Sizing agents, sizing-treated fibers, prepregs, and dispersions

Abstract

Provides a specific sizing agent, a fiber sizing-treated with the same, and a prepreg that can suppress foaming during heat molding, thereby forming a molded article with excellent appearance such as smoothness and excellent adhesion and water resistance when formed into a laminate, and a dispersion liquid containing a tetrafluoroethylene-based polymer powder and having excellent dispersion stability even when the amount of surfactant is reduced. A sizing agent containing powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 0.1 to 200 μm, a sizing-treated fiber and a prepreg comprising such fiber and a matrix resin, and a dispersion comprising powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 10 to 100 μm, a surfactant, and a liquid dispersion medium, wherein the content of the surfactant is 0.01 or less per 1 part by mass of the heat-meltable tetrafluoroethylene-based polymer powder.

Description

Technology Field

[0001] The present invention relates to a sizing agent comprising a tetrafluoroethylene-based polymer, a sizing-treated fiber, a prepreg, and a dispersion containing a powder of a tetrafluoroethylene-based polymer. Background Technology

[0002] Fiber-reinforced plastics have excellent lightness and durability, and as reinforcing fibers, inorganic fibers such as glass fibers, carbon fibers, boron fibers, and metal fibers, and organic fibers such as aramid fibers, xylon fibers (poly(paraphenylenebenzobisoxazole)), and polyethylene fibers, which have high impact resistance, are used. In particular, because carbon fibers have excellent mechanical properties, carbon fiber reinforced composite materials, in which a matrix resin is reinforced with carbon fibers, are widely used as composite materials to replace metals in general industrial fields, including aircraft components, spacecraft components, automobile components, and ship components, as well as sports applications such as golf shafts and fishing rods, office equipment applications, and computer applications (IC trays, laptop computer casings (housings), etc.).

[0003] Various sizing agents are being considered for the purpose of improving the strength of composite materials by increasing the affinity between the matrix resin and reinforcing fibers to enhance interfacial adhesion, or for the purpose of coating fibers to facilitate handling by suppressing damage. Thermosetting resins such as phenolic resin, melamine resin, bismaleimide resin, unsaturated polyester resin, and epoxy resin are used as sizing agents, and the main component is generally epoxy resin.

[0004] Patent Document 1 discloses a prepreg formed by impregnating a carbon fiber, to which a sizing agent comprising an aliphatic epoxy compound and an aromatic epoxy compound has been attached, with a specific epoxy resin composition as a matrix resin. Patent Document 2 discloses a carbon fiber coated with a sizing agent comprising a polymer having one of an ester bond, a urethane bond, or a carbonate bond within the main chain bond, and discloses that a composite material with excellent mechanical properties can be obtained from such carbon fiber.

[0005] In addition, tetrafluoroethylene-based polymers have low surface energy and tend to aggregate easily, so dispersion stability is likely to be a problem in their dispersions.

[0006] Patent Document 3 discloses a water dispersion containing powder of a tetrafluoroethylene-based polymer.

[0007] Typically, dispersions contain surfactants to enhance the dispersion stability of tetrafluoroethylene-based polymer powders. However, even after the dispersion is applied to and dried on a substrate, surfactants may remain on the substrate surface, causing surface roughness and deteriorating the appearance. Additionally, the presence of surfactants on the substrate surface may lead to a decrease in the electrical properties of the molded product or its adhesion to other substrates. Prior art literature

[0008] Japanese Published Patent Application No. 2014-40566, Japanese Published Patent Application No. 2020-23770, Japanese Published Patent Application No. 2019-52211 The problem to be solved

[0009] When molding fiber-reinforced composite materials containing a super heat-resistant resin, such as a super engineering plastic, as a matrix resin, the molding temperature becomes higher than in the past. In such cases, the sizing agent described in Patent Documents 1 and 2 undergoes thermal decomposition during heat molding to produce volatile components and causes foaming within the molded product, which has a problem in that it affects the appearance, such as the smoothness of the resulting molded product, and the adhesion peel strength.

[0010] The inventors have discovered, through careful examination, that a sizing agent containing a heat-meltable tetrafluoroethylene-based polymer of a specific particle size has excellent interfacial adhesion with a superheat-resistant resin, and that when such a sizing agent is preferably dispersed in a liquid dispersion medium and placed on a fiber, foaming during heat molding can be suppressed due to the heat resistance of the tetrafluoroethylene-based polymer, thereby enabling the formation of a molded article with excellent appearance, such as smoothness. Furthermore, they have discovered that such a molded article has particularly excellent adhesion and water resistance when formed into a laminate.

[0011] The inventors have discovered that if a powder of a tetrafluoroethylene-based polymer with an average particle size within a predetermined range is included, a dispersion with excellent dispersion stability can be obtained even when the amount of surfactant is reduced, and that such a dispersion is useful as a sizing agent, and thus have reached the completion of the present invention.

[0012] The present invention aims to provide a dispersion comprising a sizing agent that suppresses foaming upon heating, a sizing-treated fiber, a prepreg, a powder of a tetrafluoroethylene-based polymer with excellent dispersion stability, and a small amount of surfactant. means of solving the problem

[0013] The present invention has the following aspects.

[0014] <1> A sizing agent containing powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 0.1 to 200 μm.

[0015] <2> A sizing agent of <1> having a melting temperature of the tetrafluoroethylene-based polymer of the above, which is 280 to 325 ℃.

[0016] <3> A sizing agent of <1> or <2>, wherein the 5% weight reduction temperature of the tetrafluoroethylene-based polymer is 360°C or higher.

[0017] <4> A sizing agent of any one of <1> to <3>, wherein the above tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a polar functional group and a perfluoro(alkyl vinyl ether)-based unit, or a tetrafluoroethylene-based polymer having 2.0 to 5.0 mol% of a perfluoro(alkyl vinyl ether)-based unit relative to the total unit and not having a polar functional group.

[0018] <5> The tetrafluoroethylene-based polymer having the above polar functional group is a tetrafluoroethylene-based polymer having carbonyl group-containing groups, wherein the number of carbonyl group-containing groups is 1 × 10 Cs per carbon atom of the main chain 6 Sizing agent of <4>, 10 to 5000 individuals per unit.

[0019] <6> A sizing agent of any one of <1> to <5>, comprising a dispersion containing a powder of the above tetrafluoroethylene-based polymer and a liquid dispersion medium.

[0020] <7> A sizing agent of <6> comprising a powder of the tetrafluoroethylene-based polymer having an average particle size of 10 to 100 μm, a surfactant, and a liquid dispersion medium, wherein the content of the surfactant is 0.01 parts by mass or less per 1 part by mass of the powder of the tetrafluoroethylene-based polymer.

[0021] <8> A sizing-treated fiber with a heat-meltable tetrafluoroethylene-based polymer attached to the surface.

[0022] <9> A sizing-treated fiber of <8>, wherein the amount of the tetrafluoroethylene-based polymer attached is 0.1 to 10 parts by mass per 100 parts by mass of the fiber.

[0023] A prepreg containing a sized fiber as described in <10>, <8>, or <9>, and a matrix resin.

[0024] <11> A dispersion comprising a powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 10 to 100 μm, a surfactant, and a liquid dispersion medium, wherein the content of the surfactant is 0.01 parts by mass or less per 1 part by mass of the tetrafluoroethylene-based polymer powder.

[0025] <12> A dispersion of <11> having a surface tension of the above surfactant of 28 mN / m or less.

[0026] <13> A dispersion of <11> or <12> in which the above surfactant is a silicone-based surfactant, a fluorine-based surfactant, a glycol-based surfactant, or an alkylamide ether-based surfactant.

[0027] <14> A dispersion of any one of <11> to <13>, wherein the content of the tetrafluoroethylene-based polymer is 25 to 60 parts by mass per 100 parts by mass of the liquid dispersion medium.

[0028] A sizing agent composed of a dispersion of any of <15>, <11>, to <14>. Effects of the invention

[0029] The prepreg containing fibers treated with the sizing agent of the present invention and a matrix resin exhibits excellent adhesion between the fibers and the matrix resin. Furthermore, the prepreg of the present invention exhibits excellent adhesion between the fibers and the matrix resin during molding, and foaming is suppressed during heat molding from the prepreg of the present invention, thereby obtaining a molded product with excellent appearance, such as smoothness, and water resistance.

[0030] In addition, according to the present invention, a dispersion solution having excellent dispersion stability is provided, comprising a powder of a tetrafluoroethylene-based polymer and a small amount of surfactant. The coating substrate obtained from the dispersion solution has excellent appearance with minimal surface roughness. Furthermore, when the coating substrate is bonded to another material, the adhesion is excellent. In particular, a prepreg with excellent adhesion to a matrix resin can be obtained by using a fiber as a substrate, treating the fiber with a sizing agent composed of the dispersion solution of the present invention, and impregnating the sizing-treated fiber with a matrix resin. Specific details for implementing the invention

[0031] The following terms have the following meanings.

[0032] The “average particle size” of the powder is the cumulative 50% diameter based on the volume of the object, defined as “D50” below.

[0033] "D50" is the cumulative 50% diameter based on the volume of the object obtained by the laser diffraction and scattering method. That is, the particle size distribution is measured by the laser diffraction and scattering method, and a cumulative curve is obtained with the total volume of the particle population set to 100%, and it is the particle diameter at the point where the cumulative volume becomes 50% on the cumulative curve.

[0034] "D90" is the cumulative diameter of the object based on its volume, measured in the same way.

[0035] The D50 and D90 of the object are obtained by dispersing particles in water and analyzing them using the laser diffraction and scattering method with a laser diffraction and scattering particle size distribution measuring device (manufactured by Horiba, Ltd., LA-920 measuring instrument).

[0036] "The melting temperature (melting point) of a polymer is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC).

[0037] "5% weight loss temperature of polymer" is a temperature in which a 5% weight loss is recognized when the temperature is increased at a rate of 20°C / min over a temperature range of 23 to 900°C in a nitrogen gas atmosphere using a TGA measuring device in accordance with JIS K 7120.

[0038] The "glass transition point (Tg) of a polymer" is a value measured by analyzing the polymer using the Dynamic Viscoelastic Measurement (DMA) method.

[0039] "Viscosity of the dispersion" is the viscosity measured using a Type B viscometer under conditions of 25°C and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average of the 3 measurements is used.

[0040] "Thixo-bi" is a value calculated by dividing the viscosity η1 of the liquid composition, measured under conditions of a rotation speed of 30 rpm, by the viscosity η2, measured under conditions of a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average of the three measurements is used.

[0041] "Component sedimentation rate" is a value calculated by the following formula from the height of the total dispersion in the screw tube and the height of the sedimentation layer (dispersion layer) before and after standing, when 18 mL of dispersion is placed in a screw tube with a volume of 30 mL and left to stand at 25 ℃ for 14 days. Additionally, if no sedimentation layer is observed after standing and there is no change in state, it is assumed that there is no change in the total height of the dispersion, and the component sedimentation rate is set to 100%. The higher the sedimentation rate, the better the dispersion stability.

[0042] Component Sedimentation Rate (%) = (Height of Sedimentation Layer) / (Height of Total Dispersion) × 100

[0043] In the context of a polymer, "unit" refers to an atomic group based on one molecule of the monomer formed by the polymerization of the monomer. The unit may be a unit directly formed by the polymerization reaction, or a unit in which a part of the unit is converted into a different structure by processing the polymer. Hereinafter, a unit based on monomer A is also referred to simply as a "monomer A unit."

[0044] "Tetrafluoroethylene-based polymer" means a polymer containing units based on tetrafluoroethylene.

[0045] The sizing agent of the present invention (hereinafter also referred to as "the sizing agent") contains a powder (hereinafter also referred to as "F powder") of a heat-meltable tetrafluoroethylene-based polymer (hereinafter also referred to as "F polymer") having an average particle size of 0.1 to 200 μm.

[0046] By placing the sizing agent on the fiber and heat-treating it, a sized fiber, preferably a sized carbon fiber, can be manufactured. On the surface of the obtained sized fiber, an F polymer is attached.

[0047] Fibers sized with this sizing agent are less likely to generate decomposition products when molding prepregs containing a superheat-resistant resin as a matrix resin or fiber-reinforced composite materials, thereby suppressing foaming during heat molding. Consequently, it is possible to form molded articles with particularly excellent appearance, such as smoothness, as well as adhesion and water resistance.

[0048] Although the mechanism of action is not certain, it is estimated to be approximately as follows. This sizing agent contains F polymer, and it is believed that the F polymer is more likely to be distributed more densely and homogeneously on the surface of the sizing-treated fiber obtained by treatment with this sizing agent. In addition, the F polymer is prone to forming microspheres, which increases the adhesion between the sizing-treated fiber and the matrix resin. Furthermore, since the F polymer itself has excellent heat resistance and water resistance, it is difficult to decompose even when molded at high temperatures, and it is believed to contribute to the improvement of the properties of the resulting molded product.

[0049] The average particle size (D50) of the F powder in the sizing agent is 0.1 to 200 μm. The D50 of the F powder is preferably 50 μm or less, and more preferably 30 μm or less. The D50 of the F powder is preferably 0.03 μm or more, and more preferably 0.1 μm or more.

[0050] In addition, the D90 of the F powder is preferably 10 μm or less. At D50 and D90 within this range, the fluidity of the F powder improves, making it easy for the F powder to be uniformly distributed on the fiber surface. Furthermore, the heat resistance and electrical properties (such as low dielectric constant) of the F polymer are most easily exhibited.

[0051] In the sizing agent, from the perspective of uniformly distributing F powder on the fiber surface, it is preferable that the bulk density of F powder be 0.15 g / m² or higher. It is preferable that the bulk density of F powder be 0.50 g / m² or lower.

[0052] The F powder in this sizing agent may contain resins or inorganic compounds other than the F polymer, but it is preferable that the F polymer be the main component. The content of the F polymer in the F powder is preferably 80 mass% or more, and more preferably 100 mass%.

[0053] Examples of the above resins include heat-resistant resins such as aromatic polyester, polyamideimide, thermoplastic polyimide, polyphenylene ether, and polyphenylene oxide.

[0054] Examples of the above-mentioned inorganic compounds include silica and boron nitride.

[0055] The F powder may form a core-shell structure in which the F polymer is the core and a resin or inorganic compound other than the F polymer is the shell, or it may form a core-shell structure in which the F polymer is the shell and a resin or inorganic compound other than the F polymer is the core.

[0056] The F polymer in the present invention is a heat-meltable polymer comprising a unit based on tetrafluoroethylene (hereinafter also referred to as TFE) (hereinafter also referred to as a TFE unit). The fluorine content of the F polymer is preferably 70 to 76 mass%.

[0057] The melting temperature of the F polymer is preferably 180°C or higher, more preferably 200°C or higher, even more preferably 260°C or higher, and particularly preferably 280°C or higher. The melting temperature of the F polymer is preferably 325°C or lower, and more preferably 320°C or lower. As for the melting temperature of the F polymer, 180 to 325°C is preferred, 260 to 325°C is more preferred, and 280 to 325°C is even more preferred. In this case, the heat resistance of the molded article formed from the present composition is likely to be excellent.

[0058] The glass transition point of the F polymer is preferably 50°C or higher, more preferably 75°C or higher, preferably 150°C or lower, and more preferably 125°C or lower. The glass transition point of the F polymer is preferably 75 to 125°C, and more preferably 80 to 100°C.

[0059] Examples of F polymers include a polymer (PFA) comprising a unit based on TFE and perfluoro(alkyl vinyl ether) (PAVE), a polymer (FEP) comprising a unit based on TFE and hexafluoropropene (HFP), a polymer (ETFE) comprising a unit based on TFE and ethylene, and heat-meltable polytetrafluoroethylene (PTFE). It is preferable that the polymer be PFA and FEP, and more preferable that the polymer be PFA. The polymer may also include a unit based on another comonomer.

[0060] As for PAVE, CF2= CFOCF3, CF2= CFOCF2CF3 and CF2= CFOCF2CF2CF3 (hereinafter also referred to as PPVE) are preferred, and PPVE is more preferred.

[0061] It is preferable for the F polymer to have polar functional groups, and it is more preferable for it to have atomic groups containing oxygen atoms. The polar functional groups may be included in the units of the F polymer or in the terminal groups of the main chain of the polymer. Examples of the latter embodiment include an F polymer having polar functional groups as terminal groups derived from polymerization initiators, chain transfer agents, etc., and an F polymer having polar functional groups obtained by plasma treatment or ionization treatment of the F polymer. Among the polar functional groups having atomic groups containing oxygen atoms, hydroxyl groups, carbonyl groups, and phosphono groups are preferred. From the perspective of dispersion stability when this sizing agent is used as a dispersion during fiber sizing treatment, hydroxyl groups and carbonyl groups are more preferred, and carbonyl groups are even more preferred.

[0062] When the F polymer has carbonyl groups, the number of carbonyl groups in the F polymer is 1 × 10⁻¹⁰, the number of carbon atoms in the main chain. 610 to 5000 are preferred per unit, and 100 to 3000 are more preferred. In addition, the number of carbonyl group-containing groups in the F polymer can be quantified by the composition of the polymer or by the method described in International Publication No. 2020 / 145133.

[0063] As for the hydroxyl group containing group, an alcoholic hydroxyl group containing group is preferred, and -CF2CH2OH, -C(CF3)2OH and 1,2-glycol group (-CH(OH)CH2OH) are more preferred.

[0064] The carbonyl group containing group is a group containing a carbonyl group (>C(O)). Preferably, the carbonyl group containing group is a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH2), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), and a carbonate group (-OC(O)O-), and the acid anhydride residue is more preferred.

[0065] As for the F polymer, a polymer (1) having polar functional groups including TFE units and PAVE units, and a polymer (2) not having polar functional groups including TFE units and PAVE units, with 2.0 to 5.0 mol% of PAVE units relative to the total units.

[0066] These F polymers not only exhibit excellent dispersion stability when the powder is used as a dispersion for the sizing agent, but also facilitate a denser and more homogeneous distribution on the surface of the sizing-treated fibers obtained by treatment with the sizing agent. Furthermore, they facilitate the formation of microspheres within the molded article and facilitate high adhesion between the sizing-treated fibers and the matrix resin. Additionally, due to their excellent heat resistance, molded articles with excellent appearance (surface smoothness) are more easily obtained.

[0067] The polymer (1) is preferably a polymer comprising units based on TFE units, PAVE units and monomers having polar functional groups, and more preferably a polymer comprising these units in this order of 90 to 99 mol%, 0.5 to 9.97 mol%, and 0.01 to 3 mol% with respect to the total units.

[0068] In addition, as monomers having polar functional groups, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH") are preferred.

[0069] Specific examples of polymers (1) include the polymer described in International Publication No. 2018 / 16644.

[0070] The polymer (2) is composed only of TFE units and PAVE units, and preferably contains 95.0 to 98.0 mol% of TFE units and 2.0 to 5.0 mol% of PAVE units relative to the total units. The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more relative to the total units, and more preferably 2.2 mol% or more.

[0071] These polymers have a higher degree of freedom in molecular conformation, making it easier for the mechanism of action described above to be enhanced.

[0072] In addition, the fact that the polymer (2) does not have polar functional groups is that the number of carbon atoms constituting the polymer main chain is 1 × 10 6 This means that the number of polar functional groups in the polymer is less than 500. The number of polar functional groups is preferably 100 or less, and more preferably less than 50. The lower limit of the number of polar functional groups is typically 0.

[0073] The polymer (2) may be prepared using a polymerization initiator or a chain transfer agent that does not produce a polar functional group as a terminal group of the polymer chain, or by fluorination of an F polymer having a polar functional group (such as an F polymer having a polar functional group derived from the polymerization initiator at the terminal of the main chain of the polymer). As a method of fluorination treatment, a method using fluorine gas may be used (see Japanese Patent Publication No. 2019-194314, etc.).

[0074] In the sizing agent, it is preferable to use an F polymer that exhibits non-degradability even at high temperatures. Specifically, the 5% weight loss temperature of the F polymer is preferably 360°C or higher, and more preferably 400°C or higher. The 5% weight loss temperature of the F polymer is preferably 600°C or lower.

[0075] By using an F polymer that exhibits non-degradability even at such high temperatures, foaming can be suppressed when molding a product from the prepreg described later, making it easier for the product to have an excellent appearance, such as smoothness.

[0076] This sizing agent can be used as a sizing agent for glass fibers such as E glass, D glass, L glass, S glass, T glass, Q glass, UN glass, NE glass, etc., which are used as reinforcing fibers in the technical field of fiber-reinforced plastics; organic fibers such as aramid fibers, polyolefin fibers, modified polyphenylene ether fibers, vinylon fibers, rayon fibers, polyester fibers, natural fibers; boron fibers, carbon fibers, metal fibers, etc.

[0077] The shape of the fiber may be any of chopped strands, surfacing, roving, or mats thereof, woven fabrics, nonwoven fabrics, etc. Also, there are no particular restrictions on the fiber length or cross-sectional shape.

[0078] Among them, it is preferable to use this sizing agent as a sizing agent for carbon fibers.

[0079] As carbon fibers, pitch-based, rayon-based, polyacrylonitrile (PAN)-based, single-layer carbon nanotubes, multilayer carbon nanotubes, carbon nanofibers, etc., can be used. There are no particular restrictions on the characteristics of the carbon fibers, such as fineness and strength.

[0080] Among them, acrylonitrile (PAN)-based carbon fibers are preferred in terms of maneuverability, processability, and mechanical properties. PAN-based carbon fibers are obtained by, for example, by flame-retardant treatment of a carbon fiber precursor fiber made of a PAN-based polymer at 200 to 300 °C in an oxidizing atmosphere, followed by pre-carbonization treatment at 500 to 1200 °C in an inert atmosphere, and then carbonization treatment at 1200 to 2000 °C in an inert atmosphere.

[0081] The sizing agent may be in powder form or liquid form. The liquid sizing agent consists of a dispersion containing a powder of an F polymer having an average particle size of 0.1 to 200 μm and a liquid dispersion medium (hereinafter also referred to as “the dispersion (1)”).

[0082] As a method for placing the sizing agent on the fiber, it is preferable to prepare the dispersion (1), apply it to the fiber, heat treat it, and then apply the F polymer to the surface of the fiber.

[0083] In the dispersion (1), the liquid dispersion medium for dispersing the F powder is preferably a non-protonic compound that is liquid at 25°C and classified as polar under atmospheric pressure, and more preferably a polar compound selected from amides, ketones, and esters.

[0084] When using such a liquid dispersion medium, the dispersion stability of the F powder in the dispersion is excellent.

[0085] The boiling point of the liquid dispersion medium is preferably in the range of 50 to 240°C. Two or more types of liquid dispersion media may be used in combination.

[0086] Examples of liquid dispersion media include water, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, cyclopentanone, butyl acetate, methylisopropylketone, and methyl ethyl ketone.

[0087] In the present invention, the content of the liquid dispersion medium in the dispersion (1) is preferably 30 to 90 mass%, and more preferably 50 to 80 mass%.

[0088] In the present invention, the content of F powder in the dispersion (1) is preferably 1 mass% or more with respect to the total mass of the dispersion (1), and more preferably 5 to 50 mass%.

[0089] The dispersion (1) may additionally include various surfactants added for the purpose of imparting dispersibility. When the dispersion (1) includes surfactants, the content thereof is preferably 1 to 15 mass% with respect to the total mass of the dispersion (1).

[0090] However, in the present invention, since the F powder has excellent dispersion stability, it is possible to produce the dispersion (1) with excellent dispersion stability and handling properties without necessarily using a surfactant.

[0091] For this reason, when the dispersion (1) is applied to the fiber, the sizing agent is easily dispersed uniformly on the surface of the fiber, and after heat treatment, the F polymer is easily densely and uniformly distributed on the surface of the fiber.

[0092] As surfactants, anionic, cationic, and nonionic surfactants may be used, and among them, nonionic surfactants are preferred.

[0093] The hydrophilic portion of the surfactant is preferably a polyoxyethylene group or an alcoholic hydroxyl group. The hydrophobic portion of the surfactant is preferably an acetylene group, a polysiloxane group, a fluorine-containing organic group (such as a perfluoroalkyl group), or a polyoxyalkylene group consisting of oxyalkylene having three or more carbon atoms. As surfactants, acetylene-based surfactants, silicone-based surfactants, fluorine-based surfactants, alkylamide ether-based surfactants, and glycol-based surfactants are preferred. Two or more of these surfactants may be used. When two types of surfactants are used, the surfactants are preferably a silicone-based surfactant and a glycol-based surfactant.

[0094] It is preferable that the silicone-based surfactant be the same as the silicone-based surfactant in the dispersion (2) described later.

[0095] Specific examples of such surfactants include the "Ptergent" series (manufactured by Neos Co.), the "Surfron" series (manufactured by AGC Seimi Chemical Co.), the "Megapac" series (manufactured by DIC Co.), and the "Unidine" series (manufactured by Daikin Industries Co.).

[0096] In addition to the above components, the dispersion (1) may additionally contain other components such as a thixotropic agent, a viscosity modifier, an antifoaming 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 coloring agent, a conductive agent, a release agent, a surface treatment agent, a flame retardant, various inorganic fillers, and various organic fillers, to the extent that it does not impede the effects of the present invention.

[0097] Specific examples of inorganic fillers include those identical to the inorganic filler that may be included in the dispersion (2) described below.

[0098] In addition, the dispersion (1) may additionally include a resin material other than the F polymer to improve the adhesion between the sizing agent and the matrix resin.

[0099] These resin materials may be thermosetting or thermoplastic, modified, dissolved in the dispersion (1), or dispersed without dissolving. Examples of such resin materials include tetrafluoroethylene-based polymers other than F polymers, polyimide resins, polyamic acid which is a polyimide precursor, polyamideimide resins, maleimide resins, acrylic resins, phenolic resins, liquid crystal polyester resins, liquid crystal polyesteramide resins, polyolefin resins, modified polyphenylene ether resins, polyfunctional cyanate ester resins, polyfunctional maleimide-cyanate ester resins, polyfunctional maleimide resins, vinyl ester resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, melamine-urea cocondensation resins, styrene resins, aromatic elastomers, polycarbonate resins, polyarylate resins, polysulfones, polyallylsulfones, aromatic polyamide resins, aromatic polyetheramides, polyphenylene sulfide, polyallyl ether ketones, polyamideimide, polyphenylene ether, epoxy resins, etc. As a tetrafluoroethylene-based polymer other than F polymer, non-thermo-meltable polytetrafluoroethylene is preferred in terms of improving the electrical properties of sizing-treated fibers.

[0100] When the dispersion (1) contains a resin material, the content thereof is preferably 40 mass% or less of the total dispersion (1).

[0101] It is preferable that non-heat-meltable polytetrafluoroethylene be included in the dispersion (1) as a powder of non-heat-meltable polytetrafluoroethylene. In the dispersion (1), the ratio of the content of such powder is preferably 1 or more with the content of F powder set to 1, and more preferably 2 or more. The ratio is preferably 10 or less, and more preferably 5 or less.

[0102] It is preferable that the D50 of such powder be 0.1 to 1 μm.

[0103] The viscosity of the dispersion (1) is preferably 75 to 10,000 mPa·s. In this case, in addition to excellent dispersion stability, the handling properties and the homogeneity of the sizing treatment for fibers are easily improved. Furthermore, this dispersion (1) has a higher mixing property with a varnish of a different resin material.

[0104] The tic consumption ratio of the dispersion (1) is preferably 1.0 to 2.2, and more preferably 1.5 to 2.0. In this case, in addition to excellent dispersion stability, handling properties are also good, and the homogeneity of the sizing treatment for fibers is easily improved. Furthermore, this dispersion (1) has a higher mixing ability with a varnish of a different resin material.

[0105] Methods for applying the sizing agent to the fiber (sizing treatment method) include a roller sizing method in which a portion of the roller is immersed in the dispersion (1) to attach the dispersion (1) to the roller surface, and then the fiber is brought into contact with the roller to attach the dispersion (1); a roller immersion method in which the fiber is directly immersed in the dispersion (1) and then passed through a nip roller as needed to control the amount of dispersion (1) attached; and a spray method in which the dispersion (1) is sprayed onto a fiber bundle in a mist form.

[0106] Among them, a roller immersion method is preferred for fiber bundles with a large number of short fibers per bundle, as it is easy to apply the dispersion (1) uniformly. In addition, the amount of sizing agent applied can be adjusted by adjusting the amount of excess dispersion (1) squeezed out after applying the dispersion (1).

[0107] The amount of the sizing agent (1) attached to the fiber is preferably in the range of 0.1 to 10 parts by mass per 100 parts by mass of fiber, and more preferably in the range of 0.2 to 5 parts by mass, as the amount of F polymer attached to the fiber after the heat treatment described later.

[0108] The means for dispensing the sizing agent onto the fiber may be either a batch type or a continuous type, but a continuous type is preferred from the perspective of easily suppressing non-uniformity in dispensing of the sizing agent onto the fiber and improving productivity. In addition, the fiber may be vibrated with ultrasound when applying the sizing agent.

[0109] It is preferable to heat-treat a fiber in which the dispersion (1) is placed and evaporate the dispersion medium to obtain a sizing-treated fiber with F polymer attached to its surface. It is more preferable that the F polymer attached to the surface of the fiber is a calcined product of F polymer. The sizing-treated fiber with a calcined product of F polymer attached to its surface is obtained by evaporating the dispersion medium from a fiber in which the dispersion (1) is placed and further heat-treating it to calcin the F polymer.

[0110] The heat treatment for the evaporation of the dispersion medium is carried out by maintaining the fibers containing the dispersion liquid (1) at the volatilization temperature of the dispersion medium and drying the liquid film placed on the fibers. The heat treatment for the sintering of the F polymer is carried out by maintaining the dried film at a temperature exceeding the melting temperature of the F polymer. In this way, a sintered product of the F polymer is formed on the surface of the fibers. In addition, the temperature during drying usually refers to the temperature of the drying atmosphere.

[0111] When drying, the dispersion medium does not necessarily need to be completely evaporated. Specifically, the amount of dispersion medium to be evaporated is preferably 50 mass% or more of the liquid dispersion medium contained in the dispersion (1).

[0112] Drying may be carried out in one step at a constant temperature or in two or more steps at different temperatures. Methods of drying include using an oven, using a ventilation drying oven, or irradiating with heat rays such as infrared rays, and either a contact method or a non-contact method may be adopted.

[0113] Drying may be carried out under either atmospheric pressure or reduced pressure. Additionally, the drying atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), or an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.).

[0114] The drying temperature is preferably 50 to 280 ℃. The drying time is preferably 0.1 to 30 minutes.

[0115] Methods for calcining the F polymer include using an oven, using a ventilation drying oven, or irradiating with heat rays such as infrared rays, and may also include a method combining infrared heating and hot air heating.

[0116] The calcination of the F polymer may be carried out under either atmospheric pressure or reduced pressure. In addition, the calcination atmosphere may be any of an oxidizing gas atmosphere, a reducing gas atmosphere, or an inert gas atmosphere. The calcination temperature is preferably above the melting temperature of the F polymer and below the 5% weight loss temperature of the F polymer, and is typically 300 to 380°C. The calcination time is preferably 30 seconds to 30 minutes, and more preferably 1 to 15 minutes.

[0117] When the F polymer is calcined under these conditions, productivity is increased, and it is easy to suppress the generation of hydrofluoric acid caused by the decomposition of the F polymer.

[0118] After placing the dispersion (1) on the fiber, the dispersion medium may be evaporated by contacting the carbon fiber with a heated roller, for example, by a contact drying means, and further, the F polymer may be calcined. Since the fiber introduced into the heated roller is pressed against the heated roller by tension and dried rapidly, the flattened shape of the fiber expanded by the heated roller is easily fixed by the sizing agent. As the fiber becomes flattened, the contact area between the short fibers is reduced, so the fiber opening ability is easily increased.

[0119] The sizing-treated fiber of the present invention is a fiber with an F polymer attached to its surface. The definition and scope of the F polymer are the same as those of the F polymer in the sizing agent described above, including its preferred embodiments.

[0120] The amount of F polymer attached to the sizing-treated fiber is preferably 0.1 to 10 parts by mass per 100 parts by mass of fiber, and more preferably in the range of 0.2 to 5 parts by mass.

[0121] The sizing-treated fiber of the present invention is preferably obtained from the sizing agent in the same way as the method described above.

[0122] Since the sizing-treated fibers of the present invention have excellent adhesion to the matrix resin and high impregnation of the matrix resin into the fiber bundles, it is easy to obtain prepregs with excellent mechanical properties and fiber-reinforced composite materials from these fibers.

[0123] Hereinafter, a prepreg (hereinafter also referred to as “this prepreg”) containing a sizing-treated fiber (hereinafter also referred to as “sizing-treated fiber”) of the present invention will be described.

[0124] The prepreg contains the sizing-treated fibers described above and a matrix resin, typically impregnating the sizing-treated fibers with the matrix resin. The prepreg can be manufactured, for example, by impregnating the sizing-treated fibers with the matrix resin or a matrix resin composition, and then drying and semi-curing it.

[0125] Specifically, it can be manufactured by a wet method in which a matrix resin or matrix resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol to lower viscosity and impregnate, or by a hot melt method in which viscosity is lowered by heating and impregnate.

[0126] In the wet method, prepreg can be manufactured by immersing sizing-treated fibers in a liquid containing a matrix resin, pulling them up, and evaporating the solvent using an oven or the like.

[0127] In the hot melt method, prepreg can be manufactured by a method in which a matrix resin or matrix resin composition, which has been reduced in viscosity by heating, is directly impregnated into a sizing-treated fiber, or by a method in which a film is first produced by coating a matrix resin or matrix resin composition onto a release liner or the like, and then the film is overlapped from both sides or one side of the sizing-treated fiber, and the matrix resin is impregnated into the sizing-treated fiber by applying heat and pressure. The hot melt method can be considered a desirable means in terms of not having any residual solvent in the prepreg.

[0128] Sizing-treated fibers may be used as fiber bundles or as sheet-like reinforcing fiber materials. Sheet-like materials include fibers arranged parallel in a unidirectional sheet, fiber materials formed into woven or nonwoven fabrics, and multi-axial fabrics. Sizing-treated fibers may be used as continuous fibers or as discontinuous fibers. When using discontinuous fibers, the mixture may consist of fibers that have undergone complete fiber opening treatment to become single filaments and reinforcing fibers in the form of fiber bundles that have been incompletely opened. Furthermore, the fiber orientation may be parallel in the same direction, or a random mat oriented in random directions is preferably used.

[0129] When the fibers are in the form of a sheet, the thickness is not particularly limited, but for laminated applications, a range of 0.01 to 0.2 mm is preferred, and a woven fabric that has undergone super fiber opening treatment or gap sealing treatment is preferred from the perspective of dimensional stability.

[0130] Thermosetting resins or thermoplastic resins are used as the matrix resin.

[0131] Examples of thermosetting resins include epoxy resin, unsaturated polyester resin, phenol resin, vinyl ester resin, cyanate ester resin, urethane acrylate resin, phenoxy resin, alkyd resin, urethane resin, prepolymerized resin of maleimide resin and cyanate ester resin, bis-maleimide resin, polyimide resin having acetylene ends and polyisoimide resin, polyimide resin having nadic acid ends, etc. These thermosetting resins may be used alone or in combination of two or more types. In addition, the thermosetting resin may be a thermosetting resin composition containing various additives in addition to a curing agent and a curing accelerator.

[0132] Examples of thermoplastic resins include polysulfone, polyphenylsulfone, polyethersulfone, aromatic polyetherketone (polyetherketone, polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, etc.), polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, polyamideimide, polyacetal, polyphenylene oxide, polyphenylene sulfide, liquid crystal polyester, polyarylate, polyacrylonitrile, polybenzimidazole, etc. These thermoplastic resins may be used individually or in combination of two or more types. In addition, the thermoplastic resin may be a thermoplastic resin composition containing various additives.

[0133] In addition, various additives when a thermosetting resin or thermoplastic resin is a resin composition may include plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, coloring agents, conductive agents, release agents, surface treatment agents, flame retardants, various inorganic fillers, various organic fillers, etc.

[0134] Among these, it is preferable that the matrix resin be a heat-resistant resin selected from the group consisting of polysulfone, polyphenylsulfone, polyethersulfone, aromatic polyetherketone, polyetherimide, polyphenylene sulfide, and liquid crystal polyester. These are classified as super heat-resistant resins referred to as so-called super engineering plastics, and are more likely to exhibit the effects of the sizing-treated fiber.

[0135] It is preferable that when the matrix resin has polar functional groups such as carbonyl groups, sulfone groups, and ester groups in its structure, and the F polymer of the present invention also has polar functional groups, the polar functional groups in the matrix resin interact with the polar functional groups in the F polymer to exhibit high adhesion.

[0136] The mass fraction of fibers in the prepreg is preferably 40 to 90 mass%, and more preferably 50 to 80 mass%. Within the above range, the mass of the fiber-reinforced composite material obtained is not excessive, and the advantages of the fiber-reinforced composite material with excellent specific strength and specific modulus of elasticity can be utilized.

[0137] The prepreg containing fibers sized with this sizing agent facilitates the impregnation of the matrix resin to be composited and becomes a high-quality material with minimal non-uniformity in mechanical properties.

[0138] Prepregs containing such reinforcing fibers may include various additives to the extent that they do not impede the original purpose.

[0139] The prepreg of the present invention, containing sized fibers and a matrix resin, has excellent adhesion to the matrix resin and high impregnation of the matrix resin into the fibers, so when molded, a fiber-reinforced composite material with excellent mechanical properties is obtained.

[0140] To mold fiber-reinforced composite materials using this prepreg, a method can be applied in which the prepreg is laminated, and then the matrix resin is heated while applying pressure to the laminate to form the laminate. Methods for applying heat and pressure include press molding, autoclave molding, bagging molding, wrapping tape molding, and pressure molding. In particular, for sports goods, wrapping tape molding and pressure molding are preferred. For aircraft applications requiring higher quality and high-performance laminated composite materials, autoclave molding is preferred. For various vehicle exteriors, press molding is preferred.

[0141] In addition, when molding fiber-reinforced composite materials using this prepreg, resin transfer molding, filament winding molding, sheet winding molding, etc., can also be applied.

[0142] In addition, a metal-coated laminate is obtained by overlapping the prepregs described above and placing a metal substrate on one or both sides thereof and laminating it. Specifically, a metal-coated laminate can be produced by overlapping one or multiple sheets of the prepregs described above and placing a metal substrate on one or both sides thereof and laminating it. Examples of metals constituting the metal substrate include iron, stainless steel, aluminum, copper, brass, nickel, zinc, titanium, or alloys of these metals.

[0143] As for the forming conditions, the methods of conventional laminates and multilayer boards for printed circuit boards can be applied. For example, a metal-clad laminate can be manufactured by using a multi-stage press, a multi-stage vacuum press, a continuous forming machine, an autoclave forming machine, etc., and laminating at a temperature of 180 to 350°C, a heating time of 100 to 300 minutes, and a surface pressure of 20 to 100 kg / cm².

[0144] The fiber composite material may additionally have other substrates laminated thereon. Examples of other substrates include heat-resistant resin films and prepregs that are precursors of fiber-reinforced resin plates. Examples of such fiber composite materials include fiber-reinforced composite materials having a heat-resistant resin film layer and fiber-reinforced composite materials having a prepreg layer.

[0145] A heat-resistant resin film is a film containing one or more types of heat-resistant resins, and the heat-resistant resins may include the resins mentioned above.

[0146] As a method of lamination, a method of heat-pressing a laminate obtained by laminating prepregs and heating them with a different substrate can be cited.

[0147] When the other substrate is prepreg, the conditions for the heat press are preferably to set the temperature to 120 to 400°C, the pressure of the atmosphere to a vacuum of 20 kPa or less, and the press pressure to 0.2 to 10 MPa.

[0148] The fiber-reinforced composite material of the present invention is preferably used in applications requiring strength, wear resistance, chemical resistance, and flame retardancy. Examples include exteriors and interiors of transportation equipment such as automobiles, motorcycles, and aircraft; sliding parts such as gears and bearings; insulating parts; sports equipment such as rackets and bats; parts of industrial machinery, robots, and medical devices; oil drilling rigs; oil transport hoses; hydrogen tanks; hydrogen tank pressure vessels; and blades of wind turbines.

[0149] In addition, the fiber-reinforced composite material and the laminate of the present invention may also be used as low-vibration members. Examples of members requiring low vibration include rotating parts of motors, rotating parts of compressors, rotating parts of machine tools (lathes, pestles, etc.), and interior and exterior parts of transport equipment such as automobiles, motorcycles, and aircraft.

[0150] In addition, the fiber-reinforced composite material of the present invention can be used in components used at ultra-low temperatures, such as liquid hydrogen tanks, due to its excellent mechanical properties at low temperatures.

[0151] In the sizing agent, it is more preferable that the average particle size of the F powder is 10 to 100 μm. A dispersion (hereinafter also referred to as the dispersion (2)) comprising the F powder of this average particle size, a surfactant, and a liquid dispersion medium, wherein the surfactant content is 0.01 parts by mass or less per 1 part by mass of the F powder of this average particle size, has particularly excellent dispersion stability and is therefore preferred as the sizing agent. In addition, the dispersion (2) can be used for purposes other than the sizing agent due to its characteristics.

[0152] The average particle size (D50) of the F powder in the dispersion (2) is preferably 50 μm or less, and more preferably 40 μm or less. In addition, the average particle size of the F powder in the dispersion (2) is preferably 20 μm or more.

[0153] In addition, the D90 of the F powder in the dispersion (2) is preferably 40 μm or more and more preferably 60 μm or more from the perspective of the dispersibility of the dispersion (2). Also, the D90 of the F powder in the dispersion (2) is preferably 100 μm or less and more preferably 90 μm or less.

[0154] Since F powder has low surface energy and is prone to aggregating with each other, the dispersion (2) contains a surfactant. The amount of surfactant is 0.01 or less per 1 mass part of F powder. Because the F powder in the dispersion (2) has a relatively large average particle size and a small surface area, it is highly stabilized by a small amount of surfactant and dispersed in a dispersion medium, so the dispersion (2) has excellent dispersion stability.

[0155] In addition, since the surfactant content of this dispersion (2) is smaller than the F powder content, when used in the manufacture of the coating substrate described later, the surface roughness of the resulting coating substrate is minimal and the appearance is excellent. Also, when the obtained coating substrate is bonded to another material, the adhesion is excellent. In particular, by using a fiber as a base, treating the fiber with a sizing agent made of this dispersion (2), and impregnating the sizing-treated fiber with a matrix resin, a prepreg with excellent adhesion can be obtained.

[0156] From the perspective of the appearance of the surface of the coated substrate obtained, the content of the surfactant in the dispersion (2) is preferably 0.008 or less per 1 part by mass of F powder, and more preferably 0.005 or less. Also, from the perspective of dispersibility, the content of the surfactant is preferably 0.0001 or more per 1 part by mass of F powder.

[0157] The above surfactants are preferably the aforementioned silicone-based surfactants, fluorine-based surfactants, glycol-based surfactants, and alkylamide ether-based surfactants. Two or more of these surfactants may be used. If two or more are used, the sum of their contents must fall within the above content range. When two types of surfactants are used, it is preferable that the surfactants consist of a silicone-based surfactant and a glycol-based surfactant.

[0158] The surface tension of the surfactant is preferably 28 mN / m or less, and more preferably 26 mN / m or less. The surface tension of the surfactant is preferably 20 mN / m or more. The surfactant is preferably non-ionic.

[0159] A silicone-based surfactant is a surfactant in which a hydrophilic substituent is introduced to a portion of silicone having a main backbone consisting of siloxane bonds in which silicon and oxygen are alternately linked by chemical bonds. Examples include organopolysiloxane, polyether-modified polysiloxane, polyester-modified polysiloxane, aralkyl-modified polysiloxane, and acrylic-modified polysiloxane.

[0160] Fluorinated surfactants are surfactants having a hydrophilic portion having a hydroxyl group, a carboxyl group, a sulfonate group, or a group derived from these groups, and a hydrophobic portion having a fluorine-containing organic group. Examples include the "Ptergent" series (Ptergent manufactured by Neos Co., Ltd. is a registered trademark), the "Surfron" series (Surfron manufactured by AGC Seimi Chemical Co., Ltd. is a registered trademark), the "Megapac" series (Megapac manufactured by DIC Co., Ltd. is a registered trademark), and the "Unidine" series (Unidine manufactured by Daikin Industries Co., Ltd. is a registered trademark).

[0161] Glycol-based surfactants are surfactants composed of glycol derivatives in which hydrophilic groups, such as hydroxyl groups and ester groups, are combined with hydrophobic groups, such as hydrocarbon groups. Examples include glycol monoalkyl ethers, glycol monoaryl ethers, glycol monoalkyl ether acetates, and glycol monoaryl ether acetates.

[0162] Alkylamide ether surfactants are nonionic surfactants in which a carboxylic acid and a polyoxyalkylamine are amide-bonded. Examples include polyoxyethylenealkylamide and polyoxyethyleneoleic acidamide.

[0163] Among the surfactants mentioned above, silicone-based surfactants are more preferable in terms of dispersion stability of the dispersion.

[0164] Among silicone-based surfactants, organopolysiloxane is preferred, and polyether-modified polysiloxane, polyester-modified polysiloxane, aralkyl-modified polysiloxane, or acrylic-modified polysiloxane is preferred.

[0165] The organopolysiloxane may have an organopolysiloxane structure in the main chain, an organopolysiloxane structure in the side chain, or an organopolysiloxane structure in both the main chain and the side chain. The organopolysiloxane is preferably a linear polymer. The organopolysiloxane is more preferably a polydiorganosiloxane.

[0166] As for organopolysiloxane, dimethylsiloxane units ((CH3)2SiO2 2 / 2 An organopolysiloxane comprising ) is preferred, an organopolysiloxane (1) having a dimethylsiloxane unit in the main chain and a polyoxyalkylene at the end of the main chain, or, a dimethylsiloxane unit and formula (R 1 ) (R 2 ) SiO 2 / 2 Organopolysiloxane (2) containing a diorganosiloxane unit represented by R is more preferable. However, R in the formula 1Silver represents an alkyl group, and a methyl group is preferred. Also, R in the formula 2 represents a group having a polyoxyalkylene, and formula -X 2 -OY 2 -Z 2 The element represented by (among the formulas, X 2 is an alkylene group, Y 2 is a polyoxyalkylene group, Z 2 represents any of the hydrogen atom, alkyl group, or acyl group.) is preferred.

[0167] The polyoxyalkylene included in organopolysiloxane (1) or (2) may consist of only one type of oxyalkylene group or two or more types of oxyalkylene groups. In the latter case, the different types of oxyalkylene groups may be connected randomly or in a block.

[0168] In polyoxyalkylene, the oxyalkylene group is preferably an oxyethylene group or an oxypropylene group.

[0169] The number of oxyalkylene group units (degree of polymerization) in the polyoxyalkylene is preferably 2 or more. The number of oxyalkylene group units is preferably 100 or less, more preferably 50 or less, and even more preferably 20 or less.

[0170] The degree of polymerization of the organopolysiloxane is preferably 2 or higher. The degree of polymerization of the organopolysiloxane is preferably 1000 or lower, more preferably 100 or lower, and even more preferably 50 or lower.

[0171] In organopolysiloxane (2), the ratio of the number of dimethylsiloxane units to the number of diorganosiloxane units (degree of polymerization) is preferably greater than 1. The ratio is preferably 20 or less.

[0172] The weight average molecular weight of the organopolysiloxane is preferably 300 to 100,000, more preferably 500 to 10,000, and even more preferably 500 to 2,000.

[0173] The HLB of the organopolysiloxane is preferably 8 to 18.

[0174] In addition, the above HLB value is a value calculated using the Griffin formula, and is a value obtained by dividing the total sum of the hydrophilic portions by the molecular weight and multiplying it by 20. In the case of organopolysiloxane (1) or (2), the polyoxyalkylene in the organopolysiloxane is the hydrophilic portion, and the value is obtained by dividing the molecular weight of the polyoxyalkylene by the molecular weight of the organopolysiloxane and multiplying it by 20.

[0175] Specific examples of organopolysiloxanes include “BYK-347”, “BYK-349”, “BYK-378”, “BYK-3450”, “BYK-3451”, “BYK-3455”, “BYK-3456” (manufactured by Big Chem Japan), “KF-6011”, and “KF-6043” (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0176] The boiling point of the liquid dispersion medium in the dispersion (2) is preferably 75°C or higher, and more preferably 100°C or higher. The boiling point of the dispersion medium is preferably 300°C or lower, and more preferably 250°C or lower.

[0177] The liquid dispersion medium may be water, may be a non-aqueous liquid dispersion medium, and is preferably a liquid dispersion medium selected from the group consisting of water, alcohol, amide, ketone, ester, and hydrocarbon.

[0178] The non-aqueous liquid dispersion medium may or may not be fluorinated. As alcohols, methanol, ethanol, isopropanol, butanol, and hexanol are preferred. As amides, dimethylformamide, acetanilide, and N-methyl-2-pyrrolidone are preferred. As ketones, acetone, methyl ethyl ketone, diisobutyl ketone, and methyl isobutyl ketone are preferred. As esters, ethyl acetate, butyl acetate, ethyl benzoate, and butyl benzoate are preferred. As hydrocarbons, pentane, hexane, heptane, octane, toluene, and xylene are preferred.

[0179] The liquid dispersion medium may be a mixture of two or more types. It is preferable that the liquid dispersion medium be degassed to prevent a decrease in the uniformity of the component distribution of the molded product obtained using the dispersion liquid (2) and to suppress voids.

[0180] Among these liquid dispersion media, water is more preferable.

[0181] In the context of manufacturing the coating substrate described below, the amount of F powder in the dispersion (2) is preferably 25 to 100 parts by mass relative to 100 parts by mass of the liquid dispersion medium, from the perspective that the substrate can be efficiently coated with a large amount of F powder. Normally, since F powder has low surface energy and tends to aggregate with each other, the amount of F powder in the dispersion is suppressed to a low level, but the dispersion (2) has excellent dispersion stability even when the amount of F powder is increased. Therefore, even if the amount of F powder in the dispersion is increased, the stability of the dispersion, the impregnation and coating properties of the substrate are excellent, and a substrate with excellent surface appearance can be obtained even when a large amount of F powder is coated or impregnated into the substrate. From the above perspective, the amount of F powder in the dispersion (2) is more preferably 40 parts by mass or more relative to 100 parts by mass of the liquid dispersion medium.

[0182] The dispersion (2) is obtained by mixing F powder, a predetermined amount of surfactant, and a dispersion medium. Mixing methods include mixing F powder, a predetermined amount of surfactant, and a dispersion medium together, or mixing a predetermined amount of surfactant and a dispersion medium in advance and then adding F powder thereto. Addition may be done collectively, continuously, or intermittently.

[0183] Mixers used for mixing include mixing blade mixers, Henschel mixers, ribbon blenders, oscillating mixers, and vibrating mixers.

[0184] The mixing method may be either batch or continuous.

[0185] For batch mixing, Henschel mixers, pressurized kneaders, Banbury mixers, and planetary mixers are preferred.

[0186] The temperature of mixing the F powder, a predetermined amount of surfactant, and the dispersion medium is not particularly limited as long as the F powder is uniformly dispersed, but is typically carried out at 20°C or higher. In addition, mixing is carried out at a temperature lower than the boiling point of the dispersion medium, and it is preferable to carry out mixing at 100°C or lower.

[0187] The dispersion (2) may further contain at least one selected from the group consisting of inorganic fillers and aromatic polymers (hereinafter also referred to as the third component).

[0188] When containing inorganic fillers, the molded product obtained by applying this dispersion (2) to a substrate is likely to have excellent electrical properties and low linear expansion.

[0189] When containing an aromatic polymer, the molded product obtained by applying the dispersion (2) to a substrate is likely to have excellent adhesion and UV processability.

[0190] In the above view, as for inorganic fillers, nitride fillers and inorganic oxide fillers are preferred, silicate fillers such as boron nitride filler, aluminum nitride filler, beryllia filler (a filler of beryllium oxide), silica filler, wollastonite filler, and talc filler are more preferred, and metal oxide fillers such as cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, and titanium oxide are more preferred. Silica fillers are even more preferred.

[0191] It is preferable that the inorganic filler be surface-treated with a silane coupling agent.

[0192] The D50 of the inorganic filler is preferably 20 μm or less, and more preferably 10 μm or less. The D50 is preferably 0.01 μm or more, and more preferably 0.1 μm or more.

[0193] The shape of the inorganic filler may be granular, needle-shaped (fibrous), or plate-shaped. Specific shapes of the inorganic filler include spherical, scale-shaped, lamellar, leaf-shaped, apricot-shaped, columnar, cock-shaped, isometric, leaf-shaped, mica-shaped, block-shaped, flat, wedge-shaped, rosette-shaped, reticulate, and prismatic shapes.

[0194] Preferred specific examples of inorganic fillers include silica fillers (such as the "AdmaFine" (registered trademark) series manufactured by Admatex, etc.), zinc oxide surface-treated with an ester such as propylene glycol dicaprate (such as the "FINEX" (registered trademark) series manufactured by Sakai Chemical Industry Co., Ltd.), spherical fused silica (such as the "SFP" (registered trademark) series manufactured by Denka, etc.), titanium oxide coated with polyhydric alcohols and inorganic materials (such as the "Taipeike" (registered trademark) series manufactured by Ishihara Sangyo, etc.), rutile-type titanium oxide surface-treated with alkylsilane (such as the "JMT" (registered trademark) series manufactured by Teika, etc.), hollow silica fillers (such as the "E-SPHERES" series manufactured by Taiyo Cement, the "Sirinax" series manufactured by Nittetsu Mining, the "Ecocosphere" series manufactured by Emerson & Calming, etc.), and talc fillers (such as the "SG" series manufactured by Nippon Talc, etc.). Examples include steatite 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, and the "Dencarboron Nitride" series manufactured by Denka Co., Ltd. ("GP", "HGP" grades), etc.).

[0195] As aromatic polymers, aromatic elastomers such as aromatic polyimide, aromatic polyamide, aromatic polyamideimide, aromatic maleimide, and styrene elastomer, and aromatic polyamic acid are preferred; aromatic elastomers such as aromatic polyimide, aromatic polyamideimide, aromatic maleimide, polyphenylene ether, and styrene elastomer are more preferred; and aromatic polyimide, aromatic polyamideimide, and aromatic polyamic acid are even more preferred. Aromatic polyimide may be thermoplastic or thermosetting. A thermoplastic polyimide refers to a polyimide in which imidization is complete and no further imidization reaction occurs.

[0196] Specific examples of aromatic polyimides include the "Neoprim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), "Spiceria (registered trademark)" series (manufactured by Somall Co., Ltd.), "Q-PILON (registered trademark)" series (manufactured by PI Technical Research Institute), "WINGO" series (manufactured by Wingo Technology Co., Ltd.), "Tomide (registered trademark)" series (manufactured by T & K TOKA Co., Ltd.), "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.), and "UPIA (registered trademark)-AT" series (manufactured by Ube Kogyo Co., Ltd.).

[0197] Specific examples of aromatic polyamideimide include “HPC-1000” and “HPC-2100D” (both manufactured by Showa Denko Materials Co., Ltd.).

[0198] Examples of styrene elastomers include styrene-butadiene copolymer, hydrogenated-styrene-butadiene copolymer, hydrogenated-styrene-isoprene copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer.

[0199] The dispersion (2) may additionally include non-thermo-meltable polytetrafluoroethylene powder as a third component. In this case, the molded product formed from the dispersion (2) is likely to have excellent electrical properties. In the dispersion (2), the mass ratio of the content of such powder is preferably 0.5 or more with the content of F powder set to 1, and more preferably 1 or more. The above ratio is preferably 10 or less, and more preferably 5 or less.

[0200] It is preferable that the D50 of such powder be 0.1 to 1 μm.

[0201] When mixing the above third component, the mixing method may be the same as the mixing method described above.

[0202] When mixing the above third component, the third component may be added at any stage of preparing the dispersion. For example, the third component may be mixed in advance with F powder and / or a predetermined amount of surfactant, or the third component may be added when mixing F powder, a predetermined amount of surfactant, and a dispersion medium. Alternatively, a mixture of F powder, a predetermined amount of surfactant, and a dispersion medium may be mixed in advance with a mixture of the third component and a dispersion medium, or the third component may be added to the dispersion after the dispersion is obtained. Addition may be carried out in a batch or in a divided manner, and may be added continuously or intermittently.

[0203] The component sedimentation rate of the dispersion (2) obtained by the above is preferably 60% or more, and more preferably 70% or more. The upper limit of the component sedimentation rate is 100%. The dispersion (2) is likely to have excellent dispersion stability due to the mechanism of action described above.

[0204] The dispersion (2) obtained by the above is preferably 10 mPa·s or more, and more preferably 20 mPa·s or more, in terms of coating properties or impregnation properties for the substrate when manufacturing the coating substrate described later. The viscosity of the dispersion (2) is preferably 100,000 mPa·s or less, more preferably 10,000 mPa·s or less, and even more preferably 2,000 mPa·s or less. The viscosity of the dispersion (2) can be set to a desired range by controlling the amount of F powder and the type and amount of the dispersion medium.

[0205] The tick consumption ratio of the dispersion (2) is preferably 1.0 to 2.2. The dispersion (2) having such a tick consumption ratio has excellent coating properties, impregnation properties, and homogeneity. In addition, the tick consumption ratio is calculated by dividing the viscosity of the dispersion (2) measured under conditions of a rotational speed of 30 rpm by the viscosity of the dispersion (2) measured under conditions of a rotational speed of 60 rpm.

[0206] From the perspective of reducing the uniformity of the component distribution of the molded article obtained from the dispersion (2) or suppressing voids, the foam volume ratio in the dispersion (2) is preferably less than 10%, and more preferably less than 5%. The foam volume ratio is preferably 0% or more.

[0207] In addition, the foam volume ratio is the volume (V) of the dispersion (2) at standard atmospheric pressure and 20°C. N ) and the combined volume of bubbles when it is depressurized to 0.003 MPa (V V ) is measured and is a value obtained using the following formula.

[0208] Foam volume ratio [%] = 100 × (V V - V N ) / V N am.

[0209] In the case where the solid content of the dispersion (2) contains the third component, the third component is also included in the solid content. In addition, the solid content of the dispersion (2) includes other insoluble components in the dispersion (2) other than the F powder. The concentration of the solid content is preferably 25 mass% or more and 50 mass% or more, with the total mass of the dispersion being 100 mass%. Also, from the perspective of the dispersibility of the dispersion (2), the solid content concentration is preferably 80 mass% or less and 60 mass% or less. The amount of F powder in the solid content is preferably 50 mass% or more and 70 mass% or more, with the total mass of the solid content being 100 mass%. Also, the amount of F powder in the solid content is preferably 99 mass% or less.

[0210] In addition to the above components, the dispersion (2) may additionally contain other components such as a thixotropic agent, a viscosity modifier, an antifoaming 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 coloring agent, a conductive agent, a release agent, a surface treatment agent, a flame retardant, and various organic fillers.

[0211] By contacting the dispersion (2) with a substrate and firing it to form a layer made of F polymer (hereinafter also referred to as "F layer"), a coated substrate coated with the F layer can be manufactured. Examples of contact methods include applying the dispersion (2) to the surface of the substrate, immersing the substrate in the dispersion (2) and impregnating the substrate with the dispersion (2), or spraying the dispersion (2) onto the substrate.

[0212] Examples of substrates include metal foil, resin film, woven fabric, nonwoven fabric, fiber, etc. Preferred embodiments of the coating substrate include a metal coating laminate having a metal foil and an F layer formed on at least one surface thereof, a multilayer film having a resin film and an F layer formed on at least one surface thereof, and a coated woven fabric in which the fibers in the woven fabric or nonwoven fabric are coated with an F layer by impregnating the woven fabric or nonwoven fabric with the dispersion (2). Alternatively, the fibers may be coated with an F polymer by contacting the woven fabric or nonwoven fabric directly with the dispersion (2) and firing.

[0213] The F layer may cover the entire surface of the substrate or cover a part of it, and the F polymer may be attached to the surface of the substrate. The F layer may have holes.

[0214] Examples of metal foils include metal substrates such as metal foils made of copper, nickel, aluminum, titanium, and their alloys. Examples of resin films include resin films made of polyimide, polyarylate, polysulfone, polyallylsulfone, polyamide, polyetheramide, polyphenylene sulfide, polyallyletherketone, polyamideimide, liquid crystal polyester, liquid crystal polyesteramide, F polymer, non-heat-melting tetrafluoroethylene-based polymer, and prepregs which are precursors of fiber-reinforced resin substrates. As for the F polymer and non-heat-melting tetrafluoroethylene-based polymer in the resin film, PTFE, PFA, and FEP are preferred. The shape of these metal foils or resin films may be planar, curved, or uneven, and furthermore, may be any of a thin film, plate, membrane, or fibrous shape.

[0215] Specific examples of the coating substrate include a metal foil and a metal coating laminate having an F layer on at least one surface of the metal foil, and a polyimide film and a multilayer film having an F layer on both surfaces of the polyimide film. These laminates are desirable as printed circuit board materials because they have excellent general physical properties such as electrical properties. Specifically, these laminates can be used to manufacture flexible printed circuit boards or rigid printed circuit boards.

[0216] The metal foil is preferably copper foil. A metal-clad laminate in which the substrate is copper foil is particularly useful as a printed circuit board material.

[0217] The 10-point average roughness of the surface of the metal foil is preferably 0.01 to 0.05 μm.

[0218] The resin film is preferably a polyimide film or a F polymer film. A multilayer film in which the substrate is such a film is useful as a wire sheathing material or a printed circuit board material.

[0219] In the manufacture of a metal-coated laminate having an F layer or a multilayer film having an F layer, the F layer may be formed on at least one surface of the substrate, or the F layer may be formed on only one surface of the substrate, or the F layer may be formed on both surfaces of the substrate. The surface of the substrate may be surface-treated with a silane coupling agent, etc. When applying the dispersion, a spray method, roll coating method, spin coating method, gravure coating method, micro-gravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, Fountain Mayer bar method, and slot die coating method may be used.

[0220] When the dispersion (2) is impregnated into a woven fabric and dried by heating, the woven fabric is coated with an F layer, and a sizing-treated coated woven fabric is obtained. As for the woven fabric, glass fiber woven fabric, carbon fiber woven fabric, aramid fiber woven fabric, and metal fiber woven fabric are preferred, and glass fiber woven fabric and carbon fiber woven fabric are more preferred. Methods for impregnating the woven fabric with the dispersion (2) include immersing the woven fabric in the dispersion (2) and applying the dispersion to the woven fabric.

[0221] When the dispersion (2) is brought into contact with the surface of the fiber and calcined to attach the F layer to the surface of the fiber, a coated fiber is obtained in which the fiber is coated with the F layer. As for the fiber, the same as the reinforcing fiber that can use the sizing agent described above can be used.

[0222] By coating the above fiber with a layer of F, a sizing effect is obtained that suppresses fiber breakage and lint formation. When the dispersion (2) is used as a sizing agent, additives that are appropriately necessary for the fiber used may be added to the dispersion (2). Fibers sized by the dispersion (2) have excellent heat resistance and adhesion to other polymers.

[0223] It is preferable that the surface tension of the above substrate be greater than the surface tension of the above surfactant. In this case, the substrate is easily wetted by the dispersion (2), and the surface of the coated substrate is less likely to become rough. It is preferable that the surface tension of the above substrate be at least 5 mN / m greater than the surface tension of the above surfactant, and more preferable that it be at least 10 mN / m greater. For example, if the surface tension of the above surfactant is 28 mN / m or less, it is particularly preferable that the surface tension of the substrate be at least 35 mN / m.

[0224] It is preferable to form the F layer by further calcining the F polymer after removing the dispersion medium by heating. The temperature for removing the dispersion medium is preferably a temperature below the boiling point of the dispersion medium, and more preferably a temperature 50 to 150°C lower than the boiling point. For example, when using N-methyl-2-pyrrolidone with a boiling point of about 200°C, it is preferable to heat at 150°C or lower, preferably 100 to 120°C. For example, when using water with a boiling point of about 100°C, it is preferable to heat at 90°C or lower, preferably 70 to 80°C. It is preferable to spray air during the process of removing the dispersion medium.

[0225] After removing the dispersion medium, it is preferable to heat the substrate to a temperature range in which the F polymer is calcined to form an F layer, and for example, it is preferable to calcin the polymer in a range of 300 to 400 ℃. It is preferable that the F layer comprises a calcined product of the F polymer.

[0226] The F layer is formed by the process of contacting the dispersion (2) with the substrate as described above, the process of removing the dispersion medium, and the process of calcining the F polymer. These processes may be performed once or more than twice. For example, the dispersion (2) is applied to the substrate, and the dispersion medium is removed by heating to form a film. The film may also be formed by additionally applying the dispersion (2) on top of the formed film, removing the dispersion medium by heating, and further calcining the F polymer by heating. From the perspective of obtaining a thick film with excellent appearance, the processes of applying, drying, and calcining the dispersion (2) may be performed twice.

[0227] The thickness of the F layer is preferably 0.1 μm or more, and more preferably 1 μm or more. The upper limit of the thickness is 200 μm. Within this range, an F layer with excellent crack resistance can be easily formed.

[0228] The peel strength of the F layer and the substrate is preferably 10 mN / m or more, and more preferably 15 mN / m or more. The peel strength is preferably 100 mN / m or less. By using this dispersion (2), such a laminate can be easily formed without damaging the physical properties of the F polymer in the F layer.

[0229] The porosity of the F layer is preferably 20% or less, and more preferably 10% or less. The porosity is preferably 0.1% or more. In addition, the porosity is the ratio (%) obtained by determining the void portion of the F layer through image processing from a SEM photograph of a cross-section of a molded article observed using a scanning electron microscope (SEM), and dividing the area occupied by the void portion by the area of ​​the F layer. The area occupied by the void portion can be obtained by approximating the void portion to a circular shape.

[0230] Examples of the composition of the metal-clad laminate or multilayer film include substrate / F layer / substrate / F layer / substrate, substrate / substrate / F layer / substrate / substrate, etc. Each substrate may be the same or different, and additionally, the substrate or F layer may include a glass cross or a filler.

[0231] These metal-clad laminates are useful as antenna components, printed circuit boards, aircraft parts, automotive parts, sports equipment, food industry supplies, heat dissipation components, paints, cosmetics, etc. Specifically, they are used as wire sheathing materials such as aircraft wires, enameled wire sheathing materials used for motors of electric vehicles, electrical insulating tapes, insulating tapes for oil drilling, materials for printed circuit boards, separators such as precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, and gas separation membranes, electrode binders for lithium secondary batteries and fuel cells, copy rolls, covers for furniture, automotive dashboards, and home appliances, sliding members such as load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, and food transport belts, tools such as shovels, files, awls, and saws, boilers, hoppers, pipes, ovens, roasting molds, chutes, dies, toilets, container coverings, power devices, transistors, thyristors, rectifiers, transformers, power MOS FETs, CPUs, and as heat dissipation fins or metal heat sinks. It is useful.

[0232] More specifically, it is useful as a sealing material for processing machines, vacuum ovens, plasma processing devices, etc., which heat-treat under low oxygen conditions, such as PC or display casings, electronic device materials, and automotive interiors and exteriors, or as a heat dissipation component in processing units such as sputters and various dry etching devices.

[0233] In addition, this dispersion (2) can be used to form a heat-conductive heat-resistant coating layer by impregnating it into an insulating layer of a printed circuit board, a thermal interface material, a substrate for a power module, or a coil used in a power device such as a motor, and drying it, or to bond ceramic parts or metal parts together in a vehicle engine, or to provide corrosion resistance to a heat exchanger or the fins or tubes that make up the heat exchanger.

[0234] In addition, the dispersion (2) is preferred as a sizing agent, and when the dispersion (2) is used as a sizing agent, the adhesion between the reinforcing fiber and the matrix resin is improved in fiber-reinforced plastics containing reinforcing fibers and matrix resins, in that the appearance of the fibers coated with the F layer is excellent. Therefore, prepregs containing fibers and matrix resins that have been sized by contacting the dispersion (2) with the fibers have excellent mechanical properties. Also, since the F layer has excellent heat resistance, such prepregs tend to have excellent surface smoothness even when processed at high temperatures.

[0235] Reinforcing fibers may include the same fibers as above, among which carbon fibers, glass fibers, aramid fibers, and boron fibers are preferred.

[0236] As for the matrix resin, the same as the matrix resin in this prepreg can be cited.

[0237] Since the F layer has excellent heat resistance, when using this heat-resistant resin as a matrix resin to mold prepreg or to further process prepreg, it is difficult to decompose even when heated, and the prepreg or the processed product is likely to have excellent surface smoothness.

[0238] A manufacturing method for obtaining prepreg from the dispersion (2) can be the same as the manufacturing method for obtaining prepreg from the dispersion (1) described above.

[0239] The prepreg obtained from this dispersion (2) can be further formed into a fiber-reinforced composite material in the same way as the method of forming the prepreg into a fiber-reinforced composite material described above.

[0240] As described above, the dispersion (2) has excellent dispersion stability, and the coated substrate coated with an F layer using the dispersion (2) has excellent surface appearance and excellent adhesion to other substrates. In particular, by coating fibers with an F layer using the dispersion (2), a sizing effect is obtained that suppresses fiber breakage and lint formation. Therefore, the dispersion (2) is preferably used as a sizing agent. When the dispersion (2) is used as a sizing agent, the appearance of the fiber coated with an F layer is excellent, and the adhesion between the reinforcing fiber and the matrix resin is improved in fiber-reinforced plastics containing reinforcing fibers and a matrix resin. Therefore, prepreg containing fibers and a matrix resin that have been sized by contacting the fibers with the dispersion (2) has excellent mechanical properties.

[0241] Although the sizing agent, the dispersion (1), the sizing-treated fiber, and the dispersion (2) have been described above, the present invention is not limited to the configuration of the embodiments described above.

[0242] For example, the sizing agent, the dispersion (1), the sizing-treated fiber, and the dispersion (2) may have any other composition added to the composition of the above embodiment, or may be substituted with any composition that performs the same function.

[0243] Examples

[0244] The present invention will be described in detail below by way of examples, but the present invention is not limited thereto. Details of each component are shown below.

[0245] <Example 1>

[0246] 1-1. Preparation of Each Component

[0247] [F Powder]

[0248] F Powder 11: Acid anhydride residue containing TFE units, NAH units, and PPVE units in this order, at 97.9 mol%, 0.1 mol%, and 2.0 mol%, respectively, with a main chain having 1 × 10 carbon atoms. 6 Powder composed of polymers having 1,000 units per particle (melting temperature 300 ℃, 5% weight loss temperature: 400 ℃ or higher) (average particle size 2 µm, bulk density 0.18 g / m²)

[0249] F Powder 12: Powder consisting of a polymer without polar functional groups containing 97.5 mol% and 2.5 mol% of TFE units and NAH units in this order (melting temperature 305 °C, 5% weight loss temperature: 400 °C or higher) (average particle size 2 μm, bulk density 0.19 g / m²)

[0250] [Epoxy Resin]

[0251] Epoxy Resin 1: "Epicote 828" manufactured by Japan Epoxy Resin Co.

[0252] In addition, the polymer of F powder 11 has carbonyl groups in a main chain with 1 × 10 carbon atoms. 6 Each has 1,000.

[0253] [Surfactant]

[0254] Surfactant A: Polyoxyethylene / polyoxypropylene / polyoxyethylene triblock copolymer ("Pluronic F88" manufactured by Asahi Denka)

[0255] [Carbon Fiber]

[0256] Carbon Fiber 1: "MR50R" manufactured by Mitsubishi Chemical

[0257] [Liquid dispersion medium]

[0258] NMP: N-methyl-2-pyrrolidone

[0259] [film]

[0260] Film 1: Film obtained by melt extrusion of polyetherketone ketone ("Kepstan 7003" manufactured by Arkema, France) (Thickness: 15 μm)

[0261] 1-2. Preparation of the dispersion of the sizing agent and placement into carbon fibers

[0262] [Example 1-1]

[0263] (1) First, F powder 11 (10 parts by mass) and NMP (90 parts by mass) were added to the pot, and zirconia balls were added. Then, the pot was run at 150 rpm for 1 hour, and dispersion 11 (viscosity: 400 mPa·s) was obtained.

[0264] (2) The dispersion 11 obtained in (1) above was placed on carbon fibers by the roller immersion method, passed through a drying oven at 120°C for 5 minutes, and then heated and dried. After that, it was heated in a far-infrared oven at 340°C for 10 minutes and calcined to obtain a sizing-treated carbon fiber (hereinafter referred to as carbon fiber T1) in which the calcined product of F powder 11 was attached to the surface of the carbon fibers.

[0265] (3) Film 1 was layered on both sides of a carbon fiber substrate in the form of a sheet with an apparent weight of 75 g / m² and carbon fiber T1 oriented in one direction, and two films 1 were heated and melted to impregnate the carbon fiber substrate to produce prepreg 1.

[0266] After cutting prepreg 1 to a predetermined size, it was laminated within a steel mold such that the fiber axis directions of each prepreg were aligned in a single direction. The mold on which the laminated body was placed was compressed at 380°C and 5 MPa for 30 minutes using a two-stage heating and cooling press (manufactured by Shinto Metal Industry Co., Ltd., 50-ton press), and then cooled down to 200°C in a few minutes to obtain a laminated body 1 with a thickness of approximately 2 mm. The laminated body 1 and a copper foil with a thickness of 18 μm were laminated and compressed under the same conditions to obtain a molded body 1.

[0267] [Example 1-2]

[0268] A molded body 2 was obtained in the same manner as in Example 1-1, except that F powder 12 was used instead of F powder 11.

[0269] [Examples 1-3]

[0270] Epoxy resin 1 (80 parts by mass) and surfactant A (20 parts by mass) were mixed, and a dispersion 12 was obtained by phase-transition emulsification. A molded body 3 was obtained in the same manner as in Example 1-1, except that dispersion 12 was used instead of dispersion 11.

[0271] 1-3. Evaluation

[0272] The appearance, peel strength, and water resistance of molded bodies 1 to 3 were evaluated according to the following criteria.

[0273] <Appearance of the molded body>

[0274] The surface of the molded body was observed visually and evaluated as follows.

[0275] ○ : No foaming is visible on the surface of the molded body, and it is smooth.

[0276] × : Foam is visible on the surface of the molded body, and it is not smooth.

[0277] <Peeling Strength of Molded Body>

[0278] A sample was prepared by cutting the molded body into a rectangular shape (length: 100 mm, width: 10 mm). Next, a position 50 mm from one end of the sample in the longitudinal direction was fixed, and the maximum load (N / cm) applied when the copper foil and the laminate were peeled off at a tensile speed of 50 mm / min and at a 90° angle relative to the sample from the end of the longitudinal direction was measured.

[0279] Based on the measured values, the peel strength was evaluated according to the following criteria.

[0280] ○ : 10 N / cm or more

[0281] × : Less than 10 N / cm

[0282] <Water Resistance of Molded Body>

[0283] The peel strength of the molded body after absorption was measured in the same manner as the above <Peeling Strength of Molded Body>, except that the sample was prepared after maintaining the molded body at 85°C and 85% relative humidity for 72 hours. For each molded body, the ratio of the peel strength of the molded body after absorption to the peel strength of the molded body measured in the above <Peeling Strength of Molded Body> was calculated and evaluated according to the following criteria.

[0284] ○ : 90% or more

[0285] × : Less than 90%

[0286] The evaluation results of molded bodies 1 to 3 are shown in Table 1.

[0287]

[0288] <Example 2>

[0289] 2-1. Preparation of Each Component

[0290] [F Powder]

[0291] F Powder 21: Powder comprising a polymer having polar functional groups containing TFE units, NAH units, and PPVE units in this order, at 97.9 mol%, 0.1 mol%, and 2.0 mol%, respectively (melting temperature 300 ℃, 5% weight loss temperature: 400 ℃ or higher) (D50: 25 µm)

[0292] F Powder 22: Powder (D50: 28 μm) comprising 97.5 mol% TFE units and 2.5 mol% PPVE units in this order, and a polymer (melting temperature 305 °C, 5% weight loss temperature: 400 °C or higher)

[0293] F Powder 23: Powder (D50: 2 μm) comprising 97.5 mol% TFE units and 2.5 mol% PPVE units in this order, and a polymer (melting temperature 305 °C, 5% weight loss temperature: 400 °C or higher)

[0294] In addition, the polymer of F powder 21 has carbonyl groups containing carbon atoms in the main chain, with 1 × 10 carbon atoms. 6 The polymers of F powder 22 and F powder 23, each containing 1000, do not have polar functional groups.

[0295] [Surfactant]

[0296] Surfactant 1: Polyoxyalkylene modified polydimethylsiloxane (Surface tension: 26 mN / m)

[0297] Surfactant 2: Polyoxyalkylene modified polyorganosiloxane (Surface tension: 30 mN / m)

[0298] [Liquid dispersion medium]

[0299] Water (Surface tension: 72 mN / m)

[0300] [write]

[0301] Material 1: Carbon fiber (Surface tension: 38 mN / m)

[0302] Material 2: Hydrophilic treated resin fiber (Surface tension: 25 mN / m)

[0303] 2-2. Preparation Example of Dispersion

[0304] [Example 2-1]

[0305] First, powder 21, surfactant 1, and water as a liquid dispersion medium were introduced into a pot, and zirconia balls were introduced. Then, the pot was rolled at 150 rpm for 1 hour to obtain a dispersion 21 (viscosity: 30 mPa·s) containing powder 21 (50 parts by mass), surfactant 1 (0.2 parts by mass), and water (49.8 parts by mass).

[0306] [Examples 2-2 to 2-6]

[0307] Dispersions 22 to 26 were prepared in the same manner as dispersion 21, except that the type of powder, surfactant, liquid dispersion medium, and amount of surfactant were changed as described in Table 2.

[0308] The components of dispersions 21 to 26 obtained above are summarized in Table 2. In addition, coating substrates were prepared using dispersions 21 to 26 by the following method and evaluated according to evaluation criteria. The results of evaluating the coating substrates obtained from each dispersion according to the following evaluation criteria are also summarized in Table 2.

[0309] 2-3. Example of manufacturing of a coating substrate

[0310] A dispersion 21 was applied to the surface of a long copper foil (thickness 18 μm) using a bar coater to form a wet film. Subsequently, the metal foil with the formed wet film was passed through a drying oven at 120 °C for 5 minutes to dry it by heating, and a dry film was obtained. Afterward, the dry film was heated in a nitrogen oven at 380 °C for 3 minutes. Thus, a coated substrate 1 was prepared having a polymer layer (thickness 5 μm) as a molded article comprising a metal foil and a molten sintered powder 21 on its surface.

[0311] Coating materials 2 through 6 were each manufactured in the same manner as coating material 1, except that dispersion 21 was changed to dispersions 22 through 26 respectively.

[0312] 2-4. Evaluation

[0313] 2-4-1. Evaluation of Dispersion Stability of Dispersions

[0314] After storing each dispersion in a container at 25°C, its dispersibility was visually checked, and dispersion stability was evaluated according to the following criteria.

[0315] [metewand]

[0316] ○ : The aggregate is not visible.

[0317] △ : Fine aggregates are observed adhering to the side walls of the container. When lightly stirred, they were uniformly redispersed.

[0318] × : It is visible that aggregates have settled at the bottom of the container. When shearing is applied and stirring is performed, they are uniformly redispersed.

[0319] 2-4-2. Evaluation of Component Sedimentation Rate

[0320] Each dispersion (18 mL) was placed in a screw tube (inner volume: 30 mL) and left to stand at 25°C for 14 days. The component sedimentation rate was calculated according to the following formula based on the height of the entire dispersion and the height of the sedimentation layer (dispersion layer) inside the screw tube before and after standing. Additionally, if no sedimentation layer was observed after standing and there was no change in the state, it was assumed that there was no change in the height of the entire dispersion, and the component sedimentation rate was set to 100%.

[0321] Component Sedimentation Rate (%) = (Height of Sedimentation Layer) / (Height of Total Dispersion) × 100

[0322] [metewand]

[0323] ○ : The sedimentation rate of the component measured by the above method is 70% or higher.

[0324] △ : The component sedimentation rate measured by the above method is less than 70% and greater than or equal to 60%.

[0325] × : The component sedimentation rate measured by the above method is less than 60%.

[0326] 2-4-3. Evaluation of Surface Coating Condition of Coated Substrate

[0327] For each coating substrate, the surface smoothness was visually inspected, and the surface smoothness was evaluated according to the following criteria.

[0328] [metewand]

[0329] ○ : The entire surface of the polymer layer is smooth.

[0330] △ : Unevenness caused by the absence of aggregates or powder is visible at the edges of the surface of the polymer layer.

[0331] × : Unevenness caused by aggregation or powder defects is visible across the entire surface of the polymer layer.

[0332]

[0333] Industrial applicability

[0334] The sizing agent, the sizing-treated fiber, and the prepreg formed from the fiber of the present invention can suppress foaming during heat molding, thereby enabling the formation of a molded product with excellent appearance such as smoothness, and particularly excellent adhesion and water resistance when formed into a laminate. The resulting molded product can be preferably used in many fields such as printed circuit boards, aircraft components, spacecraft components, automobile components, ship components, civil engineering and construction materials, oil drilling components, hydrogen tanks, hydrogen tank pressure vessels, wind turbine blades, and sports equipment.

[0335] In addition, as can be seen from the above results, the dispersion (2) has excellent dispersibility and dispersion stability. Also, the surface of the coated substrate formed from the dispersion (2) has excellent uniformity and excellent appearance. Therefore, it is thought that the coated substrate obtained by coating the substrate with the dispersion (2) highly exhibits the properties of the F polymer. In addition, it is thought that when the dispersion (2) is used as a sizing agent, a sizing effect is obtained. The prepreg containing fibers and matrix resin sized by the dispersion (2) is thought to have excellent mechanical properties.

[0336] In addition, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2020-118558 filed on July 9, 2020 and Japanese Patent Application No. 2020-148433 filed on September 3, 2020 are incorporated herein by reference and accepted as disclosure of the specification of the present invention.

Claims

Claim 1 A sizing agent comprising a dispersion, wherein the dispersion comprises a powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 10 to 100 μm, a surfactant, and a liquid dispersion medium, wherein the content of the surfactant is 0.01 parts by mass or less per 1 part by mass of the tetrafluoroethylene-based polymer powder. Claim 2 A sizing agent according to claim 1, wherein the melting temperature of the tetrafluoroethylene-based polymer is 280 to 325 ℃. Claim 3 A sizing agent according to claim 1 or 2, wherein the 5% weight reduction temperature of the tetrafluoroethylene-based polymer is 360°C or higher. Claim 4 A sizing agent according to claim 1 or 2, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a perfluoro(alkyl vinyl ether)-based unit and a polar functional group, or a tetrafluoroethylene-based polymer having 2.0 to 5.0 mol% of a perfluoro(alkyl vinyl ether)-based unit with respect to the total unit and not having a polar functional group. Claim 5 In claim 4, the tetrafluoroethylene-based polymer having the polar functional group is a tetrafluoroethylene-based polymer having a carbonyl group containing group, and the number of carbonyl group containing groups is 1 × 10 Cs per carbon atom of the main chain 6 10 to 5,000 individuals per unit, sizing agent. Claim 6 Fiber sized with the sizing agent described in claim 1, having a heat-meltable tetrafluoroethylene-based polymer attached to the surface. Claim 7 A sizing-treated fiber according to claim 6, wherein the amount of the tetrafluoroethylene-based polymer attached is 0.1 to 10 parts by mass per 100 parts by mass of the fiber. Claim 8 A prepreg containing a sizing-treated fiber as described in claim 6 or 7, and a matrix resin. Claim 9 A dispersion comprising a powder of a heat-meltable tetrafluoroethylene-based polymer having an average particle size of 10 to 100 μm, a surfactant, and a liquid dispersion medium, wherein the content of the surfactant is 0.01 parts by mass or less per 1 part by mass of the tetrafluoroethylene-based polymer powder. Claim 10 In claim 9, a dispersion in which the surface tension of the surfactant is 28 mN / m or less. Claim 11 In claim 9, the dispersion wherein the surfactant is a silicone-based surfactant, a fluorine-based surfactant, a glycol-based surfactant, or an alkylamide ether-based surfactant. Claim 12 A dispersion according to claim 9, wherein the content of the tetrafluoroethylene-based polymer is 25 to 60 parts by mass per 100 parts by mass of the liquid dispersion medium. Claim 13 A sizing agent comprising a dispersion described in any one of claims 10 to 12. Claim 14 delete Claim 15 delete

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