CN117285786A - Sheet, base material for printed board, and method for producing sheet - Google Patents

Sheet, base material for printed board, and method for producing sheet Download PDF

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Publication number
CN117285786A
CN117285786A CN202310725390.8A CN202310725390A CN117285786A CN 117285786 A CN117285786 A CN 117285786A CN 202310725390 A CN202310725390 A CN 202310725390A CN 117285786 A CN117285786 A CN 117285786A
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China
Prior art keywords
sheet
particle diameter
average particle
fluororesin
filler
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CN202310725390.8A
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Chinese (zh)
Inventor
渡边智和
铃木一平
佐藤亮太
本间智也
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Nichias Corp
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Nichias Corp
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Publication of CN117285786A publication Critical patent/CN117285786A/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0313—Organic insulating material
    • H05K1/0353—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement
    • H05K1/0373—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement containing additives, e.g. fillers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/16—Solid spheres
    • C08K7/18—Solid spheres inorganic

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Medicinal Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Laminated Bodies (AREA)

Abstract

The present invention relates to a sheet comprising the following components (A) and (B), wherein the average particle diameter of the (B) fluororesin is 20% or less relative to the prescribed thickness of the sheet, and the elongation at break of the sheet exceeds 150%.

Description

Sheet, base material for printed board, and method for producing sheet
Technical Field
The present invention relates to a sheet, a base material for a printed board, and a method for manufacturing the sheet.
Background
The fluororesin is a synthetic resin having excellent heat resistance, electrical insulation, non-tackiness, and weather resistance, and is molded into a sheet form to form a fluororesin sheet, which is widely used in industrial fields such as chemical materials, electrical and electronic parts, semiconductors, automobiles, and the like.
In some cases, various properties such as electrical properties and thermal properties of the fluororesin sheet are insufficient in relation to these uses, and thus, the fluororesin and the filler are mixed and used for the purpose of improving these properties (patent documents 1 to 4).
As an application example of a synthetic resin such as a fluororesin, there is known: for example, the release sheet is used as a release sheet by utilizing the characteristics of non-tackiness and excellent releasability. However, since a general-purpose fluororesin (for example, polytetrafluoroethylene (hereinafter, referred to as PTFE)) has a relatively large thermal expansion coefficient, the use of the fluororesin as a release sheet may cause a problem such as a poor thermal stability and a size difference from a release object during heating. Therefore, a filler (filler) is mixed in a sheet for the purpose of suppressing thermal expansion of a fluororesin sheet such as PTFE. For example, patent document 2 discloses that the thermal expansion coefficient of a sheet obtained after molding is reduced by using a PTFE composition in which a PTFE resin and a ceramic powder are mixed in a predetermined manner.
On the other hand, in a fluororesin sheet in which a filler is mixed with a fluororesin, if the film thickness of the sheet is small, through holes (pinholes) tend to be formed easily, and the tensile properties as a sheet tend to be lowered easily.
Prior art literature:
patent document 1: international publication No. 2019/031071
Patent document 2: japanese patent application laid-open No. 2022-510017
Patent document 3: japanese patent No. 2557248
Patent document 4: japanese patent laid-open No. 10-17838
Disclosure of Invention
In order to solve the above problems, the present inventors have attempted to use a filler having a smaller particle diameter as a filler to be mixed into a fluororesin sheet, to suppress the generation of through holes (pinholes) and to suppress the reduction of tensile properties, but have failed to solve these problems.
The purpose of the present invention is to provide a sheet that has excellent thermal stability (low thermal expansion) and excellent tensile properties.
According to the present invention, the following sheet and the like are provided.
1. A sheet comprising the following components (A) and (B),
(A) A fluororesin, which is composed of a fluorine-containing resin,
(B) A filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet,
the elongation at break of the sheet is over 150%.
2. The sheet according to 1, wherein the sheet has a predetermined thickness of 25 to 300. Mu.m.
3. The sheet according to 1 or 2, wherein the filler has an average particle diameter of 0.1 to 10 μm.
4. The sheet according to any one of 1 to 3, wherein the filler is mixed in a proportion of 20 to 50% by volume.
5. The sheet according to any one of claims 1 to 4, wherein the fluororesin is Polytetrafluoroethylene (PTFE) or modified PTFE.
6. The sheet according to any one of claims 1 to 5, wherein the filler is at least one selected from the group consisting of alumina, titania, silica, barium sulfate, silicon carbide, boron nitride, silicon nitride, glass fibers, glass beads, and mica.
7. The sheet according to any one of claims 1 to 6, wherein the sheet has a thermal expansion rate of less than 100ppm/°c.
8. The sheet according to any one of claims 1 to 7, wherein the number of through holes having a diameter of 50 μm or more present in the sheet is per 100cm of the sheet 2 The surface area is 25 or less.
9. A substrate for a printed board, comprising the sheet according to any one of claims 1 to 8.
10. A method for producing a sheet, wherein,
comprising the following steps:
a step of preparing a raw material composition by mixing the following components (A') and (B);
forming the raw material composition into a cylindrical shape to form a molded body;
a step of firing the molded article; and
a step of cutting the surface of the molded body after firing to form a sheet,
a fluororesin having an average particle diameter of 50% or less relative to a predetermined thickness of the sheet, and a filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet.
11. The method for producing a sheet according to 10, wherein the sheet has a predetermined thickness of 25 to 300. Mu.m.
12. The method for producing a sheet according to 10 or 11, wherein the fluororesin particles have an average particle diameter of 0.1 to 10 μm.
13. The method for producing a sheet according to any one of claims 10 to 12, wherein the filler has an average particle diameter of 0.1 to 10 μm.
14. The method for producing a sheet according to any one of claims 10 to 13, wherein the filler is mixed in an amount of 20 to 50% by volume.
15. The method for producing a sheet according to any one of claims 10 to 14, wherein the step of producing the raw material composition comprises: and (B) a step of removing the solvent from a raw material-containing solution obtained by dispersing in the solvent a fluororesin having an average particle diameter of 50% or less relative to the predetermined thickness of the sheet and a filler having an average particle diameter of 20% or less relative to the predetermined thickness of the sheet.
16. The method for producing a sheet according to any one of claims 10 to 14, wherein the step of producing the raw material composition comprises a step of dry-mixing a fluororesin having an average particle diameter of 50% or less relative to a predetermined thickness of the sheet and a filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet.
17. A sheet obtained by the production method according to any one of claims 10 to 16.
According to the present invention, a sheet excellent in thermal stability (low thermal expansion) and excellent in tensile characteristics can be provided.
Drawings
Fig. 1 is a schematic diagram for explaining a method of producing a raw material composition in a conventional method of producing a sheet.
Fig. 2 is a schematic diagram for explaining a method of producing a raw material composition in a method of producing a sheet according to an embodiment of the present invention.
Fig. 3 is a view showing a cutting step of cutting the longitudinal outer peripheral surface of the molded article (blank) after firing to form a sheet shape.
Fig. 4 is a graph showing the results of elemental mapping analysis of the sheet of example 2.
Fig. 5 is a graph showing the result of the elemental mapping analysis of the sheet of comparative example 1.
Detailed Description
Hereinafter, a sheet and a method for manufacturing the sheet according to an embodiment of the present invention will be described. In the present specification, "x to y" means a numerical range of "x or more and y or less". In the case where there are a plurality of lower limit values such as "x or more" or a plurality of upper limit values such as "y or less", one technical matter can be arbitrarily selected from the upper limit values and the lower limit values and combined with each other.
[ sheet ]
The sheet according to one embodiment of the present invention is a sheet comprising the following components (A) and (B),
(A) A fluororesin, which is composed of a fluorine-containing resin,
(B) A filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet,
the elongation at break of the sheet is over 150%.
The sheet has one surface which is flat and the other surface which is back, regardless of the thickness, and is formed in a shape such as a belt or a flat plate, and includes, for example, a film and an adhesive tape.
The inventors found that: if a filler is mixed in a sheet containing a fluororesin, the thermal expansion rate of the sheet is suppressed to be low; on the other hand, if coarse particles having a particle diameter close to the thickness of the target sheet are present in the raw material composition, when a formed body made of the raw material composition is cut into a thin sheet shape of about 100 μm, through holes (pinholes) are formed in the sheet, and the sheet is likely to be broken by the through holes, and the tensile properties of the sheet are degraded.
In addition, the present inventors have found the following facts. That is, if there is a large difference between the particle size of the filler 51 in the raw material composition for producing a sheet and the particle size of the particles 50 of the fluororesin of the raw material (see fig. 1 (a)), as the mixing amount of the filler 51 increases, the filler 51 of small particle size intrudes into the gaps of the particles 50 of the fluororesin of large particle size in the raw material composition, and the filler 51 aggregates among the particles 50 of the fluororesin, and aggregates of the filler 51 having a particle size that increases to a size close to the thickness of the target sheet are likely to occur (see fig. 1 (b)). If the raw material composition containing the aggregate is fired, the particles 50 of the fluororesin are melted to form an integrated matrix, but the aggregate of the filler 51 remains directly. As a result, it was found that: when the molded article after firing is cut to form a thin sheet of about 100 μm, aggregates of the filler 51 are present in the molded article, and thus through holes (pinholes) are formed in the sheet.
The "cutting" refers to a method of continuously cutting out the sheet 30 in a thin manner by bringing the cutting edge 20 into contact with the surface of the blank 10 while rotating the blank 10 formed by sintering the compression molded body of the resin powder, as shown in fig. 3.
The sheet of the present embodiment contains the filler, thereby suppressing the thermal expansion coefficient to a low level and providing excellent thermal stability. The sheet of the present embodiment has an elongation at break exceeding 150% and excellent tensile properties. Thus, the sheet of the present embodiment has high thermal stability (low thermal expansion), and has high tensile properties.
The sheet according to the present embodiment can be obtained by using the following raw material composition (see fig. 2 (b): the raw material composition is obtained by mixing the filler 51 having the above-described predetermined particle diameter as a raw material with the particles 50' of the fluororesin having a small particle diameter (the particles 50' having a particle diameter smaller to the same extent as the particle diameter of the filler 51), and uniformly dispersing the particles 50' of the fluororesin and the filler 51. By uniformly dispersing the particles 50 'of the fluororesin and the filler 51 in the raw material composition, even when the mixing amount of the filler is increased, the filler 51 can be prevented from penetrating into the gaps between the particles 50' of the fluororesin and forming aggregates (the state of fig. 1 (b)). By suppressing the occurrence of aggregates, the occurrence of through-holes (pinholes) is suppressed in a sheet obtained by cutting a molded body obtained by firing the raw material composition. Therefore, the sheet obtained by cutting has high thermal stability (low thermal expansion) and high tensile properties.
The method of reducing the particle size of the fluororesin particles 50' to the same extent as the particle size of the filler 51 is described in detail in the method of producing a sheet according to one embodiment of the present invention.
(fluororesin)
As the fluororesin, a commonly used fluororesin, preferably Polytetrafluoroethylene (PTFE), can be used without particular limitation. Polytetrafluoroethylene (PTFE) is a homopolymer of tetrafluoroethylene.
As the fluororesin, modified polytetrafluoroethylene (modified PTFE) may be used. The modified polytetrafluoroethylene (modified PTFE) is preferably polytetrafluoroethylene modified with a perfluoroalkyl vinyl ether.
Examples of the perfluoroalkyl vinyl ether include perfluoroalkyl vinyl ethers represented by the following formula (1).
CF 2 ＝CF-OR f (1)
In the formula (1), R f Is a perfluoroalkyl group having 1 to 10 carbon atoms (preferably 1 to 5 carbon atoms) or a perfluoroorganic group represented by the following formula (2).
(in the formula (2), n is an integer of 1 to 4.)
Examples of the perfluoroalkyl group having 1 to 10 carbon atoms in the formula (1) include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group, and a perfluoropropyl group is preferable.
The content of the fluororesin contained in the sheet may be 50% by volume or more and 60% by volume or more and 70% by volume or less and may be 80% by volume or less, 70% by volume or less and 60% by volume or less.
If the content of the fluororesin is not less than the lower limit value, good strength can be obtained as a sheet.
In addition, if the content of the fluororesin is equal to or less than the upper limit value, the thermal expansion rate is suppressed to be low by the filler contained in the sheet, and excellent thermal stability can be obtained.
(filling Material)
The sheet of the present embodiment contains a filler. Examples of the filler include alumina, titanium oxide, silica, barium sulfate, silicon carbide, boron nitride, silicon nitride, glass fibers, glass beads, and mica.
As the filler, silica, boron nitride, and alumina can be preferably used from the viewpoint of imparting high thermal stability (low thermal expansion) to the sheet. For these fillers, 1 or 2 or more kinds may be used.
The content of the filler contained in the sheet is preferably 20% by volume or more, and may be 25% by mass or more, or may be 30% by mass or more.
The content of the filler contained in the sheet is preferably 50% by volume or less, and may be 48% by mass or less, 45% by mass or less, 40% by mass or less, or 30% by mass or less.
If the content of the filler in the sheet is not less than the lower limit value, the thermal expansion coefficient of the sheet is suppressed to a small value of, for example, 100 ppm/. Degree.C.or less, and the thermal stability is excellent.
In addition, if the content of the filler in the sheet is equal to or less than the upper limit value, the strength as the sheet can be sufficiently maintained, and good handleability can be obtained.
The filler has an average particle diameter of 20% or less relative to a predetermined thickness of the sheet. If the average particle diameter of the filler particles is within the above range, it is possible to contribute to suppression of occurrence of pinholes. The average particle diameter of the filler may be 18% or less, 15% or less, 12% or less, 10% or less, 8% or less, or 5% or less, relative to the predetermined thickness of the sheet. The specific thickness of the film thickness of the sheet will be described later.
The average particle diameter of the filler may be appropriately selected with respect to the desired thickness of the sheet, and is preferably, for example, 0.1 μm or more, but may be 0.2 μm or more, 0.3 μm or more, 0.5 μm or more, or 1 μm or more. The average particle diameter of the filler is preferably 10 μm or less, but may be 9 μm or less, 8 μm or less, 5 μm or less, or 3 μm or less. The average particle diameter of the filler is preferably 0.1 μm or more and 10 μm or less.
By setting the average particle diameter of the filler to the above range, aggregation of filler particles can be suppressed, and the percentage of coarse particles can be reduced, so that the occurrence of through holes (pinholes) in the sheet can be suppressed, and excellent tensile properties can be obtained.
In the present specification, the average particle diameter of the filler contained in the sheet is obtained by the following method: the particle diameters (diameter or longest diameter) of 100 filler particles arbitrarily selected were measured in a scanning electron microscope image obtained by observing the surface of a sheet at an acceleration voltage of 5kV and a magnification of 1000 times in the range of 100 μm in the horizontal direction by 100 μm in the vertical direction using a scanning electron microscope (SU 8220, manufactured by Hitachi Ltd.).
(optional ingredients)
In one embodiment, the sheet may also contain optional ingredients. The optional components are not particularly limited, and examples thereof include flame retardants, flame retardant aids, pigments, antioxidants, reflection-imparting agents, masking agents, lubricants, processing stabilizers, plasticizers, foaming agents, and the like.
In this case, the total content of the optional components in the sheet may be 20 mass% or less, 10 mass% or less, or 5 mass% or less.
In one embodiment, for example, the sheet is composed of polytetrafluoroethylene or modified polytetrafluoroethylene, and a filler, wherein the polytetrafluoroethylene or modified polytetrafluoroethylene accounts for 85 mass% or more, 90 mass% or more, 95 mass% or more, 98 mass% or more, 99 mass% or more, 99.5 mass% or more, 99.9 mass% or more, or 100 mass% or more, and the filler is 1 or more selected from alumina, titania, silica, glass fibers, glass beads, and mica.
(Property of sheet)
The sheet according to one embodiment of the present invention has a predetermined thickness, and preferably has a thickness in the range of 25 to 300. Mu.m. As a method for producing a sheet containing a fluororesin and a filler as main components, cutting can be given. Details of the cutting process and the method of manufacturing a sheet according to one embodiment of the present invention will be described later.
As a method for producing a sheet mainly composed of a fluororesin and a filler, a coating method, extrusion molding, calendaring, and the like are known in addition to the above-described cutting process. However, for example, in the case of producing a sheet by a coating method, the thickness of the sheet is generally limited to 25 μm, and if the thickness of the sheet is to be increased, overlapping coating is required, and the process becomes complicated.
In addition, when a sheet is produced by extrusion molding or rolling, the thickness of the obtained sheet is usually 1mm or so, and it is difficult to obtain a sheet having a thickness of 25 to 300 μm by extrusion molding or rolling.
The thickness of the sheet is preferably 25 μm or more, but may be 30 μm or more, 50 μm or more, 70 μm or more, or 100 μm or more. The thickness of the sheet is preferably 300 μm or less, but may be 200 μm or less, 150 μm or less, or 100 μm or less.
By setting the thickness of the sheet to 25 μm or more, the strength as a sheet can be sufficiently maintained, and good handleability can be obtained.
Further, by setting the thickness of the sheet to 300 μm or less, good flexibility can be obtained.
In the present specification, the term "thickness of the sheet" means an average value of thicknesses measured at positions of 10 points in the sheet.
In one embodiment, the elongation at break of the sheet exceeds 150%, may be 152% or more, may be 200% or more, may be 300% or more, may be 350% or more, or may be 380% or more.
Elongation at break was measured by the method described in the examples.
In one embodiment, the thermal expansion coefficient of the sheet may be less than 100 ppm/DEG C, or may be 40 ppm/DEG C or more and 90 ppm/DEG C or less, or may be 50 ppm/DEG C or more and 80 ppm/DEG C or less, or may be 60 ppm/DEG C or more and 70 ppm/DEG C or less.
The thermal expansion coefficient was measured by the method described in examples.
In one embodiment, the number of through holes (pinholes) having a diameter of 50 μm or more are present in the sheet per 100cm of the sheet 2 The surface area is preferably 25 or less, more preferably 20 or less, further preferably 15 or less, 10 or less, 5 or less, and preferably 0.
The number of through holes (pinholes) was measured by the method described in the examples.
[ base Material for printed Board ]
The substrate for a printed circuit board according to one embodiment of the present invention includes the sheet according to one embodiment of the present invention.
Since fluororesin has excellent heat resistance and insulation properties, it is expected to be applied as a heat-resistant material such as a heat-resistant insulating tape or a printed circuit board material. However, the conventional fluororesin sheet produced by cutting is liable to thermally shrink by heating or the like, and has poor dimensional stability, and thus, there is a problem that it is difficult to perform a processing such as bonding with other materials.
In contrast, the sheet according to one embodiment of the present invention has the advantage that the filler particles are uniformly dispersed in the fluororesin matrix, thereby suppressing thermal shrinkage and improving dimensional stability, and the sheet has an advantage that processing such as bonding with other materials is easier than conventional fluororesin sheets.
Examples of the substrate for a printed circuit board using the sheet according to one embodiment of the present invention include a substrate obtained by laminating a metal foil such as a copper foil on the sheet.
[ method for producing sheet ]
The method for producing a sheet according to one embodiment of the present invention includes the following steps (1) to (4):
(1) A step of preparing a raw material composition by mixing the following components (A') and (B),
(A') a fluororesin having an average particle diameter of 50% or less relative to a predetermined thickness of the sheet,
(B) A filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet;
(2) Forming a raw material composition into a cylindrical shape to form a molded body;
(3) Firing the molded article;
(4) And a step of performing a cutting process to cut the surface of the molded body after firing to form a sheet shape.
(Process (1) preparation of raw material composition)
As the fluororesin of the component (a'), the fluororesin of the component (a) described in the item of the sheet described above can be used.
The fluororesin to be used as the raw material has a particle shape, and the average particle diameter thereof is 50% or less relative to the predetermined thickness of the sheet, and may be appropriately selected according to the desired sheet thickness. The average particle diameter of the fluororesin particles is preferably 0.1 to 10. Mu.m.
By using the fluororesin particles within the above-mentioned average particle diameter range, a raw material composition in which the filler particles and the fluororesin particles are uniformly dispersed can be obtained.
The average particle diameter of the fluororesin particles may be 0.1 μm or more, or may be 0.2 μm or more, 1 μm or more, or 5 μm or more.
The average particle diameter of the fluororesin particles may be 10 μm or less or may be 5 μm or less.
As a method for setting the average particle diameter of the fluororesin particles to 50% or less, preferably in the range of 0.1 to 10 μm, relative to the predetermined thickness of the sheet, for example, there are given: a method of using a commercially available fluororesin particle dispersion (generally, having an average particle diameter in the range of 0.1 to 0.5 μm) in which fluororesin particles are dispersed in a solvent; and a method in which commercially available fluororesin particles in the form of powder (generally, having an average particle diameter in the range of 200 to 600 μm) are pulverized to thereby form the above average particle diameter. Details of the process using the fluororesin pellets obtained by the above 2 methods will be described later.
In the present specification, the average particle diameter of the fluororesin particles used for the production of the raw material composition can be measured under the condition of measuring the wind pressure of 1Bar using a particle size distribution measuring apparatus (MS-3000, manufactured by spectra corporation).
As the filler of the component (B), the filler described in the item of the sheet described above can be used.
The filler has a particle shape, and the preferable range of the average particle diameter and the reason thereof are the same as those described in the item of the sheet.
The average particle diameter of filler particles used in the preparation of the raw material composition can be measured by the same method as the average particle diameter of fluororesin particles.
As an embodiment of a method for obtaining a raw material composition by mixing the component (a') and the component (B), there is given: a method in which the solvent is removed from a raw material-containing solution obtained by dispersing the component (a') and the component (B) in the solvent, and then the obtained mixed powder is mixed by stirring with a stirrer or the like having blades.
Examples of the raw material-containing solution include: the component (B) is added to a dispersion liquid in which particles of a fluororesin (for example, PTFE) produced in a solvent by emulsion polymerization or the like are dispersed in the solvent, and then the resultant mixture is stirred and mixed by a stirrer or the like.
In this case, the particles of the fluororesin dispersed in the dispersion medium correspond to the component (a') (fluororesin particles having an average particle diameter of 50% or less relative to the predetermined thickness of the sheet).
The raw material-containing solution is not limited to the solution obtained by the above method, and may be, for example: after the fluororesin particles (component (a')) produced by emulsion polymerization or the like are separated from the solvent used in the polymerization, they are dispersed in another solvent to obtain a dispersion, and the dispersion is added with a solution obtained by adding component (B).
The solvent used in the dispersion is not particularly limited, and examples thereof include methyl ethyl ketone and water.
The amount of the component (B) to be mixed in the dispersion is such that the content of the component (a') and the content of the component (B) in the raw material composition obtained from the raw material-containing solution are each a desired percentage. The preferable range of the content of the component (a') contained in the raw material composition is the same as the preferable range of the content of the component (a) described in the item of the sheet. The preferable range of the content of the component (B) contained in the raw material composition is the same as the preferable range of the content of the component (B) described in the item of the sheet.
The stirring speed of the dispersion to which the component (B) is added is not particularly limited, and may be, for example, 100 to 800rpm or 200 to 600rpm.
The stirring time of the dispersion liquid to which the component (B) is added is not particularly limited, and may be, for example, 1 to 20 minutes or 2 to 18 minutes.
The method for removing the solvent from the raw material-containing solution is not particularly limited, and may be carried out, for example, by the following method: the component (a') and the component (B) contained in the raw material-containing solution are precipitated by coprecipitation or the like, separated from the raw material-containing solution, and then dried in a drying furnace, whereby the solvent component contained in the precipitate is volatilized and removed.
In the case of drying the precipitate by a drying furnace or the like, the drying temperature may be, for example, 60 to 400℃or 80 to 300 ℃.
When the mixed powder of the component (A') and the component (B) obtained after drying is stirred and mixed by a stirrer with blades or the like, the stirring speed is not particularly limited, and may be, for example, 1000 to 6000rpm or 2000 to 5000rpm.
The stirring time of the mixed powder obtained after drying is not particularly limited, and may be, for example, 1 to 15 minutes or 2 to 10 minutes.
As an embodiment of a method for obtaining a raw material composition by mixing component (a ') (fluororesin particles having an average particle diameter of 50% or less relative to the predetermined thickness of the sheet) and component (B) (filler having an average particle diameter of 20% or less relative to the predetermined thickness of the sheet), for example, a method of dry-mixing component (a') and component (B) may be employed.
Examples of the method for mixing the component (a') and the component (B) include: and a method in which the secondary particles obtained by agglomerating the primary particles of the fluororesin are crushed to obtain a fluororesin (component (A ')) having an average particle diameter of 0.1 to 10 μm, and then the component (A') and the component (B) are mixed by stirring with a stirrer or the like having blades.
The particle size of the secondary particles of the fluororesin is not particularly limited, and may be, for example, 100 to 800. Mu.m, 130 to 700. Mu.m, or 150 to 600. Mu.m.
The method of crushing the secondary particles is not particularly limited, and examples thereof include a method using a crusher such as a mixer crusher, a jet mill, and a freeze mill.
The component (a ') and the component (B) are mixed so that the content of the component (a') and the content of the component (B) contained in the raw material composition become a desired percentage, respectively. The preferable range of the content of the component (a') contained in the raw material composition is the same as the preferable range of the content of the component (a) described in the item of the sheet. The preferable range of the content of the component (B) contained in the raw material composition is the same as the preferable range of the content of the component (B) described in the item of the sheet.
The stirring speed of the component (A') and the component (B) during the dry mixing is not particularly limited, and may be, for example, 1000 to 6000rpm or 2000 to 5000rpm.
The stirring time of the component (a') and the component (B) in the dry mixing is not particularly limited, and may be, for example, 1 to 15 minutes or 2 to 10 minutes.
In addition to the component (a') and the component (B), optional components may be mixed in the raw material composition. As the optional components, the optional components described in the item of the sheet may be used.
The preferable range of the mixing amount of the optional components may be set to the same range as the preferable range of the content of the optional components described in the item of the sheet described above.
(step (2) formation of molded article)
The raw material composition is molded into a cylindrical shape to form a molded body. Examples of the method for forming the molded article include: and a method of filling the above-mentioned raw material composition into a mold and performing compression molding to form a cylindrical compression molded body.
The surface pressure may be 10 to 100MPa, 20 to 60MPa, or 30 to 50MPa.
The raw material composition obtained by mixing the component (a') and the component (B) is compression molded to obtain a compression molded article in which the fluororesin particles and the filler are uniformly dispersed (see fig. 2B).
(step (3) firing of the molded article)
The obtained compression molded body was fired to obtain a blank. The firing temperature may be 100 to 400 ℃, 350 to 370 ℃, or 360 to 370 ℃.
The obtained preform is a molded article obtained by integrating the burned product of the raw material powder.
The molded article is fired to form a state in which filler particles are uniformly dispersed in a matrix (matrix) formed by melting and integrating the respective fluororesin particles in the molded article.
By firing the compressed compact of the raw material composition in which the component (a') and the component (B) are mixed, it is possible to suppress the formation of aggregates of the filler and to obtain a good blank having few coarse particles.
The blank (molded article) is preferably cylindrical in shape from the viewpoint of facilitating the cutting process described later. In the case where the blank (molded article) is a cylindrical body, the diameter of the cylindrical body may be, for example, 100 to 500mm or 150 to 500mm.
(step (4) forming a sheet by cutting)
Then, a cutting process is performed, that is, the surface of the blank, which is the molded body after firing, is cut to form a sheet shape.
As shown in fig. 3, when the blank (molded article) is a cylindrical body, the cutting edge is cut by abutting against the longitudinal outer peripheral surface of the fired cylindrical body, thereby forming a sheet shape.
As described above, the blank obtained by using the raw material composition obtained by mixing the component (a') and the component (B) is a good blank having few coarse particles in which filler particles are aggregated, and therefore, by cutting the blank, the generation of through holes (pinholes) can be suppressed, and a sheet excellent in tensile properties can be obtained.
In the case where the blank (molded article) is a cylindrical body, the outer peripheral surface, the inner peripheral surface, and the end surface of the fired cylindrical body may be removed from the outside of the surface by a thickness of 3mm before the step of cutting the longitudinal outer peripheral surface of the fired cylindrical body to form a sheet shape.
The cutting process of cutting the longitudinal outer peripheral surface of the fired cylindrical body to form a sheet shape can be performed using the apparatus shown in fig. 3. The thickness of the sheet obtained by cutting may be appropriately selected depending on the purpose of use of the sheet, and may be, for example, 25 μm or more, 30 μm or more, 50 μm or more, 70 μm or more, or 100 μm or more. The thickness of the cut sheet is, for example, 300 μm or less, and may be 200 μm or less, 150 μm or less, or 100 μm or less.
In fig. 3, a sintered blank (cylindrical body) 10 is rotated, and cut by a cutting edge (cutter) 20 to form a sheet 30.
The blank obtained through the steps (1) to (3) is cut to obtain a sheet having a thickness of 25 to 300. Mu.m.
The sheet according to the present embodiment described above is suitable for use as, for example, a heat-resistant material such as a heat-resistant insulating tape, a base material for a printed board, and a release sheet.
Examples (example)
(preparation of raw material composition)
Production example 1
The PTFE dispersion (dispersion liquid in which PTFE particles are dispersed in a solvent) and spherical silica (average particle diameter 1 μm) as a filler are mixed so that the volume ratio of the PTFE particles to the spherical silica contained in the PTFE dispersion becomes a ratio of PTFE particles to spherical silica=6:4, and the mixture is stirred and mixed at a rotation speed of 300 to 500rpm for 5 to 15 minutes using a stirrer, to obtain a raw material-containing solution.
While stirring the raw material-containing solution with a stirrer, ethanol was further added to the raw material-containing solution to coprecipitate PTFE particles and spherical silica. Drying the coprecipitate in a drying furnace at 100-200 ℃ and volatilizing to remove the solvent, thereby obtaining dry powder.
The obtained dry powder was mixed with a stirrer having a rotating blade at a rotational speed of 3000 to 4000rpm for 0.5 to 1 minute to obtain a raw material composition 1 containing PTFE powder (average particle diameter: 0.25 μm) and spherical silica (average particle diameter: 1 μm).
Production example 2
Polytetrafluoroethylene (PTFE) powder (average particle diameter 400 μm) was pulverized to obtain PTFE powder having an average particle diameter of 5 μm.
The PTFE powder having an average particle diameter of 5 μm and spherical silica (average particle diameter of 3 μm) as a filler obtained in the above were mixed so that the volume ratio became a ratio of PTFE powder to spherical silica=6:4, and mixed at a rotational speed of 3000 to 4000rpm for 3 to 7 minutes using a stirrer with a rotating blade, to obtain a raw material composition 2 containing PTFE powder (average particle diameter: 5 μm) and spherical silica (average particle diameter: 3 μm).
Production example 3
The PTFE powder (average particle diameter 400 μm) and the spherical silica (average particle diameter 1 μm) as the filler (filler) were mixed so that the volume ratio became a ratio of PTFE powder to spherical silica=6:4, and mixed at a rotational speed of 3000 to 4000rpm for 3 to 7 minutes using a stirrer with a rotating blade, to obtain a raw material composition 3 containing the PTFE powder (average particle diameter: 400 μm) and the spherical silica (average particle diameter: 1 μm).
Example 1
< manufacture of blank >
600g of the raw material composition 1 was charged into a cylindrical mold, and compression molded at a pressing pressure of 30MPa from the upper portion for 3 minutes to obtain a cylindrical preform (outer diameter 67 mm. Times.inner diameter 33 mm). The obtained preform was charged into a firing furnace and fired at 365℃for 6 hours.
< cutting process >)
The obtained cylindrical fired body (outer diameter 67 mm. Times.inner diameter 33 mm) was subjected to cutting processing at a cutting speed of 8m/min and a target thickness of 100 μm by using the apparatus shown in FIG. 3, to produce a sheet having a thickness of 100. Mu.m.
Example 2
A sheet was produced in the same manner as in example 1, except that the raw material composition 2 was used instead of the raw material composition 1.
Comparative example 1
A sheet was produced in the same manner as in example 1, except that the raw material composition 3 was used instead of the raw material composition 1.
Reference example 1
A PTFE sheet containing no filler material ("TOMBONo 9001", manufactured by japan neon corporation) was prepared.
[ evaluation method ]
(dispersion state of filler)
The surface areas of the sheets obtained in example 2 and comparative example 1 were subjected to elemental mapping analysis at an acceleration voltage of 15kV using an energy dispersive X-ray analyzer (manufactured by horiba, inc. 'E-Max N').
The results of the elemental mapping analysis of the sheets of example 2 and comparative example 1 are shown in fig. 4 and 5, respectively.
The result of the element mapping analysis shown in fig. 4 can be confirmed as follows: in the sheet obtained in example 2, spherical silica Si (black part) was uniformly dispersed in the PTFE resin (gray part).
On the other hand, from the result of the element mapping analysis shown in fig. 5, it can be confirmed that: in the sheet obtained in comparative example 1, aggregates Si (black portions) formed by agglomerating spherical silica Si (black portions) were present in the PTFE resin (gray portions), and through holes (pinholes) (portions surrounded by broken lines) were generated during cutting.
(number of through holes (pinholes))
The sheets obtained in examples 1 to 2 and comparative example 1 were collected from any position (for example, the center part in the short side direction, the sheet center part at a position midway except the end part in the long direction of the long sheet) for counting 100cm in surface area 2 The number of through-holes (pinholes) having a longest diameter of 50 μm or more was counted by performing an enlarged observation using a microscope (manufactured by KEYENCE, VHX-5000). The results are shown in table 1.
(elongation at break)
The sheets obtained in examples 1 to 2 and comparative example 1 were used as the width of the measurement site: 10mm, inter-chuck distance (inter-comment distance) L0: the sample for measuring the elongation at break was cut out at 22.25mm, and the sheet was stretched to break at a stretching speed of 200mm/min under an environment of 23℃and 50% RH using a tensile tester (manufactured by Shimadzu corporation, "Ez-LX"), and the elongation at break was calculated from the distance L1 (mm) between the marks at the time of breaking by the following formula (3). The results are shown in table 1.
Elongation at break= (L1-L0)/l0×100% (3)
(thermal expansion Rate)
The raw material compositions 1 to 3 were filled into a mold having a longitudinal direction of 5mm×a transverse direction of 5mm, and compression molded under a molding surface pressure (pressing pressure) of 30MPa for 1 minute to obtain a molded article having a cubic shape with one side of 5 mm. The molded article was fired at 360℃for 6 hours, and the thermal expansion coefficient of the obtained fired article (thermal expansion coefficient measurement specimen) was measured by using a thermal mechanical measuring device (TMA) (manufactured by TA Instruments Japan Co., ltd., "Q400"). The thermal expansion rate was measured as follows: the follow load was set to 0.05N, the measured temperature was set from room temperature to 200℃and the temperature was raised at a temperature raising rate of 5℃per minute. The thermal expansion coefficient was calculated from the thermal expansion amount in the range of 50 to 150℃in the measurement from room temperature to 200 ℃.
TABLE 1
[ possibility of industrial use ]
The sheet of the present invention is suitable for use as a heat-resistant material such as a heat-resistant insulating tape, a base material for a printed board, and a release sheet, but is not limited thereto.
While the present embodiments and/or examples have been described in detail, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments and/or examples without materially departing from the novel teachings and advantages of this invention. Accordingly, these numerous modifications are also included within the scope of the present invention.
The contents of the documents described in this specification and the application based on the paris treaty as the priority basis of the present application are incorporated herein by reference in their entirety.

Claims (17)

1. A sheet material, wherein,
comprises the following components (A) and (B),
(A) A fluororesin, which is composed of a fluorine-containing resin,
(B) A filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet,
the elongation at break of the sheet is over 150%.
2. The sheet according to claim 1, wherein,
the sheet has a predetermined thickness of 25 to 300 [ mu ] m.
3. The sheet according to claim 1 or 2, wherein,
the average particle diameter of the filling material is 0.1-10 mu m.
4. The sheet according to claim 1 or 2, wherein,
the mixing proportion of the filling material is 20-50% by volume.
5. The sheet according to claim 1 or 2, wherein,
the fluororesin is PTFE or modified PTFE, wherein PTFE represents polytetrafluoroethylene.
6. The sheet according to claim 1 or 2, wherein,
the filling material is at least one selected from aluminum oxide, titanium oxide, silicon dioxide, barium sulfate, silicon carbide, boron nitride, silicon nitride, glass fiber, glass beads and mica.
7. The sheet according to claim 1 or 2, wherein,
the sheet has a thermal expansion of less than 100ppm/°c.
8. The sheet according to claim 1 or 2, wherein,
the number of through holes with a diameter of 50 μm or more in the sheet is equal to or greater than 100cm of the sheet 2 The surface area is 25 or less.
9. A substrate for a printed board, wherein,
a sheet comprising the sheet according to any one of claims 1 to 8.
10. A method for producing a sheet, wherein,
comprising the following steps:
a step of preparing a raw material composition by mixing the following components (A') and (B);
forming the raw material composition into a cylindrical shape to form a molded body;
a step of firing the molded article; and
a step of cutting the surface of the molded body after firing to form a sheet,
wherein,
a fluororesin having an average particle diameter of 50% or less relative to a predetermined thickness of the sheet, and a filler having an average particle diameter of 20% or less relative to a predetermined thickness of the sheet.
11. The method for producing a sheet according to claim 10, wherein,
the sheet has a predetermined thickness of 25 to 300 [ mu ] m.
12. The method for producing a sheet according to claim 10 or 11, wherein,
the fluororesin particles have an average particle diameter of 0.1 to 10 [ mu ] m.
13. The method for producing a sheet according to claim 10 or 11, wherein,
the average particle diameter of the filling material is 0.1-10 mu m.
14. The method for producing a sheet according to claim 10 or 11, wherein,
the mixing proportion of the filling material is 20-50% by volume.
15. The method for producing a sheet according to claim 10 or 11, wherein,
the process for preparing the raw material composition comprises the following steps:
and (B) a step of removing the solvent from a raw material-containing solution obtained by dispersing in the solvent a fluororesin having an average particle diameter of 50% or less relative to the predetermined thickness of the sheet and a filler having an average particle diameter of 20% or less relative to the predetermined thickness of the sheet.
16. The method for producing a sheet according to claim 10 or 11, wherein,
the step of preparing the raw material composition is a step of dry-mixing the fluororesin having an average particle diameter of 50% or less relative to the predetermined thickness of the sheet and the filler having an average particle diameter of 20% or less relative to the predetermined thickness of the sheet.
17. A sheet material, wherein,
the sheet obtained by the production method according to any one of claims 10 to 16.
CN202310725390.8A 2022-06-24 2023-06-19 Sheet, base material for printed board, and method for producing sheet Pending CN117285786A (en)

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