JP7468520B2 - Liquid Composition - Google Patents

Description

The present invention relates to a liquid composition comprising a powder of a tetrafluoroethylene-based polymer and a specified aromatic polymer.

Tetrafluoroethylene polymers such as polytetrafluoroethylene (PTFE) are excellent in physical properties such as chemical resistance, water and oil repellency, heat resistance, and electrical properties, and are used in a variety of industrial applications by utilizing these physical properties.
When a liquid composition containing a powder of a tetrafluoroethylene-based polymer is applied to the surface of various substrates, a molded article having physical properties based on the tetrafluoroethylene-based polymer can be formed on the surface.
For this reason, such liquid compositions are useful as materials for polymer-layered metal foils having an insulating polymer layer on the surface of the metal foil, which are used in printed wiring boards that transmit high-frequency signals (see Patent Documents 1 and 2).

Attempts have also been made to improve the physical properties of molded articles formed from such liquid compositions by further blending functional materials with them, but tetrafluoroethylene-based polymers have low surface tension and are unlikely to interact with other components.
Therefore, when various functional materials are blended into such a liquid composition, the dispersibility of the material is further reduced, making the composition unsuitable for use.
Patent Documents 3 and 4 propose that when a polyimide precursor varnish is blended as a main component in such a liquid composition, a highly hydrophobic fluorine-based additive is blended in advance in the liquid composition to control the water content, thereby improving the dispersibility of the liquid composition after blending with the varnish.

International Publication No. 2016/159102 JP 2017-078102 A JP 2017-066327 A JP 2016-210886 A

When manufacturing printed circuit boards containing tetrafluoroethylene polymers, the use of metal foils with low surface roughness (low-roughening metal foils) is being considered, particularly to reduce transmission loss. In such cases, the insulating polymer layer is required to have not only good electrical properties, but also strong adhesion to the metal foil in order to reduce defects (peeling, swelling, warping, etc.) during subsequent processing.

Although tetrafluoroethylene-based polymers have excellent electrical properties (low dielectric constant, low dielectric tangent, etc.) and heat resistance (heat resistance that can withstand the solder reflow process when processing the polymer-layered metal foil), they have poor adhesion to metals due to their low surface tension. In particular, when a low-roughening metal foil is used as the polymer layer of a polymer-layered metal foil, the physical adhesive effect (anchor effect) between the polymer layer and the copper foil decreases, making it even more difficult to firmly adhere the two together. Furthermore, the linear expansion coefficient of tetrafluoroethylene-based polymers is generally higher than that of metals, and the polymer-layered metal foil is prone to defects (peeling, swelling, warping) when heated during processing.

The inventors have discovered that in a polymer-layered metal foil having a low-roughening metal foil and a layer containing a tetrafluoroethylene-based polymer in that order, it becomes even more difficult to firmly adhere the two together without impairing their electrical properties and to suppress problems caused by heating.
An object of the present invention is to solve the above problems and to provide a liquid composition containing a tetrafluoroethylene-based polymer powder, which enables a polymer-layered metal foil to be easily produced.

Furthermore, according to the studies of the present inventors, the dispersibility of the liquid composition after blending with the varnish in the embodiments of Patent Documents 3 and 4 is still insufficient. In particular, when the amount of the tetrafluoroethylene-based polymer is large, the dispersibility is likely to decrease significantly. The dispersion state of the tetrafluoroethylene-based polymer in the molded article formed therefrom and the physical properties thereof are also still insufficient.
Furthermore, when a thin molded product (such as a thin film) is formed from the liquid composition of the embodiment of Patent Document 4, defects are likely to be formed and a dense thin film cannot be obtained.
The present inventors have found that by using a specific polyimide in which imidization has progressed rather than a polyamic acid (polyimide precursor) in which imidization has not progressed, the dispersibility in the liquid composition is improved and the physical properties of the layer formed therefrom are improved, in particular the physical properties of the tetrafluoroethylene-based polymer are highly expressed.

The inventors have also discovered that the use of a surfactant having hydrophilicity within a specified range improves the dispersibility of the liquid composition and improves the physical properties of the layer formed therefrom, in particular the physical properties of the tetrafluoroethylene-based polymer are highly expressed.
Furthermore, the present inventors have found that if a predetermined amount of water is deliberately added to the liquid composition, a dense polymer layer can be formed, and that in this case, a dense polymer layer can be formed even if the content of the tetrafluoroethylene-based polymer in the liquid composition is increased in order to strongly express the physical properties of the tetrafluoroethylene-based polymer.
The present invention is based on such findings, and has an object to provide a liquid composition which has excellent dispersibility and is capable of forming a dense polymer layer.

The present invention has the following aspects.
[1] A liquid composition comprising a powder of a tetrafluoroethylene-based polymer, a liquid dispersion medium, and an aromatic polymer having an amide structure, an imide structure or an ester structure in its main chain and being soluble in the liquid dispersion medium.
[2] A liquid composition comprising a tetrafluoroethylene-based polymer powder, a binder resin, and a liquid dispersion medium, wherein the binder resin is soluble in the liquid dispersion medium and is an aromatic polyamideimide or aromatic polyimide having a 20% weight loss temperature of 260°C or higher.
[3] The liquid composition according to [2], wherein a mass ratio of the content of the binder resin to the content of the tetrafluoroethylene-based polymer is 0.05 or less.
[4] The liquid composition according to [2] or [3], wherein the tetrafluoroethylene-based polymer is a heat-fusible tetrafluoroethylene-based polymer, and the glass transition point of the binder resin is equal to or lower than the melting temperature of the tetrafluoroethylene-based polymer.
[5] A liquid composition comprising a tetrafluoroethylene-based polymer powder, an aromatic polyimide having an imidization rate of 1% or more, and an aprotic polar liquid dispersion medium.
[6] The liquid composition according to [5], wherein the content of the tetrafluoroethylene-based polymer is 10 to 50 mass % and the content of the aromatic polyimide is 0.01 to 50 mass %.
[7] The liquid composition according to [5] or [6], wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) and having a melting temperature of 260 to 320° C.
[8] The liquid composition according to any one of [5] to [7], wherein the aromatic polyimide contains a unit based on an acid dianhydride of an aromatic tetracarboxylic acid and an aromatic diamine or an aliphatic diamine having a structure in which two or more arylene groups are linked via a linking group.
[9] A liquid composition comprising a powder of a tetrafluoroethylene-based polymer, at least one aromatic polymer or a precursor thereof selected from the group consisting of aromatic polyamideimide, aromatic polyimide, and aromatic polyester, a surfactant having a hydroxyl group and an oxyalkylene group, and an aprotic polar liquid dispersion medium, wherein the content of the tetrafluoroethylene-based polymer is equal to or greater than the content of the aromatic polymer or the precursor thereof, the hydroxyl value of the surfactant is 100 mgKOH/g or less, and the content of the oxyalkylene group is 10 mass% or more.
[10] The liquid composition according to [9], wherein the content of the tetrafluoroethylene-based polymer is 10 to 50 mass % and the content of the aromatic polymer or a precursor thereof is 0.01 to 50 mass %.
[11] The liquid composition according to [9] or [10], wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) and having a melting temperature of 260 to 320° C.
[12] The liquid composition according to any one of [9] to [11], wherein the surfactant further has a perfluoroalkyl group or a perfluoroalkenyl group.
[13] A liquid composition comprising a tetrafluoroethylene-based polymer powder, an aromatic polyimide or a precursor thereof, and a non-aqueous liquid dispersion medium, the content of the tetrafluoroethylene-based polymer being 10 mass% or more and the water content being 1,000 to 50,000 ppm.
[14] The liquid composition according to [13], wherein the content of the aromatic polyimide or a precursor thereof is 10 mass % or more.
[15] The liquid composition according to [13] or [14], wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer containing units based on perfluoro(alkyl vinyl ether).

According to the present invention, a liquid composition is obtained that has excellent dispersibility and is capable of forming dense molded articles that have adhesion and high-grade tetrafluoroethylene-based polymer properties.

The following terms have the following meanings.
The "average particle size of a powder (D50)" is the cumulative 50% volumetric diameter of a powder determined by a laser diffraction/scattering method. In other words, the particle size distribution of a powder is measured by a laser diffraction/scattering method, and a cumulative curve is calculated with the total volume of the particle group set as 100%, and the average particle size of the powder (D50) is the particle size at the point on the cumulative curve where the cumulative volume is 50%.
"D90 of powder" is the volume-based cumulative 90% diameter of the powder, determined in the same manner.
The particle size of the powder can be measured by dispersing the powder in water and using a laser diffraction/scattering type particle size distribution measuring device (LA-920 measuring device, manufactured by Horiba, Ltd.).
The "melt viscosity of polymer" is a value measured in accordance with ASTM D 1238 using a flow tester and a 2Φ-8L die, with a polymer sample (2 g) that had been preheated at the measurement temperature for 5 minutes being held at the measurement temperature under a load of 0.7 MPa.
The "melting temperature (melting point) of a polymer" is the temperature corresponding to the maximum value of the melting peak of the polymer as measured by differential scanning calorimetry (DSC).
The "glass transition point of a polymer" is a value measured by analyzing a polymer using a dynamic mechanical analysis (DMA) method.
The "viscosity" is the viscosity of the liquid measured using a Brookfield viscometer at room temperature (25° C.) and a rotation speed of 30 rpm. The measurement is repeated three times, and the average value of the three measured values is used.
The "thixotropy ratio" is a value (η1/η2) calculated by dividing the viscosity η1 of the liquid measured at a rotation speed of 30 rpm by the viscosity η2 of the liquid measured at a rotation speed of 60 rpm.
"Ten-point average roughness (Rzjis)" is a value specified in Annex JA of JIS B 0601:2013.
The "unit" in a polymer may be an atomic group formed directly from a monomer by a polymerization reaction, or may be an atomic group in which a part of the structure is converted by treating a polymer obtained by a polymerization reaction with a predetermined method. A unit based on monomer A contained in a polymer is also simply referred to as a "monomer A unit".
"(Meth)acrylate" is a general term for acrylate and methacrylate.
The "weight average molecular weight (Mw)" is a value of the polymer measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

The liquid composition of the present invention (present composition) comprises a powder (hereinafter also referred to as "F powder") of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer"), a liquid dispersion medium, and an aromatic polymer (hereinafter also referred to as "aromatic polymer") having an amide structure, imide structure or ester structure in its main chain and soluble in the liquid dispersion medium.
This composition can be said to be a dispersion in which the F powder is highly dispersed in an aromatic polymer varnish. The aromatic polymer is a compound different from the F polymer, and is preferably a compound having a solubility in a liquid dispersion medium at 25° C. (g/100 g of liquid dispersion medium) of 5 or more. The solubility of the aromatic polymer is preferably 30 or less.

A first aspect of the present composition (hereinafter also referred to as the present composition (1)) includes an F powder, a binder resin, and a liquid dispersion medium, in which the binder resin is soluble in the liquid dispersion medium and is an aromatic polyamideimide or aromatic polyimide having a 20% weight loss temperature of 260° C. or higher.
The reason why a layer (coating film) (including embodiments such as molded articles) (hereinafter also simply referred to as a "layer (coating film)") formed from the present composition (1) has excellent adhesion to a substrate and surface smoothness is not necessarily clear, but is thought to be as follows.

In the present composition (1), the formation of a layer (coating film) proceeds by packing of the F powder and baking of the F polymer (usually by heating at a temperature of 260° C. or higher). During packing, the binder resin binds to the F powder, exerting the effect of suppressing the powder from falling off. In the present invention, which uses an F polymer with low molecular interactions, such an effect is considered to be significant.
On the other hand, during baking, the binder resin can deteriorate the properties and physical properties of the layer (coating film). Specifically, the present inventors have found that residues (decomposition gases) resulting from the decomposition of the binder resin and by-products (water, carbon dioxide, etc.) resulting from the reaction of the binder resin itself tend to roughen the interface of the layer (coating film) to be formed. In particular, the present inventors have found that when the substrate on which the layer (coating film) is formed has high smoothness, such roughness significantly reduces the adhesion between the layer (coating film) and the substrate.
As a result of intensive research, the present inventors discovered that by using a specific binder resin, it is possible to easily form a layer (coating film) while suppressing such a decrease in adhesion and without impairing the original physical properties of the F polymer, and thus completed the present invention.

The F polymer in the composition (1) is a polymer that contains units (TFE units) based on tetrafluoroethylene (TFE).The F polymer may be a homopolymer of TFE, or may be a copolymer of TFE and TFE and other comonomers.F polymer may be used alone or may be used in combination of two or more kinds.
The F polymer preferably contains 90 to 100 mol % of TFE units based on the total units constituting the polymer, and the fluorine content of the F polymer is preferably 70 to 76 mass %, more preferably 72 to 76 mass %.

F polymers include polytetrafluoroethylene (PTFE), copolymers of TFE and ethylene (ETFE), copolymers of TFE and propylene, copolymers of TFE and perfluoro(alkyl vinyl ether) (PAVE) (PFA), copolymers of TFE and hexafluoropropylene (HFP) (FEP), copolymers of TFE and fluoroalkylethylene (FAE), and copolymers of TFE and chlorotrifluoroethylene (CTFE). The copolymers may further contain units based on other comonomers.
In addition, examples of PTFE include high molecular weight PTFE, low molecular weight PTFE, and modified PTFE having fibrillation properties. In addition, the low molecular weight PTFE and modified PTFE also include copolymers of TFE and a very small amount of comonomer (HFP, PAVE, FAE, etc.).

The F polymer preferably has TFE units and a functional group, preferably a carbonyl-containing group, a hydroxy group, an epoxy group, an amide group, an amino group or an isocyanate group.
The functional group may be contained in a unit in the F polymer or in a terminal group of the main chain of the polymer. In addition, an F polymer having a functional group obtained by subjecting an F polymer to a plasma treatment or ionizing radiation treatment can also be used.
From the viewpoint of dispersibility of F powder in the composition (1), the F polymer having functional group is preferably the F polymer having TFE unit and the unit having functional group.The unit having functional group is preferably the unit based on the monomer having functional group, and more preferably the unit based on the monomer having functional group described above.

The monomer having a functional group is preferably a monomer having an acid anhydride residue, and more preferably itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride (also called himic anhydride; hereinafter also referred to as "NAH"), or maleic anhydride.
A specific preferred example of the F polymer having a functional group is an F polymer having a TFE unit, an HFP unit, a PAVE unit or an FAE unit, and a unit having a functional group.
Examples of PAVE include _CF2 = _CFOCF3 (PMVE), _CF2 = _CFOCF2CF3 , _{and CF2} = _CFOCF2CF2CF3 ( _PPVE ) _.
Examples of FAE include _CH2 =CH( _{CF2 ) 2F} , CH2=CH( _CF2 ) _3F , _CH2 =CH( _CF2 ) _4F , _CH2 =CF( _CF2 ) _3H , and _CH2 =CF( _CF2 ) _4H .

Specific examples of such F polymers include F polymers containing 90 to 99 mol% TFE units, 0.5 to 9.97 mol% HFP units, PAVE units or FAE units, and 0.01 to 3 mol% units having functional groups, based on the total units constituting the polymer. Specific examples of such F polymers include the polymers described in WO 2018/16644.

The F polymer is preferably heat meltable.
The melt viscosity of the F polymer at 380° C. is preferably from 1×10 ² to 1×10 ⁶ Pa·s, and more preferably from 1×10 ³ to 1×10 ⁶ Pa·s.
The melting temperature of the F polymer is preferably 200 to 320° C., more preferably 260 to 320° C. By using such an F polymer, a dense layer (coating film) having excellent adhesion is easily formed. In addition, during heating in forming the layer (coating film), the F polymer and the binder resin flow to a high degree, and the physical properties of the layer (coating film) are easily improved.

The D50 of the F powder in the composition (1) is preferably 0.05 to 8 μm, more preferably 0.1 to 6.0 μm, and even more preferably 0.2 to 3.0 μm.
The D90 of the F powder is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. With D50 and D90 in this range, the fluidity and dispersibility of the F powder are good, and the electrical properties and heat resistance of the layer (coating film) are more easily exhibited.
The F powder may contain a resin other than the F polymer, but preferably contains the F polymer as a main component, and more preferably consists of the F polymer. The content of the F polymer in the powder is preferably 80% by mass or more, and more preferably 100% by mass.
Examples of the resin include aromatic polyester, polyamideimide, thermoplastic polyimide, polyphenylene ether, and polyphenylene oxide.

The liquid dispersion medium in the present composition (1) is a liquid that disperses the F powder, is inactive at 25° C., and does not react with the F powder, and is a liquid (compound) that dissolves the binder resin. The liquid dispersion medium is preferably a liquid that has a lower boiling point and is more volatile than the components other than the liquid dispersion medium contained in the present composition (1). The liquid dispersion medium may be used alone or in combination of two or more to form a mixed liquid dispersion medium.
The liquid dispersion medium may be a polar liquid dispersion medium or a non-polar liquid dispersion medium, with a polar liquid dispersion medium being preferred.
The liquid dispersion medium may be aqueous or non-aqueous, preferably non-aqueous.
The boiling point of the liquid dispersion medium is preferably 80 to 275° C., more preferably 125 to 250° C. Within this range, when the liquid dispersion medium is evaporated from the present composition (1) to form a layer (coating film), the F powder flows effectively and dense packing tends to progress.

Specific examples of liquid dispersion media include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, N,N-dimethylformamide, N,N-dimethylacetamide, methyl ethyl ketone, N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, cyclopentanone, dimethyl sulfoxide, diethyl ether, dioxane, ethyl lactate, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isopropyl ketone, cyclopentanone, cyclohexanone, ethylene glycol monoisopropyl ether, and cellosolve (methyl cellosolve, ethyl cellosolve, etc.).

The liquid dispersion medium in composition (1) is preferably an organic liquid (organic compound) from the viewpoint of adjusting the liquid properties (viscosity, thixotropy ratio, etc.) of composition (1) and the solubility of the binder resin, and is more preferably a ketone or amide from the viewpoint of the dispersion stability of composition (1), and is even more preferably methyl ethyl ketone, cyclohexanone or N-methyl-2-pyrrolidone.

The 20% weight loss temperature of the binder resin in the present composition (1) is 260°C or higher, preferably 300°C or higher, and more preferably 320°C or higher. The 20% weight loss temperature of the binder resin is preferably 600°C or lower. The 5% weight loss temperature of the binder resin is preferably 260°C or higher, more preferably 300°C or higher, and even more preferably 320°C or higher. The 5% weight loss temperature of the binder resin is preferably 600°C or lower. Within this range, the interface roughness of the layer (coating film) due to the decomposition gas (bubbles) of the binder resin and the gas (bubbles) that is a by-product associated with the reaction of the binder resin itself can be effectively suppressed, and the adhesion of the layer (coating film) is further improved.

The binder resin in the present composition (1) is a polymer soluble in a liquid dispersion medium. Such a binder resin enhances the interaction with other components (F polymer, liquid dispersion medium) in the present composition (1), and the dispersibility of the present composition (1) is likely to be improved. Furthermore, during heating in the formation of a layer (coating), the fluidity of the binder resin increases, and a highly uniform matrix is likely to be formed. As a result, it is considered that a layer (coating) with high adhesion to the substrate is formed while the original physical properties of the F polymer, such as electrical properties, are expressed as they are. In particular, when the content of the binder resin in the present composition (1) is low (particularly when the mass ratio of the content of the binder resin to the content of the F polymer is low), such an effect is likely to be further enhanced.

The binder resin in the composition (1) is an aromatic polyamideimide or an aromatic polyimide, and more preferably an aromatic polyimide.
The binder resin may be a non-reactive resin or a reactive resin.
The non-reactive resin means a polymer that does not have a reactive group that undergoes a reaction under the conditions of use of the present composition (1). For example, the non-reactive aromatic polyimide means an aromatic polyimide in which imidization has already been completed and no further imidization reaction occurs.
On the other hand, the reactive resin means a polymer that has the reactive group and undergoes a reaction (condensation reaction, addition reaction, etc.) under the conditions of use of the present composition (1). For example, the reactive aromatic polyimide means a polymer that is a precursor of an aromatic polyimide (such as a polyimide in which a partial imidization reaction of a polyamic acid or the like has progressed) and further undergoes an imidization reaction under the conditions of use of the present composition (such as heating).

The binder resin may be either thermoplastic or thermosetting.
If the binder resin is thermoplastic, the fluidity of the binder resin is enhanced during heating when forming a layer (coating film) from the present composition (1), a dense and uniform polymer layer is formed, and the adhesion of the layer (coating film) is likely to be improved. The thermoplastic binder resin is preferably a non-reactive thermoplastic resin.
The glass transition point of the thermoplastic binder resin is preferably 500° C. or lower. The glass transition point is preferably 0° C. or higher, and more preferably 200° C. or higher. Within this range, the fluidity of the binder resin and the dense packing of the F powder are likely to be enhanced in the formation of a layer (coating film).
On the other hand, if the binder resin is thermosetting, the layer (coating film) contains a cured product thereof, which further reduces the linear expansion property of the layer (coating film), and the occurrence of warping is more easily suppressed. The thermosetting binder resin is preferably a reactive thermosetting resin.
The binder resin is preferably a non-reactive thermoplastic resin or a reactive thermosetting resin, and more preferably a non-reactive thermoplastic resin.

Specific examples of binder resins include polyamide-imide resins such as the "HPC" series (manufactured by Hitachi Chemical Co., Ltd.), and polyimide resins such as the "Neoprim" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), "Spiccellia" series (manufactured by Somar), "Q-PILON" series (manufactured by PI Technical Research Institute), "WINGO" series (manufactured by Wingo Technology Co., Ltd.), "Tomide" series (manufactured by T&K Toka Corporation), "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.), and "Upia-AT" series (manufactured by Ube Industries, Ltd.).

A suitable embodiment of the F polymer and binder resin in the composition (1) is one in which the F polymer is a heat-fusible F polymer and the glass transition point of the binder resin is equal to or lower than the melting temperature of the F polymer. In this case, the melting temperature of the F polymer is preferably 260 to 320°C, more preferably 280 to 320°C. The glass transition point of the binder resin is preferably 80 to 320°C, more preferably 150 to 320°C, and even more preferably 180 to 300°C.

In the above embodiment, when the composition (1) is heated to form a polymer layer, the F polymer melts and the binder resin is likely to soften. As a result, the F polymer and the binder resin flow mutually to a high degree, and the physical properties of each are likely to be significantly expressed in the formed polymer layer. For example, since the binder resin is an aromatic polymer, the UV absorption of the polymer layer is also likely to be improved. In addition, if the F polymer is an F polymer (PFA) having TFE units and PAVE units, particularly an F polymer having TFE units, PAVE units, and functional groups, a polymer-layered metal foil with improved electrical properties is likely to be obtained. If such a polymer-layered metal foil is processed using a UV-YAG laser with a wavelength of 355 nm or the like, a printed circuit board suitable for transmitting high-frequency signals can be efficiently manufactured.

From the viewpoint of promoting the dispersion of the F powder in the composition (1) and the interaction with the binder resin, and improving the formability of the layer (coating film), it is preferable that the composition (1) further contains a surfactant. The surfactant is a component (compound) different from both the F polymer and the binder resin.
The surfactant is preferably a nonionic surfactant having a hydrophilic portion and a hydrophobic portion.
The hydrophilic portion is preferably a molecular chain containing a nonionic functional group (an alcoholic hydroxyl group, a polyoxyalkylene group, etc.).
The hydrophobic portion is preferably a molecular chain containing a lipophilic group (an alkyl group, an acetylene group, etc.), a polysiloxane group, or a fluorine-containing group, and more preferably a molecular chain containing a fluorine-containing group.
A preferred embodiment of the surfactant is a surfactant having a perfluoroalkyl group or a perfluoroalkenyl group and a polyoxyalkylene group or an alcoholic hydroxyl group on the side chain.

The surfactant is preferably nonionic.
The weight average molecular weight of the surfactant is preferably from 2,000 to 80,000, and more preferably from 6,000 to 20,000.
The fluorine content of the surfactant is preferably from 10 to 60% by mass, more preferably from 20 to 50% by mass.
When the surfactant has an oxyalkylene group, the content of the oxyalkylene group in the surfactant is preferably from 10 to 60% by mass, and more preferably from 20 to 50% by mass.
When the surfactant has an alcoholic hydroxyl group, the hydroxyl value of the surfactant is preferably from 10 to 300 mgKOH/g.

The number of carbon atoms in the perfluoroalkyl group or perfluoroalkenyl group is preferably from 4 to 16. In addition, an ether oxygen atom may be inserted between carbon atoms in the perfluoroalkyl group or perfluoroalkenyl group.
The polyoxyalkylene group may be composed of one type of polyoxyalkylene group or two or more types of polyoxyalkylene groups, in which case the different types of polyoxyalkylene groups may be arranged randomly or in blocks.
The polyoxyalkylene group is preferably a polyoxyethylene group or a polyoxypropylene group, and more preferably a polyoxyethylene group.
Specific preferred examples of the surfactant include copolymers of a (meth)acrylate having a perfluoroalkyl group or a perfluoroalkenyl group and a (meth)acrylate having a polyoxyalkylene group or an alcoholic hydroxyl group.

Specific examples of the former (meth)acrylate include _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _{CF2 ) 4F} , _CH2 =CHC(O) _OCH2CH2 ( _CF2 ) _6F , _CH2 =C _{( CH3} )C(O _{) OCH2CH2} (CF2) _{6F , CH2} =CHC(O) _OCH2CH2OCF ( _CF3 )C(=C( _CF3 ) ₂ )(CF( _CF3 ) _{2 )} , _CH2 =C( _{CH3 )} C(O)OCH2CH2OCF( _CF3 )C(=C( _CF3 ) ₂ )(CF( _CF3 ) ₂ ), _CH2 =CHC(O) _{OCH 2CH2CH2CH2OCF} ( _CF3 )C(=C( _CF3 ) ₂ )(CF( _CF3 ) _{2 )} , _CH2 =C _{( CH3} )C(O)OCH2CH2CH2CH2OCF( _CF3 )C(=C( _CF3 ) ₂ ) ₍ CF _{( CF3} ) ₂ ), _CH2 =C( _CH3 )C(O _{) CH2CF2} ( _OCF2 ) _{f1 .} ( _OCF2CF2 ) _f2OCF3 (where _{f1 and f2} in the formula are natural numbers and the sum is ₂₀ ).

Specific examples of the latter (meth)acrylate include _CH2 =C( _CH3 ) _C (O)OCH2CH2OH, _CH2 =C(CH3)C(O) _{OCH2CH2CH2CH2OH} , _CH2 =C _{( CH3} ) _C (O)( _OCH2CH2 ) _4OH , _CH2 =C( _{CH3 )} C(O ₎ ( _OCH2CH2 ) _{9OH ,} CH2 ₌ C _{( CH3 )} C(O ₎ ( _OCH2CH2 ) _{23OH , CH2} =C( _CH3 )C ₍ O)( _OCH2CH2 ) _9OCH3 , _CH2 =C _{( CH3} )C _{( O} )(OCH2CH2) _{23 ... Examples} include ═C( _CH3 )C(O)( _{OCH2CH2 ) 66OCH3 and CH2═C ( CH3} )C(O)( _OCH2CH2 ) _120OCH3 .
Specific examples of surfactants include the "Ftergent" series (manufactured by Neos), the "Surflon" series (manufactured by AGC Seimi Chemical Co., Ltd.), the "Megafac" series (manufactured by DIC Corporation), and the "Unidyne" series (manufactured by Daikin Industries, Ltd.).

The composition (1) may contain a thixotropy imparting agent, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a brightening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, a viscosity adjusting agent, or a flame retardant, as long as the effects of the present invention are not impaired.
The viscosity of the present composition (1) at 25° C. is preferably 10,000 mPa·s or less, more preferably 50 to 5,000 mPa·s, and even more preferably 100 to 1,000 mPa·s. In this case, the present composition (1) tends to have excellent liquid properties (dispersibility and coatability) and compatibility with different materials.
The thixotropy ratio of the present composition (1) is preferably from 1 to 2.5, and more preferably from 1.2 to 2. In this case, not only is the present composition (1) excellent in liquid physical properties, but the homogeneity of the layer (coating film) is also likely to be improved.

The content (proportion) of the F polymer in the composition (1) is preferably 5 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 30 to 45% by mass. Within this range, a layer (coating film) having excellent electrical properties and substrate adhesion is easily formed.
The content (proportion) of the binder resin in the composition (1) is preferably 1% by mass or less, more preferably 0.5% by mass or less, and is preferably 0.01% by mass or more.
In the present composition (1), the mass ratio of the binder resin content to the F polymer content is preferably 0.05 or less, more preferably 0.02 or less, and even more preferably 0.01 or less. The above ratio is preferably 0.001 or more. When the binder resin content and the F polymer content are within this range, the dispersibility of the present composition (1) is more easily improved without impairing the original physical properties of the F polymer in the layer (physical properties).
When the present composition (1) contains a surfactant, the content (ratio) of the surfactant in the present composition (1) is preferably 1 to 15 mass%, more preferably 3 to 10 mass%. In this case, the mass ratio of the content of the surfactant to the content of the F polymer is preferably 0.01 to 0.25, more preferably 0.05 to 0.15. In this range, the physical properties of the layer (coating film) are more likely to be improved.

The composition (1) is useful as a coating agent for forming a layer (coating film) containing an F polymer on the surface of a substrate.
The material of the substrate is not particularly limited, but glass or metal is preferable.
The shape of the substrate is not particularly limited, and may be any shape such as a plate, a sphere, or a fiber.
The thickness of the layer (coating film) to be formed is not particularly limited, but is preferably 0.1 to 1000 μm.
By using the present composition (1), it is possible to obtain a layer, coating film, or molded product that has excellent adhesion and fully exhibits the inherent physical properties of the F polymer, regardless of the material and shape of the substrate, the thickness of the layer (coating film), etc.

The present composition (1) can be used for producing molded articles such as films, impregnated articles (prepregs, etc.), and laminates (metal laminates such as polymer-layered metal foils), as well as for producing molded articles for applications requiring releasability, electrical properties, water and oil repellency, chemical resistance, weather resistance, heat resistance, slipperiness, abrasion resistance, etc.
The obtained molded products are useful as antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, paints, cosmetics, etc., and specifically, are useful as electric wire covering materials (aircraft electric wires, etc.), electrical insulating tapes, insulating tapes for oil drilling, materials for printed circuit boards, separation membranes (microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, dialysis membranes, gas separation membranes, etc.), electrode binders (for lithium secondary batteries, for fuel cells, etc.), copy rolls, furniture, automobile dashboards, covers for home appliances, sliding members (load bearings, sliding shafts, valves, bearings, gears, cams, belt conveyors, food transport belts, etc.), tools (shovels, files, saws, saws, etc.), boilers, hoppers, pipes, ovens, baking molds, chutes, dies, toilets, and container covering materials.

This composition (1) is applied to the surface of a metal foil (hereinafter also referred to as "metal foil F") having a ten-point average roughness of 0.5 μm or less, and heated to a temperature of 260° C. or higher to form a polymer layer (hereinafter also referred to as "F layer") containing an F polymer on the surface of the metal foil F, thereby producing a metal foil with a polymer layer having the metal foil F and the F layer in this order.
In such a polymer layer-attached metal foil, the metal foil F and the F layer have high adhesion, and further, peeling, swelling, and warping are highly suppressed when heated during processing (for example, heating in a solder reflow process during processing of the polymer layer-attached metal foil). The reason for this is not necessarily clear, but is thought to be as follows.

The composition (1) contains a binder resin whose weight loss rate is in a predetermined low range in the high temperature region where the F polymer is baked. As a result, it is considered that the roughness of the interface of the F layer caused by residues due to the decomposition of the binder resin and by-products due to the reaction of the binder resin that may occur during baking is suppressed, and the metal foil F with high surface smoothness and the F layer are highly adhered to each other.
Furthermore, since the thickness of the F layer is within a predetermined range and the thermal expansion of the F layer is also suppressed, it is believed that the occurrence of swelling and warping due to heating is suppressed, and a metal foil with a polymer layer having excellent electrical properties is obtained.

The ten-point average roughness of the surface of the metal foil F is 0.5 μm or less, preferably 0.2 μm or less, and more preferably less than 0.1 μm. The ten-point average roughness of the surface of the metal foil F is preferably 0.01 μm or more.
Examples of the material for the metal foil F include copper, copper alloys, stainless steel, nickel, nickel alloys (including alloy 42), aluminum, aluminum alloys, titanium, and titanium alloys.
The metal foil F is preferably a rolled copper foil or an electrolytic copper foil.
The surface of the metal foil F may be subjected to an anti-rust treatment (such as an oxide film of chromate). The surface of the metal foil F may also be treated with a silane coupling agent. In this case, the entire surface of the metal foil F may be treated with the silane coupling agent, or only a part of the surface of the metal foil F may be treated with the silane coupling agent.
The thickness of the metal foil F is preferably 0.1 to 20 μm, more preferably 1 to 20 μm, and even more preferably 2 to 5 μm.

In addition, a carrier-attached metal foil containing two or more layers of metal foil may be used as the metal foil F. Examples of carrier-attached metal foils include carrier-attached copper foils consisting of a carrier copper foil (thickness: 10 to 35 μm) and an ultra-thin copper foil (thickness: 2 to 5 μm) laminated on the carrier copper foil via a release layer. By peeling off only the carrier copper foil of such a carrier-attached copper foil, a metal clad laminate having an ultra-thin copper foil can be easily formed. By using this metal clad laminate, it is possible to form a fine pattern by using the MSAP (modified semi-additive) process, using the ultra-thin copper foil layer as a plating seed layer.
From the viewpoint of heat resistance, the release layer is preferably a metal layer containing nickel or chromium, or a multi-layer metal layer formed by laminating such metal layers. With such a release layer, the carrier copper foil can be easily peeled off from the ultra-thin copper foil even after a process at 300° C. or higher.
A specific example of the metal foil with a carrier is "FUTF-5DAF-2" manufactured by Fukuda Metal Foil & Powder Co., Ltd.

The F layer may contain an inorganic filler and an organic component other than the F polymer and the binder resin, as long as the effect of the present invention is not impaired.
The thickness of the F layer is preferably 0.1 μm or more, more preferably 1 μm or more. The thickness of the F layer is preferably less than 10 μm, more preferably 8 μm or less, and even more preferably 5 μm or less. A preferred embodiment of the thickness of the F layer is 1 to 5 μm.
Even in such a configuration, the composition (1) can provide a polymer-layered metal foil having a low roughness metal foil (metal foil F) with high surface smoothness and a thin-film polymer layer (F layer) that does not impair the original physical properties of the F polymer (low dielectric constant, low dielectric tangent, low water absorption, etc.), in that order, with the two firmly adhered to each other, thereby suppressing problems during heating.
The ratio of the thickness of the F layer to the thickness of the metal foil F is preferably 0.1 to 5.0, more preferably 0.2 to 2.5. If the ratio of the thicknesses of the two is within this range, the transmission characteristics as a printed circuit board are further improved.

The method for applying the composition (1) may be any method that can form a stable liquid coating (wet film) on the surface of the metal foil, and examples of such methods include spraying, roll coating, spin coating, gravure coating, microgravure coating, gravure offset, knife coating, kiss coating, bar coating, die coating, fountain-meyer bar, slot die coating, and comma coating.
After application of the composition (1), it is preferable to heat the composition to a temperature lower than the above temperature before heating to a temperature of 260° C. or higher to remove the liquid dispersion medium in the wet film. The heating temperature may be set according to the boiling point of the liquid dispersion medium, and is preferably 90 to 250° C., more preferably 100 to 200° C. In addition, the heating may be performed in one step, or in two or more steps at different temperatures. Furthermore, the heating time in this case is preferably 0.1 to 10 minutes, more preferably 0.5 to 5 minutes.

The temperature of 260°C or more applied after application of the present composition (1) is preferably a temperature at which the F polymer is baked. The temperature at this time may be set according to the type of F polymer, and is preferably 300 to 400°C, more preferably 310 to 390°C, and even more preferably 320 to 380°C. Furthermore, the heating at this time may be performed in one stage, or in two or more stages at different temperatures. Furthermore, the heating time at this time is preferably 1 to 60 minutes, more preferably 3 to 20 minutes.
The means for heating the two include a method using an oven, a method using a ventilated drying furnace, and a method using heat rays such as infrared rays.
The atmosphere in which the two are heated may be either under normal pressure or under reduced pressure. The atmosphere may be any of an oxidizing gas (oxygen gas, etc.), a reducing gas (hydrogen gas, etc.), and an inert gas (helium gas, neon gas, argon gas, nitrogen gas, etc.), and is preferably an inert gas atmosphere from the viewpoint of suppressing decomposition of the binder resin.

A preferred embodiment of the method for producing a metal foil with a polymer layer is to use the composition (1) in which the F polymer is a thermally fusible F polymer and the binder resin is a binder resin with a glass transition point below the melting temperature of the F polymer, and to bake the F polymer at a temperature equal to or higher than the melting temperature. In this embodiment, the F polymer melts, the binder resin softens, and the F layer is easily formed through a state in which the two are highly mutually fluidized. As a result, the physical properties of each polymer are easily manifested in the F layer of the formed metal foil with a polymer layer. For example, if the binder resin is an aromatic polymer (such as an aromatic polyimide), not only is the adhesiveness and heat resistance excellent, but the UV absorption of the F layer is also easily improved. In addition, if the F polymer is an F polymer (PFA) having TFE units and PAVE units, especially an F polymer having TFE units, PAVE units, and functional groups, the electrical properties are more easily improved. According to this preferred embodiment of the method for producing a metal foil with a polymer layer, a printed circuit board suitable for transmitting high-frequency signals can be efficiently produced.

The outermost surface of the F layer of the polymer layer-coated metal foil may be subjected to a surface treatment in order to further improve its thermal expansion properties and adhesiveness.
Examples of the surface treatment method include annealing treatment, corona treatment, plasma treatment, ozone treatment, excimer treatment, and silane coupling treatment.
The conditions for the annealing treatment 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.
As a plasma irradiation device for the plasma treatment, a high frequency induction type, a capacitively coupled electrode type, a corona discharge electrode-plasma jet type, a parallel plate type, a remote plasma type, an atmospheric pressure plasma type, or an ICP type high density plasma type can be used.
Examples of gases used in the plasma treatment include oxygen gas, nitrogen gas, rare gas (such as argon), hydrogen gas, ammonia gas, and vinyl acetate. These gases may be used alone or in combination of two or more to form a mixed gas.

On the outermost surface of the F layer of the polymer layer-coated metal foil, another substrate may be further laminated.
Other substrates include a heat-resistant resin film, a prepreg which 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.
Note that a prepreg is a sheet-like substrate in which a base material (tow, woven fabric, etc.) of reinforcing fibers (glass fibers, carbon fibers, etc.) is impregnated with a thermosetting resin or a thermoplastic resin.
The heat-resistant resin film is a film containing one or more types of heat-resistant resin, and may be a single-layer film or a multi-layer film.
Examples of the heat-resistant resin include polyimide, polyarylate, polysulfone, polyarylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystalline polyester, and liquid crystalline polyesteramide.

The bonding method may be a method of hot pressing the laminate and another substrate.
When the other substrate is a prepreg, the heat pressing conditions are preferably a temperature of 120 to 300° C., a reduced atmospheric pressure (vacuum) of 20 kPa or less, and a pressing pressure of 0.2 to 10 MPa. When the other substrate is a heat-resistant resin film, the heat pressing conditions are preferably a temperature of 310 to 400° C.
The polymer layer-attached metal foil formed from the composition (1) has a thin-film F layer and a low-roughening metal foil, which are excellent in physical properties such as electrical properties, chemical resistance (etching resistance), and heat resistance, as described above. Such a polymer layer-attached metal foil can be used as a flexible metal-clad laminate or a rigid metal-clad laminate for the manufacture of a printed circuit board, and can be particularly suitably used as a flexible metal-clad laminate for the manufacture of a flexible printed circuit board.

A printed circuit board is obtained by etching the metal foil F of the polymer layer-attached metal foil to form a transmission circuit. Specifically, a printed circuit board can be manufactured from the polymer layer-attached metal foil obtained by the above-mentioned manufacturing method by a method of processing the metal foil F into a predetermined transmission circuit by etching the metal foil F or a method of processing the metal foil F into a predetermined transmission circuit by electrolytic plating (semi-additive method (SAP method), modified semi-additive method (MSAP method), etc.).
A printed circuit board produced from a polymer layer-coated metal foil formed from the composition (1) has a transmission circuit and an F layer, in this order, formed from metal foil F. Specific examples of the configuration of the printed circuit board include transmission circuit/F layer/prepreg layer and transmission circuit/F layer/prepreg layer/F layer/transmission circuit.
In the manufacture of a printed circuit board, an interlayer insulating film may be formed on a transmission circuit, a solder resist may be laminated on the transmission circuit, or a coverlay film may be laminated on the transmission circuit. The composition (1) may be used as a material for these interlayer insulating films, solder resists, and coverlay films.

A specific embodiment of the printed circuit board produced from the polymer-layered metal foil is a multilayer printed circuit board obtained by multilayering the printed circuit boards obtained by the present invention.
A preferred embodiment of the multilayer printed circuit board is one in which the outermost layer of the multilayer printed circuit board is an F layer, and the multilayer printed circuit board has one or more structures in which a metal foil F or a transmission circuit, an F layer, and a prepreg layer are laminated in this order. The number of the above structures is preferably two or more. A transmission circuit may be further disposed between the F layer and the prepreg layer.
The multilayer printed circuit board of this embodiment has particularly excellent heat resistance and processability due to the outermost F layer. Specifically, even at 288° C., there is little interfacial swelling between the F layer and the prepreg layer, and little interfacial peeling between the metal foil F (transmission circuit) and the F layer. In particular, even when the metal foil F forms a transmission circuit, the F layer is thin and tightly adheres to the metal foil (transmission circuit), so warping is unlikely to occur and the heat resistance and processability are excellent.

A preferred embodiment of the multilayer printed circuit board is one in which the outermost layer of the multilayer printed circuit board is a prepreg layer, and the multilayer printed circuit board has one or more structures in which a metal foil F or a transmission circuit, an F layer, and a prepreg layer are laminated in this order. The number of the above structures is preferably two or more. A transmission circuit may be further disposed between the F layer and the prepreg layer.
The multilayer printed circuit board of this embodiment has excellent heat resistance and processability even if it has a prepreg layer as the outermost layer. Specifically, even at 300° C., the F layer and the prepreg layer do not easily bulge at the interface, and the metal foil F (transmission circuit) and the F layer do not easily peel off at the interface. In particular, even if the metal foil F forms a transmission circuit, the F layer is thin and is firmly attached to the metal foil (transmission circuit), so that the F layer is unlikely to warp and has excellent heat resistance and processability.
In other words, by using the composition (1), it is possible to easily obtain printed circuit boards having various configurations in which the respective interfaces are firmly adhered to each other without the need for various surface treatments, and in which the occurrence of interfacial blistering or interfacial peeling due to heating, particularly blistering or peeling in the outermost layer, is suppressed.

A second embodiment of the present composition (hereinafter also referred to as the present composition (2)) includes an embodiment containing F powder, an aromatic polyimide having an imidization rate of 1% or more, and an aprotic polar liquid dispersion medium.
Composition (2) has excellent dispersibility of F powder. The reason for this is not entirely clear, but is thought to be as follows.

The aromatic polyimide in composition (2) is not a polyamic acid (imidization rate: 0%), which is a polyimide precursor in which imidization has not progressed substantially, but a polyimide in which the imidization reaction between the carboxylic acid dianhydride and the diamine constituting the polymer has progressed to a predetermined ratio (imidization rate: 1% or more; hereinafter, also referred to as "PI(2)").
In such polyimides, imide groups are formed (ring closure) during the imidization reaction, and thus the polarity (dissociable protons) is reduced. It is believed that such polyimides tend to have lower solubility (or dispersibility) in a liquid dispersion medium, while their affinity with the F polymer tends to increase.

As a result of intensive research, the inventors have found that the use of PI (2) has an effect of increasing affinity with the F polymer, rather than a decrease in solubility (or dispersibility) in the liquid dispersion medium. It is believed that PI (2) acts as a dispersant for the F polymer, promoting the dispersion of the powder and improving the dispersibility of the entire liquid composition. Furthermore, it is believed that the inclusion of such PI (2) maintains the viscosity or thixotropy of the liquid composition, suppressing the settling, aggregation, and phase separation of each component.
As a result, in a molded article (such as an F layer (coating film)) formed from this composition (2), it is believed that the physical properties of each polymer are highly expressed due to the high level of interaction between the F polymer and PI (2). For example, since the molded article contains PI (2), it has a low linear expansion coefficient, and therefore is less likely to warp and has excellent adhesion and bonding properties. In addition, the aromatic ring in PI (2) has good UV absorption properties, so it is also excellent in processability with a UV-YAG laser or the like. And, since the molded article contains the F polymer, the physical properties of the F polymer (particularly electrical properties such as low dielectric constant and low dielectric tangent) are highly expressed.
The above-mentioned effects are more pronounced in the preferred embodiments of the present composition (2) described below.

The definitions of the F polymer and the F powder in the present composition (2), including preferred embodiments, are the same as those in the present composition (1). The F polymer in the present composition (2) is preferably a PFA containing TFE units and PAVE units and having a melting temperature of 260 to 320°C.
The D50 of the F powder in the composition (2) is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 3 μm or less. The D50 of the F powder is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 1 μm or more.
Furthermore, the D90 of the F powder is preferably 40 μm or less, more preferably 10 μm or less. With D50 and D90 in this range, the flowability and dispersibility of the F powder are good, and the electrical properties (low dielectric constant, etc.) and heat resistance of the resulting molded product are most easily exhibited.
The loosely packed bulk density of the F powder is preferably 0.08 to 0.5 g/mL. The densely packed bulk density of the F powder is preferably 0.1 to 0.8 g/mL. When the loosely packed bulk density or the densely packed bulk density is within the above range, the F powder has excellent handleability.

The F powder may contain components other than the F polymer, but is preferably made of the F polymer. The content of the F polymer in the F powder is preferably 80% by mass or more, and more preferably 100% by mass.
Examples of components other than the F polymer include aromatic polyesters, polyamideimides, thermoplastic polyimides, polyphenylene ethers, and polyphenylene oxides.

The PI (2) in the composition (2) is an aromatic polyimide having an imidization rate of 1% or more.
PI(2) is a unit based on a carboxylic dianhydride and a diamine, and has a unit (a unit having an imide structure; hereinafter, also referred to as an "imide unit") formed by an imidization reaction between the two compounds. At least one of the carboxylic dianhydride and the diamine, and at least a part of the unit, is an aromatic compound.
PI (2) may be composed of only imide units, or may have imide units and units formed by an amidation reaction of the above-mentioned two compounds (units having an amic acid structure; hereinafter, also referred to as "amic acid units"). In addition, the carboxylic acid dianhydride and the diamine may each be one type of compound, or a plurality of compounds may each be used. As the carboxylic acid dianhydride, it is preferable to use at least one type of aromatic carboxylic acid dianhydride.

The imidization ratio in PI(2) is the ratio of the number of moles of imide units to the total number of moles of amic acid units and imide units, that is, the value calculated by the formula: number of moles of imide units/(number of moles of amic acid units+number of moles of imide units). In other words, when PI(2) is composed only of imide units, the imidization ratio is 100%.
The lower limit of the imidization rate is preferably 10% or more, more preferably 25% or more, even more preferably 50% or more, and particularly preferably 75% or more. If the imidization rate is within this lower limit range, the polarity (dissociable protons) of PI (2) is further reduced, and the dispersibility of the F polymer is more easily promoted.

The upper limit of the imidization rate is preferably less than 100%, more preferably 98% or less, and even more preferably 96% or less. If the imidization rate is within this upper limit range, PI (2) can promote interaction with each component (liquid dispersion medium and F polymer) while sufficiently maintaining its polarity (dissociable protons), and the physical properties (viscosity, thixotropy, etc.) of the liquid composition can be more easily improved.
The imidization ratio of PI (2) can be controlled by the production conditions. For example, by using a dehydration apparatus such as a Dean-Stark apparatus, a carboxylic acid dianhydride and a diamine are reacted in the presence of a liquid dispersion medium (e.g., toluene) that forms an azeotropic mixture with water while removing the by-product water, PI (2) with any imidization ratio can be produced.
The imidization rate of PI(2) can be measured by subjecting PI(2) to NMR analysis.

PI (2) preferably contains units based on an aromatic tetracarboxylic acid dianhydride and an aromatic diamine or an aliphatic diamine having a linking structure in which two or more arylene groups are linked via a linking group. Such PI (2) tends to have a higher affinity with F polymer, and not only increases the dispersibility of the composition (2), but also tends to improve the adhesion of molded articles formed therefrom. In other words, such PI (2) tends to function both as a dispersant in the composition (2) and as an adhesive component in molded articles.

The aromatic tetracarboxylic acid dianhydride is preferably a compound represented by the following formulae AN1 to AN6.

The linking structure in the aromatic diamine is preferably a structure in which 2 to 4 arylene groups are linked together, in which case the polarity of PI(2) is balanced, making it easier to exhibit the above tendency.
The arylene group is preferably a phenylene group, in which a hydrogen atom may be substituted with a hydroxyl group, a fluorine atom or a trifluoromethyl group.
The linking group in the aromatic diamine is preferably an ethereal oxygen atom, a propane-2,2-diyl group, or a perfluoropropane-2,2-diyl group. The linking group may be one type or two or more types, and it is more preferable that the linking group is an ethereal oxygen atom. In this case, PI(2) is more likely to exhibit the above tendency due to its steric effect.

The aromatic diamine is preferably a compound represented by the following formulae DA1 to DA6.

Examples of aliphatic diamines include dimer diamines, alkylenediamines (2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 2,7-dimethyl-1,8-octanediamine, etc.), and alicyclic diamines (1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, 2,2-bis(4-aminocyclohexyl)hexafluoropropane, isophoronediamine, and norbornanediamine).
Dimer diamine is a compound in which two carboxyl groups of a dimer acid, which is a dimer of an unsaturated fatty acid, are substituted with amino groups or aminomethyl groups. The unsaturated fatty acid is preferably an unsaturated fatty acid having 11 to 22 carbon atoms (oleic acid, linoleic acid, linolenic acid, etc.).
When an aliphatic amine is used, not only is the above tendency more likely to be exhibited, but the F polymer properties (particularly electrical properties such as dielectric constant and dielectric loss tangent) in the molded product are more likely to be highly expressed, and the flexibility is more likely to be improved.

Specific examples of commercially available dimer diamines include VERSAMINE 551 (manufactured by BASF Japan), VERSAMINE 552 (manufactured by BASF Japan, a hydrogenated product of VERSAMINE 551), PRIAMINE 1075 (manufactured by Croda Japan), and PRIAMINE 1074 (manufactured by Croda Japan).

In addition, as the carboxylic acid dianhydride constituting PI (2), a carboxylic acid dianhydride having an alicyclic structure as shown below may be used. If the unit contained in PI (2) contains such an alicyclic structure, the affinity between PI (2) and the liquid dispersion medium is increased, the dispersibility in the entire liquid composition is further improved, and the coatability of the liquid composition is also improved. In addition, coloring in a molded article formed therefrom is easily suppressed.

The aprotic polar liquid dispersion medium in the composition (2) is a liquid compound that is inactive at 25° C. and functions as a dispersion medium for the F powder.
The dispersion medium is preferably a compound having a lower boiling point and volatility than the components other than the liquid dispersion medium contained in the composition (2). The liquid dispersion medium may be used alone or in combination of two or more kinds.
The boiling point of such a liquid dispersion medium is preferably 125 to 250° C. In this case, when a liquid coating is formed from the present composition (2) by drying, the flow of the F powder proceeds effectively with the evaporation of the liquid dispersion medium, and the F powder is likely to be densely packed.

Specific examples of aprotic polar liquid dispersion media include N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, cyclopentanone, butyl acetate, methyl isopropyl ketone, cyclopentanone, and cyclohexanone.
Among these, from the viewpoint of adjusting the liquid properties (viscosity, thixotropy ratio, etc.) of the present composition (2), the aprotic polar liquid dispersion medium is preferably an amide or a ketone, and more preferably N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-methyl-2-pyrrolidone, or γ-butyrolactone.

The present composition (2) preferably contains a surfactant having a hydroxyl group and an oxyalkylene group as a hydrophilic portion (hereinafter, also referred to as "surfactant"). Surfactants having these groups have appropriate hydrophilicity (polarity), and therefore not only promote the dispersion of the powder in the present composition (2), but also increase the affinity between the polar PI (2) and the F polymer, and tend to further improve the dispersibility of the present composition (2) as a whole.
As such a surfactant, the surfactant in the present composition (1) is preferred.

The composition (2) preferably contains water at 50 ppm or more. A small amount of water is expected to enhance the affinity between the components contained in the composition (2). The water content is more preferably 100 ppm or more. The upper limit of the water content (ratio) in the composition (2) is preferably 5000 ppm or less, more preferably 1000 ppm or less.
The viscosity of the composition (2) is preferably 10,000 mPa·s or less, and more preferably 10 to 1,000 mPa·s.
The thixotropy ratio of the present composition (2) is preferably 1-2.

This composition (2) may contain other components, such as polymers other than F polymer and PI (2), inorganic fillers, thixotropic agents, defoamers, silane coupling agents, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, viscosity adjusters, and flame retardants, within the scope of the present invention.

The inorganic filler may be determined according to the properties to be imparted to the layer formed from the composition (2). The composition (2) contains PI (2), has excellent liquid properties (viscosity, thixotropy ratio, etc.), and has excellent dispersibility even when it contains an inorganic filler. In addition, when a layer is formed from the composition, not only is the inorganic filler less likely to fall off, but it is also easy to form a layer in which the inorganic filler is uniformly distributed.
Examples of inorganic fillers include nitride fillers and inorganic oxide fillers, and boron nitride fillers, beryllia (beryllium oxide), silica fillers, and metal oxide (cerium oxide, alumina, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.) fillers are preferred.

The shape of the inorganic filler may be granular, non-granular (scale-like, layer-like), or fibrous, and it is preferable for the inorganic filler to have a fine structure.
Specific examples of inorganic fillers having such a fine structure include spherical inorganic fillers and fibrous inorganic fillers.
The average particle size of the former inorganic filler is preferably 0.001 to 3 μm, more preferably 0.01 to 1 μm, in which case the inorganic filler has better dispersibility in the present composition (2) and is more likely to be distributed uniformly in the layer.
In the latter inorganic filler, the length is the fiber length and the diameter is the fiber diameter. The fiber length is preferably 1 to 10 μm, and the fiber diameter is preferably 0.01 to 1 μm.
When the present composition (2) contains an inorganic filler, the content thereof relative to the content of the F polymer is preferably 1 or less.

At least a portion of the surface of the inorganic filler may be surface-treated with an organic substance, an inorganic substance (however, the inorganic substance is different from the inorganic substance that forms the inorganic filler), or both.
Examples of organic substances used in such coating treatments include polyhydric alcohols (trimethylolethane, pentaerythritol, propylene glycol, etc.), saturated fatty acids (stearic acid, lauric acid, etc.), their esters, alkanolamines, amines (trimethylamine, triethylamine, etc.), paraffin wax, silane coupling agents, silicones, and polysiloxanes.
The inorganic substances used in such coating treatment include oxides, hydroxides, hydrated oxides, or phosphates of aluminum, silicon, zirconium, tin, titanium, antimony, and the like.

In order to further improve the UV processability of the layer formed from the present composition (2) while highly suppressing warping, the present composition (2) preferably contains a spherical inorganic filler.
In this case, the average particle size of the spherical inorganic filler is preferably smaller than the average particle size (D50) of the F powder. Specifically, the average particle size of the F powder is preferably 0.2 to 3 μm, and the average particle size of the spherical silica filler is preferably 0.01 to 0.1 μm. In addition, the content of the spherical inorganic filler in this case is preferably 0.01 to 0.1 relative to the content of the F polymer. With this configuration, it is possible to easily form a layer in which the inorganic filler is uniformly dispersed while suppressing exposure of the inorganic filler on the surface of the layer.

Specific examples of suitable inorganic fillers include silica fillers with an average particle size of 1 μm or less that have been surface-treated with an aminosilane coupling agent (such as the "Admafine" series manufactured by Admatechs Co., Ltd.), zinc oxide with an average particle size of 0.1 μm or less that has been surface-treated with an ester such as propylene glycol dicaprylate (such as the "FINEX" series manufactured by Sakai Chemical Industry Co., Ltd.), spherical fused silica with an average particle size of 0.5 μm or less and a maximum particle size of less than 1 μm (such as the SFP grade manufactured by Denka Co., Ltd.), rutile-type titanium oxide with an average particle size of 0.5 μm or less that has been coated with a polyhydric alcohol and an inorganic substance (such as the "Typeque" series manufactured by Ishihara Sangyo Co., Ltd.), and rutile-type titanium oxide with an average particle size of 0.1 μm or less that has been surface-treated with an alkylsilane (such as the "JMT" series manufactured by Teika Corporation).

The content (ratio) of the F polymer in the composition (2) is preferably equal to or greater than the content (ratio) of PI (2). In this case, the obtained molded article can be imparted with a good balance of properties based on the F polymer and properties based on PI (2), and the physical properties of the F polymer are easily expressed to a high degree.
Specifically, the content of the F polymer in the composition (2) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass. The content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. In this case, it is easy to form a molded product having excellent electrical properties and adhesion to a substrate.

The content of PI (2) in the composition (2) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more. The content is preferably 50% by mass or less, more preferably 25% by mass or less, and even more preferably 10% by mass or less. In this case, it is easy to form a molded product with improved UV processability.
The ratio of the content (proportion) of PI (2) to the content (proportion) of the F polymer in the composition (2) is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.1 or less.
The content (proportion) of the aprotic polar liquid dispersion medium in the composition (2) is preferably from 40 to 90 mass %, more preferably from 50 to 80 mass %.
When the present composition (2) contains a surfactant, the content (ratio) of the surfactant in the present composition (2) is preferably 1 to 15 mass %, in which case the inherent physical properties of the F polymer in the molded article are more likely to be improved.

This composition (2) is applied to the surface of a substrate and heated to form a polymer layer (F layer) containing an F polymer, thereby obtaining a laminate having the substrate and the F layer in this order.
In the manufacture of such a laminate, the composition (2) is applied to the surface of the substrate to form a liquid coating, which is then heated and dried, and then baked to form an F layer. That is, the F layer is a layer containing an F polymer and an aromatic polyimide (PI). The PI in the F layer may be the PI (2) itself contained in the composition (2), or may be a PI in which the imidization reaction has progressed further by heating in the formation of the F layer.
The application method and heating method of the present composition (2) in the production of the laminate, including the preferred embodiments thereof, are the same as those for the present composition (1) described above.
The substrate to which the composition (2) is applied is preferably a metal foil or a heat-resistant resin film.
The definition of such metal foil, including its preferred embodiments and scope, is the same as that of the present composition (1) described above.

The heat-resistant resin film is a film containing one or more types of heat-resistant resin, and may be a single-layer film or a multi-layer film. The heat-resistant resin film may have glass fibers, carbon fibers, or the like embedded therein.
When the substrate is a heat-resistant resin film, it is preferable to form an F layer on both sides of the substrate. In this case, since the F layer is formed on both sides of the heat-resistant resin film, the linear expansion coefficient of the laminate is significantly reduced, and warping is unlikely to occur. Specifically, the absolute value of the linear expansion coefficient of the laminate in this embodiment is preferably 1 to 25 ppm/°C.

Examples of the heat-resistant resin include polyimide, polyarylate, polysulfone, polyarylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystalline polyester, and liquid crystalline polyesteramide, and polyimide (particularly, aromatic polyimide) is preferred.
In this case, the aromatic rings of the PI of the F layer and the aromatic rings of the aromatic polyimide of the heat-resistant resin film (substrate) are stacked, which is believed to improve the adhesion of the F layer to the heat-resistant resin film. In addition, in this case, the F layer and the heat-resistant resin film are not a compatible integrated body, but exist as independent layers, so that the low water absorption of the F polymer complements the high water absorption of the aromatic polyimide, and the laminate exhibits low water absorption (high water barrier properties).

In the laminate which is a heat-resistant resin film having F layers on both sides, the thickness (total thickness) is preferably 25 μm or more, more preferably 50 μm or more. The thickness is preferably 150 μm or less.
In such a configuration, the ratio of the total thickness of the two F layers to the thickness of the heat-resistant resin film is preferably 0.5 or more, more preferably 0.8 or more. The ratio is preferably 5 or less.
In this case, the properties of the heat-resistant resin film (high yield strength, low plastic deformation property) and the properties of the F layer (low water absorbency) are exhibited in a well-balanced manner.

A preferred embodiment of the laminate formed from composition (2) in which the substrate is a heat-resistant resin film is a three-layer film in which the heat-resistant resin film is a polyimide film having a thickness of 20 to 100 μm, and an F layer, a polyimide film, and an F layer are laminated in this order in direct contact with each other. In this embodiment, the thicknesses of the two F layers are the same, and preferably 15 to 50 μm. The ratio of the total thickness of the two F layers to the thickness of the polyimide film is preferably 0.5 to 5. A laminate in this embodiment is most likely to exhibit the effects of the laminate described above.

The outermost surface of the F layer of the laminate may be further surface-treated to further improve its linear expansion and adhesion. Examples of the surface treatment method include the same method as the surface treatment method of the F layer of the polymer layer-coated metal foil formed from the composition (1) described above.

On the outermost surface of the layer F of the laminate formed from the present composition (2), another substrate may be further laminated.
The definitions and lamination methods of other substrates, including their preferred embodiments and ranges, are the same as those of the polymer layer-coated metal foil formed from the present composition (1).

When the composition (2) is impregnated into a woven fabric and heated, an impregnated woven fabric is obtained that is impregnated with the F polymer and PI.
The heating conditions for the present composition (2), including their preferred embodiments and ranges, are the same as those for the present composition (1) described above.
The woven fabric is preferably a heat-resistant woven fabric that can withstand heating, more preferably a glass fiber woven fabric, a carbon fiber woven fabric, an aramid fiber woven fabric or a metal fiber woven fabric, and even more preferably a glass fiber woven fabric or a carbon fiber woven fabric.
In particular, from the viewpoint of improving the electrical insulation of the impregnated woven fabric, it is preferable to use, as the woven fabric, a plain-woven glass fiber woven fabric made of an electrically insulating E-glass yarn as specified in JIS R 3410: 2006. In this case, if the woven fabric is treated with a silane coupling agent, the adhesion with the F polymer is further improved.

A third aspect of the present composition (hereinafter also referred to as composition (3)) includes a powder of an F polymer (F powder), at least one aromatic polymer or a precursor thereof selected from the group consisting of aromatic polyamideimide, aromatic polyimide, and aromatic polyester (hereinafter also referred to as "AR (3)"), a surfactant having a hydroxyl group and an oxyalkylene group, and an aprotic polar liquid dispersion medium, in which the content of the F polymer is equal to or greater than the content of the aromatic polymer or the precursor thereof, the hydroxyl value of the surfactant is 100 mgKOH/g or less, and the content of the oxyalkylene group is 10 mass% or more.
Composition (3) has excellent dispersibility of F powder. The reason for this is not entirely clear, but is thought to be as follows.

When the liquid dispersion medium of the liquid composition containing the low polarity F powder and the aromatic compound AR (3) is an aprotic polar liquid dispersion medium, it is not easy to find a surfactant with a high dispersing effect that promotes the interaction between each component. For example, if a highly hydrophobic surfactant is used, the dispersibility of the F powder itself increases, but it is also considered that the interaction between AR (3) and the liquid dispersion medium decreases. The present inventors have found that when the content of the F polymer in the liquid composition increases, this phenomenon becomes more pronounced, and sedimentation, aggregation, and phase separation of the F powder are more likely to occur.
Furthermore, as a result of intensive research, the present inventors have found that in such a case, the surfactant needs to have a certain degree of hydrophilicity, specifically, that it needs to contain a predetermined amount of hydroxyl groups and AO groups, respectively. In other words, they have found that if the surfactant contains strong hydrophilic hydroxyl groups and mildly hydrophilic AO groups in respective predetermined ranges, the hydrophilicity is balanced, promoting the dispersion and interaction of each component.

It can be said that the extreme change in hydrophilicity of the surfactant in the present composition (3) due to the change in the amount of hydroxyl groups is suppressed by adjusting the AO content, which is considered to balance the affinity of the surfactant to both the F polymer and AR (3), improving the dispersibility of the present composition (3) as a whole.
As a result, in a molded article (such as an F layer (coating film)) formed from this composition (3), it is believed that the high level of interaction between the F polymer and AR (3) results in the high level of physical properties of each polymer. For example, since the molded article contains AR (3), it has a low linear expansion coefficient, and therefore is less prone to warping and has excellent adhesion and bonding properties. In addition, the aromatic ring in AR (3) has good UV absorption properties, and therefore it is also excellent in processability with a UV-YAG laser or the like. And, since the molded article contains an F polymer, the physical properties of the F polymer (particularly electrical properties such as low dielectric constant and low dielectric tangent) are remarkably excellent.
The above-mentioned effects are more pronounced in the preferred embodiments of the present invention described below.

The definitions of the F polymer and the F powder in the present composition (3), including preferred embodiments, are the same as those in the present composition (1) or (2). The F polymer in the present composition (3) is preferably a PFA containing TFE units and PAVE units and having a melting temperature of 260 to 320°C.
AR (3) in this composition (3) is a material other than an F polymer, and is at least one polymer having an aromatic ring in the main chain selected from the group consisting of aromatic polyamideimide, aromatic polyimide, and aromatic polyester, or a prepolymer forming the above polymer.
AR(3) is more preferably an aromatic polyimide or a precursor thereof, or a liquid crystalline aromatic polyester, and further preferably an aromatic polyimide or a precursor thereof.

The embodiment of the aromatic polyimide is the same as that of PI (2) in the present composition (2) described above.
An example of the aromatic polyester is a liquid crystal polyester. Examples of the liquid crystal polyester include the polymers described in paragraphs [0010] to [0015] of JP-A-2000-248056. Specific examples of aromatic polyesters include polymers of dicarboxylic acids (terephthalic acid, isophthalic acid, diphenyl ether-4,4'-dicarboxylic acid, acetic anhydride, etc.), dihydroxy compounds (4,4'-biphenol, etc.), aromatic hydroxycarboxylic acids (4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, etc.), aromatic diamines, aromatic hydroxyamines, aromatic aminocarboxylic acids, etc. More specific examples of aromatic polyesters include a reaction product of 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, a reaction product of 6-hydroxy-2-naphthoic acid, terephthalic acid, and acetaminophen, and a reaction product of 4-hydroxybenzoic acid, terephthalic acid, and 4,4'-biphenol.

The form of the aprotic polar liquid dispersion medium in composition (3) is the same as that in composition (2) described above.

The surfactant in the present composition (3) has a hydroxyl value of 100 mgKOH/g or less and an oxyalkylene group content of 10 mass % or more.
The hydroxyl value of the surfactant is preferably 100 mgKOH/g or less, more preferably 75 mgKOH/g or less, and even more preferably 50 mgKOH/g or less. The lower limit of the hydroxyl value is preferably 10 mgKOH/g or more.
The content of the oxyalkylene group in the surfactant is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The upper limit of the content of the oxyalkylene group is preferably 50% by mass or less.
The embodiments of the hydroxyl group and oxyalkylene group as the hydrophilic portion of the surfactant, including the preferred ranges thereof, are the same as those of the surfactant in the present composition (1).
Furthermore, the surfactant preferably has a perfluoroalkyl group or a perfluoroalkenyl group as the hydrophobic portion.

The surfactant in composition (3) is preferably a copolymer of a compound represented by the following formula (F) and a compound represented by the following formula (H). The amount of units based on the compound represented by formula (F) relative to all units contained in the copolymer is preferably 60 to 90 mol %, more preferably 70 to 90 mol %.
The amount of units based on the compound represented by formula (H) relative to all units contained in the copolymer is preferably from 10 to 40 mol %, more preferably from 10 to 30 mol %.
The total amount of the units based on the compound represented by formula (F) and the compound represented by formula (H) relative to all units contained in the copolymer is preferably 90 to 100 mol %, more preferably 100 mol %.
_CH2 =CHR ^F -C(O)O-Q ^F -X ^F ... (F)
CH ₂ ═CHR ^H —C(O)O—(Q ^H ) _m —OH...(H)
R 3 ^F represents a hydrogen atom or a methyl group.
Q ^{1 F} represents an alkylene group having 1 to 4 carbon atoms or an oxyalkylene group having 1 to 4 carbon atoms.
^XF represents a perfluoroalkyl group having 4 to 6 carbon atoms or a perfluoroalkenyl group having 4 to 12 carbon atoms.
R ^H represents a hydrogen atom or a methyl group.
^QH represents an oxyalkylene group having 2 to 4 carbon atoms.
m represents an integer from 1 to 120.

The definitions of the viscosity, thixotropy ratio, and water content of the present composition (3), including preferred embodiments thereof, are the same as those of the present composition (1) or (2).
The composition (3) may contain a polymer other than the F polymer and AR (3), an inorganic filler, a thixotropy imparting agent, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a brightening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, a viscosity adjusting agent, and a flame retardant.
The preferred embodiments and ranges of the inorganic filler in the present composition (3) are the same as those of the inorganic filler in the present composition (2).

The content (ratio) of the F polymer in the composition (3) is preferably equal to or greater than the content (ratio) of AR (3). In this case, not only can the properties based on the F polymer and the properties based on AR (3) be imparted to the obtained molded article in a good balance, but also the physical properties of the F polymer are easily expressed to a high degree.
Specifically, the content of the F polymer in the composition (3) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass. The content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. In this case, it is easy to form a molded product having excellent electrical properties and adhesion to a substrate.

The content of AR (3) in the composition (3) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more. The content is preferably 50% by mass or less, more preferably 25% by mass or less, and even more preferably 10% by mass or less. In this case, it is easy to form a molded product with improved UV processability.
The mass ratio of the content (proportion) of AR (3) to the content (proportion) of the F polymer in the composition (3) is preferably 1 or less, more preferably 0.5 or less, and further preferably 0.1 or less.
The content (proportion) of the aprotic polar liquid dispersion medium in the composition (3) is preferably from 40 to 90 mass %, more preferably from 50 to 80 mass %.
The content (ratio) of the surfactant in the composition (3) is preferably 1 to 15% by mass, in which case the inherent physical properties of the F polymer in the molded article are more likely to be improved.

This composition (3) is applied to the surface of a substrate and heated to form a polymer layer (F layer) containing an F polymer and an aromatic polymer (AR), thereby obtaining a laminate having the substrate and the F layer in this order.
Furthermore, when the composition (3) is impregnated into a woven fabric and heated, an impregnated woven fabric impregnated with the F polymer and the aromatic polymer (AR) can be obtained.
The AR in the F layer or the impregnated woven fabric may be the AR (3) itself contained in the composition (3), or may be an AR in which a structural transformation (e.g., an imidization reaction) has progressed due to heating in the formation of the F layer or the impregnated woven fabric.
The laminate or impregnated woven fabric formed from the present composition (3) and the manufacturing method thereof are similar to those of the present composition (2), including the preferred embodiments thereof.

A fourth aspect of the present composition (hereinafter also referred to as the present composition (4)) includes an aspect that includes an F polymer powder (F powder), an aromatic polyimide or a precursor thereof (hereinafter also referred to as "PI (4)"), and a non-aqueous liquid dispersion medium (non-aqueous liquid medium), in which the F polymer content is 10 mass% or more and the water content (moisture content) is 1000 to 50000 ppm.
By using the composition (4), it is easy to form a relatively thin F layer that contains F polymer and aromatic polyimide densely (at high density), has a high content of F polymer, and suppresses defects such as holes. The reason for this is not necessarily clear, but is thought to be as follows.

In the process of forming the F layer from the composition (4), it is believed that the packing and melting/sintering of the F powder and the reaction of PI (4) proceed in parallel due to heating. Here, the reaction of PI (4) refers to a reaction between the terminal groups of PI (4) (such as an imidization reaction between an amino group contained in the terminal group and an acid anhydride group or a carboxyl group contained in the terminal group) or a ring-closing reaction of an amic acid unit in a polyimide or its precursor, which is a reaction accompanied by dehydration. The amount of water (amount of evaporated water) generated by the reaction of PI (4) depends on the amount of reactant and the heating temperature, and is particularly large at the beginning of heating, and varies greatly during the above process. In particular, it is believed that the rapid evaporation of water at the beginning of heating inhibits the packing of the F powder and increases the defects of the F layer.

Therefore, in the present composition (4), a certain amount of water is intentionally included. In other words, by including a certain amount of water, the progress of the reaction of PI (4) at the beginning of heating is suppressed, and as the water evaporates due to heating, the reaction of PI (4) gradually increases, thereby balancing the amount of water evaporated during the heating process. It is believed that this prevents defects from occurring in the F layer that is formed. In addition, the heat generation and volume change associated with the reaction of PI (4) are also balanced during the heating process, and an F layer with high shape stability is formed, so that defects in the F layer are suppressed.
Furthermore, since the composition (4) contains a specified amount of water, deterioration due to reaction of PI (4) during storage can be suppressed, and it is considered that the composition (4) also has excellent dispersion stability.

Specifically, even if the composition (4) contains a relatively large amount of PI (4), the viscosity or thixotropy is maintained, and the sedimentation, aggregation, and phase separation of each component can be suppressed. As a result, it is considered that the physical properties of the F polymer and polyimide are highly expressed in the F layer (molded product) formed from the composition (4). For example, since the F layer contains an aromatic polyimide, it has a low linear expansion coefficient, and therefore is less likely to warp, which is advantageous for thickening. In addition, due to the good UV absorption of the aromatic rings of the aromatic polyimide, it is also excellent in processability with a UV-YAG laser or the like. Furthermore, the F layer highly expresses the physical properties of the F polymer (particularly electrical properties such as low dielectric constant and low dielectric tangent).
The above-mentioned effects are more pronounced in the preferred embodiments of the present composition (4) described below.

The definition of the F polymer in the present composition (4), including its preferred embodiments, is the same as that in the present composition (1). The F polymer in the present composition (4) is preferably a PFA containing a TFE unit and a PAVE unit.
In particular, the melting temperature of the F polymer in the composition (4) is preferably from 280 to 325°C, more preferably from 285 to 320°C.
The glass transition point of the F polymer is preferably from 75 to 125°C, and more preferably from 80 to 100°C.
The definition of F powder in composition (4) is the same as that in composition (2), including preferred embodiments and ranges.

PI(4) is preferably an aromatic polyimide or an aromatic polyamic acid.
Aromatic polyimides are units based on carboxylic dianhydrides and diamines, and have units formed by the imidization reaction of the two compounds (units having an imide structure; hereinafter, also referred to as "imide units"). Incidentally, aromatic polyimides may be composed only of imide units, or may have imide units and units formed by the amidation reaction of the two compounds (units having an amic acid structure; hereinafter, also referred to as "amic acid units"). On the other hand, aromatic polyamic acid is a polymer composed only of amic acid units.

In the PI (4), at least one of the carboxylic dianhydride and the diamine, and at least a part of the diamine, is an aromatic compound. The carboxylic dianhydride and the diamine may each be one compound or a plurality of compounds. It is preferable to use at least one aromatic carboxylic dianhydride as the carboxylic dianhydride.
However, PI (4) is preferably an aromatic polyimide or polyamic acid having an imidization rate of less than 99%. Such PIs have a high concentration of reactive substrates and undergo rapid reaction upon heating, so that the reaction moderation effect of the present composition (4) containing a specified amount of water is more likely to be exhibited significantly.
The definition of the imidization rate of PI (4) in composition (4), the method of controlling it, and the method of measuring it are the same as those in PI (2) described above.

The imidization rate of PI (4) is more preferably 10 to 95%, further preferably 25 to 90%, and particularly preferably 50 to 80%. With a given imidization rate, PI (4) forms an imide group (ring closure) with the imidization reaction, and its polarity (dissociable proton) decreases, so that its solubility (or dispersibility) in the composition (4) tends to decrease, while its affinity with the F polymer tends to increase. For this reason, it is considered that such PI (4) functions as a dispersant to promote the dispersion of the F powder. In addition, the inclusion of such PI (4) maintains the viscosity or thixotropy of the composition (4), making it easier to suppress the precipitation, aggregation, and phase separation of each component.
The imidization rate of the aromatic polyamic acid was 0%.

PI (4) preferably contains a unit based on an aromatic tetracarboxylic acid dianhydride and an aromatic diamine or an aliphatic diamine having a linking structure in which two or more arylene groups are linked via a linking group. Such PI (4) shows a tendency to have a higher affinity with the F polymer, and not only increases the dispersibility of the composition (4), but also tends to improve the adhesiveness of the F layer formed therefrom. In other words, such PI (4) tends to function both as a dispersant in the composition (4) and as an adhesive component in the F layer.
The preferred embodiments of the aromatic tetracarboxylic acid dianhydride, aromatic diamine, and aliphatic diamine in PI (4) are the same as those in the present composition (2) described above.

The non-aqueous liquid dispersion medium in the composition (4) is preferably at least one liquid compound selected from the group consisting of amides, ketones, and esters. The non-aqueous liquid dispersion medium may be used alone or in combination of two or more.
The boiling point of the non-aqueous liquid dispersion medium is preferably 125 to 250° C. In this case, when the liquid coating of the present composition (4) is dried to form a dry coating, the flow of the F powder due to the evaporation of the non-aqueous liquid dispersion medium progresses effectively, and the F powder is likely to be densely packed.
Suitable specific examples of the non-aqueous liquid dispersion medium in the present composition (4) are the same as the aprotic polar liquid dispersion medium in the present composition (2).

The present composition (4) preferably contains a surfactant having a hydroxyl group or an oxyalkylene group as the hydrophilic portion.
The definition of the surfactant in the present composition (4), including preferred embodiments thereof, is the same as that in the present composition (1).

The water content of the composition (4) is 1,000 to 50,000 ppm.
The water content of the composition (4) is preferably more than 5000 ppm, more preferably 7500 ppm or more. The water content of the composition (4) is preferably 30000 ppm or less, more preferably 20000 ppm or less. If the water content of the composition (4) is within the above range, the amount of water evaporated during the heating process is more balanced without impairing the reaction of PI (4) itself, and defects in the formed polymer layer can be further reduced. In addition, the composition (4) is likely to become a liquid composition with excellent dispersion stability and handling properties.
The viscosity of the composition (4) is preferably 10,000 mPa·s or less, and more preferably 10 to 1,000 mPa·s.
The thixotropy ratio of the present composition (4) is preferably 1-2.

The definitions of the viscosity and thixotropy ratio of the present composition (4), including preferred embodiments and ranges, are the same as those of the present composition (2).
The composition (4) may contain a polymer other than the F polymer and PI (4), an inorganic filler, a thixotropic agent, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, a viscosity adjusting agent, and a flame retardant.
The preferred embodiments and ranges of the inorganic filler in the present composition (4) are the same as those of the inorganic filler in the present composition (2).

The content of the F polymer in the composition (4) is preferably equal to or greater than the content of PI (4). In this case, a dense F layer having high physical properties of the F polymer is easily obtained, and the obtained F layer is easily imparted with a good balance of properties based on the F polymer and properties based on PI (4).
Specifically, the content of the F polymer in the composition (4) is 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. The content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. In this case, it is easy to form an F layer having excellent electrical properties and adhesion to a substrate.

The content of PI (4) in the composition (4) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. In this case, it is easy to form an F layer with improved UV processability.
The content of the non-aqueous liquid dispersion medium in the composition (4) is preferably from 40 to 90% by mass, and more preferably from 50 to 80% by mass.
When the composition (4) contains a surfactant, the content thereof is preferably 1 to 15% by mass, in which case the inherent physical properties of the F polymer in the F layer are more likely to be improved.

This composition (4) is applied to the surface of a substrate and heated to form an F layer containing an F polymer and an aromatic polyimide (PI), thereby obtaining a laminate having the substrate and the F layer in this order.
The PI in the F layer may be the PI (4) itself contained in the composition (4), or may be a PI in which the imidization reaction has further progressed due to heating during the formation of the F layer.
The definition of the laminate formed from the present composition (4) is the same as that of the laminate formed from the present composition (2), including preferred embodiments and ranges.

The liquid composition of the present invention and the laminate or impregnated woven fabric obtained from the liquid composition of the present invention have been described above, but the present invention is not limited to the configurations of the above-mentioned embodiments.
For example, the liquid composition of the present invention and the laminate or impregnated woven fabric of the present invention obtained from such a liquid composition may each have any other optional components in addition to the components of the above-mentioned embodiments, or may be replaced with any optional components that produce a similar effect.

The present invention will be explained in detail below with reference to examples, but the present invention is not limited to these.

1. Example of production of liquid composition and its evaluation (part 1)
1-1. Preparation of each ingredient [Powder]
Powder 11: Powder (D50: 1.7 μm) made of F polymer 11 (melting temperature: 300° C.) containing 98.0 mol%, 0.1 mol%, and 1.9 mol% of TFE units, NAH units, and PPVE units, in that order.
Powder 12: Powder (D50: 1.3 μm) made of F polymer 12 (melting temperature: 305° C.) containing 97.5 mol % and 2.5 mol % of TFE units and PPVE units, in that order.
[Solvent (liquid dispersion medium)]
NMP: N-methyl-2-pyrrolidone

[Binder resin]
Binder resin 11: Non-reactive thermoplastic polyimide (manufactured by Mitsubishi Gas Chemical Company, Inc., "Neoplum"; 20% weight loss temperature: 300°C or higher, 5% weight loss temperature: 300°C or higher, glass transition point: 260°C)
Binder resin 12: Non-reactive thermoplastic polyimide ("Spixeria" manufactured by Somar; 20% weight loss temperature: 300°C or higher, 5% weight loss temperature: 300°C or higher)
Binder resin 13: Dehydration condensation reaction type thermosetting polyimide (polyimide precursor containing polyamic acid; 20% weight loss temperature: 300° C. or higher, 5% weight loss temperature: 300° C. or higher)
Binder resin 14: Non-reactive thermoplastic acrylic resin (20% weight loss temperature: less than 260°C)
The binder resins are all soluble in NMP.

[Dispersant (surfactant)]
Dispersant 11: Nonionic (meth)acrylate polymer having a perfluoroalkenyl group, a polyoxyethylene group, and an alcoholic hydroxyl group on the side chain (manufactured by Neos Corporation, "Ftergent 710FL")
[Metal foil]
Copper foil 11: Low-roughening electrolytic copper foil (thickness: 12 μm, ten-point average roughness of surface: 0.08 μm)

1-2. Production of liquid composition NMP (66.7 parts by mass) and dispersant 11 (3 parts by mass) were added to a pot to prepare a solution, and then powder 11 (30 parts by mass) and binder resin 11 (0.3 parts by mass) were added. Zirconia balls were then added, and the pot was rolled at 150 rpm for 1 hour to produce liquid composition 11 in which powder 11 was dispersed.
Liquid composition 11 had a viscosity of 1000 mPa·s or less (25 mPa·s) at 25° C., and even when left to stand at 25° C., no significant sediment was formed, and the liquid composition had excellent dispersibility.
(Liquid Compositions 12 to 15)
Liquid compositions 12 to 15 were produced in the same manner as liquid composition 11, except that the types and amounts of the components were changed as shown in Table 1 below.
The types and amounts of the components of each liquid composition are shown in Table 1. In Table 1, the numbers in parentheses indicate the amounts used (parts by mass), and "binder resin/F polymer" indicates the mass ratio of the binder resin content to the F polymer content in the liquid composition.

1-3. Production of polymer-layered copper foil (polymer-layered copper foil 11)
The liquid composition 11 was applied to the surface of the copper foil 11 by a roll-to-roll method using a small-diameter gravure reverse method to form a liquid coating. The copper foil was then passed through a drying furnace and dried by heating at 100°C, 120°C, and 130°C in that order for a total of 5 minutes. The dried coating was then heated at 340°C for 3 minutes in a far-infrared oven under a nitrogen atmosphere. This produced a polymer-layered copper foil 11 in which an F layer 11 (thickness: 4 μm) was formed on the surface of the copper foil 11.
(Polymer-Layered Copper Foils 12 to 15)
Polymer layer-coated copper foils 12 to 15 were produced in the same manner as polymer layer-coated copper foil 11, except that liquid compositions 12 to 15 were used instead of liquid composition 11, respectively.
The obtained polymer layer-coated copper foil was evaluated as follows.

1-4. Evaluation of polymer-layered copper foil <Adhesion>
The cross section of the polymer layer-attached copper foil was observed by SEM, and the state of the interface between the copper foil and the F layer was evaluated according to the following criteria.
A: The interface is tightly adhered over the entire surface.
B: The interface is in close contact over the entire surface, but there are some areas where voids exist.
C: Voids are present over the entire interface.

<Peel strength>
A rectangular test piece (length 100 mm, width 10 mm) was cut out from the polymer layer-attached copper foil. The test piece was fixed at a position 50 mm from one end in the longitudinal direction, and the copper foil and the F layer were peeled off from one end in the longitudinal direction at an angle of 90° to the test piece at a pulling speed of 50 mm/min. The maximum load at this time was measured as the peel strength (N/cm) and evaluated according to the following criteria.
A: The peel strength is 12 N/cm or more.
B: The peel strength is 8 N/cm or more and less than 12 N/cm.
C: The peel strength is less than 8 N/cm.

<Solder heat resistance>
When the polymer layer-coated copper foil was subjected to a solder heat resistance test in which it was floated in a solder bath at 288° C. for 5 seconds, it was visually confirmed whether the copper foil floated from the F layer, and evaluated according to the following criteria.
A: The above phenomenon does not occur even after repeated testing.
B: The above phenomenon does not occur in one test, but occurs when the test is repeated.
C: The above phenomenon occurs in one test.

<Warpage>
A polyimide film was placed on the surface of the F layer of the polymer-layered copper foil, and laminated by a vacuum hot press method (press temperature: 340° C., press pressure: 4 MPa, press time: 60 minutes), and evaluated according to the following criteria.
A: The polymer layer-coated copper foil and the polyimide film can be laminated without any problems.
B: The polymer layer-coated copper foil curls in part, but can be laminated with the polyimide film without any problems.
C: The polymer layer-attached copper foil curled significantly and could not be laminated with the polyimide film.

The interface between the copper foil 11 and the F layer 11 in the polymer layer-coated copper foil 11 was dense, and no voids were found. Furthermore, the outermost surface of the F layer 11 of the polymer layer-coated copper foil 11 was observed by SEM, and the surface was found to be highly smooth and with no defects. Furthermore, the gloss of the copper foil 11 of the polymer layer-coated copper foil 11 was visually confirmed from the F layer 11 side, and there was no change in gloss from the original copper foil 11 used. Furthermore, a printed circuit board having a transmission circuit formed by etching the copper foil 11 of the polymer layer-coated copper foil 11 was resistant to warping when heated.

The polymer layer-attached copper foil 11 was produced from the dispersion 11 (a dispersion using an F polymer and a binder resin, the glass transition point of the binder resin being lower than the melting temperature of the F polymer). The F layer 11 exhibited good UV absorption properties, and had a dielectric constant and a dielectric dissipation factor (measurement frequency: 10 GHz) of 2.0 and 0.0061, respectively, and thus had excellent electrical properties.
It is to be noted that, from the results in Table 2, it was confirmed that the results of each evaluation varied with the change in the type of F polymer and binder resin.

2. Example of production of liquid composition and evaluation thereof (part 2)
2-1. Preparation of each component [F polymer]
F polymer 21: A polymer containing TFE units, NAH units and PPVE units in the order of 98.0 mol%, 0.1 mol% and 1.9 mol% and having a polar functional group (melting temperature: 300° C., glass transition point: 95° C.)
F polymer 22: A polymer containing 97.5 mol% TFE units and 2.5 mol% PPVE units, in that order, and having no polar functional groups (melting temperature: 305° C., glass transition point: 85° C.)
[powder]
Powder 21: Powder made of F polymer 21 (D50: 1.7 μm)
Powder 22: Powder made of F polymer 22 (D50: 3.2 μm)

[PI or polyamic acid]
PI21: Polyimide containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 (imidization rate: 50% or more)
PI22: Polyimide containing a compound represented by the above formula AN6 and a unit based on an aliphatic diamine (imidization rate: 50% or more)
PI23: Polyimide containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 (imidization rate: 5%)
PA21: Polyamic acid containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 (imidization rate: 0%)

[Aprotic polar liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone [surfactant]
Surfactant 21: Copolymer of methacrylate having a perfluoroalkyl group and methacrylate having a hydroxyl group and an oxymethylene group

The imidization rate of PI or polyamic acid was measured according to the following method.
Using dimethylsulfoxide- _d6 as a solvent, ¹ H-NMR of each PI solution or polyamic acid solution was measured, and the imidization rate was calculated according to the following formula (I) from the ratio of the integral value of the aromatic proton peak to the integral value of the carboxylic acid proton peak.
Imidization rate (%)={1-(Y/Z)×(1/X)}×100 (I)
X: integral value of carboxylic acid proton peak/integral value of aromatic proton peak when imidization rate is 0%, determined from the amount of monomer charged. Y: integral value of carboxylic acid proton peak obtained from ¹ H-NMR measurement. Z: integral value of aromatic proton peak obtained from ¹ H-NMR measurement.

2-2. Preparation of liquid composition (Example 21)
NMP (64 parts by mass) and surfactant 21 (3 parts by mass) were added to a pot to prepare a solution, and then Powder 21 (30 parts by mass) and PI 21 (3 parts by mass) were added. Zirconia balls were then added, and the pot was rolled at 150 rpm for 1 hour to produce liquid composition 21 in which Powder 21 was dispersed.
(Example 22)
NMP and surfactant 21 were added to a pot to prepare a solution, and then powder 21 was added and the pot was rolled at 150 rpm for 1 hour to prepare a dispersion liquid in which powder 21 was dispersed. This dispersion liquid was mixed with a varnish of PI22 to produce a liquid composition 22 in which powder 21 was dispersed, containing 30 mass% each of powder 21 and PI22.
(Example 23)
Liquid composition 23 was obtained in the same manner as liquid composition 21, except that PI23 was used instead of PI21.

(Example 24)
Liquid composition 24 was obtained in the same manner as liquid composition 21, except that powder 22 was used instead of powder 21.
(Example 25)
Liquid composition 25 was obtained in the same manner as liquid composition 24, except that PA21 was used instead of PI21.

After long-term storage of each liquid composition, the dispersion state was visually confirmed, and the dispersibility was evaluated according to the following criteria.
A: It was uniformly redispersed with only light stirring.
B: When stirred with shear, it was uniformly redispersed.
C: When stirred with shear, the particles were uniformly redispersed, but were disproportionated.
The results are summarized in Table 3 below.

2-3. Manufacturing of Laminate An aromatic polyimide film (manufactured by SKC Kolon PI, product number "FS-200") having a thickness of 50 μm was prepared. Liquid composition 21 was applied to one side of this film by a small diameter gravure reverse method, and the film was passed through a ventilation drying oven (oven temperature: 150° C.) for 3 minutes to remove NMP and form a dry film. Furthermore, liquid composition 21 was similarly applied to the other side of the film and dried to form a dry film.
Next, the film with the dry coating formed on both sides was passed through a far-infrared oven (oven temperature: 380°C) for 20 minutes to melt and bake the powder (F polymer). This resulted in an aromatic polyimide film with F layers (thickness: 25 μm) containing F polymer 21 and PI 21 formed on both sides, i.e., laminate 21. The absolute value of the linear expansion coefficient of laminate 21 was 25 ppm/°C or less, and it had adhesiveness and electrical properties (low dielectric constant and low dielectric loss tangent).

Copper foil 21 (low-roughening electrolytic copper foil having a thickness of 12 μm and a surface ten-point average roughness of 0.08 μm) was placed on both sides of the laminate 21, and pressed under vacuum at 340° C. for 20 minutes to obtain a double-sided copper-clad laminate 21. Each layer of the double-sided copper-clad laminate 21 was firmly bonded, and even when subjected to a solder reflow test in which the laminate was floated in a solder bath at 288° C. for 60 seconds 10 times, no blistering or peeling occurred at the interface of the layers.
When the double-sided copper-clad laminate 21 was irradiated with a UV-YAG laser (laser output: 1.5 W, laser focal diameter: 25 μm, number of revolutions on the circumference: 16, oscillation frequency: 40 kHz), a good circular through hole could be formed.
When Liquid Composition 22 was used instead of Liquid Composition 21, a similar double-sided copper-clad laminate was obtained.

Furthermore, when the liquid composition 22 was applied to the surface of the copper foil 21 and heated, a laminate having the copper foil 21 and the F layer in this order was obtained. In this laminate, the polymer layer was firmly adhered to the surface of the copper foil 21, the occurrence of warping was suppressed, and the laminate had high adhesion and excellent electrical properties (low dielectric constant and low dielectric tangent).

3. Example of production of liquid composition and evaluation thereof (part 3)
3-1. Preparation of each component [F polymer]
F polymer 31: A polymer containing 98.0 mol%, 0.1 mol%, and 1.9 mol% of TFE units, NAH units, and PPVE units, in that order, and having a polar functional group (melting temperature: 300° C., glass transition point: 95° C.)
F polymer 32: A polymer containing 97.5 mol% TFE units and 2.5 mol% PPVE units, in that order, and having no polar functional groups (melting temperature: 305° C., glass transition point: 85° C.)
[powder]
Powder 31: Powder made of F polymer 31 (D50: 1.7 μm)
Powder 32: Powder made of F polymer 32 (D50: 3.2 μm)

[ARs]
PI31: Polyimide containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 (imidization rate: 50% or more)
PI32: Polyimide containing a unit based on the compound represented by the above formula AN6 and an aliphatic diamine (imidization rate: 50% or more)
PA31: Polyamic acid containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 (imidization rate: 0%)
PES31: Aromatic polyester (liquid crystal polyester) obtained by reacting 2-hydroxy-6-naphthoic acid (HNA), 4-hydroxyacetanilide (APAP), isophthalic acid (IPA), diphenyl ether-4,4'-dicarboxylic acid (DEDA) and acetic anhydride.

[Aprotic polar liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone [inorganic filler]
Filler 31: Silica filler having an average particle size of 0.5 μm that has been surface-treated with an aminosilane coupling agent (manufactured by Admatechs Co., Ltd., product name "Admafine SO-C2")

[Surfactant]
Three types of surfactants _are copolymers of _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _CF2 ) _6F and at least one compound represented by the formula _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) _xOH (wherein x is 1, 10 or 23), and have the fluorine content, hydroxyl value and _oxyethylene group content shown in Table 4 below.

The imidization rate of PI or polyamic acid was measured in the same manner as in 2-1.

In addition, PES31 was prepared by the following method.
In a reactor under a nitrogen gas atmosphere, HNA, APAP, IPA, DEDA and acetic anhydride (1.1 mol) were charged in the following order: 21 mol%, 13 mol%, 2 mol%, 11 mol%, 52 mol%, and refluxed under stirring (150 ° C, 3 hours). Furthermore, the reaction was continued at 320 ° C while distilling off low boiling components (by-product acetic acid, unreacted acetic anhydride, etc.) (temperature rise time: 170 minutes). The reaction was terminated when the torque in the reactor increased, and the contents were removed, cooled and pulverized. The pulverized product was further held at 240 ° C for 3 hours under a nitrogen gas atmosphere and subjected to a solid-phase reaction to obtain PES31.

3-2. Production of liquid composition (Example 31)
NMP (64 parts by mass) and surfactant 31 (3 parts by mass) were added to a pot to prepare a solution, and then Powder 31 (30 parts by mass) and PI 31 (3 parts by mass) were added. Zirconia balls were then added, and the pot was rolled at 150 rpm for 1 hour to produce liquid composition 31 in which Powder 31 was dispersed.
(Example 32)
NMP and surfactant 31 were added to a pot to prepare a solution, and then powder 31 was added and the pot was rolled at 150 rpm for 1 hour to prepare a dispersion liquid in which powder 31 was dispersed. This dispersion liquid, a varnish of PI 32, and filler 31 were mixed to produce liquid composition 2 in which powder 31 was dispersed, containing 30% by mass, 30% by mass, and 1% by mass of powder 31, PI 32, and filler 31, in that order.

(Example 33)
NMP and surfactant 31 were added to a pot to prepare a solution, and then powder 31 was added and the pot was rolled at 150 rpm for 1 hour to prepare a dispersion in which powder 31 was dispersed. This dispersion, a varnish of PES31 (an NMP solution containing 10% by mass of PES31), and filler 31 were mixed to produce liquid composition 33 in which powder 31 was dispersed, containing 15% by mass each of powder 31, PES31, and filler 31.
(Example 34)
Liquid composition 34 was obtained in the same manner as liquid composition 31, except that powder 32 was used instead of powder 31.

(Example 35)
Liquid composition 35 was obtained in the same manner as liquid composition 34, except that PA31 was used instead of PI31.
(Example 36)
Liquid composition 36 was obtained in the same manner as liquid composition 34, except that the amount of powder 32 was changed to 30 parts by mass and the amount of PI 31 was changed to 30 parts by mass.
(Example 37)
Liquid composition 37 was obtained in the same manner as liquid composition 36, except that the amount of powder 32 was changed to 20 parts by mass and the amount of PI 31 was changed to 40 parts by mass.

(Example 38)
Liquid composition 38 was obtained in the same manner as liquid composition 35, except that surfactant 32 was used instead of surfactant 31.
(Example 39)
Liquid composition 39 was obtained in the same manner as liquid composition 35, except that surfactant 33 was used instead of surfactant 31.

After long-term storage of each liquid composition, the dispersion state was visually confirmed, and the dispersibility was evaluated according to the following criteria.
A: It was uniformly redispersed with only light stirring.
B: When stirred with shear, it was uniformly redispersed.
C: When stirred with shear, the material was uniformly redispersed, but was disproportionated.
D: When stirred with shear, the mixture was uniformly redispersed, but the viscosity increased and the mixture became non-proportionate.
E: When stirred with shear, the mixture turns into a hard cake and is difficult to redisperse.
The results are summarized in Table 5 below.

3-3. Measurement of peel strength An aromatic polyimide film (manufactured by SKC Kolon PI, product number "FS-200") having a thickness of 50 μm was prepared. The liquid composition 31 was applied to one side of this film by a small diameter gravure reverse method, and the film was passed through a ventilation drying oven (oven temperature: 150° C.) for 3 minutes to remove NMP and form a dry coating. Furthermore, the liquid composition 31 was similarly applied to the other side of the film and dried to form a dry coating.
Next, the film with the dry coating formed on both sides was passed through a far-infrared oven (oven temperature: 380°C) for 20 minutes to melt and bake the powder (F polymer). This resulted in an aromatic polyimide film with F layers (thickness: 25 μm) containing F polymer 31 and PI 31 formed on both sides, i.e., laminate 31. The absolute value of the linear expansion coefficient of laminate 31 was 25 ppm/°C or less, and it had adhesiveness and electrical properties (low dielectric constant and low dielectric loss tangent).

Copper foil 31 (low-roughening electrolytic copper foil having a thickness of 12 μm and a surface ten-point average roughness of 0.08 μm) was placed on both sides of the laminate 31, and pressed under vacuum at 340° C. for 20 minutes to obtain a double-sided copper-clad laminate 31. Each layer of the double-sided copper-clad laminate 31 was firmly bonded, and even when subjected to a solder reflow test in which the laminate was floated in a solder bath at 288° C. for 60 seconds 10 times, no blistering or peeling occurred at the interface of the layers.
When the double-sided copper-clad laminate 31 was irradiated with a UV-YAG laser (laser output: 1.5 W, laser focal diameter: 25 μm, number of revolutions on the circumference: 16, oscillation frequency: 40 kHz), a good circular through hole could be formed.
When Liquid Composition 32 was used instead of Liquid Composition 31, a similar double-sided copper-clad laminate was obtained.

Furthermore, when the liquid composition 32 was applied to the surface of the copper foil 31 and heated, a laminate having the copper foil 31 and the F layer in this order was obtained. In this laminate, the polymer layer was firmly adhered to the surface of the copper foil 31, warping was suppressed, and the laminate had high adhesion and excellent electrical properties (low dielectric constant and low dielectric tangent).

4. Example of production of liquid composition and evaluation thereof (part 4)
4-1. Preparation of each component [F polymer]
F polymer 41: A polymer containing 98.0 mol%, 0.1 mol%, and 1.9 mol% of TFE units, NAH units, and PPVE units, in that order, and having a polar functional group (melting temperature: 300° C., glass transition point: 95° C.)
F Polymer 42: A polymer containing 97.5 mol% TFE units and 2.5 mol% PPVE units, in that order, and having no polar functional groups (melting temperature: 305° C., glass transition point: 85° C.)
[powder]
Powder 41: Powder made of F polymer 1 (D50: 1.7 μm)
Powder 42: Powder made of F polymer 2 (D50: 3.2 μm)

[PIs]
PI41: Polyimide containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 PA41: Polyamic acid containing units based on the compound represented by the above formula AN1 and the compound represented by the above formula DA5 [Non-aqueous liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone [surfactant]
Surfactant 41: Copolymer of _CH2 =C( _CH3 )C(O) _{OCH2CH2 ( CF2} ) _6F and _CH2 =C( _CH3 )C( _O )( _OCH2CH2 ) _23OH

4-2. Preparation of liquid composition (Example 41)
NMP and surfactant 41 were added to a pot to prepare a solution, and then powder 41 and a varnish of PI 41 (solvent: NMP) were added. Zirconia balls were then added, and the pot was rolled at 150 rpm for 1 hour to produce a liquid composition 41 containing 57 parts by mass of NMP, surfactant 41, powder 41, and PI 41 in that order, 3 parts by mass, 25 parts by mass, and 15 parts by mass of PI 41, with powder 41 dispersed therein. The water content in the liquid composition 41 was adjusted to 8000 ppm.
(Example 42)
Liquid composition 42 was obtained in the same manner as in Example 41, except that Powder 41 was changed to Powder 42. The water content in Liquid composition 42 was adjusted to 8000 ppm.

(Example 43)
A liquid composition 43 containing 60 parts by mass, 25 parts by mass, and 15 parts by mass of NMP, powder 42, and PI 41, in that order, and having powder 42 dispersed therein, was produced in the same manner as in Example 42, except that surfactant 41 was not used. The water content in liquid composition 43 was adjusted to 8000 ppm.
(Example 44)
Liquid composition 44 was obtained in the same manner as in Example 42, except that the water content was adjusted to 60,000 ppm.

(Example 45)
Liquid composition 45 was obtained in the same manner as in Example 42, except that the water content was adjusted to 800 ppm.
(Example 46)
Except for changing PI 41 to PA 41, the same procedure as in Example 41 was followed to obtain Liquid Composition 46. The water content in Liquid Composition 46 was 20,000 ppm.

4-3. Evaluation of Liquid Compositions After storing each liquid composition for a long period of time, the dispersion state was visually confirmed, and the dispersibility was evaluated according to the following criteria.
A: It was uniformly redispersed with only light stirring.
B: When stirred with shear, it was uniformly redispersed.
C: When stirred with shear, the particles were uniformly redispersed, but were disproportionated.
The results are summarized in Table 6 below.

4-4. Manufacturing of Laminate An aromatic polyimide film (manufactured by SKC Kolon PI, product number "FS-200") having a thickness of 50 μm was prepared. Each liquid composition was applied to one side of this film by a small diameter gravure reverse method, and the film was passed through a ventilation drying oven (oven temperature: 150° C.) for 3 minutes to remove NMP and form a dry film. Furthermore, each liquid composition was similarly applied to the other side of the film and dried to form a dry film.
Next, the film with the dry coating formed on both sides was passed through a far-infrared oven (oven temperature: 380° C.) for 20 minutes to melt and bake the powder (F polymer). As a result, an aromatic polyimide film with a polymer layer (thickness: 8 μm) formed on both sides, i.e., a laminate 41, was obtained.

4-5. Evaluation of Laminates The number of holes present in an area of 10 cm x 10 cm on the surface of the polymer layer of each laminate was visually counted, and the degree of defects was evaluated according to the following criteria.
A: The number of holes was less than 10.
B: The number of holes was 10 or more and less than 25.
C: The number of holes was 25 or more.
The results are summarized in Table 7 below.

The liquid composition of the present invention has excellent dispersibility and can form molded products that have excellent properties (electrical properties, UV processability, low water absorption, etc.) based on tetrafluoroethylene polymers and polymers having an amide structure, an imide structure or an ester structure and an aromatic ring structure in the main chain. The liquid composition of the present invention is suitable as a printed circuit board material.

Claims (6)

A liquid composition comprising a powder of a tetrafluoroethylene-based polymer, a binder resin, and a liquid dispersion medium, wherein the binder resin is an aromatic polyamideimide or aromatic polyimide that is soluble in the liquid dispersion medium and has a 20% weight loss temperature of 260°C or higher, and the mass ratio of the content of the binder resin to the content of the tetrafluoroethylene-based polymer is 0.001 or more and 0.05 or less. The liquid composition according to claim 1, wherein the tetrafluoroethylene-based polymer is a heat-fusible tetrafluoroethylene-based polymer, and the glass transition point of the binder resin is equal to or lower than the melting temperature of the tetrafluoroethylene-based polymer. The liquid composition according to claim 1 or 2, wherein the content of the tetrafluoroethylene-based polymer is 10 to 50 mass %. The liquid composition according to any one of claims 1 to 3, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) and having a melting temperature of 260 to 320°C. The liquid composition according to any one of claims 1 to 4, wherein the aromatic polyimide contains units based on an acid dianhydride of an aromatic tetracarboxylic acid and an aromatic diamine or an aliphatic diamine having a structure in which two or more arylene groups are linked via a linking group. The liquid composition according to any one of claims 1 to 5, further comprising a surfactant having a hydroxyl group and an oxyalkylene group.