WO2023100739A1

WO2023100739A1 - Liquid composition, laminate, and production methods therefor

Info

Publication number: WO2023100739A1
Application number: PCT/JP2022/043343
Authority: WO
Inventors: 創太結城; 渉笠井
Original assignee: Ａｇｃ株式会社
Priority date: 2021-11-30
Filing date: 2022-11-24
Publication date: 2023-06-08
Also published as: TW202323429A

Abstract

Provided are: a liquid composition which has excellent uniformity and dispersion stability and has a low viscosity; a method for producing said liquid composition; a method for producing a laminate which is obtained from said composition and has a polymer layer having excellent adhesiveness to a substrate, thermal conductivity, heat resistance, and electrical characteristics; and said laminate.　The liquid composition contains: particles of a tetrafluoroethylene-based polymer; spherical silica which has a median diameter d (μm) of 0.6-20 μm (exclusive of 0.6) and a product d×A of the median diameter d and a specific surface area A (m2/g) of 2.7-5.0 μm∙m2/g; and a liquid dispersion medium.

Description

Liquid composition, laminate and method for producing the same

The present invention relates to a liquid composition containing a tetrafluoroethylene-based polymer and silica, a method for producing the same, a laminate having a polymer layer formed from the liquid composition, and a method for producing the same.

In recent years, in order to respond to the high speed and high frequency of mobile communication devices such as mobile phones, materials with high thermal conductivity, low coefficient of linear expansion, low dielectric constant and low dielectric loss tangent are required for printed circuit boards of communication devices. A tetrafluoroethylene-based polymer, which has a low dielectric constant and a low dielectric loss tangent, has attracted attention.
Various studies have been made to obtain a material containing a tetrafluoroethylene-based polymer and having more excellent physical properties. For example, Patent Document 1 describes a liquid composition containing a tetrafluoroethylene-based polymer and specific silica particles. Laminates are disclosed that are formed by applying to materials. Patent Document 2 describes that a non-aqueous dispersion containing polytetrafluoroethylene, fine ceramic particles, and a specific fluorine-based additive is added to various resin materials for use.

Japanese Patent Application Laid-Open No. 2019-183005 JP 2016-194017 A

A tetrafluoroethylene-based polymer has a low surface tension and low affinity with other components such as inorganic particles. Therefore, in a molded article formed from a composition containing a tetrafluoroethylene-based polymer and inorganic particles, the dispersibility of the inorganic particles may be insufficient, and the physical properties of each component may not be fully exhibited.
In the liquid composition described in Patent Document 1, from the viewpoint of exhibiting the effect of suppressing linear expansion of the obtained molding with a smaller amount of silica added, silica particles having a specific surface area of 6.5 m ² /g or more, preferably selected mesoporous silica particles, microporous silica particles, hollow silica particles, and the like. In other words, there is still room for improvement from the viewpoint of enhancing the silica-based properties by increasing the amount of silica added.
The non-aqueous dispersion described in Patent Document 2 can improve the uniformity and dispersion stability of the composition by increasing the type of fine-particle ceramics as inorganic particles, increasing the amount of fine-particle ceramics added, or further blending other components. It is difficult to obtain a molded article such as a polymer layer having sufficient properties.

The present inventors have found that by using tetrafluoroethylene-based polymer particles and specific spherical silica, it is possible to obtain a liquid composition that is excellent in uniformity and dispersion stability, and in which thickening is suppressed. Further, from such a liquid composition, a thick polymer layer having excellent electrical properties such as adhesion to a substrate, thermal conductivity, heat resistance, and dielectric loss tangent can be formed, and a laminate having the polymer layer is a printed wiring board. The present invention has been completed by learning that it is useful as a material such as
An object of the present invention is to provide a liquid composition that is excellent in uniformity and dispersion stability and has low viscosity, a method for producing the liquid composition, a method for producing a laminate having a polymer layer obtained from the composition, and the laminate It is the provision of the body.

The present invention has the following aspects.
[1] Particles of a tetrafluoroethylene-based polymer having a median diameter d (μm) of more than 0.6 μm and not more than 20 μm, and a product d×A of the median diameter d and the specific surface area A (m ² /g) of 2.7 to A liquid composition comprising 5.0 μm·m ² /g spherical silica and a liquid dispersion medium.
[2] The liquid composition of [1], wherein the tetrafluoroethylene-based polymer is a heat-melting tetrafluoroethylene-based polymer.
[3] The liquid composition of [1] or [2], wherein the tetrafluoroethylene-based polymer contains units based on perfluoro(alkyl vinyl ether) and has an oxygen-containing polar group.
[4] The liquid composition according to any one of [1] to [3], wherein the spherical silica has a specific surface area of 0.2 to 2.0 m ² /g.
[5] The liquid composition according to any one of [1] to [4], wherein the maximum IR peak intensity at 3300 to 3700 cm ⁻¹ derived from bound silanol groups on the surface of the spherical silica is 0.2 or less.

[6] The content of the spherical silica is 10 to 60% by mass, and the content of the tetrafluoroethylene-based polymer particles is 10 to 40% by mass, relative to the total mass of the liquid composition, and The liquid composition according to any one of [1] to [5], wherein the content of the liquid dispersion medium is 5% by mass or more.
[7] The liquid composition according to any one of [1] to [6], wherein the content of the spherical silica is greater than the content of the tetrafluoroethylene-based polymer particles.
[8] The liquid composition of any one of [1] to [7], further comprising a surfactant.
[9] The liquid composition of any one of [1] to [8], further comprising an aromatic polymer.
[10] The liquid composition according to any one of [1] to [9], further comprising an inorganic filler different from the spherical silica.
[11] The liquid composition of any one of [1] to [10], which has a viscosity of 50 to 1000 mPa·s.

[12] The method for producing a liquid composition according to any one of [1] to [11], wherein the tetrafluoroethylene-based polymer particles, the spherical silica, and the liquid dispersion medium are mixed to obtain a liquid composition.
[13] A method for producing the liquid composition according to any one of [1] to [11],
A composition containing the particles of the tetrafluoroethylene-based polymer, the spherical silica, and a part of the liquid dispersion medium is kneaded to obtain a kneaded material, and the remaining liquid dispersion medium is added to the kneaded material. and mixing to obtain the liquid composition.
[14] Applying the liquid composition according to any one of [1] to [11] to the surface of a substrate to form a liquid coating composed of the liquid composition, and then removing the liquid dispersion medium from the liquid coating by heating. to form a polymer layer containing the tetrafluoroethylene-based polymer and the spherical silica on the surface of the substrate.
[15] A substrate, and a polymer layer provided on the surface of the substrate and containing a tetrafluoroethylene-based polymer formed from the liquid composition according to any one of [1] to [11] and the spherical silica. , laminate.

According to the present invention, a liquid composition that is excellent in uniformity and dispersion stability and has low viscosity, a method for producing the liquid composition, and adhesiveness to a substrate, thermal conductivity, and heat resistance obtained from the composition A method for producing a laminate having a polymer layer with excellent physical properties and electrical properties, and the laminate are provided.

The following terms have the following meanings.
The "melting temperature of a polymer" is the temperature corresponding to the maximum melting peak measured by differential scanning calorimetry (DSC).
A "glass transition point of a polymer" is a value measured by analyzing a polymer by a dynamic viscoelasticity measurement (DMA) method.
"Average particle size of tetrafluoroethylene-based polymer particles" is the volume-based cumulative 50% diameter of the particle size obtained by measuring the particle size of such particles by a laser diffraction/scattering method (hereinafter also referred to as "D50" ). That is, the particle size distribution of particles is measured by a laser diffraction/scattering method, and a cumulative curve is obtained with the total volume of the group of particles being 100%.
The "specific surface area of particles" is a value measured by gas adsorption (constant volume method) BET multipoint method.
“Viscosity” is a value measured for a dispersion using a Brookfield viscometer at room temperature (25° C.) and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average value of the 3 measurements is taken.
The “thixotropic ratio” is calculated by dividing the viscosity η ₁ obtained by measuring the liquid composition at a rotation speed of 30 rpm by the viscosity η ₂ obtained by measuring the rotation speed at 60 rpm. is the value (η ₁ /η ₂ ).
A "unit based on a monomer" means an atomic group based on one molecule of the monomer formed by polymerization of the monomer. The units may be units directly formed by a polymerization reaction, or may be units in which some of said units have been converted to another structure by treatment of the polymer. Hereinafter, units based on monomer a are also simply referred to as "monomer a units".

The liquid composition of the present invention (hereinafter also referred to as "this composition") comprises particles (hereinafter also referred to as "F particles") of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer"). , a spherical silica having a median diameter d (μm) of more than 0.6 μm and 20 μm or less and a product d×A of the median diameter d and the specific surface area A (m ² /g) of 2.7 to 5.0 μm·m ² /g (hereinafter also referred to as "the present spherical silica") and a liquid dispersion medium.
The composition has excellent uniformity and dispersion stability and low viscosity. In addition, the present composition provides a thick polymer layer having excellent electrical properties such as adhesion to substrates, thermal conductivity, heat resistance, and low dielectric loss tangent. A laminate having such a polymer layer is useful as a material for printed wiring boards, etc., having adhesiveness, thermal conductivity and electrical properties.
Although the reason why the properties of the present composition are exhibited is not necessarily clear, it is presumed, for example, as follows.

The F polymer has a low surface energy and its particles tend to agglomerate. In addition, the F polymer has a low affinity with inorganic particles such as silica, and the inorganic particles tend to form aggregates in the polymer layer containing the F polymer and the inorganic particles. Such a tendency tends to become remarkable when the content of inorganic particles is high.
In the present composition, spherical silica (present spherical silica) having a median diameter d within the specific range and a product d×A of the median diameter d and the specific surface area A within the specific range is used. This not only suppresses the aggregation of silica particles in the present composition, but also adjusts the wettability between the silica and the liquid dispersion medium, and relatively increases the affinity between the spherical silica and the F polymer. Conceivable. Since this promotes a high degree of interaction between the F particles and the present spherical silica, the present composition is considered to be excellent in physical properties such as dispersion stability and low viscosity.
In addition, in the present composition in which both particles are highly interacted, self-coagulation of the F particles and the present spherical silica is likely to be promoted, in other words, a pseudo coalescence of the F particles and the spherical silica. It is also presumed that the formation of adhering particles is likely to be facilitated. It is considered that this enhances the uniformity of the present composition, and thus the present composition is excellent in physical properties such as dispersion stability and low viscosity.

In addition, if the present composition has excellent physical properties such as dispersion stability and low viscosity, in which both particles are highly interacted, spherical silica will be present even when it is processed into a molded product or in the state of the molded product after processing. It is difficult to powder off, and the spherical silica can be highly dispersed even in the molded product. As a result, a molded product with excellent electrical properties such as adhesiveness to substrates, thermal conductivity, heat resistance, and low dielectric loss tangent, which originally possessed the physical properties of silica and F-polymer, was developed. It is believed that it could have been easily formed from the composition.

The F polymer in the present composition is a polymer containing units based on tetrafluoroethylene (TFE) (TFE units). The F polymer may be hot melt or non-hot melt. In the composition, it is preferred to use a hot-melt F polymer.
The hot-melt polymer is a melt-fluid polymer that has a melt flow rate of 1 to 1000 g/10 minutes at a temperature that is 20°C or more higher than the melting temperature of the polymer under a load of 49 N. means
Two or more types of F polymers may be used.

The melting temperature of the hot-melt F polymer is preferably 200° C. or higher, more preferably 260° C. or higher. The melting temperature of the F polymer is preferably 325° C. or lower, more preferably 320° C. or lower. In such a case, a molded article formed from the present composition tends to have excellent heat resistance.
The fluorine content in the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass. According to this method, due to the mechanism of action described above, it is easy to obtain a polymer layer in which the present spherical silica is excellent in dispersibility even when using the F polymer, which has a high fluorine content and a low affinity for inorganic particles.
The glass transition point of 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.

Examples of F polymers include polytetrafluoroethylene (PTFE), polymers containing TFE units and ethylene units, polymers containing TFE units and propylene units, and units based on TFE units and perfluoro(alkyl vinyl ether) (PAVE) (PAVE units). polymers containing TFE units (PFA), polymers containing TFE units and hexafluoropropene units (FEP), polymers containing TFE units and units based on fluoroalkylethylene, and polymers containing TFE units and chlorotrifluoroethylene units. PTFE may be non-heat-fusible PTFE or heat-fusible PTFE.
As the F polymer, PFA and FEP are preferred, and PFA is more preferred. These polymers may also contain units based on other comonomers.
PAVE is preferably CF ₂ =CFOCF ₃ , CF ₂ =CFOCF ₂ CF ₃ and CF ₂ =CFOCF ₂ CF ₂ CF ₃ (hereinafter also referred to as PPVE), more preferably PPVE.

The F polymer preferably has oxygen-containing polar groups. When the F polymer has an oxygen-containing polar group, the affinity between the F particles and the present spherical silica tends to increase, and the present spherical silica tends to disperse well in the polymer layer. In addition, when the composition is heated, cross-linking of the F polymer is likely to be formed, and it is believed that a polymer layer having excellent mechanical properties is likely to be obtained. In particular, the use of such an F-polymer tends to highly exhibit the above-described mechanism of action, particularly the effect of self-coagulation.
The oxygen-containing polar group may be contained in a unit based on a monomer in the F polymer, or may be contained in a terminal group of the main chain of the F polymer. As the latter mode, F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, chain transfer agent, etc., F polymer having an oxygen-containing polar group obtained by plasma treatment or ionizing radiation treatment of F polymer polymers.

When the F polymer has an oxygen-containing polar group, the number of oxygen-containing polar groups in the F polymer is preferably 100 to 10,000, more preferably 500 to 5,000 per 1×10 ⁶ carbon atoms in the main chain. preferable.
As the oxygen-containing polar group, a hydroxyl group-containing group, a carbonyl group-containing group and a phosphono group-containing group are preferable, and from the viewpoint of dispersibility of the present spherical silica in the polymer layer, a hydroxyl group-containing group and a carbonyl group-containing group are more preferable, and a carbonyl group. Containing groups are more preferred.

The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH, -C(CF ₃ ) ₂ OH and 1,2-glycol group (-CH(OH)CH ₂ OH). preferable.
A carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and examples of the carbonyl group-containing group include a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, and a carbamate group (--OC(O)NH ₂ ), acid anhydride residues (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.) and carbonate groups (-OC(O)O-) are preferred. , acid anhydride residues are more preferred.
The carbonyl group-containing group may be contained in a monomer unit in the F polymer, or may be contained in a terminal group of the main chain of the polymer. The latter embodiment includes an F polymer having a carbonyl group-containing group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like.
When the F polymer has a carbonyl group-containing group, the number of carbonyl group-containing groups in the F polymer is preferably 100 to 10000, more preferably 500 to 5000, more preferably 800 per 1 × 10 ⁶ carbon atoms in the main chain. ~1500 is more preferred. In this case, the affinity between the F polymer and the present spherical silica is likely to be improved.
The number of carbonyl group-containing groups in the F polymer can be quantified by the composition of the polymer or the method described in WO2020/145133.

As the F polymer, a polymer containing TFE units and PAVE units and having an oxygen-containing polar group is preferable, and a polymer containing TFE units and PAVE units and having a carbonyl group-containing group or a hydroxyl group-containing group is more preferable. Further preferred are polymers comprising units and units based on monomers having carbonyl group-containing groups. The F polymer contains 90 to 99 mol% of TFE units, 0.5 to 9.97 mol% of PAVE units, and 0.01 to 3 units based on the monomer having the carbonyl group-containing group, based on the total units. mol %, respectively, is particularly preferred.
As the monomer having a carbonyl group-containing group, itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH") are preferable.
Specific examples of such polymers include those described in WO2018/16644.
The particles of these F polymers not only have excellent dispersion stability, but also tend to be densely and homogeneously distributed in a molded article (polymer layer, etc.) obtained from the present composition. Furthermore, it is easy to form microspherulites in the molding, and the adhesiveness with other components including the present spherical silica is easy to increase. As a result, it is easier to obtain a molding excellent in various physical properties such as electrical properties.

In the present composition, the D50 of the F particles is preferably 25 µm or less, more preferably 10 µm or less, and more preferably 8 µm or less. D50 of the F particles is preferably 0.1 μm or more, more preferably more than 0.3 μm, and even more preferably 1 μm or more. In this case, the suppression of particle aggregation and the interaction between the F particles and the present spherical silica are highly balanced, and the dispersion stability of the present composition tends to be improved. In addition, the present spherical silica tends to be highly dispersed in the polymer layer.

The bulk density of F particles is preferably 0.15 g/m ² or more. The bulk density of the F particles is preferably 0.50 g/m ² or less.
Further, the specific surface area of the F particles is preferably 25 m ² /g or less, more preferably 8 m ² /g or less, and even more preferably 5 m ² /g or less. The specific surface area of the F particles is preferably 1 m ² /g or more. In this case, aggregation of particles is highly suppressed, and the interaction between the F particles and the present spherical silica is likely to be improved.

Two or more kinds of F particles may be used. When two types of F particles are used, the F particles preferably contain heat-melting F polymer particles and non-heat-melting F polymer particles, and the F polymer having a melting temperature of 200 to 320° C. (preferably contains the TFE units and PAVE units described above, and more preferably contains particles of a polymer having an oxygen-containing polar group) and particles of non-thermally fusible PTFE. Further, it is more preferable that the content of the latter particles is higher than the content of the former particles.
In this case, the F polymer is moderately fibrillated while maintaining physical properties, and the F particles are easily carried in the molded product formed from the present composition, and the strength of the molded product is likely to be further improved.
The ratio of the former particles to the total of the former particles and the latter particles is preferably 50% by mass or less, more preferably 25% by mass or less. Moreover, the ratio in this case is preferably 0.1% by mass or more, more preferably 1% by mass or more.
The composition of the present invention not only tends to be excellent in dispersion stability, uniformity and handleability, but also facilitates the formation of an adhesive molding having excellent physical properties based on non-heat-melting PTFE.
In this case, the D50 of the F polymer particles having a melting temperature of 200 to 320° C. is 0.1 to 1 μm, and the D50 of the non-thermally fusible PTFE particles is 0.1 to 1 μm. is 200 to 320° C., the D50 of the particles of the F polymer is 1 to 4 μm, and the D50 of the non-heat-fusible PTFE particles is 0.1 to 1 μm.
The non-thermally fusible polymer means a polymer that does not have a temperature at which the melt flow rate is 1 g or more and 1000 g or less/10 minutes under the condition of a load of 49 N.

The F particles may contain resins or inorganic substances other than the F polymer, but preferably contain the F polymer as the main component. The content of the F polymer in the F particles is preferably 80% by mass or more, more preferably 100% by mass.

The spherical silica in the present composition is solid silica having a median diameter d (μm) of more than 0.6 μm and not more than 20 μm and a product d×A of the median diameter d and the specific surface area A (m ² /g) of It is in the range of 2.7 to 5.0 μm·m ² /g (2.7≦A×d50 (μm·m ² /g)≦5.0).
A dielectric loss tangent can be significantly reduced when the median diameter d exceeds 0.6 μm. On the other hand, as the median diameter d increases, the grain gauge value increases (measured by JIS K5400 grain gauge method). From the viewpoint of controlling the minimum thickness of the polymer layer when the present composition is molded into, for example, a polymer layer, the median diameter d is preferably more than 0.6 μm and 10 μm or less, more preferably 1 to 5 μm.
The median diameter d of the present spherical silica can be determined by a laser diffraction particle size distribution analyzer (for example, "MT3300EXII" manufactured by Microtrack Bell Co., Ltd.). Specifically, after the spherical silica powder is dispersed by irradiating ultrasonic waves three times for 60 seconds in the apparatus, measurement is performed twice for 60 seconds, and the average value is obtained.

The product d×A of the median diameter d and the specific surface area A of the present spherical silica is 2.7 to 5.0 μm·m ² /g, preferably 2.7 to 4.5 μm·m ² /g, More preferably, it is 2.7 to 4.0 μm·m ² /g. The theoretical value of dxA is 2.7 (derived from specific surface area = 6/(true density of silica 2.2 x median diameter d)), and values below this are practically unattainable. The larger the value of d×A, the larger the specific surface area per particle size and the larger the dielectric loss tangent. 0 μm·m ² /g or less.

The specific surface area A of the present spherical silica is preferably in the range of 0.2 to 2.0 m ² /g. When the specific surface area is 0.2 m ² /g or more, when the present spherical silica is contained in the present composition, there are sufficient contact points with the F polymer, so that compatibility with the F polymer is improved. When it is 0 m ² /g or less, the dielectric loss tangent can be reduced, so that the molded article obtained from the present composition can exhibit excellent low dielectric loss tangent, and the dispersibility in the molded article is improved. In addition, in the spherical silica of the present invention, the fact that there are few particles with a small median diameter and few surface roughnesses is considered to contribute to suppression of thickening of the present composition.
The specific surface area A is more preferably 1.5 m ² /g or less, still more preferably 1.0 m ² /g or less, and particularly preferably 0.8 m ² /g or less. In addition, it is substantially difficult to obtain one having a specific surface area A of less than 0.2 m ² /g.
In addition, the specific surface area of the present spherical silica is determined by nitrogen adsorption using a specific surface area/pore distribution measuring device (e.g., "BELSORP-miniII" manufactured by Microtrac Bell, "Tristar II" manufactured by Micromeritic, etc.). Calculated by the BET method based on the law.

The spherical silica preferably has a sphericity of 0.75 to 1.0. Since the specific surface area increases as the sphericity decreases, the dielectric loss tangent tends to increase, so the sphericity is preferably 0.75 or more. The sphericity is more preferably 0.90 or more, even more preferably 0.93 or more, and the closer to 1.0, the more preferable.
The sphericity is determined by measuring the maximum diameter (DL) and the short diameter (DS ) are measured, and the ratio (DS/DL) of the minimum diameter (DS) to the maximum diameter (DL) is calculated and can be represented by the average value.

The spherical silica preferably has a dielectric loss tangent of 0.0020 or less, more preferably 0.0010 or less, and even more preferably 0.0008 or less at a frequency of 1 GHz. When the dielectric loss tangent is 0.0020 or less, an excellent dielectric loss suppressing effect can be obtained, so that a substrate or sheet with improved high frequency characteristics can be obtained. The smaller the dielectric loss tangent, the more suppressed the transmission loss of the circuit, so the lower limit is not particularly limited.
The dielectric loss tangent can be measured by a perturbation resonator method using a dedicated device (for example, "Vector Network Analyzer E5063A" manufactured by Keycom Co., Ltd. (measurement conditions: test frequency 1 GHz, test temperature about 24 ° C., humidity about 45%, 3 measurements).

The spherical silica is preferably spherical silica having a viscosity of 5000 mPa·s or less in a kneaded product containing spherical silica measured by the following measuring method.
Measurement method: 6 parts by mass of boiled linseed oil specified in JIS K 5421:2000 and 8 parts by mass of spherical silica were mixed and kneaded at 2000 rpm for 3 minutes. ^-1 for 30 seconds and determine the viscosity at 30 seconds.

The IR peak intensity near 3746 cm ⁻¹ derived from isolated silanol groups on the surface of the present spherical silica is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less. An isolated silanol group is a silanol (Si—OH) group that is not bound to water or the like adsorbed to silica particles. The amount of isolated silanol (Si—OH) on the silica particle surface is obtained by IR measurement. Specifically, after normalizing the IR spectrum at 800 cm ⁻¹ and adjusting the baseline at 3800 cm ⁻¹ , the relative value of the Si—OH peak intensity near 3746 cm ⁻¹ is obtained. Dielectric loss can be reduced when the IR peak intensity near 3746 cm ⁻¹ derived from isolated silanol groups on the surface of the present spherical silica is 0.1 or less.

In addition, the maximum IR peak intensity at 3300 to 3700 cm ⁻¹ derived from the bonded silanol groups on the surface of the present spherical silica is preferably 0.2 or less, more preferably 0.17 or less, and 0.15 or less. More preferred. The bonded silanol group is a silanol (Si—OH) group bonded to water adsorbed to silica particles, silanol on the silica surface, or the like. The amount of bound silanol (Si—OH) on the silica particle surface is obtained by IR measurement. Specifically, after normalizing the IR spectrum at 800 cm ⁻¹ and matching the baseline at 3800 cm ⁻¹ , the relative value of the bonded Si—OH peak intensity is determined from the maximum peak among those at 3300 to 3700 cm ⁻¹ . . If the maximum IR peak intensity at 3300 to 3700 cm ⁻¹ derived from the bonded silanol groups on the surface of the spherical silica is 0.2 or less, the dielectric loss can be reduced.
Infrared spectroscopy (IR) spectrum can be measured by, for example, IR Prestige-21 (manufactured by Shimadzu Corporation) by a diffuse reflection method by dispersing spherical silica powder in diamond (measurement condition example: measurement range 400 ~4000 cm ^-1 , resolution 4 cm ^-1 , 128 times of integration).
Dilution to diamond powder is defined as [mass dilution rate] = ([sample mass]) / ([diamond mass] + [sample mass]), [mass dilution rate] = 85-2.5 x [BET ratio surface area].

The spherical silica is preferably nonporous particles from the viewpoint of electrical properties such as dielectric loss tangent and physical properties such as the viscosity of the composition. Specifically, the present spherical silica preferably has an oil absorption of 100 ml/100 g or less, more preferably 70 ml/100 g or less, and most preferably 50 ml/100 g or less.

The present spherical silica preferably contains titanium (Ti) in the range of 30 to 1500 ppm, more preferably 100 to 1000 ppm, even more preferably 100 to 500 ppm.

The present spherical silica may further contain other elements. Other elements include, for example, Na, K, Mg, Ca, Al, and Fe. Among other elements, the total content of alkali metals and alkaline earth metals is preferably 2000 ppm or less, more preferably 1000 ppm or less, and even more preferably 200 ppm or less.

The spherical silica may 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 made hydrophobic, water adsorption can be suppressed, and dielectric loss can be improved. , the dispersibility and the strength of a molded article such as a polymer layer obtained from the present composition are improved.
Silane coupling agents include aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, organosilazane compounds, and the like. Two or more of these may be used in combination.
It is preferable that the amount of the silane coupling agent attached is such that all the silanol groups present on the surface of the present spherical silica can react. Specifically, it is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, more preferably 2 parts by mass or less, and 1 part by mass or less with respect to 100 parts by mass of the present spherical silica. is more preferred.

The spherical silica is preferably spherical silica obtained by heat-treating a spherical silica precursor formed by a wet method.
The wet method refers to a method including a step of using a liquid silica source and gelling it to obtain a raw material for spherical silica powder.
The wet method includes, for example, a spraying method, an emulsion/gelation method, and the like.

The pore volume of the spherical silica precursor obtained by the wet method is desirably 0.3 to 2.2 ml/g.
Here, the pore volume is determined by a nitrogen adsorption method using a specific surface area/pore distribution measuring device (e.g., "BELSORP-miniII" manufactured by Microtrac Bell, "Tristar II" manufactured by Micromeritic, etc.). It is obtained by the BJH method based on
The ignition loss of the silica precursor obtained by the wet method is desirably 5.0 to 15.0% by mass.
Here, the ignition loss is obtained as the mass loss when 1 g of the silica precursor is dried by heating at 850° C. for 0.5 hours in accordance with JIS K0067.

In the heat treatment, the spherical silica powder is sintered to densify the shell, reduce the amount of silanol groups on the surface, and lower the dielectric loss tangent. The heat treatment temperature is preferably 700 to 1600°C.
The method of the heat treatment includes, for example, heat treatment by a stationary method, heat treatment by a rotary kiln method, heat treatment by spray combustion, and the like.

The present spherical silica obtained by such a method may be surface-treated with a silane coupling agent to allow the silanol groups present on the surface of the present spherical silica to react with the silane coupling agent.
Examples of the silane coupling agent include the above-described compounds, and two or more of them may be used in combination. The treatment amount of the silane coupling agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the spherical silica.
Examples of the method of surface treatment with a silane coupling agent include a dry method in which the silane coupling agent is sprayed onto the spherical silica, and a wet method in which the spherical silica is dispersed in a solvent and then the silane coupling agent is added for reaction. is mentioned.

The liquid dispersion medium contained in the present composition is a liquid having a function of dissolving, dispersing, or gelling the F particles or the present spherical silica, and the present composition is usually slurry or gel. The term "liquid" means that the viscosity is 10 mPa·s or less at 25°C.
The liquid dispersion medium is preferably degassed from the viewpoint of making the distribution of the present spherical silica uniform in the polymer layers constituting the layered product described below and suppressing voids.

The liquid dispersion medium may be water or a non-aqueous dispersion medium. Further, the liquid dispersion medium may be an aprotic dispersion medium or a protic dispersion medium.
Liquid dispersion media include compounds that are liquid at 25° C. under atmospheric pressure, such as water, alcohols, amides, ketones and esters.
Alcohols include methanol, ethanol, isopropanol, glycols (ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, etc.).
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, 1,3-dimethyl-2-imidazolidinone and the like.
Ketones include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, cycloheptanone.
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, γ- Valerolactone can be mentioned.

Two or more liquid dispersion media may be used in combination. When two or more types are used in combination, it is preferable that the liquid dispersion media of different types are compatible with each other.
The boiling point of the liquid dispersion medium is preferably in the range of 50 to 240°C.
The content of the liquid dispersion medium in 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, relative to the total mass of the composition. The content of the liquid dispersion medium is preferably 80% by mass or less, more preferably 70% by mass or less. Within this range, the present composition can be preferably handled as a liquid dispersion or a paste, and its dispersion stability and coatability are likely to be improved.

The content of the F particles in the composition is preferably 10% by mass or more, more preferably 20% by mass or more, relative to the total mass of the composition. From the viewpoint of dispersion stability of the composition, the content of the F particles is preferably 40% by mass or less, more preferably 30% by mass or less, relative to the total mass of the composition.
The content of the spherical silica in the present composition is preferably 10% by mass or more, more preferably 20% by mass or more, relative to the total mass of the composition. From the viewpoint of dispersion stability of the composition, the content of the spherical silica is preferably 60% by mass or less, more preferably 50% by mass or less, relative to the total mass of the composition.

Further, the content of the spherical silica is 10 to 60% by mass, preferably in the range of 20 to 50% by mass, and the content of the F particles is 10 to 40% by mass, based on the total mass of the composition. % by weight, preferably in the range of 10 to 30% by weight. Furthermore, the content of the present spherical silica in the present composition is preferably higher than the content of the F particles. Within this range, it is easy to obtain the present composition having excellent dispersion stability while suppressing an increase in viscosity, and it is easy to form a polymer layer having an arbitrary thickness, particularly a thick polymer layer, from the present composition.

The total content of the F particles and the spherical silica in the composition is preferably 20% by mass or more, more preferably 50% by mass or more, relative to the total mass of the composition. The total content of the F particles and the present spherical silica is preferably 95% by mass or less, more preferably 75% by mass or less, relative to the total mass of the composition.

The present composition may further contain an inorganic filler different from the present spherical silica, if necessary. The inorganic filler is a filler different from the present spherical silica, for example, boron nitride filler, aluminum nitride filler, beryllium oxide filler, silicate filler (silica filler, wollastonite filler, talc filler), metal oxide ( cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.) fillers and magnesium metasilicate (steatite) fillers. These fillers may be fired ceramic fillers.
At least part of the surface of the inorganic filler may be surface-treated with a silane coupling agent. Such a surface-treated inorganic filler has excellent affinity with the F particles and tends to improve the dispersibility of the present composition.

From the viewpoint of further improving dispersion stability and handling properties, the composition may further contain a surfactant. Preferably, the surfactant is nonionic.
The hydrophilic portion of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group.
The hydrophobic portion of the surfactant preferably has an acetylene group, polysiloxane group, perfluoroalkyl group or perfluoroalkenyl group. In other words, the surfactant is preferably an acetylene-based surfactant, a silicone-based surfactant or a fluorine-based surfactant, and more preferably a silicone-based surfactant.

Specific examples of such surfactants include “Futhergent (registered trademark)” series (manufactured by Neos Co., Ltd.), “Surflon (registered trademark)” series (manufactured by AGC Seimi Chemical Co., Ltd.), “Megafac (registered trademark) ” series (manufactured by DIC Corporation), “Unidyne (registered trademark)” series (manufactured by Daikin Industries, Ltd.), “BYK-347”, “BYK-349”, “BYK-378”, “BYK-3450”, “ BYK-3451", "BYK-3455", "BYK-3456" (manufactured by BYK-Chemie Japan Co., Ltd.), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), "Tergitol" series ( manufactured by Dow Chemical Company, "Tergitol TMN-100X", etc.).
When the present composition contains a surfactant, its amount is preferably in the range of 1 to 15% by weight in the present composition. In this case, the affinity between the components increases, and the dispersion stability and handleability of the present composition are likely to be improved.

The composition may further contain an aromatic polymer. Aromatic polymers may be thermoplastic or thermoset. Aromatic polymers may be included in the composition as precursors thereof. The aromatic polymer may be included in the composition as particles or dissolved in a liquid dispersion medium. If the composition contains water, the aromatic polymer is preferably water soluble.

Examples of aromatic polymers include aromatic polyimides, aromatic polyimide precursors (polyamic acids or salts thereof), aromatic polyamideimides, aromatic polyamideimide precursors, aromatic polyetherimides, aromatic polyetherimide precursors, aromatic group sulfide resins, aromatic sulfone resins, phenolic resins, aromatic epoxy resins, aromatic polyester resins (liquid crystalline aromatic polyesters, etc.), aromatic polyester amides (liquid crystalline aromatic polyester amides, etc.), aromatic maleimides, Polyphenylene ethers may be mentioned, with aromatic polyimide precursors, aromatic polyamideimides and aromatic polyamideimide precursors being preferred.
In this case, the aromatic polymer is likely to interact with the F polymer, and the molded article formed from the present composition tends to be excellent in adhesion to substrates such as metal foils and in UV absorption.
When the composition contains water, water-soluble aromatic polyamideimide precursors and water-soluble aromatic polyimide precursors are preferred.

Examples of aromatic polyimide precursors include polyamic acid obtained by polymerizing tetracarboxylic dianhydride and diamine in a solvent, and polyamic acid salt obtained by reacting the polyamic acid with aqueous ammonia or organic amine. Specific examples of aromatic polyimides or their precursors include "Neoplim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Company), "Spixeria (registered trademark)" series (manufactured by Somar), and "Q-PILON (registered trademark)." )" series (manufactured by PI Technical Research Institute), "WINGO" series (manufactured by Wingo Technology), "Tomide (registered trademark)" series (manufactured by T&K TOKA), "KPI-MX" series (manufactured by Kawamura Sangyo) , and “Upia (registered trademark)-AT” series (manufactured by Ube Industries, Ltd.).

The aromatic polyamideimide or its precursor includes a polyamideimide resin or a precursor thereof obtained by reacting a diisocyanate and/or a diamine with a tribasic acid anhydride (or tribasic acid chloride) as an acid component. be done.
Specific examples of the aromatic polyamideimide or its precursor include "HPC-1000" and "HPC-2100D" (manufactured by Showa Denko Materials).

When the composition further contains an aromatic polymer, the content thereof is preferably 0.01% by mass or more, more preferably 1% by mass or more, relative to the total mass of the composition. The content of the aromatic polymer is preferably 5% by mass or less, more preferably 3% by mass or less.
The content of the aromatic polymer in the composition is preferably less than 10% by mass, more preferably 5% by mass or less, relative to the content of the F polymer in the composition. The content of the aromatic polymer is preferably 0.1% by mass or more relative to the content of the F polymer.
When the present composition contains an aromatic polymer, the aromatic polymer functions as a dispersant or a binder for the present spherical silica and the F polymer, and tends to form a dense polymer layer. easy to disperse.
If the content of the aromatic polymer is within such a low range, the polymer layer tends to have excellent electrical properties.

In addition to an inorganic filler, a surfactant, and an aromatic polymer, the present composition contains a thixotropic agent, a viscosity modifier, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, Additives such as heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, mold release agents, surface treatment agents and flame retardants may be further contained.

The viscosity of the present composition is preferably 10 mPa·s or more, more preferably 50 mPa·s or more. The viscosity of the present composition is preferably 10000 mPa·s or less, more preferably 1000 mPa·s or less, and even more preferably 500 mPa·s or less.
The viscosity of the composition is preferably in the range of 50-1000 mPa·s. In this case, since the present composition has excellent coatability, it is easy to form a molded product such as a polymer layer having an arbitrary thickness from the present composition.
The thixotropic ratio of the present composition is preferably 1 or more. The thixotropic ratio of the present composition is preferably 3 or less, more preferably 2 or less. In this case, the present composition is not only excellent in coatability but also excellent in homogeneity, so that it is easy to form a molded product such as a denser polymer layer.

The present composition can be produced by mixing the F particles, the present spherical silica, and a liquid dispersion medium.
The mixing method is not particularly limited as long as the F particles, the present spherical silica, the liquid dispersion medium and, if necessary, other components are uniformly mixed. (b) a method of pre-mixing the F particles and the liquid dispersion medium and the present spherical silica and the liquid dispersion medium, respectively, and then further mixing the resulting two mixtures; (c) the F particles and the present spherical silica; are mixed in advance to form a powder mixture, and the resulting powder mixture and a liquid dispersion medium are mixed. The above method (b) or (c) is preferable from the viewpoint that the resulting composition tends to be homogeneous.
When the present composition further contains an inorganic filler, a surfactant, an aromatic polymer, other components that may be optionally added, etc., the liquid dispersion medium, the F particles, and the present spherical silica are mixed. It is preferable to add it to the liquid dispersion medium in advance. When the composition contains an aromatic polymer, it may be mixed with the F particles as a varnish of the aromatic polymer. Solvents constituting the varnish include N-methyl-2-pyrrolidone, cyclohexanone and toluene.

Mixing devices used to obtain the present composition include stirring devices equipped with blades (Henschel mixer, pressure kneader, Banbury mixer, planetary mixer, etc.), grinding devices equipped with media (ball mills, attritors, baskets, etc.). mill, sand mill, sand grinder, dyno mill, dispermat, SC mill, spike mill or agitator mill, etc.), dispersing equipment with other mechanisms (microfluidizer, nanomizer, ultimizer, ultrasonic homogenizer, desolver, disper, high-speed impeller, rotation/revolution stirrer, colloid mill, thin-film swirling high-speed mixer, etc.).

Further, as a suitable method for producing the present composition, the F particles, the present spherical silica, and part of the liquid dispersion medium are kneaded in advance to obtain a kneaded product, and the remaining liquid dispersion medium is added to the kneaded product. are added and mixed to obtain the present composition. The liquid dispersion medium used for kneading and addition may be the same type of liquid dispersion medium or different types of liquid dispersion mediums. When the present composition further contains other components such as inorganic fillers, surfactants, and aromatic polymers, the other components may be mixed during kneading, and when the remaining liquid dispersion medium is added to the kneaded product, may be mixed into
Examples of the method for mixing each component when pre-kneading the F particles, the present spherical silica, and part of the liquid dispersion medium include the methods (a), (b), and (c) described above. The above method (b) or (c) is preferable from the viewpoint that the resulting composition tends to be homogeneous.
Mixing in kneading is preferably carried out using a planetary mixer. A planetary mixer is a stirring device having two stirring blades that rotate and revolve with each other. Mixing in the addition is preferably carried out using a thin-film rotating high-speed mixer. A thin-film swirling high-speed mixer is a stirring device that spreads F particles and a liquid dispersion medium in a thin film form on the inner wall surface of a cylindrical stirring tank, swirls them, and mixes them while exerting centrifugal force.

The kneaded product obtained by kneading may be a paste (a paste having a viscosity of 1000 to 100000 mPa s, etc.), or a wet powder (a wet powder having a viscosity of 10000 to 100000 Pa s as measured by a capillograph). (dough), etc.).
The viscosity measured by a capillary graph is defined by using a capillary with a capillary length of 10 mm and a capillary radius of 1 mm, a furnace body diameter of 9.55 mm, a load cell capacity of 2 t, a temperature of 25 ° C., and a shear rate of 1 s ⁻ It is a value measured as ¹ .

The composition is useful as a coating material for imparting insulation, heat resistance, corrosion resistance, chemical resistance, water resistance, impact resistance, and thermal conductivity.
Specifically, the present composition can be used for printed wiring boards, thermal interface materials, substrates for power modules, coils used in power devices such as motors, automotive engines, heat exchangers, vials, syringes, Ampoules, medical wires, secondary batteries such as lithium ion batteries, primary batteries such as lithium batteries, radical batteries, solar cells, fuel cells, lithium ion capacitors, hybrid capacitors, capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.) ), electrochromic elements, electrochemical switching elements, electrode binders, electrode separators, and electrodes (positive and negative electrodes).
The composition is also useful as an adhesive for bonding parts together. Specifically, the composition can be used for adhesion of ceramic parts, adhesion of metal parts, adhesion of electronic parts such as IC chips, resistors and capacitors on substrates of semiconductor elements and module parts, adhesion of circuit boards and heat sinks, LED It can be used for bonding chips to substrates.

In particular, the present composition is useful as a material for forming a polymer layer in a printed wiring board, specifically a copper foil with a polymer layer having a polymer layer formed from the present composition on the surface of the copper foil. . As shown in Table 1 below, spherical silica itself is inherently excellent in electrical properties (especially dielectric loss tangent) and low linear expansion, but in the polymer layer of the polymer layer-coated copper foil, it is difficult to express such physical properties at a high level. was difficult. By using the present composition, a polymer layer-coated copper foil having a polymer layer having such spherical silica physical properties and F polymer physical properties can be easily obtained due to the mechanism of action described above.

The present composition is applied to at least one surface of a substrate and heated to form a polymer layer containing the F polymer and the present spherical silica (hereinafter also referred to as "F layer"). It is preferably used.
For example, the present composition is applied to the surface of a substrate to form a liquid coating (wet film) composed of the present composition, and then the liquid dispersion medium is removed from the liquid coating by heating to form F on the surface of the substrate. A polymer layer can be formed that includes the polymer and the spherical silica.
Furthermore, it is preferable to bake the F polymer of the obtained polymer layer. By heating and sintering the F polymer, it is possible to produce a laminate having a substrate layer and a polymer layer containing the sintered F polymer and the present spherical silica on the surface of the substrate layer. The heating for removing the liquid medium and the heating for baking the F polymer can be performed continuously.

Substrates include metal substrates such as metal foils of copper, nickel, aluminum, titanium and alloys thereof, tetrafluoroethylene-based polymers, polyimides, polyarylates, polysulfones, polyallylsulfones, polyamides, polyetheramides, and polyphenylene sulfides. , polyallyl ether ketone, polyamideimide, liquid crystalline polyester, and liquid crystalline polyester amide. and glass substrates.
Examples of the shape of the substrate include planar, curved, and uneven shapes. Moreover, the shape of the substrate may be any of foil, plate, film, and fiber.

The ten-point average roughness of the substrate surface is preferably less than 0.1 μm, more preferably 0.05 μm or less. The ten-point average roughness is preferably 0.001 μm or more. Even with such a non-roughened base material, according to this method, a polymer layer with excellent uniformity can be obtained, so a laminate with excellent peel strength can be obtained. The ten-point average roughness of the surface of the base material is a value specified in Annex JA of JIS B 0601:2013.
The thickness of the substrate is preferably 2-100 μm. When the substrate is a metal foil, the thickness of the substrate is preferably 1-35 μm. The substrate may also be a carrier-attached copper foil, which is an ultra-thin copper foil (thickness of 2 to 5 μm) laminated on a carrier copper foil via a release layer. When the substrate is a polyimide film, the thickness of the substrate is preferably 10-50 μm.

The outermost surface of the substrate may be further surface-treated in order to further improve the low linear expansion property and adhesiveness of the laminate.
Examples of surface treatment methods include annealing treatment, corona treatment, plasma treatment, ozone treatment, excimer treatment, and silane coupling treatment.
The annealing conditions are preferably a temperature of 120 to 180° C., a pressure of 0.005 to 0.015 MPa, and a time of 30 to 120 minutes.
Gases used for plasma treatment include oxygen gas, nitrogen gas, rare gas (such as argon), hydrogen gas, ammonia gas, and vinyl acetate. These gases may be used in combination of two or more.

The method of applying the present composition to the surface of the substrate may be any method as long as a stable liquid film (wet film) composed of the present composition is formed on the surface of the substrate. , immersion method, and coating method is preferred. By using the coating method, a liquid coating can be efficiently formed on the surface of the metal substrate with simple equipment.
Coating methods include spray method, roll coating method, spin coating method, gravure coating method, micro gravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, fountain-meyer bar method, and slot die coating. law.

The F layer is preferably formed by removing the liquid dispersion medium from the liquid film (wet film) by heating, and then heating to a higher temperature to bake the polymer. The temperature for removing the liquid dispersion medium is preferably as low as possible, preferably 50 to 150° C. lower than the boiling point of the liquid dispersion medium. For example, when N-methyl-2-pyrrolidone having a boiling point of about 200°C is used, it is preferable to heat at 150°C or lower, preferably 100 to 120°C. In the step of removing the liquid dispersion medium, air may be blown to promote the removal of the liquid dispersion medium by air drying. In this heating, the liquid dispersion medium does not necessarily have to be completely removed, and may be removed to such an extent that the layer formed by packing the F particles can maintain a self-supporting film.

After removing the liquid dispersion medium, the polymer layer on the substrate is preferably heated to a temperature range where the F polymer is baked to form an F layer containing the baked product of the F polymer. It is preferred to calcine the polymer. The F layer preferably contains a sintered F polymer.
A heating apparatus for each heating includes an oven and a ventilation drying oven. The heat source in the apparatus may be a contact heat source (hot air, hot plate, etc.) or a non-contact heat source (infrared radiation, etc.).
Each heating may be performed under normal pressure or under reduced pressure.
The atmosphere in each heating may be either an air atmosphere or an inert gas (helium gas, neon gas, argon gas, nitrogen gas, etc.) atmosphere.
The F layer is formed through the steps of applying the present composition to the substrate surface and heating. For the purpose of obtaining a thick F layer, the application and heating of the present composition may be repeated multiple times to form the F layer. For example, the composition may be applied to the surface of a substrate and heated to form an F layer, and the composition may be applied to the surface of the F layer and heated to form a second F layer. . In addition, at the stage where the present composition is applied to the surface of the substrate and heated to remove the liquid dispersion medium, the present composition may be further applied to the surface and heated to form the F layer.

The thickness of the F layer is preferably 50 µm or more, more preferably 100 µm or more. The thickness of the F layer is preferably 1000 μm or less. Even when the F layer is thick, it is possible to obtain a polymer layer in which the present spherical silica has excellent dispersibility due to the mechanism of action described above.

The peel strength between the F layer and the substrate layer is preferably 10 N/cm or more, more preferably 15 N/cm or more. The peel strength is preferably 100 N/cm or less.
Moreover, the tensile strength of the F layer is preferably 5 MPa or more, more preferably 10 MPa or more. The tensile strength is preferably 100 MPa or less.
By using this composition, it is possible to easily form a laminate having excellent peel strength between the F layer and the substrate layer and excellent tensile strength of the F layer without impairing the physical properties of the F polymer in the F layer.

The composition may be applied to only one surface of the substrate or may be applied to both surfaces of the substrate. In the former case, a laminate having a substrate layer and an F layer on one surface of the substrate layer is obtained, and in the latter case, the substrate layer and the F layer are provided on both surfaces of the substrate layer. A laminate is obtained.
Preferred specific examples of the laminate include a metal foil and a metal-clad laminate having an F layer on at least one surface of the metal foil, a polyimide film, and a multilayer film having an F layer on both surfaces of the polyimide film. is mentioned. These laminates are excellent in various physical properties such as electrical properties, and thus are suitable as printed circuit board materials and the like, and can be used for manufacturing flexible printed circuit boards and rigid printed circuit boards.

Another substrate may be further laminated on the outermost surface of the laminate.
Other substrates include a metal substrate, a heat-resistant resin film, a prepreg that is a precursor of a fiber-reinforced resin plate, a laminate having a heat-resistant resin film layer, and a laminate having a prepreg layer. Examples of the metal substrate include the metal substrates described above. A heat-resistant resin film is a film containing one or more heat-resistant resins, and examples of heat-resistant resins include the resins described above.
Furthermore, the substrate may be removed from the laminate. In this case, a film consisting of a single F layer is obtained.

Laminates, laminates of laminates with other substrates, and films composed of F layers are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sporting goods, food industry supplies, paints, cosmetics, and the like. be.
Specifically, electric wire coating materials (wires for aircraft, etc.), enameled wire coating materials used for motors of electric vehicles, etc., electrical insulating tapes, insulating tapes for oil drilling, materials for printed circuit boards, separation membranes (precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, fuel cells, etc.), copy rolls, furniture, automobile dashboards, home appliances Product covers, sliding parts (load bearings, slide shafts, valves, bearings, bushes, seals, thrust washers, wear rings, pistons, slide switches, gears, cams, belt conveyors, food conveyor belts, etc.), wear pads , wear strips, tube lamps, test sockets, wafer guides, wear parts for centrifugal pumps, hydrocarbon, chemical and water supply pumps, tools (shovels, files, awls, saws, etc.), boilers, hoppers, pipes, ovens, baking molds , chutes, dies, toilet bowls, container covering materials, power devices, transistors, thyristors, rectifiers, transformers, power MOSFETs, CPUs, heat dissipation fins, metal heat dissipation plates, blades for wind turbines, wind power generation facilities, aircraft, etc., heat dissipation for automobiles It can also be suitably used as a substrate and a heat dissipation member for wireless communication devices (for example, the wireless communication devices described in WO2020/008691 and WO2020/031419).

The composition, the method for producing the composition, the method for producing a laminate having a polymer layer formed from the composition, and the laminate have been described above. Not limited.
For example, the present composition and the laminate may be added with any other configuration in the configurations of the above-described embodiments, or may be replaced with any configuration that exhibits similar functions. In addition, the method for producing the present composition and the method for producing the laminate may additionally have any other step in the configuration of the above embodiment, or may be replaced with any step that produces the same effect. It's okay.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
1. Preparation of each component [F particles]
F particle 1: containing 97.9 mol%, 0.1 mol% and 2.0 mol% of TFE units, NAH units and PPVE units in this order, a fluorine content of 76% by mass, and a carbonyl group-containing group in the main chain Particles composed of F polymer 1 having 1000 carbon atoms per 1×10 ⁶ carbon atoms (D50: 2.1 μm)
F particle 2: containing 97.5 mol% and 2.5 mol% of TFE units and PPVE units in this order, a fluorine content of 76% by mass, and 25 carbonyl group-containing groups per 1×10 ⁶ main chain carbon atoms Particles made of F polymer 2 (D50: 2.5 μm)
[Spherical silica]
Spherical silica 1: Spherical silica powder ("H-31" manufactured by AGC Si Tech Co., Ltd., median diameter d = 3.5 µm, Ti content 300 ppm) produced by a wet method was heat-treated at 1300 ° C. for 1 hour ( Median diameter d=3 μm, specific surface area 1.3 m ² /g)
Spherical silica 2: Spherical silica produced from raw material silica produced by the VMC method ("SC-04" manufactured by Admatechs, median diameter d = 1.5 µm, specific surface area 4.5 m ² /g, Ti content 28 ppm )
Spherical silica 3: Spherical silica having a median diameter d of 0.6 μm and a specific surface area of 6.2 m ² /g [liquid dispersion medium]
NMP: N-methylpyrrolidone [surfactant]
Surfactant 1: nonionic surfactant (Ftergent 710FL)

2. Production example of liquid composition [Example 1]
25 parts by mass of F particles 1, 50 parts by mass of spherical silica 1, 5 parts by mass of surfactant 1, and 20 parts by mass of NMP are kneaded in a rotation or revolution mixer (Awatori Mixer, manufactured by Thinky) to form a paste. 55 parts by mass of NMP was further added to this kneaded product and stirred at 2000 rpm for 5 minutes to obtain a liquid composition 1. The resulting liquid composition 1 had a viscosity of less than 100 mPa·s.
[Example 2]
Liquid composition 2 was obtained in the same manner as in Example 1, except that 50 parts by mass of spherical silica 2 was used instead of 50 parts by mass of spherical silica 1. The obtained liquid composition 2 had a viscosity of more than 100 mPa·s.
[Example 3]
Liquid composition 3 was obtained in the same manner as in Example 1, except that 50 parts by mass of spherical silica 3 was used instead of 50 parts by mass of spherical silica 1. The resulting liquid composition 3 had a viscosity of more than 100 mPa·s.
[Example 4]
A liquid composition 4 was obtained in the same manner as in Example 1 except that 25 parts by mass of F particles 2 were used instead of 25 parts by mass of F particles 1 . The resulting liquid composition 4 had a viscosity of less than 100 mPa·s.

3. Production Example of Laminate [Example 4]
Liquid composition 1 was applied to the surface of a copper foil (thickness: 18 μm) to form a wet film. Next, the metal foil on which the wet film was formed was passed through a drying furnace at 120° C. for 5 minutes and dried by heating to obtain a dry film. The dry film was then heated at 380° C. for 3 minutes in a nitrogen oven. As a result, a laminate 1, which is a polymer layer-attached copper foil, was produced, which has a copper foil and a polymer layer (thickness: 50 μm) as a molding containing F polymer and spherical silica 1 on its surface.
[Examples 5-7]
In the same manner as in Example 4, except for changing the liquid composition to be used, a laminate 2 (Example 5) was produced from the liquid composition 2, a laminate 3 (Example 6) was produced from the liquid composition 3, and a laminate 3 (Example 6) was produced from the liquid composition 4. Laminate 4 (Example 7) was obtained respectively.

4. Evaluation 4-1. Dispersion Stability of Liquid Composition Each liquid composition was allowed to stand at 25° C. for 30 days, then the state of dispersion was visually observed, and the long-term dispersion stability was evaluated according to the following criteria. Table 2 shows the results.
<Evaluation Criteria>
〇: No viscosity increase and component sedimentation not confirmed △: Layer separation is confirmed, but it can be easily redispersed, and no thickening after redispersion is confirmed ×: Thickness increase or component sedimentation is confirmed

4-2. Evaluation Example of Laminate As a result of visually confirming the surface of the polymer layer in each laminate, the smoothness of laminate 1, laminate 4, laminate 3, and laminate 2 was higher in this order.
In addition, for each laminate, the copper foil was removed by etching with an aqueous ferric chloride solution to obtain a single polymer layer, cut into a 180 mm square square test piece, and JIS C 6471: It is specified in 1995. As a result of measuring the coefficient of linear expansion according to the method for measuring the coefficient of linear expansion, the coefficient of linear expansion is in the order of the polymer layer of the laminate 1, the polymer layer of the laminate 4, the polymer layer of the laminate 3, and the polymer layer of the laminate 2. was low.
Further, the dielectric loss tangent of each polymer layer was measured by SPDR (split post dielectric resonance method, measurement frequency: 10 GHz), and the dielectric loss tangent of the polymer layer of laminate 1 was the lowest.

4. Film production example [Example 8]
A copper foil with a polymer layer was produced from each liquid composition in the same manner as in Example 4, except that the thickness of the polymer layer as the molded product was 150 μm, and the copper foil was removed by etching. of films were produced. The film formed from liquid composition 1 had the highest surface smoothness of the resulting film.

According to the present invention, a liquid composition having excellent uniformity and dispersion stability and low viscosity can be obtained. A laminate obtained from the liquid composition is excellent in electrical properties such as a low dielectric loss tangent, and can be suitably used as a material for printed wiring boards, for example.
In addition, the entire contents of the specification, claims and abstract of Japanese Patent Application No. 2021-193907 filed on November 30, 2021 are cited here and incorporated as disclosure of the specification of the present invention. is.

Claims

Particles of a tetrafluoroethylene-based polymer, a median diameter d (μm) of more than 0.6 μm and 20 μm or less, and a product d×A of the median diameter d and the specific surface area A (m 2 /g) of 2.7 to 5.0 μm. - A liquid composition comprising m 2 /g of spherical silica and a liquid dispersion medium.
The liquid composition according to claim 1, wherein the tetrafluoroethylene-based polymer is a hot-melt tetrafluoroethylene-based polymer.
The liquid composition according to claim 1 or 2, wherein the tetrafluoroethylene-based polymer contains units based on perfluoro(alkyl vinyl ether) and has an oxygen-containing polar group.
The liquid composition according to any one of claims 1 to 3, wherein the spherical silica has a specific surface area of 0.2 to 2.0 m 2 /g.
5. The liquid composition according to any one of claims 1 to 4, wherein the maximum IR peak intensity at 3300 to 3700 cm -1 derived from bound silanol groups on the surface of said spherical silica is 0.2 or less.
The content of the spherical silica is 10 to 60% by mass, the content of the particles of the tetrafluoroethylene polymer is 10 to 40% by mass, and the liquid dispersion is based on the total mass of the liquid composition. The liquid composition according to any one of claims 1 to 5, wherein the content of the medium is 5% by mass or more.
The liquid composition according to any one of claims 1 to 6, wherein the content of said spherical silica is greater than the content of said tetrafluoroethylene-based polymer particles.
The liquid composition according to any one of claims 1 to 7, further comprising a surfactant.
The liquid composition according to any one of claims 1 to 8, further comprising an aromatic polymer.
The liquid composition according to any one of claims 1 to 9, further comprising an inorganic filler different from the spherical silica.
The liquid composition according to any one of claims 1 to 10, which has a viscosity of 50 to 1000 mPa·s.
The method for producing a liquid composition according to any one of claims 1 to 11, wherein the tetrafluoroethylene-based polymer particles, the spherical silica, and the liquid dispersion medium are mixed to obtain the liquid composition.
A method for producing the liquid composition according to any one of claims 1 to 11,
A composition containing the particles of the tetrafluoroethylene-based polymer, the spherical silica, and a part of the liquid dispersion medium is kneaded to obtain a kneaded material, and the remaining liquid dispersion medium is added to the kneaded material. and mixing to obtain the liquid composition.
The liquid composition according to any one of claims 1 to 11 is applied to the surface of a substrate to form a liquid coating composed of the liquid composition, and then the liquid dispersion medium is removed from the liquid coating by heating. and forming a polymer layer containing the tetrafluoroethylene-based polymer and the spherical silica on the surface of the substrate.
a substrate, and a polymer layer provided on the surface of the substrate and containing a tetrafluoroethylene-based polymer formed from the liquid composition according to any one of claims 1 to 11 and the spherical silica; laminate.