JP2018094812A - Pressurizing method and method of manufacturing composite material sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of pressurizing particles of a composite material capable of manufacturing a composite material sheet which can efficiently produce a composite material sheet even when a composite material sheet is manufactured using, for example, a laminate of a primary composite material sheet, and capable of forming a thickened primary composite material sheet.SOLUTION: A pressurizing method in which particles of a composite material containing a resin and an inorganic material are primarily pressed in a state of being sandwiched between two sheet base materials, where a blocking resistance of particles of the composite material is 0% or more and 80% or less, and a peeling force of at least one sheet base material out of the two sheet base materials is 0.03 N/cm or more and less than 4.0 N/cm.SELECTED DRAWING: None

Description

  The present invention relates to a pressing method and a method for producing a composite material sheet. More specifically, the present invention relates to a method for pressurizing particles of a composite material and a method for manufacturing a composite material sheet.

  In recent years, a sheet-like member (composite material sheet) using a composite material including a resin and an inorganic material having characteristics such as thermal conductivity has been used for various applications.

  Here, the composite material sheet is prepared by, for example, preparing a primary sheet once in order to impart anisotropy of desired physical properties such as thermal conductivity and conductivity, and slicing a laminate formed by laminating the primary sheet. It may be manufactured by doing.

  For example, in Patent Document 1, a pre-heat conductive sheet having a thickness of 0.3 mm is obtained by pressure-molding particles obtained by pulverizing a composition containing an acrylic resin and a carbon material when manufacturing a heat conductive sheet. (Primary sheet) is used. And in patent document 1, 200 sheets of the said pre heat conductive sheet are laminated | stacked on the thickness direction, and the carbon material is orientated to a desired direction by slicing the laminated body of the obtained pre heat conductive sheet to a lamination direction. Yes.

International Publication No. 2016/129257

  However, in the conventional method described in Patent Document 1 or the like, it is necessary to stack a large number of primary sheets, and there is a problem that the working efficiency when manufacturing a composite material sheet such as a heat conductive sheet is inferior.

  With regard to the above problems, the inventors of the present invention can improve the manufacturing efficiency of the composite material sheet even when the laminate is used, by increasing the thickness of the primary sheet itself and reducing the number of primary sheets stacked. Focused on getting. However, when preparing a primary sheet by pressure-molding particles comprising a composition containing a resin and an inorganic material, increasing the thickness of the primary sheet may give sufficient pressure to the particles during pressure molding. It was not possible to make the particles into a good sheet.

Therefore, the present invention can form a thickened primary composite sheet, for example, efficiently manufacturing a composite sheet even when a composite sheet is manufactured using a laminate of primary composite sheets. Another object of the present invention is to provide a method for pressing particles of a composite material.
Moreover, an object of this invention is to provide the manufacturing method of a composite material sheet | seat which can manufacture a composite material sheet | seat efficiently.

The present inventors have intensively studied to achieve the above object. Then, the present inventors put the composite material particles containing the resin and the inorganic material between the sheet base materials and pressurize them to form the primary composite material sheet. We focused on the peelability of the material. The inventors of the present invention have that the composite material particles have a certain degree of stickiness, the anti-blocking rate (powder fluidity) is suppressed within a predetermined range, and at least one of the sheet base materials. It has been found that if the peel force is within a predetermined range, a thickened primary composite sheet can be obtained satisfactorily. Then, the inventors have found that a composite material sheet can be efficiently produced by laminating and slicing the primary composite material sheet, thus completing the present invention.
In the present invention, “blocking” means that particles of the composite material are adhered to each other due to the stickiness caused by the resin in the particles of the composite material to form a lump.

That is, the present invention aims to advantageously solve the above-mentioned problems, and the pressurizing method of the present invention allows particles of a composite material containing a resin and an inorganic material to be placed between two sheet substrates. A pressurizing method for primary pressurization in a sandwiched state, wherein the composite material particles have a blocking resistance of 0% or more and 80% or less, and at least one of the two sheet base materials. The peeling force is 0.03 N / cm or more and less than 4.0 N / cm. As described above, when the composite material particles containing the resin and the inorganic material are sandwiched between the sheet base material and pressure-molded, the blocking resistance of the composite material particles is suppressed within the predetermined range, and the sheet base material If at least one peeling force is within the predetermined range, a thickened primary composite sheet can be obtained satisfactorily.
In the present invention, “blocking resistance” and “peeling force” can be measured by the methods described in the examples of the present specification.

  In the pressurizing method of the present invention, it is preferable that the peeling force of at least one of the two sheet base materials is 0.30 N / cm or more and 3.00 N / cm or less. This is because if the peel force of at least one of the sheet base materials is within the above range, the primary composite material sheet can be further thickened.

  And it is preferable that the thickness of the primary composite material sheet obtained by the said primary pressurization is 1.0 mm or more as for the pressurization method of this invention. This is because, if the thickness of the primary composite material sheet is increased in this way, for example, the composite material sheet can be efficiently manufactured using the primary composite material sheet.

  Moreover, this invention aims at solving the said subject advantageously, The manufacturing method of the composite material sheet | seat of this invention is the process of obtaining a primary composite material sheet according to one of the pressurization methods mentioned above. A step of laminating a plurality of the primary composite sheets in the thickness direction, or folding or winding the primary composite sheet to obtain a laminate, and the laminate is 45 ° or less with respect to the lamination direction. And obtaining a composite material sheet by slicing at an angle of. In this way, since the primary composite material sheet having a thick film can be obtained according to any of the above-described pressing methods, the composite material sheet can be efficiently produced using the primary composite material sheet. . In addition, if the laminate of the primary composite sheet is sliced in the stacking direction, the inorganic material is oriented in a desired direction such as the thickness direction in the composite sheet, and the composite sheet exhibits desired characteristics such as thermal conductivity. Can be made.

  The method for producing a composite material sheet of the present invention further includes a step of obtaining a compressed laminate by compressing the laminate by second pressurization in the laminating direction, and in the step of obtaining the composite material sheet, the compression It is preferable to obtain a composite material sheet by slicing the laminate at an angle of 45 ° or less with respect to the lamination direction. By using a compression laminate obtained by subjecting the laminate to secondary pressure in the laminating direction, the composite material sheet is oriented in a desired direction, such as the thickness direction, in the composite material sheet, and the composite material sheet has a desired thermal conductivity or the like. This is because the characteristics can be exhibited more.

Moreover, it is preferable that the manufacturing method of the composite material sheet of this invention is 1% or more and 30% or less of the decreasing rate of the laminated body height by the said secondary pressurization. If the reduction rate of the laminate height due to secondary pressurization is within the above range, the composite material sheet is oriented more favorably in a desired direction such as the thickness direction, and the composite material sheet is thermally conductive in the thickness direction. This is because desired characteristics such as can be further exhibited.
In the present invention, the “reduction rate of the laminate height” is expressed by the following formula (1):
Decrease rate of laminate height (%) =
(Height of laminated body before secondary pressurization (mm)-Height of compressed laminate after secondary pressurization (mm))
/ Height of laminated body before secondary pressurization (mm) × 100 (1)
Can be calculated according to Here, the height of the laminate and the compressed laminate can be measured by the method described in the examples of the present specification.

  Moreover, it is preferable that the manufacturing method of the composite material sheet of the present invention further includes a step of compressing the composite material sheet obtained according to any one of the manufacturing methods described above by tertiary pressure in the thickness direction. If the composite material sheet is subjected to tertiary pressure in the thickness direction, the surface smoothness of the composite material sheet can be improved. Therefore, for example, when the composite material sheet is used in contact with an adherend such as a heating element and a heat radiating member, the adhesion between the composite material sheet and the adherend is improved, and the composite material sheet has a desired thermal conductivity or the like. This is because the above characteristics can be exhibited better.

And the manufacturing method of the composite material sheet | seat of this invention WHEREIN: It is preferable that the decreasing rate of the sheet thickness by the said tertiary pressurization is 1% or more and 40% or less. If the composite material sheet is subjected to the third pressurization so that the reduction rate of the sheet thickness is within the predetermined range, the surface smoothness of the composite material sheet can be improved while ensuring good orientation of the inorganic material in the composite material sheet. This is because the composite sheet can be further enhanced to exhibit desired characteristics such as thermal conductivity more satisfactorily.
In the present invention, the “sheet thickness reduction rate” is expressed by the following formula (2):
Reduction rate of sheet thickness (%) =
(Thickness of composite material sheet before tertiary pressurization (mm) −Thickness of composite material sheet after tertiary pressurization (mm)) / Thickness of composite material sheet before tertiary pressurization (mm) × 100 (2) )
Can be calculated according to Here, the thickness of the composite material sheet before and after the third pressurization can be measured by the method described in the examples of the present specification.

According to the present invention, a thickened primary composite material sheet can be formed. For example, even when a composite material sheet is manufactured using a laminate of primary composite material sheets, the composite material sheet is efficiently manufactured. It is possible to provide a method for pressing the particles of the composite material.
Moreover, according to this invention, the manufacturing method of a composite material sheet which can manufacture a composite material sheet efficiently can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
The pressurizing method of the present invention can be used to obtain a primary composite material sheet that can be used for producing a composite material sheet having desired characteristics such as thermal conductivity. Moreover, the manufacturing method of the composite material sheet of this invention can be used in order to obtain a composite material sheet efficiently using the primary composite material sheet obtained according to the said pressurization method.
Then, according to the pressurizing method of the present invention, at the time of press molding in a state where the composite material particles having a blocking resistance suppressed within a predetermined range are sandwiched between the sheet base materials, at least one of the sheet base materials Since a sheet base material having a peeling force within a predetermined range is used, it is possible to increase the thickness of the obtained primary composite material sheet. Moreover, according to the method for producing a composite material sheet of the present invention, since the primary composite material sheet is used, the composite material sheet can be produced efficiently.

  In addition, the composite material sheet obtained according to the method for manufacturing a composite material sheet of the present invention is, for example, sandwiched between the heat generator and the heat radiator when the heat radiator is attached to the heat generator, and allows good heat dissipation from the heat generator. It can be suitably used as a heat conductive sheet. And when using the composite material sheet obtained according to the production method of the present invention as a heat conductive sheet, the heat conductivity in the thickness direction of the composite material sheet is, for example, 0.1 MPa or less, preferably 0.06 MPa or less. When sandwiched and used at a relatively low pressure, it can be improved more effectively.

(Pressurization method)
The pressurizing method of the present invention is a method for primary pressurizing a composite material particle containing a resin and an inorganic material and having a blocking resistance suppressed within a predetermined range while being sandwiched between two sheet base materials. At least one of the sheet base materials is a sheet base material having a peeling force within a predetermined range. When the composite material particles are sandwiched between the sheet base materials and subjected to pressure molding, the anti-blocking rate of the composite material particles is within the predetermined range, and the peeling force of at least one of the sheet base materials is not within the predetermined range. The primary composite material sheet to be described later cannot be formed favorably by increasing the film thickness.
In addition, the pressurization method of the present invention may further include other steps such as a step of obtaining composite material particles, for example, prior to the primary pressurization.

<Step of obtaining composite material particles>
In the step of obtaining particles of the composite material that can be optionally included in the pressurizing method of the present invention, for example, a composite mixture prepared by mixing and kneading a resin, an inorganic material, and an optional additive is used as it is. It may be obtained as particles. Further, when the composite mixture has a non-particle shape such as a lump, in the step of obtaining particles of the composite material, for example, the composite mixture is further pulverized and pulverized by an arbitrary method to obtain a particle shape. May be obtained as composite material particles. Among these, from the viewpoint of improving the handleability of the composite material particles, in the step of obtaining the composite material particles, it is preferable to crush and pulverize the composite mixture to obtain composite material particles.
In the pressurizing method of the present invention, for example, the composite material particles obtained as described above can be primarily pressurized.

<< Composite Material Particles >>
The particles of the composite material contain a resin and an inorganic material and have a blocking resistance suppressed within a predetermined range. Further, the composite material particles may optionally further contain an additive in addition to the resin and the inorganic material. As the composite material particles, for example, composite material particles obtained according to the above-described step of obtaining composite material particles may be used, or commercially available products may be used.

[resin]
The resin is not particularly limited, and for example, a thermoplastic resin or a thermosetting resin can be used.

[[Thermoplastic resin]]
Among them, it is preferable to use a thermoplastic resin as the resin. This is because, if a thermoplastic resin is used as the resin, for example, particles of a composite material in which the components are uniformly mixed can be easily obtained by mixing the resin and the inorganic material while heating. Further, for example, the resulting composite material particles are excellent in moldability, such as being able to improve the smoothness of the sheet surface by forming a sheet by applying pressure (heating press) while heating.
Examples of the thermoplastic resin include a thermoplastic resin that is liquid at normal temperature and pressure, and a solid thermoplastic resin that is solid at normal temperature and pressure.

-Liquid thermoplastic resin at room temperature and normal pressure-
Among these, as the resin, it is preferable to use a liquid thermoplastic resin at least under normal temperature and normal pressure, and it is more preferable to use only a liquid thermoplastic resin under normal temperature and normal pressure. This is because if a thermoplastic resin that is liquid at least at room temperature and normal pressure is used as the resin, the composite particles are imparted with appropriate stickiness and the blocking resistance can be more easily suppressed. For example, the use of the composite material particles makes it easier to form a thicker primary composite sheet. Further, if a thermoplastic resin that is liquid at least at room temperature and normal pressure is used as the resin, it is easy to obtain more uniform composite material particles.
In this specification, “normal temperature” refers to 23 ° C., and “normal pressure” refers to 1 atm (absolute pressure).

  Examples of the thermoplastic resin that is liquid under normal temperature and normal pressure include fluorine resin, silicone resin, acrylic resin, and epoxy resin. These may be used individually by 1 type and may use 2 or more types together. Among these, as the thermoplastic resin that is liquid at normal temperature and pressure, it is preferable to use a thermoplastic fluororesin that is liquid at normal temperature and pressure. If a thermoplastic fluororesin that is liquid at room temperature and normal pressure is used, in addition to the above effects, heat resistance, oil resistance, and chemical resistance of composite material particles and composite material sheets obtained using composite material particles, etc. It is because it can improve.

  The viscosity of the thermoplastic resin that is liquid at room temperature and normal pressure is not particularly limited, but the viscosity at a temperature of 105 ° C. is 500 mPaS in terms of good kneadability, fluidity, crosslinking reactivity, and excellent moldability. -It is preferable that it is s-30000 mPa * s, and it is more preferable that it is 550 mPa * s-25000 mPa * s.

-Solid thermoplastic resin at room temperature and normal pressure-
Examples of the thermoplastic resin that is solid under normal temperature and normal pressure include poly (2-ethylhexyl acrylate), a copolymer of acrylic acid and 2-ethylhexyl acrylate, polymethacrylic acid or an ester thereof, polyacrylic acid or Acrylic resins such as esters; silicone resins; fluororesins; polyethylenes; polypropylenes; ethylene-propylene copolymers; polymethylpentenes; polyvinyl chlorides; polyvinylidene chlorides; polyvinyl acetates; Polyacetal, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene copolymer (nitrile rubber) Acrylonitrile-butadiene-styrene copolymer (ABS resin); styrene-butadiene block copolymer or hydrogenated product thereof; styrene-isoprene block copolymer or hydrogenated product thereof; polyphenylene ether; modified polyphenylene ether; aliphatic polyamide Aromatic polyamides; Polyamideimide; Polycarbonate; Polyphenylene sulfide; Polysulfone; Polyethersulfone; Polyether nitrile; Polyetherketone; Polyketone; Polyurethane; Liquid crystal polymer; These may be used individually by 1 type and may use 2 or more types together.
In the present invention, rubber is included in “resin”.

-Thermosetting resin-
Furthermore, a thermosetting resin may be used as the resin as long as the effects of the present invention are not significantly impaired. Examples of the thermosetting resin include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, and polyisobutylene. Rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, polyimide silicone resin, polyurethane, thermosetting polyphenylene ether, thermosetting modified polyphenylene ether, etc. It is done. These may be used individually by 1 type and may use 2 or more types together.

[[Resin content]]
The content ratio of the resin in the particles of the composite material is not particularly limited and is preferably 35% by mass or more, more preferably 55% by mass or more, and 95% by mass or less. preferable. This is because if the resin content is at least the above lower limit, moderate stickiness is imparted by the particles of the composite material, and the blocking resistance can be more easily suppressed. For example, by using particles of the composite material, it is easy to form a primary composite material sheet that is excellent in flexibility and further thickened. Moreover, if the resin content is equal to or lower than the above upper limit, for example, a composite material sheet obtained using the composite material particles can easily exhibit desired characteristics.

[Inorganic materials]
The inorganic material is not particularly limited. For example, the inorganic material can be any inorganic material that can exhibit desired characteristics to be imparted to the composite material sheet obtained using the composite material particles. Examples of such inorganic materials include carbon materials, boron nitride, aluminum nitride, titanium oxide, and the like. Furthermore, examples of the carbon material include a particulate carbon material and a fibrous carbon material.
For example, when high thermal conductivity is imparted to the composite material sheet, among the above, the inorganic material is preferably a particulate carbon material, a fibrous carbon material, boron nitride, and aluminum nitride, and at least particles More preferably, it includes a particulate carbon material, and further preferably includes a particulate carbon material and a fibrous carbon material. For example, when giving high light reflectivity to a composite material sheet, it is preferable that an inorganic material is a titanium oxide among the above-mentioned.

In addition, the inorganic material mentioned above may be used individually by 1 type, and may use 2 or more types together. In the present invention, when the inorganic material has a particle shape, it may be referred to as “inorganic particles”.
Hereinafter, an example in which a composite material sheet using composite material particles obtained according to the pressurizing method of the present invention is used as a heat conductive sheet may be described, but the present invention is not limited to this example.

[[Particulate carbon material]]
The particulate carbon material that can be used as the inorganic particles is not particularly limited. For example, graphite such as artificial graphite, flake graphite, exfoliated graphite, natural graphite, acid-treated graphite, expandable graphite, and expanded graphite; Carbon black; etc. can be used. These may be used individually by 1 type and may use 2 or more types together.
Among them, it is preferable to use expanded graphite as the particulate carbon material. This is because if expanded graphite is used, the thermal conductivity of the composite material sheet can be further improved.

-Expanded graphite-
Here, the expanded graphite that can be suitably used as the particulate carbon material is, for example, finely expanded after heat-treating expandable graphite obtained by chemically treating graphite such as scaly graphite with sulfuric acid or the like. Can be obtained. Examples of commercially available expanded graphite include EC-1500, EC-1000, EC-500, EC-300, EC-100, EC-50 (all trade names) manufactured by Ito Graphite Industries Co., Ltd. Can be mentioned.

[[Particle size of inorganic particles]]
Here, the particle diameter of the inorganic particles such as the particulate carbon material is preferably 100 μm or more in terms of volume average particle diameter, more preferably 150 μm or more, preferably 300 μm or less, and 250 μm or less. It is more preferable. This is because, if the particle diameter of the inorganic particles is equal to or greater than the above lower limit, for example, desired characteristics and strength such as good thermal conductivity can be given by the composite material sheet using the composite material particles. Moreover, if the particle diameter of the inorganic particles is less than or equal to the above upper limit, for example, the mixing ease when mixing the resin and the inorganic particles and the moldability when forming the particles of the composite material are excellent.
In the present specification, the “volume average particle diameter” represents a particle diameter (D50) at which the cumulative volume calculated from the small diameter side is 50% in the particle diameter distribution (volume basis) measured by the laser diffraction method. It can be measured using a laser diffraction / scattering particle size distribution measuring apparatus.

Here, in the present invention, the aspect ratio (major axis / minor axis) of the inorganic particles is preferably 1 or more and 10 or less, and more preferably 1 or more and 5 or less.
In the present invention, the “aspect ratio” of the inorganic particles is determined by observing the inorganic particles with an SEM (scanning electron microscope) and orthogonally intersecting the maximum diameter (major axis) and the maximum diameter of any 50 inorganic particles. It can be determined by measuring the particle diameter (minor axis) in the direction and calculating the average value of the ratio of the major axis to the minor axis (major axis / minor axis).
When measuring the volume average particle diameter and aspect ratio of the inorganic particles, for example, the resin is dissolved using a good solvent for the resin contained in the composite material particles and the composite material sheet, or the resin is used. The inorganic particles can be taken out by any method such as thermal decomposition.

[[Content ratio of inorganic particles]]
And the content rate of the inorganic particles in the particles of the composite material is not particularly limited and is preferably 5% by mass or more, preferably 65% by mass or less, and 45% by mass or less. More preferred. This is because, if the content ratio of the inorganic particles is equal to or more than the above lower limit, for example, the composite material sheet obtained by using the composite material particles can exhibit desired characteristics and give better strength. Moreover, if the content rate of an inorganic particle is below the said upper limit, it is because it is easy to give moderate stickiness with the particle | grains of a composite material, and to suppress a blocking resistance more favorably. For example, by using the particles of the composite material, it becomes easier to satisfactorily form a thicker primary composite material sheet.

[[Fibrous carbon material]]
The fibrous carbon material that can be used as the inorganic material is not particularly limited. For example, the fibrous carbon material is obtained by carbonizing carbon nanotubes (hereinafter sometimes referred to as “CNT”), vapor-grown carbon fibers, and organic fibers. Carbon fibers, and their cuts can be used. These may be used individually by 1 type and may use 2 or more types together.
Among the above, as the fibrous carbon material, it is preferable to use a fibrous carbon nanostructure such as CNT, and it is more preferable to use a fibrous carbon nanostructure including CNT. This is because, if a fibrous carbon nanostructure such as CNT is used, for example, the thermal conductivity and strength of the composite material sheet obtained using the composite material particles can be further improved.

-Fibrous carbon nanostructure containing CNT-
Here, the fibrous carbon nanostructure containing CNT that can be suitably used as the fibrous carbon material may be composed only of CNT, or CNT and a fibrous carbon nanostructure other than CNT. It may be a mixture of
And as a suitable property of the fibrous carbon nanostructure containing CNT, it can be made to be the same as that of the property about CNT of Unexamined-Japanese-Patent No. 2006-054113, for example.
Moreover, the preparation of the fibrous carbon nanostructure containing CNTs can be efficiently performed by the super-growth method, for example, according to the description in International Publication No. 2006/011655.

[Content ratio of inorganic material]
And the content rate of the inorganic material in the particle | grains of a composite material is not restrict | limited especially, It is preferable that it is 5 mass% or more, it is preferable that it is 65 mass% or less, and it is 45 mass% or less. More preferred. If the content ratio of the inorganic material is equal to or more than the above lower limit, for example, the composite material sheet obtained using the composite material particles can further exhibit desired properties such as thermal conductivity and can further increase the strength. It is. Moreover, if the content ratio of the inorganic material is less than or equal to the above upper limit, moderate stickiness is imparted by the composite material particles, and the blocking resistance can be more easily suppressed. For example, the use of the composite material particles makes it easier to form a thicker primary composite material sheet.

[Additive]
As an additive which the particle | grains of a composite material can contain arbitrarily, the additive similar to the additive as described in Unexamined-Japanese-Patent No. 2015-227411 can be mentioned, for example.

[Blocking resistance of composite material particles]
The blocking resistance of the composite material particles needs to be 0% or more and 80% or less. The anti-blocking rate of the composite material particles is more preferably 50% or more, and still more preferably 70% or more. If the anti-blocking rate is less than or equal to the above upper limit, the composite material particles exhibit moderate stickiness, and therefore, the composite material particles sandwiched between the two sheet base materials and the two sheet base materials And the composite particles can be subjected to a sufficiently large force during primary pressurization (so-called idling is less likely to occur). Therefore, it is easy to form a thickened primary composite material sheet, and a composite material sheet using the laminate of the primary composite material sheets can be efficiently produced. Here, in the case of forming a thickened primary composite material sheet, generally, the composite material particles are not sufficiently subjected to the primary pressurizing force. It is difficult to orient properly. However, if the anti-blocking rate is made lower than the above upper limit, as described above, the particles of the composite material can receive a large force at the time of primary pressurization. It can be well oriented in the direction.
Further, if the blocking resistance is equal to or higher than the above lower limit, it is excellent in the handleability of the composite material particles, and the reason is not clear, but the surface roughness of the composite material sheet using the composite material particles is excellent, and the composite material It is because a smooth surface can be given to the material sheet. In addition, if the blocking resistance is equal to or higher than the above lower limit, the effect of reducing the thermal resistance value when the composite material sheet, which will be described in detail later, is subjected to the third pressurization is large, and a composite material sheet superior in thermal conductivity can be obtained. It is. Here, it is not clear why the effect of reducing the thermal resistance when the composite sheet is subjected to the third pressurization when the blocking resistance is equal to or higher than the above lower limit. However, in the above case, the composite material sheet using the composite material particles having appropriate powder flowability is not subject to excessive force from the third pressurization, while maintaining good orientation of the inorganic material. As described above, it is assumed that the surface smoothness can be improved.

In addition, in order to adjust the blocking resistance of the composite material particles within the predetermined range, the timing of introducing the inorganic material can be shifted in the preparation of the composite material particles without particular limitation. Specifically, for example, in the preparation of the composite material particles, a part of the inorganic material (hereinafter sometimes referred to as “inorganic particles A”) is added at the time of mixing and kneading, and the remaining inorganic material (hereinafter, referred to as “inorganic particles A”). "Sometimes referred to as" inorganic particles B ") at the time of the above-mentioned pulverization and pulverization. Here, “at the time of mixing and kneading” may be before the start of mixing and kneading, may be during mixing and kneading, and is a continuous time from the start of mixing and kneading to mixing and kneading. There may be. Similarly, “at the time of crushing and crushing” may be before the start of crushing and crushing, may be during crushing and crushing, and before crushing and crushing until crushing and crushing It may be a continuous time.
When the inorganic material is introduced at a different timing as described above, the inorganic material is preferably inorganic particles from the viewpoint of ease of work. In addition, the inorganic material and the inorganic particles may be the same or different when the timing is shifted.
In addition, in order to adjust the anti-blocking rate of the composite material particles within the predetermined range, in the preparation of the composite material particles, the type and content ratio of the resin described above can be appropriately adjusted.

[Particle size of composite material particles]
The particle diameter of the composite material particles is preferably 100 μm or more in terms of volume average particle diameter, more preferably 500 μm or more, preferably 1000 μm or less, and more preferably 850 μm or less. This is because if the particle diameter of the composite material particles is equal to or greater than the lower limit, a primary composite material sheet having a larger thickness can be easily formed when the composite material particles are primarily pressurized. In addition, if the particle diameter of the composite material particles is equal to or greater than the above lower limit, the reason is not clear, for example, the effect of reducing the thermal resistance value when the composite material sheet, which will be described in detail later, is subjected to the third pressure, This is because a composite material sheet superior in thermal conductivity can be obtained. In addition, if the particle diameter of the composite material is equal to or less than the above upper limit, the handleability of the composite material particles is more excellent.

[Composite particle coverage]
Further, in the preparation of the composite material particles, as described above, when the inorganic particles A are added at the time of mixing and kneading and the inorganic particles B are charged at the time of pulverization and pulverization, the following formula (3):
{(Specific surface area of inorganic particles B × mass of inorganic particles B) /
(Specific surface area of composite material particles × mass of composite material particles)} × 100 (3)
Is preferably 20% or more, more preferably 30% or more, preferably 90% or less, and more preferably 60% or less. This is because the particles of the composite material in which the coverage by the inorganic particles B is equal to or more than the above lower limit suppresses excessive stickiness and is excellent in handling properties. The reason is not clear in the case of the composite material particles whose coverage by the inorganic particles B is not more than the above upper limit. For example, the surface roughness of the composite material sheet using the composite material particles is superior, and the composite material sheet This is because a smoother surface can be provided. In addition, if the coverage by the inorganic particles B is equal to or lower than the above upper limit, the reason is not clear. This is because a composite material sheet superior in conductivity can be obtained.
In addition, when the timing of adding the inorganic particles is shifted when preparing the composite material particles, the composite material particles in which all of the inorganic particles B adhere to the surface layer portion of the particle body including the resin and the inorganic particles A are obtained. In some cases (I), a part of the inorganic particles B do not adhere to the surface layer of the particle body, and a powder composition containing the composite particles and the inorganic particles B can be obtained (II). In the present specification, in the above case (II), “the specific surface area of the particles of the composite material” and “the mass of the particles of the composite material” used for the calculation of the coverage are “the ratio as the composite composition”. It can be determined as “average surface area” and “average mass as composite composition”.

<< Method for Preparing Particles of Composite Material >>
The preparation of the composite material particles is not particularly limited, and can be performed, for example, according to the same method as the step of obtaining the composite material particles described above.

  Here, the mixing and kneading methods are not particularly limited, and can be performed using a kneading apparatus such as a kneader, a roll, a Henschel mixer, a Hobart mixer, a high-speed mixer, or a twin-screw kneader. Mixing and kneading may be performed in the presence of a solvent such as ethyl acetate and methyl ethyl ketone. Furthermore, the mixing and kneading temperature can be, for example, 5 ° C. or more and 150 ° C. or less.

The crushing and pulverizing methods are not particularly limited, and a cutter mill, a hammer mill, a bead mill, a vibration mill, a meteor type ball mill, a sand mill, a ball mill, a roll mill, a three-roll mill, a jet mill, a high-speed rotary pulverizer, etc. Can be used. Among these, it is desirable to use a cutter mill or a hammer mill.
The pulverization conditions may be adjusted as appropriate according to the desired particle size after pulverization, such as a pulverizer and pulverization strength.

Furthermore, when preparing the particles of the composite material, for example, when using the inorganic particles A and the inorganic particles B described above as the inorganic material, the addition ratio of the inorganic particles B depends on the content of the inorganic particles A and the addition of the inorganic particles B. The total amount is preferably 10% by mass or more, more preferably 20% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and 35% by mass or less. More preferably. This is because if the addition ratio of the inorganic particles B is equal to or more than the above lower limit, the particles of the composite material can be prevented from being excessively sticky, and the handleability of the particles of the composite material can be further improved. Moreover, if the addition ratio of the inorganic particles B is less than or equal to the above upper limit, for example, the composite material sheet obtained using the composite material particles can exhibit more desirable characteristics such as thermal conductivity.
In addition, the reason why the excessive stickiness of the particles of the composite material can be suppressed by setting the addition ratio of the inorganic particles B to the above lower limit or more is not clear. However, when the composite mixture containing the resin and the inorganic particles A is pulverized and pulverized, the inorganic particles B are delayed from the inorganic particles A, particularly when they are pulverized and pulverized. This is presumably because the inorganic particles B satisfactorily cover the surface layer portion of the particle body containing the resin and the inorganic particles A.

<Sheet base material>
At least one of the sheet base materials used in the pressurizing method of the present invention needs to have a peeling force within a predetermined range. When the above-mentioned predetermined composite material particles are sandwiched between the sheet base materials and subjected to primary pressure, if the at least one sheet base material does not have a peeling force within a predetermined range, the thickened primary composite material sheet is satisfactorily obtained. Cannot be formed. And a composite material sheet cannot be efficiently manufactured using the laminated body of the said primary composite material sheet.

<< Peeling power of sheet base material >>
The peel strength of the sheet base material is such that the peel strength of at least one of the two sheet base materials sandwiching the composite material particles described above during primary pressurization is 0.03 N / cm to 4.0 N / Must be less than cm. The peel strength of the sheet base material is preferably 0.30 N / cm or more, preferably 3.00 N / cm or less, of at least one of the two sheet base materials. It is preferable. Further, the sheet base material is more preferably 0.03 N / cm or more, more preferably less than 4.0 N / cm, for both of the two sheet base materials sandwiching the composite material particles described above, More preferably, it is 3.00 N / cm or less.
If the peeling force of at least one sheet base material is equal to or greater than the above lower limit, the friction between the sheet base material and the composite material particles sandwiched between the sheet base material is increased, and the sheet base during the primary pressurization is increased. The material can exert a sufficiently large force on the particles of the composite material (so-called slippage is unlikely to occur). Therefore, it is easy to form a thickened primary composite material sheet, and a composite material sheet using the laminate of the primary composite material sheets can be efficiently produced. Here, when forming a thick primary composite sheet, generally, the sheet base material is difficult to give sufficient force to the composite material particles, so the inorganic material contained in the composite material particles is in a desired direction. It is difficult to orient properly. However, as long as the peeling force of at least one sheet base material is equal to or greater than the above lower limit, as described above, the sheet base material can give a large force to the particles of the composite material. It can be well oriented in the desired direction.
In addition, if the peel strength of the sheet base material is less than the above upper limit, the primary composite material sheet and the sheet base material are sufficiently prevented from adhering when the sheet base material is peeled off from the primary pressurized composite material particles. In addition, the primary composite material sheet can be favorably obtained without damaging the sheet shape.
In addition, the raw material and peeling force of two sheet base materials may be the same, and may differ.

<Primary pressurization>
In the primary pressurization, the above-described predetermined composite material particles are pressed in a state where at least one of the two is sandwiched between the above-described sheet base materials having the predetermined peeling force. And by carrying out primary pressurization in this way, the thickened primary composite material sheet can be obtained favorably.

<< Pressurization method >>
The primary pressurization is not particularly limited, and can be performed using a known pressurizer such as a press machine or a roll machine. Especially, it is preferable to perform primary pressurization with a roll machine from a viewpoint of controlling the thickness of a primary composite material sheet favorably.
In addition, the thickness of a primary composite material sheet | seat can be favorably controlled by adjusting a pressure, the roll gap | interval of a roll machine, etc., for example. For example, when primary pressurization is performed using a roll machine, the roll linear pressure can be 10 kg / cm or more and 100 kg / cm or less.

<< Thickness of primary composite sheet >>
And the thickness of the primary composite material sheet obtained by primary pressurization is preferably 1.0 mm or more, more preferably 1.2 mm or more, 3.0 mm or less, preferably 2.0 mm or less. be able to. If the thickness of the primary composite material sheet is increased to the above lower limit or more, for example, when a composite material sheet is produced using a laminate of the primary composite material sheet, the number of the primary composite material sheets in the laminate is increased. Since it can reduce, the manufacturing efficiency of a composite material sheet can be raised more. In addition, when the thickness of the primary composite material sheet exceeds the above upper limit, the difficulty of forming the sheet increases, and it is difficult to properly orient the inorganic material contained in the primary composite material sheet in a desired direction. Will also increase. Thus, in general, when forming a sheet by pressurizing the particles of the composite material, the larger the thickness of the sheet, the more uniformly the entire pressurizing particle is difficult to transmit a large pressing force. Sheet formation becomes difficult. However, in the present invention, the blocking resistance of the composite material particles is suppressed within a predetermined range, and at least one peeling force of the sheet base material sandwiching the composite material particles is set within the predetermined range. For example, even when the thickness of the primary composite material sheet is relatively thick at 1.0 mm or more, the primary composite material sheet can be satisfactorily formed.

<< Specific gravity of primary composite sheet >>
Further, the specific gravity of the primary composite material sheet obtained by the primary pressurization is preferably 1.30 or more, more preferably 1.40 or more, and preferably 1.65 or less. If the specific gravity of the primary composite material sheet is equal to or higher than the above lower limit, it can be said that the primary composite material sheet is formed while sufficiently applying primary pressurizing force to the composite material particles. Therefore, it is possible to suppress the slip of the composite material particles during the primary pressurization and form a thick composite material sheet, and to better align the inorganic material in the composite material sheet. Because it can be made. Further, if the specific gravity of the primary composite material sheet exceeds the above upper limit, it can be said that the composite material particles are excessively subjected to the primary pressurizing force, and thus it is difficult to ensure a large thickness of the composite material sheet.
In the present invention, the specific gravity of the primary composite material sheet can be appropriately adjusted by adjusting the conditions of primary pressurization such as roll gap and roll linear pressure.

  And in the obtained primary composite material sheet, since the inorganic material is well oriented in the in-plane direction, for example, when a particulate carbon material and a fibrous carbon material are used as the inorganic material, the primary composite material sheet It is inferred that the heat transfer path of the particulate carbon material and the fibrous carbon is well formed in the in-plane direction. That is, it is inferred that the obtained primary composite material sheet is excellent in thermal conductivity in the in-plane direction.

(Production method of composite material sheet)
The manufacturing method of the composite material sheet of the present invention includes a step of obtaining a primary composite material sheet according to the pressing method described above, a step of obtaining a laminate of the obtained primary composite material sheet, and slicing the obtained laminate. Obtaining a composite sheet. If the laminated body of the primary composite material sheet obtained according to the predetermined pressing method described above is used, the composite material sheet can be produced efficiently. In addition, the method for producing a composite material sheet of the present invention further includes a step of secondarily pressing the obtained laminate to obtain a compressed laminate prior to the step of obtaining the composite material sheet, thereby obtaining a composite material sheet. It is preferable to slice the compressed laminate in the process. Moreover, it is preferable that the manufacturing method of the composite material sheet | seat of this invention further has the process of compressing by compressing the obtained composite material sheet | seat after the process of obtaining the said composite material sheet | seat.

<Step of obtaining a primary composite material sheet>
In the step of obtaining the primary composite material sheet, the primary composite material sheet is obtained according to the pressing method described above. And the thickness of the obtained primary composite material sheet can be made into the suitable thickness as mentioned above in the paragraph of primary pressurization, and the effect can also be made the same.

<Step of obtaining a laminate>
In the step of obtaining a laminated body, a plurality of primary composite material sheets obtained in the step of obtaining the primary composite material sheet are laminated in the thickness direction, or the primary composite material obtained in the step of obtaining the primary composite material sheet. The sheet is folded or rolled to obtain a laminate.

<< Lamination method >>
Formation of the laminated body by lamination | stacking of a primary composite material sheet is not specifically limited, You may carry out using a lamination apparatus, and may carry out manually. Moreover, formation of the laminated body by folding of a primary composite material sheet is not specifically limited, It can carry out by folding a primary composite material sheet by fixed width using a folder. Furthermore, the formation of the laminate by winding the primary composite sheet is not particularly limited, and by rolling the primary composite sheet around an axis parallel to the short direction or the longitudinal direction of the primary composite sheet. It can be carried out.

Here, usually, in the step of obtaining a laminate, the adhesive force between the surfaces of the primary composite material sheet is sufficiently obtained by the pressure at the time of laminating the primary composite material sheet or the pressure at the time of folding or winding. However, when the adhesive strength is insufficient or when it is necessary to sufficiently suppress delamination of the laminate, the laminate may be formed with the surface of the primary composite material sheet slightly dissolved with a solvent. Then, the laminate may be formed in a state where an adhesive is applied to the surface of the primary composite material sheet or in a state where an adhesive layer is provided on the surface of the primary composite material sheet.
In addition, it does not specifically limit as a solvent used when melt | dissolving the surface of a primary composite material sheet, The known solvent which can melt | dissolve the resin component contained in a primary composite material sheet can be used. Moreover, it does not specifically limit as an adhesive agent apply | coated to the surface of a primary composite material sheet, A commercially available adhesive agent and adhesive resin can be used. Furthermore, the adhesive layer provided on the surface of the primary composite material sheet is not particularly limited, and a double-sided tape or the like can be used.

[Number of layers]
And in the process of obtaining a laminated body, when the primary composite material sheet thickened as described above is used, the number of laminated layers, the number of folds, or the number of wrinkles can be reduced. Can be formed. For example, if the thickness of the primary composite material sheet is doubled from 0.5 mm to 1.0 mm, the number of laminates can generally be halved, so the laminate and composite material sheet are formed. Efficiency can be doubled.

  In addition, in a laminate obtained by laminating, folding, or winding a primary composite material sheet, it is assumed that inorganic materials such as particulate carbon materials and fibrous carbon materials are oriented in a direction substantially perpendicular to the laminating direction. The

<Step of obtaining a compressed laminate>
In the step of obtaining a compressed laminate that can be further included in the method for producing a composite material sheet of the present invention, the laminate obtained in the step of obtaining the laminate is secondarily pressed in the laminating direction to compress the compressed laminate. obtain. If the laminate is further subjected to secondary pressurization in this way, in the compression laminate, the inorganic material can be favorably oriented in the direction substantially perpendicular to the lamination direction (the in-plane direction of the primary composite material sheet). The sheet can provide desired properties such as excellent thermal conductivity.

<< Secondary pressurization >>
In the secondary pressurization, the laminate of the primary composite sheet described above is pressed in the laminating direction to compress the laminate. The secondary pressurization of the laminate is not particularly limited and can be performed by the same method as the primary pressurization described above. Among them, it is preferable to use a press machine from the viewpoint of workability.
Here, from the viewpoint of suppressing delamination, for example, the press pressure of secondary pressurization can be set to 0.05 MPa or more and 1.0 MPa or less, the pressurization temperature is 20 ° C. or more and 150 ° C. or less, and the pressurization time. Can be 1 minute or more and 30 minutes or less.

[Decrease rate of laminate height]
Here, the secondary pressurization is preferably such that the rate of reduction in the height from the laminate to the compression laminate (decrease in the laminate height) calculated by the above-described formula (1) is 1% or more. It is more preferably 3% or more, further preferably 10% or more, preferably 30% or less, and more preferably 20% or less. If the reduction rate of the laminate height is equal to or greater than the above lower limit, the laminated primary composite sheets can be bonded better and delamination can be further suppressed, and the direction in which the inorganic material is substantially orthogonal to the laminate direction of the laminate In order to achieve better orientation in the (in-plane direction of the primary composite material sheet), for example, a conductive path made of, for example, a particulate carbon material and a fibrous carbon material is more favorably formed. Therefore, anisotropy of physical properties such as thermal conductivity can be further imparted in a direction substantially perpendicular to the lamination direction of the laminate. Further, if the reduction rate of the laminate height is equal to or less than the above upper limit, for example, good thermal conductivity can be maintained without excessively pressurizing the laminate and cutting the conductive path of the inorganic material. .

<Step of obtaining a composite material sheet>
In the step of obtaining a composite material sheet, the laminate obtained in the step of obtaining the laminate is sliced at an angle of 45 ° or less with respect to the lamination direction (“composite material sheet before tertiary pressurization”). May be called). Further, in the step of obtaining the composite material sheet, when slicing the laminate, it is preferable to slice the compressed laminate obtained in the step of obtaining the compressed laminate at an angle of 45 ° or less with respect to the lamination direction.

<< Slicing method >>
A method for slicing a laminate such as a compression laminate is not particularly limited, and examples thereof include a multi-blade method, a laser processing method, a water jet method, and a knife processing method. Among these, the knife processing method is preferable in that the thickness of the composite material sheet is easily uniformed. Moreover, as a cutting tool when slicing a laminate such as a compression laminate, it is not particularly limited, and a slicing member having a smooth board surface having a slit and a blade protruding from the slit (for example, Canna or slicer with a sharp blade can be used.

In addition, from the viewpoint of enhancing desired characteristics such as thermal conductivity of the composite material sheet, the angle at which the laminate such as the compression laminate is sliced is preferably 30 ° or less with respect to the lamination direction. On the other hand, it is more preferably 15 ° or less, and preferably about 0 ° with respect to the stacking direction (that is, the direction along the stacking direction).
Moreover, from the viewpoint of easily slicing a laminate such as a compressed laminate, the temperature of the laminate such as a compressed laminate when slicing is preferably −20 ° C. or more and 40 ° C. or less, and preferably 10 ° C. or more and 30 ° C. More preferably, it is as follows. Furthermore, from the viewpoint of easily slicing a laminate such as a compression laminate, the laminate such as a compression laminate to be sliced is preferably sliced while applying pressure in a direction orthogonal to the lamination direction (lamination side surface). It is more preferable to slice while applying a pressure of 0.1 MPa or more and 0.5 MPa or less in a direction (lamination side surface) perpendicular to the lamination direction.

<< Specific gravity of composite material sheet before tertiary pressurization >>
Here, the specific gravity of the composite material sheet before performing the third pressurization described later is preferably 1.40 or more, more preferably 1.50 or more, and preferably 2.00 or less, It is more preferable that it is 1.80 or less. If the specific gravity of the composite material sheet obtained after the secondary pressing and slicing of the laminate before the third pressurization is equal to or higher than the above lower limit, for example, a sufficient force of the secondary pressing is applied to the laminate. It can be said that the composite material sheet is formed using the compression laminate. Therefore, a conductive path formed by orienting inorganic materials such as particulate carbon materials and fibrous carbon materials in the thickness direction is formed more satisfactorily, and anisotropy of physical properties such as thermal conductivity is formed in the thickness direction of the composite material sheet. It is because it can further provide. In addition, if the specific gravity of the composite material sheet before the third pressurization exceeds the above upper limit, the laminate is excessively subjected to the secondary pressurization force, the conductive path of the inorganic material is cut, and the thermal conductivity of the composite material sheet, etc. This is because there is a possibility that the characteristics of the above may deteriorate.
In the present invention, the specific gravity of the composite material sheet before the third pressurization can be appropriately adjusted by adjusting the conditions of the second pressurization, for example.

  In the obtained composite material sheet, the inorganic material is well oriented in the thickness direction, and it is presumed that the composite material sheet is particularly excellent in desired characteristics such as thermal conductivity in the thickness direction.

<Step of compressing by third pressure>
In the step of compressing by third pressurization which can be further included in the method for producing a composite material sheet of the present invention, the composite material sheet obtained according to the above-described production method is further compressed by third pressurization in the thickness direction. If the composite material sheet is tertiary-pressurized in this way, the surface smoothness of the composite material sheet can be enhanced. Therefore, for example, when the composite material sheet is attached to an arbitrary adherend and used, the adhesion between the composite material sheet and the adherend is improved, and the composite material sheet exhibits more desirable characteristics such as thermal conductivity. obtain.
In addition, the composite material sheet obtained through the step of compressing by third pressurization may be referred to as “composite material sheet after third pressurization”.

<< Tertiary pressurization >>
The tertiary pressurization of the composite material sheet is not particularly limited and can be performed by the same method as the primary pressurization described above. Among them, it is preferable to use a press machine from the viewpoint of workability. For example, from the viewpoint of giving good smoothness to the surface without impairing the physical properties of the composite material sheet, the conditions of the tertiary pressurization are a temperature of 20 ° C. or more and 100 ° C. or less, a press pressure of 0.1 MPa or more and 50 MPa or less, and a press time. It can be set to 5 seconds or more and 5 minutes or less.

[Reduction rate of sheet thickness]
Here, in the third pressurization, the reduction rate of the sheet thickness calculated by the above formula (2) is preferably 1% or more, more preferably 5% or more, and 40% or less. Is preferably 30% or less, and more preferably 20% or less. The surface of the resulting composite material sheet can be smoothed if the composite material sheet is subjected to tertiary pressurization at a sheet thickness reduction rate that is equal to or greater than the above lower limit. For example, the composite material sheet is used by sticking to an arbitrary adherend. In this case, the adhesion between the composite material sheet and the adherend increases. As a result, the desired characteristics of the composite material sheet can be exhibited better. Further, if the sheet thickness reduction rate is suppressed to the upper limit or less, for example, the orientation of the inorganic material that is well oriented in the thickness direction of the composite material sheet is maintained, and desired characteristics in the thickness direction of the composite material sheet are maintained. It is because it can ensure favorable.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%” and “part” representing amounts are based on mass unless otherwise specified.
In the examples and comparative examples, the density, volume average particle diameter and specific surface area of the particles of the inorganic material and the composite material; the blocking resistance of the particles of the composite material; the peeling force of the sheet substrate; the laminate and the compression laminate Specific gravity of primary composite sheet and composite sheet before tertiary pressing; thickness of primary composite sheet and composite sheet before and after tertiary pressing; surface roughness Sz and heat of composite sheet before and after tertiary pressing Each of the resistance values was measured or evaluated according to the following method.

<Density>
The density of the particles of the inorganic material and the composite material was measured for each using a true density measuring instrument (product name “MAT-7000” manufactured by Seishin Enterprise Co., Ltd.). The measurement temperature was 25 ° C., the sample mass was 2 g, the solvent was N-butanol, and the degassing time was 10 minutes. Here, regarding the density of the composite material particles, the total amount of the inorganic particles B used at the time of preparing the composite material particles is included (that is, there are inorganic particles B that did not constitute the composite material particles). In this case, the average value (g / m ³ ) of the powder composition including the inorganic particles B was calculated.
And the obtained density was used for calculation of the specific surface area mentioned later.

<Volume average particle diameter>
The volume average particle size (m) of the inorganic material and composite material particles was measured using a laser diffraction / scattering particle size distribution measuring apparatus (product name “Microtrack MT3300EX-II” manufactured by Nikkiso). Specifically, particle size distributions were obtained for the inorganic material and composite material particles. Then, the center particle diameter (D50) at which the cumulative volume calculated from the small diameter side in the obtained particle diameter distribution (volume basis) is 50% was calculated as the volume average particle diameter of the inorganic material and composite material particles. . In addition, about the volume average particle diameter of the particle | grains of a composite material, the total input amount of the inorganic particle B used at the time of preparation of the particle | grains of a composite material was included (that is, the inorganic particle B which did not comprise the particle | grains of a composite material). When present, it was calculated as an average value (m) (as a whole powder composition including the inorganic particles B).
And the obtained volume average particle diameter was used for calculation of the specific surface area mentioned later.

<Specific surface area>
The specific surface area of the particles of the inorganic material and the composite material is expressed by the following formula (4) using the values of the density and the volume average particle diameter calculated as described above:
Specific surface area (m ² / g) =
6 / (density (g / m ³ ) × volume average particle diameter (m)) (4)
Sought according to.
And the obtained specific surface area was used for calculation of the coverage represented by Formula (3) mentioned above.

<Blocking resistance>
The blocking resistance of the particles of the composite material was evaluated by a sieving method. Specifically, 80 g of the composite material particles sieved with a mesh having a mesh size of 1.4 mm were put into the beaker from the same height as the upper mouth of the 200 mL glass beaker without applying pressure. Next, a 400 g weight having the same inner diameter as the inner diameter of the beaker charged with the composite material particles was slowly put on the composite material particles in the beaker. One minute after the weight was placed, the weight was removed, and the composite material particles attached to the outer bottom surface of the weight were removed in a beaker so that there was no loss of the composite material particles.
Subsequently, a mesh having a wire diameter of 1.1 mm, a mesh opening of 11.3 mm, and a size larger than the upper mouth (a square having a side of 150 mm) is placed on the upper mouth of the beaker containing the particles of the composite material. Further, a bat was placed on the mesh. Next, the upper and lower surfaces were turned upside down while fixing the beaker, mesh, and bat, and the beaker was pulled up 15 cm from the mesh. Then, the mesh was slowly lifted 5 cm, and the composite particles remaining on the mesh after 1 minute from the lift were transferred to another bat. If the composite material particles hardly fall from the bottom of the beaker even when the top and bottom surfaces are turned upside down, gently tap the outside of the beaker with a spatula etc. without separating the beaker from the mesh. Dropped on the mesh. When the composite material particles adhered to the inside of the beaker when the beaker was pulled up, the composite material particles were dropped on the mesh by tapping the outside of the beaker with a spatula or the like.
And the following formula (5):
Anti-blocking rate (%) = (mass of composite particles passing through mesh (g)) / (mass of composite particles remaining on mesh (g) + mass of composite particles passing through mesh ( g)) × 100% (5)
Thus, the anti-blocking rate of the composite material particles was determined. The larger the obtained value, the more sticky the particles of the composite material, and the more difficult it is to block.

<Peeling force>
The sheet substrate was cut into a 25 mm × 125 mm strip and used as a test specimen. Next, a polyester pressure-sensitive adhesive tape (manufactured by Nitto Denko, trade name “No. 31B”) was attached to the surface of the test body that was in contact with the composite particles. Then, using a tensile tester (manufactured by Shimadzu Corporation, product name “Autograph AG-IS 20 kN”), the peel force (N / cm) between the test specimen and the polyester adhesive tape attached to the test specimen was used. In accordance with JIS Z-0237, the measurement was performed under the conditions of a peeling speed of 500 mm / min and a peeling angle of 180 °.

<Height>
The height (mm) of the laminate and the compressed laminate was determined visually by measuring the height of the laminate with a ruler.

<Specific gravity>
The specific gravity of the primary composite material sheet and the composite material sheet before the third pressurization was measured using an automatic hydrometer (manufactured by Toyo Seiki Co., Ltd., product name “DENSIMTER-H”).

<Thickness>
The thicknesses of the primary composite material sheet and the composite material sheet before and after the third pressurization were measured using a film thickness meter (manufactured by Mitutoyo, product name “Digimatic Indicator ID-C112XBS”). And it measured about five arbitrary places on each sheet | seat surface, and made the average value of the measured value the thickness (mm) of each sheet | seat.

<Surface roughness Sz>
The surface roughness Sz of the composite material sheet before and after the third pressurization was measured using a three-dimensional shape measuring machine (manufactured by Keyence Corporation, product name “One-shot 3D measurement macroscope”). Here, each sheet cut into a substantially square having an arbitrary size of 1 cm square or more was used as a sample. The analysis range was 1 cm × 1 cm, and the three-dimensional shape was measured for the surface (pressurized surface) of the sample. Further, the measurement result of the three-dimensional shape was further subjected to filter processing (2.5 mm) with software, and the surface roughness Sz (μm) component was automatically extracted by removing the waviness component.
In the present invention, the “surface roughness Sz” is the maximum height (distance in the height direction connecting the highest point and the lowest point on a certain surface) defined in the international standard ISO 25178, It is an index for evaluating the roughness state of the certain surface.

<Thermal resistance value>
The thermal resistance value of the composite material sheet before and after the third pressurization was measured by a steady method using a thermal resistance measuring device (product name “resin material thermal resistance measuring device” manufactured by Hitachi Technology & Service Co., Ltd.). Here, each sheet cut into a square of 1 cm square was used as a sample, and the thermal resistance value (° C./W) under 0.05 MPa, which is a relatively low pressure, was measured. In addition, the sample temperature at the time of measurement was 50 degreeC. The smaller the thermal resistance value, the more excellent the thermal conductivity of the composite material sheet. For example, it indicates that the heat dissipation characteristic is excellent when the composite sheet is interposed between the heat generator and the heat radiator.

Example 1
<Preparation of fibrous carbon nanostructure containing CNT>
According to the description in WO 2006/011655, a fibrous carbon nanostructure containing CNTs was obtained by the super-growth method.
The obtained fibrous carbon nanostructure had a BET specific surface area of 800 m ² / g. Further, as a result of measuring the diameter of 100 randomly selected fibrous carbon nanostructures using a transmission electron microscope, the average diameter (Av) was 3.3 nm, and the sample standard deviation (σ) of the diameter was 3 The value (3σ) multiplied by 1.9 nm was 1.9 nm, and the ratio (3σ / Av) was 0.58. Further, the obtained fibrous carbon nanostructure was mainly composed of single-walled CNTs.

<Preparation of an easily dispersible assembly of fibrous carbon nanostructures>
<< Preparation of dispersion >>
400 mg of the fibrous carbon nanostructure obtained above as a fibrous carbon material was weighed, mixed in 2 L of methyl ethyl ketone as a solvent, and stirred for 2 minutes with a homogenizer to obtain a crude dispersion. Next, using a wet jet mill (product name “JN-20”, manufactured by Joko Co., Ltd.), the obtained coarse dispersion is passed through a 0.5 mm flow path of the wet jet mill at a pressure of 100 MPa for two cycles. Then, the fibrous carbon nanostructure was dispersed in methyl ethyl ketone. And the dispersion liquid of solid content concentration 0.20 mass% was obtained.
<< Removal of solvent >>
Thereafter, the dispersion obtained above was filtered under reduced pressure using Kiriyama filter paper (No. 5A) to obtain a sheet-like easily dispersible aggregate.

<Preparation of composite material particles>
100 parts of a thermoplastic fluororesin (trade name “DAIEL G-101”, manufactured by Daikin Industries, Ltd.) that is liquid under normal temperature and pressure as the resin, and expanded graphite as inorganic particles A among the inorganic materials (ITO Graphite Industries) 30 parts by trade name “EC-100”, volume average particle size: 190 μm), and 0.1 part of an easily dispersible aggregate of fibrous carbon nanostructures as a fibrous carbon material, This was put into a Hobart mixer (manufactured by Kodaira Seisakusho, product name “ACM-5LVT type”, capacity: 5 L). And it heated at 80 degreeC, the composite mixture was obtained by stirring and mixing for 30 minutes.
Next, 20 parts of the obtained composite mixture and expanded graphite as inorganic particles B among inorganic materials (manufactured by Ito Graphite Industries Co., Ltd., trade name “EC-100”, volume average particle diameter: 190 μm), The product was put into a free speed mill (product name “FS20” manufactured by LaboNect Co., Ltd.) all at once. And the particle | grains of the composite material were obtained by crushing for 60 second by speed memory = 100.
And about the particle | grains of the obtained composite material, according to the above-mentioned method, the density, the volume average particle diameter, the specific surface area, and the blocking resistance were measured. The results are shown in Table 1.

<Formation of primary composite material sheet>
Next, 100 g of the obtained composite material particles are sandwiched between two fluorine films (made by Daikin Industries, trade name “Neofluon PFA film”, thickness: 50 μm, peeling force: 0.30 N / cm) as a sheet base material. It is. Then, the sandwiched composite material particles are roll-formed (primary pressurization) under the conditions of a roll gap of 1500 μm, a roll temperature of 50 ° C., a roll linear pressure of 50 kg / cm, and a roll speed of 1 m / min to obtain a thickness of 1.449 mm. A primary composite sheet with a specific gravity of 1.50 was obtained.
In addition, the peelability between the primary composite material sheet obtained by the primary pressure and the sheet base material was good.
And about the obtained primary composite material sheet, specific gravity and thickness were calculated | required according to the above-mentioned method. The results are shown in Table 1.

<Formation of laminate>
The obtained primary composite material sheet was cut into a length of 6 cm, a width of 6 cm, and a thickness of 1.449 mm, and 33 sheets were laminated in the thickness direction to obtain a laminate having a height of 4.78 cm.
And about the obtained laminated body, the height was calculated | required according to the above-mentioned method.

<Formation of compression laminate>
Next, the obtained laminate is compressed by applying a secondary pressure (pressing) in the laminating direction at a temperature of 120 ° C. for 1 minute at a pressure of 0.1 MPa, so that the compressed laminate has a height of about 4.16 cm. Got. That is, the reduction rate of the laminate height due to the secondary pressurization was 13%.
In addition, at the time of the secondary pressurization, the laminate is arranged so that the pressure applied to the laminate does not escape in the direction perpendicular to the lamination direction which is the pressure direction (in other words, the in-plane direction of the primary composite material sheet). The four laminated side surfaces other than the pressure top surface and the pressure bottom surface were surrounded by a resin cover. In this way, the laminated body was prevented from being deformed in a direction substantially perpendicular to the laminating direction with the secondary pressurization.
And the height was calculated | required about the obtained compression laminated body according to the above-mentioned method. The results are shown in Table 1.

<Formation of composite material sheet before tertiary pressurization>
Laminate using the slicer for woodworking (manufactured by Marunaka Steel Co., Ltd., trade name “Super Finished Planer Supermechanism S”) while pressing the laminated side of the resulting compressed laminate at a pressure of 0.1 MPa. Sliced at an angle of 0 degrees with respect to the direction (in other words, sliced in the normal direction of the main surface of the laminated primary composite sheet), and the tertiary of 6 cm in length, 6 cm in width, 147 μm in thickness and 1.47 in specific gravity A composite material sheet before pressing was obtained. Here, as a knife of a woodworking slicer, two single blades contact each other on the opposite sides of the cutting blade, the leading edge of the front blade edge is 0.10 mm higher than the leading edge of the back blade edge, the slit portion A two-blade knife having a protrusion length of 0.16 mm and a front blade angle of 21 ° was used.
And about the obtained composite material sheet before the third pressurization, according to the above-mentioned method, specific gravity, thickness, surface roughness Sz, and thermal resistance value were measured. The results are shown in Table 1.

<Formation of composite material sheet after tertiary pressurization>
Using the press machine (made by Shinto Kogyo Co., Ltd., product name “Precision Hot Press CYPT-20”), the composite sheet before the third pressurization obtained above was pressed at a temperature of 25 ° C., a pressure of 5 MPa, The composite material sheet after the third pressurization was obtained by performing the third pressurization in the thickness direction and compressing under the condition of 30 seconds.
The thickness of the composite material sheet subjected to the third pressurization was 126 μm, and the reduction rate of the sheet thickness due to the third pressurization was 14.3%.
And about the obtained composite material sheet after the third pressurization, according to the above-mentioned method, the surface roughness Sz and the thermal resistance value were measured. The results are shown in Table 1.

(Example 2)
In the preparation of the composite material particles, the amount of expanded graphite as inorganic particles A was changed to 35 parts, the amount of expanded graphite as inorganic particles B was changed to 15 parts, and the speed memory of the free speed mill = 40 The composite material particles, the primary composite material sheet, the laminate, the compression laminate, and the composite material sheet before and after the third pressurization having the properties shown in Table 1 are obtained in the same manner as in Example 1 except for crushing for 30 seconds. Manufactured.
And it measured like Example 1. The results are shown in Table 1.

(Example 3)
In the formation of the primary composite material sheet, as a sheet base material, two sand mat pets subjected to sand blasting treatment (product name “Emblet (registered trademark) PTHA-50” manufactured by Unitika, thickness: 75 μm, peeling force: 2 .3 N / cm) in the same manner as in Example 1 except that the composite particles having the properties shown in Table 1, primary composite sheet, laminate, compression laminate, and composite material before and after the third pressurization A sheet was produced.
And it measured like Example 1. The results are shown in Table 1.

Example 4
In the formation of the primary composite material sheet, as a sheet base material on the upper surface, a release-treated PET film (manufactured by Toray Film Co., Ltd., trade name “Celapeel® BX8”, thickness: 75 μm, peeling force: 0.03 N / Cm), and a sand mat pet (product name “Embret (registered trademark) PTHA-50” manufactured by Unitika), thickness: 75 μm, peel strength: 2.3 N / In the same manner as in Example 2 except that (cm) was used, composite particles having the properties shown in Table 1, primary composite sheet, laminate, compression laminate, and composite material sheet before and after tertiary pressurization were produced. did. For convenience, the sheet base disposed on the upper side of the composite material particles during the primary pressurization is referred to as “upper surface”, and the sheet base disposed on the lower side of the composite material particles is referred to as “lower surface”. In producing the effects of the present invention, there is no particular distinction between the upper surface and the lower surface.
And it measured like Example 1. The results are shown in Table 1.

(Example 5)
In the formation of the primary composite material sheet, as a sheet base material, two sand mat pets subjected to sand blasting treatment (product name “Emblet (registered trademark) PTHA-50” manufactured by Unitika, thickness: 75 μm, peeling force: 2 .3 N / cm) in the same manner as in Example 2 except that the composite particles having the properties shown in Table 1, primary composite sheet, laminate, compression laminate, and composite material before and after the third pressurization are used. A sheet was produced.
And it measured like Example 1. The results are shown in Table 1.

(Comparative Example 1)
In the formation of the primary composite material sheet, two PET films subjected to a release treatment (manufactured by Fujiko Co., Ltd., release film, thickness: 50 μm, peel force: 0.02 N / cm) were used as the sheet base material. Except that, composite material particles having the properties shown in Table 1 were prepared in the same manner as in Example 1. An attempt was made to form a primary composite material sheet in the same manner as in Example 1, but the sheet could not be formed.
And it measured like Example 1. The results are shown in Table 1.

(Comparative Example 2)
In the formation of the primary composite material sheet, two PET films subjected to a release treatment (manufactured by Fujiko Co., Ltd., release film, thickness: 50 μm, peel force: 0.02 N / cm) were used as the sheet base material. Except that, composite material particles having the properties shown in Table 1 were prepared in the same manner as in Example 2. An attempt was made to form a primary composite material sheet in the same manner as in Example 1, but the sheet could not be formed.
And it measured like Example 1. The results are shown in Table 1.

(Comparative Example 3)
In the formation of the primary composite material sheet, as the sheet base material, two PET films subjected to the release treatment (manufactured by Fujiko Co., Ltd., release film, thickness: 50 μm, peeling force: 0.02 N / cm) are used. By changing the roll gap to 500 μm, a primary composite material sheet having a thickness of 0.447 mm and a specific gravity of 1.67 was obtained. Further, in the formation of the laminate, the number of the primary composite material sheets was changed to 100. Further, the same as in Example 2 except that the compression laminate was not formed (secondary pressurization of the laminate) and the composite material sheet was not formed after the third pressurization (third pressurization of the composite material sheet). Thus, composite material particles having the properties shown in Table 1, a primary composite material sheet, a laminate, and a composite material sheet before tertiary pressurization were produced.
And it measured like Example 1. The results are shown in Table 1.

(Comparative Example 4)
In the preparation of the composite material particles, composite material particles having the properties shown in Table 1 were prepared in the same manner as in Example 1 except that the composite material particles were obtained by the following method. An attempt was made to form a primary composite material sheet in the same manner as in Example 1, but the sheet could not be formed.
And it measured like Example 1. The results are shown in Table 1.
<Preparation of composite material particles>
45 parts of a thermoplastic fluororesin that is liquid under normal temperature and normal pressure (made by Daikin Industries, Ltd., trade name “DAIEL G-101”) as a resin, and a thermoplastic fluororesin that is solid under normal temperature and normal pressure (manufactured by Daikin Industries, Ltd.) 40 parts of trade name “DAIEL G-704BP”) and expanded graphite as a particulate carbon material which is inorganic particles A (trade name “EC-50” manufactured by Ito Graphite Industries Co., Ltd.), volume average particle diameter: 250 μm ), 0.1 part of an easily dispersible aggregate of fibrous carbon nanostructures as a fibrous carbon material, and sebacic acid ester (made by Daihachi Chemical Industry Co., Ltd., trade name “ 5 parts of DOS ") was stirred and mixed for 5 minutes in the presence of 100 parts of ethyl acetate as a solvent using a Hobart mixer (manufactured by Kodaira Manufacturing Co., Ltd., product name" ACM-5LVT type "). Next, the mixture in the Hobart mixer was vacuum degassed for 30 minutes, and ethyl acetate was removed simultaneously with the degassing. And the particle | grains of the composite material were obtained by crushing the mixture which removed ethyl acetate for 10 second using the crusher (free speed mill mentioned above), without adding the inorganic particle B. FIG.

(Comparative Example 5)
In the formation of the primary composite sheet, two sheet of PET films (Toyobo, trade name “Toyobo Ester (registered trademark) film E5000” manufactured by Toyobo, thickness: 50 μm, release force: 4) are used as the sheet base material. The composite material particles having the properties shown in Table 1 were prepared in the same manner as in Example 1 except that 0 N / cm) was used. And when the primary composite material sheet was formed like Example 1, the primary composite material sheet and the sheet | seat base material did not peel favorably, but the primary composite material sheet was torn.
And it measured like Example 1. The results are shown in Table 1.

From Table 1, particles of a composite material containing a resin and an inorganic material and having a blocking resistance of 0% or more and 80% or less have a peeling force of at least one sheet substrate of 0.03 N / cm or more and 4.0 N / In Examples 1 to 5, which are sandwiched between sheet bases of less than cm and subjected to primary pressure, Comparative Examples 1 to 2 and Comparative Example 5 in which two sheet bases are outside the above predetermined range, and the blocking resistance is predetermined. It can be seen that the thickened primary composite material sheet can be satisfactorily formed as compared with Comparative Example 4 which is out of the range.
On the other hand, in Comparative Example 3 which can be formed into a primary composite material sheet but has a small thickness, a laminate is formed with a number of stacks that is about three times higher than in Examples 1 to 5 in which the primary composite material sheet is thickened. It can be seen that it takes time to manufacture the composite material sheet.

According to the present invention, a thickened primary composite material sheet can be formed. For example, even when a composite material sheet is manufactured using a laminate of primary composite material sheets, the composite material sheet is efficiently manufactured. It is possible to provide a method for pressing the particles of the composite material.
Moreover, according to this invention, the manufacturing method of a composite material sheet which can manufacture a composite material sheet efficiently can be provided.

Claims (8)

A pressurizing method in which primary pressure is applied in a state where particles of a composite material including a resin and an inorganic material are sandwiched between two sheet base materials,
The blocking resistance of the composite material particles is 0% or more and 80% or less,
The pressurizing method in which the peeling force of at least one of the two sheet base materials is 0.03 N / cm or more and less than 4.0 N / cm.   The pressurizing method according to claim 1, wherein a peeling force of at least one of the two sheet base materials is 0.30 N / cm or more and 3.00 N / cm or less.   The pressing method according to claim 1 or 2, wherein a thickness of the primary composite material sheet obtained by the primary pressing is 1.0 mm or more. Obtaining a primary composite sheet according to the pressurizing method according to any one of claims 1 to 3,
Laminating a plurality of the primary composite sheets in the thickness direction, or folding or winding the primary composite sheets to obtain a laminate;
Slicing the laminated body at an angle of 45 ° or less with respect to the laminating direction to obtain a composite material sheet. Further comprising the step of obtaining a compressed laminate by compressing the laminate by secondary pressure in the lamination direction,
The method for producing a composite material sheet according to claim 4, wherein, in the step of obtaining the composite material sheet, the composite material sheet is obtained by slicing the compressed laminate at an angle of 45 ° or less with respect to the lamination direction.   The method for manufacturing a composite material sheet according to claim 5, wherein a reduction rate of the laminate height due to the secondary pressurization is 1% or more and 30% or less.   The manufacturing method of a composite material sheet | seat further including the process of compressing the composite material sheet obtained according to the manufacturing method as described in any one of Claims 4-6 by carrying out the tertiary press in the thickness direction.   The method for producing a composite material sheet according to claim 7, wherein a reduction rate of the sheet thickness due to the third pressurization is 1% or more and 40% or less.