Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
  • C08J3/05—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media from solid polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08L27/18—Homopolymers or copolymers or tetrafluoroethene

Definitions

• the present invention relates to a method for storing a container for a dispersion liquid containing tetrafluoroethylene-based polymer particles, and to a dispersion liquid container.
• tetrafluoroethylene-based polymers which have low dielectric constants and low dielectric loss tangents, have been attracting attention as insulating layer materials for printed circuit boards of communication devices.
• an aqueous dispersion containing particles of a tetrafluoroethylene-based polymer is known as a material for forming an insulating layer containing such a polymer.
• aqueous dispersions are highly versatile in terms of the equipment required for their use and have a high selectivity for substrates to be coated, etc., their liquid properties are often insufficient, and improvements to the liquid properties are being investigated.
• Patent Document 1 proposes an aqueous PTFE dispersion that contains a specified amount of an emulsion polymerization liquid of polytetrafluoroethylene (PTFE) fine particles having a specific particle size and a dispersant, and has a foam volume ratio less than a specific amount.
• PTFE polytetrafluoroethylene
• the present inventors have found that, when the liquid density of a dispersion containing tetrafluoroethylene-based polymer particles and water is adjusted to a specific range and stored in a storage container, and the product of the gas phase volume ratio in the storage container and the gas-liquid interface area of the storage container is kept within a specific range and stored at a specific temperature, the deterioration of the tetrafluoroethylene-based polymer and the coloring of the dispersion are suppressed. Then, they have found that the molded product such as a polymer layer formed from the dispersion stored by such a storage method has excellent physical properties such as heat resistance and electrical properties (low linear expansion coefficient, low dielectric constant and low dielectric tangent) based on the tetrafluoroethylene-based polymer, has little coloring, is suppressed from foaming, and has excellent surface appearance, and have arrived at the present invention.
• An object of the present invention is to provide a method for storing a dispersion liquid container in which a dispersion liquid containing tetrafluoroethylene-based polymer particles and water is contained in a storage container, and the dispersion liquid container is capable of suppressing deterioration of the tetrafluoroethylene-based polymer and coloration of the dispersion liquid.
• a method for storing a dispersion liquid container comprising: storing a dispersion liquid containing particles of a tetrafluoroethylene-based polymer, a nonionic surfactant, and water in a container such that the liquid density of the dispersion liquid is in the range of 95.0% or more and less than 99.9% of the theoretical liquid density of the dispersion liquid calculated by the following formula (1), to obtain a dispersion liquid container; and storing the dispersion liquid container while maintaining the product of a gas phase volume ratio in the container and a gas-liquid interface area of the container in the range of 10,000 or more and 60,000 or less, and maintaining a temperature in the range of more than 0° C. and 20° C.
• Theoretical liquid density of dispersion (density of dispersoid ⁇ volume ratio of dispersoid)/(density of dispersoid ⁇ volume ratio of dispersoid+density of dispersion medium ⁇ volume ratio of dispersion medium) (1)
• the storage method according to [1] wherein the tetrafluoroethylene-based polymer is heat-fusible and contains an oxygen-containing polar group.
• a dispersion container in which a dispersion containing tetrafluoroethylene-based polymer particles, a nonionic surfactant, and water is contained in a container, the liquid density of the dispersion being in the range of 95.0% or more and less than 99.9% of the theoretical liquid density of the dispersion calculated by the following formula (1), and the product of the gas phase volume ratio in the container and the gas-liquid interface area of the container being in the range of 10,000 or more and 60,000 or less.
• Theoretical liquid density of dispersion (density of dispersoid ⁇ volume ratio of dispersoid)/(density of dispersoid ⁇ volume ratio of dispersoid+density of dispersion medium ⁇ volume ratio of dispersion medium) (1)
• the dispersion container according to [11] wherein the tetrafluoroethylene-based polymer is heat-fusible and contains an oxygen-containing polar group.
• the present invention provides a method for storing a dispersion container in which a dispersion containing tetrafluoroethylene-based polymer particles and water is stored in a container, and the dispersion container is capable of suppressing deterioration of the tetrafluoroethylene-based polymer and coloring of the dispersion.
• a molded product such as a coating film that has excellent physical properties based on the tetrafluoroethylene-based polymer, such as heat resistance and electrical properties (low linear expansion coefficient, low dielectric constant, and low dielectric tangent), has little coloring, is suppressed in foaming, and has excellent surface appearance, specifically, a laminate having a polymer layer formed from the dispersion, can be formed.
• the "average particle size (D50)" is the volume-based cumulative 50% diameter of a particle or filler determined by a laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, a cumulative curve is calculated with the total volume of the particle group as 100%, and the average particle size (D50) is the particle size at the point on the cumulative curve where the cumulative volume is 50%.
• the D50 of a particle or filler can be determined by dispersing the particles in water and analyzing them by a laser diffraction/scattering method using a laser diffraction/scattering type particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.).
• Average particle size (D90) is the volume-based cumulative 90% diameter of particles, which is determined in the same manner as D50.
• the specific surface area of a particle or filler is a value calculated by measuring the particle by a gas adsorption (constant volume method) BET multipoint method, and is determined using a NOVA4200e (manufactured by Quantachrome Instruments).
• Melting temperature is the temperature corresponding to the maximum of the melting peak of a polymer as measured by differential scanning calorimetry (DSC).
• DSC differential scanning calorimetry
• glass transition temperature (Tg)” is a value measured by analyzing a polymer using a dynamic mechanical analysis (DMA) method.
• the "viscosity” is determined by measuring the composition using a Brookfield viscometer at 25° C. and a rotation speed of 30 rpm. The measurement is repeated three times, and the average value of the three measured values is calculated.
• the "thixotropy ratio” is a value calculated by dividing the viscosity ⁇ 1 of the composition measured at a rotation speed of 30 rpm by the viscosity ⁇ 2 measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average value of the three measured values is used.
• the "HLB (Hydrophilic-Lipophilic Balance) value" of a surfactant is a value defined by the following calculation formula (Griffin formula) according to the Griffin method.
• the unit may be a unit formed directly by a polymerization reaction, or may be a unit in which a part of the unit is converted into a different structure by processing the polymer.
• a unit based on monomer a is also simply referred to as "monomer a unit”.
• the storage method of the present invention is a method for storing a dispersion liquid containing particles (hereinafter also referred to as "F particles”) of a tetrafluoroethylene polymer (hereinafter also referred to as “F polymer”), a nonionic surfactant, and water (hereinafter also referred to as “this dispersion liquid”), which is stored in a storage container with a liquid density of the dispersion liquid in the range of 95.0% or more and less than 99.9% of the theoretical liquid density of the dispersion liquid calculated by the following formula (1), to form a dispersion liquid container (hereinafter also referred to as "this container”), and which is stored while maintaining the product of the gas phase volume ratio (unit: volume %) in the storage container and the gas-liquid interface area (unit: cm2 ) of the storage container in the range of 10,000 or more and 60,000 or less, and maintaining the temperature in the range of more than 0°C and 20°C or less
• Theoretical liquid density of dispersion (density of dispersoid ⁇ volume ratio of dispersoid)/(density of dispersoid ⁇ volume ratio of dispersoid+density of dispersion medium ⁇ volume ratio of dispersion medium) (1)
• the term "dispersoid” in the formula refers to a component that disperses without dissolving in a dispersion medium, such as F particles, among the components of the dispersion liquid described below
• the term “dispersion medium” refers to a liquid dispersion medium, such as water, and a component that dissolves in the liquid dispersion medium.
• the deterioration of the F polymer in the dispersion and the coloring of the dispersion can be suppressed for a long period of time.
• the dispersion to which this method is applied can be used to form a molded product such as a coating film that has excellent physical properties based on the F polymer, such as heat resistance and electrical properties (low linear expansion coefficient, low dielectric constant and low dielectric tangent), little coloring, and foaming suppression, and is also excellent in adhesion and surface appearance, specifically, a laminate having a polymer layer formed from the dispersion.
• excellent surface appearance includes both excellent surface smoothness such as “less surface roughness” and excellent appearance observed visually or with an analytical instrument such as "no streaks, cracks, defects, etc. on the surface”.
• the nonionic surfactant contained in the present dispersion not only adheres to the F particles to improve their dispersibility in liquid, but also forms a Langmuir film-like coating at the interface between the gas phase in the container and the liquid phase of the present dispersion when the present dispersion is contained in a container to form a container.
• the present dispersion can be considered to be in a state in which it incorporates and contains a small amount of bubbles.
• the nonionic surfactant is thought to easily balance the gas-liquid equilibrium in the present container. Due to such gas-liquid equilibrium, the amount of dissolved oxygen in the dispersion is constant in the container, and it is believed that the sterilizing and bleaching effects due to the radicalization and ionization of oxygen are likely to be enhanced, and it is presumed that the hue of the dispersion is stable even when stored for a long period of time. On the other hand, since the storage is performed at a low temperature within a specified temperature range in this method, it is believed that the alteration and deterioration of the F polymer due to oxygen is easily suppressed.
• the content of each of the F particles, the nonionic surfactant, and the water relative to the total content of the F particles, the nonionic surfactant, and the water in the present dispersion is within a specified range, and the amount of dissolved oxygen in the present dispersion is within a specified range, deterioration and coloration of the F polymer in the present dispersion is more easily suppressed even after long-term storage.
• the F polymer which is a constituent of the present dispersion, is a polymer containing units (hereinafter also referred to as "TFE units") based on tetrafluoroethylene (hereinafter also referred to as "TFE").
• the F polymer may be either heat-fusible or non-heat-fusible.
• a heat-fusible polymer means a polymer that has a temperature at which the melt flow rate is 1 to 1000 g/10 min under a load of 49 N.
• the melting temperature of the F polymer, which is heat-fusible is preferably 180° C. or higher, more preferably 200° C. or higher.
• the melting temperature of the F polymer is preferably 325° C. or lower, more preferably 320° C. or lower.
• a molded product such as a coating film (polymer layer) formed from the present dispersion by applying the present method is likely to have excellent heat resistance.
• the glass transition point of the F polymer is preferably 50° C. or higher, more preferably 75° C. or higher.
• the glass transition point of the F polymer is preferably 150° C. or lower, more preferably 125° C. or lower.
• the fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass.
• the surface tension of the F polymer is preferably 16 to 26 mN/m.
• the surface tension of the F polymer can be measured by placing a droplet of a mixture for wetting tension testing (manufactured by Wako Pure Chemical Industries, Ltd.) specified in JIS K 6768 on a flat plate made of the F polymer.
• F polymer is preferably polytetrafluoroethylene (PTFE), the polymer that comprises TFE unit and ethylene-based unit (ETFE), the polymer that comprises TFE unit and propylene-based unit, the polymer that comprises TFE unit and perfluoro(alkyl vinyl ether) (PAVE)-based unit (PAVE unit) (PFA), the polymer that comprises TFE unit and hexafluoropropylene-based unit (FEP), more preferably PFA and FEP, and even more preferably PFA.
• PTFE include low molecular weight PTFE and modified PTFE.
• PAVE is preferably CF 2 ⁇ CFOCF 3 , CF 2 ⁇ CFOCF 2 CF 3 or CF 2 ⁇ CFOCF 2 CF 2 CF 3 (hereinafter also referred to as “PPVE”), and more preferably PPVE.
• F polymer preferably has an oxygen-containing polar group, more preferably has a hydroxyl group-containing group or a carbonyl group-containing group, and even more preferably has a carbonyl group-containing group.
• the dispersion liquid applied with this method is likely to have excellent dispersion stability and handling.
• the molded product such as a coating film (polymer layer) formed from such dispersion liquid is likely to have excellent physical properties such as heat resistance, electrical properties (low linear expansion coefficient, low dielectric constant and low dielectric tangent), and its surface appearance.
• the hydroxyl-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably --CF 2 CH 2 OH or --C(CF 3 ) 2 OH.
• the carbonyl group-containing group is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH 2 ), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.) or a carbonate group (-OC(O)O-), and more preferably an acid anhydride residue.
• the number of oxygen-containing polar groups in the F polymer is preferably 10 to 5000, more preferably 100 to 3000, per 1 ⁇ 10 6 carbon atoms in the main chain.
• the number of oxygen-containing polar groups in the F polymer can be quantified by the composition of the polymer or the method described in WO 2020/145133.
• the oxygen-containing polar group may be contained in a unit based on a monomer in the F polymer, or may be contained in a terminal group of the main chain of the F polymer, with the former being preferred.
• Examples of the latter include F polymers having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and F polymers obtained by subjecting F polymers to plasma treatment or ionizing radiation treatment.
• the F polymer is preferably a polymer having a carbonyl group-containing group including TFE units and PAVE units, more preferably a polymer including TFE units, PAVE units, and units based on a monomer having a carbonyl group-containing group, and more preferably a polymer including these units in this order in an amount of 90 to 99 mol%, 0.99 to 9.97 mol%, and 0.01 to 3 mol% based on all units.
• Specific examples of such F polymers include the polymers described in WO 2018/016644.
• the monomer having a carbonyl group-containing group is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"), and more preferably NAH.
• the D50 of the F particles is preferably 1 ⁇ m or more and less than 10 ⁇ m.
• the F particles may be solid particles or non-hollow particles.
• the F particles may be secondary particles formed from nanometer-order fine particles.
• the D50 of the F particles is preferably 1.0 ⁇ m or more, and more preferably 1.5 ⁇ m or more.
• the D50 of the F particles is preferably 6 ⁇ m or less, and more preferably 5 ⁇ m or less.
• D90 of the F particles is preferably 8 ⁇ m or less, and more preferably 6 ⁇ m or less.
• the specific surface area of the F particles is preferably 1 to 25 m 2 /g, and more preferably 6 to 15 m 2 /g.
• the dispersion tends to have excellent dispersion stability and ease of handling, and the molded product such as a coating film (polymer layer) formed from such a dispersion tends to have excellent physical properties such as heat resistance and electrical properties (low linear expansion coefficient, low dielectric constant and low dielectric tangent) and excellent surface appearance.
• the F particles are particles containing an F polymer, and preferably consist of an F polymer.
• the F particles are more preferably particles of a heat-fusible F polymer having an oxygen-containing polar group and a melting temperature of 200 to 325° C. In this case, the above-mentioned mechanism of action is more effectively exerted and aggregation of the F particles is more easily suppressed.
• the F particles may contain a resin or an inorganic compound other than the F polymer, may form a core-shell structure with an F polymer as the core and a resin other than the F polymer or an inorganic compound as the shell, or may form a core-shell structure with an F polymer as the shell and a resin other than the F polymer or an inorganic compound as the core.
• examples of the resin other than the F polymer include aromatic polyester, polyamideimide, polyimide, and maleimide
• examples of the inorganic compound include silica and boron nitride.
• the F particles may be used alone or in combination of two or more kinds.
• the F particles may be used in combination with particles of a non-thermofusible tetrafluoroethylene polymer.
• particles of a heat-fusible F polymer having a melting temperature of 200 to 325°C are preferred, particles of a heat-fusible F polymer having a melting temperature of 200 to 325°C and having an oxygen-containing polar group are more preferred, and as particles of a non-thermofusible tetrafluoroethylene polymer, particles of non-thermofusible PTFE are preferred.
• the aggregation suppression effect of the particles of the heat-fusible F polymer and the retention effect of the fibrillation of the non-thermofusible tetrafluoroethylene polymer are balanced, and the dispersibility of the present dispersion to which the present method is applied is easily improved.
• the electrical properties of the non-thermofusible tetrafluoroethylene polymer are easily expressed to a high degree.
• the content of F particles in this dispersion is preferably 25% by mass or more, and more preferably 35% by mass or more.
• the content of F particles is preferably 75% by mass or less, and more preferably 70% by mass or less.
• nonionic surfactant examples include glycol surfactants, acetylene surfactants, fluorine surfactants, and silicone surfactants.
• silicone surfactants and acetylene diol surfactants are preferred.
• the silicone surfactant a polyoxyalkylene-modified dimethylsiloxane having a polyoxyalkylene structure as a hydrophilic portion and a polydimethylsiloxane structure as a hydrophobic portion is more preferable.
• the polyoxyalkylene-modified dimethylsiloxane may have a polydimethylsiloxane unit (-( CH3 ) 2SiO2 /2- ) in the main chain, may have a polydimethylsiloxane unit in the side chain, or may have a polydimethylsiloxane unit in both the main chain and the side chain.
• the polyoxyalkylene-modified polydimethylsiloxane is preferably a polyoxyalkylene-modified polydimethylsiloxane containing a dimethylsiloxane unit in the main chain and an oxyalkylene group in the side chain, or a polyoxyalkylene-modified polydimethylsiloxane containing a dimethylsiloxane unit in the main chain and an oxyalkylene group at a main chain terminal.
• the oxyalkylene group contained in the polyoxyalkylene-modified dimethylsiloxane may be composed of only one type of oxyalkylene group, or may be composed of two or more types of oxyalkylene groups.
• silicone surfactants include "BYK-347”, “BYK-349”, “BYK-378”, “BYK-3450”, “BYK-3451”, “BYK-3455”, and “BYK-3456” (manufactured by BYK Japan KK), and "KF-6011” and “KF-6043” (manufactured by Shin-Etsu Chemical Co., Ltd.).
• Acetylene diol surfactants are surfactants having a carbon-carbon triple bond in the molecule, and examples of such surfactants include acetylene diol (having an acetylene bond and two hydroxyl groups in the same molecule) surfactants and surfactants in which an alkylene oxide such as ethylene oxide or propylene oxide is added to an acetylenic diol.
• acetylene diol surfactants examples include the "Surfynol (registered trademark)” series and the “Olfine (registered trademark)” series (both manufactured by Nissin Chemical Industry Co., Ltd.); and the “Acetylenol (registered trademark)” series (manufactured by Kawaken Fine Chemicals Co., Ltd.).
• the HLB value of the nonionic surfactant calculated from the Griffin formula is preferably 1 to 18, more preferably 3 or more, more preferably 6 or more, and even more preferably 10 or more.
• the HLB value is preferably 16 or less, and even more preferably 15 or less.
• the HLB value of the nonionic surfactant is preferably 3 to 16, more preferably 8 to 15, and even more preferably 10 to 15.
• the molded product such as a coating film obtained from the present dispersion by applying the present method is less colored, foaming is suppressed, and adhesion and surface appearance are more easily excellent. Furthermore, the uniform fluidity of the present dispersion is more easily maintained after long-term storage, and recovery from a storage container is more easily improved.
• the nonionic surfactant may be used alone or in combination of two or more kinds.
• the mass ratio of the content of the nonionic surfactant to the F particles in the dispersion is preferably 0.01 to 0.15, and more preferably in the range of 0.03 to 0.1.
• the mass ratio of the content of the nonionic surfactant to the F particles is in the above-mentioned range, the above-mentioned mechanism of action is more easily expressed.
• the water constituting the present dispersion serves as a dispersion medium.
• a dispersion medium a small amount of a dispersion medium other than water may be contained as long as the effect of the present method is exhibited.
• a dispersion medium is preferably miscible with water, and is preferably at least one selected from the group consisting of amides, ketones, and esters.
• amide examples include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropanamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-diethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone.
• ketone examples include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, and cycloheptanone.
• ester examples include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl 3-ethoxypropionate, ⁇ -butyrolactone, and ⁇ -valerolactone. These may be used alone or in combination of two or more.
• the respective contents of F particles, nonionic surfactant, and water in the dispersion liquid relative to the total of F particles, nonionic surfactant, and water are preferably 35 to 70 mass%, 1 to 15 mass%, and 15 to 64 mass%, respectively.
• the contents of each component are within the above-mentioned ranges, the above-mentioned mechanism of action is more easily manifested, and coloration of the dispersion liquid is more easily suppressed even after long-term storage.
• the present dispersion may further contain an inorganic filler.
• an inorganic filler such as a coating film formed from the present dispersion is likely to have excellent electrical properties and low linear expansion.
• the shape of the inorganic filler may be any of spherical, acicular (fibrous), and plate-like, and specifically may be spherical, scaly, lamellar, leaflet-like, apricot kernel-like, columnar, cockscomb-like, equiaxed, leaf-like, micaceous, block-like, flat, wedge-like, rosette-like, net-like, and prismatic.
• inorganic fillers include silicon compounds such as quartz powder, silica, wollastonite, talc, silicon nitride, silicon carbide, and mica; nitrogen compounds such as boron nitride and aluminum nitride; metal oxides such as aluminum oxide, zinc oxide, titanium oxide, cerium oxide, beryllium oxide, magnesium oxide, nickel oxide, vanadium oxide, copper oxide, iron oxide, and silver oxide; carbon fibers; carbon allotropes such as graphite, graphene, and carbon nanotubes; and metals such as silver and copper.
• One type of inorganic filler may be used, or two or more types may be used in combination.
• the D50 of the inorganic filler is preferably 0.1 to 50 ⁇ m.
• the surface of the inorganic filler may be treated with a silane coupling agent.
• the dispersion may further contain an aromatic polymer.
• an aromatic polymer may be contained as a non-hollow particle, or may be dissolved or dispersed in a liquid dispersion medium such as water constituting the dispersion, or other dispersion medium contained as necessary (hereinafter, water, other dispersion medium, etc. are collectively referred to as "liquid dispersion medium").
• aromatic polymer examples include polyester resins such as liquid crystalline aromatic polyesters, polyimide resins, polyamideimide resins, epoxy resins, maleimide resins, urethane resins, polyphenylene ether resins, polyphenylene oxide resins, and polyphenylene sulfide resins.
• polyester resins such as liquid crystalline aromatic polyesters, polyimide resins, polyamideimide resins, epoxy resins, maleimide resins, urethane resins, polyphenylene ether resins, polyphenylene oxide resins, and polyphenylene sulfide resins.
• aromatic imide polymer selected from the group consisting of aromatic polyimides, aromatic polyamic acids, aromatic polyamideimides, and precursors of aromatic polyamideimides is more preferred.
• the aromatic polymer is preferably contained as a varnish dissolved in a liquid dispersion medium.
• aromatic imide polymers include the "UPIA-AT” series (UBE), the “NEOPLIM (registered trademark)” series (Mitsubishi Gas Chemical Company, Inc.), the “SPIXELIA (registered trademark)” series (Somar), the “Q-PILON (registered trademark)” series (PI Technical Research Institute), the "WINGO” series (Wingo Technology Co., Ltd.), the “TOMAID (registered trademark)” series (T&K TOKA Corporation), the "KPI-MX” series (Kawamura Sangyo Co., Ltd.), “HPC-1000” and “HPC-2100D” (both manufactured by Showa Denko Materials K.K.).
• the content of the aromatic polymer relative to the F particles is preferably 1 to 25% by mass.
• the dispersion may further contain various additives such as thixotropic agents, viscosity regulators, defoamers, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, and flame retardants.
• additives such as thixotropic agents, viscosity regulators, defoamers, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, and flame retardants.
• the amount of dissolved oxygen in the dispersion is preferably in the range of 8 to 12 ppm.
• the amount of dissolved oxygen in the dispersion in the container tends to be constant due to the gas-liquid equilibrium balance in the above-mentioned mechanism of action, and the effects of the present invention are more easily achieved.
• the viscosity of the present dispersion is preferably 10 mPa ⁇ s or more, more preferably 100 mPa ⁇ s or more.
• the viscosity of the present dispersion is preferably 10,000 mPa ⁇ s or less, more preferably 3,000 mPa ⁇ s or less.
• the present dispersion has excellent coatability and is easy to form a molded product such as a coating film (polymer layer) having a desired thickness.
• the present dispersion having a viscosity in this range is easy to highly express the physical properties of the F polymer in the molded product formed therefrom.
• the thixotropy ratio of the present dispersion is preferably 1.0 to 2.5, in which case the present dispersion has excellent coatability and homogeneity, and is likely to produce a denser molded product.
• the pH of the dispersion is more preferably 8 to 10 from the viewpoint of improving long-term storage stability.
• the pH of such a dispersion can be adjusted with a pH adjuster (amine, ammonia, citric acid, etc.) or a pH buffer (tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium hydrogen carbonate, ammonium carbonate, ammonium acetate, etc.).
• the present dispersion liquid can be obtained by mixing F particles, a nonionic surfactant, water, and, if necessary, the above-mentioned other dispersion medium, inorganic filler, aromatic polymer, additives, etc.
• the dispersion may be obtained by mixing the F particles, the nonionic surfactant, and the water all at once, or may be mixed separately in sequence, or a master batch of these may be prepared in advance and then mixed with the remaining components. There is no particular restriction on the order of mixing, and the mixing method may be either mixing all at once or mixing in several separate batches.
• the F particles preliminarily disperse the F particles in a portion of the water, then add and mix a nonionic surfactant, and add the resulting mixture to the remaining water to obtain the present dispersion, from the viewpoint of easily improving the dispersion stability of the F particles.
• the nonionic surfactant may be added as it is or as an aqueous solution.
• the above-mentioned other dispersion medium, inorganic filler, aromatic polymer, additive, etc. are further mixed as necessary, they may be mixed at once when mixing the F particles and water, or each component may be added and mixed sequentially, or the mixture of the F particles, water, and the nonionic surfactant may be mixed when adding it to water.
• the dispersion liquid to which the present method is applied is preferably prepared by mixing an F polymer powder, a nonionic surfactant, and water.
• the F polymer powder is an aggregate of F particles, and may be an aggregate of F particles themselves or an aggregate of some of the F particles aggregated.
• the powder of F polymer is preferably obtained by radically polymerizing TFE and other monomers in a polymerization medium to produce F polymer, removing the polymerization medium to recover granular F polymer, mechanically pulverizing the polymer with a jet mill or the like, and further classifying the polymer as necessary.
• F polymer powder may also be used as a commercially available product, PFA powder (FluonPFA P-62X, FluonPFA P-63, etc., both manufactured by AGC) or ETFE powder, which is a powder formed from a heat-fusible fluorine-containing copolymer obtained by radical polymerization in a polymerization medium.
• Mixing equipment for obtaining this dispersion includes blade-equipped stirring equipment such as a Henschel mixer, pressure kneader, Banbury mixer, and planetary mixer, media-equipped grinding equipment such as a ball mill, attritor, basket mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC Mill, spike mill, and agitator mill, and dispersing equipment equipped with other mechanisms such as a microfluidizer, nanomizer, 8%, ultrasonic homogenizer, dissolver, disperser, high-speed impeller, thin film swirling high-speed mixer, centrifugal mixer, and V-type mixer.
• blade-equipped stirring equipment such as a Henschel mixer, pressure kneader, Banbury mixer, and planetary mixer
• media-equipped grinding equipment such as a ball mill, attritor, basket mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC Mill, spike mill, and agitator mill
• the dispersion is stored in a container having a liquid density in the range of 95.0% or more and less than 99.9% of the theoretical liquid density of the dispersion calculated by the following formula (1) to form a dispersion container.
• Theoretical liquid density of dispersion (density of dispersoid ⁇ volume ratio of dispersoid)/(density of dispersoid ⁇ volume ratio of dispersoid+density of dispersion medium ⁇ volume ratio of dispersion medium) (1)
• the means for adjusting the liquid density of the present dispersion to the above range with respect to the theoretical liquid density include stirring treatment with a homodisper, defoaming treatment with a vacuum defoamer, foam adjustment treatment with a defoamer, etc.
• the liquid density of the present dispersion can be measured using a Gay-Lussac type pycnometer by the procedure described in the Examples below.
• the product of the gas phase volume ratio (unit: volume %) in the container and the gas-liquid interface area (unit: cm2 ) of the container is 10,000 or more.
• the product is 60,000 or less, preferably 40,000 or less, and more preferably 20,000 or less.
• the temperature of the dispersion container is maintained within a range of more than 0°C and not more than 20°C during storage.
• a container As the container, metal containers such as drums, pails, and 18 liter cans, which are commonly used as containers for storing and transporting chemicals, can be used. From the viewpoint of more advanced storage management, a container may be used in which the material of the inside of the container that comes into contact with the present dispersion is non-metallic.
• a container may be a container made of a single layer of a resin such as polyolefin, ceramics, glass, etc., which has excellent water resistance and chemical resistance, or a laminated container having these as the innermost layer.
• the dielectric constant of the molded product formed from the dispersion liquid using this method is preferably greater than 1.0 and less than 2.4.
• the dielectric tangent of the molded product is preferably greater than 0.0010 and less than 0.0022.
• the thermal conductivity of the molded product is preferably greater than 1 W/m ⁇ K.
• a molded product such as a sheet containing the F polymer can be formed.
• the sheet obtained by extrusion may be further cast by press molding, calendar molding, etc.
• the sheet is preferably further heated to remove the liquid dispersion medium and to bake the F polymer.
• the thickness of the sheet formed from the dispersion liquid by applying the present method is preferably 1 to 1000 ⁇ m.
• the suitable ranges of the dielectric constant, dielectric loss tangent and thermal conductivity of the sheet are the same as the ranges of the dielectric constant, dielectric loss tangent and thermal conductivity of the molded product described above.
• the thermal conductivity of the sheet means the thermal conductivity in the in-plane direction of the sheet.
• the linear expansion coefficient of the sheet is preferably 10 to 100 ppm/°C.
• a laminate can be formed by laminating such a sheet on a substrate.
• methods for producing a laminate include a method of extruding the present dispersion onto the substrate, and a method of thermocompression bonding the sheet and the substrate.
• the substrate include metal substrates such as metal foils of copper, nickel, aluminum, titanium, alloys thereof, etc.; films of heat-resistant resins such as polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyaryl ether ketone, polyamideimide, liquid crystalline polyester, and tetrafluoroethylene polymers; prepreg substrates (precursors of fiber-reinforced resin substrates), ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride; and glass substrates.
• the shape of the substrate may be flat, curved, or uneven, and may be any of a foil, plate, film, and fiber shape.
• the ten-point average roughness of the surface of the substrate is preferably 0.01 to 0.05 ⁇ m.
• the surface of the substrate may be treated with a silane coupling agent.
• the peel strength between the sheet and the substrate is preferably 10 to 100 N/cm or more.
• a laminate having a substrate layer composed of the substrate and an F layer in this order can be obtained.
• the F layer is preferably formed by disposing the present dispersion applied by the present method on the surface of a substrate, heating to remove the liquid dispersion medium, and further heating to bake the F polymer. By separating the substrate from such a laminate, a sheet containing the F polymer can be obtained.
• the substrate may be the same as the substrate that can be laminated with the above-mentioned sheet, and the preferred embodiments thereof are also the same.
• the method for disposing the present dispersion using this method includes a coating method, a droplet discharging method, and a dipping method, and is preferably a roll coating method, a knife coating method, a bar coating method, a die coating method, or a spray method.
• Heating for removing the liquid dispersion medium is preferably performed at 100 to 200° C. for 0.1 to 30 minutes.
• the heating for baking the F polymer is preferably carried out at a temperature equal to or higher than the baking temperature of the F polymer, more preferably at 360 to 400° C. for 0.1 to 30 minutes.
• the heating device for each heating may be an oven or a ventilated drying furnace.
• the heat source in the device may be a contact type heat source (hot air, hot plate, etc.) or a non-contact type heat source (infrared rays, etc.).
• the heating may be carried out under normal pressure or under reduced pressure.
• the atmosphere in each heating step may be either an air atmosphere or an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.).
• the F layer is formed through the steps of disposing the present dispersion to which the present method is applied and heating. These steps may be performed once each, or may be repeated two or more times.
• the present dispersion to which the present method is applied may be disposed on the surface of a substrate, heated to form an F layer, and the present dispersion to which the present method is applied may be disposed on the surface of the F layer and heated to form a second F layer.
• the present dispersion to which the present method is applied may be disposed on the surface of a substrate, heated to remove the liquid dispersion medium, and then the present dispersion to which the present method is applied may be disposed on the surface of the substrate, heated to form an F layer.
• the dispersion applied by this method may be disposed on only one surface of the substrate, or on both surfaces of the substrate.
• a laminate having a substrate layer and an F layer on one surface of the substrate layer is obtained, and in the latter case, a laminate having a substrate layer and an F layer on both surfaces of the substrate layer is obtained.
• Suitable specific examples of the laminate include a metal-clad laminate having a metal foil and an F layer on at least one surface of the metal foil, and a multilayer film having a polyimide film and an F layer on both surfaces of the polyimide film.
• the preferred ranges of the dielectric constant, dielectric dissipation factor, thermal conductivity, linear expansion coefficient, and peel strength between the F layer and the substrate layer of the F layer are the same as the preferred ranges of the dielectric constant, dielectric dissipation factor, thermal conductivity, linear expansion coefficient, and peel strength between the sheet and the substrate of the sheet formed from the above-mentioned dispersion.
• the dispersion obtained by this method is useful as a material for imparting insulating properties, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity.
• the dispersion to which this method is applied can be used in printed wiring boards, thermal interface materials, substrates for power modules, coils used in power devices such as motors, in-vehicle engines, heat exchangers, vials, syringes, ampoules, medical wires, secondary batteries such as lithium ion batteries, primary batteries such as lithium batteries, radical batteries, solar cells, fuel cells, lithium ion capacitors, hybrid capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive and negative electrodes).
• the dispersion to which this method is applied is also useful as an adhesive for bonding parts.
• the dispersion to which this method is applied can be used for bonding ceramic parts, bonding metal parts, bonding electronic parts such as IC chips, resistors, and capacitors on substrates of semiconductor elements and module parts, bonding circuit boards and heat sinks, and bonding LED chips to substrates.
• Molded articles such as sheets and laminates formed from the present dispersion using this method are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, heat dissipation parts, etc.
• these include electric wire coating materials (aircraft electric wires, etc.), enameled wire coating materials used in motors for electric vehicles, etc., electrical insulating tape, insulating tape for oil drilling, oil transport hoses, hydrogen tanks, materials for printed circuit boards, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, for fuel cells, etc.), copy rolls, furniture, automobile dashboards, covers for home appliances, etc., sliding parts (load bearings, yaw bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings, etc.), and other applications.
• electric wire coating materials aircraft electric wires, etc.
• tension ropes tension ropes, wear pads, wear strips, tube lamps, test sockets, wafer guides, wear parts of centrifugal pumps, chemical and water supply pumps, tools (shovels, files, hacksaws, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, dies, toilets, container coating materials, heat dissipation boards mounted for power devices, heat dissipation members for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOS FETs, CPUs, heat dissipation fins, metal heat sinks, blades for windmills, wind power generation equipment, aircraft, etc., housings for personal computers and displays, electronic device materials, interior and exterior parts of automobiles, processing machines and vacuum ovens that perform heat treatment under low oxygen conditions, sealing materials for plasma treatment devices, heat dissipation parts in treatment units for sputtering and various dry etching devices, and electromagnetic wave shields.
• Sheets and other molded articles and laminates formed from this dispersion using this method are useful as electronic substrate materials such as flexible printed wiring boards and rigid printed wiring boards, as protective films and heat dissipation substrates, particularly heat dissipation substrates for automobiles.
• the dispersions produced by this method can also be used as coatings for coating feedthroughs through battery or capacitor housings made of light metals such as aluminum, magnesium, titanium, silicon carbide, and alloys thereof with F polymer.
• feedthroughs include those in which the housing has an opening with a conductor passing through a glass material that seals the opening.
• the glass material may be a glass ceramic material, and specific examples thereof include the materials described in JP-A-2018-502417.
• the conductor may be a material suitable for an electrode material of a battery or a capacitor, for example, copper or a copper alloy for a cathode of a battery.
• the conductor may be made of different materials on the inside and outside of the housing.
• the present invention also provides a dispersion container in which the present dispersion is contained, the liquid density of the present dispersion is in the range of 95.0% or more and less than 99.9% of the theoretical liquid density of the present dispersion calculated by the above formula (1), and the product of the gas phase volume ratio in the container and the gas-liquid interface area of the container is in the range of 10000 or more and 60000 or less.
• the components of the dispersion liquid namely, the F polymer, the F particles, the nonionic surfactant, the content ratio of the F particles, the nonionic surfactant, and the water, the inorganic filler, the aromatic polymer, and the various additives that may be contained as necessary, and the storage container in such a dispersion liquid storage body are the same as those described above in the explanation of the present method.
• the present invention is not limited to the configurations of the above-mentioned embodiments.
• the present method and the dispersion liquid container may be configured in the above-mentioned embodiments with the addition of any other configuration, or may be replaced with any configuration that exhibits a similar function.
• F Particle 1 Particles of a tetrafluoroethylene polymer (melting temperature: 300° C.) containing 97.9 mol %, 0.1 mol %, and 2.0 mol % of TFE units, NAH units, and PPVE units, in that order, and having 1,000 carbonyl group-containing groups per 1 ⁇ 10 6 main chain carbon atoms (D50: 2.0 ⁇ m, density: 2.13 g/cm 3 ).
• F particles 2 Particles made of a tetrafluoroethylene-based polymer (melting temperature: 300° C.) containing 97.5 mol % TFE units and 2.5 mol % PPVE units, in that order, and having no oxygen-containing polar group (D50: 2.0 ⁇ m, density: 2.13 g/cm 3 ).
• Dispersion 1 95 parts by mass of F particles 1, 5 parts by mass of surfactant 1, and 100 parts by mass of water were placed in a container and stirred at 1000 rpm with a homodisper to obtain dispersion liquid 1.
• ⁇ Dispersion 2 95 parts by mass of F particles 2, 5 parts by mass of surfactant 1, and 100 parts by mass of water were placed in a container and stirred at 1000 rpm with a homodisper to obtain dispersion liquid 2.
• ⁇ Dispersion 3 95 parts by mass of F particles 1, 5 parts by mass of surfactant 2, and 100 parts by mass of water were placed in a container and stirred at 1000 rpm with a homodisper to obtain dispersion liquid 3.
• Dispersion 1 was allowed to stand while being stirred at 100 rpm with a homodisper to defoam it, and stirring was stopped when the liquid density reached 1.336 g/cm 3.
• the theoretical liquid density of the dispersion was 1.338 g/cm 3 , and the liquid density/theoretical liquid density was 99.8%.
• the gas-liquid interface area in container A was equal to the bottom area of container A
• the product of the gas phase volume ratio in container A and the gas-liquid interface area of the storage container was 14130.
• Example 2 to [Example 7] Each dispersion was stored in the same manner as in Example 1, except that the type of dispersion used for storage, the liquid density adjusted during storage, the type of storage container, and the storage temperature were changed as shown in Table 1.
• Dispersion 3-1 Average Amount of Dissolved Oxygen The average amount of dissolved oxygen in each dispersion stored in each example was measured in ppm using an optical dissolved oxygen meter "DOP-01" (Automatic Systems Research Co., Ltd.) Measurements were taken every 24 hours, and the average value over a storage period of 6 months was calculated.
• DOP-01 optical dissolved oxygen meter
• each dispersion was applied to the surface of polyimide using a bar coater, forming a liquid coating.
• the polyimide film on which the liquid coating was formed was then passed through a drying oven at 120°C for minutes and dried by heating to obtain a dry coating.
• the dry coating was then heated at 350°C for 5 minutes in a nitrogen oven to produce a laminate having a polymer layer (thickness 25 ⁇ m) containing a molten and baked product of F particles on the surface of the polyimide film.
• the polymer layer was separated from the obtained laminate, and the yellow index (YI) was measured using a color meter SM-T (manufactured by Suga Test Instruments Co., Ltd.) and evaluated according to the following criteria.
• YI yellow index
• Dispersion liquid container 2 was prepared by changing agent 1 in dispersion liquid 1 of the dispersion liquid container of Example 1 (dispersion liquid container 1) to agent 2, and dispersion liquid container 3 was prepared by changing agent 1 in dispersion liquid container 1 to agent 3, and dispersion liquid containers 1 to 3 were stored for four months.
• a constant-volume liquid delivery pump was attached to each dispersion liquid container after long-term storage, and a transfer test to another container was carried out.
• dispersion liquid container 1 was capable of the most uniform and constant transfer
• dispersion liquid container 2 tended to cause clogging in the transfer line
• dispersion liquid container 3 tended to cause the composition of the dispersion liquid to be unstable at the beginning of the transfer.
• This method suppresses the deterioration of the F polymer and the discoloration of the dispersion even after the aqueous dispersion containing the F polymer is stored for a long period of time. From the dispersion to which this method is applied, it is possible to form a molded product such as a coating film that highly expresses the physical properties of the F polymer, has little discoloration, and is excellent in adhesion and surface appearance, specifically a laminate having a polymer layer formed from the dispersion.

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• 2023
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