JP2022108306A - Composition, production method of polyimide film, and production method of composite film using polyimide film - Google Patents

Abstract

To provide a composition useful for production of a polyimide film in which a tetrafluoroethylene-based polymer is well dispersed, to provide a production method of the polyimide film using the composition, and to provide a production method of a composite film having a substrate layer composed of the polyimide film and a layer composed of the tetrafluoroethylene-based polymer.SOLUTION: A composition comprises 10 mass% or more of an aromatic polyimide or its precursor and 10 mass% or more of particles of a heat meltable tetrafluoroethylene-based polymer respectively, in which melt temperature of the aromatic polyimide is in a range of melt temperature of the heat meltable tetrafluoroethylene-based polymer ±50°C, and the composition is used by mixing with a varnish of the polyimide or its precursor.SELECTED DRAWING: None

Description

The present invention relates to a composition containing particles of a tetrafluoroethylene-based polymer and a predetermined aromatic polyimide, a method for producing a polyimide film using such a composition, and a method for producing a composite film using such a polyimide film.

Tetrafluoroethylene polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as electrical properties, water and oil repellency, chemical resistance, and heat resistance, and are used in various industrial applications such as printed circuit boards. there is A liquid composition containing particles of a tetrafluoroethylene-based polymer is known as a coating agent used for imparting the physical properties to the substrate surface.
Such a liquid composition is attracting attention as a material excellent in electrical properties such as a low dielectric constant and a low dielectric loss tangent for forming a dielectric layer of a printed circuit board corresponding to frequencies in a high frequency band.

Mixing a tetrafluoroethylene polymer and an aromatic resin has also been studied in order to form a more excellent dielectric layer. is disclosed as a polyimide-PTFE blend film made by subjecting the to an imidization process. In Patent Document 2, a polyamic acid varnish is produced, a part of it is taken out, mixed with PTFE particles, mixed with the remaining varnish, and subjected to a heat casting method to produce polyimide-PTFE. A blend film is disclosed.

JP 2005-142572 A WO2016/159061

A tetrafluoroethylene-based polymer has a low surface tension, does not easily interact with other components, and has extremely low dispersion stability. Therefore, in the embodiments described in the prior art documents, the resulting mixture (composition) has low dispersion stability and tends to deteriorate, so that the uniformity and denseness of the component distribution of the molded product obtained therefrom tend to decrease. Furthermore, the present inventors have found that when such a mixture (composition) is cast to obtain a molded product such as a polyimide film, the tetrafluoroethylene-based polymer is difficult to uniformly disperse, and the polyimide and the tetrafluoroethylene-based polymer is likely to undergo phase separation, and as a result, it is difficult for the physical properties of the tetrafluoroethylene-based polymer and the polyimide to be exhibited sufficiently in molded articles.

As a result of intensive studies, the present inventors have found that an aromatic polyimide (or its precursor) having a melting temperature relationship between predetermined tetrafluoroethylene-based polymer particles and the tetrafluoroethylene-based polymer falls within a specific range. A composition containing polyimide is prepared in advance, mixed with a varnish containing polyimide, and molded to obtain a molded product such as a polyimide film in which the tetrafluoroethylene-based polymer is well dispersed and which has excellent uniformity in component distribution and is dense. I found out that In addition, the inventors have found that such a polyimide film has excellent adhesiveness to a tetrafluoroethylene-based polymer, so that a composite film having particularly excellent low dielectric loss tangent, low coefficient of linear expansion, and the like can be obtained from such a polyimide film.
An object of the present invention is to provide a composition useful for producing polyimide films and the like in which a tetrafluoroethylene-based polymer is well dispersed, a method for producing a polyimide film using such a composition, and a base layer made of such a polyimide film and tetrafluoro A method for producing a composite film having a layer comprising an ethylene-based polymer is provided.

The present invention has the following aspects.
<1> A composition containing an aromatic polyimide or a precursor thereof and particles of a heat-melting tetrafluoroethylene-based polymer each in an amount of 10% by mass or more, wherein the melting temperature of the aromatic polyimide is the same as the heat melting A composition which has a melting temperature of a tetrafluoroethylene-based polymer within a range of ±50° C. and is used by mixing with a polyimide or its precursor varnish.
<2> The composition according to <1>, wherein the hot-melt tetrafluoroethylene-based polymer has a melting temperature of 200 to 320°C.
<3> The composition of <1> or <2>, wherein the heat-meltable tetrafluoroethylene-based polymer particles have an average particle diameter (volume-based cumulative 50% diameter) of 0.1 to 25 μm.
<4><1> to <3>, wherein the ratio of the mass of the heat-meltable tetrafluoroethylene-based polymer particles to the mass of the aromatic polyimide or its precursor is in the range of 0.5 to 4. any composition of
<5> The composition according to any one of <1> to <4>, wherein the melting temperature of the aromatic polyimide is equal to or lower than the melting temperature of the polyimide constituting the varnish.
<6> The composition according to any one of <1> to <5>, wherein the melting temperature of the aromatic polyimide is 100° C. or more higher than the boiling point of the solvent contained in the varnish.
<7> The composition according to any one of <1> to <6>, wherein the aromatic polyimide or precursor is an aromatic polyimide precursor.
<8> The composition according to any one of <1> to <7>, wherein the hot-melt tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a carbonyl group-containing group containing a unit based on perfluoro(alkyl vinyl ether). thing.
<9> A method for producing a polyimide film, comprising mixing the composition according to any one of <1> to <8> with a polyimide or a varnish of a precursor thereof and molding the polyimide film by a casting method.
<10> Forming a tetrafluoroethylene-based polymer layer on at least one surface of the polyimide film obtained by the method of <9>, and forming a tetrafluoroethylene-based polymer layer on at least one surface of the polyimide film. A method for manufacturing a composite film comprising:
<11> The method of <10>, wherein the tetrafluoroethylene-based polymer layer is formed by laminating a tetrafluoroethylene-based polymer film on at least one surface of the polyimide film.
<12> The method of <10>, wherein the tetrafluoroethylene-based polymer layer is formed by applying a dispersion containing tetrafluoroethylene-based polymer particles to at least one surface of the polyimide film, followed by heating.
<13> The method of <12>, wherein the dispersion contains an aromatic polyimide, an aromatic polyamideimide, or a precursor thereof.
<14> A composite film obtained by the method according to any one of <10> to <13>.
<15> A printed wiring board comprising the composite film obtained by any one of <10> to <13>.

According to the present invention, a composition useful for producing a polyimide film or the like in which a tetrafluoroethylene-based polymer is well dispersed, a method for producing a polyimide film using such a composition, and a base layer made of such a polyimide film and tetrafluoro A method of making a composite film having a layer comprising an ethylene-based polymer is provided. The polyimide film and the composite film are excellent in physical properties such as electrical properties, and are useful, for example, as constituent materials for printed wiring boards.

The following terms have the following meanings.
"Average particle diameter (D50)" is the volume-based cumulative 50% diameter of the object (particles and filler) determined by a laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, and the cumulative curve is obtained with the total volume of the group of particles being 100%.
"D90" is the volume-based cumulative 90% diameter of the object measured in the same manner.
D50 and D90 of the object are analyzed by a laser diffraction/scattering method using a laser diffraction/scattering particle size distribution analyzer (LA-920 measuring instrument manufactured by Horiba, Ltd.) after dispersing the object in water. Desired.
"Melting temperature" is the temperature corresponding to the maximum melting peak of the polymer as measured by differential scanning calorimetry (DSC).
The “viscosity of the dispersion” is the viscosity measured using a Brookfield viscometer at 25° C. and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average value of the 3 measurements is taken.
The “thixotropic ratio” is a value calculated by dividing the viscosity η ₁ of the dispersion measured at a rotation speed of 30 rpm by the viscosity η ₂ measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average value of the three measurements is taken.
A "unit" in a polymer means an atomic group based on the monomer formed by polymerization of the monomer. The units may be units directly formed by a polymerization reaction, or may be units in which some of said units have been converted to another structure by treatment of the polymer. Hereinafter, units based on monomer a are also simply referred to as "monomer a units".

The composition of the present invention (hereinafter also referred to as "this composition") comprises an aromatic polyimide or its precursor (hereinafter also referred to as "first polyimide") and a heat-melting tetrafluoroethylene polymer. (hereinafter also referred to as “F polymer”.) Particles (hereinafter also referred to as “F particles”) are each contained in an amount of 10% by mass or more, and the melting temperature of the aromatic polyimide (hereinafter referred to as “second 1) is in the range of the melting temperature of the F polymer ± 50 ° C., and is mixed with the varnish of polyimide or its precursor (hereinafter also referred to as "second polyimide"). A composition for use in

The present composition and the mixture obtained by mixing the present composition and the second polyimide varnish are excellent in dispersion stability. In addition, from such a mixture, a molded product such as a polyimide film, in which the F polymer is well dispersed, excellent in uniformity of component distribution, and dense, can be obtained. Such a molded article satisfactorily exhibits physical properties based on polyimide and physical properties based on F polymer, and is excellent in adhesion to other substrates, low water absorption, low linear expansion, electrical properties, and the like. The reason and action mechanism thereof are not necessarily clear, but are presumed as follows, for example.
Particles of tetrafluoroethylene-based polymer tend to form complex secondary particles and agglomerate when mixed with polyimide. However, compared to non-heat-melting tetrafluoroethylene-based polymers, the F polymer easily undergoes molecular motion and has a high degree of conformational freedom, so it easily interacts with polyimide and has a high affinity. Therefore, even when the composition contains a large amount of F particles and the first polyimide, the composition tends to have excellent dispersion stability.
The composition is further used in admixture with a second polyimide varnish. Since the F particles are mixed with the second polyimide in a well-dispersed state, the dispersed state of the F particles is further improved, and the mixture is considered to have excellent dispersion stability. As a result, it is believed that molded articles such as polyimide films having excellent uniformity of component distribution can be obtained from the present composition.
In addition, since the melting temperature of the first polyimide is within the range of the melting temperature of the F polymer ± 50 ° C., when the mixture of the present composition and the second polyimide varnish is heat-molded, the F polymer and the first polyimide of polyimide proceeds in parallel. As a result, the F polymer and the first polyimide are in close contact with each other, and it is believed that a molded product such as a dense polyimide film can be obtained.

In the present composition, D50 of F particles is preferably 0.1 to 25 μm. D50 of the F particles is preferably 20 μm or less, more preferably 10 μm or less. D50 of the F particles is preferably 0.01 μm or more, more preferably 0.1 μm or more. Moreover, D90 of the F particles is preferably 10 μm or less. In this range of D50 and D90, the F particles tend to have good fluidity and dispersibility.

In the present composition, the bulk density of the F particles is preferably 0.15 g/m ² or more, more preferably 0.20 g/m ² or more, from the viewpoint of dispersion stability. The bulk density of F particles is preferably 0.50 g/m ² or less, more preferably 0.35 g/m ² or less.

The F particles may contain a resin or an inorganic filler other than the F polymer, but preferably contain the F polymer as a main component. The content of the F polymer in the F particles is preferably 80% by mass or more, more preferably 100% by mass.
Examples of the resin include heat-resistant resins such as aromatic polyesters, polyamideimides, thermoplastic polyimides, polyphenylene ethers, and polyphenylene oxides.
Examples of inorganic fillers include silicon oxide (silica), metal oxides (beryllium oxide, cerium oxide, alumina, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride, and magnesium metasilicate (steatite). . At least part of the surface of the inorganic filler may be surface-treated.

The F particle containing a resin other than the F polymer or an inorganic filler has a core-shell structure in which the F polymer is the core and the shell is the resin other than the F polymer or the inorganic filler, or the F polymer is the shell and the other than the F polymer. It may have a core-shell structure with a resin or inorganic filler in the core. Such F particles are obtained, for example, by coalescing (collision, aggregation, etc.) particles of F polymer and particles of resin or inorganic filler other than F polymer.

The F polymer in the present composition is a hot melt polymer containing units based on tetrafluoroethylene (TFE) (TFE units). The melting temperature of the F polymer is preferably from 200 to 320°C, more preferably from 260°C to less than 320°C, still more preferably from 280°C to less than 320°C, and more preferably from 290°C to less than 310°C. In such a case, the heat resistance of the polyimide film formed using the present composition tends to be excellent.
The glass transition point of F polymer is preferably 75 to 125°C, more preferably 80 to 100°C.

As F polymers, polymers containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units) (PFA), polymers containing TFE units and units based on ethylene (ETFE), TFE units and hexafluoropropene Polymers (FEP) containing units based on (HFP) are mentioned, preferably PFA. PAVE is preferably CF ₂ =CFOCF ₃ , CF ₂ =CFOCF ₂ CF ₃ and CF ₂ =CFOCF ₂ CF ₂ CF ₃ (PPVE), more preferably PPVE. Each of ETFE, PFA and FEP may further contain other units.
The F polymer is preferably PFA or FEP, more preferably PFA.

The F polymer preferably has polar functional groups. In this case, the F polymer and the first polyimide tend to interact with each other, and the present composition tends to have excellent dispersion stability. Moreover, when a polyimide film is obtained using this composition, the F polymer and the first polyimide form crosslinks during heating, which is preferable in that a dense polyimide film can be obtained.
The polar functional group may be contained in a unit in the F polymer or may be contained in the terminal group of the main chain of the polymer. The latter embodiment includes an F polymer having a polar functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and an F polymer having a polar functional group obtained by plasma treatment or ionizing radiation treatment of the F polymer. mentioned. The polar functional group is preferably a hydroxyl group-containing group, a carbonyl group-containing group and a phosphono group-containing group, and more preferably a hydroxyl group-containing group and a carbonyl group-containing group from the viewpoint of adhesion of the polyimide film formed using the present composition. , a carbonyl group-containing group is more preferred.
The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH, -C(CF ₃ ) ₂ OH and 1,2-glycol group (-CH(OH)CH ₂ OH). .
A carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and includes a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH ₂ ), an acid anhydride residue, Groups (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.) and carbonate groups (-OC(O)O-) are preferred, and acid anhydride residues is more preferred.
When the F polymer has a carbonyl group-containing group, the number of carbonyl group-containing groups in the F polymer is preferably 10 to 5000, more preferably 100 to 3000, more preferably 800 per 1 × 10 ⁶ carbon atoms in the main chain. ~1500 is more preferred. The number of carbonyl group-containing groups in the F polymer can be quantified by the method described in WO2020/145133.

The F polymer is preferably a polymer with polar functional groups comprising TFE units and PAVE units, preferably a polymer comprising TFE units, PAVE units and units based on monomers with polar functional groups, all units 90 to 99 mol %, 0.5 to 9.97 mol %, and 0.01 to 3 mol % of these units in this order. The presence of a polar functional group is preferable from the viewpoint of further improving the affinity and adhesion with the first polyimide. Such polar functional groups are preferably carbonyl group-containing groups. Further, the monomer having a polar functional group is preferably itaconic anhydride, citraconic anhydride or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"). Specific examples of such F polymers include the polymers described in WO2018/16644.
Such F polymer has excellent affinity with polyimide, and tends to be more densely and homogeneously distributed in the polyimide film obtained from the present composition. In addition, since microspherulites are easily formed in the polyimide film and adhesion with other components is easily enhanced, it is easier to obtain a polyimide film excellent in various physical properties such as electrical properties.

The first polyimide in the present composition is a unit based on a tetracarboxylic dianhydride and a diamine, and a unit formed by an imidization reaction of both compounds (a unit having an imide structure; hereinafter, also referred to as an "imide unit" ), and at least one of tetracarboxylic dianhydride and diamine, and at least part of it is an aromatic compound.
The first polyimide may be an aromatic polyimide consisting only of imide units, and a unit formed by an amidation reaction between the imide unit and the above-described compounds (a unit having an amic acid structure; hereinafter referred to as "amic acid It may be an aromatic polyimide precursor (aromatic polyamic acid) having a unit (also referred to as "unit"), and is more preferably an aromatic polyimide precursor.
When the first polyimide is an aromatic polyimide precursor and the F polymer has a polar functional group, the two form crosslinks during thermoforming, which is preferable in that a dense polyimide film can be obtained.
Each of the tetracarboxylic dianhydride and the diamine may be used alone or in combination of two or more. As tetracarboxylic dianhydride, preference is given to using at least one aromatic tetracarboxylic dianhydride.

Tetracarboxylic dianhydride forming the first polyimide is preferably an aromatic tetracarboxylic dianhydride, specifically pyromellitic dianhydride, 3,3'4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'- biphenyl ether tetracarboxylic dianhydride, 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2 -bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 3 ,4,9,10-perylenetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,3 ',4,4'-benzophenonetetracarboxylic dianhydride, 2,3,2',3'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride , 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,4,5-naphthalenetetracarboxylic dianhydride, 1 ,4,5,8-naphthalenetetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4, 5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic Acid dianhydride, bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride, bis(3,4-dicarboxyphenyl)methylphenylsilane dianhydride, bis(3,4-dicarboxyphenyl)diphenylsilane Dianhydride, 1,4-bis(3,4-dicarboxyphenyldimethylsilyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyl Dicyclo Hexane dianhydride, p-phenylene bis (trimellitic monoester acid anhydride), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis[4-( 3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 4,4-bis(3,4 -dicarboxyphenoxy)diphenyl sulfide dianhydride.

As the tetracarboxylic dianhydride constituting the first polyimide, the following tetracarboxylic dianhydride having an alicyclic structure may be used.

Diamines forming the first polyimide include aromatic diamines or aliphatic diamines. The aromatic diamines include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3′- diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyldifluoromethane, 4,4'-diaminodiphenyldifluoromethane, 3,3'-diaminodiphenylsulfone, 3, 4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl ketone, 2,2-bis(3-aminophenyl)propane, 2,2-(3,4'-diaminodiphenyl)propane, 2, 2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-(3,4′-diaminodiphenyl)hexafluoropropane, 2,2-bis(4 -aminophenyl)hexafluoropropane, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 3,3′-[1,4-phenylenebis(1-methyl ethylidene)]bisaniline, 3,4′-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4′-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 2,2 -bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]hexa Fluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide , bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,3-bis(4-aminophenoxy)propane, 1,4-bis(4- aminophenoxy)butane, 1,5-bis(4-aminopheno oxy)heptane.

Aliphatic diamines include dimer diamine, alkylenediamine (2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 2,7-dimethyl-1,8-octanediamine, etc.), alicyclic Formula diamines (1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-amino cyclohexyl)propane, 2,2-bis(4-aminocyclohexyl)hexafluoropropane, isophoronediamine, norbornanediamine, etc.).
The use of an aliphatic diamine not only makes the above tendency more likely to occur, but also facilitates the expression of F polymer physical properties (especially electrical physical properties such as dielectric constant and dielectric loss tangent) in molded products at a high level, further improving flexibility. It's easy to do.

Specific examples of the first polyimide include the "Neoprim" series (manufactured by Mitsubishi Gas Chemical Company), the "Spixeria" series (manufactured by Somar), the "Q-PILON" series (manufactured by P.I. Institute of Technology), and the "WINGO" series. (manufactured by Wingo Technology), "Tomide" series (manufactured by T&K TOKA), "KPI-MX" series (manufactured by Kawamura Sangyo), and "Upia-AT" series (manufactured by Ube Industries).

The melting temperature of the first polyimide is within the range of the melting temperature of the F polymer ±50°C, preferably within the range of the melting temperature of the F polymer ±30°C. In this case, the affinity with the F polymer tends to increase, which is preferable.
When the first polyimide is an aromatic polyimide precursor, the melting temperature of the first polyimide means the melting temperature of the polyimide in which the precursor is completely imidized.

The first polyimide may be used in its varnish form to make up the composition. Solvents constituting such varnish include, for example, N-methyl-2-pyrrolidone and cyclohexanone.

The imidization rate of the first polyimide is preferably 10% or more, more preferably 25% or more, still more preferably 50% or more, and particularly preferably 75% or more. If the imidization rate is within this range, the polarity (dissociative protons) of the polyimide is further lowered, and the dispersibility of the F polymer is more likely to be promoted.
The imidization rate is preferably less than 100%, more preferably 98% or less, even more preferably 96% or less. If the imidization rate is in such a range, the polyimide promotes the interaction of each component (solvent and F polymer) while sufficiently maintaining its polarity (dissociative protons), and the physical properties of the composition (viscosity, thixotropy , etc.) can be further improved.
The imidization rate of polyimide can be controlled by the production conditions. For example, using a dehydrator such as Dean Stark, the tetracarboxylic dianhydride and the diamine are reacted in the presence of a solvent that is azeotropic with water (such as toluene) while removing by-product water by azeotropy. For example, polyimide with any imidization rate can be produced.

The imidization ratio in the present invention 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 number of moles of imide units/(the number of moles of amic acid units + the number of imide units). number of moles). In other words, when the polyimide consists only of imide units, the imidization rate is 100%. The imidization rate of the polyimide or its precursor (polyamic acid) is measured by ¹ H-NMR using dimethyl sulfoxide-d ₆ as a solvent, and the integral value of the aromatic proton peak and the integral value of the carboxylic acid proton peak. can be calculated according to the following formula (I).
Imidation rate (%) = [1-(Y/Z) x (1/X)] x 100 (I)
X: Integral value of carboxylic acid proton peak/integral value of aromatic proton peak when imidization rate is 0%, obtained from amount of charged monomer 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

In the present composition, the content of F particles is 10% by mass or more, preferably 15% by mass or more. The content of F particles is preferably 90% by mass or less, more preferably 80% by mass or less.
In the present composition, the content of the first polyimide is 10% by mass or more, more preferably 15% by mass or more. The content of the first polyimide is preferably 80% by mass or less, more preferably 60% by mass or less.
In the present composition, the ratio of the mass of the F particles to the mass of the first polyimide is preferably in the range of 0.5-4, more preferably 2-3.5. Within this range, when the composition is mixed with the second polyimide varnish to be described later, the dispersibility of the F particles is likely to be improved, and a uniform and dense polyimide film is likely to be obtained.

For mixing the F particles and the first polyimide varnish, it is preferable to use a mixing apparatus equipped with a stirring vessel and uniaxial or multiaxial stirring blades. From the viewpoint of the stirring effect, the number of stirring blades is preferably two or more. The mixing method may be batch type or continuous type.
The F particles and the first polyimide varnish may be mixed by mixing the mixture of the F particles and the liquid dispersion medium with the first polyimide varnish. Liquid dispersion media include, for example, at least one polar compound selected from water, amides, ketones, glycols and esters.

For batch mixing, a Henschel mixer, a pressure kneader, a Banbury mixer or a planetary mixer is preferred, and a planetary mixer is more preferred. The planetary mixer has two stirring blades that rotate and revolve mutually, and has a structure for stirring and kneading the kneaded material in the stirring vessel. Therefore, there is little dead space in the agitation tank that the agitating blades do not reach, and the load on the agitating blades is reduced, so that the contents can be mixed to a high degree. Also, after mixing is complete, the resulting composition can be subsequently mixed with a second polyimide varnish to produce a mixture for making a polyimide film.
Examples of continuous mixing devices include a twin-screw extrusion kneader and a stone mill type kneader. A twin-screw extrusion kneader is, for example, a twin-screw type continuous kneading device that kneads a material to be kneaded by shearing force between two screws arranged in parallel and close to each other. A stone mill type kneader has, for example, a cylindrical fixed part with an internal space through which the material to be kneaded can pass, and a continuous material to be kneaded that is placed in the internal space of the fixed part and that passes through the internal space by rotating. It is a kneader having a rotating part that conveys the material in the direction of the rotation axis while kneading the material.

The composition may or may not further contain a surfactant.
When the present composition contains a surfactant, its content is preferably 1 to 15% by mass, and the surfactant is preferably nonionic.
The hydrophilic portion of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group.
The hydrophobic portion of the surfactant preferably has an acetylene group, polysiloxane group, perfluoroalkyl group or perfluoroalkenyl group. In other words, the surfactant is preferably an acetylene-based surfactant, a silicone-based surfactant, or a fluorine-based surfactant, and more preferably a silicone-based surfactant. Specific examples of such surfactants include "Futhergent" series (manufactured by Neos), "Surflon" series (manufactured by AGC Seimi Chemical), "Megafac" series (manufactured by DIC), "Unidyne" series (Daikin Kogyosha), "BYK-347", "BYK-349", "BYK-378", "BYK-3450", "BYK-3451", "BYK-3455", "BYK-3456" (BYK-Chemie Japan Co., Ltd.), “KF-6011” and “KF-6043” (manufactured by Shin-Etsu Chemical Co., Ltd.).

The present composition may further contain a resin material other than the F polymer and the first polyimide from the viewpoint of improving the adhesion and low linear expansion properties of the polyimide film obtained from the present composition. Such resinous materials may be thermoset or thermoplastic, may be modified, may be dissolved in the composition of matter, or may be dispersed without being dissolved.
Examples of such resin materials include tetrafluoroethylene-based polymers other than F polymer, aromatic maleimides, acrylic resins, phenolic resins, liquid crystalline polyesters, liquid crystalline polyesteramides, polyolefin resins, modified polyphenylene ethers, polyfunctional cyanate ester resins, poly functional maleimide-cyanate ester resins, polyfunctional maleimides, aromatic elastomers such as styrene elastomers, vinyl ester resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, melamine-urea cocondensation resins, polycarbonates, polyarylates , polysulfone, polyallylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, polyphenylene ether, epoxy resin, and the like.
When the composition further contains a resin material, the content thereof is preferably 40% by mass or less with respect to the mass of the entire composition.

Preferred embodiments of the resin material include aromatic polymers other than the first polyimide. Such aromatic polymers include aromatic maleimides, polyphenylene ethers and aromatic elastomers (such as styrene elastomers).
In this case, not only is the adhesiveness and low linear expansion property of the polyimide film formed using the present composition further improved, but also the liquid physical properties (viscosity, thixotropic ratio, etc.) of the present composition are balanced. Easy to improve handling.
Examples of styrene elastomers include copolymers of styrene and conjugated dienes or (meth)acrylic acid esters (styrene-butadiene rubbers, styrene core-shell copolymers, styrene block copolymers, etc.). A styrene elastomer that has both properties and is plasticized by heating to exhibit flexibility is preferred.

The composition may further contain an inorganic filler. In this case, the inorganic filler tends to enhance the interaction with the F polymer, and the polyimide film formed using the present composition tends to have excellent electrical properties and low linear expansion.

The inorganic filler is preferably a nitride filler or an inorganic oxide filler, such as boron nitride filler, beryllia filler (beryllium oxide filler), silicate filler (silica filler, wollastonite filler, talc filler), or metal Oxide (cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.) fillers are more preferred, and silica fillers are even more preferred.
At least part of the surface of the inorganic filler contains a silane coupling agent (3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3 -methacryloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.).

D50 of the inorganic filler is preferably 20 µm or less, more preferably 10 µm or less. D50 is preferably 0.01 μm or more, more preferably 0.1 μm or more.
The shape of the inorganic filler may be any of granular, needle-like (fibrous), and plate-like. Specific shapes of the inorganic filler include spherical, scaly, layered, leaf-like, apricot kernel-like, columnar, crest-like, equiaxed, leaf-like, mica-like, block-like, tabular, wedge-like, rosette-like, and network. shape and prismatic shape.
An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

Preferable specific examples of inorganic fillers include silica fillers (“ADMAFINE (registered trademark)” series manufactured by Admatechs), zinc oxide surface-treated with an ester such as propylene glycol dicaprate (Sakai Chemical Industry Co., Ltd. "FINEX (registered trademark)" series manufactured by Denka), spherical fused silica ("SFP (registered trademark)" series manufactured by Denka, etc.), titanium oxide coated with polyhydric alcohol and inorganic substances (manufactured by Ishihara Sangyo Co., Ltd. "Tipake (registered trademark)" series, etc.), rutile-type titanium oxide surface-treated with alkylsilane ("JMT (registered trademark)" series, manufactured by Tayca Corporation, etc.), hollow silica filler ("E -SPHERES" series, Nittetsu Mining Co., Ltd.'s "Silinax" series, Emerson & Cumming Co.'s "Ecocospear" series, etc.), Talc filler (Nippon Talc Co., Ltd.'s "SG" series, etc.), Steatite filler ( Nippon Talc "BST" series, etc.), boron nitride filler (Showa Denko "UHP" series, Denka "Denka Boron Nitride" series ("GP", "HGP" grade), etc.) mentioned.

In addition to the above components, the present composition may contain a thixotropic agent, a viscosity modifier, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, and an antioxidant within a range that does not impair the effects of the present invention. Other ingredients such as agents, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, flame retardants, and various fillers may be further included.

The present composition containing F particles and the first polyimide and the second polyimide varnish are mixed and molded by a casting method to produce a polyimide film (hereinafter also referred to as "present polyimide film"). can.
In this polyimide film, the F polymer is highly dispersed in the first polyimide and the second polyimide, and the uniformity and density of the component distribution are excellent. Excellent properties derived from polymers, namely, various physical properties such as adhesion and electrical properties. Above all, these effects are more pronounced when the F polymer having a polar functional group, especially a carbonyl group-containing group is used.

Such a second polyimide is a unit based on a tetracarboxylic dianhydride and a diamine, and has an imide unit formed by the imidization reaction of both compounds.
The second polyimide may be a polyimide consisting only of imide units, or may be a polyimide precursor (polyamic acid) having imide units and amic acid units. Each of the tetracarboxylic dianhydride and the diamine may be used alone or in combination of two or more. Specific examples of the tetracarboxylic dianhydrides and diamines include compounds similar to the tetracarboxylic dianhydrides and diamines that can constitute the first polyimide. Specific examples of the second polyimide include those similar to those of the first polyimide.
Examples of solvents that constitute the second polyimide varnish include N-methyl-2-pyrrolidone and cyclohexanone.

Different types of the first polyimide and the second polyimide may be used, or the same polyimide may be used. When different kinds of polyimides are used, the melting temperature of the first polyimide is preferably lower than the melting temperature of the second polyimide from the viewpoint of obtaining a dense polyimide film. When the second polyimide is a polyimide precursor, the melting temperature of the second polyimide means the melting temperature of the polyimide in which the precursor is completely imidized.
Further, the melting temperature of the first polyimide is preferably 100° C. or higher than the boiling point of the solvent contained in the second polyimide varnish, from the viewpoint of obtaining a dense present polyimide film, and is preferably 120° C. or higher. more preferred.

The content of the F particles in the mixture of the present composition and the second polyimide varnish is preferably 0.1% by mass or more, more preferably 1% by mass or more. The content of F particles is preferably 40% by mass or less, more preferably 30% by mass or less.
The ratio of the content of the F particles to the total content of the first polyimide and the second polyimide in the mixture is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.2 or less. The content ratio of the F particles is preferably 0.01 or more, more preferably 0.05 or more.

As the casting method, known methods such as die coater, reverse coater, blade coater, etc. can be applied, and the prepared liquid film is heated at a temperature of 70 to 200° C. and dried. Upon heating, if the first polyimide and the second polyimide are polyimide precursors, some or all of the amic acid units are converted to imide units.
The thickness of the present polyimide film can be appropriately adjusted according to its use, and is generally preferably in the range of 10 to 200 μm, more preferably in the range of 30 to 150 μm.

The content of the F polymer in the present polyimide film is preferably 0.1% by mass or more, more preferably 1% by mass or more. The content of the F polymer is preferably 40% by mass or less, more preferably 20% by mass or less.
In the present polyimide film, the ratio of the content of the F polymer to the total content of the first polyimide and the second polyimide is preferably 1 or less, more preferably 0.5 or less, and further preferably 0.2 or less. . The content ratio of the F polymer is preferably 0.01 or more, more preferably 0.05 or more.

By forming a layer of a tetrafluoroethylene-based polymer on at least one surface of the present polyimide film obtained above, a layer composed of the present polyimide film and a layer of a tetrafluoroethylene-based polymer on at least one surface thereof. A composite film (hereinafter also referred to as "this composite film") can be produced. This composite film is excellent in low linear expansion, low water absorption, low dielectric constant and low dielectric loss tangent. The reason for this is not necessarily clear, but is presumed as follows, for example.
Since the polyimide film contains polyimide, which has a high affinity with other components, and the F polymer, which is the same type of polymer as the tetrafluoroethylene-based polymer, the polyimide film and the tetrafluoroethylene-based polymer layer adhere well. do. As a result, the composite film exhibits excellent physical properties such as low dielectric constant, low dielectric loss tangent, and low water absorption derived from the tetrafluoroethylene polymer, and also exhibits excellent physical properties such as low linear expansion derived from the polyimide. expressed in

Examples of the method for producing the present composite film include a method of forming a layer of the tetrafluoroethylene polymer by laminating a tetrafluoroethylene polymer film on at least one surface of the present polyimide film obtained above. be done.
As the tetrafluoroethylene-based polymer, polytetrafluoroethylene (PTFE) may be used in addition to the F polymer described above. For example, these polymers are melt-kneaded and extruded to obtain a tetrafluoroethylene-based polymer film, or a dispersion containing tetrafluoroethylene-based polymer particles and a dispersion medium is applied to a substrate and heated. A film of tetrafluoroethylene-based polymer may be obtained by peeling. The composite film is obtained by laminating (thermocompression bonding) such a film to at least one surface of the polyimide film.

Lamination means include, for example, a hot roll lamination device having metal rolls, or a method using a continuous process using a double belt press. The heating method is not particularly limited, and conventionally known methods capable of heating at a predetermined temperature, such as a heat circulation method, a hot air heating method, and an induction heating method, can be employed. The pressurizing means is also not particularly limited, and known means capable of applying a predetermined pressure, such as hydraulic pressure, pneumatic pressure, and pressure between gaps, can be employed. The lamination temperature is preferably the glass transition temperature of the completely imidized first polyimide and the glass transition temperature of the second polyimide, which is the lower glass transition temperature +50 ° C. or higher, and +100 ° C. or higher. It is preferable to have

The present composite film is also obtained by applying a dispersion containing a tetrafluoroethylene-based polymer (hereinafter also simply referred to as "F dispersion") to at least one surface of the present polyimide film to form a liquid coating, and this liquid coating is heated to remove the dispersion medium to form a dry film, and the dry film is heated and baked to form a polymer layer containing a tetrafluoroethylene-based polymer (hereinafter also referred to as "F layer"). It can also be produced by a method of forming on the surface of a polyimide film.

As the tetrafluoroethylene-based polymer contained in the F dispersion, polytetrafluoroethylene (PTFE) may be used in addition to the above-described F polymer contained in the present composition. The F dispersion may be a dispersion in which the F particles containing the F polymer are dispersed, or may be a dispersion in which PTFE particles are dispersed. When the F dispersion contains F particles, the preferred ranges of D50, D90 and bulk density of the F particles, and the resin and inorganic filler that the particles may further contain are the same as those described above for the F particles.

The dispersion medium in Dispersion F is preferably a compound that is liquid at 25° C. under atmospheric pressure, more preferably at least one polar compound selected from water, amides, ketones and esters. The boiling point of the dispersion medium is preferably in the range of 50 to 240°C. A dispersion medium may be used individually by 1 type, and may use 2 or more types together.
As the dispersion medium, water, 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, methyl ethyl ketone. Incidentally, the dispersion medium may contain a non-polar solvent such as toluene.
The content of the dispersion medium in the F dispersion is preferably 30 to 90% by mass, more preferably 50 to 80% by mass.

The F dispersion can be prepared, for example, by adding particles of a tetrafluoroethylene polymer to a dispersion medium all at once or in portions and mixing them. When a surfactant, an inorganic filler, or another resin material is further included, it is added at the same time when the F particles are dispersed in the dispersion medium, or is added in advance to the dispersion medium before the tetrafluoroethylene polymer particles are dispersed. It is preferable to keep Mixing means include a stirring device equipped with uniaxial or multiaxial blades (stirring blades) such as propeller blades, turbine blades, paddle blades, shell-shaped blades, Henschel mixer, pressure kneader, Banbury mixer or planetary mixer. Stirring; using media such as ball mill, attritor, basket mill, sand mill, sand grinder, dyno mill (bead mill using grinding media such as glass beads or zirconium oxide beads), Dispermat, SC mill, spike mill or agitator mill Mixing by dispersing machine: Mixing using a dispersing machine that does not use media, such as a high-pressure homogenizer such as a microfluidizer, a nanomizer, or an ultimizer, an ultrasonic homogenizer, a desolver, a disper, or a high-speed impeller dispersing machine.

The F dispersion may further contain a surfactant. When the F dispersion contains a surfactant, its content is preferably 1 to 15% by mass, and the surfactant is preferably nonionic. Specific examples of the surfactant include the same surfactants as those described above that may be contained in the present composition.

The F dispersion may further contain an inorganic filler. In this case, the F layer (molded product/fired product) produced from the F dispersion tends to be excellent in electrical properties and low linear expansion. Examples of inorganic fillers include the same inorganic fillers as those described above that may be contained in the present composition.

From the viewpoint of improving the adhesiveness and low linear expansion property of the F layer (molded article) formed from the F dispersion, the F dispersion preferably further contains a resin material other than the tetrafluoroethylene-based polymer.
Examples of such resin materials include the above resin materials that may be contained in the present composition, aromatic polyimides or precursors thereof, aromatic polyamideimides or precursors thereof, and aromatic maleimides. Preferred are aromatic polymers, preferably aromatic polyimides, aromatic polyamideimides or precursors thereof, more preferably thermoplastic aromatic polyimides.
Specific examples of the aromatic polyimide include those similar to the specific examples of the first polyimide. Specific examples of aromatic polyamide-imides include the "HPC" series (manufactured by Showa Denko Materials). In this case, the interlayer adhesion and low linear expansion property between the F layer (molded article) formed from the F dispersion and the present polyimide film are further improved. In addition, the liquid physical properties (viscosity, thixotropic ratio, etc.) of the F dispersion are well-balanced, and the handleability is easily improved. These may be dissolved in the F dispersion, or may be dispersed without being dissolved.
When the F dispersion contains the resin material described above, the content thereof is preferably 40% by mass or less, more preferably 10% by mass or less, relative to the entire F dispersion. The content is preferably 0.1% by mass or more, more preferably 1% by mass or more.

Dispersion F contains, in addition to the above components, a thixotropic agent, a viscosity modifier, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, and an antistatic agent. Other components such as agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, flame retardants, and various fillers may be further included.

The viscosity of the F dispersion is preferably 50 mPa·s or more, more preferably 100 mPa·s or more, and even more preferably 300 mPa·s or more. The viscosity of the F dispersion is preferably 10000 mPa·s or less, more preferably 5000 mPa·s or less, and even more preferably 1000 mPa·s or less. In this case, the F dispersion is excellent in coatability and easily forms an F layer having an arbitrary thickness.
The thixotropic ratio of the F dispersion is preferably 1.0 or more. The thixotropic ratio of the F dispersion is preferably 3.0 or less, more preferably 2.0 or less. In this case, the F dispersion is excellent in coatability and homogeneity, and easily forms a denser F layer.

The content of the tetrafluoroethylene-based polymer particles in the F dispersion is preferably 10% by mass or more, more preferably 15 to 80% by mass, relative to the total mass of the F dispersion. The F layer (formed article such as a coating film) can be formed from the dispersion liquid with high uniformity, and the physical properties of the tetrafluoroethylene-based polymer can be highly exhibited.

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

When drying the liquid coating, the liquid coating is heated at a temperature at which the dispersion medium volatilizes to form a dry coating on the surface of the present polyimide film. The temperature for such heating is preferably +50° C. or lower than the boiling point of the dispersion medium, more preferably equal to or lower than the boiling point of the dispersion medium, and even more preferably −50° C. or lower. The temperature during drying is preferably 120°C to 200°C. Air may be blown in the step of removing the dispersion medium.
During drying, the dispersion medium does not necessarily have to be completely volatilized, and may be volatilized to such an extent that the layer shape after retention is stable and a self-supporting film can be maintained.

When baking the tetrafluoroethylene-based polymer in the F dispersion, it is preferable to heat the dry film at a temperature equal to or higher than the melting temperature of the tetrafluoroethylene-based polymer. The heating temperature is preferably 380° C. or lower, more preferably 350° C. or lower.
Examples of heating methods include a method using an oven, a method using a ventilation drying oven, and a method of irradiating heat rays such as infrared rays. Heating may be performed under normal pressure or under reduced pressure. The heating atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). .
The heating time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.
By heating under the above conditions, the F layer can be suitably formed while maintaining high productivity.

The thickness of the F layer is preferably 0.1-150 μm, more preferably 10-50 μm.
The ratio of the thickness of the F layer to the thickness of the present polyimide film is preferably 0.2 or more, more preferably 0.4 or more. 5 or less is preferable, and 3 or less is more preferable.
The peel strength between the F layer and the present polyimide film is preferably 10 N/cm or more, more preferably 15 N/cm or more. The peel strength is preferably 100 N/cm or less.
When the F layer further contains an aromatic polymer, the ratio of the aromatic polymer content to the tetrafluoroethylene-based polymer content in the F layer is more preferably 0.4 or less, more preferably 0.2 or less. It is preferred, and 0.1 or less is more preferred. The content ratio is preferably 0.001 or more, more preferably 0.01 or more.

The F layer may be applied to only one surface of the present polyimide film, or may be applied to both surfaces. In the former, a composite film having the present polyimide film and an F layer on one surface of the present polyimide film is obtained, and in the latter, a composite film having the present polyimide film and an F layer on both surfaces of the present polyimide film is obtained. be done. The latter composite film is more resistant to warping, and is therefore excellent in handleability during processing.

Another substrate may be further laminated on the outermost surface of the composite film.
Other substrates include a metal foil, a heat-resistant resin film, a prepreg that is a precursor of a fiber-reinforced resin plate, a laminate having a heat-resistant resin film layer, and a laminate having a prepreg layer.
A prepreg is a sheet-like substrate obtained by impregnating a base material (tow, woven fabric, etc.) of reinforcing fibers (glass fiber, carbon fiber, etc.) with a thermosetting resin or thermoplastic resin.
A heat-resistant resin film is a film containing one or more heat-resistant resins, and examples of heat-resistant resins include the resins described above. As a lamination method, there is a method of hot-pressing the present composite film and another substrate.

As described above, by using the present composition, it is possible to obtain a polyimide film having excellent uniform distribution of components and excellent electrical properties. Also, a composite film containing an F layer on at least one side of the resulting polyimide film is obtained. Such a composite film can be effectively used as a material for printed wiring boards, particularly flexible printed wiring boards, and exhibits excellent physical properties of the F polymer.

Although the present composition, the method for producing a polyimide film using the present composition, and the method for producing a composite film containing such a polyimide film have been described above, the present invention is not limited to the configurations of the above-described embodiments.
For example, the present composition may additionally have other optional steps in the configuration of the above embodiments, or may be replaced with any steps that produce similar effects. In addition, the method for producing a polyimide film using the present composition and the method for producing a composite film containing such a polyimide film may be added with any other configuration in the configuration of the above embodiment, and exhibit the same function. may be replaced with any configuration that

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
1. Details of each component [F particles]
F particle 1: 97.9 mol%, 0.1 mol% and 2.0 mol% of TFE units, NAH units and PPVE units in this order, and a carbonyl group-containing group per 1 × 10 ⁶ main chain carbon atoms Particles (D50: 2.1 μm) made of F polymer 1 (melting temperature: 300° C.) having 1000 particles
[Liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone CHN: cyclohexanone [polyimide or its precursor varnish]
Varnish 1: Varnish containing precursor of thermoplastic aromatic polyimide (polyimide 1; hereinafter referred to as PI1) (solvent: CHN)
Varnish 2: Varnish containing thermoplastic aromatic polyimide (polyimide 2; hereinafter referred to as PI2) (solvent: NMP)
The melting temperatures of the polyimides obtained by completely imidizing PI1 and PI2 are both in the range of 270 to 330 ° C., and the melting temperature of the polyimide obtained by completely imidizing PI1 is below the melting temperature of
[Surfactant]
Surfactant 1: A nonionic fluorine-based surfactant having a fluorine-containing alkyl group and a hydroxyl group and having a fluorine content of 35% by mass.

2. Production of polyimide film [Example 1-1]
F particles 1 and varnish 1 are put into a planetary mixer and kneaded to obtain composition 1 containing F particles 1 (3 parts by mass), PI1 (10 parts by mass), and CHN (7 parts by mass) (viscosity: 20000 mPa·s) was obtained.
Subsequently, varnish 2 is added to composition 1 in multiple portions and stirred, and F particles 1 (3 parts by mass), PI1 (10 parts by mass), PI2 (20 parts by mass), CHN (7 parts by mass) ) and NMP (60 parts by mass) to obtain a mixture 1 (viscosity: 400 mPa·s).
The obtained mixture 1 was applied on a glass plate and then heated at 90° C. for 30 minutes to remove the solvent, thereby obtaining a sheet 1. Sheet 1 was peeled off the glass plate and pinned to a metal frame. Sheet 1 was heated in a metal frame at 350° C. for 10 minutes. As a result, a film 1 (thickness: 50 μm) containing the imidized products of PI1 and PI2 and the melt-sintered product of the F particles 1 was obtained.

3. Production of composite film [Example 1-2]
On one side of the film 1, a dispersion 1 containing F particles 1 (20 parts by mass), PI2 (1 part by mass), surfactant 1 (3 parts by mass) and NMP (75 parts by mass) is applied by a small diameter gravure reverse method. and passed through a ventilation drying oven (furnace temperature 150° C.) for 3 minutes to remove NMP and form a dry film. Similarly, the dispersion liquid 1 was applied to the other surface of the film 1 and dried to form a dry film.
Next, the film 1 with the dry coatings formed on both sides is passed through a far-infrared furnace (furnace temperature of 300° C. near the entrance and exit of the furnace, and furnace temperature of 340° C. near the center) for 20 minutes. The F particles 1 were melted and sintered.
As a result, a polymer layer (thickness: 25 μm) containing the fused sintered product of F particles 1 and the imidized product of PI2 was formed on both surfaces of the film 1, and the polymer layer, the film layer, and the polymer layer were directly formed in this order. A film (composite film 1) was obtained.
When the surface of the polymer layer of Composite Film 1 was visually observed, it was highly smooth and no pinholes were observed. In addition, a rectangular (100 mm long, 10 mm wide) test piece was cut out from the composite film 1, the position of 50 mm from one end in the length direction of the test piece was fixed, and the tensile speed was 50 mm / min, from one end in the length direction. The polymer and film layers were peeled apart at 90° to the specimen. The maximum load applied at that time was 15 N/cm or more, and the composite film 1 was excellent in interlayer adhesion.

The compositions of the present invention are useful for making polyimide films in which the F polymer is well dispersed. Moreover, a composite film having a substrate layer made of such a polyimide film and a layer made of a tetrafluoroethylene-based polymer can be easily processed into a prepreg or a metal laminate (resin-coated metal foil). The processed articles obtained can be used as materials for antenna parts, printed wiring boards, aircraft parts, automobile parts, sporting goods, food industry goods, plain bearings, and the like.

Claims (15)

A composition containing an aromatic polyimide or a precursor thereof and particles of a heat-melting tetrafluoroethylene-based polymer each in an amount of 10% by mass or more, wherein the melting temperature of the aromatic polyimide is the heat-melting tetrafluoro A composition having a melting temperature of an ethylene polymer within a range of ±50° C. and used by mixing with a polyimide or its precursor varnish. The composition according to claim 1, wherein the hot-melt tetrafluoroethylene-based polymer has a melting temperature of 200 to 320°C. 3. The composition according to claim 1, wherein the heat-meltable tetrafluoroethylene-based polymer particles have an average particle diameter (volume-based cumulative 50% diameter) of 0.1 to 25 μm. 4. Any one of claims 1 to 3, wherein the mass ratio of the particles of the hot-melt tetrafluoroethylene-based polymer to the mass of the aromatic polyimide or its precursor is in the range of 0.5 to 4. The composition according to . The composition according to any one of claims 1 to 4, wherein the aromatic polyimide has a melting temperature equal to or lower than the melting temperature of the polyimide constituting the varnish. The composition according to any one of claims 1 to 5, wherein the melting temperature of the aromatic polyimide is 100°C or more higher than the boiling point of the solvent contained in the varnish. A composition according to any preceding claim, wherein the aromatic polyimide or precursor is a precursor of an aromatic polyimide. The composition according to any one of claims 1 to 7, wherein the hot-melt tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a carbonyl group-containing group containing units based on perfluoro(alkyl vinyl ether). . A method for producing a polyimide film, comprising mixing the composition according to any one of claims 1 to 8 with a polyimide or a varnish of its precursor, and molding the mixture by a casting method to obtain a polyimide film. Forming a tetrafluoroethylene-based polymer layer on at least one surface of the polyimide film obtained by the production method according to claim 9, the polyimide film and a tetrafluoroethylene-based polymer layer on at least one surface thereof A method for manufacturing a composite film comprising: 11. The method for producing a composite film according to claim 10, wherein the tetrafluoroethylene-based polymer layer is formed by laminating a tetrafluoroethylene-based polymer film on at least one surface of the polyimide film. The composite film according to claim 10, wherein the tetrafluoroethylene polymer layer is formed by applying a dispersion containing tetrafluoroethylene polymer particles to at least one surface of the polyimide film and heating it. Production method. 13. The method for producing a composite film according to claim 12, wherein the dispersion contains aromatic polyimide, aromatic polyamideimide, or precursors thereof. A composite film obtained by the production method according to any one of claims 10 to 13. A printed wiring board comprising a composite film obtained by the manufacturing method according to any one of claims 10 to 13.