Method for manufacturing a powder dispersion and a composite

Abstract

The present invention provides a powder dispersion liquid containing a tetrafluoroethylene-based polymer, a prescribed polyoxyalkylene-modified polydimethylsiloxane, and a liquid dispersion medium, and a composite having a fired product with a high degree of the properties of the tetrafluoroethylene-based polymer. The powder dispersion liquid of the present invention contains a tetrafluoroethylene-based polymer powder, a liquid dispersion medium, and a polyoxyalkylene-modified polydimethylsiloxane having a weight average molecular weight of 3000 or less and an HLB value of 1 to 18 calculated by the Griffin formula. The composite of the present invention can be produced by applying the powder dispersion liquid of the present invention to a surface and heating.

Description

Technical Field

[0001] The present invention relates to a method for producing a powder dispersion and a composite. Background Art

[0002] Printed wiring boards (PCBs) used to transmit high-frequency signals require excellent transmission characteristics. Tetrafluoroethylene-based polymers, which have low relative permittivity and dielectric loss tangent, have attracted considerable attention as materials for insulating layers of PCBs with high transmission characteristics. Powder dispersions comprising tetrafluoroethylene-based polymer powder and a liquid dispersion medium are known as materials for forming insulating layers containing such polymers.

[0003] Tetrafluoroethylene polymers generally have low surface tension, and their powders have low dispersibility. In order to improve the dispersion stability of powder dispersions, Patent Documents 1, 2, and 3 each propose the incorporation of a specific surfactant.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-161616

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-082437

[0008] Patent Document 3: International Publication No. 2014 / 010968 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] However, such powder dispersions are prone to foaming, resulting in poor workability when preparing them, mixing them with other components such as resin varnishes, and applying them. Furthermore, long-term storage of such dispersions requires management of liquid properties such as pH, viscosity, and uniformity.

[0011] Furthermore, to obtain these powder dispersions with excellent physical properties and dispersion stability, other additives are often required, making the preparation more complicated. This problem is particularly pronounced when using silicone surfactants or highly fibrillated polytetrafluoroethylene powders.

[0012] Furthermore, when a fired product is produced from such a powder dispersion, the residual or decomposed surfactant is likely to cause deterioration in physical properties such as electrical characteristics and surface smoothness of the fired product.

[0013] The present invention aims to provide a powder dispersion having excellent dispersion stability, handleability, and long-term storage properties, from which a composite having a fired product having excellent physical properties based on a tetrafluoroethylene polymer can be easily produced.

[0014] Technical solutions used to solve technical problems

[0015] The present invention has the following technical contents.

[0016] [1] A powder dispersion comprising a tetrafluoroethylene polymer powder, a liquid dispersion medium, and a polyoxyalkylene-modified polydimethylsiloxane having a weight-average molecular weight of 3,000 or less and an HLB value of 1 to 18 as calculated by the Griffin equation.

[0017] [2] The powder dispersion according to [1], wherein the static surface tension of the polyoxyalkylene-modified polydimethylsiloxane is 28 mN / m or less.

[0018] [3] The powder dispersion according to [1] or [2], wherein the dynamic surface tension of the polyoxyalkylene-modified polydimethylsiloxane is 40 mN / m or less.

[0019] [4] The powder dispersion according to any one of [1] to [3], wherein the HLB value of the polyoxyalkylene-modified polydimethylsiloxane is 10-16.

[0020] [5] The powder dispersion according to any one of [1] to [4], wherein the molecular weight dispersity of the polyoxyalkylene-modified polydimethylsiloxane is less than 2.0.

[0021] [6] The powder dispersion according to any one of [1] to [5], wherein the degree of polymerization of the oxyalkylene groups in the polyoxyalkylene-modified polydimethylsiloxane is 2-100 and the degree of polymerization of dimethylsiloxane is 2-100.

[0022] [7] The powder dispersion according to any one of [1] to [6], wherein the polyoxyalkylene-modified polydimethylsiloxane is a polyoxyalkylene-modified polydimethylsiloxane containing a dimethylsiloxane unit in a main chain and having an oxyalkylene group in a side chain.

[0023] [8] The powder dispersion according to any one of [1] to [6], wherein the polyoxyalkylene-modified polydimethylsiloxane is a polyoxyalkylene-modified polydimethylsiloxane comprising a dimethylsiloxane unit in the main chain and having an oxyalkylene group at a main chain terminal.

[0024] [9] The powder dispersion according to any one of [1] to [8], wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer comprising perfluoro(alkyl vinyl ether)-based units and containing 1 to 5 mol% of perfluoro(alkyl vinyl ether)-based units relative to all units and having a melting temperature of 260 to 320°C.

[0025]

[10] A powder dispersion as described in any one of [1] to [9], wherein the powder contains a first powder of polytetrafluoroethylene and a second powder of a tetrafluoroethylene-based polymer containing units based on perfluoro(alkyl vinyl ether) and containing 1-5 mol% of units based on perfluoro(alkyl vinyl ether) relative to all units and having a melting temperature of 260-320°C, and the proportion of the second powder in the total of the first powder and the second powder is less than 25% by mass.

[0026]

[11] The powder dispersion according to any one of [1] to

[10] , further comprising at least one nonionic surfactant selected from ester surfactants, ether surfactants, ester ether surfactants, alkanolamide surfactants, alkyl glycosides and higher alcohols.

[0027]

[12] The powder dispersion according to any one of [1] to

[11] , wherein the liquid dispersion medium contains water.

[0028]

[13] The powder dispersion according to

[12] , wherein the pH of the powder dispersion is 6-12.

[0029]

[14] A powder dispersion comprising a tetrafluoroethylene polymer powder, a polyoxyalkylene-modified polydimethylsiloxane having a dimethylsiloxane unit in the main chain and an oxyalkylene group in the side chain, or a polyoxyalkylene-modified polydimethylsiloxane having a dimethylsiloxane unit in the main chain and an oxyalkylene group at the end of the main chain, and a liquid dispersion medium comprising at least water, wherein the viscosity of the liquid dispersion medium is less than 400 mPa·s.

[0030]

[15] A method for producing a composite, comprising applying the powder dispersion described in any one of [1] to

[14] to a substrate surface and heating the substrate surface to produce a calcined product of the tetrafluoroethylene polymer, thereby obtaining a composite having the substrate and the calcined product.

[0031] Effects of the Invention

[0032] According to the present invention, a tetrafluoroethylene polymer powder dispersion having excellent dispersion stability, handleability, and long-term storage properties can be obtained. Furthermore, according to the present invention, a composite of a fired product having excellent physical properties such as surface smoothness while possessing high electrical and other properties typical of tetrafluoroethylene polymers can be obtained. DETAILED DESCRIPTION

[0033] The following terms have the following meanings.

[0034] The average particle size (D50) is the volume-based cumulative 50% diameter of a target object, such as a powder or filler, as determined by laser diffraction scattering. Specifically, the particle size distribution is measured by laser diffraction scattering, and a cumulative curve is calculated, with the total volume of the particle group as 100%. This is the particle size at the point where the cumulative volume reaches 50%.

[0035] The "melting temperature" refers to the temperature corresponding to the maximum value of the melting peak of a polymer measured by differential scanning calorimetry (DSC).

[0036] The “glass transition temperature (Tg)” is a value measured by analyzing a polymer using a dynamic viscoelasticity measurement (DMA) method.

[0037] The "viscosity of the powder dispersion" is the viscosity measured using a Brookfield viscometer at 25°C and 60 rpm. The measurement was repeated three times, and the average of the three measured values ​​was calculated.

[0038] The "thixotropic ratio of the powder dispersion" is calculated by dividing the viscosity measured at a rotational speed of 30 rpm by the viscosity measured at a rotational speed of 60 rpm. Each viscosity measurement was repeated three times, and the average of the three measured values ​​was calculated.

[0039] The “specific surface area of ​​the powder” is a value calculated by measuring the powder using a gas adsorption (constant volume method) BET multipoint method, and was determined using NOVA4200e (manufactured by Quantachrome Instruments).

[0040] The “weight average molecular weight of the polyoxyalkylene-modified polydimethylsiloxane” is determined as a weight average molecular weight in terms of polystyrene in gel permeation chromatography (GPC) analysis.

[0041] The "HLB value of polyoxyalkylene-modified polydimethylsiloxane" is a value calculated by Griffin's equation and is obtained by multiplying the value obtained by dividing the molecular weight of the polyoxyalkylene portion in the molecule by the molecular weight of the organopolysiloxane by 20.

[0042] The “static surface tension” was determined by the Wilhelmy method using an automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) using a 0.1% by mass aqueous solution of polyoxyalkylene-modified polydimethylsiloxane.

[0043] "Dynamic surface tension" is the dynamic surface tension of a 0.1% by mass aqueous solution of polyoxyalkylene-modified polydimethylsiloxane at 25°C at a bubble generation cycle of 6 Hz using the maximum bubble pressure method. This value is measured by immersing the sensor of a dynamic surface tensiometer θt60 manufactured by Eiko Seiki Co., Ltd. in the aqueous solution.

[0044] A "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of that monomer. A unit may be formed directly through a polymerization reaction, or it may be formed by treating the polymer to convert a portion of the unit into a different structure. Hereinafter, a unit based on monomer a will be simply referred to as a "monomer a unit."

[0045] The powder dispersion of the present invention (hereinafter also referred to as the "present dispersion") comprises a powder (hereinafter also referred to as the "F powder") of a tetrafluoroethylene-based polymer (hereinafter also referred to as the "F polymer"), a liquid dispersion medium, and a polyoxyalkylene-modified polydimethylsiloxane having a weight-average molecular weight of 3000 or less and an HLB value of 1-18 as calculated by the Griffin equation, wherein the F powder is dispersed in particulate form. The polyoxyalkylene-modified polydimethylsiloxane is a nonionic compound.

[0046] The present dispersion has excellent dispersion stability, handleability, and long-term storage properties. The fired product formed from the present dispersion has excellent physical properties based on the tetrafluoroethylene polymer, such as electrical properties, and also has excellent surface smoothness.

[0047] The reason for this is not clear, but is believed to be as follows.

[0048] When a nonionic surfactant is used in an F powder dispersion, it interacts with the F powder surface, improving the dispersion stability of the F powder. At the same time, it concentrates on the liquid surface of the dispersion, weakening the surface tension of the dispersion. Consequently, the dispersion's defoaming properties deteriorate, handling properties decrease, and compatibility with other materials is likely to decline.

[0049] In particular, silicone surfactants, due to their molecular structure, generally exhibit insufficient interaction with F powder, making this tendency more pronounced. For example, to maximize the dispersion stability of F powder, the amount of surfactant added must be increased, which inevitably reduces the handling and mixing properties of the dispersion.

[0050] The polyoxyalkylene-modified polydimethylsiloxane in this dispersion is a nonionic compound with a relatively low weight-average molecular weight and an HLB value within a specified range. It can be said to be a silicone surfactant with a highly balanced hydrophobicity and hydrophilicity.

[0051] This polyoxyalkylene-modified polydimethylsiloxane is believed to enhance interaction with the F powder due to its short polymer chain length, which facilitates coverage of the F powder surface. Specifically, it is believed that the high adhesion of this polyoxyalkylene-modified polydimethylsiloxane to the F powder selectively enhances dispersion stability in the present dispersion and suppresses deterioration in liquid physical properties.

[0052] Furthermore, since polyoxyalkylene-modified dimethylsiloxane with a relatively low weight-average molecular weight is excellent in thermal decomposition, it is easily decomposed when the present dispersion is heated to form a burned product. As a result, the burned product is likely to have high physical properties based on the F polymer.

[0053] The F polymer of the present invention is a polymer containing units (hereinafter also referred to as "TFE units") derived from tetrafluoroethylene (hereinafter also referred to as "TFE").

[0054] The F polymer may be heat-fusible or non-heat-fusible.

[0055] The melting temperature of the heat-meltable F polymer is preferably 180°C or higher, more preferably 200-325°C, and even more preferably 260-320°C.

[0056] The melt viscosity of the F polymer at 380°C is preferably 1×10 2 -1×10 6 Pa·s.

[0057] The glass transition temperature of the F polymer is preferably 30-150°C, more preferably 75-125°C.

[0058] The fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass.

[0059] Examples of the F polymer include polytetrafluoroethylene (hereinafter also referred to as "PTFE"), polymers comprising TFE units and units based on ethylene (hereinafter also referred to as "ETFE"), polymers comprising TFE units and units based on propylene, polymers comprising TFE units and units based on perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE") (hereinafter also referred to as "PAVE units") (hereinafter also referred to as "PFA"), polymers comprising TFE units and units based on hexafluoropropylene (hereinafter also referred to as "HFP") (hereinafter also referred to as "FEP"), polymers comprising TFE units and units based on fluoroalkylethylene, and polymers comprising TFE units and units based on chlorotrifluoroethylene. PFA or FEP is preferred, and PFA is more preferred. These polymers may further contain units based on other comonomers.

[0060] Examples of PTFE include low-molecular-weight PTFE and modified PTFE. Low-molecular-weight PTFE and modified PTFE also include copolymers of TFE and a very small amount of a comonomer (such as HFP, PAVE, and FAE).

[0061] As PAVE, CF2=CFOCF3, CF2=CFOCF2CF3 or CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE") is preferred, and PPVE is more preferred.

[0062] The polymer F preferably has an oxygen-containing polar group. In this case, the dispersion stability of the present dispersion tends to be excellent, and the fired product such as the polymer layer obtained from the present dispersion tends to have excellent physical properties such as electrical properties, surface smoothness, and adhesion.

[0063] The oxygen-containing polar group may be contained in a monomer unit of the polymer F or in a terminal group of the main chain of the polymer F. As the latter embodiment, the polymer F may include an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like.

[0064] The oxygen-containing polar group is preferably a hydroxyl-containing group or a carbonyl-containing group, more preferably a carbonyl-containing group.

[0065] The hydroxyl-containing group is preferably an alcoholic hydroxyl-containing group, more preferably -CF2CH2OH or -C(CF3)2OH.

[0066] The carbonyl-containing group is a group containing a carbonyl group (>C(O)), preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH2), an anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.) or a carbonate group (-OC(O)O-), and more preferably an anhydride residue.

[0067] In the case where the F polymer has a carbonyl group, the number of carbonyl groups in the F polymer is preferably 6 The number of main chain carbon atoms is 10-5000, more preferably 50-4000, and further preferably 100-2000. In this case, the dispersion stability, operability and long-term storage properties of the present dispersion are easily excellent. In addition, the number of carbonyl groups in the F polymer can be quantified according to the composition of the polymer or the method described in International Publication No. 2020 / 145133.

[0068] The F polymer is preferably a tetrafluoroethylene polymer having a melting temperature of 260-320°C and containing PAVE units at 1-5 mol% relative to the total units. More preferably, it is a polymer (1) containing PAVE units at 1.5-3 mol% relative to the total monomer units and having an oxygen-containing polar group, or a polymer (2) containing PAVE units at 2-5 mol% relative to the total monomer units and not having an oxygen-containing polar group. These polymers form microspherulites in a fired product such as a polymer layer, and thus the properties of the resulting fired product are easily improved.

[0069] The polymer (1) preferably comprises TFE units, PAVE units, units based on a monomer having a hydroxyl group or a carbonyl group, or a polymer comprising TFE units and PAVE units and having a hydroxyl group or a carbonyl group at a main chain terminal, and the former is more preferred. The polymer (1) preferably comprises 94 to 98.49 mol% of TFE units, 1.5 to 3 mol% of PAVE units, and 0.01 to 3 mol% of units based on the above monomers, relative to the total units.

[0070] Furthermore, the above-mentioned monomer is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic anhydride (also known as nadic anhydride; hereinafter also referred to as "NAH").

[0071] Specific examples of the polymer (1) include the polymers described in International Publication No. 2018 / 16644.

[0072] The polymer (2) is preferably composed of only TFE units and PAVE units, and contains 95 to 98 mol% of TFE units and 2 to 5 mol% of PAVE units based on all monomer units.

[0073] The content of the PAVE unit in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, based on the total monomer units.

[0074] The polymer (2) does not have an oxygen-containing polar group, which means that per 1×10 6 The number of carbon atoms constituting the polymer backbone is less than 500. The number of oxygen-containing polar groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of oxygen-containing polar groups is usually 0.

[0075] Polymer (2) can be produced using a polymerization initiator or chain transfer agent that does not generate an oxygen-containing polar group as a terminal group of the polymer chain, or by fluorinating a polymer F having an oxygen-containing polar group. As a method for fluorination, a method using fluorine gas can be cited (see Japanese Patent Laid-Open No. 2019-194314, etc.).

[0076] The F powder in the present invention is a powder containing an F polymer. The content of the F polymer in the F powder is preferably 80% by mass or more, more preferably 100% by mass.

[0077] The F powder may be a single type or two or more types. When using two types of F powder, it is preferred to use a first powder of PTFE in combination with a second powder of an F polymer containing PAVE units at a melting temperature of 260-320°C, comprising 1-5 mol% of PAVE units relative to the total units. In this case, the proportion of the second powder in the total of the first and second powders is preferably 25% by mass or less, more preferably 15% by mass or less. Furthermore, the proportion in this case is preferably 0.1% by mass or more, more preferably 1% by mass or more.

[0078] This dispersion easily provides an adhesive fired product having excellent dispersion stability, handleability, and long-term storage properties and excellent physical properties based on PTFE.

[0079] In this case, the preferred embodiment is one in which the D50 of the first powder is 0.1-1 μm and the D50 of the second powder is 0.1-1 μm, or one in which the D50 of the first powder is 0.1-1 μm and the D50 of the second powder is 1-4 μm. The second powder may be a powder of the polymer (1) or a powder of the polymer (2), and preferably a powder of the polymer (1).

[0080] The F powder may contain a polymer different from the F polymer or an inorganic substance.

[0081] Examples of different polymers include aromatic polyesters, polyamideimides, polyimides, polyphenylene ethers, polyphenylene ethers, and maleimides.

[0082] Examples of the inorganic substance include silicon oxide (silicon dioxide), metal oxides (beryllium oxide, cerium oxide, aluminum oxide, basic aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride, and magnesium metasilicate (talc).

[0083] The F powder containing a polymer or inorganic substance different from the F polymer preferably has a core-shell structure having the F polymer as a core and a polymer or inorganic substance different from the F polymer as a shell, or a core-shell structure having the F polymer as a shell and a polymer or inorganic substance different from the F polymer as a core. Such F powder can be obtained, for example, by causing a powder of the F polymer and a powder of the polymer or inorganic substance different from the F polymer to bond together by collision or agglomeration.

[0084] The D50 of the F powder is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 8 μm or less. The D50 of the F powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. In particular, when the F polymer is polymer (1), the D50 of the F powder in the present dispersion is preferably 1 to 8 μm.

[0085] When the F powder includes the first powder and the second powder, D50 of the F powder is preferably 0.1 to 5 μm, more preferably 0.1 to 3 μm.

[0086] The specific surface area of ​​F powder is preferably 1-8m 2 / g, more preferably 1-3m 2 Even with such a small D50 fine-particle F powder, the dispersion liquid is likely to have excellent dispersion stability, handling properties and long-term storage properties due to the above-mentioned mechanism of action.

[0087] The polyoxyalkylene-modified dimethylsiloxane of the present invention is an organopolysiloxane having a polyoxyalkylene structure as a hydrophilic group and a polydimethylsiloxane structure as a hydrophobic group, and is preferably a linear polymer.

[0088] The weight-average molecular weight of the polyoxyalkylene-modified dimethylsiloxane is 3000 or less, preferably 2500 or less, and more preferably 2000 or less. The weight-average molecular weight is preferably 100 or greater, and more preferably 500 or greater. In this case, due to the aforementioned mechanism of action, the present dispersion tends to exhibit excellent dispersion stability, handleability, and long-term storage properties. Furthermore, due to its excellent thermal decomposition properties, the physical properties of the fired product tend to be improved.

[0089] The number average molecular weight of the polyoxyalkylene-modified dimethylsiloxane is preferably 3000 or less, more preferably 1500 or less. The number average molecular weight is preferably 100 or more, more preferably 500 or more.

[0090] The molecular weight dispersion of the polyoxyalkylene-modified dimethylsiloxane is preferably less than 2.0, more preferably 1.8 or less. The lower limit of the molecular weight dispersion is preferably greater than 1.0.

[0091] The HLB value of the polyoxyalkylene-modified dimethylsiloxane is 1-18, preferably 3 or higher, more preferably 6 or higher, further preferably 10 or higher, and particularly preferably 12 or higher. The HLB value is preferably 16 or lower, more preferably 15 or lower.

[0092] The static surface tension of the polyoxyalkylene-modified dimethylsiloxane is preferably 28 mN / m or less, more preferably 26 mN / m or less, and preferably 15 mN / m or more, more preferably 20 mN / m or more.

[0093] The dynamic surface tension of the polyoxyalkylene-modified dimethylsiloxane is preferably 40 mN / m or less, more preferably 35 mN / m or less, and the dynamic surface tension is preferably 20 mN / m or more.

[0094] The polyoxyalkylene-modified dimethylsiloxane may have a dimethylpolysiloxane unit (-(CH3)2SiO 2 / 2-), may have a dimethylpolysiloxane unit in the side chain, or may have a dimethylpolysiloxane unit in both the main chain and the side chain.

[0095] The polyoxyalkylene-modified polydimethylsiloxane is preferably one comprising a dimethylsiloxane unit in the main chain and an oxyalkylene group in the side chain, or one comprising a dimethylsiloxane unit in the main chain and an oxyalkylene group at the main chain terminal.

[0096] The former polyoxyalkylene-modified polydimethylsiloxane preferably comprises a compound of the formula -(R 1 )(R 2 )SiO 2 / 2 - represents a diorganosiloxane unit.

[0097] R in the formula 1 represents an alkyl group, preferably a methyl group.

[0098] R in the formula 2 represents a group having a polyoxyalkylene group, preferably a group of formula -X 2 -O-(Y 2 ) n -Z 2 The group represented by (wherein, X 2 represents methylene, Y 2 represents a polyoxyalkylene group, Z 2 represents a hydrogen atom, an alkyl group or an acyl group, and n represents an integer from 2 to 100).

[0099] As X 2 , vinyl, propenyl, butenyl can be mentioned.

[0100] As Y 2 , oxyethylene group and oxypropylene group can be mentioned.

[0101] As Z 2 The alkyl group or acyl group in , for example, methyl group and acetyl group.

[0102] The oxyalkylene groups contained in the polyoxyalkylene-modified dimethylsiloxane may be composed of only one type of oxyalkylene group or may be composed of two or more types of oxyalkylene groups. In the latter case, the different types of oxyalkylene groups may be linked randomly or in blocks.

[0103] The polymerization degree of the oxyalkylene groups in the polyoxyalkylene-modified polydimethylsiloxane (the number of repeating units of the oxyalkylene groups) is preferably 2 or more. The polymerization degree is preferably 100 or less, more preferably 50 or less, and even more preferably 20 or less.

[0104] The degree of polymerization of dimethylsiloxane in the polyoxyalkylene-modified polydimethylsiloxane (the number of repeating dimethylsiloxane units) is preferably 2 or greater. This degree of polymerization is preferably 100 or less, more preferably 50 or less, and even more preferably 25 or less. In this case, the dispersion liquid tends to have excellent dispersion stability, handleability, and long-term storage properties.

[0105] Specific examples of polyoxyalkylene-modified polydimethylsiloxane include "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", and "BYK-3456" (manufactured by Big Chemie Japan Co., Ltd.), "KF-6011", and "KF-6043".

[0106] The liquid dispersion medium of the present invention is preferably a polar compound that is liquid at 25° C. under atmospheric pressure, and more preferably at least one selected from the group consisting of water, amides, ketones, and esters.

[0107] The boiling point of the liquid dispersion medium is preferably in the range of 50-240°C.

[0108] The liquid dispersion medium may be used alone or in combination of two or more.

[0109] When such a liquid dispersion medium is used, the present dispersion tends to be excellent in dispersion stability, handleability, and long-term storage properties.

[0110] Specific examples of the liquid dispersion medium include water, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, cyclopentanone, butyl acetate, methyl isopropyl ketone, and methyl ethyl ketone.

[0111] In addition, the liquid dispersion medium may contain other solvents.

[0112] Examples of other solvents include aliphatic or aromatic hydrocarbons such as toluene; glycols; glycol ethers such as glycol monoalkyl ether and glycol monoaryl ether; and glycol acetates such as glycol monoalkyl ether acetate and glycol monoaryl ether acetate.

[0113] The liquid dispersion medium preferably contains water. The water content in the liquid dispersion medium is preferably 80% by mass or more, more preferably 100% by mass.

[0114] When the liquid dispersion medium contains water, the pH of the present dispersion is preferably 6 to 12, more preferably 7 to 11. In this case, the long-term storage properties of the present dispersion tend to be excellent.

[0115] In order to adjust the pH of the present dispersion, the present dispersion may contain ammonia or amines.

[0116] Specific examples of amines include alkanolamines such as ethanolamine, secondary amines such as dimethylamine and diethylamine, tertiary amines such as triethylamine and N-methylmorpholine, and quaternary ammonium hydroxides such as tetramethylammonium hydroxide.

[0117] The content of polymer F in this dispersion is preferably 5% by mass or greater, more preferably 10% by mass or greater, and even more preferably 25% by mass or greater. The content of polymer F is preferably 70% by mass or less, more preferably 50% by mass or less. In this case, the dispersion exhibits excellent dispersion stability, operability, and long-term storage properties, and a fired product of any thickness can be easily produced from the dispersion.

[0118] The content of polyoxyalkylene-modified polydimethylsiloxane in this dispersion is preferably 30% by mass or less, more preferably 15% by mass or less. The content of polyoxyalkylene-modified polydimethylsiloxane is preferably 0.1% by mass or more, more preferably 1% by mass or more. In this case, the dispersion tends to have excellent dispersion stability, handleability, and long-term storage properties, and the fired product obtained from this dispersion tends to have excellent physical properties such as electrical properties and surface smoothness.

[0119] The content of the liquid dispersion medium of the present invention is preferably 30 to 90% by mass, more preferably 50 to 80% by mass.

[0120] The viscosity of this dispersion is preferably 5 mPa·s or greater, more preferably 10 mPa·s or greater. The viscosity of this dispersion is preferably 2000 mPa·s or less, more preferably 1000 mPa·s or less, further preferably less than 400 mPa·s, and particularly preferably less than 300 mPa·s. In this case, the coating properties of this dispersion are excellent, and a fired product (polymer layer, etc.) of any thickness can be easily formed. In addition, the physical properties of the F polymer are easily exhibited in the fired product obtained from this dispersion within this viscosity range.

[0121] The thixotropic ratio of the present dispersion is preferably 1.0 or greater. The thixotropic ratio of the present dispersion is preferably 3.0 or less, and more preferably 2.0 or less. In this case, the coating and uniformity of the present dispersion are excellent, and a denser fired product (polymer layer, etc.) can be easily formed.

[0122] The present dispersion may further contain another resin (polymer) different from the polymer F. When the present dispersion contains another resin, the dispersion stability, handleability, and long-term storage properties are also likely to be excellent.

[0123] The other resins may be thermosetting resins or thermoplastic resins.

[0124] Examples of other resins include epoxy resins, maleimide resins, polyurethane resins, elastomers, polyimides, polyamic acids, polyamideimides, polyphenylene ethers, polyphenylene ethers, liquid crystal polyesters, and fluorine-containing polymers other than F polymers.

[0125] As the other resin, an aromatic polymer is preferred. When the present dispersion contains an aromatic polymer, the burned product formed from the present dispersion tends to have excellent adhesiveness, low linear expansion properties, and UV absorbency.

[0126] The aromatic polymer is preferably an aromatic elastomer such as aromatic polyimide, aromatic polyamideimide, aromatic maleimide, or styrene elastomer, or aromatic polyamic acid, more preferably an aromatic elastomer such as aromatic polyimide, aromatic polyamideimide, a precursor of aromatic polyamideimide, aromatic maleimide, polyphenylene ether, or styrene elastomer, and even more preferably aromatic polyimide or aromatic polyamic acid.

[0127] Aromatic polyimides can be either thermoplastic or thermosetting.

[0128] Thermoplastic polyimide refers to a polyimide in which imidization has been completed and no further imidization reaction will occur.

[0129] Specific examples of aromatic polyimides include the “Neopulim (registered trademark)” series (manufactured by Mitsubishi Gas Chemical Corporation), the “SPIXAREA (registered trademark)” series (manufactured by Somaron Corporation), the “Q-PILON (registered trademark)” series (manufactured by PI Technical Research Institute), the “WINGO” series (manufactured by WINGO Technology Co., Ltd.), the “TOHMIDE (registered trademark)” series (manufactured by T&KTOKA Co., Ltd.), the “KPI-MX” series (manufactured by Kawamura Industrial Co., Ltd.), and the “UPIA (registered trademark)-AT” series (manufactured by Ube Industries, Ltd.).

[0130] Specific examples of aromatic polyamide-imide and the precursor of aromatic polyamide-imide include "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials Co., Ltd.).

[0131] Examples of the styrene elastomer include styrene-butadiene copolymers, hydrogenated styrene-butadiene copolymers, hydrogenated styrene-isoprene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, and hydrogenated styrene-isoprene-styrene block copolymers.

[0132] The present dispersion may further contain an inorganic filler. In this case, the fired product produced from the present dispersion tends to have excellent electrical properties and low linear expansion properties.

[0133] The inorganic filler is preferably a nitride filler or an inorganic oxide filler, more preferably a boron nitride filler, a beryllium oxide filler such as a beryllium oxide filler, a silica filler, wollastonite filler, a talc filler or a metal oxide filler such as a cerium oxide filler, an aluminum oxide filler, a magnesium oxide filler, a zinc oxide filler, a titanium oxide filler, and more preferably a silica filler.

[0134] The inorganic filler preferably has at least a portion of its surface treated with a silane coupling agent (3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane or 3-isocyanatepropyltriethoxysilane, etc.).

[0135] The inorganic filler preferably has a D50 of 20 μm or less, more preferably 10 μm or less, and preferably 0.01 μm or more, more preferably 0.1 μm or more.

[0136] The shape of the inorganic filler may be any of granular, needle-like (fibrous), and plate-like. Specific shapes of the inorganic filler include spherical, flaky, lamellar, leaf-like, almond-like, columnar, cockscomb-like, equiaxed, leaf-like, mica-like, massive, flat, wedge-like, rosette-like, grid-like, and rectangular prism-like.

[0137] The inorganic filler may be used alone or in combination of two or more.

[0138] Specific examples of favorable inorganic fillers include silica fillers (such as the "Admafin" (registered trademark) series manufactured by Yaduma Tech Co., Ltd.), zinc oxide fillers surface-treated with esters such as propylene glycol dicaprate (such as the "FINEX" (registered trademark) series manufactured by Sakai Chemical Industry Co., Ltd.), spherical fused silica fillers (such as the "SFP" (registered trademark) series manufactured by Denka Co., Ltd.), and polyols. Zinc oxide fillers coated with inorganic substances (such as the "TIPAQUE" (registered trademark) series manufactured by Ishihara Sangyo Co., Ltd.), rutile titanium oxide fillers surface-treated with alkylsilanes (such as the "JMT" (registered trademark) series manufactured by Teika Co., Ltd.), hollow silica fillers (such as the "E-SPHERES" series manufactured by Pacific Cement Co., Ltd., and the "SILINA" series manufactured by Nippon Steel Mining Co., Ltd.) (such as the "Silnacks" series manufactured by Emerson & Cuming, the "Eccospheres" series manufactured by Emerson & Cuming, etc.), talc fillers (such as the "SG" series manufactured by Nippon Talc Co., Ltd.), block talc fillers (such as the "BST" series manufactured by Nippon Talc Co., Ltd.), and boron nitride fillers (such as the "UHP" series manufactured by Showa Denko K.K. and the "Denka Boron Nitride" series ("GP" and "HGP" grades manufactured by Denka Co., Ltd.).

[0139] In addition to the above-mentioned components, the present dispersion may also contain additives such as a thixotropy-imparting agent, a defoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a colorant, a conductive agent, a release agent, a viscosity modifier, a flame retardant, and an organic filler. The present dispersion preferably does not contain a fluorinated surfactant. Due to the aforementioned mechanism of action, even if the present dispersion does not contain a fluorinated surfactant, its dispersion stability is still likely to be excellent.

[0140] In the case where the present dispersion contains an aromatic polymer, the content of the aromatic polymer in the present dispersion is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass.

[0141] In the case where the present dispersion contains an inorganic filler, the content of the inorganic filler in the present dispersion is preferably 1 to 50% by mass, more preferably 5 to 40% by mass.

[0142] As a favorable form of this dispersion, a form that further comprises at least one nonionic surfactant selected from ester surfactants, ether surfactants, ester ether surfactants, alkanolamide surfactants, alkyl glycosides and higher alcohols (hereinafter also referred to as "other surfactants") can be cited. In this case, the dispersion stability of this dispersion during long-term storage is easily further improved. The reason for this is not yet clear, but it is believed that this is due to the relative improvement of the dispersing effect of other highly stable surfactants on the F powder over time. In particular, in this dispersion in which the liquid dispersion medium is water, this mechanism of action is easily enhanced.

[0143] When the present dispersion contains another surfactant, the content of the other surfactant in the present dispersion is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass. In this case, the ratio of the content of the other surfactant to the content of the polyoxyalkylene-modified polydimethylsiloxane in the present dispersion is preferably 0.1 to 10.

[0144] The other surfactant is preferably an ether-type surfactant or an ester-ether-type surfactant, more preferably a glycol monoalkyl ether, a glycol monoaryl ether, a glycol monoalkyl ether acetate or a glycol monoaryl ether acetate, further preferably a glycol monoalkyl ether.

[0145] The glycol monoalkyl ether is preferably polyethylene glycol monoalkyl ether. The number of ethylene oxide units (-OCH2CH2-) contained in the polyethylene glycol is preferably 1 to 10, and the monoalkyl ether group is preferably highly branched.

[0146] Specific examples of other surfactants include polyethylene glycol decyl ether, polyethylene glycol undecyl ether, polyethylene glycol lauryl ether, polyethylene glycol tridecyl ether, polyethylene glycol tetradecyl ether, triethylene glycol monomethyl ether, polyethylene glycol trimethyl nonyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monomethyl ether, tripropylene glycol monobutyl ether, propylene glycol monophenyl ether, diethylene glycol monoethyl ether acetate, or diethylene glycol monobutyl ether acetate.

[0147] Specific examples of other favorable surfactants include the "Tergitol" series (such as "Tergitol TMN-100X" manufactured by The Dow Chemical Company), "Lutensol T08", "Lutensol XL70", "Lutensol XL80", "Lutensol XL90", "Lutensol XP80", and "Lutensol M5" (all manufactured by BASF Corporation), "Newcol 1305", "Newcol 1308FA", and "Newcol 1310" (all manufactured by Nippon Emulsifier Co., Ltd.), and "LEOCOL TDN-90-80" and "LEOCOL SC-90" (all manufactured by Lion Specialty Chemicals Co., Ltd.).

[0148] The present invention further provides a powder dispersion (hereinafter also referred to as the "second dispersion") comprising a tetrafluoroethylene polymer powder, a polyoxyalkylene-modified polydimethylsiloxane comprising dimethylsiloxane units in the main chain and having oxyalkylene groups in the side chains, or a polyoxyalkylene-modified polydimethylsiloxane comprising dimethylsiloxane units in the main chain and having oxyalkylene groups at the main chain terminals, and a liquid dispersion medium comprising at least water, wherein the dispersion medium has a viscosity of less than 400 mPa·s.

[0149] The respective forms (including favorable ranges) of the F powder and the polyoxyalkylene-modified polydimethylsiloxane in this powder dispersion are the same as those of the present dispersion.

[0150] The liquid dispersion medium containing at least water in the powder dispersion may consist of water alone or may consist of water and another liquid dispersion medium. The other liquid dispersion medium has the same form as that of the present dispersion.

[0151] The various components (including favorable ranges) of this powder dispersion are the same as those of the present dispersion. In particular, the viscosity of this powder dispersion is preferably 5 mPa·s or more and less than 400 mPa·s, and more preferably 10 mPa·s or more and less than 300 mPa·s.

[0152] Preferably, the weight average molecular weight of the polyoxyalkylene-modified polydimethylsiloxane having a main chain comprising dimethylsiloxane units and a side chain having an oxyalkylene group, or the polyoxyalkylene-modified polydimethylsiloxane having a main chain comprising dimethylsiloxane units and a main chain terminal having an oxyalkylene group, is less than 3000, and the HLB value calculated by the Griffin formula is 1-18.

[0153] More favorable ranges of the weight average molecular weight and HLB value are the same as those described above.

[0154] The present dispersion or the second present dispersion can be produced by mixing F powder, the polyoxyalkylene-modified polydimethylsiloxane, a liquid dispersion medium, and, if necessary, other surfactants. Preferably, the dispersion can be produced by mixing F powder with a liquid composition comprising the polyoxyalkylene-modified polydimethylsiloxane, a liquid dispersion medium, and, if necessary, other surfactants.

[0155] When the present dispersion or the second present dispersion contains two or more types of F powders, the present dispersion or the second present dispersion can be produced by mixing a mixture of the two or more types of F powders with a liquid composition containing the polyoxyalkylene-modified polydimethylsiloxane and a liquid dispersion medium. Alternatively, the present dispersion or the second present dispersion can be produced by mixing a liquid composition containing the F powder, the polyoxyalkylene-modified polydimethylsiloxane, a liquid dispersion medium, and, if necessary, other surfactants with a liquid composition containing a different type of F powder and a liquid dispersion medium. The latter method is preferred.

[0156] In the case of the latter method, the liquid composition comprising different kinds of F powders and a liquid dispersion medium may further comprise the polyoxyalkylene-modified polydimethylsiloxane or other surfactants.

[0157] When the present dispersion is applied onto the surface of a substrate and heated to generate a burned product of the F polymer, a composite having the substrate and the burned product of the F polymer can be obtained.

[0158] Specific examples of the composite include a laminate (hereinafter also referred to as the "present laminate") having a substrate and a polymer layer containing an F polymer (hereinafter also referred to as the "F layer"), fibers sized by the F polymer, a prepreg containing fibers sized by the F polymer and a matrix resin, and a fiber-reinforced composite material formed from such a prepreg.

[0159] When the substrate is in the form of a sheet, the present dispersion is applied to the surface of the sheet substrate to form a liquid film, the liquid film is heated to remove the liquid dispersion medium and form a dry film, and the dry film is further heated to calcine the F polymer. This laminate having the F layer on the surface of the sheet substrate can be obtained.

[0160] Examples of sheet-like substrates include metal substrates such as metal foils of copper, nickel, aluminum, titanium, and alloys thereof, heat-resistant resin films, and prepregs that are precursors to fiber-reinforced resin substrates. Furthermore, the heat-resistant resin film refers to a film comprising one or more heat-resistant resins such as polyimide, polyacrylate, polysulfone, polyarylsulfone, polyamide, polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystal polyester, liquid crystal polyesteramide, or F polymer, and may be a single-layer film or a multilayer film. The F polymer contained in the heat-resistant resin film is preferably PTFE, PFA, or FEP.

[0161] The method for applying the present dispersion to the substrate surface may be any method that forms a stable liquid film (i.e., a wet film) composed of the present dispersion on the surface of the sheet-like substrate. Examples thereof include coating, droplet discharge, and dipping methods, with coating being preferred.

[0162] When drying the liquid film, the film is heated at a temperature at which the liquid dispersion medium evaporates, thereby forming a dry film on the surface of the sheet-like substrate. This heating temperature is preferably 50°C or less, and more preferably below the boiling point of the liquid dispersion medium. Specifically, the drying temperature is preferably 70-200°C. Air may be purged during the liquid dispersion medium removal step.

[0163] During drying, the liquid dispersion medium does not need to be completely volatilized, but it only needs to be volatilized to such an extent that the shape of the layer after being maintained is stable and the film can be maintained autonomously.

[0164] The temperature during calcination of the F polymer is preferably 380° C. or lower.

[0165] The heating may be performed under normal pressure or reduced pressure.

[0166] The heating atmosphere may be any of an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, and an inert gas atmosphere such as helium, neon, argon, and nitrogen.

[0167] The heating time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.

[0168] The thickness of the F layer is preferably 0.1 to 150 μm. Specifically, when the sheet-like substrate is a metal foil, the thickness of the F layer is preferably 1 to 30 μm. When the sheet-like substrate is a heat-resistant resin film, the thickness of the F layer is preferably 1 to 150 μm.

[0169] The peel strength between the F layer and the sheet-like substrate is preferably 10 N / cm or greater, more preferably 15 N / cm or greater. The peel strength is preferably 100 N / cm or less. Using this dispersion will not impair the physical properties of the F polymer in the F layer, allowing easy formation of this laminate.

[0170] The present dispersion can be applied to only one surface of a sheet substrate or to both surfaces. The former method yields a sheet substrate and a laminate having an F layer on a single surface thereof, while the latter method yields a sheet substrate and a laminate having an F layer on both surfaces thereof. The latter method is less prone to warping and therefore offers excellent handling properties during processing.

[0171] The present laminate having the F layer on both surfaces of a sheet-like substrate is preferably obtained by immersing the substrate in the present dispersion, applying the present dispersion to both surfaces of the substrate, and then passing the substrate through a firing furnace for heating. Specifically, it is more preferably obtained by immersing the substrate in the present dispersion, then pulling the substrate up from the dispersion while passing the substrate through a firing furnace for heating.

[0172] The direction in which the substrate is pulled up and passed through the firing furnace is preferably with the plumb bob upward. In this case, a smooth F layer is easily formed. After the substrate is pulled up with the plumb bob upward, it can be pulled down with the plumb bob while continuing to heat, or it can be pulled down without heating to obtain the substrate.

[0173] The amount of the present dispersion applied to the substrate can be adjusted by passing the substrate to which the present dispersion adheres through a pair of rollers.

[0174] This laminate can be advantageously produced using an apparatus comprising a dip coater and a firing furnace. Examples of the firing furnace include a vertical firing furnace. Furthermore, examples of such an apparatus include a glass cloth coating apparatus manufactured by Tabata Machinery Industry Co., Ltd.

[0175] Specific examples of the present laminate include a metal foil and a metal-clad laminate having an F layer on at least one surface of the metal foil, a polyimide film, and a multilayer film having F layers on both surfaces of the polyimide film.

[0176] Since the present laminate has an F layer with excellent electrical properties, it is advantageous as a printed circuit board material. Specifically, it can be used as a flexible metal-clad laminate or a rigid metal-clad laminate for the manufacture of printed circuit boards. In particular, it can be advantageously used as a flexible metal-clad laminate for the manufacture of flexible printed circuit boards.

[0177] In the manufacture of such a printed circuit board, an interlayer insulating film, a solder resist, or a cover film can be formed on the transmission circuit. These interlayer insulating films, solder resist, and cover films can be formed using this dispersion.

[0178] Furthermore, the present laminate can be used as a carrier film for forming a ceramic green sheet, a carrier film for forming a secondary battery, a carrier film for forming a solid polymer electrolyte membrane, and a carrier film for forming a catalyst layer of a solid polymer electrolyte membrane.

[0179] The laminate of the F layer and the base material can be used in antenna components, printed circuit boards, aircraft parts, automotive parts, sports equipment, food industry products, heat dissipation components, coatings, cosmetics, and the like. It can also be used as a new printed circuit board material to replace conventional glass epoxy boards in order to prevent temperature rise in printed circuit boards densely mounted with electronic components.

[0180] Specifically, it can be used as an electric wire coating material such as an aircraft wire, an enameled wire coating material for a motor such as an electric vehicle, a separation membrane, an electrode adhesive for a lithium secondary battery or a fuel cell, a sliding member, a tool, a blade for a windmill or wind power generation equipment or an aircraft, an electrical insulating tape, an insulating tape for oil drilling, a material for a printed circuit board, a copy roller, a cover for furniture, an automobile instrument panel, a household appliance, a wear-resistant pad, a wear-resistant strip, a tube lamp, a test socket, a wafer guide, a wear-resistant part of a centrifugal pump, a hydrocarbon chemical and water supply pump, a boiler, a hopper, a pipeline, an oven, a baking mold, a chute, a mold, a toilet, a container coating material, a power device, a transistor, a thyristor, a rectifier, a transformer, a power MOSFET, a CPU, a heat dissipation fin, a metal heat dissipation plate. In addition, as a separation membrane, a precision filtration membrane, an ultrafiltration membrane, a reverse osmosis membrane, an ion exchange membrane, a dialysis membrane, and a gas separation membrane can be listed. Examples of sliding members include load bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, piston washers, pistons, slide switches, gears, cams, belt conveyors, and food conveyor belts. Examples of tools include shovels, files, awls, and saws.

[0181] More specifically, it can be used as a casing for computers or displays, electronic device materials, interior and exterior decoration of automobiles, sealing materials for processing machines or vacuum furnaces for heat treatment under low oxygen conditions, plasma processing equipment, etc., or heat dissipation components within processing units such as sputtering or various dry etching equipment.

[0182] This dispersion can also be used to form a heat-conductive, heat-resistant coating by impregnating and drying the insulation layers of printed wiring boards, thermal interface materials, substrates for power modules, and coils used in power devices such as electric motors. It can also be used to bond ceramic and metal components in automotive engines, impart corrosion resistance to heat exchangers or the fins and tubes that comprise them, and coat the interior and exterior of glass containers. This is particularly advantageous for coatings that impart impact resistance. Examples of glass containers include vials, syringes, syringes with needles, barrel-type syringes, and ampoules.

[0183] Furthermore, the present dispersion can be used as a binder material for electrodes of electrochemical devices including electrodes such as lithium-ion batteries, primary batteries such as lithium batteries, free radical batteries, solar cells, particularly dye-sensitized solar cells, fuel cells, capacitors such as lithium-ion capacitors, hybrid capacitors, and electric double-layer capacitors, various capacitors such as aluminum electrolytic capacitors and tantalum electrolytic capacitors, electrochromic elements, electrochemical conversion elements, and various electrochemical sensors, as well as a coating material for separators and a coating material for positive or negative electrodes. When used as such a coating material, the present dispersion preferably comprises water as the liquid dispersion medium.

[0184] Alternatively, the F powder itself may be used as the coating material. In this case, the F powder may be used alone or in combination with other materials (such as other resins and inorganic fillers that may be included in the present dispersion). In this case, if the F polymer is polymer (1), the D50 of the F powder is preferably 1-8 μm or 10-40 μm.

[0185] Furthermore, this dispersion, further comprising a conductive filler, can be advantageously used in applications requiring electrical conductivity, such as printed electronics. Specifically, it can be used in the manufacture of energized components such as printed circuit boards, sensor electrodes, displays, backplanes, RFID (radio frequency identification), solar power generation, lighting, disposable electronic devices, automotive motors, electromagnetic wave (EMI) shielding covers, and membrane switches.

[0186] In addition, the calcined product obtained by this dispersion liquid comprising conductive filler can be used as an adhesive for the bonding of electronic components such as IC chips, resistors, capacitors, etc. installed on substrates, the bonding of circuit substrates and heat release plates, and the bonding of LED chips to substrates in semiconductor elements, high-density substrates, and module components. Further, the calcined product can also be used as a conductive bonding material (as a substitute for solder bonding) between circuit wiring and electronic components in the installation process of electronic components. In addition, it can also be used for the adhesive between ceramic components and metal components in vehicle-mounted engines. In addition, the calcined product can also be used for the purposes described in International Publication No. 2016 / 017801

[0149] .

[0187] When the substrate is a fiber, by applying the present dispersion to the fiber surface and evaporating the liquid dispersion medium, a sized fiber with the F polymer attached to the surface can be obtained.

[0188] The F polymer attached to the fiber surface is preferably a burnt product of the F polymer. Fibers with the burnt product of the F polymer attached to the surface and sized can be obtained by evaporating the liquid dispersion medium from the fiber to which the present dispersion has been applied, and then heating the fiber to burn the F polymer.

[0189] The heating for evaporating the liquid dispersion medium and calcining the F polymer may be the same as the heating for forming the above-mentioned F layer.

[0190] As fibers, there can be listed glass fibers such as E glass, D glass, L glass, S glass, T glass, Q glass, UN glass, NE glass, and spherical glass; organic fibers such as aramid fibers, polyolefin fibers, modified polyphenylene ether fibers, vinylon fibers, rayon fibers, polyester fibers, and natural fibers; boron fibers, carbon fibers, and metal fibers, preferably carbon fibers.

[0191] Examples of the carbon fiber include pitch-based carbon fibers, rayon-based carbon fibers, polyacrylonitrile (PAN)-based carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers, with acrylonitrile (PAN)-based carbon fibers being preferred.

[0192] The shape of the fibers may be chopped strands, cladding mats, bundles, or any of these, such as felts, woven fabrics, and nonwoven fabrics. Fiber length and cross-sectional shape are also not particularly limited.

[0193] The fibers after sizing treatment can be used as fiber bundles or as sheet-shaped reinforcing fiber materials. The fibers after sizing treatment can be used as continuous fibers or discontinuous fibers.

[0194] Fibers sized with this dispersion have excellent adhesion to the matrix resin and high impregnation of the matrix resin into the fiber bundles. Therefore, prepregs and fiber-reinforced composite materials with excellent mechanical properties can be easily obtained from such fibers.

[0195] Prepregs can be produced by impregnating sizing-treated fibers with a matrix resin or a matrix resin composition and drying to semi-cure the fibers.

[0196] As the matrix resin, polysulfone, polyphenylsulfone, polyethersulfone, aromatic polyetherketone, polyetherimide, polyphenylene sulfide, and liquid crystal polyester are preferable.

[0197] If the prepregs are stacked and the matrix resin is heated while applying pressure to the stack, a fiber-reinforced composite material can be obtained. In addition, the F polymer can be fired when the matrix resin is heated.

[0198] The fiber-reinforced composite material may be laminated with other substrates. Examples of other substrates include metal substrates, heat-resistant resin films, and prepregs that are precursors of fiber-reinforced resin sheets.

[0199] Such fiber-reinforced composite materials can be advantageously used in applications requiring strength, wear resistance, chemical resistance, flame retardancy, and low vibration. Examples include outer packaging, inner packaging, structural members, sliding parts represented by gears or bearings, insulating parts, pressure ropes, sports equipment such as rackets or bats, industrial machinery, robots, parts of medical equipment, oil drilling equipment, oil pipelines, hydrogen storage tanks, hydrogen storage tank pressure vessels, blades for wind turbines, liquid nitrogen storage tanks, and inner and outer packaging for rotating parts of motors and compressors, etc.

[0200] When the second dispersion is applied onto the surface of a substrate and heated to generate a burned product of the F polymer, a composite having the substrate and the burned product of the F polymer can be obtained.

[0201] Examples of the composite include the same ones as those obtained from the present dispersion, and the production method and uses thereof are also the same as those of the composite obtained from the present dispersion.

[0202] The powder dispersion and the composite production method of the present invention have been described above, but the present invention is not limited to the configurations of the above-described embodiments.

[0203] For example, the powder dispersion of the present invention may be added to the configuration of the above-mentioned embodiment, or may be replaced with any other structure that exhibits the same function.

[0204] Furthermore, the method for producing the composite of the present invention may add steps for other arbitrary purposes to the configuration of the above-mentioned embodiment, or may replace the steps with arbitrary steps that exhibit the same function.

[0205] Example

[0206] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0207] 1. Preparation of Ingredients

[0208] [powder]

[0209] Powder 1: A powder composed of polymer 1 (melting temperature: 300°C) containing 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE units, NAH units, and PPVE units, in that order (D50: 2.1 μm)

[0210] Powder 2: A powder composed of polymer 2 (melting temperature 305°C) containing 97.5 mol% of TFE units and 2.5 mol% of PPVE units in that order (D50: 1.8 μm)

[0211] Powder 3: Powder 3 composed of non-thermofusible PTFE (D50: 0.3 μm)

[0212] In addition, for every 1×10 6 In terms of the carbonyl-containing groups per main chain carbon number, polymer 1 has 1000 and polymer 2 has 40.

[0213] [Surfactant]

[0214] Surfactant 1: Polyoxyalkylene-modified polydimethylsiloxane having a dimethylsiloxane unit in the main chain and oxyethylene groups in the side chains (weight average molecular weight: 1600, dispersity: 1.5, HLB value: 13, static surface tension: 25 mN / m, dynamic surface tension of a 0.1% by mass aqueous solution: 30 mN / m)

[0215] Surfactant 2: Polyoxyalkylene-modified polydimethylsiloxane having a dimethylsiloxane unit in the main chain and oxyethylene groups at the main chain ends (weight average molecular weight: 1000, dispersity: 1.1, HLB value: 14, static surface tension: 25 mN / m, dynamic surface tension: 30 mN / m)

[0216] Surfactant 3: Polyoxyalkylene-modified polydimethylsiloxane (weight average molecular weight: 4000, dispersion degree 2.1, HLB value: 16, static surface tension: 26 mN / m, dynamic surface tension: 35 mN / m)

[0217] Surfactant 4: Polyoxyalkylene-containing polyorganosiloxane (weight average molecular weight 1800, dispersity 1.9, HLB value: 8, static surface tension: 30 mN / m, dynamic surface tension: 42 mN / m)

[0218] Surfactant 5: Polyoxyalkylene-containing polyorganosiloxane (weight average molecular weight 1700, dispersity 1.8, HLB value: 19, static surface tension: 27 mN / m, dynamic surface tension: 36 mN / m)

[0219] Surfactant 6: Polyethylene glycol trimethyl nonyl ether

[0220] Surfactants 4 and 5 are polyoxyalkylene group-containing polyorganosiloxanes, which are different from polyoxyalkylene-modified polydimethylsiloxanes. Surfactants 1 to 6 are all nonionic compounds.

[0221] [Dispersion]

[0222] Dispersion 1: PTFE aqueous dispersion containing 60% by mass of powder 3 ("AD-911E" manufactured by AGC Corporation)

[0223] 2. Example of Preparation of Powder Dispersion

[0224] (Example 1)

[0225] First, Powder 1, Surfactant 1, and ammonia water were placed in a tank, followed by zirconia balls. The tank was then rolled at 150 rpm for 1 hour to produce Composition 1. Composition 1 and Dispersion 1 were placed in another tank, followed by zirconia balls. The tank was then rotated at 150 rpm for 1 hour to produce Powder Dispersion 1, which contained Powder 1 (5 parts by mass), Powder 3 (45 parts by mass), Surfactant 1 (0.25 parts by mass), and ammonia water (47.5 parts by mass). The mixture had a viscosity of 20 mPa·s and a pH of 10.

[0226] (Example 2-6)

[0227] Powder dispersions 2-6 were obtained in the same manner as in Example 1, except that the types of powder and surfactant were changed to those shown in Table 1 below. In Table 1, "∘" in the ammonia column indicates that the powder dispersion contains ammonia, and "-" indicates that the powder dispersion does not contain ammonia.

[0228] (Example 7)

[0229] First, powder 1, surfactant 1, and ammonia water were placed in a tank, followed by zirconia balls. The tank was then rotated at 150 rpm for 1 hour to obtain powder dispersion 7 containing powder 1 (40 parts by mass), surfactant 1 (2 parts by mass), and ammonia water (58 parts by mass) with a viscosity of 30 mPa·s and a pH of 10.

[0230] (Examples 8 and 9)

[0231] Powder dispersions 8 and 9 were obtained in the same manner as in Example 7 except that the type of surfactant was changed to that shown in Table 1 below.

[0232] (Example 10)

[0233] A powder dispersion 10 was obtained in the same manner as in Example 7 except that the type of surfactant was changed to that shown in Table 1 below and water was used instead of aqueous ammonia.

[0234] Furthermore, the degree of change in hue during long-term storage for Powder Dispersions 1 to 3 was smaller than that for Powder Dispersions 4 to 6. The degree of change in hue during long-term storage for Powder Dispersions 7 and 8 was smaller than that for Powder Dispersions 9 and 10.

[0235] [Table 1]

[0236]

[0237] 3. Example of manufacturing a laminate (composite)

[0238] Powder dispersion 1 was applied to the surface of a long copper foil (18 μm thick) using a bar coater to form a liquid film. The copper foil with the liquid film was then passed through a drying oven at 120°C for 5 minutes to dry it by heating, yielding a dry film. The dry film was then heated in a nitrogen oven at 380°C for 3 minutes. This produced a laminate 1 comprising a copper foil and, on its surface, a polymer layer (5 μm thick) comprising a melted and fired product of powder 1 and a fired product of powder 3.

[0239] Laminated bodies 2-10 were respectively produced in the same manner as for the laminated body 1 except that the powder dispersion 1 was changed to the powder dispersions 2-10.

[0240] 4. Evaluation

[0241] 4-1. Dispersion stability of powder dispersion

[0242] Each powder dispersion was stored in a container at 25°C for 24 hours, and then its dispersibility was visually confirmed and its dispersion stability was evaluated according to the following criteria. The same criteria were used to evaluate the dispersion stability after 60 days of storage.

[0243] [Evaluation Criteria]

[0244] ○: No agglutinate was detected.

[0245] △: Fine aggregates are observed on the side of the container. Gently stirring will redisperse the mixture evenly.

[0246] ×: Agglomerates were also observed at the bottom of the container. When shearing and stirring were applied, the mixture was evenly redispersed.

[0247] 4-2. Defoaming properties of powder dispersions

[0248] When preparing (producing) each powder dispersion, the time until foaming disappeared was confirmed, and the defoaming property was evaluated according to the following criteria.

[0249] [Evaluation Criteria]

[0250] ○: Less than 3 hours

[0251] △: 3 hours or more and less than 6 hours

[0252] ×: More than 6 hours

[0253] 4-3. Surface smoothness of laminate

[0254] Each laminate was irradiated with light from the polymer layer side, and visually observed from obliquely above the polymer layer to evaluate surface smoothness according to the following criteria.

[0255] [Evaluation Criteria]

[0256] ○: The surface of the polymer layer is smooth as a whole.

[0257] Δ: A pockmark pattern was observed in a portion of the polymer layer.

[0258] ×: A pockmark pattern was observed throughout the entire polymer layer.

[0259] The respective results are shown in Table 2 below together with the physical properties (viscosity, pH) of the powder dispersion.

[0260] [Table 2]

[0261]

[0262] (Example 11)

[0263] First, powder 1, surfactant 1, surfactant 6, and ammonia water were added to a tank, followed by zirconia balls. The tank was then rotated at 150 rpm for 1 hour to obtain a powder dispersion 11 containing 40 parts by mass of powder 1, 2 parts by mass of surfactant 1, 2 parts by mass of surfactant 6, and 56 parts by mass of ammonia water, with a viscosity of 30 mPa·s and a pH of 10. Laminated body 11 was produced in the same manner as laminated body 1, except that powder dispersion 1 was replaced with powder dispersion 11. Evaluation results for dispersion stability, defoaming properties, and surface smoothness of laminated body 11 were all "0."

[0264] (Example 12)

[0265] The same procedures as in Example 11 were followed to obtain a powder dispersion 12 having a viscosity of 33 mPa·s and a pH of 10, comprising Powder 1 (40 parts by mass), Surfactant 1 (0.5 parts by mass), Surfactant 6 (3.5 parts by mass), and aqueous ammonia (56 parts by mass). Laminated body 12 was produced in the same manner as laminated body 1, except that Powder Dispersion 1 was replaced with Powder Dispersion 12. The evaluation results for the dispersion stability, defoaming properties, and surface smoothness of Powder Dispersion 12 were all "0."

[0266] Furthermore, the dispersion stabilities of the powder dispersions 7, 11, and 12 stored at 25° C. for 60 days were “×”, “◯”, and “◯”, respectively.

[0267] Possibility of industrial application

[0268] The powder dispersion of the present invention exhibits excellent dispersion stability, handling properties, and long-term storage properties. It can be used to produce composite materials such as laminates of fired products exhibiting properties based on the F polymer, sized fibers, prepregs, and impregnated fiber-reinforced composite materials. The composite of the present invention can be used in antenna components, printed circuit boards, aircraft components, automotive components, sports equipment, food industry products, coatings, and cosmetics. Specifically, it can be used as wire coating materials for aircraft wires, separation membranes such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, and gas separation membranes, electrode binders for lithium secondary batteries and fuel cells, load bearings, sliding shafts, valves, bearings, gears, cams, sliding members such as conveyor belts and food conveyor belts, tools such as shovels, files, awls, and saws, electrical insulating tapes, oil drilling tapes, printed circuit board materials, copy rollers, covers for furniture, automobile dashboards, and household appliances, boilers, hoppers, pipes, ovens, baking molds, chutes, molds, toilets, and container coverings.

Claims

1. A powder dispersion comprising 5-70% by mass of a tetrafluoroethylene polymer powder, a liquid dispersion medium, 0.1-30% by mass of a polyoxyalkylene-modified polydimethylsiloxane having a weight-average molecular weight of 3000 or less, an HLB value calculated by the Griffin equation of 10 or more and 15 or less, and a static surface tension of 20 mN / m or more and 28 mN / m or less, and 0.1-15% by mass of an ether-type surfactant, excluding a fluorine-based surfactant.

2. The powder dispersion according to claim 1, wherein The dynamic surface tension of the polyoxyalkylene-modified polydimethylsiloxane is below 40 mN / m.

3. The powder dispersion according to claim 1 or 2, wherein The molecular weight dispersity of the polyoxyalkylene-modified polydimethylsiloxane is less than 2.

0.

4. The powder dispersion according to claim 1, wherein The polymerization degree of the oxyalkylene group in the polyoxyalkylene-modified polydimethylsiloxane is 2-100, and the polymerization degree of the dimethylsiloxane is 2-100.

5. The powder dispersion according to claim 1, wherein The polyoxyalkylene-modified polydimethylsiloxane includes a dimethylsiloxane unit in the main chain and an oxyalkylene group in the side chain.

6. The powder dispersion according to claim 1, wherein The polyoxyalkylene-modified polydimethylsiloxane includes a dimethylsiloxane unit in the main chain and has an oxyalkylene group at the end of the main chain.

7. The powder dispersion according to claim 1, wherein The tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer containing perfluoro(alkyl vinyl ether)-based units, containing 1 to 5 mol % of perfluoro(alkyl vinyl ether)-based units relative to all units, and having a melting temperature of 260 to 320°C.

8. The powder dispersion according to claim 1, wherein The powder contains a first powder of polytetrafluoroethylene and a second powder of a tetrafluoroethylene-based polymer containing units based on perfluoro(alkyl vinyl ether) and containing 1-5 mol% of units based on perfluoro(alkyl vinyl ether) relative to all units and having a melting temperature of 260-320°C, wherein the proportion of the second powder in the total of the first powder and the second powder is less than 25% by mass.

9. The powder dispersion according to claim 1, wherein The liquid dispersion medium contains water.

10. The powder dispersion according to claim 9, wherein The pH of the powder dispersion is 6-12. A method for producing a composite, comprising applying the powder dispersion according to any one of claims 1 to 10 onto a surface of a substrate and heating the substrate to produce a burned product of the tetrafluoroethylene polymer, thereby obtaining a composite comprising the substrate and the burned product.

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