JP2015071727A - Adhesive film for processing graphite sheet, and heat radiation sheet product on which the adhesive film is adhered - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film for processing use for protecting graphite sheet that radiates heat generated from electronic components, and a heat radiation sheet product on which the adhesive film is adhered.SOLUTION: An adhesive agent layer 2 formed on a surface of a film substrate 1 contains (meth)acrylic polymer with (meth)acrylic monomer having carbon numbers 1 to 18 of an alkyl group as a main component, and contains a fatty acid ester compound as a plasticizer. In this occasion, it is preferable that the fatty acid ester compound be contained at 10 to 70 pts.wt. with respect to 100 pts.wt. of the (meth)acrylic polymer, and butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate, or the like is preferable.

Description

  The present invention is applied to a graphite sheet laminate (having a structure in which a protective adhesive film is attached to the surface of a graphite sheet) for dissipating heat generated from an electronic component provided in an electronic device such as a mobile phone. The present invention relates to an adhesive film (adhesive film for processing a graphite sheet) to be used.

In an electronic device such as a mobile phone, a heat radiating sheet has been used as a cooling means for radiating heat generated from an electronic component provided inside, and as the heat radiating sheet, the thermal conductivity in the surface direction is high. Graphite sheets are generally used. However, the graphite sheet is fragile and has poor processability such as a punching process and a cutting process. There is a problem that the graphite sheet is easily broken when the adhesive tape is forcibly peeled off.
Therefore, in order to solve such a problem, for example, in Patent Document 1 below, an adhesive tape having a predetermined adhesive force and having an adhesive layer provided on the back side of the thin film film substrate is used as a graphite sheet. A pressure-sensitive adhesive tape for a heat-dissipating sheet has been disclosed which has improved workability by preventing the occurrence of cracks when manufacturing a heat-dissipating sheet, and the generation of bubbles and wrinkles.

  However, in the case of the heat-dissipating sheet pressure-sensitive adhesive tape described in Patent Document 1, there has been devised to stick a strong-adhesive protective adhesive film on one side of the graphite sheet, but the surface of the graphite sheet is a rough surface, so the surface is a film In order to cover with, it can respond only with the adhesive film using the thin film film base material of 2-8 micrometers thickness with good followability, and was not enough for prevention of the brittle fracture of a graphite sheet.

JP 2010-254979 A

The present invention solves the above-mentioned problems in the prior art, and provides a pressure-sensitive adhesive film that is less susceptible to brittle fracture of the graphite sheet during molding such as punching and cutting, and has good wettability, workability, and peelability. The task is to do. Moreover, the subject of this invention is also providing the heat-radiation sheet product to which the said adhesive film was affixed.
In order to solve the above problems, the present inventors have a thickness of 30 to 100 μm on the surface of the protective adhesive film in the graphite sheet laminate in which a strong adhesive protective adhesive film is adhered to one side of the above-described graphite sheet. As a result of laminating a pressure-sensitive adhesive film using a thick film base material and conducting various studies on the properties of the pressure-sensitive adhesive layer for graphite sheet processing, a fatty acid ester as a plasticizer is added to a pressure-sensitive adhesive component made of a (meth) acrylic polymer. When using a pressure-sensitive adhesive with added, it is possible to improve workability and peelability when sticking to the surface of a graphite sheet laminate, and to effectively prevent brittle fracture of the graphite sheet during punching and cutting. As a result, the present invention was completed.

  The pressure-sensitive adhesive film for processing a graphite sheet of the present invention capable of solving the above-mentioned problems is for protecting a graphite sheet that dissipates heat generated from parts of an electronic device, and is a surface of a film substrate constituting the pressure-sensitive adhesive film Is provided with a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive, and the pressure-sensitive adhesive mainly comprises a (meth) acrylic monomer having an alkyl group having 1 to 18 carbon atoms as a pressure-sensitive adhesive component. And a (meth) acrylic polymer and a fatty acid ester compound.

  Further, the present invention provides the pressure-sensitive adhesive film for processing a graphite sheet having the above characteristics, wherein the fatty acid ester compound is contained in an amount of 10 to 70 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. It is a feature.

  Moreover, the present invention is characterized in that in the pressure-sensitive adhesive film for processing a graphite sheet having the above-mentioned characteristics, the fatty acid ester compound has a molecular weight of 100 to 2,000.

  Further, the present invention provides the graphite sheet processing adhesive film having the above characteristics, wherein the fatty acid ester compound is at least selected from the group consisting of butyl laurate, butyl stearate, isopropyl myristate, and isopropyl palmitate. It is also characterized by being one or more types.

  Furthermore, the present invention provides the graphite sheet processing pressure-sensitive adhesive film having the above-described features, wherein the film base has a thickness of 30 to 100 μm, and the pressure-sensitive adhesive layer has a pressure-sensitive adhesive force of 0.001 to 0.05 N / 25 mm. It is characterized by being.

  Further, in the heat radiation sheet product of the present invention, the graphite sheet processing adhesive film having the above-described characteristics is attached to the surface of the graphite sheet laminate in which the protective adhesive film is attached to the surface of the graphite sheet. It is characterized by that.

  With the pressure-sensitive adhesive film for processing a graphite sheet of the present invention, brittle fracture of the graphite sheet during molding such as punching or cutting can be prevented. Further, the surface of the thin film protective adhesive film adhered to the surface of the graphite sheet has a gentle cubic surface reflecting the rough surface state of the graphite surface. In the pressure-sensitive adhesive, since the wettability of the pressure-sensitive adhesive is improved by adding the fatty acid ester compound to the pressure-sensitive adhesive, it is possible to improve the workability (air release property) and the peelability when sticking. In addition, when the adhesive film of the present invention is used, it is possible to prevent the generation of bubbles and wrinkles at the time of punching and cutting and the interlayer breakage of the graphite sheet.

It is a figure which shows the laminated constitution of the adhesive film for graphite sheet processing which concerns on embodiment of this invention, and the release liner 3 is laminated | stacked in order to protect the surface of the adhesive layer 2 provided in the single side | surface of the film base material 1 ing. An example of a heat radiation sheet product of the present invention having a layer structure in which a graphite sheet 6 having a thin film (about 6 to 12 μm) protective adhesive film 5 attached to the surface is attached to an adhesive film 4 for processing a graphite sheet is shown. FIG. 2 is a cross-sectional configuration diagram, and a double-sided tape 7 and a separator (release processing film) 8 are laminated on the back side of the graphite sheet 6.

Hereinafter, the details of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pressure-sensitive adhesive film for processing a graphite sheet of the present invention comprises a film base 1 and a pressure-sensitive adhesive layer 2 provided on one surface of the film base 1. Although it does not specifically limit about the material of the base material 1, A polyethylene terephthalate (PET) film is preferable from the point of transparency and adhesiveness with the adhesive which comprises an adhesive layer. The thickness of the film substrate 1 in the present invention is generally about 30 to 100 μm, and preferably about 50 to 75 μm. In this case, the surface of the film substrate 1 on the pressure-sensitive adhesive layer 2 side is adhesive. Corona treatment may be performed for the purpose of increasing the adhesive strength with the agent layer 2.

  In the present invention, as shown in FIG. 1, the release liner 3 is generally laminated on the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive layer 2, and the release liner 3 is separated from the surface. A release-treated PET film coated with a mold is common. Moreover, it is preferable that the antistatic layer is formed in the surface side of the film base material 1 by coating with an antistatic agent.

Although the adhesive layer 2 in the adhesive film of this invention is formed by apply | coating an adhesive to the surface of the film base material 1, as an adhesive for forming the adhesive layer 2, C1-C18 A (meth) acrylic polymer mainly composed of an acrylic monomer having an alkyl group and / or a methacrylic monomer is used, and such a polymer has excellent transparency and durability.
Examples of the monomer constituting the (meth) acrylic polymer particularly preferable in the present invention include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylate-n-propyl, ( Examples include isopropyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylexyl (meth) acrylate, and these may be used alone or in combination of two or more.
A crosslinking agent may be used, and suitable crosslinking agents include, for example, isocyanate crosslinking agents, epoxy crosslinking agents, chelate crosslinking agents, and the like. As addition amount of a crosslinking agent, it is 0.1-5.0 weight part with respect to 100 weight part of (meth) acrylic-type polymers, Preferably it is 0.5-4.0 weight part, More preferably, it is 1.0-3.0. It mix | blends in the ratio of a weight part. It is also possible to increase the amount of crosslinking agent added to lower the adhesive strength, but at that time the wettability of the adhesive also decreases, making it difficult to stick to the rough surface of the graphite sheet, or zipping This is not preferable because it causes breakage of the graphite sheet.

In the present invention, various commercially available products can be used as the fatty acid ester compound added to the pressure-sensitive adhesive layer 2, but suitable compounds are fatty acid ester compounds having a molecular weight of 100 to 2000, such as butyl laurate and stearin. Particularly preferred are butyl acid, isopropyl myristate, and isopropyl palmitate. Under the present circumstances, these compounds may be added independently and 2 or more types may be added. The molecular weight of the fatty acid ester compound is limited to the above range. If the molecular weight is less than 100, bleeding tends to occur because the molecular weight is small. Conversely, if the molecular weight exceeds 2000, the molecular weight is large. This is because the compound becomes a solid and handling properties are deteriorated.
In the present invention, the fatty acid ester compound is blended in an amount of 10 to 70 parts by weight, preferably 20 to 60 parts by weight, more preferably 30 to 50 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. Is done.

  In order to form the pressure-sensitive adhesive layer 2 in the present invention, the above-mentioned compounds are blended at a predetermined ratio to prepare the pressure-sensitive adhesive of the present invention, which is dissolved in a suitable solvent to form a pressure-sensitive adhesive solution. It forms on a base material by various coating methods. At this time, the coating method of the pressure-sensitive adhesive solution is not particularly limited, and various known coating methods can be used. For example, a die coater, a comma coater, a knife coater, a gravure coater, a roll coater, or the like can be used. In the present invention, the thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is applied so that the film thickness after drying is 5 to 100 μm, preferably 10 to 25 μm.

The adhesive film for processing a graphite sheet of the present invention having the adhesive layer 2 formed by coating the adhesive to which the fatty acid ester compound is added as a plasticizer has an adhesive strength of the adhesive layer 2 of 0.001. It is preferable to be within a range of ˜0.05 N / 25 mm, and by using such an adhesive force, brittle fracture of the graphite sheet at the time of punching or cutting can be effectively prevented, and after the above processing, it is appropriate. Can be peeled off with force. At this time, if the adhesive strength of the adhesive layer 2 is less than 0.001 N / 25 mm, the adhesive strength is weak, and the adhesive film may peel off from the thin film protective adhesive film on the surface of the graphite sheet. If it exceeds 25 mm, it is difficult to easily peel off from the graphite sheet laminate, and there is a risk of interlayer breakage of the graphite sheet. In the present invention, the range of the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer 2 is more preferably 0.005 to 0.04 N / 25 mm, and most preferably 0.009 to 0.03 N / 25 mm.
The adhesive strength of the pressure-sensitive adhesive layer 2 in the present invention is a value measured according to JIS Z0237: 2000. When measuring the adhesive strength, first, the sample is cut into a size of 25 mm × 150 mm, Affixed to an adherend (glass plate or PET film), pressure-bonded once with a 2 kg rubber roller, and after 1 minute and 24 hours, the adhesive strength is measured using a tensile tester (unit: N / 25 mm). The measurement conditions at this time are 180 ° peeling, 23 ° C./50% RH, and a peeling speed of 300 mm / min.

FIG. 2 is a diagram showing a cross-sectional configuration of an example of a heat dissipation sheet product to which the above-described pressure-sensitive adhesive film for processing a graphite sheet of the present invention is attached for the purpose of protecting the graphite sheet. In the heat dissipation sheet product of FIG. Is the surface of the graphite sheet laminate formed by adhering the protective adhesive film 5 to the surface of the graphite sheet 6, the adhesive film 4 for processing a graphite sheet of the present invention is adhered, and on the back side of the graphite sheet 6, A double-sided tape (double-sided pressure-sensitive adhesive sheet) 7 and a separator (release processing film) 8 are laminated. The protective adhesive film 5 in FIG. 2 is generally a strongly adhesive thin count PET sheet (PET adhesive film of 6 to 12 μm).
Specific examples of the present invention are shown in the following examples, but the present invention is not limited thereto.

[Production Example of Adhesive Film for Processing Graphite Sheet of the Present Invention]
First, as a pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer, an acrylic pressure-sensitive adhesive (a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 18 carbon atoms as a main component (100 weight) Part)) as a main agent, and 2.0 parts by weight of an isocyanate-based cross-linking agent is added thereto, and the adhesive has an adhesive strength in the range of 0.05 to 0.5 N / 25 mm with respect to the SUS adherend. ), And to this pressure-sensitive adhesive, commercially available isopropyl myristate is added in an amount ranging from 10 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer, and the pressure-sensitive adhesive layer A forming coating solution was obtained. On the other hand, a commercially available PET film having a thickness of 50 μm (PET film manufactured by Toyobo Co., Ltd., trade name: Cosmo Shine (registered trademark) A4300) was prepared as a film substrate.
Then, the coating liquid is coated on one side of the film base so that the thickness of the pressure-sensitive adhesive layer after drying is 20 μm, and the pressure-sensitive adhesive layer is formed by drying, and the graphite sheet processing of the present invention An adhesive film was prepared.

  Similarly, as a comparative example, without adding isopropyl myristate, the acrylic pressure-sensitive adhesive was coated and dried to prepare a pressure-sensitive adhesive film. When 60 parts by weight of isopropyl myristate was added to 100 parts by weight of the acrylic polymer, the pressure-sensitive adhesive gelled.

About the adhesive film of this invention obtained above and the adhesive film of a comparative example, the adhesive force with respect to a glass plate and the adhesive force with respect to a PET film (125 micrometers in thickness) were measured with the following method, respectively.
The adhesive strength was measured according to JIS Z0237: 2000.
First, the measurement sample (adhesive film) is cut to a size of 25 mm x 150 mm, bonded to an adherend (glass plate or PET film), and then pressed once with a 2 kg rubber roller, after 1 minute and 24 hours, respectively. The adhesive strength was measured using a tensile tester (unit: N / 25 mm). The measurement conditions at this time were 180 ° peeling, 23 ° C. and 50% RH, and a peeling speed of 300 mm / min.

In addition, the pressure-sensitive adhesive film of the present invention and the pressure-sensitive adhesive film of Comparative Example were each bonded to a commercially available graphite sheet laminate (the surface of a graphite sheet having a thickness of about 70 to 100 μm, and a protective pressure-sensitive adhesive film having a thickness of 12 μm or less was adhered to the surface. And the laminated sheet obtained is punched and cut, and visually observed for the presence or absence of delamination or delamination and the occurrence of partial lifting of the laminate. The graphite sheet molding processability was evaluated. In Table 1 below, x indicates a state of interlaminar fracture or delamination (interlaminar fracture refers to a fracture occurring in a graphite sheet, which is a laminate of expanded graphite), and Δ indicates wetness. It indicates that air does not come out due to poor performance and that the laminate is partially lifted, and ◯ indicates that the workability and the moldability are good.
The results obtained by the above measurement and observation are shown in Table 1 below.

As shown in Table 1 above, the pressure-sensitive adhesive film for processing a graphite sheet of the present invention provided with a pressure-sensitive adhesive layer containing a specific amount of a fatty acid ester compound has an appropriate pressure-sensitive adhesive force. When pasting and cutting, the graphite sheet does not break or crack, and it is difficult to cause interlaminar fracture or lamination failure, and it is confirmed that the workability and moldability are good. It was.
In addition, the pressure-sensitive adhesive film of the present invention was good in terms of wettability and air detachability when adhered to the surface of the graphite sheet laminate.

  Furthermore, when butyl laurate, butyl stearate, and isopropyl palmitate are added in the same amount as the fatty acid ester compound instead of isopropyl myristate, the same good results as isopropyl myristate are obtained. Obtained.

  The pressure-sensitive adhesive film of the present invention is useful as a film for processing a graphite sheet that dissipates heat generated from electronic components in electronic devices such as mobile phones.

DESCRIPTION OF SYMBOLS 1 Film base material 2 Adhesive layer 3 Release liner (release processing film)
4 Adhesive film for processing graphite sheet 5 Protective adhesive film (Thin count PET adhesive sheet)
6 Graphite sheet 7 Double-sided tape 8 Separator

Claims (6)

  An adhesive film used to protect a graphite sheet that dissipates heat generated from parts of an electronic device, and is formed by coating an adhesive on the surface of a film substrate constituting the adhesive film A pressure-sensitive adhesive layer is provided, and the pressure-sensitive adhesive contains a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 18 carbon atoms as a main component, and A pressure-sensitive adhesive film for processing a graphite sheet, comprising a fatty acid ester compound.   The pressure-sensitive adhesive film for processing a graphite sheet according to claim 1, wherein the fatty acid ester compound is contained in an amount of 10 to 70 parts by weight based on 100 parts by weight of the (meth) acrylic polymer.   The pressure-sensitive adhesive film for processing a graphite sheet according to claim 1 or 2, wherein the fatty acid ester compound has a molecular weight of 100 to 2,000.   4. The fatty acid ester compound according to claim 1, wherein the fatty acid ester compound is at least one selected from the group consisting of butyl laurate, butyl stearate, isopropyl myristate, and isopropyl palmitate. 2. An adhesive film for processing a graphite sheet according to 1.   The thickness of the said film base material is 30-100 micrometers, and the adhesive force of the said adhesive layer is 0.001-0.05N / 25mm, The any one of Claims 1-4 characterized by the above-mentioned. Adhesive film for processing graphite sheets.   The graphite sheet processing adhesive film according to any one of claims 1 to 5 is attached to the surface of a graphite sheet laminate in which a protective adhesive film is attached to the surface of the graphite sheet. Heat dissipation sheet product.

Images