less, particularly preferably 20 μm or less, and further preferably 12 μm or less. When the upper limit value of the thickness of the laminate is as described above, a graphite sheet laminate described later can be thinly formed.

2. Manufacture of an adhesive sheet As one manufacture example of the adhesive sheet 1, the case where the said adhesive composition P is used for formation of the 1st adhesive layer 31 is demonstrated.

  Initially, the laminated body of the base material 2, the 2nd adhesive layer 32, and the 2nd peeling sheet 42 is manufactured. This laminate may be manufactured by forming the second pressure-sensitive adhesive layer 32 on the release surface of the second release sheet 42 and then laminating the base material 2 on the second pressure-sensitive adhesive layer 32. Then, the second pressure-sensitive adhesive layer 32 may be formed on one surface of the substrate 2, and the second release sheet 42 may be laminated on the second pressure-sensitive adhesive layer 32.

  Next, the coating liquid of the adhesive composition P is apply | coated to the surface on the opposite side to the 2nd adhesive layer 32 side in the base material 2 of the laminated body obtained above. As a coating method, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

  Thereafter, the coating solution of the applied adhesive composition P is subjected to heat treatment to thermally crosslink the adhesive composition P to form an application layer. Then, after a curing period, the first pressure-sensitive adhesive layer 31 before the formation of the concavo-convex shape is formed. The conditions for the heat treatment and curing are as described above. During the curing period, it is preferable to protect the coating layer with a desired release sheet. This release sheet is peeled off before the first release sheet 41 is laminated on the first pressure-sensitive adhesive layer 31.

  Next, the release surface of the first release sheet 41 is brought into contact with the surface (adhesive surface) on the side opposite to the substrate 2 in the first adhesive layer 31 (before formation of the concavo-convex shape). 41 is pressed against the first pressure-sensitive adhesive layer 31. Thereby, the convex part of the uneven | corrugated shape in the peeling surface of the 1st peeling sheet 41 is embedded in the 1st adhesive layer 31, and the recessed part of the shape corresponding to the said convex part is the adhesive surface of the 1st adhesive layer 31 Formed. Accordingly, an uneven shape is formed on the adhesive surface of the first adhesive layer 31. In this way, the pressure-sensitive adhesive sheet 1 is obtained.

  In addition, even if it is a case where the height of the convex part of the peeling surface of the 1st release sheet 41 is larger than the thickness of the 1st adhesive layer 31, the 1st release sheet with respect to the 1st adhesive layer 31 As long as 41 is pressed under normal pressure, the first pressure-sensitive adhesive layer 31 is usually formed integrally without being divided by the recess 52.

3. Use of pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet 1 according to the present embodiment can be suitably used as a double-sided pressure-sensitive adhesive sheet for bonding a graphite sheet to an electronic component, but is not limited thereto. For example, it can be used for fixing automobile parts, electronic parts, product name display labels, wallpaper sticking, and the like.

[Graphite sheet laminate]
As shown in FIG. 3, the graphite sheet laminated body 6 which concerns on one Embodiment of this invention is formed by laminating | stacking the graphite sheet 61 instead of the 2nd peeling sheet 42 in the adhesive sheet 1 mentioned above. That is, in the graphite sheet laminate 6 according to the present embodiment, the graphite sheet 61, the second pressure-sensitive adhesive layer 32, the substrate 2, the first pressure-sensitive adhesive layer 31, and the first release sheet 41 are included. Are stacked in that order.

  The graphite sheet 61 is a member excellent in heat dissipation, and is preferably used to radiate heat generated from electronic components constituting the electronic device in electronic devices such as smartphones, tablet terminals, and personal computers. The material of the graphite sheet 61 is not particularly limited, and may be a conventionally known material.

  The thickness of the graphite sheet 61 is preferably 100 μm or less, particularly preferably 30 μm or less, as an upper limit value in an electronic device that is required to be thin. The lower limit of the thickness is usually 5 μm or more, preferably 10 μm or more.

  In addition, you may laminate | stack a desired layer, for example, a colored sheet, on the surface (surface on the opposite side to the 2nd adhesive layer 32 side) of the graphite sheet 61. FIG.

  In order to manufacture the graphite sheet laminate 6, the second release sheet 42 may be peeled from the pressure-sensitive adhesive sheet 1 described above, and the exposed second pressure-sensitive adhesive layer 32 may be attached to the graphite sheet 61.

  The graphite sheet laminate 6 can be used by being attached to a desired electronic component via the first pressure-sensitive adhesive layer 31. Examples of electronic components include components that generate heat, such as batteries, CPUs, power devices, and high-intensity LEDs.

  When affixing the graphite sheet laminate 6 to an adherend (electronic component), first, the first release sheet 41 is peeled from the first pressure-sensitive adhesive layer 31 of the graphite sheet laminate 6. Here, the first pressure-sensitive adhesive layer 31 is integrally formed, and there is a non-contact portion U between the release surface of the first release sheet 41 and the first pressure-sensitive adhesive layer 31. Therefore, the first release sheet 41 can be easily peeled from the first pressure-sensitive adhesive layer 31 without impairing the uneven shape formed on the first pressure-sensitive adhesive layer 31.

  Next, the graphite sheet laminate 6 is gradually pressed against the adherend from one end so that the exposed adhesive surface of the first adhesive layer 31 is in close contact with the adherend. At this time, the air between the adherend and the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer 31 passes through the recess 52 in the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer 31, and the first pressure-sensitive adhesive layer 31 is still It is discharged in the direction not in close contact with the adherend. Therefore, it is difficult for air to be caught between the adherend and the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer 31, and it is possible to suppress the accumulation of air. When the concave portion 52 of the adhesive surface of the first pressure-sensitive adhesive layer 31 extends to the end portion of the graphite sheet laminate 6 in the plane direction, even if air is trapped and an air pocket is created, By recompressing the air reservoir portion or the peripheral portion of the air reservoir portion including the air reservoir portion, air escapes from the recess 52 to the outside of the graphite sheet laminate 6, and the air reservoir disappears.

  Moreover, in discharging the air between the adherend and the adhesive surface of the first pressure-sensitive adhesive layer 31, the graphite sheet laminate 6 is pressed against the adherend. As a result, the concave portion 52 of the adhesive surface of the first adhesive layer 31 is filled, and the uneven shape of the adhesive surface almost disappears. Thereby, there is almost no gap between the first pressure-sensitive adhesive layer 31 and the adherend. Due to the appropriate cohesive force of the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 31 and the above-described structure, the graphite sheet laminate 6 is excellent in durability assumed in its use environment.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, the 2nd peeling sheet 42 in the adhesive sheet 1 may be abbreviate | omitted, and also the 2nd adhesive layer 32 may be abbreviate | omitted. On the other hand, the first release sheet 41 may be peeled and removed as long as the first pressure-sensitive adhesive layer 31 is formed with a concavo-convex shape. Thereafter, the normal release sheet is the first pressure-sensitive adhesive layer 31. May be laminated. Moreover, the 1st peeling sheet 41 in the graphite sheet laminated body 6 may be replaced by another peeling sheet. Furthermore, the height of the convex part on the peeling surface of the first release sheet 41 is smaller than the thickness of the first pressure-sensitive adhesive layer 31, whereby there is no non-contact part U, and the first pressure-sensitive adhesive layer The pressure-sensitive adhesive surface 31 (irregularities thereof) and the release surface (irregularities thereof) of the first release sheet 41 may be closely adhered.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of single-sided pressure-sensitive adhesive sheet 95.5 parts by weight of butyl acrylate, 3 parts by weight of vinyl acetate, 1 part by weight of 2-hydroxyethyl acrylate, and 0.5 parts by weight of acrylic acid were used to copolymerize the weight average. An acrylic ester copolymer having a molecular weight of 1,000,000 was prepared.

  Next, hydrogenated rosin ester (made by Arakawa Chemical Industries, product name “Pine Crystal KE-100”, softening point: 100 ° C. with respect to 100 parts by mass (converted to solid content; the same applies hereinafter) of the acrylic ester copolymer. ) 25 parts by mass, polymerized rosin ester (Arakawa Chemical Industries, product name “Pencel D-135”, softening point: 135 ° C.) and petroleum resin (Mitsui Chemicals, product name “FTR6100”, softening) Point: 95 ° C.) 24 parts by mass was added and mixed to obtain an adhesive component. The adhesive component was dissolved in toluene to prepare an adhesive solution having a solid content concentration of 13% by mass. To the pressure-sensitive adhesive solution, 1.07 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem, product name “BHS8515”) as a crosslinking agent is added, and a pressure-sensitive adhesive composition solution (solid content concentration: 13% by mass) is added. Obtained.

  Thereafter, the above-mentioned adhesive was applied to the release-treated surface of a release sheet (second release sheet; manufactured by Lintec Corporation, product name “SP-PLS 381021”, thickness 38 μm) on which one side of the polyethylene terephthalate film was released with a silicone-based release agent. The adhesive composition solution was applied and dried to form a 2 μm thick adhesive layer (second adhesive layer). Next, a polyethylene terephthalate film (product name “PET 2 F51L”, thickness 2 μm, manufactured by Toray Industries, Inc.) as a base material is bonded to the adhesive layer, and the base material / second adhesive layer / second release is bonded. A single-sided PSA sheet consisting of a sheet was obtained.

2. Preparation of the first release sheet Glassine paper (made by Lintec Co., Ltd., product name “Maru K Genshiro 110.0G”, thickness 110 μm) on both sides of polyethylene (medium density polyethylene (density 0.93 g / cm) ³ )) was laminated to prepare a laminated paper having a 20 μm thick polyethylene layer on both sides of the paper substrate.

  On the other hand, an engraved metal roll (metal roll made of steel, diameter: 30 cm) having an uneven shape as shown in FIG. Specifically, on the surface of the embossing roll, a plurality of regular triangles having a side of 1 mm in plan view are formed as convex portions, and a gap portion between the convex portions is formed as a groove-shaped concave portion having a width of 70 μm and a depth of 20 μm. Has been. The plurality of regular triangular convex portions are alternately formed so that the convex portions of adjacent regular triangles are in an upside-down relationship.

  By passing the laminated paper prepared above between the embossing roll and the silicone rubber roll, the polyethylene layer on one side of the laminated paper is embossed, and the uneven shape (embossed shape) of the embossing roll is applied to the polyethylene layer. Transcribed to. Then, a silicone release agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name “KS-847H”) is applied to the surface of the polyethylene layer to which the concavo-convex shape (embossed shape) has been transferred, and then dried to remove 50 nm in thickness. An agent layer was formed to obtain a first release sheet. The height of the concavo-convex convex portion on the release surface of the obtained first release sheet was 20 μm.

3. Preparation of (meth) acrylic acid ester polymer (A) 65 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate, 5 parts by mass of 4-acryloylmorpholine and 15 parts by mass of 2-hydroxyethyl acrylate (Meth) acrylic acid ester polymer (A). When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, the weight average molecular weight (Mw) was 500,000.

4). Preparation of Adhesive Composition 100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained above, and trimethylolpropane-modified tolylene diisocyanate (product name “BHS8515, manufactured by Toyochem Co., Ltd.) as a crosslinking agent (B) ”) 0.25 parts by mass, polyrotaxane compound (C) (manufactured by Advanced Soft Materials, product name“ Celum Superpolymer SH3700P ”, linear molecule: polyethylene glycol, cyclic molecule: hydroxypropyl group and caprolactone chain Α-cyclodextrin having, blocking group: adamantane group, weight average molecular weight (Mw) 700,000, hydroxyl value 72 mg KOH / g) 7.5 parts by mass, mixed well, and diluted with ethyl acetate A coating solution of the adhesive composition was obtained.

5. Manufacture of an adhesive sheet The coating solution of the adhesive composition obtained above was apply | coated with the knife coater on the base material of the single-sided adhesive sheet mentioned above. And the application layer was heat-processed at 90 degreeC for 1 minute (s), and the application layer was formed.

  Subsequently, the light-release type release sheet (product name “SP-PET 382120”, manufactured by Lintec Corporation) obtained by releasing a coating layer of the pressure-sensitive adhesive composition and one side of the polyethylene terephthalate film with a silicone-based release agent is used. The first pressure-sensitive adhesive layer having a thickness of 6 μm was formed by pasting so that the release-treated surface of the release sheet was in contact with the coating layer and curing for 7 days under the conditions of 23 ° C. and 50% RH. Thereby, the laminated body which consists of a 2nd peeling sheet / a 2nd adhesive layer / base material / a 1st adhesive layer (uneven | corrugated shape unformed) / lightly peeling type release sheet was obtained. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

Finally, the light release type release sheet is peeled from the laminate, and the release surface on which the uneven shape (embossed shape) of the first release sheet is formed is brought into contact with the exposed adhesive surface of the first adhesive layer. The first release sheet was pressed against the first pressure-sensitive adhesive layer for 3 days under a load of 16 g / cm ² in an environment of 23 ° C. and 50% RH. And the convex part of the uneven | corrugated shape (embossed shape) in the peeling surface of a 1st peeling sheet is embedded in a 1st adhesive layer, and the recessed part of the shape corresponding to the said convex part is used for the adhesive surface of a 1st adhesive layer. Formed. In this way, an uneven shape is formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet (second release sheet / second pressure-sensitive adhesive layer / base material / first pressure-sensitive adhesive layer / first A release sheet) was obtained.

[Example 2]
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the addition amount of the crosslinking agent (B) was changed to 0.15 parts by mass. .

Example 3
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the addition amount of the crosslinking agent (B) was changed to 0.1 parts by mass. .

[Comparative Example 1]
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the polyrotaxane compound (C) was not added.

[Comparative Example 2]
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the crosslinking agent (B) was not added.

[Comparative Example 3]
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, Examples were made except that the polyrotaxane compound (C) was not added and the addition amount of the crosslinking agent (B) was changed to 0.10 parts by mass. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

[Comparative Example 4]
In the preparation of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer, Examples were made except that the polyrotaxane compound (C) was not added and the addition amount of the crosslinking agent (B) was changed to 0.05 parts by mass. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

[Reference example]
In the same manner as in Example 1, a laminate composed of the second release sheet / second pressure-sensitive adhesive layer / base material / first pressure-sensitive adhesive layer (unformed uneven shape) / light release type release sheet was produced, This was used as an adhesive sheet. That is, in Example 1, the pressure-sensitive adhesive sheet was obtained by replacing the light release type release sheet of the laminate with the first release sheet.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of relaxation modulus)
In the laminate composed of the second release sheet / second adhesive layer / base material / first adhesive layer (unformed unevenness) / light release release sheet prepared in Examples, Comparative Examples and Reference Examples A plurality of first pressure-sensitive adhesive layers were laminated to form a laminate having a thickness of 1 mm. A cylindrical body having a diameter of 8 mm (height of 1 mm) was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

Using the viscoelasticity measuring device (product name “MCR300”, manufactured by Anton paar), the above-mentioned sample was distorted with the adhesive under the following conditions to measure the relaxation elastic modulus G in accordance with JIS K7244-1. The relaxation elastic modulus G (300) (Pa) with a relaxation time of 300 seconds was obtained. The results are shown in Table 1.
Measurement temperature: 23 ° C
Strain: 10%
Measurement points: 1000 points (logarithmic plot)

[Test Example 2] (Measurement of gel fraction)
A laminate composed of the second release sheet / second pressure-sensitive adhesive layer / base material / first pressure-sensitive adhesive layer (unformed uneven shape) / light release type release sheet prepared in Examples, Comparative Examples and Reference Examples By cutting into a size of 80 mm × 80 mm, wrapping the first pressure-sensitive adhesive layer in a polyester mesh (mesh size 200), weighing the mass with a precision balance, and subtracting the mass of the mesh alone, the pressure-sensitive adhesive Only the mass was calculated. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 1.

[Test Example 3] (Evaluation of emboss shape transferability)
The first release sheet was peeled off from the pressure-sensitive adhesive sheets produced in Examples, Comparative Examples and Reference Examples, and the exposed pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer was subjected to a confocal microscope (product name “HD100D”, manufactured by Leathertech Co., Ltd.). (Magnification: 20 times) was observed, and it was confirmed whether or not an uneven shape (embossed shape) was formed on the adhesive surface. And emboss shape transferability was evaluated based on the following criteria. The results are shown in Table 1.
○: The uneven shape was accurately formed.
X: Uneven shape was not formed.

  Moreover, while observing the adhesive surface of a 1st adhesive layer similarly to the above, calculating the area ratio (%) of the convex part in the adhesive surface of a 1st adhesive layer, It was confirmed whether or not there was a recess in an arbitrary 1 mm circle on the adhesive surface. The results are shown in Table 1.

  In addition, on the adhesive surface of the first adhesive layer in the adhesive sheet manufactured in the example, as shown in FIG. 2, a plurality of planar regular triangles having a side of 1 mm are formed as convex portions, and the gap portions thereof Was formed as a groove-like recess having a width of 70 μm and a depth of 4 μm.

[Test Example 4] (Evaluation of air release properties)
The pressure-sensitive adhesive sheets produced in Examples, Comparative Examples and Reference Examples were cut into a size of 6 cm × 6 cm, and this was used as a sample. Samples were prepared for each 5 samples. Next, each sample was affixed to a 7 cm × 7 cm glass plate so that an air pocket remained in the center of the sample. Thereafter, the air reservoir was pressed with a finger to check whether the air reservoir disappeared. And the air release property was evaluated based on the following criteria. The results are shown in Table 1.
A: The air pocket completely disappeared in all five samples.
A: Air pockets completely disappeared in 2 to 4 samples out of 5 samples.
Δ: The air pocket completely disappeared in only one of the five samples.
X: Air pockets remained in all five samples.

[Test Example 5] (Measurement of adhesive strength)
The pressure-sensitive adhesive sheets produced in Examples, Comparative Examples and Reference Examples were cut into 25 mm width and 100 mm length. In an environment of 23 ° C. and 50% RH, the first release sheet was peeled from the pressure-sensitive adhesive sheet, and the exposed first pressure-sensitive adhesive layer was attached to a stainless steel plate (SUS304, # 600). At this time, it was stuck by pressurizing one reciprocating pressure-sensitive adhesive sheet with a 2 kg roller. Tensile tester (Orientec Co., Tensilon) shows the adhesive strength (N / 25mm) immediately after application and the adhesive strength (N / 25mm) after standing for 24 hours under the conditions of 23 ° C and 50% RH. Was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Conditions other than those described here were measured according to JIS Z0237: 2009. The results are shown in Table 1.

[Test Example 6] (Evaluation of adhesiveness of graphite sheet laminate)
The pressure-sensitive adhesive sheets produced in Examples, Comparative Examples and Reference Examples were cut into 50 mm × 100 mm. The second release sheet was peeled from this adhesive sheet, and the exposed second adhesive layer was attached to a 48 mm × 98 mm graphite sheet (manufactured by Selen, product name “SGS-025-APH”, thickness 25 μm). . Next, a 50 mm × 100 mm black colored sheet (manufactured by Lintec, product name “MO-P001-5V2”, thickness 5 μm) was attached to the surface of the graphite sheet, and this was used as a graphite sheet laminate. The graphite sheet laminate was prepared in 5 samples for each example.

The first release sheet was peeled from the resulting graphite sheet laminate, and the exposed first pressure-sensitive adhesive layer was attached to a stainless steel (SUS304) housing. And the external appearance after sticking was confirmed visually and the sticking property of the graphite sheet laminated body was evaluated based on the following criteria. The results are shown in Table 1.
A: All five samples had good appearance without air accumulation.
A: 2 to 4 samples out of 5 samples were free from air accumulation and had a good appearance.
Δ: Only one of the five samples had a good appearance without air accumulation.
X: All five samples had air pockets and had poor appearance.

[Test Example 7] (Evaluation of durability)
The sample of each example 1 whose appearance was good among the bonded body of the graphite sheet laminate and the stainless steel produced in Test Example 6 was put into a dry condition at 80 ° C. for 500 hours. Then, after cooling to normal temperature, durability was evaluated based on the following criteria. Note that Comparative Examples 1 to 3 and Reference Example were not evaluated because Test Example 6 was not good in appearance.
◯: There was no foaming or peeling, and a good appearance was maintained.
X: Foaming or peeling was confirmed, and a good appearance was not maintained.

  As can be seen from Table 1, the graphite sheet laminate using the pressure-sensitive adhesive sheet of the example was excellent in emboss shape transferability in the first pressure-sensitive adhesive layer. In addition, the graphite sheet laminates according to the examples exhibited good air release properties at the time of sticking, and were excellent in the sticking properties of the graphite sheet laminates. Furthermore, the graphite sheet laminates according to the examples were excellent in durability.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used as a double-sided pressure-sensitive adhesive sheet for graphite sheets.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 2 ... Base material 31 ... 1st adhesive layer 32 ... 2nd adhesive layer 41 ... 1st peeling sheet 42 ... 2nd peeling sheet 51 ... Convex part 52 ... Concave part 6 ... Graphite sheet lamination | stacking Body 61 ... Graphite sheet U ... Non-contact part

Claims (13)

A pressure-sensitive adhesive sheet comprising a base material and a first pressure-sensitive adhesive layer laminated on one surface side of the base material,
The substrate has a thickness of 0.5 μm or more and 15 μm or less,
The thickness of the first pressure-sensitive adhesive layer is 1 μm or more and 14 μm or less,
The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer has a relaxation elastic modulus G (300) after 300 seconds at 23 ° C. of 1000 Pa to 2500 Pa, and a gel fraction of 30% to 70%. A pressure-sensitive adhesive sheet.   The pressure-sensitive adhesive sheet according to claim 1, wherein an uneven shape is formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer.   A release sheet having an uneven shape on the release surface is laminated so that the release surface is located on the side of the first pressure-sensitive adhesive layer on the side opposite to the base material in the first pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein:   The pressure-sensitive adhesive sheet according to claim 3, wherein a convex portion having a height of 0.1 μm or more and 50 μm or less is formed on the release surface of the release sheet.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer contains a polyrotaxane compound.   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein a second pressure-sensitive adhesive layer is laminated on the other surface side of the base material.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the thickness of the second pressure-sensitive adhesive layer is 1 µm or more and 8 µm or less.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which is attached to a graphite sheet. On one surface side of the substrate, a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive having a relaxation elastic modulus G (300) after 300 seconds of 23 ° C. of 1000 Pa to 2500 Pa and a gel fraction of 30% or more, Formed after a curing period,
Next, the pressure-sensitive adhesive sheet manufacturing method comprising contacting the pressure-sensitive adhesive layer with the pressure-sensitive adhesive layer, and pressing the pressure-sensitive adhesive layer against the pressure-sensitive adhesive layer. Graphite sheet,
A graphite sheet laminate comprising a first pressure-sensitive adhesive layer provided on one surface side of the graphite sheet,
The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer has a relaxation elastic modulus G (300) after 300 seconds at 23 ° C. of 1000 Pa to 2500 Pa, and a gel fraction of 30% or more. Graphite sheet laminate.   A release sheet having a concavo-convex release surface is laminated so that the first adhesive layer is opposite to the graphite sheet and the release surface is positioned on the first adhesive layer side. The graphite sheet laminate according to claim 11, wherein:   Between the graphite sheet and the first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer located on the graphite sheet side and a base material located on the first pressure-sensitive adhesive layer side are interposed. The graphite sheet laminate according to claim 11 or 12, wherein:

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