Manufacturing method for long laminated substrates

Abstract

To provide a method for manufacturing a long laminated base material, which can continuously form a polymer layer containing a tetrafluoroethylene polymer and exhibits excellent heat resistance and physical property such as electric characteristics, particularly excellent surface appearance, with high productivity.SOLUTION: The method for manufacturing the long laminated base material having a coating layer for forming a base material layer and a polymer layer on the surface of the base material layer through melting and burning coats the surface of the long base material by applying a dispersion liquid containing particles of a tetrafluoroethylene-based polymer and a liquid dispersion medium in a reverse coater method. The viscosity of the liquid dispersion is 100-5000 mPa s, the content of the particles of the tetrafluoroethylene-based polymer in the liquid dispersion is 15-45 mass%, and the gap width and the surface hardness of a roll are specified as a condition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a long laminated base material having a polymer layer containing a tetrafluoroethylene-based polymer.

Background Art

[0002] In recent years, in order to cope with the high speed and high frequency of mobile communication devices such as mobile phones, materials with a low dielectric constant and a low dielectric tangent are required for the insulating layer of the printed circuit board of the communication device, and tetrafluoroethylene-based polymers have attracted attention. As a material for forming an insulating layer containing such a polymer, a dispersion liquid containing particles of a tetrafluoroethylene-based polymer and a liquid dispersion medium is known. As a method of applying such a dispersion liquid to a base material, Patent Document 1 proposes a reverse roll coater method in which two coater rolls are arranged as backup rolls of each coater head, and a double-sided simultaneous coating device for an aqueous dispersion liquid of a tetrafluoroethylene-based polymer. Patent Document 2 proposes a method for forming an adhesive film on a fluororesin sheet, in which a solution-based adhesive obtained by mixing polyvinylidene fluoride and polymethyl methacrylate is applied to a base material that is a resin film by a reverse coating method, and the adhesive surface of the adhesive-coated base material is bonded to a fluororesin sheet and then the resin base material is peeled off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When forming the polymer layer that serves as the insulating layer from a dispersion containing tetrafluoroethylene polymer particles and a liquid dispersion medium with high productivity, it is required that the polymer layer surface be free of defects and streaks, maintain uniformity of thickness, and increase density, in order to fully exhibit its properties. On the other hand, roll coater type coating equipment is widely used for continuous coating of long substrates in motion. Such equipment includes a natural coater system in which the rotation direction of the coating roll is the same as the direction of travel of the long substrate, and a reverse coater system in which the rotation direction of the coating roll is opposite to the direction of travel of the long substrate. The reverse coater system is suitable for eliminating roll marks on the coated surface and obtaining a smooth coating film, but if the viscosity of the coating liquid is relatively high and contains air bubbles, etc., the bubbles may burst during high-speed coating, resulting in uneven coating. Because tetrafluoroethylene polymers have low surface tension, their particles have poor dispersibility, and the dispersion tends to foam easily. As a result, the handling properties, such as fluidity, in applications like coating are not entirely satisfactory. Due to these characteristics of the dispersion, there is still room for improvement in the coating methods proposed in Patent Documents 1 and 2 from the viewpoint of continuously and productively forming polymer layers. The inventors have discovered that by applying a specific reverse coater method, specifying the surface hardness of the roll and the operating conditions, and using a dispersion with viscosity and tetrafluoroethylene polymer particle content within a specific range, the formation of coarse particles is suppressed, and laminates having a polymer layer with excellent surface appearance can be continuously and productively formed. Furthermore, they have found that the resulting polymer layer has excellent physical properties such as heat resistance and electrical properties (low coefficient of thermal expansion, low dielectric constant, and low dielectric loss tangent) based on the tetrafluoroethylene polymer, leading to the present invention. The object of the present invention is to provide a method for manufacturing a long laminated substrate that can continuously and productively form a polymer layer containing a tetrafluoroethylene-based polymer, which has excellent physical properties such as heat resistance and electrical properties, and in particular excellent surface appearance. [Means for solving the problem]

[0005] The present invention has the following aspects. [1] A method for manufacturing a long laminated substrate having a substrate layer and a coating layer for forming a polymer layer on the surface of the substrate layer by melt firing, wherein the viscosity of the dispersion is 100 to 5000 mPa·s, the content of the tetrafluoroethylene polymer particles in the dispersion is 15 to 45% by mass, the width of the gap is greater than the product of the thickness of the polymer layer and the reciprocal of the content ratio of the tetrafluoroethylene polymer particles in the dispersion, and the surface hardness of at least one of the coating roll, the metering roll and the backup roll is 60 to 75 degrees. [2] The method for manufacturing [1], wherein the surface hardness of the coating roll, the metering roll, and the backup roll are all 60 to 75 degrees. [3] A method for producing [1] or [2], wherein the tetrafluoroethylene polymer particles are heat-meltable tetrafluoroethylene polymer particles having an average particle diameter of 0.3 μm or more and less than 10 μm. [4] A method for producing any of [1] to [3], wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group. [5] A method of production according to any one of [1] to [4], wherein the liquid dispersion medium is at least one selected from the group consisting of water, amides, ketones, and esters. [6] A method of production according to any one of [1] to [5], wherein the dispersion further contains at least one nonionic surfactant selected from the group consisting of alcohol-based surfactants and silicone-based surfactants. [7] A method for producing the dispersion according to any one of the methods described in [1] to [6], wherein the dispersion further contains at least one thickener selected from the group consisting of acrylic acid polymers, vinyl alcohol polymers, and cellulose polymers. [8] A method of production according to any one of [1] to [7], wherein the dispersion further contains an alcohol having 1 to 6 carbon atoms. [9] A method of manufacturing the dispersion, wherein the surface tension of the dispersion is 20 to 30 mN / m, according to any of the methods of [1] to [8].

[10] A method for manufacturing the long laminated substrate having the polymer layer on both surfaces of the long substrate, as described in any of [1] to [9].

[11] A method of manufacturing any of [1] to

[10] , wherein the long substrate is a heat-resistant substrate.

[12] A method for producing

[11] , wherein the heat-resistant substrate is a polyimide film.

[13] A method of production according to any one of [1] to

[12] , wherein the width of the gap is greater than 1 and less than or equal to 1.2 times the product of the thickness of the polymer layer and the content ratio of the tetrafluoroethylene polymer particles in the dispersion.

[14] The method for producing

[13] , wherein the thickness of the polymer layer is 20 μm or more. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a method for manufacturing a long laminated substrate that can continuously and productively form a polymer layer containing a tetrafluoroethylene-based polymer, which has excellent physical properties such as heat resistance and electrical properties, and in particular excellent surface appearance. [Modes for carrying out the invention]

[0007] The following terms have the following meanings: The "average particle diameter (D50)" is the 50% cumulative diameter of a particle based on its volume, determined by laser diffraction and scattering. Specifically, the particle size distribution is measured using laser diffraction and scattering, and a cumulative curve is determined with the total volume of the particle collection set to 100%. The D50 is the particle diameter at the point on that cumulative curve where the cumulative volume reaches 50%. The D50 of a particle is determined by dispersing the particle in water and analyzing it using the laser diffraction / scattering method with a laser diffraction / scattering particle size distribution analyzer (LA-920 analyzer, manufactured by Horiba, Ltd.). The "average particle diameter (D90)" is the 90% cumulative diameter based on the volume of the particle, and is determined in the same way as D50. The specific surface area of ​​a particle is a value calculated by measuring the particle using the gas adsorption (constant volume method) BET multipoint method, and is determined using the NOVA4200e (manufactured by Quantachrome Instruments). The "melting temperature" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by differential scanning calorimetry (DSC). The "glass transition temperature (Tg)" is a value measured by analyzing a polymer using the dynamic viscoelasticity measurement (DMA) method. Viscosity is determined by measuring the viscosity of a dispersion using a B-type viscometer at 25°C and a rotation speed of 30 rpm. The measurement is repeated three times, and the average of the three measurements is used. The "thixotropic ratio" is calculated by dividing the viscosity η1 of the dispersion, measured at a rotation speed of 30 rpm, by the viscosity η2, measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average of the three measurements is used. The "surface tension" of a solvent or solution is the value measured using a surface tensimeter at 25°C by the Wilhelmy method. The HLB (Hydrophilic-Lipophilic Balance) value of nonionic surfactants is defined by the following formula, calculated using the Griffin method. HLB value = 20 × [sum of chemical formula weights of hydrophilic parts] / molecular weight The "degree of substitution" of cellulose ether, also known as the degree of etherification, represents the average number of hydroxyl groups substituted with alkoxyl groups among the three hydroxyl groups on the glucose ring of cellulose. Theoretically, the degree of substitution can be between 0 and 3, and generally, the higher the substituent, the more hydrophilic the molecule becomes. The degree of substitution is determined by converting the value measured by the degree of substitution analysis method for hydroxypropyl methylcellulose described in the 18th edition of the Japanese Pharmacopoeia. In polymers, a "unit" refers to an atomic group based on a monomer, formed by the polymerization of the monomer. A unit may be directly formed by the polymerization reaction, or it may be a unit in which a portion of the unit is converted to a different structure by processing the polymer. Hereinafter, a unit based on monomer a will also be simply referred to as a "monomer a unit."

[0008] The manufacturing method of the present invention (hereinafter also referred to as "this method") involves supplying a dispersion (hereinafter also referred to as "this dispersion") containing particles of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") (hereinafter also referred to as "F particles") and a liquid dispersion medium to a liquid reservoir provided on the rear side of the coating roll, a metering roll positioned above the coating roll and equipped with a doctor knife on the rear side of the coating roll, the dispersion being passed through the gap between the coating roll and the metering roll, and a rotating bar positioned in front of the coating roll. A method for manufacturing a long laminated substrate having a substrate layer and a coating layer for forming a polymer layer on the surface of the substrate layer by melt firing, wherein the viscosity of the dispersion is 100 to 5000 mPa·s and the content of the tetrafluoroethylene polymer particles in the dispersion is 15 to 45% by mass, the width of the gap is greater than the product of the thickness of the polymer layer and the reciprocal of the content ratio of the tetrafluoroethylene polymer particles in the dispersion, and the surface hardness of at least one of the coating roll, the metering roll and the backup roll is 60 to 75 degrees.

[0009] The long laminated substrates obtained by this method have excellent physical properties such as heat resistance and electrical properties (low coefficient of thermal expansion, low dielectric constant, and low dielectric loss tangent) based on the F polymer in the polymer layer formed from the coating layer, and are particularly excellent in surface appearance. In this specification, "excellent surface appearance" includes both excellent surface smoothness, such as "little surface roughness," and excellent appearance as observed by visual inspection or analytical instruments, such as "no streaks, cracks, or defects on the surface." Although the reason why a long laminated base material with an excellent polymer layer surface appearance can be obtained by this method is not necessarily clear, it can be considered as follows.

[0010] In this method, a specific reverse coater method is applied, the gap width between the coating roll and the metering roll is defined in relation to the F particle content ratio of this dispersion liquid, the viscosity of this dispersion liquid is further set within a specific range, and at least one surface hardness of the coating roll, the metering roll and the backup roll is set within the above-mentioned range. That is, in this method, by passing this dispersion liquid with a specific viscosity range and a specific F particle content through the gap, the adhesion of the dispersion liquid to the roll and the entrainment of air are suppressed, and the foaming caused thereby is suppressed. And the external pressure applied to this dispersion liquid from any roll is adjusted and buffered by the hardness of the roll surface, and the foaming is synergistically suppressed. In particular, when the pressure applied to this dispersion liquid when it is transferred from the coating roll to the long base material on the backup roll is buffered by the backup roll with a specific surface hardness, this effect becomes remarkable. Thereby, especially when the line speed of the long base material and the peripheral speed of each roll are increased to increase the production speed, the occurrence of layer defects such as coating layer displacement and streaks due to the spread of this dispersion liquid after passing through the gap can be effectively suppressed. Such an effect becomes more remarkable when this dispersion liquid contains a specific nonionic surfactant, a specific thickener, and an alcohol having 1 to 6 carbon atoms as described later, when the F polymer has an oxygen-containing polar group, and when the surface tension of this dispersion liquid is within a specific range.

[0011] In this method, the F polymer constituting this dispersion liquid is a polymer containing a unit based on tetrafluoroethylene (hereinafter also referred to as "TFE") (hereinafter also referred to as "TFE unit"). The F polymer may be thermally fusible or non-thermally fusible, but is preferably thermally fusible. Here, the thermally fusible polymer means a polymer having a temperature at which the melt flow rate is 1 to 1000 g / 10 minutes under the condition of a load of 49 N. The melting temperature of the heat-meltable F polymer is preferably 180°C or higher, and more preferably 200°C or higher. The melting temperature of the F polymer is preferably 325°C or lower, and more preferably 320°C or lower. In this case, the coating film (polymer layer) formed from this dispersion tends to have excellent heat resistance.

[0012] The glass transition temperature of the F polymer is preferably 50°C or higher, and more preferably 75°C or higher. The glass transition temperature of the F polymer is preferably 150°C or lower, and more preferably 125°C or lower. The fluorine content of the F polymer is preferably 70% by mass or more, and more preferably 72-76% 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 the wettability test mixture (manufactured by Wako Pure Chemical Industries, Ltd.) specified in JIS K 6768 onto a flat plate made of the F polymer.

[0013] The F polymer is preferably polytetrafluoroethylene (PTFE), a polymer containing TFE units and ethylene-based units (ETFE), a polymer containing TFE units and propylene-based units, a polymer containing TFE units and perfluoro(alkyl vinyl ether) (PAVE)-based units (PAVE units) (PFA), or a polymer containing TFE units and hexafluoropropylene-based units (FEP), with PFA and FEP being more preferred, and PFA being even more preferred. These polymers may further contain units based on other comonomers. Examples of PTFE include low molecular weight PTFE and modified PTFE. PAVE is preferably CF2=CFOCF3, CF2=CFOCF2CF3, and CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"), with PPVE being more preferred.

[0014] The F polymer preferably has an oxygen-containing polar group, more preferably a hydroxyl group-containing group or a carbonyl group-containing group, and even more preferably a carbonyl group-containing group. In this case, the dispersion is likely to exhibit excellent dispersion stability and ease of handling. Furthermore, the polymer layer formed from this dispersion is likely to exhibit excellent physical properties such as heat resistance, electrical properties (low coefficient of thermal expansion, low dielectric constant, and low dielectric loss tangent), and surface appearance. The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, and -CF2CH2OH and -C(CF3)2OH are more preferred. The carbonyl group-containing groups are preferably carboxyl groups, alkoxycarbonyl groups, amide groups, isocyanate groups, carbamate groups (-OC(O)NH2), acid anhydride residues (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.), and carbonate groups (-OC(O)O-), with acid anhydride residues being more preferred. If the F polymer has oxygen-containing polar groups, the number of oxygen-containing polar groups in the F polymer is 1 × 10⁶ carbon atoms in the main chain. 6 The number of oxygen-containing polar groups per polymer is preferably 10 to 5000, and more preferably 100 to 3000. The number of oxygen-containing polar groups in polymer F can be quantified by the polymer composition or by the method described in International Publication No. 2020 / 145133.

[0015] The oxygen-containing polar group may be included in the monomer-based units in the F polymer, or it may be included in the terminal groups of the main chain of the F polymer, with the former being preferred. Examples of the latter include an F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and an F polymer obtained by plasma treatment or ionization treatment of the F polymer.

[0016] The F polymer is preferably a polymer having carbonyl group-containing groups, including TFE units and PAVE units. More preferably, it is a polymer containing TFE units, PAVE units, and units based on monomers having carbonyl group-containing groups, with these units present in the following proportions relative to the total number of units: 90-99 mol%, 0.99-9.97 mol%, and 0.01-3 mol%. A specific example of such an F polymer is the polymer described in International Publication No. 2018 / 16644. The monomers having a carbonyl group are preferably itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), with NAH being more preferred.

[0017] The D50 of the F particles is preferably 0.3 μm or more and less than 10 μm. The F particles may be solid particles or non-hollow particles. The F particles may be secondary particles formed from nanoparticles on the order of nm. The D50 of the F particles is preferably 1 μm or more, more preferably 1.5 μm or more. The D50 of the F particles is preferably 6 μm or less, more preferably 5 μm or less.

[0018] The specific surface area of ​​F particles is 1 to 25 m². 2 It is preferable that the amount is / g, and 6-15m 2 / g is preferable. In this case, the dispersion is likely to exhibit excellent dispersion stability and ease of handling. Furthermore, the polymer layer obtained by melting and firing the coating layer formed from this dispersion is likely to exhibit excellent physical properties such as heat resistance, electrical properties (low coefficient of thermal expansion, low dielectric constant, and low dielectric loss tangent), and surface appearance. When the specific surface area of ​​the F particles is within the above range, the surface of the F particles is easily wettable with the liquid dispersion medium or with the monool with 1 to 6 carbon atoms described later, making it easier for aggregates of F particles to break down, and thus the above-mentioned mechanism of action is more likely to manifest.

[0019] F particles are particles containing F polymer, and it is preferable that they consist of F polymer. It is more preferable that the F particles are particles of a heat-meltable F polymer having oxygen-containing polar groups and a melting temperature of 200 to 325°C. In this case, the above-described mechanism of action is more readily expressed, and aggregation of the F particles is more easily suppressed.

[0020] One type of F particle may be used, or two or more types may be used. Furthermore, the F particles may be used in combination with particles of a non-thermally soluble tetrafluoroethylene polymer. Preferably, the F particles are particles of a heat-soluble F polymer with a melting temperature of 200 to 325°C, more preferably heat-soluble F polymer particles with a melting temperature of 200 to 325°C and containing oxygen-containing polar groups, and preferably non-thermally soluble PTFE particles as the non-thermally soluble tetrafluoroethylene polymer particles. In this case, the aggregation-inhibiting effect of the heat-soluble F polymer particles and the retention effect due to fibrillation of the non-thermally soluble tetrafluoroethylene polymer are balanced, which tends to improve the dispersibility of the dispersion. In addition, the electrical properties of the non-thermally soluble tetrafluoroethylene polymer tend to be highly expressed in the polymer layer formed therefrom.

[0021] In this method, the liquid dispersion medium constituting the dispersion is preferably at least one selected from the group consisting of water, amides, ketones, and esters. Examples of amides 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. Examples of ketones include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, and cycloheptanone. Examples of esters include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl 3-ethoxypropionate, γ-butyrolactone, and γ-valerolactone. These can be used individually or in combination of two or more types. Furthermore, the liquid dispersion medium is preferably miscible with a water-soluble solvent and water having a surface tension within a specific range, as described later, and it is more preferable that the liquid dispersion medium is water.

[0022] This dispersion may further contain a nonionic surfactant. Examples of nonionic surfactants include glycol-based surfactants, alcohol-based surfactants, silicone-based surfactants, or fluorine-based surfactants. In particular, it is preferable to contain at least one nonionic surfactant selected from the group consisting of alcohol-based surfactants and silicone-based surfactants.

[0023] The alcohol-based surfactant used as a nonionic surfactant preferably has an HLB value of less than 10, and more preferably less than 4. The alcohol-based surfactant is preferably an acetylenediol-based surfactant. An acetylenediol-based surfactant is a surfactant that has a carbon-carbon triple bond in its molecule. Examples of acetylenediol-based surfactants include acetylenediol surfactants (which have an acetylene bond and two hydroxyl groups within the same molecule) and surfactants obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to acetylenediol. Specific examples of such acetylenediol-based surfactants include the "Surfinol®" series and the "Orfin®" series (both manufactured by Nisshin Chemical Industry Co., Ltd.); and the "Acetylenel®" series (manufactured by Kawaken Fine Chemical Co., Ltd.).

[0024] The silicone-based surfactant used as a nonionic surfactant is preferably one with an HLB value of 10 or higher, and more preferably a polyoxyalkylene-modified dimethylsiloxane having a polyoxyalkylene structure as the hydrophilic portion and a polydimethylsiloxane structure as the hydrophobic portion. Polyoxyalkylene-modified dimethylsiloxane has a main chain of polydimethylsiloxane units (-(CH3)2SiO 2 / 2It may have a -), may have polydimethylsiloxane units in the side chain, or may have polydimethylsiloxane units in both the main chain and the side chain. The polyoxyalkylene-modified polydimethylsiloxane is preferably a polyoxyalkylene-modified polydimethylsiloxane having dimethylsiloxane units in the main chain and oxyalkylene groups in the side chain, or a polyoxyalkylene-modified polydimethylsiloxane having dimethylsiloxane units in the main chain and oxyalkylene groups at the ends of the main chain. Furthermore, the oxyalkylene groups contained in polyoxyalkylene-modified dimethylsiloxane may consist of only one type of oxyalkylene group, or they may consist of two or more types of oxyalkylene groups. In the latter case, the different types of oxyalkylene groups may be linked together randomly or in a block-like manner.

[0025] Examples of such silicone-based surfactants include "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", and "BYK-3456" (manufactured by Bic Chemie Japan Co., Ltd.), and "KF-6011" and "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0026] If the dispersion further contains a nonionic surfactant, its content is preferably in the range of 1 to 15% by mass, and more preferably in the range of 3 to 10% by mass, relative to the F particles in the dispersion. Nonionic surfactants may be used individually or in combination of two or more. In particular, it is preferable that the dispersion contains both alcohol-based surfactants and silicone-based surfactants as nonionic surfactants, as this makes the above-described mechanism of action more readily apparent. When this dispersion contains both alcohol-based and silicone-based surfactants as nonionic surfactants, the mass ratio of alcohol-based surfactants to silicone-based surfactants is not particularly limited and can be appropriately set within the range of, for example, 5:95 to 95:5.

[0027] In this method, the dispersion may further contain a thickening agent. When a thickening agent is included, the dispersion state and dispersion stability of the dispersion tend to improve. In addition, the rheological properties improve, making it easier to handle the dispersion, such as its film-forming properties, and thus easier to form a thicker polymer layer using this method. The thickening agent is preferably at least one thickening agent selected from the group consisting of acrylic acid polymers, vinyl alcohol polymers, and cellulose polymers.

[0028] Examples of vinyl alcohol-based polymers include polyvinyl alcohol, polyvinyl acetate, partially acetylated or partially acetalized polyvinyl alcohol, and copolymers of vinyl alcohol, vinyl butyral, and vinyl acetate. Specific examples of vinyl alcohol-based polymers include the "Eslec® B" series, the "Eslec® K (KS)" series, the "Eslec® SV" series (all manufactured by Sekisui Chemical Co., Ltd.), and the "Mobital®" series (manufactured by Kuraray Co., Ltd.). Examples of acrylic acid-based polymers include polyacrylic acid, sodium polyacrylate, sodium acrylic acid / maleic acid copolymer, sodium acrylic acid / sulfonic acid monomer copolymer, and other salts of polyacrylic acid; polyacrylates such as methyl polyacrylate and ethyl polyacrylate; poly-α-haloacrylate; poly-α-cyanoacrylate; and polyacrylamide.

[0029] Examples of cellulose-based polymers include cellulose ethers such as alkylcellulose, carboxyalkylcellulose, hydroxyalkylcellulose, and hydroxyalkylalkylcellulose. Examples of alkylcellulose include methylcellulose and ethylcellulose. Examples of carboxyalkylcellulose include carboxymethylcellulose. Examples of hydroxyalkylcellulose include hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose. Examples of hydroxyalkylalkylcellulose include hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxyethyl ethylcellulose, and hydroxyethyl ethyl methylcellulose. Among these, hydroxyalkylcellulose or hydroxyalkylalkylcellulose is preferred, hydroxyalkylcellulose is more preferred, and hydroxyethylcellulose is even more preferred.

[0030] If a thickening agent is included, its content is preferably 0.1% by mass or more, and more preferably 0.2% by mass or more, relative to the total mass of the dispersion. The content of the thickening agent is preferably 30% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the dispersion. Furthermore, the ratio of the thickening agent content to the F particle content in this dispersion is preferably 0.001 or higher, more preferably 0.003 or higher. This ratio is preferably 0.05 or lower, more preferably 0.03 or lower, and even more preferably 0.01 or lower.

[0031] This dispersion may further contain a monool having 1 to 6 carbon atoms. Such a monool having 1 to 6 carbon atoms is a compound that is liquid at 25°C under atmospheric pressure, preferably with a boiling point of 160°C or lower, and more preferably with a boiling point of 120°C or lower. Furthermore, a water-soluble compound with a surface tension of 20 to 30 mN / m is preferred, and azeotropic formation with water is preferred. In this specification, "water-soluble" means having a solubility in water of 100 g / L or more. Among the carbon-1 to carbon-6 monools, methanol (23 mN / m), ethanol (23 mN / m), 1-propanol (24 mN / m), 2-propanol (22 mN / m), 1-butanol (25 mN / m), 2-butanol (24 mN / m), isobutanol (23 mN / m), 1-methoxy-2-propanol (26 mN / m), 2-propoxyethanol (27 mN / m), 1-propoxy-2-propanol (25 mN / m), and 2-ethoxyethanol (26 mN / m) are more preferred, and ethanol is even more preferred. The numbers in parentheses represent the surface tension of each monool. These may be used individually or in combination of two or more types. When using two or more of the aforementioned monools, it is preferable that they are mutually compatible.

[0032] This dispersion may further contain inorganic particles. In this case, the polymer layer formed from this dispersion tends to exhibit excellent electrical properties and low linear expansion. The shape of the inorganic particles may be spherical, needle-shaped (fibrous), or plate-shaped. Specifically, they may be spherical, flaky, layered, leaf-shaped, almond-shaped, columnar, cockscomb-shaped, equiaxed, leaf-shaped, mica-like, block-shaped, plate-shaped, wedge-shaped, rosette-shaped, reticulated, or prismatic. Examples of inorganic particles 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 particle may be used, or two or more types may be used in combination. The D50 of the inorganic particles is preferably 0.1 to 50 μm. The surface of the inorganic particles may be surface-treated with a silane coupling agent.

[0033] Suitable examples of inorganic particles include silica particles (such as the "AdmaFine®" series (manufactured by Admatex Co., Ltd.), the "SFP®" series (manufactured by Denka Co., Ltd.), the "E-SPHERES" series (manufactured by Taiheiyo Cement Corporation), etc.), zinc oxide particles (such as the "FINEX®" series (manufactured by Sakai Chemical Industry Co., Ltd.), titanium oxide particles (such as the "Typake®" series (manufactured by Ishihara Sangyo Co., Ltd.), the "JMT®" series (manufactured by Teika Co., Ltd.), etc.), talc particles (such as the "SG" series (manufactured by Nippon Talc Co., Ltd.), steatite particles (such as the "BST" series (manufactured by Nippon Talc Co., Ltd.)), and boron nitride particles (such as the "HP40MF" series, the "HP40J" series (both manufactured by Mizushima Iron Alloy Co., Ltd.), the "UHP" series (manufactured by Showa Denko Corporation), and the "GP" and "HGP" grades of the "Denka Boron Nitride" series (manufactured by Denka Co., Ltd.)). If the dispersion contains inorganic particles, the inorganic particle content in the dispersion is preferably 1 to 25% by mass.

[0034] The dispersion may further contain other resins different from the F polymer. Such other resins may be included in the dispersion as non-hollow particles, or they may be dissolved or dispersed in the liquid dispersion medium constituting the dispersion, and optionally in the contained carbon-1 to carbon-6 monools. Other resins include polyester resins such as liquid crystalline aromatic polyesters, polyimide resins, polyamide-imide resins, epoxy resins, maleimide resins, urethane resins, polyphenylene ether resins, polyphenylene oxide resins, and polyphenylene sulfide resins. As for other resins, aromatic polymers are preferred, and at least one 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 included in the dispersion as a varnish dissolved in the liquid dispersion medium.

[0035] Specific examples of aromatic imide polymers include the "Yupia-AT" series (manufactured by Ube Industries), the "Neoprim®" series (manufactured by Mitsubishi Gas Chemical Company), the "Spixeria®" series (manufactured by Somar), the "Q-PILON®" series (manufactured by PI Technical Research Institute), the "WINGO" series (manufactured by Wingo Technology), the "Tomide®" series (manufactured by T&K TOKA), the "KPI-MX" series (manufactured by Kawamura Industries), and "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials). If the dispersion further contains other resins, the content of the other resins relative to the F particles is preferably 1 to 25% by mass.

[0036] This dispersion may further contain additives such as thixotropic agents, defoaming agents, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, and flame retardants.

[0037] This dispersion is obtained by mixing F particles, a liquid dispersion medium, and, if necessary, the aforementioned nonionic surfactant, thickener, monool with 1 to 6 carbon atoms, inorganic particles, other resins, additives, etc. When nonionic surfactants, thickeners, monools with 1 to 6 carbon atoms, inorganic particles, other resins, additives, etc. are to be further mixed as needed, they may be mixed all at once when mixing the F particles with the liquid dispersion medium, or they may be added sequentially to the mixture of F particles and the liquid dispersion medium and mixed. There are no particular restrictions on the order of mixing, and the mixing method may be all at once or in multiple stages. When adding a nonionic surfactant to this dispersion, it may be added as is or as an aqueous solution. Furthermore, when using both the alcohol-based surfactant and the silicone-based surfactant as the nonionic surfactant, there are no particular restrictions on the order of addition, and they may be added as an aqueous solution in which both are dissolved. When cellulose ether is added to this dispersion as a thickening agent, it may be added as a powder or an aqueous solution thereof, or it may be added in a state where it is dispersed or dissolved in a liquid defoamer or the like.

[0038] Mixing apparatus for obtaining this dispersion includes stirring devices equipped with blades such as Henschel mixers, pressurized kneaders, Banbury mixers, and planetary mixers; grinding devices equipped with media such as ball mills, attritors, basket mills, sand mills, sand grinders, Dino mills, disper mats, SC mills, spike mills, and agitator mills; and dispersion apparatus equipped with other mechanisms such as microfluidizers, nanomizers, ultimateizers, ultrasonic homogenizers, desolvers, dispersers, high-speed impellers, thin-film swirling high-speed mixers, rotating and revolving agitators, and V-type mixers.

[0039] Mixing of F particles and liquid dispersion medium is preferably carried out using a planetary mixer or a rotating-orbiting agitator. A planetary mixer is an agitator having two agitation blades that rotate and revolve relative to each other. The resulting mixture may be a dispersed liquid, a paste (such as a paste with a viscosity of 1,000 to 100,000 mPa·s), or a wet powder (such as a wet powder with a viscosity of 10,000 to 100,000 Pa·s as measured by a capillograph). The viscosity measured by the capillary graph is calculated using a capillary with a length of 10 mm and a radius of 1 mm, with a furnace diameter of 9.55 mm, a load cell capacity of 2 t, a temperature of 25°C, and a shear rate of 1 s. -1 This is the value measured as such.

[0040] The content of F particles in this dispersion is preferably 15 to 45% by mass, and more preferably 25 to 40% by mass. The content of the liquid dispersion medium in this dispersion is preferably 50% by mass or more, and more preferably 55% by mass or more. The content of the liquid dispersion medium is preferably less than 85% by mass, and more preferably 60% by mass or less. Furthermore, the content of the liquid dispersion medium in this dispersion is preferably 100 to 200% by mass relative to the content of F particles. Furthermore, if this dispersion contains a monool with 1 to 6 carbon atoms, it is also possible that, from the perspective of dispersion stability of F particles, such monools with 1 to 6 carbon atoms play a role as defoamers, such as anti-foaming or anti-foaming effects, even if they contain a large amount of nonionic surfactant.

[0041] In this method, the viscosity of the dispersion is 100 to 5000 mPa·s, with 500 to 3000 mPa being more preferable. In this case, the dispersion exhibits excellent coating properties and readily forms a polymer layer with a superior surface appearance in this method. Furthermore, in a dispersion within this viscosity range, the physical properties of the F polymer are highly readily expressed in the polymer layer formed therefrom. The thixotropy ratio of this dispersion is preferably 1.0 to 3.0. In this case, the dispersion exhibits excellent coating properties and homogeneity, and is more likely to produce a denser polymer layer. These liquid properties tend to improve when the dispersion contains the nonionic surfactant and thickener described above.

[0042] In this method, the surface tension of the dispersion is preferably 20 to 30 mN / m. In this case, the dispersion exhibits excellent coating properties and homogeneity. Furthermore, in this method, friction between the coating roll and metering roll and the wetted part of the dispersion is easily suppressed, preventing minute foaming of the dispersion and facilitating the formation of a dense polymer layer with superior surface appearance.

[0043] When the liquid dispersion medium constituting this dispersion is water, the pH of this dispersion is more preferably 8 to 10 from the viewpoint of improving long-term storage. The pH of this dispersion can be adjusted by a pH adjusting agent (amine, ammonia, citric acid, etc.) or a pH buffering agent (tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium bicarbonate, ammonium carbonate, ammonium acetate, etc.).

[0044] In this method, the dispersion described above is supplied to a liquid reservoir located behind the coating roll, which is composed of a rotating coating roll and a metering roll positioned above the coating roll and equipped with a doctor knife on the rear side of the coating roll. The dispersion is passed through the gap between the coating roll and the metering roll and coated onto the surface of a long substrate running on a rotating backup roll positioned in front of the coating roll, thereby obtaining a long laminated substrate having a substrate layer and a coating layer for forming a polymer layer on the surface of the substrate layer by melt firing. The coating method with this configuration falls under the category of the reverse coater method, in which a coating roll carrying the dispersion is rotated in the opposite direction to the direction of travel of the long substrate. A backup roll, positioned directly opposite the coating roll with the long substrate in between, applies pressure to transfer the dispersion. In this configuration, the dispersion is supplied to the coating roll from a liquid reservoir located on the rear side of the coating roll. The doctor knife plays the role of scraping off excess dispersion adhering to the metering roll. More specifically, an example of a device to which this Act can be applied is the top-feed reverse coater type coating apparatus disclosed in Japanese Patent Publication No. 6-2250.

[0045] In this method, the width of the gap between the coating roll and the metering roll described above is greater than the product of the thickness of the polymer layer and the reciprocal of the content ratio of F particles in the dispersion. Specifically, it is preferable that the width of the gap is greater than 1 and less than or equal to 1.2 times the product of the thickness of the polymer layer (μm) and the reciprocal of the content ratio of F particles in the dispersion (for example, if the content of F particles in the dispersion is 40% by mass, the reciprocal is 1 / 0.4 = 2.5).

[0046] In this method, the surface hardness of at least one of the coating roll, metering roll, and backup roll is 60 to 75 degrees. When the surface hardness is within the above range, when this method is performed by increasing the peripheral speed of the rolls, it is possible to prevent the incorporation of bubbles into the dispersion due to air entrapment and the occurrence of unevenness in the coating layer due to minute vibrations of the coating roll, and a long laminated substrate having a coating layer with a uniform film thickness and excellent surface appearance can be obtained with high productivity. Preferably, the surface hardness of the backup roll is 60 to 75 degrees, and it is preferable that the surface hardness of the coating roll, metering roll, and backup roll is all 60 to 75 degrees. The surface hardness of each roll can be adjusted by selecting the material of the lining rubber for each roll. Examples of such rubbers include urethane rubber, nitrile butadiene rubber, and chloroprene rubber, which have excellent wear resistance. In this specification, the surface hardness of a roll refers to the spring hardness (Hs) under normal conditions, measured according to the provisions of JIS K 6301 (Physical Testing Methods for Vulcanized Rubber), 5.2.

[0047] Examples of long substrates include heat-resistant substrates such as films of heat-resistant resins like polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide-imide, liquid crystalline polyester, and tetrafluoroethylene polymers; and prepreg substrates (precursors of fiber-reinforced resin substrates). The long substrate is preferably a heat-resistant substrate, and more preferably a polyimide film. The thickness of the long film substrate is preferably 10 to 200 μm. The ten-point average surface roughness of the long substrate is preferably 0.01 to 0.05 μm. The surface of the long substrate may be surface-treated with a silane coupling agent or plasma-treated. Preferred silane coupling agents include those having functional groups such as 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-isocyanatetopropyltriethoxysilane.

[0048] It is preferable to heat the coating layer on the surface of the long laminated substrate to remove the liquid dispersion medium, and then heat it further to melt and sinter the F polymer to form a polymer layer containing the F polymer (hereinafter also referred to as the "F layer"). When removing the liquid dispersion medium, heating is preferably carried out at 100-200°C for 0.1-30 minutes. During this heating, it is not necessary to completely remove the liquid dispersion medium; it is sufficient to remove it to the extent that the layer formed by the packing of F particles can maintain a self-supporting film. In addition, during heating, air may be blown on to promote the removal of the liquid dispersion medium by air drying.

[0049] When heating the F polymer during firing, it is preferable to do so at a temperature above the melting point of the F polymer, and more preferably at 360-400°C for 0.1-30 minutes. Examples of heating devices for each heating process include ovens and forced-air drying ovens. The heat source in the device may be a contact-type heat source (hot air, hot plate, etc.) or a non-contact heat source (infrared radiation, etc.). Furthermore, each heating process may be carried out under normal pressure or under reduced pressure. Furthermore, the atmosphere used for each heating process may be either an air atmosphere or an inert gas atmosphere (such as helium, neon, argon, or nitrogen).

[0050] The F layer is formed by the coating and heating steps of the dispersion according to this method. These steps may be performed once or repeated two or more times. For example, the dispersion may be coated onto the surface of a long substrate using this method and heated to form the F layer, and then the dispersion may be coated onto the surface of the F layer using this method and heated to form a second F layer. Alternatively, the dispersion may be coated onto the surface of a long substrate using this method and heated to remove the liquid dispersion medium, and then the dispersion may be coated onto the surface using this method and heated to form the F layer.

[0051] In this method, the dispersion may be applied to only one surface of the long substrate, or to both surfaces of the long substrate. In the former case, a long laminated substrate is obtained having a long substrate layer and an F layer on one surface of the long substrate layer. In the latter case, a long laminated substrate is obtained having a long substrate layer and an F layer on both surfaces of the long substrate layer. In this method, a long laminate having a long substrate and an F layer formed from a coating layer on both sides of the long substrate can preferably be obtained in one of the following ways. In other words, a coating layer is formed on one side of a long substrate using this method, and after drying and firing, an F layer is formed on one side of the long substrate. Then, the long substrate having the obtained F layer is wound up, and then a coating layer is formed on the substrate surface opposite to the side with the F layer using this method, and after further drying and firing, a long laminate having an F layer on both sides of the substrate is obtained. Alternatively, by this method, a long substrate having a coating layer formed from this dispersion is obtained, and by further drying and firing, a long substrate having an F layer on its surface is obtained, and while the long substrate having the F layer is running through another apparatus to which this method can be applied, this dispersion is applied by the other apparatus to the surface of the long substrate opposite to the surface having the F layer, and by further drying and firing, a long laminate having an F layer on both sides of the substrate is obtained. Alternatively, the dispersion may be applied to both sides of a long substrate using multiple apparatus capable of applying this method to obtain a long laminated substrate having a coating layer formed from the dispersion on both surfaces of the long substrate, and then dried and fired to obtain a long laminate having an F layer on both sides of the substrate. A long laminate having an F layer on both the long base material layer and the long base material's surface is less prone to warping, thus offering superior handling during processing. The thickness of the F layer varies depending on the application of the long laminate, but it is preferably 20 μm or more, and preferably in the range of 20 to 150 μm. Furthermore, by separating the substrate from such a long laminate, a sheet containing F polymer can be obtained.

[0052] The dielectric constant of the F layer is preferably 2.4 or less, and more preferably 2.0 or less. Furthermore, the dielectric constant of the F layer is preferably greater than 1.0. The dielectric loss tangent of the F layer is preferably 0.0022 or less, and more preferably 0.0020 or less. Furthermore, the dielectric loss tangent of the F layer is preferably greater than 0.0010. The thermal conductivity of the F layer is preferably 1 W / m·K or higher, and more preferably 3 W / m·K or higher. Note that the thermal conductivity of the F layer refers to the thermal conductivity of the F layer in the in-plane direction. The linear expansion coefficient of the F layer is preferably 100 ppm / °C or less, and more preferably 80 ppm / °C or less. The lower limit of the linear expansion coefficient of the F layer is 30 ppm / °C. Note that the linear expansion coefficient refers to the value measured for the linear expansion coefficient of the test specimen in the range of 25°C to 260°C, according to the measurement method specified in JIS C 6471:1995. The peel strength between the F layer and the long substrate is preferably 10 to 100 N / cm.

[0053] Suitable examples of long laminated substrates obtained by this method include polyimide films and multilayer films having F layers on both surfaces of the polyimide film. Such long laminated substrates are suitable as printed circuit board materials because they have an F layer with excellent electrical properties. Specifically, they can be used in the manufacture of printed circuit boards as flexible metal-clad laminates or rigid metal-clad laminates, and are particularly suitable for use in the manufacture of flexible printed circuit boards as flexible metal-clad laminates. In the manufacture of such printed circuit boards, an interlayer insulating film may be formed on the transmission circuit, a solder resist may be laminated on the transmission circuit, or a coverlay film may be laminated on the transmission circuit.

[0054] Such long laminated substrates are useful for antenna components, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, heat dissipation components, and the like. Specifically, these include wire insulation materials (aircraft wires, etc.), electrical insulation tapes, insulating tapes for oil drilling, printed circuit board materials, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, furniture, car dashboards, covers for home appliances, sliding components (load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, food transport belts, etc.), tools (shovels, files, drills, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, dies, toilets, container insulation materials, heat dissipation substrates for power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, and power MOS It is useful in FETs, CPUs, heat sinks, metal heat sinks, blades for wind turbines, wind power generation equipment, and aircraft, computer and display casings, electronic device materials, automotive interiors and exteriors, sealing materials for processing machines and vacuum ovens that perform heat treatment under low oxygen conditions, plasma processing equipment, heat dissipation components in processing units such as sputtering and various dry etching equipment, and as electromagnetic shielding. The long laminated substrates formed by this method are particularly useful as electronic substrate materials such as flexible printed circuit boards and rigid printed circuit boards, as well as protective films and heat dissipation substrates for automobiles.

[0055] Although the present invention has been described above, it is not limited to the configuration of the embodiments described above. For example, the present method may have additional steps in the configuration of the above embodiment, or may be replaced by any other steps that produce a similar effect. [Examples]

[0056] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. 1. Preparation of each component [F Polymer] F particle 1: Contains TFE units, NAH units, and PPVE units in the following order: 97.9 mol%, 0.1 mol%, and 2.0 mol%, respectively, with a carbonyl group containing a main chain of 1 × 10¹⁶ carbon atoms. 6 Particles of tetrafluoroethylene polymer (melting temperature: 300℃) with 1000 particles per unit (D50: 2.0μm, specific surface area: 7m²) 2 / g) [Nonionic surfactants] Surfactant 1: An alcohol-based surfactant with an acetylenediol-based skeleton and an HLB value of 3. Surfactant 2: A silicone-based surfactant with a polysiloxane chain in the main chain and polyethylene oxide groups in the side chains, with an HLB value of 13. [Cellulose ether] 1 cellulose ether substitution degree 2.4 hydroxyethylcellulose [Aromatic polymers] Varnish 1: Water-based varnish containing an aromatic polyamide-imide (PAI1) precursor (product name "HP-1000", manufactured by Showa Denko Materials Co., Ltd.) [Base material] Substrate 1: Aromatic polyimide film with a thickness of 25 μm (PI Advanced Materials "FG-100")

[0057] 2. Examples of dispersion preparation [Manufacturing Example 1] F particles 1, surfactant 1, surfactant 2, cellulose ether 1, varnish 1, and water were stirred in a rotary-rotating stirrer to obtain dispersion 1 (viscosity: 1000 mPa·s, F particle 1 content: 33% by mass (content ratio: 0.33)) containing F particles 1 (33 parts by mass), surfactant 1 (3 parts by mass), surfactant 2 (3 parts by mass), cellulose ether 1 (0.1 parts by mass), PAI 1 (0.1 parts by mass), and water (60.8 parts by mass). [Manufacturing Example 2] Dispersion 2 (viscosity: 5000 mPa·s, F particle 1 content: 33% by mass (content ratio: 0.33)) was obtained in the same manner as in Production Example 1, except that the amount of cellulose ether 1 was changed.

[0058] [Manufacturing Example 3] Dispersion 3 (viscosity: 10,000 mPa·s, F particle 1 content: 33% by mass (content ratio: 0.33)) was obtained in the same manner as in Production Example 1, except that the amount of cellulose ether 1 was changed. [Manufacturing Example 4] Dispersion 4 (viscosity: 3000 mPa·s, F particle 1 content: 50% by mass (content ratio: 0.5)) was obtained in the same manner as in Production Example 1, except that the amount of F particle 1 was changed.

[0059] 3. Manufacturing of long laminated substrates <Example 1> A coating apparatus comprising a rotating coating roll and a metering roll positioned above the coating roll and equipped with a doctor knife on the rear side of the coating roll, supplies a coating liquid to a liquid reservoir provided on the rear side of the coating roll, allows the coating liquid to pass through the gap between the coating roll and the metering roll, and coats the surface of a long substrate running on a rotating backup roll positioned in front of the coating roll, is used to manufacture a long laminated substrate 1 having a coating layer of dispersion liquid 1 on the surface of the substrate 1 by running the substrate 1 through a roll-to-roll process. In this setup, the gap between the coating roll and the metering roll was set to 100 μm, and the surface hardness of the backup roll was set to 70 degrees. Subsequently, the long laminated substrate 1 obtained above was passed through a ventilated drying oven (furnace temperature 150°C) for 3 minutes to remove water and form a dry film, and then passed through a far-infrared furnace (furnace temperature 300°C near the inlet and outlet, furnace temperature 360°C near the center) for 5 minutes to melt and calcine the F particles 1. As a result, a polymer layer containing molten F particles 1 and PAI 1 is formed on one surface of the base material 1, and a long laminate 1 in which the polymer layer and the base material 1 layer are formed in this order is obtained by a roll-to-roll process. The thickness of the polymer layer in the long laminate 1 is 30 μm, and the product of the polymer layer thickness and the reciprocal of the content ratio of F particles 1 in the dispersion 1 (hereinafter also referred to as "product") is calculated to be 90.9. That is, the width of the gap is 1.1 times this product.

[0060] <Examples 2-6> Long laminated substrates 2 to 6 were manufactured in the same manner as in Example 1, except that dispersion 1 was changed to dispersions 2 to 4, or the gap width between the coating roll and the metering roll and the surface hardness of the backup roll were changed to the values ​​shown in Table 1. The thickness of the polymer layer in long laminates 2 to 6, obtained by firing the F polymer, was 30 μm in each case. The relationship between the volume and the gap width in each example is shown in Table 1.

[0061] 4. Evaluation of long laminated substrates For each polymer layer of the long laminates 1 to 6, the presence or absence of streaky patterns in the flow direction was visually observed, and the surface properties were evaluated according to the following criteria. The results are shown in Table 1. [Evaluation Criteria] ○: No streaks appear in the coating length of 1 to 100 m, and the surface is highly smooth. △: While streaks appear at the edges in the coated length of 1 to 100m, the overall surface smoothness is high. ×: Streaks are present throughout the coating area from 1 to 100m.

[0062] [Table 1] [Industrial applicability]

[0063] The long laminated substrate obtained by this method exhibits the properties of F polymer to a high degree, and has a polymer layer with particularly excellent surface appearance, making it applicable to various uses such as flexible printed circuit boards.

Claims

1. A method for manufacturing a long laminated substrate having a substrate layer and a coating layer for forming a polymer layer on the surface of the substrate layer by melt firing, comprising: supplying a dispersion containing tetrafluoroethylene polymer particles and a liquid dispersion medium to a liquid reservoir provided on the rear side of the coating roll, the dispersion passing through the gap between the coating roll and the metering roll, and coating the surface of a long substrate running on a rotating backup roll provided on the front side of the coating roll, the method comprising: supplying a dispersion containing tetrafluoroethylene polymer particles and a liquid dispersion medium to a liquid reservoir provided on the rear side of the coating roll, the dispersion passing through the gap between the coating roll and the metering roll, and coating the surface of a long substrate running on a rotating backup roll provided on the front side of the coating roll, the method comprising: The viscosity of the dispersion is 100 to 5000 mPa·s and the content of the tetrafluoroethylene polymer particles in the dispersion is 15 to 45% by mass. The width of the gap (in μm) is greater than the product of the thickness of the polymer layer (in μm) and the reciprocal of the content ratio of the tetrafluoroethylene polymer particles in the dispersion. A manufacturing method wherein at least one of the coating roll, the metering roll, and the backup roll has a surface hardness of 70 to 75 degrees.

2. The manufacturing method according to claim 1, wherein the surface hardness of the coating roll, the metering roll, and the backup roll is all 70 to 75 degrees.

3. The manufacturing method according to claim 1, wherein the tetrafluoroethylene polymer particles are heat-meltable tetrafluoroethylene polymer particles having an average particle diameter of 0.3 μm or more and less than 10 μm.

4. The manufacturing method according to claim 1, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group.

5. The manufacturing method according to claim 1, wherein the liquid dispersion medium is at least one selected from the group consisting of water, amides, ketones, and esters.

6. The manufacturing method according to claim 1, wherein the dispersion further contains at least one nonionic surfactant selected from the group consisting of alcohol-based surfactants and silicone-based surfactants.

7. The manufacturing method according to claim 1, wherein the dispersion further contains at least one thickening agent selected from the group consisting of acrylic acid polymers, vinyl alcohol polymers, and cellulose polymers.

8. The manufacturing method according to claim 1, wherein the dispersion further contains an alcohol having 1 to 6 carbon atoms.

9. The manufacturing method according to claim 1, wherein the surface tension of the dispersion is 20 to 30 mN / m.

10. The manufacturing method according to claim 1, wherein the long laminated substrate has the polymer layer on both surfaces of the long substrate.

11. The manufacturing method according to claim 1, wherein the long substrate is a heat-resistant substrate.

12. The manufacturing method according to claim 11, wherein the heat-resistant substrate is a polyimide film.

13. The manufacturing method according to any one of claims 1 to 12, wherein the width of the gap is greater than 1 and less than or equal to 1.2 times the product of the thickness of the polymer layer and the content ratio of the tetrafluoroethylene polymer particles in the dispersion.

14. The manufacturing method according to claim 13, wherein the thickness of the polymer layer is 20 μm or more.

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