Fluororesin composition

Abstract

To provide a fluororesin composition which exhibits excellent physical properties of a tetrafluoroethylene-based polymer, has excellent mechanical characteristics, heat resistance, electric characteristics and surface properties, especially excellent adhesiveness due to denseness, and which is capable of forming a polymer layer (film) having a small dimensional change rate.SOLUTION: Provided is a composition which contains two thermofusible tetrafluoroethylene-based polymers with an absolute value of melt flow rate (MFR) differences of 10 or more, in which one of the thermofusible tetrafluoroethylene-based polymers has an oxygen-containing polar group, MFR of the one thermofusible tetrafluoroethylene-based polymer is larger than MFR of the other thermofusible tetrafluoroethylene-based polymer, and a content of the other thermofusible tetrafluoroethylene-based polymer is larger than a content of the one thermofusible tetrafluoroethylene-based polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fluororesin composition. More specifically, the present invention relates to a fluororesin composition containing two or more melt processible fluororesins. [Background technology]

[0002] Tetrafluoroethylene-based polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as electrical properties, water and oil repellency, chemical resistance, and heat resistance, and are used in a variety of applications. In recent years, to accommodate the increasing speed and frequency of mobile communication devices such as mobile phones, materials with high thermal conductivity, low linear expansion coefficient, low dielectric constant, and low dielectric loss tangent are required for printed circuit boards of communication devices, and tetrafluoroethylene-based polymers with low dielectric constant and low dielectric loss tangent have attracted attention. Patent Document 1 proposes a composition comprising two or more melt processible fluororesins whose melt flow rates (MFR) satisfy a predetermined relationship. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-210420 Summary of the Invention [Problem to be solved by the invention]

[0004] The fluororesin composition disclosed in Patent Document 1 is said to have excellent melt flowability during injection molding and moldability. However, functional materials such as printed circuit board materials are required to have additional physical properties such as adhesion between conductive and insulating layers in addition to heat resistance, durability, and mechanical properties. Therefore, it is necessary to consider the affinity and uniform dispersibility of the components that make up the fluororesin composition. The present inventors have found that a composition containing two specific types of heat-meltable tetrafluoroethylene-based polymers having different MFRs in a predetermined ratio can form a molded product that is excellent in mechanical properties, heat resistance, electrical properties (low linear expansion coefficient, low dielectric constant, low dielectric dissipation factor, etc.), surface properties, and adhesion, and can form a polymer layer (film) that is particularly dense and has excellent adhesion and a small rate of dimensional change, thereby completing the present invention. An object of the present invention is to provide a fluororesin composition that can be used to form a polymer layer (film) that has high levels of the physical properties of a tetrafluoroethylene-based polymer, is excellent in mechanical properties, heat resistance, electrical properties, and surface properties, and is particularly dense and has excellent adhesive properties and a small rate of dimensional change. Another object of the present invention is to provide such a polymer layer (film). [Means for solving the problem]

[0005] The present invention has the following aspects. [1] A composition containing two types of heat-meltable tetrafluoroethylene-based polymers whose difference in melt flow rate (MFR) has an absolute value of 10 or more, one of the heat-meltable tetrafluoroethylene-based polymers having an oxygen-containing polar group, the MFR of one of the heat-meltable tetrafluoroethylene-based polymers being higher than the MFR of the other heat-meltable tetrafluoroethylene-based polymer, and the content of the other heat-meltable tetrafluoroethylene-based polymer being higher than the content of one of the heat-meltable tetrafluoroethylene-based polymers. [2] The composition according to [1], which contains the two types of heat-fusible tetrafluoroethylene polymers as particles. [3] The one of the heat-meltable tetrafluoroethylene-based polymers has an MFR of 15 g / 10 min or more, and the number of the oxygen-containing polar groups is 10 or less. 6 The composition of [1] or [2], wherein the number of particles per particle is 200 or more. [4] The other heat-meltable tetrafluoroethylene-based polymer has an MFR of less than 15 g / 10 min, and the number of oxygen-containing polar groups is 10 or less. 6 The composition of any one of [1] to [3], wherein the number of particles per particle is less than 200. [5] The composition according to any one of [1] to [4], wherein the absolute value of the difference between the MFR of one of the heat-meltable tetrafluoroethylene polymers and the MFR of the other of the heat-meltable tetrafluoroethylene polymers is 50 or less. [6] The composition according to any one of [1] to [5], wherein the melting point of the one hot-melt tetrafluoroethylene-based polymer and the melting point of the other hot-melt tetrafluoroethylene-based polymer are each 200°C or higher and 320°C or lower, and the absolute value of the difference between the melting points is within 25°C. [7] The composition according to [6], wherein the melting point of the one heat-meltable tetrafluoroethylene polymer is equal to or lower than the melting point of the other heat-meltable tetrafluoroethylene polymer. [8] The composition of any one of [1] to [7], wherein the content of the one heat-meltable tetrafluoroethylene-based polymer is 5% by mass or more and 25% by mass or less relative to the total content of the one heat-meltable tetrafluoroethylene-based polymer and the other heat-meltable tetrafluoroethylene-based polymer. [9] The composition of any one of [1] to [8], wherein the content of the fluorine-containing compound having a hydrophilic group is 250 ppb by mass or less based on the total content of the one heat-meltable tetrafluoroethylene-based polymer and the other heat-meltable tetrafluoroethylene-based polymer.

[10] The particles of the one of the heat-meltable tetrafluoroethylene polymers have an average particle size of 0.1 μm or more and 40 μm or less and a specific surface area of ​​6 m 2 / g or more 40m 2 The composition of any one of [2] to [9], wherein the particle size is 1 / g or less.

[11] The composition according to any one of [2] to

[10] , further comprising a liquid dispersion medium in which particles of the one heat-fusible tetrafluoroethylene-based polymer and particles of the other heat-fusible tetrafluoroethylene-based polymer are dispersed.

[12] The composition according to any one of [1] to

[10] , which is in the form of a powder or pellet.

[13] A method for producing a polymer layer, comprising placing the composition according to

[11] on the surface of a substrate and heating the composition to form a polymer layer containing the one heat-fusible tetrafluoroethylene-based polymer and the other heat-fusible tetrafluoroethylene-based polymer.

[14] A film formed by extruding the composition according to any one of [1] to

[12] or by disposing it on the surface of a substrate.

[15] A film according to

[14] , in which the absolute value of the dimensional change rate in MD and TD before and after heat treatment is within 2% when measured after heat treatment for 10 minutes at 180°C and then cooled to 25°C, and the oxygen element ratio is 0.1 atomic% or more when the surface condition of one or both sides is measured by a scanning X-ray photoelectron spectroscopy analyzer (XPS / ESCA) after heat treatment for 3 minutes at 180°C. [Effects of the Invention]

[0006] According to the present invention, there is provided a composition which can be used to form molded articles such as polymer layers (films) which have high physical properties of tetrafluoroethylene-based polymers and are excellent in mechanical properties, heat resistance, electrical properties, surface properties, etc., and which are particularly dense and have excellent adhesive properties and a small rate of dimensional change. DETAILED DESCRIPTION OF THE INVENTION

[0007] The following terms have the following meanings: The "melt flow rate (MFR) of a heat-meltable tetrafluoroethylene polymer" is a value measured at 372°C under a load of 5 kg in accordance with ASTM D3307. The "melting point of a polymer" is the temperature corresponding to the maximum value of the melting peak of the polymer as measured by differential scanning calorimetry (DSC). The "glass transition temperature (Tg)" is a value measured by analyzing a polymer using the dynamic mechanical analysis (DMA) method. "Average particle size (D50)" is the volume-based cumulative 50% diameter of particles determined by laser diffraction / scattering. In other words, particle size distribution is measured by laser diffraction / scattering, and a cumulative curve is calculated with the total volume of the particle group as 100%. The average particle size (D50) is the particle size at the point on the cumulative curve where the cumulative volume is 50%. The D50 of particles is determined by dispersing the particles in water and analyzing them by the laser diffraction / scattering method using a laser diffraction / scattering particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.). The specific surface area of ​​the particles is a value calculated by measuring the particles by the gas adsorption (constant volume method) BET multipoint method, and is determined using NOVA4200e (manufactured by Quantachrome Instruments). The "viscosity" is determined by measuring the composition using an E-type viscometer at 25°C and a shear rate of 10 / sec. The measurement is repeated three times, and the average value of the three measurements is used. The "thixotropy ratio" is a value calculated by dividing the viscosity η1 of a composition measured at a shear rate of 10 / sec by the viscosity η2 measured at a shear rate of 100 / sec. The term "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of the monomer. The unit may be a unit formed directly by a polymerization reaction, or may be a unit in which a portion of the unit is converted into a different structure by processing the polymer. Hereinafter, a unit based on monomer a will also be referred to simply as a "monomer a unit."

[0008] The present invention relates to a composition (hereinafter also referred to as "the composition") containing two types of heat-meltable tetrafluoroethylene-based polymers (hereinafter also referred to as "F polymers") whose absolute value of the difference in melt flow rates (MFR) is 10 or more, one of the heat-meltable tetrafluoroethylene-based polymers (hereinafter also referred to as "one of the F polymers") has an oxygen-containing polar group, the MFR of one of the F polymers is higher than the MFR of the other heat-meltable tetrafluoroethylene-based polymer (hereinafter also referred to as "the other F polymer"), and the content of the other F polymer is higher than the content of the one of the F polymers.

[0009] This composition allows the formation of molded articles such as polymer layers (films) that exhibit excellent mechanical properties, heat resistance, electrical properties, surface properties, etc., and have small dimensional change and excellent adhesiveness, due to the highly expressed physical properties of the F polymer. The reasons for this are not entirely clear, but are thought to be as follows. One of the F polymers in this composition not only has relatively higher thermal fluidity than the other F polymer, but also has a relatively higher surface tension due to the presence of oxygen-containing polar groups. Therefore, when this composition is heated to melt and sinter the F polymer to form a molded product, it is presumed that one of the F polymers not only fills the spaces between the other F polymers and functions as a binder, but also migrates to the surface of the molded product and becomes unevenly distributed. As a result, it is presumed that the adhesive properties of one of the F polymers, based on the oxygen-containing polar groups, are highly imparted to the molded product. Furthermore, this mechanism of action is presumed to result in the formation of a dense molded product of the F polymer, which not only maintains the physical properties of the F polymer, such as mechanical properties, heat resistance, and electrical properties, but also produces a molded product with a small dimensional change rate. This tendency is likely to be significant when the composition contains two types of F polymers as particles, the melting points of one F polymer and the other F polymer are 200°C or higher and 320°C or lower, the absolute value of the difference between the melting points is within 25°C, and the melting point of one F polymer is lower than the melting point of the other F polymer.

[0010] The F polymer in the present invention is a heat-fusible polymer containing units (hereinafter also referred to as "TFE units") based on tetrafluoroethylene (hereinafter also referred to as "TFE"). Here, the heat-fusible polymer means a polymer that has a temperature at which the melt flow rate is 1 to 1000 g / 10 min under a load of 49 N. The melting point of the F polymer is preferably above 100° C., more preferably 180° C. or higher, and even more preferably 200° C. or higher. The melting point of the F polymer is preferably 325° C. or lower, more preferably 320° C. or lower. In this case, the composition tends to have excellent processability, and molded products such as polymer layers (films) formed from the composition tend to have excellent heat resistance.

[0011] The glass transition point of the F polymer is preferably 50° C. or higher, more preferably 75° C. or higher. The glass transition point of the F polymer is preferably 150° C. or lower, more preferably 125° C. or lower. The fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass. The surface tension of the F polymer is preferably 16 to 26 mN / m. The surface tension of the F polymer can be measured by placing a droplet of a mixture for wetting tension testing (manufactured by Wako Pure Chemical Industries, Ltd.) specified in JIS K 6768 on a flat plate made of the F polymer.

[0012] Examples of F polymers include polytetrafluoroethylene (PTFE), polymers containing TFE units and units based on ethylene (ETFE), polymers containing TFE units and units based on propylene, polymers containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units) (PFA), polymers containing TFE units and units based on hexafluoropropylene (HFP) (FEP), TFE / ethylene / HFP copolymers, polymers containing ethylene units and units based on chlorotrifluoroethylene (CTFE) (ECTFE), polychlorotrifluoroethylene (PCTFE), polymers containing CTFE units and TFE units, polyvinylidene fluoride (PVdF), polymers containing TFE units and units based on vinylidene fluoride (VdF) (VT), polyvinyl fluoride (PVF), polymers containing TFE units, VdF units, and CTFE units (VTC), and polymers containing TFE units, HFP units, and VdF units. Among these, polytetrafluoroethylene (PTFE), polymers containing TFE units and units based on ethylene (ETFE), polymers containing TFE units and units based on propylene, polymers containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units) (PFA), and polymers containing TFE units and units based on hexafluoropropylene (FEP) are preferred, 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, or CF2=CFOCF2CF2CF3 (hereinafter also referred to as "PPVE"), and PPVE is more preferred.

[0013] One of the F polymers in the composition has an oxygen-containing polar group. The oxygen-containing polar group of the other F polymer preferably has a hydroxyl group-containing group or a carbonyl group-containing group, more preferably a carbonyl group-containing group. In this case, in the composition further containing a liquid dispersion medium, as described below, the two types of F polymers, each preferably in the form of particles, tend to have excellent dispersibility. Furthermore, the composition can easily be used to obtain a molded product, such as a polymer layer (film), that has excellent mechanical properties, heat resistance, electrical properties, surface properties, and adhesive properties, and is particularly dense and adhesive, with a small dimensional change rate. The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF2CH2OH and -C(CF3)2OH. The carbonyl group-containing group is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), a formyl group, a halogenoformyl group, a urethane group (-NHC(O)O-), a carbamoyl group (-C(O)-NH), a ureido group (-NH-C(O)-NH), an oxamoyl group (-NH-C(O)-C(O)-NH), or a carbonate group (-OC(O)O-), and more preferably an acid anhydride residue. On the other hand, the number of oxygen-containing polar groups in the F polymer is 1 × 10 6 The number of oxygen-containing polar groups in one of the F polymers is preferably 100 or more, more preferably 200 or more, per carbon atom. 6 Preferably, the number is 3000 or less, more preferably 1200 or less per unit. The number of oxygen-containing polar groups in one F polymer can be quantified by the composition of the polymer or the method described in WO 2020 / 145133.

[0014] The oxygen-containing polar group may be contained in a unit based on a monomer in one of the F polymers, or may be contained in a terminal group of the main chain of the F polymer. 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 subjecting an F polymer to plasma treatment or ionizing radiation treatment. The monomer having a carbonyl group-containing group is preferably itaconic anhydride, citraconic anhydride, or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"), and more preferably NAH.

[0015] On the other hand, the F polymer is preferably a polymer having a carbonyl group-containing group containing TFE units and PAVE units, more preferably a polymer containing TFE units, PAVE units, and units based on a monomer having a carbonyl group-containing group, and more preferably a polymer containing these units in the following order, based on the total units: 90 to 99 mol%, 0.99 to 9.97 mol%, and 0.01 to 3 mol%. Specific examples of such F polymers include the polymers described in WO 2018 / 16644.

[0016] In this composition, the absolute value of the difference in MFR between one F polymer and the other F polymer is 10 or more, and the MFR of one F polymer is greater than the MFR of the other F polymer. When the MFRs of one F polymer and the other F polymer satisfy the above-mentioned relationship, a molded product such as a polymer layer (film) formed from this composition highly exhibits the physical properties of the F polymer, has a small dimensional change rate, and is excellent in surface properties and adhesiveness. The MFR of one of the F polymers is preferably 15 g / 10 min or more, more preferably 20 g / 10 min or more. The MFR of one of the F polymers is preferably 100 g / 10 min or less, more preferably 50 g / 10 min or less. In particular, in the present composition, the MFR of one of the F polymers is 15 g / 10 min or more, and the number of the oxygen-containing polar groups is 10 or less. 6Preferably, the number of oxygen-containing polar groups per unit area is 200 or more. When the F polymer has a predetermined amount or more of oxygen-containing polar groups, a molded product such as a polymer layer (film) formed from the composition exhibits the physical properties of the F polymer to a high degree, has a small dimensional change rate, and is excellent in surface properties and adhesiveness.

[0017] The MFR of the other F polymer is preferably less than 15 g / 10 min. The MFR of the other F polymer is preferably 1 g / 10 min or more. The number of oxygen-containing polar groups in the other F polymer is preferably 1 x 10 carbon atoms in the main chain. 6 The number of oxygen-containing polar groups in the other F polymer is preferably less than 200, more preferably 50 or less, per unit area. 6 In particular, in the present composition, it is preferable that the MFR of the other F polymer is less than 15 g / 10 min and the number of the oxygen-containing polar groups is 10 or more. 6 Preferably there are less than 200 per cell. The absolute value of the difference between the MFR of one F polymer and the MFR of the other F polymer is preferably 50 or less, more preferably 30 or less, from the viewpoint of facilitating processability of the present composition.

[0018] In the present composition, it is also preferred that the melting point of one F polymer and the melting point of the other F polymer are each 200° C. or higher and 320° C. or lower, and that the absolute value of the difference between the melting points is within 25° C. Furthermore, it is more preferred that the melting point of one F polymer is lower than the melting point of the other F polymer, from the viewpoints of improving the processability of the present composition and further improving the surface properties and adhesiveness of molded products such as polymer layers (films) obtained from the present composition. In the present composition, the content of one F polymer relative to the total content of one F polymer and the content of the other F polymer is preferably from 1% by mass to less than 50% by mass, and more preferably from 5% by mass to 25% by mass, from the viewpoint that the two types of F polymers, each preferably in the form of particles, tend to have excellent dispersibility in the present composition further containing a liquid dispersion medium, as described below, and from the viewpoint that the surface properties and adhesiveness of a molded product such as a polymer layer (film) obtained from the present composition are more likely to be improved.

[0019] The present composition may contain a fluorine-containing compound having a hydrophilic group.However, the content of the fluorine-containing compound having a hydrophilic group is preferably 250 mass ppb or less, more preferably 100 mass ppb or less, and more preferably below the detection limit (5 mass ppb), in other words, more preferably not contained.Specific examples of such hydrophilic fluorine-containing compounds include perfluorocarboxylic acids or their salts such as perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid and perfluorotetradecanoic acid. The content of the fluorine-containing compound having a hydrophilic group in the present composition can be measured, for example, by the liquid chromatography tandem mass spectrometry method specified in CEN / TS15968.

[0020] The present composition, in which the content of the fluorine-containing compound having a hydrophilic group satisfies the above-mentioned range, is easy to handle and easy to mold. Specifically, it can prevent contamination of the molding device during molding of the present composition and prevent the fluorine-containing compound having a hydrophilic group from bleeding out onto the surface of the resulting molded article, such as a polymer layer (film), which can cause surface contamination. Furthermore, when the present composition, which is in a liquid state, is prepared and used, or when added to other resin varnishes, it can prevent corrosiveness. Molded articles such as polymer layers and films obtained using the present composition fully exhibit the excellent properties of the two F polymers. Furthermore, as will be described later, the present composition, which is in powder form, can be used in powder coating to easily form a coating film with excellent surface uniformity.

[0021] In the present composition, an example of a means for adjusting the content of the fluorine-containing compound having a hydrophilic group within the above-mentioned range is to add a radical generator selected from organic peroxides, inorganic peroxides, organic azo compounds, and combinations of oxidizing agents and reducing agents to a mixed liquid obtained by separating unreacted monomers after the polymerization reaction during the production of one F polymer and the other F polymer, and then heat-treat the mixture preferably at a temperature in the range of 35°C to 120°C. Alternatively, one F polymer and the other F polymer may be washed in advance, or may be subjected to a treatment in advance to cause them to flow in a predetermined temperature range under a reduced pressure atmosphere, for example. Alternatively, after preparing the present composition containing one F polymer and the other F polymer, the composition may be washed or may be subjected to a treatment in advance to cause them to flow in a predetermined temperature range under a reduced pressure atmosphere, for example.

[0022] The composition may further contain high-molecular-weight polytetrafluoroethylene (high-molecular-weight PTFE) in an amount of 0.01% by mass or more and 1% by mass or less, based on the total amount of the composition. The high-molecular-weight PTFE is preferably a non-thermofusible PTFE that does not exhibit melt fluidity even at or above its melting point and has a crystallization heat of fusion of less than 50 J / g. When the composition further contains high-molecular-weight PTFE in the above range, when the composition is used to form an injection-molded article, the entanglement of surface molecular chains is strengthened, further improving the surface uniformity of the molded article. Furthermore, the entanglement of the entire molecular chains of the injection-molded article is also strengthened, improving the strength and solvent resistance of the molded article.

[0023] The present composition also encompasses compositions in which the two types of F polymers are in the form of particles having a so-called core-shell structure, and compositions in which the two types of F polymers are combined at an even microscopic level compared to particles. However, from the viewpoint of the excellent dispersibility of the two types of F polymers in the present composition further containing a liquid dispersion medium, as will be described later, and the ease of forming a polymer layer (film) from the present composition that is excellent in mechanical properties, heat resistance, electrical properties, and surface properties, and is particularly dense and adhesive, and has a small dimensional change rate, it is preferable that the present composition contains the two types of F polymers as particles.

[0024] In this case, the average particle size (D50) of the particles of one of the F polymers is preferably 0.1 μm or more, more preferably 1 μm or more, and is preferably 40 μm or less, more preferably 20 μm or less. On the other hand, the specific surface area of ​​the F polymer particles is 6m 2 / g or more, and 2 / g or more is more preferable. 2 / g or less is preferable. In this composition, the particles of the one F polymer have an average particle size of 0.1 μm or more and 40 μm or less and a specific surface area of ​​6 m 2 / g or more 40m 2 / g or less, in which case the above-mentioned mechanism of action is more likely to be exhibited significantly.

[0025] The average particle size (D50) of the other F polymer particles is preferably 0.01 μm or more, more preferably 0.1 μm or more, and is preferably 10 μm or less, more preferably less than 1 μm. On the other hand, the specific surface area of ​​the F polymer particles is 10 m 2 / g or more, and 2 / g or more is more preferable. 2 In this case, the above-mentioned mechanism of action is more likely to be exhibited significantly.

[0026] In this composition, it is more preferable that the D50 of the particles of the other F polymer is smaller than the D50 of the particles of one F polymer, and it is even more preferable that the specific surface area of ​​the particles of the other F polymer is smaller than the specific surface area of ​​the particles of one F polymer. In this case, aggregation of the particles of the two types of F polymers is easily suppressed, and the composition is likely to have excellent dispersibility and processability. In addition, it is easy to form a polymer layer (film) from this composition that is excellent in mechanical properties, heat resistance, electrical properties, and surface properties, and is particularly dense and has excellent adhesive properties and a small dimensional change rate.

[0027] The high-molecular-weight PTFE particles may be mixed with particles of two types of F polymers. In this case, the aggregation-inhibiting effect of the two types of F polymer particles and the retention effect of the high-molecular-weight PTFE due to fibrillation are balanced, which tends to improve the dispersibility of the composition. Furthermore, the electrical properties of the high-molecular-weight PTFE are likely to be highly expressed in molded products such as polymer layers (films) obtained from the composition.

[0028] The composition may further contain a liquid dispersion medium. The liquid dispersion medium is preferably a compound that is liquid at 25°C under atmospheric pressure and has a boiling point of 50 to 240°C. One type of liquid dispersion medium may be used, or two or more types may be used. When two types of liquid dispersion medium are used, the two types of liquid dispersion medium are preferably compatible with each other. The liquid dispersion medium is preferably a compound selected from the group consisting of water, hydrocarbons, amides, ketones and esters. Examples of hydrocarbons include alicyclic hydrocarbons such as hexane, heptane, octane, decane, and methylcyclohexane, and aromatic hydrocarbons such as toluene, ethylbenzene, and xylene. 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 the ester 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 liquid dispersion media, water is preferred from the viewpoints of ease of handling and minimal impact on the environment.

[0029] Furthermore, in the present composition (hereinafter also referred to as "the present liquid composition") which contains a liquid dispersion medium, it is preferable that two types of F polymers are contained as particles, and that particles of one F polymer and particles of the other F polymer are dispersed. The details of the particles of one F polymer and particles of the other F polymer are the same as those described above, and it is presumed that in the present liquid composition, the particles of one F polymer improve the dispersion state of the particles of the other F polymer, and therefore the dispersion stability is excellent.

[0030] When the composition further contains a liquid dispersion medium, the content thereof is preferably 10% by volume or more, more preferably 20% by volume or more.When the composition further contains a liquid dispersion medium, the content thereof is preferably 60% by volume or less, more preferably 50% by volume or less. When the present composition further contains a liquid dispersion medium, the solid content concentration in the present liquid composition is preferably 50% by volume or more. The solid content concentration is preferably 90% by volume or less. The solid content refers to the total amount (total mass or total volume) of substances that form solid content in a molded product formed from the present liquid composition. Specifically, the F polymer is a solid content, and when the present liquid composition further contains other resins, inorganic fillers, etc., the other resins and inorganic fillers are also solid content, and the total volume concentration of these components is the solid content concentration in the present liquid composition. When the volume concentration is within this range, the liquid composition is likely to have excellent dispersibility. In addition, the liquid composition is likely to produce a molded product such as a polymer layer (film) that is excellent in mechanical properties, heat resistance, electrical properties, and surface properties, and is particularly dense and has excellent adhesive properties and a small dimensional change rate.

[0031] When the composition further contains a liquid dispersion medium, the viscosity of the liquid composition is preferably 100 mPa·s or more, more preferably 1000 mPa·s or more. The viscosity of the liquid composition is preferably 30,000 mPa·s or less, more preferably 10,000 mPa·s or less. In this case, the liquid composition has excellent coatability and is easy to form a layer of any desired thickness. Furthermore, when the liquid composition has a viscosity within this range, the physical properties of the F polymer are easily expressed in molded products such as polymer layers (films) formed from the liquid composition. When the present composition further contains a liquid dispersion medium, the thixotropy ratio of the present liquid composition is preferably 1.1 to 8.0, in which case the present liquid composition has excellent coatability and homogeneity, and is easily formed into a molded product such as a polymer layer (film).

[0032] The present composition may further contain other components to the extent that the effects of the present composition can be maintained, such as resins other than the F polymer and high-molecular-weight PTFE, inorganic fillers, surfactants, thixotropic agents, viscosity modifiers, antifoaming agents, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, mold release agents, and flame retardants.

[0033] The composition can be obtained by mixing two types of F polymers, each preferably in the form of particles, with a liquid dispersion medium and other components as needed. The liquid composition may be obtained by mixing two types of F polymers, each of which is preferably in the form of particles, with a liquid dispersion medium all at once, or they may be mixed sequentially, or a master batch of these may be prepared in advance and then mixed with the remaining components. There are no particular restrictions on the order of mixing, and the mixing method may be either all at once or in multiple batches. Other components that may be added as needed may be mixed with the two types of F polymers before mixing, may be added to the liquid dispersion medium before mixing with the two types of F polymers, or may be mixed when mixing the two types of F polymers with the liquid dispersion medium. Examples of mixing devices for obtaining the present composition include agitators equipped with blades, such as a Henschel mixer, pressure kneader, Banbury mixer, and planetary mixer; grinding devices equipped with media, such as a bead mill, ball mill, attritor, basket mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC mill, spike mill, and agitator mill; and dispersing devices equipped with other mechanisms, such as a microfluidizer, nanomizer, ultimizer, ultrasonic homogenizer, dissolver, disper, centrifugal stirrer, high-speed impeller, thin film swirling high-speed mixer, planetary mixer, and V-type mixer.

[0034] The composition may be in the form of a powder or pellets. The composition of this embodiment can be suitably used, for example, in powder coating applications, and can form a thin polymer layer with a uniform surface. When the composition is used in powder coating applications, the average particle size (D50) of the composition is preferably 10 μm or more and 50 μm or less. Examples of methods for applying powder coatings include spraying, electrostatic spraying, electrostatic spray coating, fluidized bed dip coating, electrostatic fluidized bed dip coating, roto-lining, etc. After the powder coating is applied to the substrate, it is heated and baked to form a coating film, and the thickness of the coating film is preferably 20 μm or more and 10,000 μm or less.

[0035] The composition can be melt-extruded into a film using, for example, an extruder equipped with a T-die. The melt-extrusion may be carried out immediately after melt-kneading the composition, or may be carried out while melt-kneading the composition in the extruder. The melt extrusion conditions are usually preferably set at a temperature 20° C. or more higher than the higher of the melting points of the two F polymers contained in the present composition. The thickness of the film formed from the composition is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the film formed from the composition is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 200 μm or less. The film thickness can be controlled by appropriately adjusting the T-die clearance, take-up speed, coating amount of the composition, etc. Films formed from the present compositions preferably have a dielectric constant of 2.4 or less, more preferably 2.0 or less, and preferably greater than 1.0. The dielectric loss tangent of a film formed from the composition is preferably 0.0022 or less, more preferably 0.0020 or less, and preferably greater than 0.0010. The linear expansion coefficient of a film formed from the composition is preferably 80 ppm / °C or less, more preferably 40 ppm / °C or less. The lower limit of the linear expansion coefficient of a film formed from the composition is 5 ppm / °C. The linear expansion coefficient refers to the value measured for a test piece in the temperature range of -40°C to 200°C according to the measurement method specified in JIS C 6471:1995. The thermal conductivity of a film formed from this composition is preferably 1 W / m K or more, and more preferably 3 W / m K or more. The upper limit of this thermal conductivity is 100 W / m K. The thermal conductivity of the film refers to the thermal conductivity in the in-plane direction of the film. The film formed from the composition may be a continuous film.

[0036] The liquid composition described above is also suitable for use as a composition for forming a polymer layer containing the F polymer by applying it to at least one surface of a substrate and heating it. For example, by placing this liquid composition on the surface of a substrate and heating it, a polymer layer containing one F polymer and the other F polymer (hereinafter also referred to as "F layer") can be formed, and the F layer can be obtained by peeling it off from the substrate or by dissolving or etching the substrate. This liquid composition has excellent liquid physical properties such as dispersion stability, and by the above-mentioned mechanism of action, it is possible to form a molded product based on the F polymer with excellent physical properties. That is, the present invention encompasses a method for producing a polymer layer (hereinafter also referred to as "the method") in which the present composition, which further contains a liquid dispersion medium, is placed on the surface of a substrate and heated to form a polymer layer containing one F polymer and the other F polymer. This method is suitable for forming a thin F layer of less than a few micrometers from this liquid composition, which highly exhibits the physical properties of the F polymer and has excellent mechanical properties, heat resistance, electrical properties, etc., a small dimensional change rate, and excellent adhesiveness.

[0037] The liquid composition is applied to the surface of a substrate to form a coating layer of the liquid composition on the surface of the substrate. The application method may be any method that forms a stable liquid film (wet film) of the liquid composition on the surface of the substrate, and examples of the application method include coating by a coating method, a droplet ejection method, and a dipping method, with roll coating, knife coating, bar coating, die coating, and spraying being preferred.

[0038] Examples of the substrate include metal substrates such as metal foils of copper, nickel, aluminum, titanium, alloys thereof, etc.; films of preferably heat-resistant resins such as tetrafluoroethylene-based polymers other than F polymers, such as polyester, polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyaryl ether ketone, polyamideimide, liquid crystalline polyester, and polytetrafluoroethylene; prepreg substrates (precursors of fiber-reinforced resin substrates), ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride; and glass substrates.

[0039] The shape of the substrate may be flat, curved, or uneven, and may be any of foil, plate, film, and fiber. In this method, the substrate may be a long substrate, which is preferable from the viewpoint of improving productivity, since a roll-to-roll process can be applied and the F layer can be produced in a long form as a roll-shaped product. The ten-point average roughness of the surface of the substrate is preferably 0.05 to 10.0 μm. The surface of the substrate may be surface-treated with a silane coupling agent.

[0040] Next, the substrate having the coating layer is heated to remove the liquid dispersion medium and melt and bake the F polymer, thereby obtaining a substrate having an F layer on its surface. When drying the coating layer, the coating layer is heated to a temperature at which the liquid dispersion medium volatilizes, forming a dry film on the surface of the substrate. Heating for removing the liquid dispersion medium is preferably performed at a temperature equal to or higher than the boiling point of the liquid dispersion medium, for example, 80 to 200°C. During this heating, a dry film is formed by packing of particles of one F polymer with particles of the other F polymer. During heating, air may be blown onto the surface to promote air drying and removal of the liquid dispersion medium. During drying, the liquid dispersion medium does not necessarily have to be completely evaporated, but it is sufficient to evaporate it to an extent that the layer shape after holding is stable and a free-standing film can be maintained. The dried coating is further heated to a temperature equal to or higher than the melting point of the F polymer to form an F layer containing a molten and sintered product of particles of two types of F polymer on the surface of the substrate. In other words, a laminate having an F layer and a substrate layer in this order is obtained. The heating is preferably carried out at 340 to 400°C. The above-mentioned heating methods include a method using an oven, a method using a ventilation drying furnace, and a method using heat rays such as infrared rays. The heat source in the device may be a contact type heat source (hot air, hot plate, etc.) or a non-contact type heat source (infrared rays, etc.). Heating may be performed under either atmospheric pressure or reduced pressure, and the heating atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). The heating time is preferably from 0.1 to 30 minutes, more preferably from 0.5 to 20 minutes. By heating under the above conditions, the F layer can be suitably formed while maintaining high productivity. The peel strength between the F layer and the substrate is preferably 10 N / cm or more, more preferably 15 N / cm or more, and is preferably 100 N / cm or less.

[0041] In this method, the F layer is formed through the steps of disposing of the liquid composition and heating. These steps may be performed once, or may be repeated two or more times. For example, the liquid composition may be disposed on the surface of a substrate and heated to form an F layer, and then the liquid composition may be disposed on the surface of the F layer and heated to form a second F layer. Alternatively, the liquid composition may be disposed on the surface of a substrate and heated to remove the liquid dispersion medium, and then the liquid composition may be disposed on the surface of the substrate and heated to form an F layer.

[0042] The present invention also relates to a film (hereinafter also referred to as "the present film") formed by extruding the above-described present composition or by disposing it on the surface of a substrate. Here, the present film also includes the above-described F layer formed by disposing the present composition further containing a liquid dispersion medium on the surface of a substrate. The details of the F polymer in the present film are the same as those described above in the description of the present composition. The preferred ranges of the dielectric constant, dielectric loss tangent, linear expansion coefficient, and thermal conductivity of the present film are the same as those described above.

[0043] The film is preferably such that the absolute value of the dimensional change rate in the MD and TD before and after heat treatment is within 2% when heat-treated for 10 minutes at 180°C and then cooled to 25°C, and the oxygen element ratio is 0.1 atomic% or more when the surface condition of one or both sides of the film is measured by a scanning X-ray photoelectron spectroscopy analyzer (XPS / ESCA) after heat treatment for 3 minutes at 180°C. The absolute value of the dimensional change rate of the present film before and after heat treatment is preferably 1.8% or less, more preferably less than 1.5%. The dimensional change rate is a value calculated from the change in the gauge spacing before and after heat treatment by measuring the gauge spacing in both the MD and TD directions on a test piece cut into a 300 mm square from the present film, marking it at 180 mm intervals on the test piece, heat-treating it in an air atmosphere at 180°C for 10 minutes without applying a load, and then cooling it to 25°C.

[0044] The oxygen atomic ratio of the present film after heat treatment is more preferably 0.2 atomic % or more, and even more preferably 0.5 atomic % or more. The upper limit of the oxygen atomic ratio may be less than 2 atomic %. Even in this case, the adhesion between the present film and a substrate such as a metal foil is likely to be improved due to the above-mentioned mechanism of action. The oxygen atomic ratio was determined by placing a test piece for XPS / ESCA measurement made from this film on a metal tray, heat-treating it in an air atmosphere in an electric furnace at 180°C for 3 minutes, and then measuring the surface condition of one or both sides of the test piece by XPS / ESCA.

[0045] The present film may be further laminated with other layers, such as heat-resistant resin films of liquid crystal polymers such as polyimide, polyamide, polyetheramide, polyphenylene sulfide, polyaryl ether ketone, polyamideimide, and liquid crystal polyester, and tetrafluoroethylene-based polymers other than F polymers such as polytetrafluoroethylene; prepreg substrates (precursors of fiber-reinforced resin substrates), ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride; and glass substrates.

[0046] A laminate can be formed by laminating the present film on a substrate. Examples of methods for producing a laminate include a method of thermocompression bonding the present film and a substrate. Furthermore, in the above-described method suitable for producing the present film, a laminate consisting of the present film and a substrate layer may be produced by using a co-extruder as the extruder to extrude the present composition together with the raw materials for the substrate, a method of extruding the present composition onto a substrate, or a method of coating a long substrate with the present composition or the present liquid composition to first form a coating layer consisting of the present composition or the present liquid composition on the surface of the substrate. When the present film is further laminated to a substrate, the peel strength to the substrate is preferably 10 N / cm or more, more preferably 15 N / cm or more, and preferably 100 N / cm or less.

[0047] Polymer layers (films) formed from the present composition are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, heat dissipation parts, and the like. Specifically, these include electric wire coating materials (aircraft electric wires, rectangular wires, FFC (Flexible Flat Cable), etc.), enameled wire coating materials used in motors for electric vehicles, etc., power generation coating materials, electrical insulating tape, insulating tape for oil drilling, oil transport hoses, hydrogen tanks, materials for printed circuit boards, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), carrier films for fuel cells, tape base films for semiconductor manufacturing processes (dicing tape, pick-up tape, etc.), release films for semiconductor molding, liquid crystal antennas, reflectors, transmission lines, COF (Chip on Fibre), base films for electrostatic chucks used in semiconductor manufacturing processes, electrostatic chucks used in display manufacturing processes, copy rolls, furniture, automobile dashboards, covers for home appliances, etc., sliding parts (load bearings, yaw bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear rings, 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, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, racket strings, dies, toilets, container coating materials, heat dissipation substrates for mounting power devices, heat dissipation materials for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOS It is useful for FETs, CPUs, heat dissipation fins, metal heat sinks, blades for wind turbines, wind power generation equipment, aircraft, etc., housings for personal computers and displays, electronic device materials, interior and exterior parts of automobiles, sealing materials for processing machines and vacuum ovens that perform heat treatment under low oxygen conditions, plasma processing equipment, etc., heat dissipation parts in processing units for sputtering and various dry etching equipment, etc., and electromagnetic wave shielding. Furthermore, this film is particularly useful as an electromagnetic wave reflector (reflector array), also known as a metasurface reflector, a metasurface substrate, a solar cell surface release plate, or a transparent cover film for solar cell module components in various electronic devices such as smartphones and tablet computers that are equipped with a display panel, such as a liquid crystal, organic light-emitting diode, or OLED display panel, and a transparent antenna.

[0048] The present composition and the polymer layer (film) formed from the present composition have been described above, but the present invention is not limited to the configurations of the above-described embodiments. For example, the present composition and the polymer layer (film) formed from the present composition may have any other structure added to the structure of the above embodiment, or may be replaced with any structure that exhibits a similar function. [Example]

[0049] 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 ingredient [Thermal melting tetrafluoroethylene polymer (F polymer)] The following five types of resin particles were prepared: All of the resin particles were substantially free of a fluorine-containing compound having a hydrophilic group. Resin particles 1: It contains TFE units, NAH units, and PPVE units, and has a carbonyl group-containing group with a main chain carbon number of 1 × 10 6 Particles of F polymer 1 (MFR: 17.6 g / 10 min, melting point: 300 °C) with 1000 particles per particle (D50: 2.1 μm) Resin particles 2: It contains TFE units and PPVE units, and the carbonyl group-containing group has a main chain carbon number of 1 × 10 6 Particles of F polymer 2 (MFR: 34.6 g / 10 min, melting point: 295 °C) with 250 particles per particle (D50: 9.0 μm) Resin particles 3: It contains TFE units and PPVE units, and the carbonyl group-containing group has a main chain carbon number of 1 × 10 6Particles of F polymer 3 (MFR: 14.0 g / 10 min, melting point: 300 °C) with 35 particles per particle (D50: 2.0 μm) Resin particles 4: It contains TFE units and PPVE units, and the carbonyl group-containing group has a main chain carbon number of 1 × 10 6 Particles of F Polymer 4 (MFR: 6.0 g / 10 min, melting point 305 ° C) with less than 10 particles per particle (D50: 2.4 μm) Resin particles 5: It contains TFE units and HFP units, and the carbonyl group-containing group has a main chain carbon number of 1 × 10 6 Particles of F Polymer 5 (MFR: 15.0 g / 10 min, melting point: 260°C) with 30 particles per particle (D50: 2.7 μm)

[0050] 2. Example of production of liquid composition [Manufacturing Example 1] Water, resin particles 1, and resin particles 4 were placed in a planetary centrifugal mixer (Thinky Corporation, product name "Awatori Rentaro (registered trademark) ARE-310"; the same applies below), kneaded at 2000 rpm for 1 minute, and further water was added to obtain a slurry-like liquid composition 1 having a resin particle 1 content of 5% by mass and a resin particle 4 content of 40% by mass. [Manufacturing Example 2] A slurry liquid composition 2 containing 5% by mass of resin particles 1 and 40% by mass of resin particles 3 was obtained in the same manner as in Production Example 1, except that resin particles 4 were replaced with resin particles 3. [Manufacturing Example 3] A slurry liquid composition 3 was obtained in the same manner as in Production Example 1, except that resin particles 1 were replaced with resin particles 2, with the resin particles 2 content being 5% by mass and the resin particles 3 content being 40% by mass. [Manufacturing Example 4] A slurry-like liquid composition 4 was obtained in the same manner as in Production Example 1, except that resin particles 1 were replaced with resin particles 2 and resin particles 4 with resin particles 5, with the content of resin particles 2 being 5% by mass and the content of resin particles 5 being 40% by mass. [Manufacturing Example 5] A slurry-like liquid composition 5 was obtained in the same manner as in Production Example 1, except that resin particles 1 were changed to resin particles 2 and resin particles 4 to resin particles 3, and the blending amounts were also changed. The slurry-like liquid composition 5 had a resin particle 2 content of 25% by mass and a resin particle 3 content of 25% by mass.

[0051] 3. Production examples and evaluation of polymer layers (films) from liquid compositions 3-1. Polymer layer manufacturing example [Example 1] The liquid composition 1 obtained above was applied to the surface of a polyimide film by a die coating method using a roll-to-roll process to form a coating layer. The polyimide film with this coating layer formed was then passed through a drying oven at 120°C for 3 minutes to dry it and form a dry film. The polyimide film with the dry film was then passed through a far-infrared oven at 350°C for 5 minutes to melt and sinter the resin particles, forming an F polymer layer containing the molten and sintered product of resin particles 1 and resin particles 4 on one side of the copper foil, thereby obtaining laminated film 1 having an F polymer layer and a polyimide layer. [Example 2]~[Example 5] Laminated films 2 to 5 were obtained in the same manner as in Example 1, except that Liquid compositions 2 to 5 were used instead of Liquid composition 1, respectively.

[0052] 3-2.Evaluation The appearance, bending durability and adhesiveness of the resulting laminated film were evaluated by the following evaluation methods. <Appearance> The surface of the polymer layer of each laminate film was visually observed, and the appearance was evaluated by assigning "good" when no streaks or wrinkles were observed, and "poor" when streaks or wrinkles were observed. <Bending durability> Test pieces (5 mm square) were cut out from each laminate film, and the test pieces were bent 180° with a radius of curvature (300 μm). A load (50 mN, 1 minute) was applied from above, and the appearance of the laminate film test pieces was observed when they were unfolded. If no abnormalities in appearance were observed at the fold, they were evaluated as "Good", and if the fold turned white or broke, they were evaluated as "Poor". <Adhesiveness> A test piece (100 mm long, 10 mm wide) was cut from the laminated film, and the polyimide layer and polymer layer were peeled from one end of the test piece to a position 50 mm from one end in the longitudinal direction. Next, using a tensile tester (manufactured by Orientec Co., Ltd.), the test piece was centered at a position 50 mm from one end in the longitudinal direction and peeled at a 90-degree angle at a pulling rate of 50 mm / min. The maximum load was recorded as the peel strength (N / cm). Adhesion was evaluated by rating a peel strength of 10 N / cm or more as "good" and a peel strength of less than 10 N / cm as "poor." The results are shown in Table 1.

[0053] [Table 1]

[0054] 4. Preparation and evaluation of films from powder compositions 4-1. Film manufacturing example [Example 6] A powdery composition containing 10% by mass of F polymer 1 and 90% by mass of F polymer 4 was fed into a multi-screw extruder, melted at 330°C, and extruded through a die into a film, thereby obtaining a film 1 having a thickness of 100 μm. [Example 7] Film 2 was obtained in the same manner as in Example 6, except that F Polymer 4 was changed to F Polymer 3. [Example 8] Film 3 was obtained in the same manner as in Example 6, except that F Polymer 1 was changed to F Polymer 2 and F Polymer 4 was changed to F Polymer 3. [Example 9] Film 4 was obtained in the same manner as in Example 6, except that F Polymer 1 was changed to F Polymer 2 and F Polymer 4 was changed to F Polymer 5. [Example 10] Film 5 was obtained in the same manner as in Example 6, except that F polymer 1 was changed to F polymer 2, F polymer 4 was changed to F polymer 3, and the blending amounts of F polymer 2 and F polymer 3 were changed to 50 mass% and 50 mass%, respectively.

[0055] Evaluation The dimensional stability and adhesiveness of the resulting film were evaluated by the following evaluation methods. <Film dimensional stability> Each film was cut into a length (MD) x width (TD) of 12 cm to obtain a sample. At 25°C, two straight lines, each 10 cm ± 0.2 cm long, were drawn on the sample in both the MD and TD directions, and the average distance between the endpoints of each line measured to the nearest 0.01 cm using a Mitutoyo QuickVision CNC image measuring instrument was taken as the initial length L0. The sample was heat-treated at 150°C for 15 minutes and cooled to 25°C. The linear distance L1 between the endpoints of the lines drawn on the sample was then measured in the same manner as for L0. The dimensional change rate (%) was calculated using the following formula 1, and the dimensional stability was evaluated according to the following criteria. Dimensional change rate (%) = (L1 / L0-1) × 100 Formula 1 Evaluation Criteria ○: Dimensional change rate is less than 2% ×: Dimensional change rate is 2% or more <Film adhesiveness> Copper-clad films having a film layer and a copper foil layer were prepared from each film by heat-pressing the film and copper foil together. The copper-clad films were cut to a width of 1 cm, and the film layer and the copper foil layer were peeled from one end of the film to a position 50 mm in the longitudinal direction. The peel strength (N / cm) was measured using a tensile tester at 25°C, a pulling rate of 100 mm / min, and a 90° angle. The average load measured over a distance of 20 mm to 80 mm was recorded as the peel strength. Adhesion was evaluated by assigning a "good" rating to peel strengths of 10 N / cm or greater and an "unsatisfactory" rating to peel strengths of less than 10 N / cm. The results are shown in Table 2.

[0056] [Table 2] [Industrial Applicability]

[0057] The composition of the present invention can be used to form molded articles such as polymer layers and films that have high physical properties of tetrafluoroethylene polymers, excellent heat resistance, small dimensional change, and excellent surface properties and adhesiveness, and can therefore be effectively used for various components such as printed circuit boards.

Claims

1. A composition comprising two types of heat-meltable tetrafluoroethylene-based polymers whose difference in melt flow rate (MFR) has an absolute value of 10 or more, one of the heat-meltable tetrafluoroethylene-based polymers having an oxygen-containing polar group, the MFR of one of the heat-meltable tetrafluoroethylene-based polymers being greater than the MFR of the other heat-meltable tetrafluoroethylene-based polymer, and the content of the other heat-meltable tetrafluoroethylene-based polymer being greater than the content of one of the heat-meltable tetrafluoroethylene-based polymers.

2. The composition according to claim 1, wherein the two types of heat-fusible tetrafluoroethylene-based polymers are each contained in the form of particles.

3. The one of the heat-meltable tetrafluoroethylene-based polymers has an MFR of 15 g / 10 min or more, and the number of the oxygen-containing polar groups is 10 or more. ６ The composition of claim 1, wherein the number of particles is 200 or more per particle.

4. the other heat-meltable tetrafluoroethylene-based polymer has an MFR of less than 15 g / 10 min and the number of oxygen-containing polar groups is 10 or less ６ The composition of claim 1, wherein the number of particles is less than 200 per particle.

5. 2. The composition according to claim 1, wherein the absolute value of the difference between the MFR of said one heat-meltable tetrafluoroethylene-based polymer and the MFR of said other heat-meltable tetrafluoroethylene-based polymer is 50 or less.

6. 2. The composition according to claim 1, wherein the melting point of said one hot-melt tetrafluoroethylene-based polymer and the melting point of said other hot-melt tetrafluoroethylene-based polymer are each 200°C or higher and 320°C or lower, and the absolute value of the difference between the melting points is within 25°C.

7. 7. The composition according to claim 6, wherein the melting point of said one heat-meltable tetrafluoroethylene-based polymer is equal to or lower than the melting point of said other heat-meltable tetrafluoroethylene-based polymer.

8. 2. The composition according to claim 1, wherein the content of the one heat-meltable tetrafluoroethylene-based polymer is 5% by mass or more and 25% by mass or less relative to the total content of the one heat-meltable tetrafluoroethylene-based polymer and the other heat-meltable tetrafluoroethylene-based polymer.

9. 2. The composition according to claim 1, wherein the content of the fluorine-containing compound having a hydrophilic group is 250 ppb by mass or less based on the total content of the one heat-fusible tetrafluoroethylene-based polymer and the other heat-fusible tetrafluoroethylene-based polymer.

10. The particles of the one of the heat-meltable tetrafluoroethylene polymers have an average particle size of 0.1 μm or more and 40 μm or less and a specific surface area of ​​6 m ２ / g or more 40m ２ 3. The composition of claim 2, wherein the particles are 0.1g or less.

11. 3. The composition according to claim 2, further comprising a liquid dispersion medium in which the particles of said one heat-fusible tetrafluoroethylene-based polymer and the particles of said other heat-fusible tetrafluoroethylene-based polymer are dispersed.

12. The composition of claim 1 in powder or pellet form.

13. A method for producing a polymer layer, comprising placing the composition according to claim 11 on a surface of a substrate and heating the composition to form a polymer layer containing the one heat-fusible tetrafluoroethylene-based polymer and the other heat-fusible tetrafluoroethylene-based polymer.

14. A film formed by extruding or disposing the composition according to any one of claims 1 to 12 on the surface of a substrate.

15. 15. The film according to claim 14, wherein the absolute values ​​of the dimensional changes in MD and TD before and after heat treatment are within 2% when heat-treated for 10 minutes at 180°C and then cooled to 25°C and measured, and the oxygen element ratio is 0.1 atomic% or more when the surface condition of one or both sides of the film after heat treatment for 3 minutes at 180°C is measured by scanning X-ray photoelectron spectroscopy (XPS / ESCA).

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