Dispersion, method for producing a polymer-coated substrate, and polymer-coated substrate

Abstract

The present invention provides a dispersion containing a tetrafluoroethylene polymer that is easy to handle due to its excellent dispersibility and liquid properties, and that can form a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesive properties, etc., and a polymer-coated substrate equipped with the polymer layer. [Solution] A dispersion comprising tetrafluoroethylene polymer particles, a dispersant, and a polar dispersion medium, wherein the dispersant is a (meth)acrylate-based silicone polymer containing the following units [I] and [II], and has a thixotropic ratio of 2.0 or less. JPEG2026125441000011.jpg25166 (In formula [I], R 1 R represents a hydrogen atom or a methyl group, and A represents an organopolysiloxane-containing group. In formula [II], R 2 (where B represents a hydrogen atom or a methyl group, and B represents a polyoxyalkylene group-containing group.)

Description

[Technical Field]

[0001] The present invention relates to a dispersion containing a tetrafluoroethylene polymer, a method for producing a polymer-coated substrate using the dispersion, and the polymer-coated substrate. [Background technology]

[0002] Tetrafluoroethylene polymers such as polytetrafluoroethylene (PTFE) exhibit excellent physical properties such as electrical properties, water and oil repellency, chemical resistance, and heat resistance, and are used in a variety of applications. Furthermore, in recent years, in order to cope with the increasing speed and frequency of mobile communication devices such as mobile phones, insulating materials for printed circuit boards of communication devices require materials with high thermal conductivity, low coefficient of linear expansion, low dielectric constant, and low dielectric loss tangent. Tetrafluoroethylene polymers, which have low dielectric constant and low dielectric loss tangent, have attracted attention. Compositions containing particles of tetrafluoroethylene polymers, in particular, have attracted special attention in recent years. Tetrafluoroethylene polymer particles generally have poor dispersibility in non-aqueous solvents, so dispersants are often included to improve dispersibility. However, when fluorine compounds are used as dispersants, the smoothness and hydrophilicity of the molded product surface tend to decrease when forming molded products such as coatings (polymer layers) from such compositions, and the adhesion between the conductive layer and the insulating layer tends to decrease, so improvements are being considered. Patent Document 1 proposes a composition comprising tetrafluoroethylene polymer particles, a specific compound that does not contain fluorine atoms, and a non-aqueous solvent. On the other hand, Patent Document 2 discloses an emulsifier consisting of a diblock type copolymer having specific copolymer block units and terminal structures. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2024 / 053554 [Patent Document 2] Japanese Patent Publication No. 2021-183314

Summary of the Invention

Problems to be Solved by the Invention

[0004] The dispersant proposed in the composition disclosed in Patent Document 1 is excellent in the dispersibility of tetrafluoroethylene-based polymer particles, but there is still room for improvement in the dispersibility and the liquid physical properties of the composition itself. The emulsifier disclosed in Patent Document 2 is considered suitable as a raw material for water-in-oil type emulsified compositions, particularly cosmetics such as emulsions, but there is no knowledge for the purpose of improving the dispersibility of tetrafluoroethylene-based polymer particles. In addition, for printed circuit board materials, in addition to their electrical properties, it is necessary to highly balance their heat resistance, mechanical properties, and the adhesiveness (adhesion) between the conductive layer and the insulating layer, and it is necessary to consider the affinity and uniform dispersibility of the components constituting the composition. The inventors of the present invention have found that a dispersion liquid containing particles of a tetrafluoroethylene-based polymer containing a specific dispersant is excellent in dispersibility and liquid physical properties, easy to handle, and can form a dense polymer layer (film) excellent in mechanical properties, heat resistance, electrical properties (such as low linear expansion coefficient, low dielectric constant, and low dielectric tangent), adhesiveness, etc., and thus have arrived at the present invention. An object of the present invention is to provide a dispersion liquid containing a tetrafluoroethylene-based polymer, which is excellent in dispersibility and liquid physical properties, easy to handle, and can form a polymer layer excellent in mechanical properties, heat resistance, electrical properties, adhesiveness, etc., and a polymer layer-provided substrate provided with the polymer layer.

Means for Solving the Problems

[0005] The present invention has the following aspects. 〔1〕 A dispersion liquid containing particles of a tetrafluoroethylene-based polymer, a dispersant, and a polar dispersion medium, where the dispersant is a (meth)acrylate-based silicone polymer containing the following unit [I] and the following unit [II], and the thixotropic ratio is 2.0 or less.

[0006]

Chemical formula

[0007] (In formula [I], R , 4 , , 4 , represents a hydrogen atom or a methyl group, and A represents an organopolysiloxane-containing group. In formula [II], R 2 represents a hydrogen atom or a methyl group, and B represents a polyoxyalkylene group-containing group.) 〔2〕 The dispersion liquid according to 〔1〕, wherein the tetrafluoroethylene-based polymer contains a thermally fusible tetrafluoroethylene-based polymer having a carbonyl group-containing group. 〔3〕 The dispersion liquid according to 〔1〕 or 〔2〕, wherein the content of the particles of the tetrafluoroethylene-based polymer is 20% by mass or more. 〔4〕 The dispersion liquid according to any one of 〔1〕 to 〔3〕, wherein the average particle diameter of the particles of the tetrafluoroethylene-based polymer is 0.1 μm or more and 10 μm or less. 〔5〕 The dispersion liquid according to any one of 〔1〕 to 〔4〕, wherein the organopolysiloxane-containing group represented by A in the unit [I] is a group having a linear organopolysiloxane structure represented by the following formula (1).

[0008]

Chemical formula

[0009] (In formula (1), m represents 0 to 100, Z represents an alkylene group, and R 3 represents an alkyl group or a phenyl group, and R 3a represents an alkyl group, an alkoxy group or a phenyl group.) 〔6〕 The dispersion liquid according to any one of 〔1〕 to 〔(5)〕, wherein the polyoxyalkylene group-containing group represented by B in the unit [II] is a group having an oxyethylene unit represented by the following formula (2). -O(CH2CH2O)n-R 4 (2) (In the formula, n represents 1 to 100, and R 4 represents an alkyl group or a hydrogen atom.) 〔7〕 The dispersion liquid according to any one of 〔1〕 to 〔6〕, wherein the dispersant is a (meth)acrylate-based silicone diblock polymer having a polymer block composed of the unit [I] and a polymer block composed of the unit [II]. 〔8〕 The dispersion liquid according to 〔7〕, wherein the terminal structure of the polymer block composed of the unit [I] is represented by the following formula [III], and the terminal structure of the polymer block composed of the unit [II] is represented by the following formula [IV], and it is a (meth)acrylate-based silicone diblock polymer.

[0010]

Chemical formula

[0011] (In formula [III], R 5 represents an alkyl group, and R 6 represents a hydrogen atom or an alkyl group. In formula [IV], R 7 represents a hydrogen atom or a methyl group, and X represents a polyoxyalkylene group-containing group.) 〔9〕 The ratio (n 1 / n 2 ) of the number of repeating units n 2 of the unit [II] to the number of repeating units n 1 of the unit [I] in the (meth)acrylate-based silicone polymer is 0.02 to 10. The dispersion liquid according to any one of 〔1〕 to 〔8〕. 〔10〕 The number average molecular weight (Mn) of the (meth)acrylate-based silicone polymer is 2000 to 25000, and the molecular weight distribution (Mw / Mn) is 1.00 to 3.00. The dispersion liquid according to any one of 〔1〕 to 〔9〕. 〔11〕 The dispersion liquid according to any one of 〔1〕 to 〔10〕, wherein the polar dispersion medium is one or more non-aqueous polar solvents selected from the group consisting of amide, ketone, and ester. 〔12〕 The content of the dispersant with respect to the particles of the tetrafluoroethylene-based polymer is 10% by mass or less. The dispersion liquid according to any one of 〔1〕 to 〔11〕. 〔13〕 The dispersion liquid according to any one of 〔1〕 to 〔12〕, having a viscosity of 1000 mPa or less.

[14] A method for producing a polymer-coated substrate, comprising: coating the surface of a substrate with any of the dispersions from [1] to

[13] to form a coating layer made of the dispersion on the surface of the substrate; and heating the substrate having the coating layer to form a polymer layer containing the tetrafluoroethylene polymer on the surface of the substrate.

[15] A polymer-coated substrate having a polymer layer containing the tetrafluoroethylene polymer, formed from any dispersion of [1] to

[13] . [Effects of the Invention]

[0012] According to the present invention, a dispersion liquid containing a tetrafluoroethylene polymer is provided that is easy to handle due to its excellent dispersibility and liquid properties, and can form a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesive properties, etc. A polymer-coated substrate (laminated body) having this polymer layer can be effectively used, for example, as a printed circuit board material. [Modes for carrying out the invention]

[0013] 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 composition using a B-type viscometer under conditions of 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 a value calculated by dividing the viscosity η1 of the composition, 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 number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the dispersant were measured using a GPC (HLC-8320GPC, manufactured by Tosoh Corporation) under the following measurement conditions, and were expressed as values ​​equivalent to standard polystyrene. Columns (all manufactured by Tosoh Corporation): TSK Guard Column SuperH-H (4.6mm I.D. × 35mm) TSKgel SuperH2500 (filler particle size 3.0 μm, 6 mm I.D. × 150 mm) TSKgel SuperHM-N (filler particle size 3.0 μm, 6 mm I.D. × 150 mm) Eluent: Tetrahydrofuran (THF) Flow rate: 0.6ml / min Measurement temperature: 40℃ Sample concentration: 0.3% by mass (THF solution) Sample injection volume: 50 μl Detector: Differential refractometer (RI) 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." "(Meth)acrylate" is a general term encompassing acrylate, methacrylate, and both.

[0014] The present invention comprises tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") particles (hereinafter also referred to as "F particles"), a dispersant, and a polar dispersion medium. The dispersant is a (meth)acrylate-based silicone polymer (hereinafter also referred to as "the dispersant polymer") containing the following units [I] and [II], and the dispersion (hereinafter also referred to as "the dispersion") has a thixotropy ratio of 2.0 or less.

[0015] [ka]

[0016] (In formula [I], R 1 R represents a hydrogen atom or a methyl group, and A represents an organopolysiloxane-containing group. In formula [II], R 2 (where B represents a hydrogen atom or a methyl group, and B represents a polyoxyalkylene group-containing group.)

[0017] This dispersion has excellent dispersibility and liquid properties, making it easy to handle. Furthermore, a polymer layer with excellent mechanical properties, heat resistance, electrical properties, and adhesive properties based on F polymer can be formed from this dispersion. A polymer-coated substrate (laminated) equipped with this polymer layer can be effectively used in various applications that take advantage of these properties, and can be effectively used as a printed circuit board material, for example. The reason why this dispersion has excellent dispersibility and liquid properties, is easy to handle, and can form a polymer layer with excellent mechanical properties, heat resistance, electrical properties, and adhesiveness based on F polymer is not entirely clear, but it can be thought to be as follows.

[0018] When a non-fluorinated dispersant is further added to a dispersion containing F particles in a polar solvent, its surfactant properties need to be examined in detail. Specifically, if the non-fluorinated dispersant is too hydrophobic, it will interact well with the F particles but will have reduced interaction with the polar solvent. Conversely, if it is too hydrophilic, it will interact well with the polar solvent but will have reduced interaction with the F particles. The inventors have also found that the surfactant properties of the non-fluorinated dispersant affect the liquid properties (thixotropy ratio) of the dispersion containing F particles once it has been prepared. The dispersant polymer contained in this dispersion has a rigid polymer main chain derived from a (meth)acryloyl group, and has a mild hydrophobic organopolysiloxane group and a mild hydrophilic polyoxyalkylene group as separate units in the polymer side chain. Therefore, the conformation of this dispersant polymer in the dispersion tends to result in an independent orientation order of mild hydrophobic and hydrophilic parts, and it is presumed that the affinity between the hydrophobic parts and F particles and the affinity between the hydrophilic parts and polar solvents are both increased and balanced. As a result, this dispersion has excellent dispersibility (dispersion stability) and liquid properties, making it easy to handle. Furthermore, when forming molded products such as coating films (polymer layers) from this dispersion, the dispersant polymer also functions as a binder component for the F particles during heating. Therefore, it is believed that the molded product is highly endowed with properties based on the F polymer (mechanical properties, heat resistance, electrical properties, etc.).

[0019] The F polymer in this invention is a polymer containing units based on tetrafluoroethylene (hereinafter also referred to as "TFE") (hereinafter also referred to as "TFE units"). The F polymer is preferably thermally meltable. Here, a thermally meltable polymer means a polymer that, under a load of 49N, has a temperature at which the melt flow velocity is 1 to 1000 g / 10 min. The melting temperature of the F polymer is preferably 200°C or higher, and more preferably 260°C or higher. The melting temperature of the F polymer is preferably 325°C or lower, and more preferably 320°C or lower. The melting temperature of the F polymer is preferably between 200°C and 320°C. In this case, the dispersion has good processability, and the polymer layer formed from the dispersion has good heat resistance.

[0020] 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.

[0021] The F polymer is preferably 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. PAVE is preferably CF2=CFOCF3, CF2=CFOCF2CF3, and CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"), with PPVE being more preferred.

[0022] 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 handling properties, and the polymer layer formed from the dispersion is likely to exhibit excellent physical properties such as heat resistance and electrical properties (low coefficient of thermal expansion, low dielectric constant, and low dielectric loss tangent). 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.), formyl groups, halogenoformyl groups, urethane groups (-NHC(O)O-), carbamoyl groups (-C(O)-NH2), ureido groups (-NH-C(O)-NH2), oxamoyl groups (-NH-C(O)-C(O)-NH2), 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.

[0023] 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.

[0024] 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.

[0025] The F particles contained in this dispersion are particles containing F polymer, and it is preferable that they consist of F polymer. The D50 of the F particles is preferably 0.1 μm or more and 10 μm or less. 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 1.0 μm or more, more preferably 1.5 μm or more. The D50 of the F particles is preferably 6 μm or less, more preferably 4 μm or less. Furthermore, the D90 of the F particles is preferably 8 μm or less, and more preferably 6 μm or less. When the D50 and D90 of the F particles are within the above range, the above-described mechanism of action is more easily expressed, and it is easier to obtain a dispersion that is easy to handle, has excellent dispersibility and liquid properties, and can form a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc., based on the F polymer. One type of F particle may be used, or two or more types may be used.

[0026] The specific surface area of ​​F particles is 25 m². 2 Preferably, it should be less than or equal to / g, and 1 to 25m 2 It is preferable that the amount is / g, and 6-15m 2 / g is more preferable. When the specific surface area of ​​the F particles is within the above range, the dispersion is easily obtained, which has excellent dispersibility and liquid properties, is easy to handle, and forms a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc., based on the F polymer, due to the mechanism of action described above.

[0027] The dispersant polymer contained in this dispersion is a (meth)acrylate-based silicone polymer containing the following units [I] and [II].

[0028] [ka]

[0029] In formula [I], R 1 represents a hydrogen atom or a methyl group, and A represents an organopolysiloxane-containing group. In formula [II], R 2 represents a hydrogen atom or a methyl group, and B represents a polyoxyalkylene group-containing group.

[0030] The organopolysiloxane-containing group represented by A in unit [I] may be a group having a linear organopolysiloxane structure or an organopolysiloxane-containing group having a dendritic branched structure, with a group having a linear organopolysiloxane structure being preferred. In particular, a group having a linear organopolysiloxane structure represented by the following formula (1) is more preferred, and the dimethylpolysiloxane unit [(-(CH3)2SiO 2 / 2 It is even more preferable to have -).

[0031] [ka]

[0032] (In formula (1), m represents 1 to 100, Z represents an alkylene group, R 3 is an alkyl group or a phenyl group, R 3a (This represents an alkyl group, alkoxy group, or phenyl group.) The alkylene group represented by Z can be a linear, branched, or cyclic group having 2 to 12 carbon atoms, such as a methylene group or a propylene group, with the propylene group being preferred. R 3 and R 3a Examples of alkyl groups represented by each include linear, branched, or cyclic alkyl groups having 1 to 10 carbon atoms, such as a methyl group and an ethyl group, with the methyl group being preferred. R 3a Examples of alkoxy groups represented by include alkyl groups having 1 to 10 carbon atoms, such as the methoxy group. 3 R 3a They may be the same or different. m is a positive number between 1 and 100, preferably between 10 and 40.

[0033] The polyoxyalkylene group-containing group represented by B in unit [II] is preferably a group having an oxyethylene unit, as shown in the following formula (2). -O(CH2CH2O)nR 4 (2) (In the formula, n represents 1 to 100, R 4 (This represents an alkyl group or a hydrogen atom.) R 4 Examples of alkyl groups represented by include linear, branched, or cyclic alkyl groups having 1 to 10 carbon atoms, such as methyl groups and ethyl groups. n is a positive number between 1 and 100, preferably between 5 and 80.

[0034] The dispersant polymer may have units [I] and [II] randomly or alternately, and may have polymer blocks composed of units [I] and polymer blocks composed of units [II]. In particular, it is more preferable that the dispersant polymer is a (meth)acrylate-based silicone diblock polymer having polymer blocks composed of unit [I] and polymer blocks composed of unit [II], from the viewpoint of easily exhibiting the above-described mechanism of action, the dispersion has excellent dispersibility and liquid properties and is easy to handle, and easily forms a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc. based on the F polymer. A polymer block composed of unit [I] may have a group having a linear organopolysiloxane structure represented by the same formula (1), or a group having a linear organopolysiloxane structure represented by a different formula (1). A polymer block composed of unit [II] may have a polyoxyalkylene group-containing group represented by the same formula (2), or a polyoxyalkylene group-containing group represented by a different formula (2).

[0035] Furthermore, it is even more preferable that the (meth)acrylate-based silicone diblock polymer is such that the terminal structure of the polymer block composed of unit [I] is represented by the following formula [III], and the terminal structure of the polymer block composed of unit [II] is represented by the following formula [IV].

[0036] [ka]

[0037] (In formula [III], R 5 R represents an alkyl group. 6 R represents a hydrogen atom or an alkyl group. In formula [IV], R 7 (where represents a hydrogen atom or a methyl group, and X represents a polyoxyalkylene group-containing group.) R 5 and R 6 The alkyl group represented is preferably an alkyl group having 1 to 4 carbon atoms, and examples include a methyl group, an ethyl group, a propyl group, and a butyl group. The polyoxyalkylene group-containing group represented by X is the same group as the polyoxyalkylene group-containing group represented by B described above. In other words, the dispersant polymer is preferably a diblock polymer of a specific structure, and is preferably a graft polymer having A (organopolysiloxane-containing group) in the side chain of unit [I] and B (polyoxyalkylene group-containing group) in unit [II].

[0038] In this dispersant polymer, the number of repeating units of unit [I] is n. 1 and the number of repeating units of unit [II] n 2 Each of these values ​​is preferably between 1 and 50, more preferably between 1 and 20, and even more preferably between 3 and 10. Furthermore, the number of repeating units of the unit [I] in this dispersant polymer is n. 1 Number of repeating units n with the aforementioned unit [II] 2 The ratio (n 2 / n 1 The value of ) is preferably 0.02 to 10, and more preferably 0.05 to 5.

[0039] The number-average molecular weight (Mn) of the dispersant polymer is preferably 2,000 to 25,000, and more preferably 3,000 to 15,000. Furthermore, the molecular weight distribution (Mw / Mn) of the dispersant polymer is preferably 1.00 to 3.00, and more preferably 1.05 to 1.60. Among these, it is even more preferable that the Mn of the dispersant polymer is 2,000 to 25,000 and the Mw / Mn is 1.00 to 3.00. This dispersant polymer may be used individually or in combination of two or more types.

[0040] The polar dispersion medium contained in this dispersion is a compound that is liquid at atmospheric pressure and 25°C, and preferably a compound with a boiling point of 50 to 240°C. One type of polar dispersion medium may be used, or two or more types may be used. When two or more polar dispersion mediums are used, it is preferable that the two or more polar dispersion mediums are mutually compatible. Examples of polar dispersion media include water and polar solvents such as alcohols, ethers, amides, ketones, and esters. In particular, it is preferable that the polar dispersion media be a non-aqueous polar solvent, and more preferably at least one non-aqueous polar solvent selected from the group consisting of 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. Among these, N-methyl-2-pyrrolidone is even more preferred.

[0041] The content of F particles in this dispersion is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more. The content of F particles is preferably 55% by mass or less, and more preferably 50% by mass or less. The content of the dispersant polymer in this dispersion is preferably in the range of 1 to 15% by mass relative to the total amount of the dispersion. Furthermore, the content of the dispersant polymer relative to F particles in this dispersion is preferably 10% by mass or less. The content of the polar dispersion medium in this dispersion is preferably 25% by mass or more, and more preferably 40% by mass or more. The content of the polar dispersion medium is preferably less than 70% by mass, and more preferably 65% ​​by mass or less. Furthermore, the content of the polar dispersion medium in this dispersion is preferably 60 to 180% by mass relative to the content of F particles.

[0042] This dispersion may further contain other nonionic surfactants, such as glycol-based surfactants and acetylene-based surfactants, that are different from the dispersant polymer described above, as long as they do not impair the effects of the present invention.

[0043] 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. 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. If the dispersion further contains inorganic particles, the inorganic particle content in the dispersion is preferably 1 to 25% by mass.

[0044] 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 polar dispersion medium constituting the dispersion. 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. If this dispersion further contains other resins, the content of the other resins relative to the F particles is preferably 1 to 25% by amount.

[0045] This dispersion may further contain additives such as thixotropic agents, viscosity modifiers, defoamers, dehydrators, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, and flame retardants.

[0046] This dispersion is obtained by mixing F particles, this dispersant polymer, a polar dispersion medium, and, if necessary, other nonionic surfactants, inorganic particles, other resins, additives, etc. This dispersion may be obtained by mixing the F particles, this dispersant polymer, and the polar dispersion medium all at once, or by mixing them in multiple stages. Furthermore, there are no particular limitations on the mixing order when further mixing the aforementioned other nonionic surfactants, inorganic particles, other resins, additives, etc., as needed. For example, they may be mixed with the F particles beforehand, added to the polar dispersion medium beforehand and then mixed with the F particles and this dispersant polymer, or mixed during the mixing of the F particles, this dispersant polymer, and the polar dispersion medium. 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.

[0047] The viscosity of this dispersion is preferably 10 mPa·s or higher, and more preferably 50 mPa·s or higher. The viscosity of this dispersion is preferably 3000 mPa·s or lower, and more preferably 1000 mPa·s or lower. In this case, the dispersion has excellent dispersibility and liquid properties, is easy to handle, has excellent coating properties and homogeneity, and easily forms a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc., based on the F polymer. Furthermore, in a dispersion with a viscosity within this range, the physical properties of the F polymer tend to be highly expressed in the polymer layer formed therefrom. The thixotropy ratio of this dispersion is 2.0 or less, preferably 1.0 to 1.4. In this case, the dispersion has excellent dispersibility and liquid properties, is easy to handle, has excellent coating properties and homogeneity, and readily forms a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc., based on the F polymer.

[0048] The present invention also relates to a method for producing a polymer-coated substrate (hereinafter also referred to as "this method"), which involves coating the surface of a substrate with the dispersion to form a coating layer made of the dispersion on the surface of the substrate, and then heating the substrate having the coating layer to form a polymer layer containing the tetrafluoroethylene polymer on the surface of the substrate. In this method, the method for applying the dispersion to the surface of the substrate can be any method that forms a stable liquid film (wet film) consisting of the dispersion on the surface of the substrate, and examples include coating, droplet dispensing, and immersion, with roll coating, knife coating, bar coating, die coating, or spraying being preferred.

[0049] The substrate is preferably a heat-resistant substrate. Examples of heat-resistant substrates include metal substrates such as metal foils of copper, nickel, aluminum, titanium, and their alloys; heat-resistant resin films such as polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide-imide, liquid crystalline polymers such as liquid crystalline polyester, and tetrafluoroethylene-based polymers other than F polymers such as polytetrafluoroethylene; ceramic substrates such as prepreg substrates (precursors of fiber-reinforced resin substrates), silicon carbide, aluminum nitride, and silicon nitride; and glass substrates. In particular, the heat-resistant substrate is preferably a film of a heat-resistant resin, such as polyimide, a liquid crystalline polymer, or polytetrafluoroethylene, with polyimide film being more preferable.

[0050] The substrate can be planar, curved, or uneven. Furthermore, the substrate may be foil-like, plate-like, film-like, or fibrous. In this method, the substrate may be a long substrate. In this case, a roll-to-roll process can be applied, and the polymer-coated substrate of the present invention, as described later, can be manufactured in a long form as a roll-shaped product, which is preferable from the viewpoint of improving productivity. The surface roughness of the substrate with a ten-point average is preferably 0.01 to 0.05 μm. The surface of the substrate may be surface-treated with a silane coupling agent or plasma-treated.

[0051] Next, the substrate having the coating layer is heated to remove the polar dispersion medium and melt and bake the F polymer, forming a polymer layer containing the F polymer on the surface of the substrate. When drying the coating layer to remove the polar dispersion medium, the coating layer is heated to a temperature at which the polar dispersion medium volatilizes, forming a dry film on the surface of the substrate. The heating for removing the polar dispersion medium is preferably performed at a temperature above the boiling point of the polar dispersion medium, for example, 80-200°C. During this heating, a dry film is formed by the packing of F particles. During heating, air may be blown onto the coating layer to promote the removal of the polar dispersion medium by air drying. During drying, the polar dispersion medium does not necessarily need to be completely evaporated; it only needs to be evaporated to the extent that the layer shape after retention is stable and the self-supporting film can be maintained. The dried film is further heated to a temperature above the melting point of the F polymer to form a polymer layer containing molten F particles (hereinafter also referred to as the "F layer") on the surface of the substrate, thereby producing a substrate with a polymer layer. In other words, a laminate having the F layer and the substrate layer in this order is obtained. Such heating is preferably carried out at 340 to 400°C.

[0052] The heating methods described above include using an oven, using a forced-air drying oven, and irradiating with heat rays such as infrared rays. The heat source in the apparatus may be a contact-type heat source (hot air, hot plate, etc.) or a non-contact heat source (infrared rays, etc.). Heating may be carried out under normal pressure (atmospheric pressure) or under reduced pressure. The atmosphere during heating may be either air or an inert gas atmosphere (helium, neon, argon, nitrogen, etc.). The heating time is preferably 0.1 minutes to 30 minutes, and more preferably 0.5 minutes to 20 minutes.

[0053] In this method, the F layer is formed by the steps of coating the substrate with the dispersion and heating. These steps may be performed once or repeated two or more times. For example, the dispersion may be coated onto the surface of the substrate to obtain a coating layer, the F layer may be formed by heating, the dispersion may be coated onto the surface of the F layer to obtain another coating layer, and the F layer may be formed by heating. Alternatively, the dispersion may be coated onto the surface of the substrate to obtain a coating layer, the polar dispersion medium may be removed by heating, the dispersion may be coated onto the surface again, and the F layer may be formed by the heating described above.

[0054] This dispersion may be placed on only one surface of the substrate, or on both surfaces of the substrate. In the former case, a substrate and a polymer-coated substrate having an F layer on one surface of the substrate are obtained. In the latter case, a substrate and a polymer-coated substrate having an F layer on both surfaces of the substrate are obtained. By separating the substrate from such a polymer-coated substrate, a film or sheet containing F polymer, which is a melt-fired body of F particles, can be obtained.

[0055] Suitable examples of polymer-coated substrates include a metal foil and a metal-clad laminate having an F layer on at least one surface of the metal foil, a polyimide film and a multilayer film having an F layer on both surfaces of the polyimide film.

[0056] The thickness of the F layer may be 1 μm or more, 5 μm or more, 10 μm or more, or 25 μm or more. The thickness of the F layer may be 1000 μm or less, 200 μm or less, 50 μm or less, 10 μm or less, or 5 μm or less. The dielectric constant of the F layer is preferably 2.4 or less, more preferably 2.0 or less. Furthermore, it is preferable that the dielectric constant be greater than 1.0. The dielectric loss tangent of the F layer is preferably 0.0022 or less, more preferably 0.0020 or less. Furthermore, it is preferable that the dielectric loss tangent be greater than 0.0010. The thermal conductivity of the F layer is preferably 1 W / m·K or more, more preferably 3 W / m·K or more. Note that the thermal conductivity of the F layer refers to the thermal conductivity in the in-plane direction of the F layer.

[0057] 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 substrate is preferably 10 N / cm or more, and more preferably 15 N / cm or more. The above peel strength is preferably 100 N / cm or less.

[0058] The present invention also relates to a polymer-coated substrate having a polymer layer (F layer) containing F polymer, formed from this dispersion. In such a polymer-layered substrate, the substrate is preferably a heat-resistant substrate, and the heat-resistant substrate is more preferably a metal foil or a heat-resistant resin film. Details of the heat-resistant substrate, metal foil, or heat-resistant resin film are as described above in the description of this method. Furthermore, such a polymer-coated substrate may have the F layer on one surface of the substrate, or it may have the F layer on both surfaces of the substrate. The preferred ranges for the thickness of the F layer, dielectric constant, dielectric loss tangent, thermal conductivity, coefficient of linear expansion, and peel strength between the polymer layer and the substrate layer in such a polymer-coated substrate are the same as the preferred ranges for the thickness of the F layer, dielectric constant, dielectric loss tangent, thermal conductivity, coefficient of linear expansion, and peel strength between the F layer and the substrate in the polymer-coated substrate formed from the dispersion described above.

[0059] The polymer-coated substrate formed from this dispersion is 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, flat wires, FFC (Flexible flat cable), etc.), enameled wire insulation materials used in motors for electric vehicles, etc., insulation materials for power generation, electrical insulation tapes, insulating tapes for oil drilling, oil transport hoses, hydrogen tanks, 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.), carrier films for fuel cells, tape substrate films for semiconductor manufacturing processes (dicing tapes, pickup tapes, etc.), release films for semiconductor molding, liquid crystal antennas, reflectors, transmission lines, COF (Chip On) Base films for film, electrostatic chucks for semiconductor manufacturing processes, electrostatic chucks for display manufacturing processes, copy rolls, furniture, car dashboards, covers for home appliances, sliding components (load bearings, yaw bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings, pistons, slide switches, gears, cams, belt conveyors, food transport belts, etc.), tension ropes, wear pads, wear strips, tube lamps, test sockets, wafer guides, wear parts for centrifugal pumps, chemical and water supply pumps, tools (shovels, files, drills, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, dies, toilets, container coverings, mounting heat dissipation substrates for power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, 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 polymer-coated substrate formed from this dispersion is particularly useful as an electronic circuit board material such as flexible printed circuit boards and rigid printed circuit boards, as well as as a protective film and a heat dissipation substrate, especially for automotive applications. [Examples]

[0060] 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 a tetrafluoroethylene polymer (F polymer 1, melting point: 300℃) with 1000 molecules per particle (D50: 2.0 μm, specific surface area: 7 m²) 2 / g) [Dispersant] Dispersant 1: A dispersant that is a diblock copolymer, manufactured according to Synthesis Example 2 of Japanese Patent Publication No. 2021-183314. Mn=9300, Mw / Mn=1.21, n 2 / n 1 =1.00 Dispersant 1 is a (meth)acrylate-based silicone polymer containing unit [I] and unit [II]. The A in unit [I] is such that Z in formula (1) is a propylene group, and R 3 It is a methyl group, m is 8, and there are three R 3a It is a group having a linear organopolysiloxane structure in which two of the groups are methyl groups and one is a n-butyl group. The B in unit [II] is such that n in formula (2) is 4, and R 4 It is a polyoxyalkylene group containing a methyl group. Dispersant 2: A dispersant that is a diblock copolymer, manufactured according to Example 10 of Japanese Patent Application Publication No. 2019-137775. Dispersant 2 is a copolymer in which the unit [II] in dispersant 1 is replaced with an acrylamide-based unit. [Polar dispersion medium] NMP: N-methylpyrrolidone

[0061] 2. Examples of dispersion preparation [Example 1] F particles 1, dispersant 1, and NMP were placed in a pot, and zirconia balls were added. The pot was then rotated at 150 rpm for 1 hour to obtain dispersion 1 containing F particles 1 (40 parts by mass), dispersant 1 (4 parts by mass), and NMP (56 parts by mass). The thixotropy ratio of dispersion 1 immediately after preparation was measured to be 1.1, and the thixotropy ratio remained stable even after continued shearing. Furthermore, the dispersion stability of dispersion 1 after being left at 20°C for 1 month was also good. [Example 2] Dispersion 2 was obtained in the same manner as in Example 1, except that dispersant 2 was used instead of dispersant 1, and contained F particles 1 (40 parts by mass), dispersant 2 (4 parts by mass), and NMP (56 parts by mass). The thixotropy of dispersion 2 immediately after preparation was measured to be 2.3, and it showed a tendency to increase in viscosity as shearing treatment was continued.

[0062] 3. Examples of manufacturing polymer-coated substrates and evaluation of the polymer layer Polymer-coated substrates were manufactured using dispersions 1 and 2, respectively, and the formed polymer layers were evaluated. Specifically, a coating layer was formed on one side of a copper foil (substrate 1: thickness 18 μm) by a roll-to-roll process using a small-diameter gravure reverse method. The copper foil having this coating layer was heated by passing it through a ventilated drying oven at a furnace temperature of 150°C for 5 minutes, and then passed through a far-infrared oven at a furnace temperature of 350°C for 5 minutes to melt and sinter the F particles, thereby obtaining polymer-clad substrates 1 and 2, each having a polymer layer (thickness 50 μm) containing the molten and sintered F particles on one side of substrate 1. Electrolytic copper foil (Fukuda Metal Foil & Powder Industry Co., Ltd., "CF-T49A-DS-HD2", thickness: 12 μm) was placed on the surface of the polymer layer of the obtained polymer-clad substrates 1 and 2, and pressed under vacuum at 340°C for 20 minutes to obtain copper-clad laminates 1 and 2. Comparing the obtained copper-clad laminate 1 and copper-clad laminate 2, copper-clad laminate 1 not only had higher interlayer adhesion and surface smoothness of the polymer layer, but also superior electrical properties (relative permittivity, dielectric loss tangent). [Industrial applicability]

[0063] The dispersion of the present invention has excellent dispersibility and liquid properties, is easy to handle, and can form a polymer layer with excellent mechanical properties, heat resistance, electrical properties, adhesion, etc. A polymer-coated substrate (laminated) having this polymer layer exhibits the properties of the F polymer to a high degree, and the polymer layer also has excellent interlayer adhesion with the substrate and metal foil, making it effective for use in applications such as printed circuit boards.

Claims

1. It comprises tetrafluoroethylene polymer particles, a dispersant, and a polar dispersion medium. A dispersion in which the dispersant is a (meth)acrylate-based silicone polymer containing the following units [I] and [II], and has a thixotropic ratio of 2.0 or less. 【Chemistry 1】 (In formula [I], R １ R represents a hydrogen atom or a methyl group, and A represents an organopolysiloxane-containing group. In formula [II], R ２ (where B represents a hydrogen atom or a methyl group, and B represents a polyoxyalkylene group-containing group.)

2. The dispersion according to claim 1, wherein the tetrafluoroethylene polymer comprises a heat-meltable tetrafluoroethylene polymer having a carbonyl group-containing group.

3. The dispersion according to claim 1, wherein the content of the tetrafluoroethylene polymer particles is 20% by mass or more.

4. The dispersion according to claim 1, wherein the average particle size of the tetrafluoroethylene polymer particles is 0.1 μm or more and 10 μm or less.

5. The dispersion according to claim 1, wherein the organopolysiloxane-containing group represented by A in the unit [I] is a group having a linear organopolysiloxane structure represented by the following formula (1). 【Chemistry 2】 (In formula (1), m represents 0 to 100, Z represents an alkylene group, and R ３ is an alkyl group or a phenyl group, R ３ａ (This represents an alkyl group, alkoxy group, or phenyl group.)

6. The dispersion according to claim 1, wherein the polyoxyalkylene group-containing group represented by B in the unit [II] is a group having an oxyethylene unit, represented by the following formula (2). -O(CH ２ CH ２ O)n-R ４ (2) (In the formula, n represents 1 to 100, R ４ (This represents an alkyl group or a hydrogen atom.)

7. The dispersion according to claim 1, wherein the dispersant is a (meth)acrylate-based silicone diblock polymer having polymer blocks composed of unit [I] and polymer blocks composed of unit [II].

8. The dispersion according to claim 7, wherein the terminal structure of the polymer block composed of the unit [I] is represented by the following formula [III], and the terminal structure of the polymer block composed of the unit [II] is represented by the following formula [IV], and the dispersion is a (meth)acrylate-based silicone diblock polymer. 【Transformation 3】 (In formula [III], R ５ represents an alkyl group, and R ６ represents a hydrogen atom or an alkyl group. In formula [IV], R ７ represents a hydrogen atom or a methyl group, and X represents a polyoxyalkylene group-containing group.)

9. The number of repeating units n of the unit [I] in the (meth)acrylate-based silicone polymer. １ Number of repeating units n with the aforementioned unit [II] ２ The ratio (n ２ / n １ The dispersion according to claim 1, wherein the ratio is 0.02 to 10.

10. The dispersion according to claim 1, wherein the (meth)acrylate-based silicone polymer has a number-average molecular weight (Mn) of 2,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.00 to 3.

00.

11. The dispersion according to claim 1, wherein the polar dispersion medium is one or more non-aqueous polar solvents selected from the group consisting of amides, ketones, and esters.

12. The dispersion according to claim 1, wherein the content of the dispersant relative to the particles of the tetrafluoroethylene polymer is 10% by mass or less.

13. The dispersion according to claim 1, wherein the viscosity is 1000 mPa or less.

14. A method for producing a polymer-coated substrate, comprising: coating the surface of a substrate with the dispersion liquid described in any one of claims 1 to 13 to form a coating layer made of the dispersion liquid on the surface of the substrate; and heating the substrate having the coating layer to form a polymer layer containing the tetrafluoroethylene polymer on the surface of the substrate.

15. A polymer-coated substrate having a polymer layer containing the tetrafluoroethylene polymer, formed from the dispersion liquid according to any one of claims 1 to 13.

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