JP2015067736A - Method for thermoconductive rubber sheet and thermoconductive rubber sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a thermoconductive rubber sheet difficult to be fixed to a heat generator and a radiator and capable of comparatively easily being peeled after use and to provide a thermoconductive rubber sheet produced by the production method.SOLUTION: The method for producing a thermoconductive rubber sheet comprises: a first crosslinking step of molding a thermoconductive resin composition containing a crosslinkable component and a thermoconductive filler under heating to produce a sheet-like molded product having at least partially crosslinked crosslinkable component; and a surface treatment step of contacting at least a part of the surface of the sheet-like molded product with a fluorine-based silane coupling agent. The thermoconductive rubber sheet is produced by the production method.

Description

  The present invention is a method for producing a thermally conductive rubber sheet used as a sheet or the like that is interposed between a heating element and a radiator and efficiently conducts heat of the heating element to the radiator, and The present invention relates to a thermally conductive rubber sheet obtained by the production method.

  Thermally conductive rubber between a heat generating body such as an electronic component and a heat radiating body (a heat radiating member or a cooling member) as a means for efficiently releasing heat generated inside various devices and electronic devices to the outside Conventionally, a sheet is arranged. By interposing a heat conductive rubber sheet having a good heat conduction performance, the heat conduction efficiency from the heating element to the heat radiating body can be improved.

  Although it is a heat conductive sheet made of silicone rubber containing silicon as a main component, which is currently on the market, a fluororubber-based heat conductive sheet has also been proposed in recent years (for example, Patent Document 1).

JP 2010-232535 A

  The heat conductive rubber sheet is required to have good heat conduction efficiency, but it does not adhere strongly to the heating element and heat radiator that are in contact with each other during use, and it is relatively easy to peel off even after use. We need to be able to do it. In particular, in the case of applying a heat conductive rubber sheet to a semiconductor manufacturing apparatus, even if a slight amount of contaminants are mixed, the yield and operation reliability of the semiconductor device can be greatly affected. If this happens, it is necessary to spend a great deal of labor and cost on the work for completely washing and removing the fixed components by scraping off the thermally conductive rubber sheet fixed after use or polishing the fixed surface.

  An object of the present invention is to provide a method for producing a heat conductive rubber sheet that is difficult to adhere to a heating element and a heat radiator and can be peeled relatively easily after use, and heat conductivity obtained by the production method. It is to provide a rubber sheet.

The present invention provides the following method for producing a heat conductive rubber sheet and a heat conductive rubber sheet.
[1] A primary crosslinking step of molding a thermally conductive resin composition containing a crosslinking component and a thermally conductive filler under heating to obtain a sheet-like molded product in which the crosslinking component is at least partially crosslinked. When,
A surface treatment step of contacting at least a part of the surface of the sheet-like molded product with a fluorine-based silane coupling agent;
The manufacturing method of the heat conductive rubber sheet containing this.

  [2] The method for producing a thermally conductive rubber sheet according to [1], further comprising a secondary crosslinking step of accelerating a crosslinking reaction of the crosslinking component in the sheet-like molded product by heat treatment.

  [3] The method for producing a thermally conductive rubber sheet according to [2], wherein the surface treatment step is performed between the primary crosslinking step and the secondary crosslinking step.

  [4] The method for producing a thermally conductive rubber sheet according to [2], wherein the surface treatment step is performed after the secondary crosslinking step.

  [5] The method for producing a heat conductive rubber sheet according to any one of [1] to [4], wherein the heat conductive rubber sheet is made of a fluorine-based rubber.

  [6] The crosslinkable component is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 hydrosilyl groups at the molecular ends, and the content of the molecule having 2 hydrosilyl groups is 60. ˜100 mol% of the fluorine-based compound (A1), and a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 alkenyl groups at the molecular ends, and having 2 alkenyl groups The manufacturing method of the heat conductive rubber sheet as described in [6] containing the fluorine-type compound (B1) whose molecular content rate is 60-100 mol%.

  [7] The fluorine-based compounds (A1) and (B1) are represented by the following formula [1]:

(In the formula, n is an integer of 1 to 10.)
The manufacturing method of the heat conductive rubber sheet as described in [6] which has the principal chain structure represented by these.

  [8] The method for producing a thermally conductive rubber sheet according to [6] or [7], wherein the alkenyl group of the fluorine compound (B1) is a vinyl group.

  [9] The heat according to any one of [1] to [8], wherein the thermally conductive resin composition includes 50 to 500 parts by weight of the thermally conductive filler with respect to 100 parts by weight of the crosslinkable component. A method for producing a conductive rubber sheet.

  [10] A thermally conductive rubber sheet obtained by the production method according to any one of [1] to [9].

  ADVANTAGE OF THE INVENTION According to this invention, the heat conductive rubber sheet which is hard to adhere to a heat generating body and a heat radiator and can be peeled comparatively easily after use can be provided. By applying the heat conductive sheet according to the present invention, it is possible to reduce additional labor and cost for cleaning and removing the fixed component, and particularly when applied to a semiconductor manufacturing apparatus, the additional labor and Costs can be reduced, and contaminants derived from fixed components that can greatly affect the yield and operational reliability of semiconductor devices can be reduced.

The method for producing the heat conductive rubber sheet of the present invention is as follows.
A primary crosslinking step in which a thermally conductive resin composition containing a crosslinking component and a thermally conductive filler (C) is molded under heating to obtain a sheet-like molded product in which the crosslinking component is at least partially crosslinked; And a surface treatment step in which at least a part of the surface of the sheet-like molded product is brought into contact with the fluorine-based silane coupling agent (E), and preferably promotes the crosslinking reaction of the crosslinkable component in the sheet-like molded product by heat treatment. And a secondary crosslinking step. Hereafter, each process is demonstrated in detail, showing embodiment.

[I] Primary cross-linking step (thermally conductive resin composition)
The heat conductive resin composition used as a raw material of the heat conductive rubber sheet contains a crosslinkable component that forms a rubber component as a binder component by a crosslink (curing) reaction, and a heat conductive filler (C).

  The crosslinkable component is not particularly limited as long as it can form a rubber component by a crosslinking (curing) reaction, and examples thereof include a silicon-containing crosslinkable component for forming silicone rubber and a fluorine-containing crosslinkable component for forming fluororubber. be able to. As the silicon-containing crosslinkable component, a silicon-containing crosslinkable component for forming a silicone rubber used in a conventionally known silicone rubber-based heat conductive sheet can be used.

  Among these, in the present invention, it is preferable to use a fluorine-containing crosslinkable component. A fluororubber-based thermally conductive rubber sheet using a fluorine-containing crosslinkable component is advantageous as compared with a silicone rubber-based thermally conductive rubber sheet in the following points, for example.

  a) Due to the nature of rubber, it is difficult to adhere to a heating element or a heat dissipation element even after use, as compared to a silicone rubber-based thermally conductive rubber sheet. The reason why silicone rubber-based heat conductive rubber sheets are relatively easy to fix is that when used in a high temperature environment, bleed components such as low molecular weight siloxane components are produced, and the rubber itself is susceptible to thermal degradation. is there. In comparison, fluororubber is less prone to generation of bleed components and thermal degradation.

b) Fluororubber is superior in heat resistance compared to silicone rubber.
c) For the reasons of a) and b), the generation amount of particles (fine particles) caused by decomposition of rubber due to bleed components or heat, which can be a contaminant that contaminates the manufacturing process of semiconductor devices, etc., is suppressed. Can do.

  d) For the reasons of a) to c) above, the fluororubber-based heat conductive rubber sheet requires a heat conductive sheet that can withstand use at a high temperature of 200 ° C. or higher, and the contamination of contaminants is severely restricted. The present invention can be suitably applied to a semiconductor manufacturing apparatus that has been used.

  From the above viewpoint, the heat conductive rubber sheet produced by the method of the present invention is preferably a heat conductive sheet composed of fluororubber, particularly when applied to a semiconductor manufacturing apparatus or the like. According to the present invention, it is possible to provide a heat conductive rubber sheet that is difficult to adhere to a heating element or a heat radiating element even when silicone rubber is used and can be peeled relatively easily after use.

In the case of using a fluorine-containing crosslinkable component, the crosslinkable component may be a fluorine-containing crosslinkable component that forms a conventionally known fluororubber, but at least the following fluorine-based compound:
Fluorine-based compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 hydrosilyl groups at the molecular ends, and having a molecule content of 2 hydrosilyl groups of 60 to 100 mol% (A1), and a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 alkenyl groups at the molecular ends, the content of the molecule having 2 alkenyl groups being 60 to 100 mol% Fluorine compound (B1)
It is preferable that it contains.

  According to the fluororubber-based heat conductive sheet comprising the heat-conductive resin composition containing the fluorine-based compounds (A1) and (B1), the advantages a) to d) described above can be obtained and the heat conduction It becomes possible to obtain a heat conductive sheet exhibiting hardness and surface adhesiveness suitable as a conductive sheet.

  The fluorine-based compounds (A1) and (B1) are a fluorine-based compound pair that forms a fluorine-based polymer (rubber-like elastic body) that exhibits elastomeric properties by a cross-linking (curing) reaction between them. “Elastomer characteristics” means that Shore A hardness measured in accordance with JIS K6253 is in the range of 20-40.

  The fluorine-based compound (A1) is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 hydrosilyl groups (SiH groups) at the molecular ends, and containing a molecule having 2 hydrosilyl groups The rate is 60 to 100 mol%, preferably 80 to 100 mol% (therefore, the content of molecules having one hydrosilyl group is 0 to 40 mol%, preferably 0 to 20 mol%), and fluorine-based It is a fluorine compound that can undergo an addition reaction with the alkenyl group of a fluorine compound having an alkenyl group at the molecular end, such as the compound (B1).

  The main chain structure of the fluorine-based compound (A1) can be composed of perfluorooxyalkylene units, and preferably the following formula [1]:

(In formula [1], n is an integer of 1 to 10)
It is a structure represented by.

  A typical example of a compound suitably used as the fluorine-based compound (A1) is the following formula [2]:

It is a hydrosilyl group terminal fluorine-type compound represented by these. In formula [2], n represents the same meaning as described above. Z ¹ is a cross-linking portion containing a hydrosilyl group and represents Si (H) (R ¹ ) ₂ . Z ² represents Si (H) (R ² ) ₂ similarly to Z ¹ in a molecule having ^two terminal hydrosilyl groups, and Si (R ³ ) ₃ in a molecule having one terminal hydrosilyl group. Represent.

R ¹ , R ² and R ³ may be the same or different and are each independently a substituted or unsubstituted monovalent hydrocarbon group. Specific examples thereof include a methyl group and an ethyl group. , N-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, alkyl group such as pentyl group, hexyl group; aryl group such as phenyl group, tolyl group, xylyl group A halogenated alkyl group such as a 3-chloropropyl group or a 3,3,3-trifluoropropyl group; R ¹ , R ² and R ³ are preferably alkyl groups having 1 to 5 carbon atoms.

  The fluorine compound (A1) preferably has a viscosity of 1.5 to 4.0 Pa · s measured according to JIS K7117-1.

  As the fluorine-based compound (A1) represented by the formula [2], trade name “SIFEL 8370-A” manufactured by Shin-Etsu Chemical Co., Ltd. can be preferably used.

  The fluorine-based compound (B1) is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 alkenyl groups at the molecular ends, and the content of molecules having 2 alkenyl groups is 60 to 100 mol%, preferably 80 to 100 mol% (therefore, the content of molecules having one alkenyl group is 0 to 40 mol%, preferably 0 to 20 mol%), and the fluorine-based compound (A1) Such a fluorine-based compound that can undergo an addition reaction with the hydrosilyl group of a fluorine-based compound having a hydrosilyl group at the molecular end.

  The main chain structure of the fluorine-based compound (B1) can be composed of perfluorooxyalkylene units, and is preferably a structure represented by the above formula [1]. Also in the fluorine compound (B1), n in the formula [1] is an integer of 1 to 10. The number of n in the fluorine compound (B1) may be the same as or different from that in the fluorine compound (A1).

  A typical example of the compound suitably used as the fluorine-based compound (B1) is the following formula [3]:

It is an alkenyl group terminal fluorine-type compound represented by these. In formula [3], n represents the same meaning as described above. Z ³ is a cross-linked portion containing an alkenyl group, and represents Si (alkenyl group) (R ⁴ ) ₂ . Z ⁴ represents Si (alkenyl group) (R ⁵ ) ₂ as in Z ³ in a molecule having two terminal alkenyl groups, and Si (R ⁶ ) _{3 in} a molecule having one terminal alkenyl group. Represents.

R ⁴ , R ⁵ and R ⁶ may be the same or different and are each independently a substituted or unsubstituted monovalent hydrocarbon group, and specific examples thereof include the above R ¹ , R ² and R ³ are the same as described above. R ⁴ , R ⁵ and R ⁶ are preferably alkyl groups having 1 to 5 carbon atoms.

  Examples of the alkenyl group include alkenyl groups having 2 to 8 carbon atoms such as vinyl group, methylvinyl group, allyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, and heptenyl group. Preferably it is an alkenyl group of about 2 to 4, more preferably a vinyl group.

  The fluorine-based compound (B1) preferably has a viscosity of 1.5 to 4.0 Pa · s measured according to JIS K7117-1.

  As the fluorine-based compound (B1) represented by the formula [3], a trade name “SIFEL 8370-B” manufactured by Shin-Etsu Chemical Co., Ltd. can be suitably used.

  The content ratio of the fluorine-based compound (A1) and the fluorine-based compound (B1) in the crosslinkable component can be within a range of, for example, 20/80 to 80/20, preferably 30/70. It is in the range of ˜70 / 30, more preferably in the range of 40/60 to 60/40 (for example, about 50/50).

  The crosslinkable component can include other crosslinkable components other than the fluorine-based compounds (A1) and (B1). For example, the crosslinkable component further includes the following two fluorine-based compounds (A2) and (B2): Can do. The fluorine-based compounds (A2) and (B2) are a fluorine-based compound pair that forms a fluorine-based polymer (gel-like elastic body) exhibiting gel characteristics by cross-linking (curing) between them. “Gel characteristics” means that the penetration measured in accordance with JIS K2207 is in the range of 60-80.

  In addition to the fluorine-based compounds (A1) and (B1), when the fluorine-based compounds (A2) and (B2) are further contained, even if the thermally conductive filler (C) is highly filled, a good low It is easy to obtain a heat conductive rubber sheet having both hardness and high surface adhesiveness and showing excellent heat transfer efficiency.

  That is, when a relatively large amount of the heat conductive filler (C) is contained in the heat conductive sheet itself in order to give high heat conductive performance, the hardness of the sheet is increased accordingly, and the adhesiveness of the sheet surface is increased. May decrease. Both the increase in hardness and the decrease in surface adhesiveness deteriorate the contact (adhesiveness) between the heating element and the heat dissipation element disposed adjacent to the heat conductive sheet, and increase the contact thermal resistance. It becomes a factor. When the contact thermal resistance is high, even if the thermal conductivity of the thermal conductive sheet itself is high, the performance cannot be fully exhibited, and a good thermal conduction efficiency from the heating element to the radiator is obtained. I can't.

  The combined use of the fluorine-based compounds (A1) and (B1) and the fluorine-based compounds (A2) and (B2) is an effective means for solving the above problems, and the thermally conductive filler (C) Even when high is filled, it is easy to obtain a heat conductive rubber sheet having both good low hardness and high surface tackiness.

  The fluorine-based compound (A2) is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 hydrosilyl groups (SiH groups) at the molecular ends, and containing a molecule having 2 hydrosilyl groups The rate is 0 to 40 mol%, preferably 20 to 40 mol% (therefore, the content of molecules having one hydrosilyl group is 60 to 100 mol%, preferably 60 to 80 mol%), and fluorine-based It is a fluorine-based compound that can undergo an addition reaction with the alkenyl group of the compounds (B1) and (B2).

  The main chain structure of the fluorine-based compound (A2) can be composed of perfluorooxyalkylene units, and is preferably a structure represented by the above formula [1]. Also in the fluorine compound (A2), n in the formula [1] is an integer of 1 to 10. The number of n in the fluorine compound (A2) may be the same as or different from that of the fluorine compound (A1) or (B1).

  A typical example of the compound suitably used as the fluorine-based compound (A2) is the following formula [4]:

It is a hydrosilyl group terminal fluorine-type compound represented by these. In formula [4], n represents the same meaning as described above. Z ⁵ and Z ⁶ represent the same meaning as Z ¹ and Z ² , respectively.

  The fluorine compound (A2) preferably has a viscosity of 1.5 to 500 Pa · s measured in accordance with JIS K7117-1.

  As the fluorine-based compound (A2) represented by the formula [4], trade names “SIFEL 3405-A”, “SIFEL 3505-A” and the like manufactured by Shin-Etsu Chemical Co., Ltd. can be suitably used.

  The fluorine-based compound (B2) is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 alkenyl groups at the molecular ends, and the content of molecules having 2 alkenyl groups is 0 to 0. 40 mol%, preferably 20 to 40 mol% (therefore, the content of the molecule having one alkenyl group is 60 to 100 mol%, preferably 60 to 80 mol%), and the fluorine-based compound (A1) And a fluorine-based compound capable of undergoing an addition reaction with the hydrosilyl group of (A2).

  The main chain structure of the fluorine-based compound (B2) can be composed of perfluorooxyalkylene units, and is preferably a structure represented by the above formula [1]. Also in the fluorine compound (B2), n in the formula [1] is an integer of 1 to 10. The number of n in the fluorine-based compound (B2) may be the same as or different from that of the fluorine-based compound (A1), (B1), or (A2).

  A typical example of a compound suitably used as the fluorine-based compound (B2) is the following formula [5]:

It is an alkenyl group terminal fluorine-type compound represented by these. In formula [5], n represents the same meaning as described above. Z ⁷ and Z ⁸ represent the same meaning as Z ³ and Z ⁴ , respectively. The alkenyl group is an alkenyl group having 2 to 8 carbon atoms such as a vinyl group, a methylvinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, and a heptenyl group, as in the fluorine compound (B1). Can be a group. Preferably it is an alkenyl group of about 2 to 4, more preferably a vinyl group. The alkenyl group of the fluorine compound (B2) may be the same as or different from the alkenyl group of the fluorine compound (B1).

  The fluorine compound (B2) preferably has a viscosity of 1.5 to 500 Pa · s measured according to JIS K7117-1.

  As the fluorine compound (B2) represented by the formula [5], trade names “SIFEL 3405-B”, “SIFEL 3505-B” and the like manufactured by Shin-Etsu Chemical Co., Ltd. can be suitably used.

In the case where the crosslinkable component contains the fluorine-based compounds (A1), (B1), (A2) and (B2), the heat conductive resin composition relates to the content of these fluorine-based compounds and is expressed by the following formula. [6] to [8]:
[(A1) + (B1)] / [(A2) + (B2)] = 20/80 to 80/20 [6]
(A1) / (B1) = 20/80 to 80/20 [7]
(A2) / (B2) = 20/80 to 80/20 [8]
It is preferable to satisfy.

  By containing the fluorine-based compounds (A1), (B1), (A2), and (B2) at a content ratio that satisfies the above formulas [6] to [8], the above-described effects are more effectively expressed. be able to.

  In order to obtain more excellent low hardness and high surface tackiness, the content ratio [(A1) + (B1)] / [(A2) + (B2)] is preferably 25/75 or more, It is more preferable to set it as 30/70 or more, and it is preferable to set it as 75/25 or less. The content ratio [(A1) + (B1)] / [(A2) + (B2)] can be, for example, about 70/30, 60/40, or about 50/50. When the content ratio [(A1) + (B1)] / [(A2) + (B2)] is less than 20/80, it tends to be difficult to mold into a heat conductive sheet. On the other hand, when the content ratio [(A1) + (B1)] / [(A2) + (B2)] exceeds 80/20, it is obtained by blending the fluorine-based compounds (A2) and (B2). It is difficult to recognize the above effect.

In addition to the above formula [6], the content ratios (A1) / (B1) and (A2) / (B2) are within the range of 20/80 to 80/20, respectively (the above formulas [7] and [8] In order to obtain more effective low hardness, it is possible to achieve the effect of achieving both good low hardness and high surface adhesion. (A1) / (B1) and (A2) / (B2) are represented by the following formulas [9] and [10]:
(A1) / (B1) = 20/80 to 40/60 or 60/40 to 80/20 [9]
(A2) / (B2) = 20/80 to 40/60 or 60/40 to 80/20 [10]
It is preferable to satisfy.

  That is, either one of the fluorine-based compounds (A1) or (B1) is excessively blended with respect to the other so as to satisfy the above formulas [9] and [10], and the fluorine-based compounds (A2) or (B2) By excessively blending any one of the above with respect to the other, an excessive amount of the fluorine-based compound acts effectively, and the low hardness of the thermally conductive sheet can be improved. However, when the excess is excessively large, that is, when the content ratio (A1) / (B1) or (A2) / (B2) is less than 20/80 or exceeds 80/20, the above formula [6 ], It tends to be difficult to mold into a heat conductive sheet.

  The excess fluorine-based compound has a molecular structure similar to that of the binder constituting the heat conductive sheet, and therefore does not bleed even when used at a high temperature (or extremely difficult to bleed). Bleeding of the sheet-containing component at the time of high-temperature use is a factor that pollutes the system, but the heat conductive sheet satisfying the above formulas [9] and [10] does not cause such a problem, and in this respect also has high heat resistance. It is sex.

As the heat conductive filler (C), it is preferable to use one having a thermal conductivity of 1 W / m · K or more. Specific examples include, for example, aluminum oxide (Al ₂ O ₃ ), crystalline silicon oxide (SiO ₂ ), magnesium oxide (MgO), beryllium oxide (BeO), zinc oxide (ZnO), silicon nitride (Si ₃ N ₄ ), boron nitride (hexagonal BN and cubic BN), aluminum nitride (AlN), silicon carbide (SiC), and diamond.

  The shape of the thermally conductive filler (C) can be granular, scale-like, needle-like, etc., but is preferably granular because it can be filled with higher density. The average particle diameter of the granular heat conductive filler (C) is, for example, 0.1 to 100 μm, and preferably 0.5 to 50 μm. The average particle size is d50 in the particle size distribution obtained by the laser diffraction / scattering method (microtrack method).

  As the heat conductive filler (C), one type of heat conductive filler may be used alone, or two or more types of heat conductive fillers may be mixed and used. In consideration of high density packing properties, two or more kinds of thermally conductive fillers having different average particle diameters can be mixed and used.

  Content of a heat conductive filler (C) is 50-500 weight part normally with respect to 100 weight part of said crosslinkable components, Preferably it is 100-400 weight part. When the content of the heat conductive filler (C) is 50 parts by weight or more, preferably 100 parts by weight or more, more preferably 250 parts by weight or more with respect to 100 parts by weight of the crosslinkable component, the heat conductive sheet itself is sufficient. Heat conductivity performance is easy to obtain. Moreover, the moldability to a heat conductive sheet can fully be ensured that content of a heat conductive filler (C) is 500 weight part or less with respect to 100 weight part of crosslinking | crosslinked components, Preferably it is 400 weight part or less. In addition, an increase in the hardness of the heat conductive sheet due to the extreme filling of the heat conductive filler can be suppressed.

  A heat conductive resin composition can contain the catalyst component (D) which catalyzes the crosslinking (curing) reaction of a crosslinkable component. For example, when the thermally conductive resin composition contains fluorine-based compounds (A1) and (B1), or when it further contains fluorine-based compounds (A2) and (B2), the thermally conductive resin composition has a hydrosilyl group and A platinum group catalyst that catalyzes a crosslinking reaction (hydrosilylation reaction) with an alkenyl group may be included. As the platinum group catalyst, a platinum catalyst is preferably used. Platinum-based catalysts include: platinum alone; chloroplatinic acid; platinum chloride; platinum-olefin complexes; platinum-alkenylsiloxane complexes; platinum-carbonyl complexes; platinum-phosphine complexes; platinum-alcohol complexes; In which platinum is supported on these carriers.

  Examples of platinum group catalysts other than platinum catalysts include rhodium compounds, ruthenium compounds, iridium compounds, and palladium compounds.

  The content of the catalyst component (D) such as a platinum group catalyst is not particularly limited as long as it is an effective amount necessary for accelerating the crosslinking and curing of the thermally conductive resin composition, and 100 parts by weight of the crosslinking component. Can be 0 to 10 parts by weight, and typically about 0.1 to 1000 ppm with respect to 100 parts by weight of the crosslinkable component.

  The heat conductive resin composition is optionally made of a plasticizer such as a fluorinated oil; a silane coupling agent; a surfactant; a crosslinking accelerator; a solvent; a dispersant; an anti-aging agent; an antioxidant; Pigments; additives such as conductive fillers such as carbon black, graphite (graphite), carbon nanotubes, carbon hollow particles, and carbon fibers can be included.

  By mixing the crosslinkable component described above, the heat conductive filler (C), the catalyst component (D) added as necessary, and other additives, and kneading and dispersing using a mixer, roll, etc. A heat conductive resin composition can be prepared.

(Primary crosslinking step)
This step is a step of obtaining a sheet-like molded product in which the crosslinkable component is at least partially crosslinked by molding the heat conductive resin composition as described above under heating. By this step, a sheet-like molded product having a crosslinking density that can be used as a heat conductive rubber sheet may be obtained. However, in the case where a secondary crosslinking step described later is provided, in this step, a partial crosslinkable component is used. Cross-linking (vulcanization). Since crosslinking (vulcanization) is easy to complete and the degassed component can be released more reliably, the crosslinking of the crosslinkable component is divided into a first crosslinking step (this step) and a second crosslinking step described later. It is preferable to carry out.

  The temperature (crosslinking temperature) at the time of molding into a sheet-like molded product in this step can be, for example, 90 to 150 ° C. The molding method is not particularly limited, and press molding (compression molding), injection molding, transfer molding, extrusion molding, cast molding, blow molding, calendar molding, and the like can be used.

[II] Secondary Crosslinking Step As described above, the method for producing a heat conductive rubber sheet of the present invention heats the crosslinking (curing) reaction of the crosslinkable component in the sheet-like molded product formed by the primary crosslinking step. A secondary cross-linking step promoted by treatment can be included. The crosslinking conditions in this step are preferably adjusted as appropriate so that desired rubber hardness, rubber elastic modulus, and the like can be obtained. The temperature of the heat treatment in this step can be set to 120 to 180 ° C., for example.

[III] Surface treatment step This step is a step of bringing at least a part of the surface of the sheet-like molded product into contact with the fluorinated silane coupling agent (E). According to the method for producing a heat conductive rubber sheet of the present invention including this step, a heat conductive rubber sheet that is prevented from adhering to a heat generator or a heat radiator and can be peeled relatively easily even after use. Can be obtained.

  That is, it exists on the surface of a heat generating body or a heat radiator as a main factor which a heat generating body and a heat radiator (these are often made of a metal such as aluminum) and a heat conductive rubber sheet adhere. It is mentioned that a functional group such as —COOH group or —OH group and a functional group present on the surface of the heat conductive rubber sheet may form a chemical bond during use. By surface treatment that brings the surface into contact with the fluorinated silane coupling agent (E), the functional group on the surface of the sheet-like molded product is fluorinated (increases the fluorine content on the surface) and is present on the surface of the heating element and heat radiator. The amount of the functional group that can react with the functional group to be reduced can be effectively reduced. Thereby, the said chemical bond which is the main factor which generate | occur | produces sticking force can be suppressed effectively.

  For example, in the case of using a thermally conductive resin composition containing the above-described fluorine-based compound as a crosslinkable component, -H, -OH group, -SiH group, alkenyl group (carbon- There may be a functional group such as a carbon double bond, and the functional group forms a chemical bond with the functional group present on the surface of the heating element or the heat radiating member, for example, by causing a dehydration reaction during use. In addition, when silicone rubber is used, a functional group such as a -SiH group may be present on the surface of the sheet-like molded product, and the functional group may be a functional group present on the surface of a heating element or a heat dissipation element. During use, for example, a dehydration reaction is caused to form a chemical bond, and due to the relatively low heat resistance of silicone rubber, the rubber gradually decomposes and deteriorates in a state where such a chemical bond is formed. Therefore, firm fixation occurs as compared with the case of using fluororubber.

  The surface of the sheet-like molded article subjected to the surface treatment to be brought into contact with the fluorine-based silane coupling agent (E) is at least a part of the surface of the sheet-like molded article, but preferably two main surfaces of the sheet-like molded article Is more preferably the entire surface of the two main surfaces of the sheet-like molded product. Furthermore, you may surface-treat the side surface of a sheet-like molding.

  When only the primary crosslinking step is performed and the secondary crosslinking step is not performed, the surface treatment step is performed after the primary crosslinking step. On the other hand, when the secondary crosslinking step is performed after the primary crosslinking step, the surface treatment step may be performed between the primary crosslinking step and the secondary crosslinking step, or may be performed after the secondary crosslinking step. Good. The above-described effects can be obtained regardless of the timing of the surface treatment process. However, from the viewpoint of production efficiency, it is preferable to perform a surface treatment step between the primary crosslinking step and the secondary crosslinking step.

  The specific means for bringing the surface of the sheet-like molded product into contact with the fluorine-based silane coupling agent (E) is not particularly limited, and the surface of the sheet-like molded product can be formed on the surface by a known method such as coater, roll, spray, dip (immersion). A method of applying the ring agent (E) can be used.

  In order to promote the reaction between the functional group present on the surface of the sheet-like molded product and the fluorine-based silane coupling agent (E), after applying the fluorine-based silane coupling agent (E), the sheet-shaped molded product is Can be heated. The heating temperature is not particularly limited, but can be, for example, about 40 to 150 ° C, and preferably 80 to 130 ° C. When performing a surface treatment process between a primary crosslinking process and a secondary crosslinking process, since the heat processing in a secondary crosslinking process accelerates | stimulates reaction with a fluorine-type silane coupling agent (E), it also serves as the said heat processing. It may be.

The fluorine-based silane coupling agent (E) has an organic functional group and a hydrolyzable silyl group in the molecule, and contains a fluorine atom in the organic functional group. As the fluorine-based silane coupling agent (E) preferably used, the following formula [11]:
R _f (CH ₂ ) _m —SiR _a X _3-a [11]
The fluorine-type silane coupling agent represented by these can be mentioned.

In the formula [11], R _f is a perfluoroalkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, R is a methyl group or an ethyl group, and X is a hydrolyzable group (Cl, Br M is an integer of 0 to 5 (preferably an integer of 1 to 3), and a is 0 or 1.

Specific examples of the fluorine-based silane coupling agent represented by the formula [11] include, for example, CF ₃ (CH ₂ ) ₂ SiCl ₃ ; CF ₃ (CF ₂ ) ₅ SiCl ₃ ; CF ₃ (CF ₂ ) ₅ (CH _{2 2} SiCl ₃ ; CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ SiCl ₃ ; CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ; CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (CH ₃ ) Cl ₂ ; CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ; CF ₃ (CH ₂ ) ₂ Si (CH ₃ ) (OCH ₃ ) ₂ ; CF ₃ (CF ₂ ) ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ; CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ; CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (CH ₃ ) (OCH ₃ ) ₂ ; CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ . Among them, CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ (trifluoropropyltrimethoxysilane) is one of fluorine-based silane coupling agents that are preferably used. A fluorine-type silane coupling agent (E) may be used individually by 1 type, and may use 2 or more types together.

  In the above-mentioned specific means for bringing the surface of the sheet-like molded product into contact with the fluorine-based silane coupling agent (E), the fluorine-based silane coupling agent (E) may be used as it is without being diluted, or the fluorine-based silane. A liquid (for example, a solution) obtained by diluting the coupling agent (E) can also be used. As the solvent for diluting the fluorine-based silane coupling agent (E), for example, water or various organic solvents can be used. The concentration of the fluorine-based silane coupling agent (E) in the liquid is preferably 10% by weight to less than 100% by weight, and more preferably 15% by weight or more. When the concentration is less than 10% by weight, it is difficult to obtain a desired effect by the surface treatment using the fluorine-based silane coupling agent (E).

  Although the thickness of the heat conductive rubber sheet manufactured through the above steps is appropriately set depending on the application to be applied, it is usually about 0.05 to 3 mm, preferably about 0.1 to 1 mm. is there.

  In addition, in order to further reduce the adhesive force of the heat conductive rubber sheet, a fluorine-based silane coupling agent is applied to the surface of the heating element and the heat radiating body in contact with the heat conductive rubber sheet as well as the surface treatment of the sheet-like molded product. It is also preferable to perform the same surface treatment using (E).

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples. The test method of the evaluation test performed about the heat conductive sheet obtained by the following Example and comparative example is as follows. The evaluation test results are shown in Table 1.

[A] Thermal resistance A sample piece having a length of 10 mm, a width of 10 mm, and a thickness of 1.0 mm cut out from a heat conductive rubber sheet was attached to a heat generating substrate (amount of heat generation: 45 W). A substrate with a cooling mechanism made of the same material as that of the heat generating substrate was placed on the sample piece and pressed with a constant load of 98 kPa. Temperature sensors were attached to both substrates, and the heating substrate was energized while monitoring the temperature of both substrates. Measure the temperature T ₁ (° C.) of the heat generating substrate and the substrate T ₂ (° C.) with a cooling mechanism after 5 minutes from the start of energization.
Thermal resistance (° C./W)=(T ₁ −T ₂ ) / Q [Q is the amount of heat generated by the heating substrate (W)]
Based on the above, the thermal resistance was calculated.

[B] Hardness The hardness of the thermally conductive sheet at 25 ° C. was measured using an ASKER C hardness meter manufactured by ASKER.

[C] Tensile strength and tensile elongation From the force (maximum load) required to pull and break a dumbbell-shaped (No. 2 type) test piece made from a heat conductive sheet at a constant speed according to JIS K6251 The tensile strength (MPa) was determined as the tensile elongation (%) from the elongation at break (measurement temperature 23 ° C.).

[D] Peel strength (stickiness)
A laminate of a 15 mm square (0.5 mm thick) test piece cut out from a thermally conductive sheet and a metal plate (30 mm thick) made of alumite sulfate is placed between two anodized flanges and compressed. The flange was tightened with bolts / nuts while adjusting with a shim so that the rate was 20%, and then heat treatment was performed at 200 ° C. for 65 hours in a vacuum atmosphere. Next, the flange pair after the heat treatment is sufficiently cooled in a thermostat (temperature 23 ° C., relative humidity 50%), and after confirming that the flange temperature is 23 ° C., tensile compression made by Minebea Co., Ltd. Using a universal material testing machine, the peel strength (sticking force, N) at the time of peeling the flange (that is, when peeling the test piece and the metal plate) was measured.

<Example 1>
Each compounding component shown in the table with the compounding ratio shown in Table 1 (the unit of numerical values is parts by weight) was mixed using an automatic mortar, and further passed through a roll to be highly dispersed. The obtained kneaded material was molded into a sheet shape by a hot press (100 ° C., 10 minutes) using a mold to obtain a sheet-shaped molded product (primary crosslinking step). Next, the obtained sheet-like molded product was immersed in a fluorine-based silane coupling agent-containing liquid at 25 ° C. for 5 minutes (surface treatment step). A solution (solvent: ion-exchanged water) containing 50% by weight of “KBM-7103” (trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. was used as the fluorine-based silane coupling agent-containing liquid.

  Next, the sheet-like molded product treated with the fluorine-based silane coupling agent is subjected to a heat treatment at 100 ° C. for 1 hour using an electric furnace (secondary crosslinking step) to produce a heat conductive rubber sheet. did.

<Example 2>
A thermally conductive rubber sheet was produced in the same manner as in Example 1 except that the heat treatment conditions in the secondary crosslinking step were 120 ° C. and 1 hour.

<Example 3>
After carrying out the primary crosslinking step in the same manner as in Example 1, the secondary crosslinking step was carried out in the same manner as in Example 1 without carrying out the surface treatment step. Then, after immersing in the fluorine-type silane coupling agent containing liquid like Example 1, 100 degreeC and the heat processing for 1 hour were performed again, and the heat conductive rubber sheet was produced.

<Comparative Example 1>
A thermally conductive rubber sheet was produced in the same manner as in Example 1 except that the step of immersing in the fluorinated silane coupling agent-containing liquid was not performed.

<Comparative Example 2>
Other than not using the blending ratio shown in Table 1 (the unit of the numerical value is parts by weight) and using each blending component shown in the same table and immersing in the fluorinated silane coupling agent-containing liquid In the same manner as in Example 1, a silicone rubber-based thermally conductive rubber sheet was produced.

The detail of each compounding component used by the Example and the comparative example is as follows.
[A] Fluorine compound (A1): trade name “SIFEL 8370-A” manufactured by Shin-Etsu Chemical Co., Ltd. (fluorine compound in which the content of molecules having two hydrosilyl groups is in the range of 60 to 100 mol%) Compound),
[B] Fluorine compound (B1): trade name “SIFEL 8370-B” manufactured by Shin-Etsu Chemical Co., Ltd. (fluorine compound in which the content of molecules having two alkenyl groups is in the range of 60 to 100 mol%) Compound),
[C] Silicon compound: “Sircon” manufactured by Fuji Polymer Co., Ltd.
[D] Aluminum oxide A: “DAM-45” (average particle diameter: 40 μm) manufactured by Denki Kagaku Kogyo Co., Ltd.
[E] Aluminum oxide B: “DAM-05A” (average particle size 0.5 μm) manufactured by Denki Kagaku Kogyo Co., Ltd.
[F] Platinum catalyst: “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd. (platinum supported amount: 50% by weight).

  In Comparative Examples 1 and 2, the test piece made of the heat conductive sheet was broken in the evaluation test for obtaining the peel strength, and the peel strength could not be measured. The numerical values shown in Table 1 are values that are temporarily measured in the evaluation test for obtaining the peel strength, and these numerical values correspond to the breaking stress. The peel strength is greater than the breaking stress.

Claims (10)

A primary crosslinking step of molding a thermally conductive resin composition containing a crosslinking component and a thermally conductive filler under heating to obtain a sheet-like molded product in which the crosslinking component is at least partially crosslinked;
A surface treatment step of contacting at least a part of the surface of the sheet-like molded product with a fluorine-based silane coupling agent;
The manufacturing method of the heat conductive rubber sheet containing this.   The manufacturing method of the heat conductive rubber sheet of Claim 1 which further includes the secondary crosslinking process which accelerates | stimulates the crosslinking reaction of the said crosslinkable component in the said sheet-like molding by heat processing.   The manufacturing method of the heat conductive rubber sheet of Claim 2 which performs the said surface treatment process between the said primary crosslinking process and the said secondary crosslinking process.   The manufacturing method of the heat conductive rubber sheet of Claim 2 which performs the said surface treatment process after the said secondary bridge | crosslinking process.   The said heat conductive rubber sheet is a manufacturing method of the heat conductive rubber sheet of any one of Claims 1-4 comprised with a fluoro rubber.   The crosslinkable component is a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 hydrosilyl groups at the molecular ends, and the content of the molecule having 2 hydrosilyl groups is 60 to 100 mol. % Fluorine-based compound (A1), and a compound having a perfluoroalkyl ether structure in the main chain and having 1 to 2 alkenyl groups at the molecular ends, and having 2 molecules of alkenyl groups The manufacturing method of the heat conductive rubber sheet of Claim 5 containing the fluorine-type compound (B1) whose rate is 60-100 mol%. The fluorine-based compounds (A1) and (B1) are represented by the following formula [1]:

(In the formula, n is an integer of 1 to 10.)
The manufacturing method of the heat conductive rubber sheet of Claim 6 which has the principal chain structure represented by these.   The manufacturing method of the heat conductive rubber sheet of Claim 6 or 7 whose alkenyl group which the said fluorine-type compound (B1) has is a vinyl group.   The thermally conductive rubber according to claim 1, wherein the thermally conductive resin composition contains 50 to 500 parts by weight of the thermally conductive filler with respect to 100 parts by weight of the crosslinkable component. Sheet manufacturing method.   The heat conductive rubber sheet obtained by the manufacturing method of any one of Claims 1-9.