Methods for manufacturing liquid compositions, laminates and the like

Abstract

This invention provides a liquid composition with excellent uniformity and dispersion stability and low viscosity, a method for manufacturing the liquid composition, a method for manufacturing a laminate, and the laminate having a polymer layer obtained from the composition, wherein the polymer layer exhibits excellent adhesion to a substrate, thermal conductivity, heat resistance, and electrical properties. The aforementioned liquid composition comprises: tetrafluoroethylene-based polymer particles; spherical silicon oxide with a median particle size d (μm) greater than 0.6 μm and less than 20 μm, and the product of the median particle size d and the specific surface area A (m² / g), d×A, is 2.7~5.0 μm·m² / g; and a liquid dispersion medium.

Description

Technical Field

[0001] This invention relates to a liquid composition having a tetrafluoroethylene-based polymer and silicon oxide, and a method for manufacturing the same, as well as a laminate having a polymer layer formed from the liquid composition and a method for manufacturing the same. Prior Technology

[0002] In recent years, in order to cope with the high speed and high frequency of mobile communication devices such as mobile phones, there is a search for materials with high thermal conductivity, low coefficient of linear expansion, low dielectric constant and low dielectric tangent for printed circuit board materials of communication devices. Polytetrafluoroethylene polymers with low dielectric constant and low dielectric tangent are attracting attention. Various investigations have been conducted to obtain materials containing tetrafluoroethylene-based polymers with superior physical properties. For example, Patent Document 1 discloses a laminated body formed by coating a liquid composition containing a tetrafluoroethylene-based polymer and specific silicon oxide particles onto a substrate. Patent Document 2 describes the addition of a non-aqueous dispersion containing polytetrafluoroethylene, ceramic microparticles, and specific fluorine additives to various resin materials. Previous technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-183005 Patent Document 2: Japanese Patent Application Publication No. 2016-194017 Summary of the Invention

[0004] The problem the invention aims to solve Tetrafluoroethylene polymers have low surface tension and low affinity for inorganic particles and other components. Therefore, in the case of molded articles formed from compositions containing tetrafluoroethylene polymers and inorganic particles, there may be insufficient dispersion of inorganic particles and incomplete expression of the physical properties of each component. Regarding the liquid composition described in Patent Document 1, from the viewpoint of exhibiting a linear expansion suppression effect in the resulting molded article with a relatively small amount of added silicon oxide, suitable silicon oxide particles include mesoporous silicon oxide particles, microporous silicon oxide particles, and hollow silicon oxide particles with a specific surface area of ​​6.5 m² / g or more. In other words, from the viewpoint of further enhancing the properties of silicon oxide by increasing the amount of added silicon oxide, there is still room for improvement. The non-aqueous dispersion described in Patent Document 2 has the problem that when the type or amount of ceramic microparticles as inorganic particles is increased, or other components are further mixed in, the uniformity and dispersion stability of the composition are reduced, making it difficult to obtain polymer layers and other shaped products with sufficient properties.

[0005] The inventors observed that by using tetrafluoroethylene-based polymer particles and specific spherical silicon oxide, a liquid composition with excellent uniformity and dispersion stability, and with suppressed thickening, can be obtained. Furthermore, it was discovered that a thick polymer layer can be formed from the liquid composition, exhibiting excellent adhesion to a substrate, thermal conductivity, heat resistance, dielectric tangent, and other electrical properties. The laminate system having this polymer layer is suitable as a material for printed wiring boards, etc., thus completing the present invention. The present invention aims to provide a liquid composition with excellent uniformity and dispersion stability and low viscosity, a method for manufacturing the liquid composition, a method for manufacturing a laminate having a polymer layer obtained from the composition, and the laminate.

[0006] The means to solve the problem The present invention has the following characteristics. [1] A liquid composition comprising: tetrafluoroethylene polymer particles; spherical silicon oxide, wherein the median particle size d (μm) is greater than 0.6 μm and less than 20 μm, and the product of the aforementioned median particle size d and specific surface area A (m 2 / g), d×A, is 2.7~5.0 μm･m 2 / g; and a liquid dispersion medium. [2] As in [1], the liquid composition, wherein the aforementioned tetrafluoroethylene polymer is a hot-melt tetrafluoroethylene polymer. [3] Liquid composition as in [1] or [2], wherein the aforementioned tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group, which contains units mainly composed of perfluorinated (alkyl vinyl ethers). [4] The liquid composition of any one of [1] to [3], wherein the specific surface area of ​​the aforementioned spherical silicon oxide is 0.2 to 2.0 m² / g. [5] The liquid composition of any one of [1] to [4], wherein the maximum IR peak intensity of the aforementioned spherical silicon oxide surface, which originates from bonded silanol groups and is located at 3300~3700 cm⁻¹, is less than 0.2.

[0007] [6] The liquid composition of any one of [1] to [5], wherein the content of the aforementioned spherical silicon oxide is 10 to 60% by mass relative to the total mass of the aforementioned liquid composition, the content of the aforementioned tetrafluoroethylene polymer particles is 10 to 40% by mass, and the content of the aforementioned liquid dispersion medium is 5% by mass or more. [7] The liquid composition of any one of [1] to [6], wherein the content of the aforementioned spherical silicon oxide is greater than the content of the aforementioned tetrafluoroethylene polymer particles. [8] A liquid composition of any of [1] to [7] further comprises a surfactant. [9] A liquid composition of any of [1] to [8] further comprises an aromatic polymer.

[10] The liquid composition of any one of [1] to [9] further comprises an inorganic filler different from the aforementioned spherical silicon oxide.

[11] The liquid composition of any one of [1] to

[10] has a viscosity of 50 to 1000 mPa·s.

[0008]

[12] A method for manufacturing a liquid composition as described in any one of [1] to

[11] is to obtain the liquid composition by mixing the aforementioned tetrafluoroethylene polymer particles, the aforementioned spherical silicon oxide and the aforementioned liquid dispersion medium.

[13] A method for manufacturing a liquid composition, comprising manufacturing a liquid composition as described in any one of [1] to

[11] , the method being as follows: A composition containing the aforementioned tetrafluoroethylene polymer particles, the aforementioned spherical silicon oxide, and a portion of the aforementioned liquid dispersion medium is kneaded together to obtain a kneaded compound. The remaining aforementioned liquid dispersion medium is then added to the kneaded compound and mixed to obtain the aforementioned liquid composition.

[14] A method for manufacturing a laminate involves applying a liquid composition as described in any one of [1] to

[11] to the surface of a substrate to form a liquid film composed of the aforementioned liquid composition, followed by heating to remove the aforementioned liquid dispersion medium from the aforementioned liquid film, and forming a polymer layer comprising the aforementioned tetrafluoroethylene polymer and the aforementioned spherical silicon oxide on the surface of the aforementioned substrate.

[15] A laminate has: a substrate; and a polymer layer disposed on the surface of the substrate and formed of a liquid composition as described in any one of [1] to

[11] , including a tetrafluoroethylene polymer and the aforementioned spherical silicon oxide.

[0009] Invention Effects According to the present invention, a liquid composition with excellent uniformity and dispersion stability and low viscosity can be provided, a method for manufacturing the liquid composition, a method for manufacturing a laminate, and the laminate having a polymer layer obtained from the composition, wherein the polymer layer has excellent adhesion to a substrate, thermal conductivity, heat resistance and electrical properties. Implementation

[0010] The following terms have the following meanings. "Melting temperature of the polymer" refers to the temperature corresponding to the maximum value of the melting peak as determined by differential scanning calorimetry (DSC). The glass transition point of polymers is a value determined by analyzing polymers using the dynamic viscoelasticity (DMA) method. The "average particle size of tetrafluoroethylene polymer particles" is determined by laser diffraction and scattering, and the particle size is accumulated at 50% of the volume (hereinafter also denoted as "D50"). That is, by determining the particle size distribution of the particles by laser diffraction and scattering, and calculating the cumulative curve with the total volume of the particle group as 100%, the particle size at the point where the cumulative volume of the cumulative curve is 50% is obtained. The "specific surface area of ​​particles" is a value determined by the BET multi-point method of gas adsorption (constant volume method). "Viscosity" is measured using a Type B viscometer at room temperature (25°C) and a rotation speed of 30 rpm on the dispersion. The measurement was repeated three times, and the average of the three measurements was taken as the viscosity. The "thixotropic ratio" refers to the value (η1 / η2) calculated by dividing the viscosity η1 of a liquid composition measured at 30 rpm by the viscosity η2 measured at 60 rpm. "A unit based on a monomer" refers to a group of atoms formed by the polymerization of a monomer, with one molecule of the aforementioned monomer as the main component. A unit can be formed directly through a polymerization reaction, or it can be a unit whose structure is transformed by processing the polymer. The unit based on monomer a below will simply be denoted as "monomer a unit".

[0011] The liquid composition of the present invention (hereinafter also referred to as "this composition") comprises: tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") particles (hereinafter also referred to as "F particles"); spherical silicon oxide (hereinafter also referred to as "this spherical silicon oxide"), wherein the median particle size d (μm) is greater than 0.6 μm and less than 20 μm, and the product of the aforementioned median particle size d and specific surface area A (m 2 / g), d×A, is 2.7~5.0 μm·m 2 / g; and a liquid dispersion medium. This composition exhibits excellent uniformity and dispersion stability, and has low viscosity. Furthermore, a thick polymer layer can be obtained from this composition, exhibiting excellent adhesion to the substrate, thermal conductivity, heat resistance, and low dielectric tangent. The laminated system having the aforementioned polymer layer is suitable as a material for printed wiring boards and the like, possessing excellent adhesion, thermal conductivity, and electrical properties. The reasons for the properties exhibited by this composition are not yet clear, but can be inferred, for example, as follows.

[0012] The F polymer has low surface energy, making its particles prone to aggregation. Furthermore, the F polymer has low affinity for inorganic particles such as silicon oxide, leading to the easy formation of aggregates of inorganic particles in polymer layers containing both F polymers and inorganic particles. This tendency becomes more pronounced when the content of inorganic particles is high. The spherical silicon oxide used in this composition (the spherical silicon oxide itself) has a median particle size d within the aforementioned specific range, and the product of the aforementioned median particle size d and the specific surface area A, d×A, is within a specific range. Therefore, we determine that not only is the aggregation of silicon oxide particles suppressed in this composition, but the wettability of silicon oxide with the liquid dispersion medium is also adjusted, thus relatively increasing the affinity between the spherical silicon oxide and the F polymer. We believe this is because it promotes a high degree of interaction between the F particles and the spherical silicon oxide, resulting in excellent dispersion stability, low viscosity, and other physical properties of this composition. Furthermore, we also hypothesize that, for this composition in which the two particles are in a state of high interaction, the self-coagulation of F particles and the spherical silica is easily promoted; in other words, the formation of pseudo-coalescent particles of F particles and spherical silica is easily promoted. We judge that this is because it improves the homogeneity of this composition, thus resulting in excellent dispersion stability, low viscosity, and other physical properties.

[0013] Furthermore, if the composition consists of highly interacting two particles and exhibits excellent properties such as dispersion stability and low viscosity, the spherical silica will be difficult to shed even during or after the molding process, and the spherical silica will be easily and highly dispersed within the molded product. As a result, we determined that this composition can easily form molded products that highly possess the properties of both the original silica and the F polymer, and exhibit excellent electrical properties such as adhesion to the substrate, thermal conductivity, heat resistance, and low dielectric tangent.

[0014] The F polymer in this composition comprises a polymer with tetrafluoroethylene (TFE) as the main component (TFE unit). The F polymer can be either hot-melt or non-hot-melt. For this composition, a hot-melt F polymer is preferred. In addition, hot-melt polymers refer to polymers that, under a load of 49N, have a melt flow rate of 1~1000g / 10min at a temperature 20°C or higher than the polymer's melting temperature. Two or more polymers can also be used.

[0015] The melting temperature of the hot-melt polymer F is preferably above 200°C, and more preferably above 260°C. The melting temperature of polymer F is preferably below 325°C, and more preferably below 320°C. Under these conditions, the molded articles formed from this composition readily exhibit excellent heat resistance. The fluorine content in the F polymer should preferably be above 70% by mass, with 72-76% by mass being more desirable. According to this method, through the above-mentioned mechanism, even when using an F polymer with high fluorine content and low affinity for inorganic particles, it is still easy to obtain a polymer layer with excellent dispersibility of the spherical silicon oxide. The glass transition point of polymer F should preferably be above 50°C, with above 75°C being preferable. The glass transition point of polymer F should preferably be below 150°C, with below 125°C being preferable.

[0016] Examples of polymers containing F include: polymers containing polytetrafluoroethylene (PTFE), TFE units, and ethylene units; polymers containing TFE units and propylene units; polymers containing TFE units and units primarily composed of perfluoro(alkyl vinyl ether) (PAVE) units (PFA); polymers containing TFE units and hexafluoropropylene units (FEP); polymers containing TFE units and units primarily composed of fluoroalkyl vinyl groups; and polymers containing TFE units and trichlorofluoroethylene units. PTFE can be either non-meltable or meltable. Polymer F is preferably PFA and FEP, with PFA being preferred. These polymers may also further contain units based on other comonomers. PAVE should ideally be CF 2=CFOCF 3, CF 2=CFOCF 2CF 3 and CF 2=CFOCF 2CF 2CF 3 (hereinafter also referred to as PPVE), with PPVE being preferred.

[0017] The F polymer preferably has oxygen-containing polar groups. When the F polymer has oxygen-containing polar groups, the affinity between the F particles and the spherical silicon oxide is easily increased, and the spherical silicon oxide is easily well dispersed in the polymer layer. Furthermore, we have determined that cross-linking of the F polymer is easily formed when the composition is heated, and a polymer layer with excellent mechanical properties is easily obtained. In particular, as long as the aforementioned F polymer is used, the above-mentioned mechanism of action, especially the effect of self-aggregation, is easily and highly manifested. Oxygen-containing polar groups can be contained in monomer-based units of F polymers, or they can be contained in the terminal groups of the F polymer backbone. Examples of the latter include: F polymers with oxygen-containing polar groups as terminal groups derived from polymerization initiators, chain transfer agents, etc., and F polymers with oxygen-containing polar groups obtained by plasma treatment or free radiation treatment of F polymers.

[0018] When the F polymer has oxygen-containing polar groups, the number of oxygen-containing polar groups in the F polymer, relative to the number of carbons per main chain (1×10⁶), should preferably be 100~10000, with 500~5000 being more preferred. The oxygen-containing polar group is preferably a hydroxyl group, a carbonyl group, or an isophosphorus group. From the viewpoint of the dispersibility of the spherical silicon oxide in the polymer layer, hydroxyl groups and carbonyl groups are preferred, with carbonyl groups being even better.

[0019] The hydroxyl group should preferably contain an alcoholic hydroxyl group, such as -CF2CH2OH, -C(CF3)2OH and 1,2-diol group (-CH(OH)CH2OH). The carbonyl group includes carbonyl (>C(O)) groups. The carbonyl group is preferably a carboxyl group, alkoxycarbonyl group, amide group, isocyanate group, carbamate group (-OC(O)NH 2), acid anhydride residue (-C(O)OC(O)-), amide imine residue (-C(O)NHC(O)-, etc.) and carbonate group (-OC(O)O-), with acid anhydride residues being preferred. The aforementioned carbonyl-containing group can be contained in the monomer unit of the F polymer, or it can be contained in the terminal group of the polymer backbone. An example of the latter is an F polymer that uses the aforementioned carbonyl-containing group as a terminal group derived from a polymerization initiator, chain transfer agent, etc. When polymer F contains carbonyl groups, the number of carbonyl groups in polymer F, relative to the number of carbon atoms per main chain (1 × 10⁶), should preferably be 100–10,000, with 500–5,000 being more preferred and 800–1,500 being even better. At this point, the affinity of polymer F for the spherical silicon oxide is easily enhanced. In addition, the number of carbonyl groups in polymer F can be quantified by means of the polymer composition or by the methods described in International Publication No. 2020 / 145133.

[0020] Polymer F is preferably a polymer containing TFE units and PAVE units and having oxygen-containing polar groups; polymers containing TFE units and PAVE units and having carbonyl or hydroxyl groups are more preferred; polymers containing TFE units, PAVE units, and units mainly composed of monomers having carbonyl groups are even more preferred. Relative to all units, polymer F is particularly preferably composed of 90-99 mol% TFE units, 0.5-9.97 mol% PAVE units, and 0.01-3 mol% of the aforementioned units mainly composed of monomers having carbonyl groups. Monomers containing a carbonyl group are preferably itanic anhydride, citraconic anhydride, and 5-norcamphen-2,3-dicarboxylic anhydride (hereinafter also denoted as "NAH"). Specific examples of the polymer may be the polymer described in International Publication No. 2018 / 16644. These F polymers not only exhibit excellent particle dispersion stability, but also tend to have a fine and homogeneous distribution in molded articles (polymer layers, etc.) obtained from this composition. Furthermore, microspheres are easily formed in the molded articles, and their adhesion to other components, primarily the spherical silicon oxide, is readily increased. As a result, it is easier to obtain molded articles with excellent electrical properties and other physical properties.

[0021] In this composition, the D50 of the F particles is preferably below 25 μm, below 10 μm is preferred, and below 8 μm is even better. The D50 of the F particles is preferably above 0.1 μm, above 0.3 μm is preferred, and above 1 μm is even better. At this point, the inhibition of particle aggregation and the interaction between the F particles and the spherical silicon oxide are highly balanced, thus easily improving the dispersion stability of this composition. Furthermore, the spherical silicon oxide is easily and highly dispersed in the polymer layer.

[0022] The bulk density of F particles should preferably be above 0.15 g / m². The bulk density of F particles should preferably be below 0.50 g / m². Furthermore, the specific surface area of ​​F particles should preferably be below 25 m² / g, preferably below 8 m² / g, and even better below 5 m² / g. The specific surface area of ​​F particles should preferably be above 1 m² / g. At this point, particle aggregation is highly suppressed, and the interaction between F particles and the spherical silicon oxide is easily enhanced.

[0023] Two or more types of F particles can also be used. When using two types of F particles, the F particles should preferably include thermomeltable F polymer particles and non-thermally meltable F polymer particles, preferably including F polymer particles with a melting temperature of 200~320°C (suitable for the above-mentioned polymers containing TFE units and PAVE units and having oxygen-containing polar groups) and non-thermally meltable PTFE particles. Furthermore, it is better if the content of the latter particles is higher than the content of the former particles. At this point, the F polymer maintains its physical properties while becoming moderately fibrous, making it easier to hold F particles in the molded article formed from this composition, and the strength of the molded article can be further improved. Furthermore, the proportion of the former particles in the total of the former and latter particles should preferably be less than 50% by mass, and less than 25% by mass is preferable. Also, in this case, the proportion should preferably be more than 0.1% by mass, and more than 1% by mass is preferable. The composition not only exhibits excellent dispersion stability, uniformity, and handling properties, but also readily forms adhesive molded articles with excellent physical properties based on non-thermally meltable PTFE. Furthermore, at this time, it is advisable to have the following states: F polymer particles with a melting temperature of 200~320℃ and a D50 of 0.1~1μm and non-thermally fusible PTFE particles with a D50 of 0.1~1μm, or F polymer particles with a melting temperature of 200~320℃ and a D50 of 1~4μm and non-thermally fusible PTFE particles with a D50 of 0.1~1μm. In addition, non-thermally molten polymers refer to polymers that do not reach a melt flow rate of more than 1g and less than 1000g per 10 minutes under a load of 49N.

[0024] F particles may also contain resins or inorganic substances other than F polymers, but F polymers should preferably be the main component. The content of F polymers in F particles should preferably be above 80% by mass, and 100% by mass is preferred.

[0025] The spherical silicon oxide in this composition is solid silicon oxide with a median particle size d (μm) greater than 0.6 μm and less than 20 μm. Furthermore, the product of the aforementioned median particle size d and specific surface area A (m² / g), d×A, is in the range of 2.7~5.0 μm·m² / g (2.7 ≤ A×d50 (μm·m² / g) ≤ 5.0). If the median particle size d is greater than 0.6 μm, the dielectric tangent can be significantly reduced. On the other hand, if the median particle size d increases, the value of the grid gauge (measured using the JIS K5400 grid gauge method) increases. When forming this composition, for example, into a polymer layer, from the viewpoint of controlling the minimum thickness of the polymer layer, the median particle size d should preferably be greater than 0.6 μm and less than 10 μm, and more preferably 1 to 5 μm. Furthermore, the median particle size d of this spherical silicon oxide was obtained using a laser diffraction particle size distribution measuring device (e.g., Microtrac BEL Co., Ltd.'s "MT3300EXII"). Specifically, the spherical silicon oxide powder was dispersed by irradiating it with ultrasound for 60 seconds three times in the device, and then measured twice for 60 seconds each time to obtain the average value.

[0026] The product of the median particle size d and the specific surface area A in this spherical silicon oxide, d×A, is 2.7~5.0 μm·m² / g, preferably 2.7~4.5 μm·m² / g, and more preferably 2.7~4.0 μm·m² / g. The theoretical value of d×A is 2.7 (derived from specific surface area = 6 / (true density of silicon oxide 2.2 × median particle size d)), and values ​​below this are unattainable in practice. Since a larger value of d×A results in a larger specific surface area per particle size, leading to a larger dielectric tangent, d×A is set to below 5.0 μm·m² / g in order to reduce the dielectric tangent to below approximately 0.0020 at a frequency of 1 GHz.

[0027] The specific surface area A of this spherical silicon oxide is preferably in the range of 0.2~2.0 m² / g. If the specific surface area is 0.2 m² / g or higher, when this composition contains this spherical silicon oxide, it has sufficient contact points with polymer F, thus improving its compatibility with polymer F. If it is 2.0 m² / g or lower, the dielectric tangent can be reduced, thus the molded article obtained from this composition exhibits excellent low dielectric tangent and improved dispersibility. Furthermore, we believe that, for this spherical silicon oxide, the presence of small median particle size or a rough surface helps to suppress the thickening of this composition. The specific surface area A should ideally be below 1.5 m² / g, preferably below 1.0 m² / g, and especially below 0.8 m² / g. Furthermore, it is practically difficult to obtain substances with a specific surface area A less than 0.2 m² / g. In addition, the specific surface area of ​​this spherical silicon oxide was obtained by the BET method, which is based on nitrogen adsorption using a specific surface area and pore distribution measuring device (e.g., Microtrac BEL's "BELSORP-miniII", Micromeritics' "TriStar II").

[0028] The true sphericity of this spherical silicon oxide should preferably be 0.75~1.0. If the true sphericity decreases, the specific surface area increases. Therefore, in order to facilitate the increase of dielectric tangent, the true sphericity should preferably be 0.75 or higher. A true sphericity of 0.90 or higher is preferred, 0.93 or higher is even better, and the closer to 1.0, the better. In addition, true sphericity can be expressed as the average value of the ratio of the minimum diameter (DS) to the maximum diameter (DL) (DS / DL). The maximum diameter (DL) and minimum diameter (DS) are determined as follows: for any 100 particles in a photographic projection image obtained by scanning electron microscopy (SEM), the individual maximum diameter (DL) and the minor diameter (DS) orthogonal to it are measured.

[0029] The dielectric tangent of this spherical silicon oxide should preferably be below 0.0020, more preferably below 0.0010, and even more preferably below 0.0008 at a frequency of 1 GHz. If the aforementioned dielectric tangent is below 0.0020, excellent dielectric loss suppression can be achieved, thus obtaining a substrate or sheet with improved high-frequency characteristics. Since a smaller dielectric tangent can better suppress transmission losses in the circuit, there is no particularly limited lower limit value. Alternatively, dielectric tangent can be measured using a dedicated device (e.g., the "Vector Network Analyzer E5063A" manufactured by KEYCOM Ltd.) and using the perturbation resonator method (measurement conditions: test frequency 1 GHz, test temperature approximately 24°C, humidity approximately 45%, and 3 measurements).

[0030] The spherical silicon oxide is preferably a spherical silicon oxide whose viscosity, as determined by the following method, is 5000 mPa·s or less. Determination method: Mix 6 parts by mass of cooked linseed oil as specified in JIS K 5421:2000 with 8 parts by mass of spherical silicon oxide, and knead at 2000 rpm for 3 minutes to obtain a kneaded mixture. Use a rotational rheometer to measure the viscosity of the kneaded mixture at a shear rate of 1 s⁻¹ for 30 seconds to obtain the viscosity at 30 seconds.

[0031] The IR peak intensity near 3746 cm⁻¹ originating from isolated silanol groups on the surface of this spherical silicon oxide is preferably below 0.1, more preferably below 0.08, and even better below 0.06. Isolated silanol groups refer to silanol (Si-OH) groups that are not bonded to water or other substances adsorbed on the silicon oxide particles. The amount of isolated silanol (Si-OH) on the surface of the silicon oxide particles is obtained by IR measurement. Specifically, the IR spectrum is standardized at 800 cm⁻¹, and the baseline is matched at 3800 cm⁻¹. The relative value of the Si-OH peak intensity near 3746 cm⁻¹ is then calculated. If the IR peak intensity near 3746 cm⁻¹ originating from isolated silanol groups on the surface of this spherical silicon oxide is below 0.1, dielectric loss can be reduced.

[0032] Furthermore, the maximum IR peak intensity of the spherical silicon oxide surface, originating from bonded silanol groups and located in the 3300–3700 cm⁻¹ range, should preferably be below 0.2, more preferably below 0.17, and even more preferably below 0.15. Bonded silanol groups refer to silanol (Si-OH) groups bonded to water adsorbed on the silicon oxide particles or silanols on the silicon oxide surface. The amount of bonded silanol (Si-OH) on the silicon oxide particle surface is obtained by IR measurement. Specifically, the IR spectrum is normalized at 800 cm⁻¹, and the baseline is matched at 3800 cm⁻¹. The relative value of the bonded Si-OH peak intensity is then calculated from the maximum peak located in the 3300–3700 cm⁻¹ range. If the maximum IR peak intensity of the spherical silicon oxide surface, which originates from bonded silanol groups and is located at 3300~3700 cm⁻¹, is below 0.2, dielectric loss can be reduced. In addition, infrared spectrophotometry (IR) can be performed using, for example, IR Prestige-21 (manufactured by Shimadzu Corporation), which disperses spherical silicon oxide powder in diamond and performs the measurement using the diffusion-reflectance method (measurement conditions: measurement range 400~4000 cm⁻¹, resolution 4 cm⁻¹, cumulative number of times 128). The dilution of diamond powder is defined as [mass dilution rate] = ([sample mass]) / ([diamond mass] + [sample mass]), and let [mass dilution rate] = 85 - 2.5 × [BET specific surface area].

[0033] From the perspective of electrical properties such as dielectric tangent and physical properties such as viscosity of this composition, the spherical silicon oxide should preferably be non-porous particles. Specifically, the oil absorption of the spherical silicon oxide should preferably be less than 100ml / 100g, preferably less than 70ml / 100g, and ideally less than 50ml / 100g.

[0034] The titanium (Ti) contained in this spherical silicon oxide should preferably be in the range of 30 to 1500 ppm, preferably in the range of 100 to 1000 ppm, and even more preferably in the range of 100 to 500 ppm.

[0035] This spherical silicon oxide may further contain other elements. Examples of other elements include Na, K, Mg, Ca, Al, and Fe. The total content of alkali metals and alkaline earth metals among these other elements should preferably be below 2000 ppm, preferably below 1000 ppm, and even better below 200 ppm.

[0036] This spherical silica can also be treated with a silane coupling agent. By treating the surface of this spherical silica with a silane coupling agent, the amount of residual silanol groups on the surface is reduced, the surface is hydrophobic, water adsorption is inhibited and dielectric loss is increased, and the affinity with F polymer is improved, resulting in improved dispersibility and strength of molded products such as polymer layers obtained from this composition. Examples of silane coupling agents include: aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, and organosilazane compounds. Two or more of these can also be used in combination. The amount of silane coupling agent adhering to the surface of the spherical silicon oxide should be such that all the silanol groups present on the surface of the spherical silicon oxide can react. Specifically, relative to 100 parts by mass of the spherical silicon oxide, it should preferably be 0.01 parts by mass or more, preferably 0.05 parts by mass or more, preferably 2 parts by mass or less, and preferably 1 part by mass or less.

[0037] The spherical silicon oxide is preferably obtained by heat treatment of a spherical silicon oxide precursor formed by a wet process. The wet process refers to a method that includes the steps described below: using a liquid as a source of silicon oxide and gelling it to obtain spherical silicon oxide powder as a raw material. Examples of wet methods include spraying, emulsion / gelation, etc.

[0038] The pore volume of the spherical silicon oxide precursor obtained by the wet method should preferably be 0.3~2.2 ml / g. Here, the pore volume is obtained by the BJH method, which is based on nitrogen adsorption using a specific surface area and pore distribution measuring device (e.g., Microtrac BEL's "BELSORP-miniII", Micromeritics' "TriStar II"). The loss on ignition of the silicon oxide precursor obtained by the wet method should be 5.0 to 15.0% by mass. Here, the loss on ignition is calculated according to JIS K0067, as the mass loss after heating and drying 1 g of silicon oxide precursor at 850°C for 0.5 hours.

[0039] In heat treatment, the sintered spherical silicon oxide powder is densified to refine the shell and simultaneously reduce the amount of silanol groups on the surface, thereby lowering the dielectric tangent. The heat treatment temperature should preferably be 700~1600℃. Examples of the aforementioned heat treatment methods include: heat treatment performed by static holding, heat treatment performed by rotary kiln, and heat treatment performed by spray combustion.

[0040] Alternatively, the spherical silica obtained by the method can be surface-treated with a silane coupling agent to react the silanol groups present on the surface of the spherical silica with the silane coupling agent. The silane coupling agent can be any of the aforementioned compounds, or a combination of two or more. The amount of silane coupling agent used should preferably be 0.01 to 5 parts by mass relative to 100 parts by mass of the spherical silicon oxide. Methods for surface treatment using silane coupling agents include, for example, a dry method of spraying the spherical silicon oxide with a silane coupling agent, or a wet method of dispersing the spherical silicon oxide in a solvent and then adding a silane coupling agent to allow it to react.

[0041] The liquid dispersion medium contained in this composition is a liquid that has the function of dissolving, dispersing, or gelling F particles or spherical silicon oxide. This composition is usually in the form of a slurry or gel. In addition, liquid means that the viscosity at 25°C is less than 10 mPa·s. From the viewpoint that the distribution of the spherical silicon oxide in the polymer layer constituting the laminate described later is uniform and that voids are suppressed, the liquid dispersion medium should be degassed.

[0042] The liquid dispersion medium can be water or a non-aqueous dispersion medium. Furthermore, the liquid dispersion medium can be aprotic or protic dispersion medium. Liquid dispersion media are compounds that are liquid at atmospheric pressure and 25°C, such as water, alcohols, amides, ketones and esters. Alcohols include: methanol, ethanol, isopropanol, and diols (ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, etc.). Examples of acetylamines include: N-methyl-2-pyrrolidone, N,N-dimethylmethoxymethylamine, N,N-dimethylacetylamine, N,N-dimethylpropionic acid, 3-methoxy-N,N-dimethylpropionic acid, 3-butoxy-N,N-dimethylpropionic acid, N,N-diethylmethoxymethylamine, trimethylamine hexamethylphosphate, and 1,3-dimethyl-2-imidazolidinedione. 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.

[0043] Two or more liquid dispersion media may be used together. When using two or more, it is best if the dissimilar liquid dispersion media are miscible. The boiling point of a liquid dispersion medium should preferably be in the range of 50~240℃. The content of the liquid dispersion medium in this composition, relative to the total mass of the composition, is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more. The content of the liquid dispersion medium is preferably 80% by mass or less, more preferably 70% by mass or less. Within the aforementioned range, this composition is suitable for processing as a liquid or paste form, and its dispersion stability and coatability are more easily improved.

[0044] The content of F particles in this composition, relative to the total mass of the composition, should preferably be 10% by mass or more, preferably 20% by mass or more. From the viewpoint of the dispersion stability of this composition, the content of F particles, relative to the total mass of the composition, should preferably be 40% by mass or less, preferably 30% by mass or less. The content of the spherical silicon oxide in this composition, relative to the total mass of the composition, should preferably be 10% by mass or more, preferably 20% by mass or more. From the viewpoint of the dispersion stability of this composition, the content of the spherical silicon oxide, relative to the total mass of the composition, should preferably be 60% by mass or less, preferably 50% by mass or less.

[0045] Furthermore, relative to the overall mass of this composition, the content of the spherical silicon oxide is 10-60% by mass, preferably in the range of 20-50% by mass, and the content of F particles is 10-40% by mass, preferably in the range of 10-30% by mass. Moreover, the content of the spherical silicon oxide in this composition is preferably greater than the content of F particles. Within these ranges, it is easy to obtain a composition that suppresses viscosity increase without sacrificing excellent dispersion stability, and it is easy to form polymer layers of any thickness, especially thick polymer layers, from this composition.

[0046] The total content of F particles and spherical silicon oxide in this composition, relative to the overall mass of the composition, should preferably be 20% by mass or more, preferably 50% by mass or more. The total content of F particles and spherical silicon oxide, relative to the overall mass of the composition, should preferably be 95% by mass or less, preferably 75% by mass or less.

[0047] Depending on the requirements, this composition may further contain inorganic fillers different from the spherical silica. Examples of such inorganic fillers, which are different from the spherical silica, include: boron nitride fillers, aluminum nitride fillers, beryllium oxide fillers, silicate fillers (silica fillers, wollastonite fillers, talc fillers), metal oxide fillers (cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.), and magnesium metasilicate (block talc) fillers. These fillers may also be sintered ceramic fillers. The aforementioned inorganic filler may also be surface-treated with a silane coupling agent on at least a portion of its surface. The surface-treated inorganic filler has excellent affinity with F particles, which easily improves the dispersibility of this composition.

[0048] From the perspective of further improving dispersion stability and processability, this composition may further contain surfactants. The surfactants should preferably be nonionic. The hydrophilic portion of a surfactant should preferably have an alkyl group or an alcoholic hydroxyl group. The hydrophobic sites of surfactants should preferably have acetylene, polysiloxane, perfluoroalkyl, or perfluoroolefin groups. In other words, surfactants should preferably be acetylene-based, polysiloxane-based, or fluorine-based surfactants, with polysiloxane-based surfactants being preferred.

[0049] Specific examples of the surfactants mentioned include: the "Ftergent" series (manufactured by NEOS Ltd.), the "Surflon" series (manufactured by AGC Seimi Chemical Ltd.), the "Megafac" series (manufactured by DIC Ltd.), the "UNIDYNE" series (manufactured by DAIKIN Industrial Ltd.), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", "BYK-3456" (manufactured by BYK Japan Ltd.), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), and the "Tergitol" series (manufactured by Dow Chemical Ltd., "Tergitol TMN-100X", etc.). When this composition contains surfactants, the amount should preferably be in the range of 1-15% by mass. At this level, the affinity between components is enhanced, and the dispersion stability and processability of this composition are more easily improved.

[0050] This composition may further include aromatic polymers. Aromatic polymers may be thermoplastic or thermosetting. Aromatic polymers may also be included in this composition in their precursor form. Aromatic polymers may also be included in this composition in particulate form and may be soluble in a liquid dispersion medium. When this composition contains water, the aromatic polymers should preferably be water-soluble.

[0051] Examples of aromatic polymers include: aromatic polyimides, aromatic polyimide precursors (polyacrylic acid or its salts), aromatic polyamide-imides, aromatic polyamide-imide precursors, aromatic polyether-imides, aromatic polyether-imides, aromatic sulfur-based resins, aromatic sulfide-based resins, phenolic resins, aromatic epoxy resins, aromatic polyester resins (liquid crystal aromatic polyesters, etc.), aromatic polyester-imides (liquid crystal aromatic polyester-imides, etc.), aromatic maleic-butenediamides, and polyphenylene ethers. Aromatic polyimide precursors, aromatic polyamide-imides, and aromatic polyamide-imide precursors are preferred. At this point, aromatic polymers readily interact with F polymers, and even the adhesion or UV absorption of molded articles formed from this composition to substrates such as metal foils tends to become excellent. When this composition contains water, it is preferable to use water-soluble aromatic polyamide-imide precursors and water-soluble aromatic polyamide-imide precursors.

[0052] Examples of aromatic polyimide precursors include: polyamides polymerized from tetracarboxylic dianhydrides and diamines in a solvent, or polyamide salts reacted with ammonia or organic amines. Specific examples of aromatic polyimides or their precursors include: the "Neopulim" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), the "SPIXAREA" series (manufactured by SOMAR Corporation), the "Q-PILON" series (manufactured by PIRD Technology Research Institute), the "WINGO" series (manufactured by WINGO TECHNOLOGY Corporation), the "Tomaido" series (manufactured by T&K TOKA Corporation), the "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.), and the "UPIA-AT" series (manufactured by Ube Industries Co., Ltd.).

[0053] Aromatic polyamide-imide or its precursors include: polyamide-imide resins or their precursors obtained by reacting diisocyanate and / or diamine with a tricarboxylic acid anhydride (or tricarboxylic acid chloride) as an acid component. Specific examples of aromatic polyamide imides or their precursors include: "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials Co., Ltd.).

[0054] When this composition further comprises aromatic polymers, their content relative to the total mass of the composition is preferably 0.01% by mass or more, and more than 1% by mass. The content of aromatic polymers is preferably 5% by mass or less, and less than 3% by mass. The content of aromatic polymers in this composition, relative to the content of F polymers in this composition, should preferably be less than 10% by mass or less than 5% by mass. The content of aromatic polymers, relative to the content of F polymers, should preferably be more than 0.1% by mass. When the composition contains an aromatic polymer, the aromatic polymer can function as a dispersant or binder between the spherical silica and the F polymer, easily forming a dense polymer layer, and the spherical silica is easily and highly dispersed in the polymer layer. As long as the content of aromatic polymers is within the aforementioned low range, the electrical properties of the polymer layer are easily excellent.

[0055] In addition to inorganic fillers, surfactants, and aromatic polymers, this composition may further contain additives such as thixotropic agents, viscosity modifiers, defoamers, silane coupling agents, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, surface treatment agents, and flame retardants.

[0056] The viscosity of this composition should preferably be above 10 mPa·s, and above 50 mPa·s is preferred. The viscosity of this composition should preferably be below 10000 mPa·s, below 1000 mPa·s is preferred, and below 500 mPa·s is even better. The viscosity of this composition should preferably be in the range of 50~1000 mPa·s. At this range, due to the excellent coatability of this composition, it is easy to form polymer layers and other molded objects of arbitrary thickness. The thixotropic ratio of this composition should preferably be 1 or higher. A thixotropic ratio of 3 or lower, preferably 2 or lower, is preferable. At this ratio, the composition not only exhibits excellent coatability but also excellent homogeneity, thus easily forming finer polymer layers and other molded products.

[0057] This composition can be manufactured by mixing F particles, spherical silicon oxide, and a liquid dispersion medium. There are no particular limitations on the mixing method as long as it can uniformly mix the F particles, the spherical silicon oxide, the liquid dispersion medium, and other components as required. Examples include: (a) a method of mixing by adding each component at once or sequentially; (b) a method of pre-mixing the F particles and the liquid dispersion medium, and the spherical silicon oxide and the liquid dispersion medium separately, and then further mixing the two mixtures; (c) a method of pre-mixing the F particles and the spherical silicon oxide to form a powder mixture, and then mixing the resulting powder mixture with the liquid dispersion medium. From the viewpoint that the resulting composition is likely to be homogeneous, method (b) or (c) is preferable. Furthermore, when this composition further contains inorganic fillers, surfactants, aromatic polymers, and other components that may be added arbitrarily, it is advisable to pre-add them to the liquid dispersion medium before mixing the liquid dispersion medium, F particles, and the spherical silicon oxide. When this composition contains aromatic polymers, the aromatic polymers can also be mixed with the F particles in the form of a varnish. Solvents constituting the varnish include N-methyl-2-pyrrolidone, cyclohexanone, and toluene.

[0058] Examples of mixing devices used to obtain this composition include: mixing devices with blades (Henschel mixer, pressure kneader, Banbury mixer, planetary mixer, etc.), grinding devices with media (ball mill, grinder, basket mill, sand mill, sand grinder, dyno-mill, disperser, SC mill, spike mill, or agitator mill, etc.), and dispersion devices with other mechanisms (microfluidizer, nanomizer, ultimaizer, ultrasonic homogenizer, dissolver, disperser, high-speed impeller, planetary centrifugal mixer, colloid mill, thin-film rotary high-speed mixer, etc.).

[0059] Furthermore, a preferred method for manufacturing this composition is as follows: F particles, the spherical silicon oxide, and a portion of a liquid dispersion medium are kneaded together to obtain a kneaded compound; then, the remaining liquid dispersion medium is added to the aforementioned kneaded compound and mixed to obtain the composition. The liquid dispersion medium used during kneading and addition can be of the same type or different types. When this composition further includes other components such as inorganic fillers, surfactants, and aromatic polymers, these other components can be mixed during kneading or when the remaining liquid dispersion medium is added to the kneaded compound. When kneading F particles, spherical silicon oxide, and a portion of the liquid dispersion medium beforehand, the mixing methods can be, for example, those described in (a), (b), or (c) above. From the viewpoint that the resulting composition is likely to be homogeneous, method (b) or (c) above is preferable. For kneading, a planetary mixer is recommended. A planetary mixer is a mixing device with two rotating blades that revolve around each other. For adding, a thin-film rotary high-speed mixer is recommended. A thin-film rotary high-speed mixer is a mixing device that causes F particles and liquid dispersion media to spread out in a thin film along the inner wall of a cylindrical mixing tank, while centrifugal force is applied to mix them.

[0060] The kneaded mixture can be in the form of a paste (a paste with a viscosity of 1,000 to 100,000 mPa·s, etc.) or a wet powder (a wet powder (kneaded powder) with a viscosity of 10,000 to 100,000 Pa·s as measured by a capillary rheometer). In addition, the viscosity measured using a capillary rheometer refers to the value measured using a capillary with a length of 10 mm and a radius of 1 mm, a furnace diameter of 9.55 mm, a load cell capacity of 2 t, a temperature of 25 °C, and a shear rate of 1 s⁻¹.

[0061] This composition is used as a coating material to impart insulation, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity. Specifically, this composition can be used in: printed wiring boards, thermal interface materials, power module substrates, coils used in power devices such as motors, automobile engines, heat exchangers, small glass bottles, syringes, ampoules, medical wires, secondary batteries such as lithium-ion batteries, primary batteries such as lithium batteries, free radical batteries, solar cells, fuel cells, lithium-ion capacitors, hybrid capacitors, capacitors, condensers (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive and negative electrodes). Furthermore, this composition is an adhesive used as a bonding agent for bonding components. Specifically, this composition can be used for: bonding ceramic components, bonding metal components, bonding IC chips or electronic components such as resistors and capacitors in the substrate of semiconductor elements or module components, bonding circuit boards and heat sinks, and bonding LED chips to substrates.

[0062] In particular, this composition is intended for use as a printed wiring board, and more specifically, as a material for forming a polymer layer in a copper foil with a polymer-coated layer, wherein the copper foil with the polymer-coated layer has a polymer layer formed by this composition on its surface. As shown in Table 1 below, spherical silicon oxide itself has excellent electrical properties (especially dielectric tangent) and low linear expansion, but these properties are difficult to fully exhibit in the polymer layer of the copper foil with the polymer-coated layer. By using this composition and through the above-described mechanism, a copper foil with a polymer-coated layer can be easily obtained, which possesses the properties of spherical silicon oxide and F polymer.

[0063] [Table 1]

[0064] This composition is suitable for use as a composition formed by applying it to at least one surface of a substrate and heating it, thereby forming a polymer layer comprising the F polymer and the spherical silicon oxide (hereinafter also referred to as the "F layer"). For example, by applying this composition to the surface of a substrate to form a liquid film (wet film) composed of this composition, and then heating to remove the liquid dispersion medium from the liquid film, a polymer layer containing polymer F and this spherical silicon oxide can be formed on the aforementioned substrate surface. The obtained polymer layer, F polymer, can be further sintered. By heating and sintering the F polymer, a laminate having a substrate layer and a polymer layer can be manufactured, wherein the polymer layer is located on the surface of the substrate layer and includes the sintered F polymer and the spherical silicon oxide. In addition, heating for removing the liquid medium and heating for sintering the F polymer can be performed continuously.

[0065] Examples of substrates include: metal substrates such as copper, nickel, aluminum, titanium, and their alloys; heat-resistant resin films made of heat-resistant resins such as tetrafluoroethylene polymers, polyimide, polyarylate, polyurethane, polyallyl sulfone, polyamide, polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamideimide, liquid crystal polyester, and liquid crystal polyesteramide; prepregs that are precursors to fiber-reinforced resin substrates; ceramic substrates such as silicon carbide, aluminum nitride, and silicon nitride; and glass substrates. The shape of the substrate can be planar, curved, or uneven. Furthermore, the shape of the substrate can be any of the following: foil, plate, film, or fibrous.

[0066] The average roughness of the substrate surface at ten points should preferably be less than 0.1 μm, and less than 0.05 μm is preferred. The aforementioned average roughness at ten points should preferably be 0.001 μm or more. Even with the aforementioned unroughened substrate, a polymer layer with excellent uniformity can still be obtained according to this method, thus a laminate with excellent peel strength can be obtained. Furthermore, the average roughness of the substrate surface at ten points is the value specified in Appendix JA of JIS B 0601:2013. The thickness of the substrate is preferably 2~100μm. When the substrate is a metal foil, the thickness is preferably 1~35μm. Alternatively, the substrate may be an extremely thin copper foil (2~5μm thick) deposited on a carrier copper foil with a release layer. When the substrate is a polyimide film, the thickness is preferably 10~50μm.

[0067] To further improve the low linear expansion and adhesion of the laminate, the outermost surface of the substrate can also be further surface-treated. Surface treatment methods include: annealing, corona treatment, plasma treatment, ozone treatment, excimer laser treatment, and silane coupling agent treatment. The annealing conditions should be a temperature of 120~180℃, a pressure of 0.005~0.015MPa, and a time of 30~120 minutes. Gases used in plasma processing include: oxygen, nitrogen, rare gases (such as argon), hydrogen, ammonia, and vinyl acetate. Two or more of these gases may also be used in combination.

[0068] Any method for applying this composition to the surface of a substrate may be any method that can form a stable liquid film (wet film) composed of this composition on the surface of the substrate. Examples include coating, droplet ejection, and immersion methods, with coating being preferred. As long as the coating method is used, a liquid film can be efficiently formed on the surface of a metal substrate using simple equipment. Coating methods include: spraying, roller coating, spin coating, gravure coating, micro-gravure coating, gravure plate coating, doctor blade coating, contact coating, bar coating, mold coating, fountain Meyer bar coating, and slot die coating.

[0069] The F layer is preferably formed by further heating to a high temperature to calcine the polymer after removing the liquid dispersion medium from the aforementioned liquid film (wet film) through heating. The removal temperature of the liquid dispersion medium should be as low as possible, preferably 50-150°C lower than the boiling point of the liquid dispersion medium. For example, when using N-methyl-2-pyrrolidone with a boiling point of about 200°C, heating should be below 150°C, preferably 100-120°C. Air can also be blown in during the removal of the liquid dispersion medium to promote its removal by air drying. In this case, the liquid dispersion medium does not necessarily need to be completely removed during heating; it is sufficient to remove it until the layer formed by the accumulation of F particles can maintain a self-supporting film.

[0070] After removing the liquid dispersion medium, the polymer layer on the substrate should be heated to the temperature range for firing the polymer F to form an F layer containing the polymer F. For example, the polymer F should be fired in the range of 300 to 400°C. The F layer should preferably contain the sintered polymer F. The heating devices used in each heating process can be ovens or ventilated drying ovens. The heat source in the device can be a contact heat source (hot air, hot plate, etc.) or a non-contact heat source (infrared rays, etc.). Each heating element can be performed under normal pressure or under reduced pressure. The gas environment during each heating process can be either an air environment or an inactive gas environment (helium, neon, argon, nitrogen, etc.). The F layer is formed by applying the composition to the surface of a substrate and heating it. To obtain a thick F layer, the application and heating of the composition can be repeated multiple times to form the F layer. For example, the composition can be applied to the surface of a substrate and heated to form the F layer, and then the composition can be further applied to the surface of the aforementioned F layer and heated to form a second F layer. Furthermore, during the stage where the composition is applied to the surface of a substrate and heated to remove the liquid dispersion medium, the composition can also be further applied to its surface and heated to form the F layer.

[0071] The thickness of the F layer should preferably be 50 μm or more, and 100 μm or more is preferred. The thickness of the F layer should preferably be less than 1000 μm. Even with a relatively thick F layer, a polymer layer with excellent dispersibility of the spherical silicon oxide can still be obtained through the above-mentioned mechanism.

[0072] The peel strength between layer F and the substrate layer should preferably be above 10 N / cm, and above 15 N / cm is preferable. The peel strength mentioned above should preferably be below 100 N / cm. Furthermore, the tensile strength of layer F should preferably be above 5 MPa, with 10 MPa being more preferable. The aforementioned tensile strength should preferably be below 100 MPa. By using this composition, a laminate with excellent peel strength between the F layer and the substrate layer and excellent tensile strength of the F layer can be easily formed without compromising the physical properties of the F polymer in the F layer.

[0073] This composition can be applied to only one surface of the substrate, or it can be applied to both surfaces of the substrate. In the former case, a laminate having a substrate layer and an F layer located on a single surface of the substrate layer can be obtained; in the latter case, a laminate having a substrate layer and an F layer located on both surfaces of the substrate layer can be obtained. Preferred examples of laminates include: a metal-clad laminate having a metal foil and an F layer located on at least one surface of the metal foil; and a multilayer film having a polyimide film and F layers located on both surfaces of the polyimide film. These laminates are suitable as printed circuit board materials due to their excellent electrical properties and other physical properties, and can be used in the manufacture of flexible or rigid printed circuit boards.

[0074] Other substrates can also be further laminated on the outermost surface of the laminate. Other substrates include: metal substrates, heat-resistant resin films, prepregs that are precursors to fiber-reinforced resin boards, laminates having heat-resistant resin film layers, and laminates having prepreg layers. Metal substrates include the aforementioned metal substrates. The heat-resistant resin film is a film containing one or more heat-resistant resins; the heat-resistant resin includes the aforementioned resins. Furthermore, the substrate can be removed from the laminate. At this point, a film composed of individual F layers can be obtained.

[0075] Laminated bodies, laminates of laminates with other substrates, and film systems composed of F layers are used as antenna components, printed circuit boards, aircraft parts, automotive parts, sporting goods, food industry products, coatings, cosmetics, etc. Specifically, it can also be used for the following examples: wire sheathing materials (aircraft wires, etc.), enameled wire sheathing materials used in motors of electric vehicles, electrical insulation tape, oil drilling insulation tape, materials for printed circuit boards, separation membranes (precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas permeation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), and photocopying drums. Roll), housings for furniture, automotive dashboards, and home appliances; sliding components (load bearings, sliding shafts, valves, bearings, bushings, seals, thrust washers, wear parts, pistons, slide switches, gears, cams, belt conveyors, food conveyor belts, etc.); wear pads, wear strips, tubular lights, test sockets, wafer conductors, wear parts for centrifugal pumps, hydrocarbon / pharmaceutical and water supply pumps, tools (shovels, files, awls, saws, etc.), boilers, hoppers, pipe fittings, ovens, baking molds, chutes, molds, toilets, container coverings, power components, transistors, thyristors, commutators, transformers, power MOSFETs. FETs, CPUs, heat sinks, metal heat sinks, blades of windmills or wind power generation equipment or aircraft, heat dissipation substrates for automobiles, and heat dissipation components for wireless communication devices (e.g., the wireless communication devices described in International Publication No. 2020 / 008691 and International Publication No. 2020 / 031419).

[0076] The present invention has been described above regarding the composition, the method of manufacturing the composition, the method of manufacturing a laminate having a polymer layer formed from the composition, and the laminate. However, the present invention is not limited to the above-described embodiments. For example, in the above-described embodiments, any other components may be added to the composition and the aforementioned laminate, or they may be replaced with any component that performs the same function. Furthermore, in the above-described embodiments, the manufacturing methods of the composition and the aforementioned laminate may be added with any other steps, or they may be replaced with any step that produces the same effect. Example

[0077] The present invention will now be described in detail with reference to embodiments, but the present invention is not limited thereto. 1. Preparation of each ingredient [F particle] F particle 1: Particles composed of F polymer 1 (D50: 2.1 μm), which contains TFE units, NAH units and PPVE units in sequence at 97.9 mol%, 0.1 mol%, and 2.0 mol%, has a fluorine content of 76% by mass, and has 1000 carbonyl groups relative to 1 × 10⁶ carbon atoms per main chain. F particle 2: Particles composed of F polymer 2 (D50: 2.5 μm), which contains TFE units and PPVE units in sequence at 97.5 mol% and 2.5 mol%, has a fluorine content of 76% by mass, and contains less than 25 carbonyl groups relative to 1 × 10 6 carbons per main chain. [Spherical silicon oxide] Spherical silicon oxide 1: Spherical silicon oxide powder (median particle size d=3μm, specific surface area 1.3m² / g) was obtained by heating silicon oxide powder (manufactured by AGC Si-Tech Corporation "H-31", median particle size d=3.5μm, Ti content 300ppm) at 1300℃ for 1 hour. Spherical silicon oxide 2: Spherical silicon oxide manufactured from raw silicon oxide using the VMC method (Admatechs "SC-04", median particle size d=1.5μm, specific surface area 4.5m² / g, Ti content 28ppm). Spherical silicon oxide 3: Spherical silicon oxide with median particle size d=0.6μm and specific surface area of ​​6.2m² / g. [Liquid Dispersion Medium] NMP: N-methylpyrrolidone [Surfactants] Surfactant 1: Nonionic surfactant (Ftergent 710FL)

[0078] 2. Examples of manufacturing liquid components [Example 1] A paste-like mixture was obtained by kneading 25 parts by mass of F particles 1, 50 parts by mass of spherical silicon oxide 1, 5 parts by mass of surfactant 1, and 20 parts by mass of NMP using a rotary mixer (Defoaming Rentaro, THINKY Corporation). Then, 55 parts by mass of NMP were added to the kneaded mixture and stirred at 2000 rpm for 5 minutes to obtain liquid composition 1. The viscosity of the resulting liquid composition 1 was less than 100 mPa·s. [Example 2] Except that 50 parts by mass of spherical silicon oxide 2 were used to replace 50 parts by mass of spherical silicon oxide 1, liquid composition 2 was obtained in the same manner as in Example 1. The viscosity of the resulting liquid composition 2 was greater than 100 mPa·s. [Example 3] Except that 50 parts by mass of spherical silicon oxide 3 were used to replace 50 parts by mass of spherical silicon oxide 1, liquid composition 3 was obtained in the same manner as in Example 1. The viscosity of the resulting liquid composition 3 was greater than 100 mPa·s. [Example 4] Except that 25 parts by mass of F particles 2 were used to replace 25 parts by mass of F particles 1, liquid composition 4 was obtained in the same manner as in Example 1. The viscosity of the obtained liquid composition 4 is less than 100 mPa·s.

[0079] 3. Examples of manufacturing laminated bodies [Example 4] A wet film is formed by coating a liquid composition 1 onto the surface of a copper foil (thickness: 18 μm). Next, the metal foil with the wet film is passed through a drying oven at 120°C for 5 minutes to dry it and obtain a dry film. Then, the dry film is heated at 380°C for 3 minutes in a nitrogen oven. This produces a polymer-coated copper foil, i.e., a laminate 1, which has a copper foil and a polymer layer (thickness: 50 μm) as a forming element. The polymer layer is located on the surface of the copper foil and contains F polymer and spherical silicon oxide 1. [Examples 5~7] Except for changing the liquid composition used, the laminate 2 was obtained from liquid composition 2 (Example 5), the laminate 3 was obtained from liquid composition 3 (Example 6), and the laminate 4 was obtained from liquid composition 4 (Example 7) in the same manner as in Example 4.

[0080] 4. Evaluation 4-1. Dispersion stability of liquid components After each liquid component was allowed to stand at 25°C for 30 days, its dispersion was visually observed, and its long-term dispersion stability was evaluated according to the following criteria. The results are shown in Table 2. <Evaluation Criteria> 〇: No thickening and no component sedimentation confirmed. △: Although layer separation can be confirmed, it can be easily redispersed, and no thickening effect after redispersibility has been confirmed. ×: This can confirm thickening or component sedimentation.

[0081] [Table 2]

[0082] 4-2. Evaluation Example of Layered Bodies The smoothness of the polymer layer surfaces in each laminate, from highest to lowest, was determined by visual inspection: laminate 1, laminate 4, laminate 3, and laminate 2. Furthermore, the copper foil of each laminate was removed by etching with ferric chloride aqueous solution to obtain a separate polymer layer. Four 180mm square test pieces were cut out, and the coefficient of linear expansion was measured according to the method for measuring the coefficient of linear expansion specified in JIS C 6471:1995. The coefficients of linear expansion from low to high were polymer layers of laminate 1, polymer layers of laminate 4, polymer layers of laminate 3, and polymer layers of laminate 2. Furthermore, the dielectric tangent of each polymer layer was measured using SPDR (Split Post Dielectric Resonator, measurement frequency: 10 GHz), and the dielectric tangent of the polymer layer of laminate 1 was the lowest.

[0083] 4. Examples of membrane manufacturing [Example 8] Except that the thickness of the polymer layer used as the molded product is 150 μm, copper foils with polymer layers are manufactured from each liquid component in the same manner as in Example 4, and then the copper foils are further etched away to manufacture individual films. The surface smoothness of the resulting films is the highest for the film formed from liquid component 1.

[0084] Industrial availability According to the present invention, a liquid composition with excellent uniformity and dispersion stability and low viscosity can be obtained. The laminate obtained from this liquid composition has excellent electrical properties such as low dielectric tangent, and is suitable for use as a material for printed wiring boards, for example. Furthermore, all contents of the specification, scope of application and abstract of Japanese Patent Application No. 2021-193907, filed on November 30, 2021, are incorporated herein as disclosure in this specification.

Claims

1. A liquid composition comprising: tetrafluoroethylene-based polymer particles; spherical silicon oxide with a median particle size d (μm) greater than 0.6 μm and less than 20 μm, and the product of the median particle size d and the specific surface area A (m² / g), d×A, is 2.7~5.0 μm·m² / g; and a liquid dispersion medium; wherein the specific surface area A is obtained by the BET method, which is based on a nitrogen adsorption method using a specific surface area·pore distribution measuring device.

2. The liquid composition of claim 1, wherein the aforementioned tetrafluoroethylene polymer is a thermomeltable tetrafluoroethylene polymer.

3. The liquid composition of claim 1 or 2, wherein the aforementioned tetrafluoroethylene polymer is a tetrafluoroethylene polymer having an oxygen-containing polar group, comprising units mainly composed of perfluorinated (alkyl vinyl ethers).

4. The liquid composition of claim 1 or 2, wherein the specific surface area of ​​the aforementioned spherical silicon oxide is 0.2 to 2.0 m² / g.

5. The liquid composition of claim 1 or 2, wherein the maximum IR peak intensity of the aforementioned spherical silicon oxide surface, which originates from bonded silanol groups and is located at 3300~3700cm-1, is less than 0.

2.

6. The liquid composition of claim 1 or 2, wherein, relative to the total mass of the liquid composition, the content of the aforementioned spherical silicon oxide is 10 to 60% by mass, the content of the aforementioned tetrafluoroethylene polymer particles is 10 to 40% by mass, and the content of the aforementioned liquid dispersion medium is 5% by mass or more.

7. The liquid composition of claim 1 or 2, wherein the content of the aforementioned spherical silicon oxide is greater than the content of the aforementioned tetrafluoroethylene polymer particles.

8. The liquid composition of claim 1 or 2 further comprises a surfactant.

9. The liquid composition of claim 1 or 2 further comprises an aromatic polymer.

10. The liquid composition of claim 1 or 2 further comprises an inorganic filler different from the aforementioned spherical silicon oxide.

11. The liquid composition of claim 1 or 2 has a viscosity of 50 to 1000 mPa·s.

12. A method for manufacturing a liquid composition as claimed in any one of claims 1 to 11, comprising mixing the aforementioned tetrafluoroethylene polymer particles, the aforementioned spherical silicon oxide and the aforementioned liquid dispersion medium to obtain the liquid composition.

13. A method for manufacturing a liquid composition, comprising manufacturing a liquid composition as claimed in any one of claims 1 to 11, the method comprising: kneading a composition containing the aforementioned tetrafluoroethylene polymer particles, the aforementioned spherical silicon oxide and a portion of the aforementioned liquid dispersion medium to obtain a kneaded compound, and further adding the remaining aforementioned liquid dispersion medium to the kneaded compound and mixing to obtain the aforementioned liquid composition.

14. A method for manufacturing a laminate, comprising applying a liquid composition as claimed in any one of claims 1 to 11 to a substrate surface to form a liquid film composed of the liquid composition, then heating to remove the liquid dispersion medium from the liquid film, and forming a polymer layer comprising the aforementioned tetrafluoroethylene polymer and the aforementioned spherical silicon oxide on the substrate surface.

15. A laminate comprising: a substrate; and a polymer layer disposed on the surface of the substrate and formed of a liquid composition as claimed in any one of claims 1 to 11, comprising a tetrafluoroethylene-based polymer and the aforementioned spherical silicon oxide.