JP7443969B2 - Extrusion film manufacturing method and extrusion film - Google Patents

Description

The present invention relates to a method for producing an extruded film and an extruded film.

Tetrafluoroethylene-based polymers have low dielectric constants and dielectric loss tangents, so they are used for electrical insulating layers of printed wiring boards that transmit high-frequency signals. In printed wiring boards, a through hole is formed in a laminate with conductors on both sides of an electrical insulator layer, and a plating layer is formed on the inner wall of the through hole to ensure continuity between the conductors. There are many. A UV-YAG laser is used to form the through holes.
Furthermore, tetrafluoroethylene polymers have low absorption in the UV wavelength region. Therefore, in printed wiring boards having a layer of tetrafluoroethylene polymer, high-power laser irradiation is required to form through holes. As a result, the layers and conductors are deformed by the heat generated during laser irradiation, and delamination or the like is likely to occur.

In Patent Document 1, a UV absorber is included in the film to improve the processability of hole punching using a UV-YAG laser, but the UV absorber deteriorates the electrical properties of the film, such as the electrical insulation properties.
In Patent Document 2, the tetrafluoroethylene-based polymer is treated at high temperature to improve the workability of hole-drilling with UV-YAG laser, but a manufacturing device suitable for high-temperature treatment is required.

Special Publication No. 4-503081 International Publication 2019/087939

The inventors of the present invention have conducted intensive studies to obtain a film that has both good electrical properties and good workability for perforation using a UV-YAG laser. As a result, a film obtained by melt-extruding a mixture of a melt-kneaded product of particles of a predetermined tetrafluoroethylene polymer and particles of a predetermined aromatic polymer, and particles of a predetermined tetrafluoroethylene polymer was obtained. It was discovered that the physical properties of both are excellent. Furthermore, this film had excellent adhesion to other materials.

The present invention has the following aspects.
<1> A melt-kneaded product of particles of a first tetrafluoroethylene polymer having a melting temperature of 270 to 320°C and particles of an aromatic polymer having an average particle diameter of 1 to 10 μm, and a mixture having a melting temperature of 270 to 320°C. A method for producing an extruded film, comprising melt-extruding a mixture with particles of a second tetrafluoroethylene polymer to obtain an extruded film containing 10% by mass or less of the aromatic polymer.
<2> A tetrafluoroethylene polymer in which the first tetrafluoroethylene polymer and the second tetrafluoroethylene polymer each independently contain a unit based on perfluoro(alkyl vinyl ether) and have a polar functional group; Alternatively, the method for producing <1>, which is a tetrafluoroethylene polymer containing 2.0 to 5.0 mol% of units based on perfluoro(alkyl vinyl ether) based on the total units and having no polar functional group.
<3> The manufacturing method of <1> or <2>, wherein the first tetrafluoroethylene polymer and the second tetrafluoroethylene polymer are the same tetrafluoroethylene polymer.
<4> The manufacturing method according to any one of <1> to <3>, wherein the aromatic polymer is a non-thermoplastic polyimide.
<5> The manufacturing method according to any one of <1> to <4>, wherein the glass transition temperature of the aromatic polymer is in the range of the melting temperature of the first tetrafluoroethylene polymer +20° C. or higher.
<6> The manufacturing method according to any one of <1> to <5>, wherein the melt flow rate of the second tetrafluoroethylene polymer is within the range of ±7 g/10 minutes of the melt flow rate of the melt-kneaded pellets.
<7> The content of the aromatic polymer in the melt-kneaded material is 5 to 30 parts by mass based on 100 parts by mass of the first tetrafluoroethylene polymer, <1> to <6>. Any manufacturing method.
<8> The production according to any one of <1> to <7>, wherein in the mixture, a mixing ratio by mass of the second tetrafluoroethylene polymer particles to the melt-kneaded material is 5 to 20. Method.
<9> An extruded film comprising a sea domain of a tetrafluoroethylene polymer having a melting temperature of 270 to 320°C and an island domain of an aromatic polymer, wherein the content of the aromatic polymer in the extruded film is is 10% by mass or less, the average domain diameter of the island domains is 1 to 10 μm, and the transmittance of light at a wavelength of 355 nm in the extruded film having a thickness of 25 μm is 80% or less, Extruded film.
<10> The tetrafluoroethylene polymer contains a unit based on perfluoro(alkyl vinyl ether) and has a polar functional group, or the tetrafluoroethylene polymer contains 2 units based on perfluoro(alkyl vinyl ether) with respect to all units. The extruded film of <9>, which is a tetrafluoroethylene polymer containing .0 to 5.0 mol% and having no polar functional group.
<11> The extrusion film of <9> or <10>, wherein the aromatic polymer is a non-thermoplastic polyimide.
<12> The extruded film according to any one of <9> to <11>, wherein the content of the aromatic polymer is 0.1 to 5% by mass.
<13> The extruded film according to any one of <9> to <12>, wherein the difference between the maximum value and the minimum value of the transmittance is 7% or less in the plane of the extruded film having a thickness of 25 μm. .
<14> The extruded film according to any one of <9> to <13>, wherein the extruded film has a thickness more than twice the average domain diameter of the island domains.

According to the present invention, it is possible to provide a method for producing an extrusion-molded film that has excellent electrical properties and processability of perforation using a UV-YAG laser (hereinafter also referred to as "UV processability"). Furthermore, it is possible to provide an extrusion-molded film having excellent properties.

The following terms have the following meanings:
"Average particle diameter (D50)" is the volume-based cumulative 50% diameter of the target object (particles, filler) determined by laser diffraction/scattering method. In other words, the particle size distribution of the target object is measured using a laser diffraction/scattering method, a cumulative curve is determined with the total volume of the target particle population as 100%, and the particles at the point on the cumulative curve where the cumulative volume is 50% are determined. It is the diameter.
"D90" is the volume-based cumulative 90% diameter of the object, which is measured in the same manner.
"Melting temperature (melting point)" is the temperature corresponding to the maximum value of the melting peak of the polymer measured by differential scanning calorimetry (DSC).
"Glass transition point (Tg)" is a value measured by analyzing a polymer, cured product, or elastomer using a dynamic mechanical analysis (DMA) method.
"Specific surface area of particles" is determined by gas adsorption (constant volume method) BET multipoint method using NOVA4200e (manufactured by Quantachrome Instruments).
"Melt flow rate (MFR)" means the melt mass flow rate of a polymer as defined in JIS K 7210:1999 (ISO 1133:1997).
"Film thickness" is a contact thickness meter DG-525H (manufactured by Ono Sokki Co., Ltd.) using a measuring point AA-026 (Φ10 mm, SR7) to measure the thickness of the film at a distance in the width direction. This is the average value of measurements taken at 10 points so that the values are equal.
“Ten-point average roughness (Rzjis) of the surface of the metal foil layer” is a value specified in Annex JA of JIS B 0601:2013.
"Dielectric loss tangent" is a value measured at a frequency of 10 GHz in an environment of 24° C. and 50% RH using the SPDR method.
A "unit" in a polymer may be an atomic group directly formed from a monomer, or may be an atomic group whose structure is partially converted by processing the resulting polymer in a predetermined manner. A unit based on monomer A contained in a polymer is also simply referred to as a "monomer A unit."

The method for producing an extruded film of the present invention (hereinafter also referred to as "the present method") uses a first tetrafluoroethylene polymer (hereinafter also referred to as "first F polymer") having a melting temperature of 270 to 320°C. ) particles (hereinafter also referred to as "first F particles") and particles of an aromatic polymer (hereinafter also referred to as "AR polymer") with a D50 of 1 to 10 μm (hereinafter also referred to as "AR particles"). ) and particles of a second tetrafluoroethylene polymer (hereinafter also referred to as "second F polymer") that does not contain an AR polymer and has a melting temperature of 270 to 320°C. (also referred to as "second F particles") is melt-extruded to obtain an extruded film (hereinafter also referred to as "main film") containing 10% by mass or less of an AR polymer.

According to this method, a film having excellent electrical properties and UV processability can be obtained. Although the reason is not necessarily clear, it is thought to be as follows.
The film contains a small amount of AR polymer. Therefore, in this film, a sea-island structure is formed in which the domains containing the two F polymers form the sea and the domains containing the AR polymer form the islands.

In this method, a melt-kneaded product (melt-kneaded pellets) containing a first F polymer and an AR polymer is obtained, and the film is produced from this melt-kneaded product and second F particles. The melt-kneaded product can also be regarded as a masterbatch. It is thought that sufficient shear is applied to the polymer when forming the masterbatch, making it difficult for the AR polymer to aggregate, resulting in the formation of island domains of uniform size in the film. Furthermore, it is believed that when forming the present film, the AR polymer and the two F polymers are sufficiently mixed, and the island domains are uniformly dispersed in the present film, resulting in high UV absorption.

The present inventors also found that when the average domain diameter of the island domains is within a predetermined range, light rays can effectively penetrate into the island domains, so even when the content of the AR polymer in the present film is small, the present invention is effective. It has been found that the absorption of light in the film increases. The average domain diameter of the island domains formed is considered to depend on the D50 of the AR particles. In this method, the film is formed using AR particles having a predetermined D50 (1 to 10 μm). Therefore, in this film, it is considered that when the content of the AR polymer is at least, island domains having an appropriate domain diameter are formed and the film has high UV absorbability.

In this method, the first F polymer and the second F polymer are preferably the same F polymer. In this case, the first F polymer and the second F polymer are uniformly mixed during melt extrusion molding, and a homogeneous sea domain is likely to be formed in the film.
In this method, the glass transition temperature of the AR polymer is preferably in the range of the melting temperature of the first F polymer +20°C or more, and more preferably in the range of the melting temperature +30°C or more. The glass transition temperature of the AR polymer is preferably in the range of +60°C or lower than the melting temperature of the first F polymer, and more preferably in the range of +50°C or lower. In this case, regardless of the type of AR polymer, during the formation of the melt-kneaded product and the melt extrusion molding, the AR polymer is less likely to be in a molten state, and island domains with appropriate domain diameters are likely to be formed in the film. .

The MFR of the second F polymer is preferably within the range of MFR of the melt-kneaded product ±7 g/10 minutes, more preferably within the range of ±5 g/10 minutes. In this case, since the MFR of the second F polymer and the MFR of the melt-kneaded product are close to each other, when forming the main film, the AR polymer and the two F polymers are sufficiently mixed, and the island domain is formed in the film. is uniformly dispersed, and higher UV absorption can be achieved.
The content of the AR polymer in the melt-kneaded product is preferably 5 to 30 parts by weight, more preferably 10 to 20 parts by weight, based on 100 parts by weight of the first F polymer. In this case, in this film, electrical properties and UV processability are easily balanced.
In the mixture, the mixing ratio of the second F particles to the melt-kneaded material by mass is preferably 5 to 20, more preferably 5 to 10. In this case, in this film, electrical properties and UV processability are more likely to be balanced.

The first F polymer in the present invention is a polymer containing units based on tetrafluoroethylene (TFE) (TFE units). The first F polymer in the present invention is thermofusible. The melting temperature of this first F polymer is 270 to 320°C, preferably 275 to 315°C, and more preferably 290 to 310°C. In this case, the moldability of the first F polymer and the mechanical strength of the film are easily balanced.
The glass transition point of the first F polymer is preferably 75 to 125°C, more preferably 80 to 100°C.
The MFR of the first F polymer is preferably 0.5 to 100 g/10 minutes, more preferably 1 to 30 g/10 minutes. In this case, the film tends to have excellent surface smoothness, appearance, and mechanical strength.

Examples of the first F polymer include a polymer containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units), and a polymer containing units based on hexafluoropropene (HFP) (FEP). and is preferably PFA. As PAVE, CF ₂ =CFOCF ₃ , CF ₂ =CFOCF ₂ CF ₃ and CF ₂ =CFOCF ₂ CF ₂ CF ₃ (PPVE) are preferred, and PPVE is more preferred.

Preferably, the first F polymer has a polar functional group. The polar functional group may be included in a unit in the first F polymer, or may be included in a terminal group of the main chain of the first F polymer. The latter embodiment includes a first F polymer having a polar functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and a first F polymer having a polar functional group obtained by plasma treatment or ionizing radiation treatment. Examples include polymers. The polar functional group is preferably a hydroxyl group-containing group or a carbonyl group-containing group.

The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, and more preferably -CF ₂ CH ₂ OH or -C(CF ₃ ) ₂ OH.
The 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 ), and an acid anhydride residue. Groups (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.) or carbonate groups (-OC(O)O-) are preferred, and acid anhydride residues is more preferable.

The first F polymer is a polymer (1) containing a polar functional group containing a TFE unit and a PAVE unit, or a polymer containing a TFE unit and a PAVE unit and containing 2.0 to 5.0 mol of PAVE units based on the total units. %, polymers (2) without polar functional groups are preferred.
Since these polymers form microspherulites in the present film, adhesion with other components is likely to increase, and island domains having appropriate domain diameters are also likely to be formed. As a result, this film is obtained that has excellent surface smoothness, adhesiveness, electrical properties, and UV absorption (UV processability).

The polymer (1) is preferably a polymer containing TFE units, PAVE units, and units based on monomers having polar functional groups, and these units are contained in this order in an amount of 90 to 99 mol%, 0 More preferably, it is a polymer containing 0.5 to 9.97 mol%, and 0.01 to 3 mol%. Furthermore, 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 the polymer (1) include the polymers described in International Publication No. 2018/16644.

Polymer (2) consists only of TFE units and PAVE units, and contains 95.0 to 98.0 mol% of TFE units and 2.0 to 5.0 mol% of PAVE units based on the total units. is preferred. The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, based on all units.
In addition, polymer (2) does not have a polar functional group, which means that the number of polar functional groups that the polymer has is less than 500 per 1 × 10 ⁶ carbon atoms constituting the polymer main chain. means. The number of polar functional groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of polar functional groups is usually 0.

Polymer (2) may be produced using a polymerization initiator, chain transfer agent, etc. that does not produce a polar functional group as the terminal group of the polymer chain, and may be produced using a polymerization initiator or chain transfer agent that does not produce a polar functional group as the terminal group of the polymer chain. It may also be produced by fluorinating a polymer (1), etc., which has a polar functional group derived from the agent at the end group of the main chain of the polymer. Examples of the fluorination treatment method include a method using fluorine gas (see Japanese Patent Application Publication No. 2019-194314, etc.).

The first F particles in the present invention are particles containing a first F polymer, and the content of the first F polymer in the first F particles is preferably 80% by mass or more, and 100% by mass. More preferred.
The first F particles may include a different polymer than the first F polymer. Different polymers include aromatic polyesters, polyamideimides, polyimides, polyphenylene ethers, polyphenylene oxides, maleimides.
The first F particles may contain an inorganic substance. As the inorganic substance, oxides, nitrides, elemental metals, alloys and carbon are preferable, and 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) are more preferred, silica and boron nitride are even more preferred, and silica is particularly preferred. In this case, the film tends to have excellent electrical properties, low linear expansion, and UV water absorption. The F particles containing an inorganic substance preferably have an F polymer as a core and have an inorganic substance on the surface of this core. Such F particles are obtained, for example, by coalescing (colliding, aggregating, etc.) F polymer particles and inorganic particles.

The first F particles may be in the form of pellets or powder. The first F particles are preferably in powder form.
D50 of the powdered first F particles is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less. The D50 of the first F particles is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. Moreover, D90 of the first F particles is preferably less than 100 μm, more preferably 90 μm or less.
The specific surface area of the powdered first F particles is preferably 1 to 8 m ² /g, more preferably 1 to 5 m ² /g, and even more preferably 1 to 3 m ² /g.
If the D50, D90 and specific surface area of the powdered first F particles are within the above ranges, it is easy to mix them with the AR particles when forming a melt-kneaded product.

The AR polymer in the present invention is an aromatic elastomer such as liquid crystal polyester, polyphthalamide, aromatic polyether ketone, syndiotactic polystyrene, aromatic polyimide, aromatic maleimide, aromatic bismaleimide, polyphenylene ether, styrene elastomer, etc. Aromatic polyamic acid is preferred, and aromatic polyimide or aromatic polyamic acid is more preferred.
The aromatic polyimide may be thermoplastic or non-thermoplastic. Thermoplastic polyimide means a polyimide that has undergone imidization and no further imidization reaction occurs.
Among these, non-thermoplastic polyimide is preferred as the AR polymer. If such a non-thermoplastic polyimide is used, island domains having the desired domain diameter are likely to be formed in the film. Therefore, this film can exhibit better UV processability.

In this specification, "non-thermoplastic polyimide" refers to a molded product (film, etc.) formed by combining monomers, drying a solution obtained by solution polymerization (solution of polyimide precursor), and further imidizing the solution. ) is defined as a polyimide that retains its shape when heated at 450°C for 1 minute. A polyimide that deforms or fuses due to wrinkles or elongation when the molded article is heated at 450° C. for 1 minute is referred to as a "thermoplastic polyimide."

Specific examples of thermoplastic polyimides include the "Neoprim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), the "Spixeria (registered trademark)" series (manufactured by Somar Corporation), and the "Q-PILON (registered trademark)" series (manufactured by Somar Corporation). ``WINGO'' series (manufactured by Wingo Technology), ``Thomide (registered trademark)'' series (manufactured by T&K TOKA), ``KPI-MX'' series (manufactured by Kawamura Sangyo), ``Yupia (manufactured by Kawamura Sangyo), (registered trademark)-AT” series (manufactured by Ube Industries, Ltd.).

Preferably, the non-thermoplastic polyimide includes non-thermoplastic block portions.
A non-thermoplastic block part means that when a polyimide precursor obtained by solution polymerizing only the monomers constituting the block part is evaluated using the same method as in the definition of non-thermoplastic polyimide described above, the shape is retained. refers to a block site formed from a combination of monomers to form a polyimide.

On the other hand, a thermoplastic block part is a polyimide precursor obtained by solution polymerizing only the monomers constituting the block part, and when evaluated using the same method as in the definition of non-thermoplastic polyimide described above, the shape is Refers to a blocking site formed from a combination of monomers that forms a non-retained polyimide.
Note that when determining whether a block portion is thermoplastic or non-thermoplastic, if a combination of rigid monomers is selected, the molded article may break or break into pieces. In this case, the pieces can be collected and heated, and the judgment can be made based on how well they retain their shape.

The glass transition temperature of the non-thermoplastic polyimide is preferably 280°C or higher, more preferably 290°C or higher. The glass transition temperature is preferably 450°C or lower, more preferably 400°C or lower. In this case, the film can be formed by melt extrusion molding at a lower temperature.
The imide group density of the non-thermoplastic polyimide is preferably 0.20 to 0.35. If the imide group density is below the above upper limit, the water absorption rate of the non-thermoplastic polyimide will be lower, making it easier to suppress changes in the electrical properties (particularly dielectric properties) of the film. When the imide group density is equal to or higher than the lower limit, the imide group functions as a polar group, and not only the adhesiveness of the film is further improved, but also the water absorption rate tends to be significantly lowered.

The imide group density is the value obtained by dividing the molecular weight per unit of the imide group portion (140.1) by the molecular weight per unit of the polyimide in a polyimide obtained by imidizing a polyimide precursor. For example, a polyimide precursor consisting of two components, 1 mole of pyromellitic dianhydride (molecular weight: 218.1) and 1 mole of 3,4'-oxydianiline (molecular weight: 200.2), was imidized. The imide group density of polyimide (molecular weight per unit: 382.2) is 0.37, which is the value obtained by dividing 140.1 by 382.2.

Non-thermoplastic polyimides include 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, paraphenylenediamine, 4,4'-bis(4-aminophenoxy)biphenyl, and 2,2'-dimethyl- 4,4'-diaminobiphenyl, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 4,4 '-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 2,2'-n-propyl-4,4'-diaminobiphenyl and 4-amino A plurality of aromatic diamines selected from the group consisting of phenyl-4'-aminobenzoate, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3, 3',4'-biphenyltetracarboxylic dianhydride, 2,3,2',3'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4, 4'-benzophenonetetracarboxylic dianhydride, 1,4-phenylenebis(trimellitic acid monoester) dianhydride, p-phenylenebis(tritate anhydride), 1,4-phenylenebis(trimellitic acid monoester) ) a plurality of aromas selected from the group consisting of dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, and 2,3,6,7-naphthalenetetracarboxylic dianhydride It is preferable to include a unit formed from a group acid dianhydride. In this case, the non-thermoplasticity of the non-thermoplastic polyimide is improved, and not only the adhesion of the film is further improved, but also the water absorption rate tends to decrease significantly.
The non-thermoplastic polyimide preferably contains 80 mol% or more of the above units based on all units. Its upper limit is 100 mol%.

Furthermore, non-thermoplastic polyimides include metaphenylene diamine, 1,5-diaminonaphthalene, benzidine, 3,3'-dimethoxybenzidine, paraxylylene diamine, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4 , 4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 1,4-bis(3-methyl-5-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4- Bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl) ) Other diamines such as benzidine and 2,2-bis(4-aminophenyl)hexafluoropropane may be used as monomer components of the unit. These other diamines may be used alone or in combination of two or more.

Furthermore, non-thermoplastic polyimides include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, pyridine-2,3,5,6-tetracarboxylic acid, 4,4'-oxydiphthalic acid, 3,3 ',4,4'-biphenyltetracarboxylic acid, 2,3',3,4'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 5,5'-[1- Other tetracarboxylic acids such as methyl-1,1-ethanediylbis(1,4-phenylene)bisoxy]bis(isobenzofuran-1,3-dione), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, etc. Alternatively, a derivative thereof may be used as a monomer component of the unit. These other tetracarboxylic acids or derivatives thereof may be used alone or in combination of two or more.

The synthesis of a polyimide precursor (polyamic acid) for producing a non-thermoplastic polyimide is preferably carried out in the presence of a solvent. Specific examples of the solvent include dimethyl sulfoxide, diethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N -vinyl-2-pyrrolidone, phenol, cresol, xylenol, halogenated phenol, catechol, hexamethylphosphoramide.
Preferably, the polyimide precursor is prepared in a solution containing the polyimide precursor as a solid content of 5 to 40% by weight. In this case, the viscosity of the solution is preferably 100 to 1000 Pa·s. Moreover, a part of the polyimide precursor may be imidized in the solution.

Styrene elastomers include styrene-butadiene copolymer, hydrogenated-styrene-butadiene copolymer, hydrogenated-styrene-isoprene copolymer, styrene-butadiene-styrene block copolymer, and styrene-isoprene-styrene block copolymer. Examples include hydrogenated products of a styrene-butadiene-styrene block copolymer, hydrogenated products of a styrene-isoprene-styrene block copolymer, and the like.
The D50 of the AR particles in the present invention is 1 to 10 μm, more preferably 2 to 7 μm. In this case, when forming a melt-kneaded product, mixing with the first F particles can be easily performed.
Examples of the aromatic polyetherketone include polyetherketone, polyetheretherketone, polyetherketoneketone, and polyetheretherketoneketone.

The definition and scope of the second F polymer in the present invention, including preferred embodiments, are the same as those of the first F polymer. Furthermore, the definition and range of the second F particles, including preferred aspects, are the same as those of the first F particles.
Note that, as described above, the second F polymer is preferably the same F polymer as the first F polymer.
Preferably, the second F particles are in the form of pellets.

The melt-kneaded product in this method is obtained by melt-kneading the first F particles and AR particles. The melt-kneaded product is obtained, for example, by charging the first F particles and AR particles into an extruder, and kneading the mixture of the first F particles and AR particles while melting them by heating in the extruder. . The first F particles and AR particles may be mixed in advance in a blender and then introduced into the extruder.
The melt-kneaded product is preferably in the form of pellets. In such a case, island domains having the desired domain diameter are likely to be formed in the film. Therefore, this film can exhibit better UV processability.

For melt extrusion molding in this method, it is preferable to use a die coating method (melt extrusion molding using a T-die). Specifically, the die coating method is performed as follows.
First, a melt-kneaded product of first F particles and AR particles and second F particles are introduced into an extruder connected to a T-die. Next, in an extruder, the mixture of the melt-kneaded product and the second F particles is kneaded while being melted by heating to obtain a melt-kneaded product.
Next, this melt-kneaded material is supplied into the T-die and discharged from the lip (discharge port) of the T-die. Thereafter, the discharged melt-kneaded material is cooled and formed into a film by contacting the first cooling roll disposed vertically below the T-die. Next, the melt-kneaded product formed into a film is conveyed while contacting another cooling roll and a conveyance roll arranged further downstream, and is finally wound up on a winding roll as the main film.

It is preferable that the melt-kneaded product of the first F particles and AR particles and the second F particles are mixed in advance in a blender and then introduced into an extruder.
The initial temperature of the cooling roll is preferably 150 to 250°C. In this case, since the melt-kneaded product can be rapidly cooled, small spherulites of the F polymer are likely to be formed in the film, and therefore, island domains having an appropriate domain diameter due to the AR polymer are also likely to be formed.
From the viewpoint of enhancing this quenching effect, an air knife may be provided immediately after the first cooling roll to blow a slit-shaped air stream from a slit nozzle onto the melt-kneaded material formed into a film.
In this case, the temperature of the air blown out from the air knife is preferably 150 to 200°C, more preferably 170 to 200°C. Further, the flow velocity of the air blown out from the air knife is preferably 10 to 20 m/sec.

Further, from the same viewpoint, a non-contact type heating section may be provided to maintain the temperature of the melt-kneaded material discharged from the T-die at a high level until it contacts the first cooling roll. The non-contact type heating section can be configured to include, for example, a pair of heaters arranged opposite to each other, and the melted and kneaded material can be passed between them.
In this case, when the temperature of the melt-kneaded material in the T-die is defined as A [°C] and the temperature of the non-contact heating section is defined as B [°C], the absolute value of the difference (|AB|) is 70 ℃ or less, more preferably 30 to 50°C. In this case, the temperature of the melt-kneaded product can be maintained sufficiently high until it reaches the first cooling roll while preventing the F polymer and the AR polymer from deteriorating in quality.

The resulting film includes a sea domain of F polymer (first F polymer and second F polymer) and an island domain of AR polymer, the content of the AR polymer is 10% by mass or less, and the island domain The average domain diameter of is 1 to 10 μm. When this film is formed to have a thickness of 25 μm, the transmittance of light having a wavelength of 355 nm in this 25 μm thick film is 80% or less.
The definition and scope of the F polymer in this film, including preferred embodiments, are the same as those of the first F polymer in this method. Further, the definition and scope of the AR polymer in this film, including preferred embodiments, are the same as those of the AR polymer in this method.
As described above, this film has high UV absorption because the content of the AR polymer includes at least island domains having an appropriate domain diameter.

The content of the AR polymer in this film is preferably 0.1 to 5% by mass, more preferably 0.3 to 4% by mass. In this case, the present film can be provided with sufficiently high UV absorption while preventing the properties based on the F polymer (electrical properties, etc.) from deteriorating.
Further, the average domain diameter of the island domains is preferably 3 to 7 μm. In this case, the UV absorption of the film is further improved because the light (UV) can penetrate more effectively into the film (island domain).

The transmittance of light having a wavelength of 355 nm (hereinafter also referred to as "light transmittance") in this film having a thickness of 25 μm is preferably 70% or less, more preferably 60% or less. The lower limit of light transmittance is 0%. In this case, it can be determined that the film has sufficiently high UV absorption.
Further, in the plane of the extruded film having a thickness of 25 μm, the difference between the maximum value and the minimum value of light transmittance is preferably 7% or less, more preferably 5% or less. In this case, it can be determined that the film has homogeneous characteristics. Note that the lower limit of the difference between the maximum value and the minimum value of light transmittance is usually 1% or more.

Preferably, the thickness of the film is more than twice the average domain diameter of the island domains, more preferably more than 4 times, even more preferably more than 6 times. The thickness of the film is preferably 15 times or less, more preferably 10 times or less, the average domain diameter of the island domains. In this case, the UV absorbability of the film can be further improved.
The specific thickness of this film is preferably 5 to 150 μm, more preferably 10 to 100 μm, and even more preferably 20 to 50 μm.

The film may contain other components besides the two F polymers and the AR polymer. In this method, other components may be mixed into the melt-kneaded product, the second F particles, or both the melt-kneaded product and the second F particles.
Other ingredients include inorganic fillers, organic fillers, resins other than the above polymers, thixotropic agents, antifoaming agents, silane coupling agents, dehydrating agents, plasticizers, weathering agents, antioxidants, and heat stabilizers. , a lubricant, an antistatic agent, a whitening agent, a coloring agent, a conductive agent, a mold release agent, a surface treatment agent, a viscosity modifier, a flame retardant, and the like.

The inorganic filler is preferably a nitride filler or an inorganic oxide filler, such as a boron nitride filler, beryllia filler (beryllium oxide filler), silicate filler (silica filler, wollastonite filler, talc filler), or metal. Oxide fillers (cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.) fillers are more preferred, and silica fillers are even more preferred.
The inorganic filler has at least a portion of its surface coated with a silane coupling agent (3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, -methacryloxypropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, 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 granular, acicular (fibrous), or plate-like. Specific shapes of the inorganic filler include spherical, scale-like, layered, leaf-like, almond-like, columnar, comb-like, equiaxed, leaf-like, mica-like, block-like, tabular, wedge-like, rosette-like, and mesh. Examples include prismatic and prismatic shapes.
One type of inorganic filler may be used alone, or two or more types may be used in combination.

Preferred specific examples of inorganic fillers include silica filler (such as the AdmaFine (registered trademark) series manufactured by Admatex Co., Ltd.), zinc oxide surface-treated with an ester such as propylene glycol dicaprate (Sakai Chemical Industry Co., Ltd.), etc. ``FINEX (registered trademark)'' series, manufactured by Denka Co., Ltd.), spherical fused silica (``SFP (registered trademark)'' series, manufactured by Denka Co., Ltd.), coated with polyhydric alcohol and inorganic substances (``Tipake'', manufactured by Ishihara Sangyo Co., Ltd.) (registered trademark) series, etc.), rutile-type titanium oxide surface-treated with alkylsilane (Tayka's "JMT (registered trademark)" series, etc.), hollow silica filler (Taiheiyo Cement Co., Ltd.'s "E-SPHERES" ” series, Nippon Steel Mining Co., Ltd.'s "Silinax" series, Emerson & Cuming's "Ecocos Fire" series, etc.), talc fillers (Nippon Talc Co., Ltd.'s "SG" series, etc.), steatite fillers (Nippon Talc Co., Ltd.'s "SG" series, etc.) Boron nitride fillers (Showa Denko's "UHP" series, Denka's "Denka Boron Nitride" series ("GP", "HGP" grades), etc.) .

Other resins include epoxy resins, acrylic resins, phenolic resins, polyolefin resins, modified polyphenylene ether resins, polyfunctional cyanate ester resins, polyfunctional maleimide-cyanate ester resins, polyfunctional maleimide resins, vinyl ester resins, and urea resins. resins, diallyl phthalate resins, melanin resins, guanamine resins, melamine-urea cocondensation resins, polycarbonate resins, polyarylate resins, polysulfones, and polyallylsulfones.

A metal-clad laminate having a polymer layer and a metal foil layer can be manufactured by heat-pressing the film and the metal foil.
The metal clad laminate may include layers other than the polymer layer and the metal foil layer. Other layers include a heat-resistant resin layer.
Specific examples of the layer structure of such a metal-clad laminate include metal foil layer/polymer layer/heat-resistant resin layer, metal foil layer/polymer layer/heat-resistant resin layer/polymer layer/metal foil layer, metal foil layer/heat-resistant resin layer Examples include heat-resistant resin layer/polymer layer/heat-resistant resin layer/metal foil layer.
As the metal foil, copper foil is preferable. Examples of the copper foil include rolled copper foil and electrolytic copper foil. The copper foil may be provided with a rust preventive layer such as zinc chromate or a barrier layer such as nickel or cobalt. Further, the barrier layer may be formed by plating treatment or by chemical conversion treatment.

From the viewpoint of improving the adhesion between the metal foil layer and the polymer layer, the surface of the metal foil layer may be treated with a silane coupling agent. Examples of the silane coupling agent include epoxysilane, aminosilane, vinylsilane, acryloxysilane, methacryloxysilane, ureidosilane, mercaptosilane, sulfidesilane, and isocyanatesilane, with acryloxysilane, methacryloxysilane, and epoxysilane being preferred. One type of silane coupling agent may be used, or two or more types may be used in combination.
Rzjis of the surface of the metal foil layer on the polymer layer side is preferably 0.3 to 1.6. When Rzjis is 0.3 or more, delamination is less likely to occur between the metal foil layer and the polymer layer during hole-drilling using a UV-YAG laser. If Rzjis is 1.6 or less, increase in transmission loss due to roughness can be suppressed.
The thickness of the metal foil layer is preferably 3 to 18 μm, more preferably 6 to 12 μm.

The dielectric loss tangent of the polymer layer is preferably 0.0005 to 0.0040, more preferably 0.0007 to 0.0030. The lower the dielectric loss tangent, the better the electrical properties of the polymer layer.
The thickness of the polymer layer is preferably 1 to 50 μm, more preferably 2 to 25 μm. If the thickness of the polymer layer is at least the above lower limit, it is easy to obtain a printed wiring board with low transmission loss. If the thickness of the polymer layer is below the above upper limit, UV processability will be further improved. In addition, when a metal clad laminate has a plurality of polymer layers, it is preferable that the thickness of each polymer layer is within the above range.

Examples of the constituent material (heat-resistant resin material) of the heat-resistant resin layer include polyimide, liquid crystal polymer, polyether ether ketone, polyphenylene oxide, polyester, polyamide, and aramid fiber. Among these, the heat-resistant resin material is preferably at least one selected from the group consisting of polyimide, liquid crystal polymer, polyether ether ketone, polyphenylene oxide, and aramid fiber, and polyimide or liquid crystal polymer is more preferable.
From the viewpoint of improving UV processability, the heat-resistant resin layer preferably contains fewer different materials, and is preferably composed of the above-mentioned non-thermoplastic polyimide alone.
When the metal clad laminate has a heat-resistant resin layer, the ratio of the thickness of the polymer layer (total thickness in the case of plurality) to the thickness of the heat-resistant resin layer (total thickness in the case of plurality) is 0. 5 to 2 is preferred. In this case, it becomes easy to make holes in the polymer layer using a UV-YAG laser, and transmission loss is also easily reduced.

The thickness of the metal-clad laminate is preferably 10 to 150 μm, more preferably 15 to 100 μm, and even more preferably 20 to 50 μm. In this case, the metal-clad laminate can be used more stably as a printed wiring board, and through holes can be easily formed using a UV-YAG laser.
The opening shape of the through hole is preferably circular. In this case, the diameter can be set within the range of 0.05 to 0.10 mm.
The number of through holes may be one or two or more.
A plating layer may be formed on the inner wall surface of the through hole, if necessary. For example, when a printed wiring board has conductors on both sides in the thickness direction, conduction between the conductors can be ensured by forming a plating layer on the inner wall surface of the through hole.

Examples of the plating layer include a copper plating layer, a gold plating layer, a nickel plating layer, a chrome plating layer, a zinc plating layer, and a tin plating layer.
Transmission loss is a parameter representing the attenuation of a signal from a signal input section to an output section in a printed wiring board.
The transmission loss of the printed wiring board is preferably -0.07 dB/mm or more, more preferably -0.06 dB/mm or more at 40 GHz.

The printed wiring board can be manufactured by a method of forming through holes in the metal clad laminate by irradiating the metal clad laminate with a UV-YAG laser.
The wavelength of the UV-YAG laser is preferably 3rd harmonic (wavelength 355 nm) or 4th harmonic (266 nm).
A UV-YAG laser processing machine can be used for drilling. Trepanning processing can be used for hole-drilling processing using UV-YAG laser. Specifically, the metal clad laminate can be partially hollowed out by irradiating a laser with a narrowed diameter while circulating along the periphery of the location where the through hole is to be formed, thereby forming the through hole.

The laser output, the number of rounds of laser irradiation, and the laser oscillation frequency can be set depending on the thickness of the metal clad laminate.
When using a laser beam with a wavelength of 355 nm, its output is preferably 0.1 to 3.0 W, more preferably 0.5 to 2.0 W. When using a laser beam with a wavelength of 266 nm, its output is preferably 0.01 to 0.5W, more preferably 0.05 to 0.3W. In this case, the through-holes can be easily formed, and the amount of resin scattered due to laser heat can be reduced.
The number of rounds of laser irradiation is preferably 5 to 50 times.
When using a laser beam with a wavelength of 355 nm, its oscillation frequency is preferably 20 to 80 kHz. When using a laser beam with a wavelength of 266 nm, its oscillation frequency is preferably 1 to 10 kHz.

The metal-clad laminate has a polymer layer made of this film having a predetermined sea-island structure, and the transmittance of light having a wavelength of 355 nm is controlled. Therefore, the absorption rate of the UV-YAG laser increases even without the use of additives, and as a result, it is possible to easily penetrate small diameters using the UV-YAG laser while suppressing the deterioration of electrical properties. Pores can be formed.
The printed wiring board manufactured in this way can be suitably used for high frequency applications.

Although the method for producing an extruded film and the extruded film of the present invention have been described above, the present invention is not limited to the configuration of the embodiments described above.
For example, the method for producing an extruded film of the present invention may additionally include any other process in the configuration of the above embodiment, or may be replaced with any process that produces the same effect.
Furthermore, the extruded film of the present invention may additionally have any other configuration in the configuration of the above embodiment, or may be replaced with any configuration that produces the same effect.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.
1. Preparation of each component [F particles]
F particle 1: F polymer 1 containing TFE units, NAH units, and PPVE units in this order at 97.9 mol%, 0.1 mol%, and 2.0 mol%, and having a polar functional group (melting temperature: 300 ° C. Powder-like particles (D50: 2.1 μm) consisting of MFR: 28 g/10 min)
F particle 2: F polymer 2 containing TFE units, NAH units, and PPVE units in this order at 97.9 mol%, 0.1 mol%, and 2.0 mol%, and having a polar functional group (melting temperature: 300 ° C. MFR: 22g/10min) F particles 3: Contains 97.5 mol% and 2.5 mol% of TFE units and PPVE units in this order, and has no polar functional groups F polymer 3 (melting temperature Powder-like particles (D50: 2.3 μm) consisting of 305° C., MFR: 28 g/10 min)
F particles 4: Pellets made of F polymer 4 (melting temperature 305°C, MFR: 22 g/10 min) containing 97.5 mol% and 2.5 mol% of TFE units and PPVE units in this order and having no polar functional groups. F particles 5: F polymer 5 containing 97.5 mol% and 2.5 mol% of TFE units and PPVE units in this order and having no polar functional group (melting temperature 305°C, MFR: 16 g/10 min) pellet-like particles consisting of

[AR particles]
AR particle 1: non-thermoplastic polyimide (Tg: 337°C) particle (D50: 3 μm, “P84NT superfine” manufactured by Daicel-Evonik)
AR particle 2: non-thermoplastic polyimide (Tg: 355°C) particle (D50: 13 μm, “UIP-SA” manufactured by Ube Industries, Ltd.)
[Copper foil]
Copper foil 1: Low roughening copper foil (thickness: 12 μm, manufactured by Fukuda Metal Foil and Powder Industries Co., Ltd., "CF-T49A-DS-HD2")

2. Film manufacturing example [Example 1]
F particles 1 (90 parts by mass) and AR particles (10 parts by mass) were stirred in a blender to prepare a mixture. The mixture was melt-kneaded (screw rotation speed: 200 rpm, set resin temperature: 370° C.) using a twin-screw extruder (manufactured by Technovel, “KZW15TW-45MG”) to produce pellets 1. The MFR of pellet 1 was 24 g/10 min.
Pellets 1 (10 parts by mass) and F particles 2 (90 parts by mass) were stirred in a blender to prepare a mixture. The mixture was extruded using a single screw extruder (a 30 mmφ single screw extruder with a 700 mm width coat hanger die) at a die temperature of 340° C. to obtain a film 1 having a width of 500 mm, a length of 100 m, and a thickness of 25 μm. The average domain diameter of the island domains in Film 1 was 3 μm.
Note that the average domain diameter is determined by determining island domains through image processing from a SEM photograph of a cross section of the film observed using a scanning electron microscope (SEM).

[Examples 2 to 6]
Pellets 2 to 5 were obtained in the same manner as pellet 1, except that the types and amounts of F particles and AR particles were changed as shown in Table 1.
Films 2 to 6 were obtained in the same manner as Film 1, except that the types and amounts of pellets and F particles were changed as shown in Table 2.
[Example 7]
F particles 2 (99 parts by mass) and AR particles 1 (1 part by mass) were stirred in a blender to prepare a mixture. The mixture was extruded using a single screw extruder (a 30 mmφ single screw extruder with a 750 mm width coat hanger die) at a die temperature of 340° C. to obtain a film 7 with a width of 500 mm, a length of 100 m, and a thickness of 25 μm. .

The components of Films 1 to 7, the difference in MFR between each pellet and F particles, the content of AR polymer in the film, and the average domain diameter of the island domains are also shown in Table 2. Note that there is no island domain in film 6, and film 7 did not use pellets, so there is no difference in MFR between pellets and F particles.

3. Manufacture of laminate The copper foil 1 was layered on the surface of the film 1, and the laminate 1 was obtained by vacuum hot pressing. Note that the processing conditions were: temperature: 340°C, pressurizing pressure: 3.0 MPa, and pressurizing time: 20 minutes.
Laminates 2 to 7 were obtained in the same manner as laminate 1 except that Film 1 was changed to Films 2 to 6.

4. Evaluation 4-1. Film evaluation 4-1-1. Evaluation of light transmittance The transmittance of the obtained film to ultraviolet light at a wavelength of 355 nm was measured using a spectrophotometer (manufactured by Shimadzu Corporation, "UV-3600"). Further, the transmittance of the ultraviolet rays was measured at 60 points in total, 3 points in the width direction of the film and every 5 m in the longitudinal direction, and the difference between the maximum value and the minimum value was determined.

4-1-2. Evaluation of Electrical Properties The dielectric loss tangent (measurement frequency: 10 GHz) of the obtained film was measured using the SPDR (split post dielectric resonance) method.
[Evaluation criteria]
○: Dielectric loss tangent is less than 0.0010.
Δ: Dielectric loss tangent is 0.0010 or more and 0.0040 or less.
×: Dielectric loss tangent is over 0.0040.

4-2. Evaluation of laminate 4-2-1. Evaluation of UV processability (UV laser processability) Using a laser processing machine (esi5330), the laminate was irradiated with a UV-YAG laser with a wavelength of 355 nm so as to orbit around a circle with a diameter of 100 μm. . Thereby, a circular through hole was formed in the laminate. Note that the laser output was 1.5 W, the laser focal diameter was 25 μm, the number of turns on the circumference was 16, and the oscillation frequency was 40 kHz.
Thereafter, pieces of the laminate containing through holes were cut out and hardened with thermosetting epoxy resin. Next, polishing was performed until the cross section of the through hole was exposed. The peripheral cross sections of 100 through-holes were observed with a microscope to confirm the occurrence of scraping and peeling at the layer interfaces, and evaluation was made based on the following criteria.
[Evaluation criteria]
〇: No scraping and peeling occurred in all through holes △: Scraping and peeling occurred in 1 to 5 through holes ×: Scraping and peeling occurred in more than 5 through holes The evaluation results are summarized in Table 3.

Claims (7)

A melt-kneaded product of particles of a first tetrafluoroethylene polymer having a melting temperature of 270 to 320°C and particles of an aromatic polymer having an average particle diameter of 1 to 10 μm, and a second polymer having a melting temperature of 270 to 320°C. A method for producing an extruded film, comprising melt-extruding a mixture with particles of a tetrafluoroethylene polymer to obtain an extruded film containing 10% by mass or less of the aromatic polymer ,
A method for producing an extrusion film, wherein the melt flow rate of the second tetrafluoroethylene polymer is within the range of ±8 g/10 minutes of the melt flow rate of the melt-kneaded product . The first tetrafluoroethylene polymer and the second tetrafluoroethylene polymer each independently contain a unit based on perfluoro(alkyl vinyl ether) and have a polar functional group, or a tetrafluoroethylene polymer having a polar functional group; The production method according to claim 1, which is a tetrafluoroethylene polymer containing 2.0 to 5.0 mol% of units based on perfluoro(alkyl vinyl ether) based on the units and having no polar functional group. The manufacturing method according to claim 1 or 2 , wherein the aromatic polymer is a non-thermoplastic polyimide. The manufacturing method according to any one of claims 1 to 3 , wherein the glass transition temperature of the aromatic polymer is in the range of the melting temperature of the first tetrafluoroethylene polymer +20°C or higher. The manufacturing method according to any one of claims 1 to 4 , wherein the melt flow rate of the second tetrafluoroethylene polymer is in the range of ±7 g/10 minutes of the melt flow rate of the melt-kneaded product. According to any one of claims 1 to 5 , the content of the aromatic polymer in the melt-kneaded product is 5 to 30 parts by mass based on 100 parts by mass of the first tetrafluoroethylene polymer. Manufacturing method described. The manufacturing method according to any one of claims 1 to 6 , wherein in the mixture, a mixing ratio of the particles of the second tetrafluoroethylene polymer to the melt-kneaded material in terms of mass is 5 to 20. .