JP7003613B2 - Resin sheet manufacturing method - Google Patents

Description

The present invention relates to a method for producing a resin sheet, and more particularly to a method for producing a resin sheet containing a resin and a filler.

Conventionally, a resin sheet containing a resin and a filler has been used for various purposes. Specifically, for example, a resin sheet containing a resin and a heat conductive filler as a filler is used to dissipate heat from a heating element (for example, an electronic component) to a heat sink (for example, a metal heat sink, a heat sink, or a heat dissipation plate). It is used as a heat conductive sheet that is sandwiched between a heating element and a heat sink in order to efficiently transfer heat to fins and the like.

Further, as a method for producing a resin sheet containing a resin and a filler, a method of slicing a resin block containing the resin and the filler with a single-edged cutting blade is used (see, for example, Patent Document 1).

Then, in Patent Document 1, for example, by roughening or coating the surface of the cutting blade, the frictional resistance generated between the surface of the cutting blade and the surface of the sliced piece (resin sheet) when slicing the resin block is reduced. The obtained resin sheet prevents waviness.

Japanese Unexamined Patent Publication No. 2002-086391

However, there is room for improvement in the conventional method for producing a resin sheet in terms of improving the uniformity of the thickness of the obtained resin sheet.

Therefore, an object of the present invention is to provide a method for producing a resin sheet having excellent thickness uniformity.

The present inventor has made diligent studies for the purpose of solving the above problems. As a result, in the conventional method for manufacturing a resin sheet, the present inventor has a thickness of the resin sheet on the end side of the slice rather than the start end side of the slice because the cutting blade used for slicing the resin block presses the resin block at the time of slicing. It was newly found that the resin becomes thinner. Then, the present inventor further studied the shape of the cutting blade and the posture of the cutting blade with respect to the resin block at the time of slicing based on the above new findings, and completed the present invention.

That is, the present invention aims to advantageously solve the above problems, and the method for producing a resin sheet of the present invention is to slice a resin block containing a resin and a filler with a double-edged cutting blade. A method for manufacturing a resin sheet, which comprises a step of obtaining a resin sheet made of sliced pieces and a resin block balance, wherein the cutting blade includes a first blade surface, a second blade surface, and the first blade surface and the second blade surface. It has a blade portion having a blade edge composed of an intersection angle portion with and a flat plate-shaped flat portion located on the side opposite to the blade edge side of the blade portion, and in the step, the resin block remaining portion of the flat portion. Slice the resin block so that the angle between the surface on the side and the sliced surface of the rest of the resin block is more than 0 °, assuming that the surface is located on one side of the slice with respect to the sliced surface. It is characterized by. In this way, if the resin block is sliced so that the angle between the surface of the flat part on the remaining side of the resin block and the sliced surface of the remaining part of the resin block exceeds 0 °, a resin sheet having excellent thickness uniformity can be obtained. Obtainable.

Here, in the method for manufacturing a resin sheet of the present invention, in the step, the first blade surface is located on the remaining side of the resin block with respect to the second blade surface, and the first blade surface and the resin block are located. It is preferable to slice the resin block so that the remaining slice surface is parallel to the slice surface. If the resin block is sliced so that the first blade surface located on the remaining side of the resin block and the sliced surface of the remaining resin block are parallel to each other, the uniformity of the thickness of the obtained resin sheet can be further improved. ..

Further, in the method for producing a resin sheet of the present invention, the resin block is a laminate of sheets containing a resin and a filler, and in the step, the laminate can be sliced in the stacking direction with the cutting blade. preferable. When the above-mentioned cutting blade is used in the above-mentioned posture, a resin having excellent thickness uniformity is excellent even when a resin sheet is manufactured by slicing a laminate of sheets containing a resin and a filler in the lamination direction. You can get a sheet.
In the present invention, "slicing in the stacking direction" means slicing in the stacking direction, and "slicing in the stacking direction" means slicing in the direction along the stacking direction and the stacking direction. Includes slicing in a direction with an angle of 5 ° or less.

Further, in the method for producing a resin sheet of the present invention, the tensile elongation of the sheet is preferably 50% or less. When the tensile elongation of the sheets constituting the laminated body is not more than the above upper limit value, the laminated body can be easily sliced.
In the present invention, "tensile elongation" can be measured at a temperature of 25 ° C. using the method described in Examples.

In the method for producing a resin sheet of the present invention, it is preferable that the maximum thickness of the blade portion is 3 mm or more. When the maximum thickness of the blade portion is 3 mm or more, the strength and ease of manufacture of the cutting blade can be sufficiently ensured.
Further, in the method for producing a resin sheet of the present invention, the length of the first blade surface is preferably 70 mm or less. When the length of the first blade surface is 70 mm or less, the uniformity of the thickness of the obtained resin sheet can be further improved.

According to the present invention, it is possible to produce a resin sheet having excellent thickness uniformity.

(A) to (c) are explanatory views showing the process of manufacturing a resin sheet using an example of the method of manufacturing a resin sheet according to the present invention. It is an enlarged figure which shows the shape of an example of a cutting blade used for slicing a resin block. (A) to (c) are diagrams showing the shape of the cutting blade used when slicing the resin block and the posture with respect to the resin block in the comparative example.

Hereinafter, embodiments of the present invention will be described in detail.
In each figure, those with the same reference numerals indicate the same components.

(Manufacturing method of resin sheet)
The method for producing a resin sheet of the present invention is used when producing a resin sheet containing a resin and a filler and optionally further containing an additive. The resin sheet produced by using the method for producing a resin sheet of the present invention is not particularly limited, and can be used as, for example, a heat conductive sheet, a conductive sheet, an electromagnetic wave absorbing sheet, or the like.

Here, the method for producing a resin sheet of the present invention includes a step of slicing a resin block containing a resin and a filler with a double-edged cutting blade to obtain a resin sheet made of sliced pieces and the rest of the resin block. Specifically, the method for producing a resin sheet of the present invention is not particularly limited, and for example, as shown in FIGS. 1A to 1B, the double-edged cutting blade 20 is sliced in the slicing direction (illustration example). Then, the resin block 10 containing the resin and the filler is sliced by the cutting blade 20 by moving it downward) to obtain a resin sheet 30 made of sliced pieces of the resin block 10 and a resin block balance 40, and then FIG. As shown in (c), the cutting blade 20 is moved to the upper retreat position in the illustrated example, and the resin block remaining portion 40 is moved to the cutting position side (left side in the illustrated example) by the desired thickness of the resin sheet. By repeating the operation of slicing and slicing again, a plurality of resin sheets 30 are obtained from the resin block 10.
In FIG. 1C, the remaining portion 40 of the resin block is moved by the thickness of the desired resin sheet, but in the method for producing the resin sheet of the present invention, the cutting blade 20 is moved by the thickness of the desired resin sheet. It may be moved only to the resin block remaining portion 40 side (right side in the illustrated example), or both the cutting blade 20 and the resin block remaining portion 40 may be moved.

The method for producing a resin sheet of the present invention is characterized in that a predetermined cutting blade is used in a predetermined posture as a double-edged cutting blade for slicing a resin block.

<Resin block>
The resin block used as the material of the resin sheet contains a resin and a filler, and optionally further contains an additive.

[resin]
Here, as the resin, any resin depending on the use of the resin sheet can be used. Specifically, as the resin, at least one of a liquid resin under normal temperature and pressure and a solid resin under normal temperature and pressure can be used. In the present specification, "normal temperature" means 23 ° C., and "normal pressure" means 1 atm (absolute pressure).

Examples of the resin that is liquid under normal temperature and pressure include a thermoplastic resin that is liquid under normal temperature and pressure and a thermosetting resin that is liquid under normal temperature and pressure.
Examples of the thermoplastic resin that is liquid under normal temperature and pressure include acrylic resin, epoxy resin, silicon resin, and fluororesin.
Examples of the thermosetting resin that is liquid under normal temperature and pressure include natural rubber; butadiene rubber; isoprene rubber; nitrile rubber; hydride nitrile rubber; chloroprene rubber; ethylene propylene rubber; chlorinated polyethylene; chlorosulfonated polyethylene; Butyl rubber; halogenated butyl rubber; 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 Type-modified polyphenylene ether; and the like.

Examples of the resin that is solid under normal temperature and pressure include a solid thermoplastic resin under normal temperature and pressure and a solid thermosetting resin under normal temperature and pressure.
Examples of the solid thermoplastic resin under normal temperature and 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 resin such as the ester; Silicon resin; Fluorine resin; Polyethylene; Polypropylene; Ethylene-propylene copolymer; Polymethylpentene; Polyvinyl chloride; Polyvinyl chloride; Polyacetic acid vinyl; Ethylene-vinyl acetate copolymer; Polyvinyl alcohol Polyacetal; polyethylene terephthalate; polybutylene terephthalate; polyethylene naphthalate; polystyrene; polyacrylonitrile; styrene-acrylonitrile copolymer; acrylonitrile-butadiene-styrene copolymer (ABS resin); styrene-butadiene block copolymer or hydrogenation thereof Material; styrene-isoprene block copolymer or hydrogenated product thereof; polyphenylene ether; modified polyphenylene ether; aliphatic polyamides; aromatic polyamides; polyamideimide; polycarbonate; polyphenylene sulfide; polysulfone; polyether sulfone; polyether nitrile ; Polyether ketone; Polyketone; Polyurethane; Liquid polymer; Ionomer;
Examples of the thermosetting resin that is solid under normal temperature and pressure include natural rubber; butadiene rubber; isoprene rubber; nitrile rubber; hydride nitrile rubber; chloroprene rubber; ethylene propylene rubber; chlorinated polyethylene; chlorosulfonated polyethylene; Butyl rubber; halogenated butyl rubber; 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 Type-modified polyphenylene ether; and the like.

The above-mentioned resins may be used alone or in combination of two or more.

[Filler]
As the filler, any filler depending on the use of the resin sheet can be used. Specifically, the filler is not particularly limited, and for example, a heat conductive filler that imparts thermal conductivity to the resin sheet, a reinforcing filler that enhances the strength of the resin sheet, and conductivity to the resin sheet. At least one filler selected from the group consisting of conductive fillers that impart properties can be used. More specifically, when the resin sheet is used as the heat conductive sheet, a heat conductive filler can be used as the filler, and when the resin sheet is used as the conductive sheet or the electromagnetic wave absorbing sheet, the filler can be used. A conductive filler can be used.
The amount of the filler to be blended in the resin block is not particularly limited, and may be, for example, 5 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the resin described above.

Here, the thermally conductive filler is not particularly limited, and for example, alumina particles, zinc oxide particles, boron nitride particles, aluminum nitride particles, silicon nitride particles, silicon carbide particles, magnesium oxide particles and particulate carbon. Examples thereof include particulate materials such as materials, and fibrous materials such as carbon nanotubes, vapor-grown carbon fibers, carbon fibers obtained by carbonizing organic fibers, and cut pieces thereof. Among them, as the heat conductive filler, boron nitride particles; particulate carbon materials such as artificial graphite, scaly graphite, flaky graphite, natural graphite, acid-treated graphite, expandable graphite, expanded graphite and carbon black; and , Carbon nanotubes (hereinafter, may be referred to as “CNT”) and other fibrous carbon nanomaterials; it is preferable to use at least one selected from the group consisting of.
As the heat conductive filler, one type may be used alone, or two or more types may be used in combination.

The reinforcing filler is not particularly limited, and is, for example, a particulate material such as carbon black, mica, silica particles, calcium carbonate particles, aluminum hydroxide particles, aluminum oxide particles and titanium oxide particles, and Examples thereof include fibrous materials such as CNTs, vapor-grown carbon fibers, carbon fibers obtained by carbonizing organic fibers, and cut products thereof. Among them, as the reinforcing filler, it is preferable to use at least one selected from the group consisting of carbon black, silica particles and CNTs.
As the reinforcing filler, one type may be used alone, or two or more types may be used in combination.

Further, the conductive filler is not particularly limited, and for example, a particulate material such as carbon black, graphite and metal particles, and carbon obtained by carbonizing CNT, gas phase growth carbon fiber and organic fiber. Fibrous materials such as fibers and their cuts can be mentioned. Among them, as the conductive filler, it is preferable to use at least one selected from the group consisting of carbon black, metal particles and CNTs.
As the conductive filler, one type may be used alone, or two or more types may be used in combination.

The volume average particle size of the above-mentioned particulate material that can be used as a filler is preferably 50 μm or more and 300 μm or less, and more preferably 150 μm or more and 300 μm or less.
The aspect ratio (major axis / minor axis) of the particulate material is preferably 1 or more and 10 or less, and more preferably 1 or more and 5 or less.
The "aspect ratio of the particulate material" is the maximum diameter (major diameter) and the particle diameter in the direction orthogonal to the maximum diameter (major diameter) for any 50 particulate materials using an SEM (scanning electron microscope). It can be obtained by measuring the minor axis) and calculating the average value of the ratio of the major axis to the minor axis (major axis / minor axis).

Further, the aspect ratio (major axis / minor axis) of the above-mentioned fibrous material that can be used as a filler is preferably more than 10.
The "aspect ratio of the fibrous material" is the maximum diameter (major diameter) of 100 fibrous materials randomly selected using a TEM (transmission electron microscope) and the outer diameter in the direction orthogonal to the maximum diameter. It can be obtained by measuring (minor diameter) and calculating the average value of the ratio of major axis to minor axis (major axis / minor axis).

[Additive]
The additives that can be arbitrarily blended in the resin block are not particularly limited, and examples thereof include flame retardants, plasticizers, toughness improving agents, moisture absorbing agents, adhesive strength improving agents, wettability improving agents, ion trapping agents and the like. Can be mentioned.

[Shape and structure of resin block]
The shape of the resin block is not particularly limited, and can be a shape that can obtain a resin sheet having a desired shape when sliced. Specifically, for example, when manufacturing a rectangular resin sheet, the shape of the resin block is preferably a rectangular parallelepiped.

Further, the structure of the resin block is not particularly limited, and a resin composition containing a resin and a filler and optionally further containing an additive can be formed into a desired shape using a known molding device such as a mold. A sheet obtained by molding a resin composition containing a resin and a filler and optionally further containing an additive into a sheet may be laminated, folded or rolled. It may be a structure made by turning.
In a laminated body formed by laminating sheets, the adhesive force between the surfaces of the sheets is usually sufficiently obtained by the pressure at the time of laminating the sheets. However, if the adhesive strength is insufficient or if it is necessary to sufficiently suppress delamination of the laminated body, the sheet may be laminated with the surface of the sheet slightly dissolved with a solvent, or the surface of the sheet may be laminated. The laminating may be performed with the adhesive applied to the sheet or with the adhesive layer provided on the surface of the sheet, or the laminated body in which the sheets are laminated may be further pressed in the laminating direction.

Above all, the structure of the resin block is formed into a sheet by pressurizing a resin composition containing a resin and a filler and optionally further containing an additive, such as the resin block 10 shown in FIG. After obtaining a sheet 11 containing a resin, a filler, and an arbitrary additive, a structure in which a plurality of the obtained sheets 11 are laminated in the thickness direction, or the obtained sheet 11 is folded or rolled up. It is preferable that the structure is made by turning. In a sheet formed by pressurizing the resin composition into a sheet, the filler is oriented in the in-plane direction of the sheet. This is because it is possible to obtain a resin sheet having anisotropy in properties such as thermal conductivity and conductivity. Specifically, for example, in a sheet formed by pressurizing a resin composition containing a heat conductive filler as a filler into a sheet, the heat conductive filler is oriented in the in-plane direction and is in the in-plane direction. Thermal conductivity is improved. Therefore, if the laminated body of the sheet is sliced in the laminating direction of the laminated body (vertical direction in the example shown in FIGS. 1A to 1C), a resin sheet (heat conductive sheet) having excellent thermal conductivity in the thickness direction is obtained. ) Can be obtained.
Here, in the method for manufacturing a resin sheet of the present invention, since a predetermined cutting blade is used for slicing the resin block in a predetermined posture, the laminated body of the sheet containing the resin and the filler is sliced in the laminating direction to form a resin. Even when the sheet is manufactured, it is possible to obtain a resin sheet having excellent thickness uniformity.

The above-mentioned sheet used for forming the resin block made of a laminated body preferably has a tensile elongation of 50% or less, more preferably 30% or less, still more preferably 20% or less. .. This is because if the tensile elongation of the sheets constituting the laminated body is not more than the above upper limit value, the laminated body can be easily sliced. The tensile elongation of the sheet is usually 1% or more.

<Cut blade>
The cutting blade used for slicing the resin block described above includes a blade portion having a first blade surface, a second blade surface, and a blade edge including an intersection angle portion of the first blade surface and the second blade surface, and a blade. It is a double-edged cutting blade having a flat plate-shaped flat portion located on the side opposite to the cutting edge side of the portion.

Specifically, for example, as shown in FIG. 2, the cutting blade 20 that can be used in the method for manufacturing a resin sheet of the present invention has a blade portion 21 having a cutting edge 25 and an extending direction of the cutting blade 20 (in FIG. 2). It is provided with a flat portion 22 located on the side opposite to the blade edge 25 side (upper side in FIG. 2) of the blade portion 21 (in the vertical direction). The cutting blade 20 is a symmetrical double-edged blade in which the shape of the blade portion 21 is a plane-symmetrical shape having a virtual surface extending along the extending direction of the cutting blade 20 through the cutting edge 25 as a symmetrical surface.
The cutting blade used in the method for manufacturing the resin sheet of the present invention may be an asymmetric double-edged blade as long as it is a double-edged blade, but from the viewpoint of ease of manufacturing, a symmetrical double-edged blade is preferable.

The blade portion 21 of the cutting blade 20 is a cutting edge composed of a first blade surface 23 and a second blade surface 24 intersecting at an angle (blade angle) 2θ, and an intersecting angle portion between the first blade surface 23 and the second blade surface 24. It has 25 and. The cutting edge 25 extends in a direction orthogonal to the paper surface of FIG. 2 with a length equal to or larger than the width of the sliced resin block 10 (dimensions in the direction orthogonal to the paper surface in the example shown in FIG. 1).

Here, the blade angle 2θ is preferably 10 ° or more, more preferably 15 ° or more, more preferably 40 ° or less, and even more preferably 25 ° or less. When the blade angle 2θ is equal to or higher than the above lower limit value, the cutting blade 20 can be easily manufactured and the strength of the cutting blade 20 can be sufficiently secured. Further, when the blade angle 2θ is not more than the above upper limit value, the uniformity of the thickness of the obtained resin sheet can be improved.

From the viewpoint of sufficiently ensuring the strength and manufacturability of the cutting blade 20, the maximum thickness D of the blade portion 21 is preferably 1 mm or more, and more preferably 3 mm or more. Further, from the viewpoint of improving the uniformity of the thickness of the obtained resin sheet and from the viewpoint of suppressing the increase in the weight of the cutting blade to improve the handleability of the cutting blade, the maximum thickness D of the blade portion 21 is 15 mm. It is preferably less than or equal to, more preferably 7 mm or less, still more preferably 5 mm or less.

Further, the flat portion 22 of the cutting blade 20 has a flat plate shape, and has a first plane 26 intersecting with an edge of the first blade surface 23 opposite to the cutting edge 25 side (upper side in FIG. 2). It is provided with a second flat surface 27 that intersects the edge of the two-blade surface 24 opposite to the blade edge 25 side.

<Slice>
In the method for producing a resin sheet of the present invention, in the resin block slice using the cutting blade, the angle between the surface of the flat portion on the resin block remaining side and the sliced surface of the resin block remaining is the surface of the flat portion. It is necessary to make the case where is located on the slice piece (resin sheet) side of the slice surface as positive and to be more than 0 °.

Specifically, for example, as shown in FIGS. 1A to 1C, the slice of the resin block 10 using the cutting blade 20 is the surface of the flat portion 22 on the resin block remaining 40 side (right side in FIG. 1). The angle α between the first plane 26 and the slice surface 41 of the resin block remaining portion 40 is positive when the first plane 26 is located on the resin sheet 30 side (left side in FIG. 1) with respect to the slice surface 41. , It is necessary to do so so that it exceeds 0 °. In this way, if the posture of the cutting blade 20 when slicing the resin block 10 is set so that the angle α exceeds 0 °, the first plane 26 comes into contact with the resin block remaining portion 40 during slicing. In the example shown in FIGS. 1 (a) to 1 (c), it is possible to prevent the resin block remaining portion 40 from being pressed to the right side. Therefore, due to the pressing of the resin block remaining portion 40 by the first plane 26, the slice ending side (lower side in the example shown in FIGS. 1A to 1C) is the starting end side of the slice (FIGS. 1A to 1C). In the example shown in the above example, the thickness of the resin sheet 30 can be prevented from becoming thinner than that of the upper side), and the resin sheet 30 having excellent thickness uniformity can be obtained.

The angle α is usually less than 90 ° -2θ, preferably 5 ° or more, more preferably 7.5 ° or more, preferably 20 ° or less, and 12.5 °. The following is more preferable. When the angle α is within the above range, the resin block 10 can be sliced well and the uniformity of the thickness of the obtained resin sheet 30 can be improved.

Here, when the resin block 10 is sliced by the cutting blade 20 in a posture in which the first blade surface 23 is located closer to the resin block remaining portion 40 than the second blade surface 24 as shown in FIGS. 1 (a) to 1 (c). From the viewpoint of slicing the resin block 10 well and further improving the uniformity of the thickness of the obtained resin sheet 30, the posture of the cutting blade 20 is such that the first blade surface 23 is the slice surface 41 of the resin block remaining portion 40. It is preferable that the posture is parallel to the above. That is, when the resin block 10 made of the laminated body of the sheets 11 is sliced in the laminating direction (vertical direction in the example shown in FIGS. 1A to 1C), the posture of the cutting blade 20 is such that the first blade surface 23 is used. It is preferable to have a posture extending along the stacking direction (slice direction).
When a symmetrical double-edged blade having a blade angle of 2θ is used as the cutting blade 20, if the posture of the cutting blade 20 is set so that the first blade surface 23 is parallel to the slice surface 41 of the resin block remaining portion 40, the first flat surface is used. The magnitude of the angle α formed by 26 and the slice surface 41 is θ.

When the direction of the first blade surface 23 at the time of slicing is parallel to the slice surface 41 of the resin block remaining portion 40, the length L of the first blade surface 23 is preferably 3 mm or more, preferably 5 mm. It is more preferably 70 mm or less, more preferably 40 mm or less, further preferably 20 mm or less, and particularly preferably 15 mm or less. When the length L is at least the above lower limit value, the cutting blade 20 can be easily manufactured. Further, when the length L is equal to or less than the above upper limit value, the thickness of the obtained resin sheet is obtained by suppressing an increase in the area of the first blade surface 23 in contact with the slice surface 41 of the resin block remaining portion 40 at the time of slicing. Uniformity can be improved.
In the cutting blade 20, the length L of the first blade surface 23 is usually shorter than the length of the first plane 26.

Here, in the method for producing a resin sheet of the present invention, slicing of the resin block using the above-mentioned cutting blade is not particularly limited, and it is preferable to perform the slicing while applying pressure to the resin block. It is more preferable to carry out the operation while applying a pressure of 1 MPa or more and 1.0 MPa or less.

Further, from the viewpoint of easily slicing the resin block, the temperature of the resin block at the time of slicing is preferably −20 ° C. or higher and 30 ° C. or lower.

Further, the slicing speed of the resin block is not particularly limited, and is preferably 50 mm / sec or more, more preferably 100 mm / sec or more, and further preferably 200 mm / sec or more. When the slicing speed is set to the above lower limit value or more, the productivity of the resin sheet can be increased, and the uniformity of the thickness of the obtained resin sheet can be further improved.
The slicing speed of the resin block is usually 600 mm / sec or less. When the slicing speed is set to the above upper limit or less, the movement of the cutting blade can be easily controlled and the resin block can be prevented from being pushed by the impact at the time of slicing.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In Examples and Comparative Examples, the ease of manufacturing the cutting blade, the tensile elongation of the sheet, and the uniformity of the thickness of the resin sheet were measured and evaluated using the following methods, respectively.

<Easy to manufacture cutting blades>
The ease of preparing a cutting blade by polishing the blade portion of the cutting blade using a diamond wheel is shown by the following criteria. If the thickness of the blade portion is thin, the rigidity is insufficient, and it takes time because it is necessary to reduce the rotation speed of the diamond wheel and polish slowly so that the cutting blade does not bend during polishing.
◯: Time required for polishing the blade is 5 hours or less Δ: Time required for polishing the blade is more than 5 hours and 10 hours or less ×: Time required for polishing the blade is more than 10 hours <Tension elongation>
The prepared sheet was punched and molded with dumbbell No. 2 in accordance with JIS K6251 to prepare a sample piece. Then, using a tensile tester (manufactured by Shimadzu Corporation, trade name "AG-IS20kN"), pinch 1 cm from both ends of the sample piece, and at a temperature of 25 ° C, perpendicular to the normal line coming out of the surface of the sample piece. The sample was pulled at a tensile speed of 500 mm / min in the above direction, and the elongation (%) between the marked lines was measured.
<Thickness uniformity>
The uniformity of the thickness of the resin sheet was evaluated using a film thickness meter (manufactured by Mitutoyo, product name "Digimatic Indicator ID-C112XBS").
Specifically, the thickness of the produced substantially square resin sheet was measured with a film thickness meter at a total of 9 points including the center point, the four corners, and the center points of each of the four sides, and the maximum value of the measured thickness was used. The difference from the minimum value was calculated.
The smaller the difference value, the smaller the distribution of the thickness in the resin sheet, and the better the uniformity of the thickness.

(Example 1)
<Preparation of resin block>
400 mg of carbon nanotubes (manufactured by Nippon Zeon Corporation, specific surface area: 600 m ² / g) were weighed, mixed in 2 L of methyl ethyl ketone as a solvent, and stirred with a homogenizer for 2 minutes to obtain a crude dispersion. Next, using a wet jet mill (manufactured by Tsunemitsu Co., Ltd., product name "JN-20"), the obtained crude dispersion was passed through a 0.5 mm flow path of the wet jet mill for two cycles at a pressure of 100 MPa. The carbon nanotubes were dispersed in methyl ethyl ketone. Then, a dispersion liquid having a solid content concentration of 0.20% by mass was obtained.
Then, the dispersion obtained above was filtered under reduced pressure using Kiriyama filter paper (No. 5A) to obtain an easily dispersible aggregate of sheet-shaped carbon nanotubes.
Then, 70 parts of a liquid thermoplastic fluororesin (manufactured by Daikin Industries, Ltd., trade name "Daiel G-101") under normal temperature and pressure, and a solid thermoplastic fluororesin (manufactured by 3M Japan Co., Ltd.) under normal temperature and pressure. Product name "Dynion FC2211", Mooney viscosity (ML _{1 + 4} , 100 ° C): 27) and expanded fluoropolymer as a thermally conductive filler (manufactured by Ito Graphite Industry Co., Ltd., product name "EC50", volume average 50 parts (particle size: 250 μm) and 0.5 part of the easily dispersible aggregate of carbon nanotubes were stirred and mixed at a temperature of 150 ° C. for 20 minutes using a pressurized kneader (manufactured by Nippon Spindle). Next, the obtained mixture was put into a crusher and crushed for 10 seconds to obtain a resin composition.
Next, 50 g of the obtained resin composition was sandwiched between sandblasted PET films (protective films) having a thickness of 50 μm, a roll gap of 550 μm, a roll temperature of 50 ° C., a roll linear pressure of 50 kg / cm, and a roll speed of 1 m / min. Roll molding (primary pressurization) was performed under the conditions to obtain a sheet having a thickness of 0.5 mm. Then, the tensile elongation of the sheet was measured. The results are shown in Table 1.
Subsequently, the obtained sheet was cut into a length of 150 mm × width of 150 mm × thickness of 0.5 mm, 300 sheets were laminated in the thickness direction of the sheet, and further pressed in the stacking direction at a temperature of 120 ° C. and a pressure of 0.1 MPa for 3 minutes. By (secondary pressurization), a resin block made of a laminated body having a height of about 150 mm was obtained.
<Manufacturing of resin sheet>
Subsequently, the entire upper surface of the obtained resin block was pressed with a metal plate, leaving 1 cm required for slicing, and a pressure of 0.1 MPa was applied from above to fix the laminate. The sides and back of the laminate were not fixed.
Next, in the press portion of the servo press machine (manufactured by Discharge Precision Machining Laboratory), a cutting blade (double-edged, blade angle 2θ: 20 °, length L of the first blade surface) having the shape shown in FIG. : 20.0 mm, maximum blade thickness D: 3.5 mm, material: super steel, rockwell hardness: 91.5, blade surface silicon processing: none, total length: 200 mm, first plane length: 27 mm) The resin block was sliced in the stacking direction of the sheets under the conditions of a slicing speed of 200 mm / sec and a slice width of 150 μm to obtain a resin sheet (heat conductive sheet) having a substantially square plan view. As for the posture of the cutting blade at the time of slicing, the angle α between the first plane and the sliced surface of the remaining resin block is 10 °, and the extending direction of the first blade surface is parallel to the sliced surface of the remaining resin block. The posture was set to be in the direction.
Then, the uniformity of the thickness of the obtained resin sheet was evaluated. The results are shown in Table 1.

(Example 2)
As the cutting blade, a cutting blade having the shape shown in FIG. 2 prepared in advance (double-edged, blade angle 2θ: 10 °, first blade surface length L: 10.0 mm, maximum blade thickness D: 1. 7 mm, material: super steel, rockwell hardness: 91.5, blade surface silicon processing: none, total length: 200 mm, first plane length: 27 mm), the posture of the cutting blade at the time of slicing, angle The resin block and the resin sheet were manufactured in the same manner as in Example 1 except that the α was 5 ° and the extending direction of the first blade surface was in a direction parallel to the slice surface of the rest of the resin block. Then, measurement and evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
As the cutting blade, a cutting blade having the shape shown in FIG. 2 prepared in advance (double-edged, blade angle 2θ: 40 °, first blade surface length L: 20.0 mm, maximum blade thickness D: 6. 8 mm, material: super steel, rockwell hardness: 91.5, blade surface silicon processing: none, total length: 200 mm, first plane length: 27 mm), the posture of the cutting blade at the time of slicing, angle A resin block and a resin sheet were manufactured in the same manner as in Example 1 except that α was set to 20 ° and the extending direction of the first blade surface was in a direction parallel to the slice surface of the rest of the resin block. Then, measurement and evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 4)
As the cutting blade, a cutting blade having the shape shown in FIG. 2 prepared in advance (double-edged, blade angle 2θ: 20 °, first blade surface length L: 40.0 mm, maximum blade thickness D: 7. Resin block in the same manner as in Example 1 except that 0 mm, material: super steel, rockwell hardness: 91.5, blade surface silicon processing: none, total length: 200 mm, first plane length: 27 mm) was used. And manufactured a resin sheet. Then, measurement and evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
As shown in FIG. 3A, the posture of the cutting blade at the time of slicing is set so that the angle α is 0 ° and the extending direction of the first plane is parallel to the slice plane of the rest of the resin block. A resin block was produced in the same manner as in Example 1 except for the above, and an attempt was made to produce a resin sheet.
However, the maximum thickness of the resin sheet became about 300 μm, and it was not possible to obtain a resin sheet having a desired thickness (150 μm).

(Comparative Example 2)
As a cutting blade, a cutting blade having the shape shown in FIG. 3 (b) (single blade, made by Finetech, blade angle 2θ: 20 °, material: super steel, rockwell hardness: 91.5, blade surface silicon processing: none, The total length: 200 mm, the blade height: 27 mm, the maximum thickness of the blade D: 1 mm) was used, and the posture of the cutting blade at the time of slicing was the same as in Example 1 except that the posture was set so that the angle α was 20 °. A resin block was manufactured and an attempt was made to manufacture a resin sheet.
However, the resin block could not be sliced and the resin sheet could not be obtained.

(Comparative Example 3)
As a cutting blade, a cutting blade having the shape shown in FIG. 3 (c) (single blade, made by Finetech, blade angle 2θ: 20 °, material: super steel, rockwell hardness: 91.5, silicon processing of the blade surface: none, Using the total length: 200 mm, blade height: 27 mm, maximum blade thickness D: 1 mm), the posture of the cutting blade at the time of slicing is the posture in which the angle α becomes 0 ° as shown in FIG. 3 (c). A resin block and a resin sheet were produced in the same manner as in Example 1 except for the above. Then, measurement and evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

From Table 1, it can be seen that in Examples 1 to 3 in which the double-edged cutting blades are used in a predetermined posture, a resin sheet having excellent thickness uniformity can be obtained. On the other hand, from Comparative Example 1, it can be seen that even when a double-edged cutting blade is used, a resin sheet having a desired thickness cannot be obtained when the angle α is 0 °.
Further, from Table 1, in Comparative Example 2 using a single-edged cutting blade, the resin block could not be sliced well even if the angle α was set to 20 °, and the single-edged cutting was performed so that the angle α became 0 °. In Comparative Example 3 using a blade, it can be seen that a resin sheet having excellent thickness uniformity cannot be obtained.

According to the present invention, it is possible to produce a resin sheet having excellent thickness uniformity.

10 Resin block 11 Sheet 20 Cutting blade (double-edged)
21 Blade part 22 Flat part 23 First blade surface 24 Second blade surface 25 Cutting edge 26 First plane 27 Second plane 30 Resin sheet 40 Resin block balance 41 Slice surface 50 Cutting blade (single blade)

Claims (6)

Slice the resin block containing the resin and the filler with a double-edged cutting blade (except when slicing with a cutting blade whose cutting edge faces the slide surface supporting the end face of the resin block). A method for manufacturing a resin sheet, which comprises a step of obtaining a resin sheet made of pieces and a resin block balance.
The cutting blade has a blade portion having a blade edge composed of a first blade surface, a second blade surface, and an intersection angle portion between the first blade surface and the second blade surface, and is opposite to the blade edge side of the blade portion. It has a flat plate-like flat part located on the side,
In the step, the angle between the surface of the flat portion on the remaining side of the resin block and the slice surface of the remaining resin block is 0 °, assuming that the surface is located on one side of the slice with respect to the slice surface. A method for producing a resin sheet, which comprises slicing the resin block so as to be supernatural. In the step, the resin is located so that the first blade surface is located closer to the resin block remaining portion than the second blade surface, and the first blade surface and the slice surface of the resin block remaining portion are parallel to each other. The method for producing a resin sheet according to claim 1, wherein the block is sliced. The resin block is a laminated body of sheets containing a resin and a filler.
The method for producing a resin sheet according to claim 1 or 2, wherein in the step, the laminated body is sliced in the laminating direction with the cutting blade. The method for producing a resin sheet according to claim 3, wherein the tensile elongation of the sheet is 50% or less. The method for producing a resin sheet according to any one of claims 1 to 4, wherein the maximum thickness of the blade portion is 3 mm or more. The method for producing a resin sheet according to any one of claims 1 to 5, wherein the length of the first blade surface is 70 mm or less.

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