TW202221073A - Method for manufacturing multilayer film, and multilayer film - Google Patents

Abstract

To provide: a multilayer film that has excellent adhesion and includes a polymer layer for which the ratio of the thickness of an end relative to the thickness of the center is adjusted to a prescribed range; and a method for manufacturing the same. A multilayer film according to the present invention comprises: a polymer film having a surface that has been treated to enhance the surface tension of the polymer film; and a polymer layer which is formed on the surface of the polymer film and contains a tetrafluoroethylene polymer. The ratio of the thickness of an end of the polymer layer relative to the thickness of the center of the polymer layer is 1.1 or lower. The method for manufacturing the multilayer film is characterized by: coating a surface of a polymer film, that has been treated to enhance surface tension, with a liquid composition containing tetrafluoroethylene polymer powder and a liquid dispersion medium having a surface tension of at least 30 mN/m, the content of the powder being at least 10% by mass; and then heating the coating, to obtain a multilayer film on which a polymer layer is formed on the surface of the polymer film.

Description

Manufacturing method of laminated film and laminated film

The present invention relates to a method for producing a laminated film, wherein the laminated film is provided with a polymer layer on the surface of a polymer film subjected to a treatment to increase the surface tension, and the above-mentioned polymer layer is obtained by using a compound having a specific surface tension. The liquid composition of the liquid dispersion medium is formed, and the increase in the thickness of the end portion is reduced; and the present invention relates to a laminated film having a ratio of the thickness of the end portion to the thickness of the central portion adjusted to a specific value range of polymer layers.

For the printed circuit board used for transmitting high frequency signals, it is required to have excellent transmission characteristics. As an insulating layer material of a printed circuit board with high transmission properties, tetrafluoroethylene-based polymers with low relative permittivity and low dielectric dissipation factor have been attracting attention. As a material for forming an insulating layer containing such a polymer, a liquid composition containing a powder of a tetrafluoroethylene-based polymer and a liquid dispersion medium is known. Patent Documents 1 and 2 describe a laminate film formed by applying such a liquid composition to the surface of a polyimide film, heating it, and having tetrafluoroethylene on both sides of the polyimide film. Vinyl polymer layer. prior art literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 9-157418 Patent Document 2: Japanese Patent Laid-Open No. 2005-35300

[Problems to be Solved by Invention]

On the other hand, since the tetrafluoroethylene-based polymer is non-adhesive, the adhesion between the polyimide film and the tetrafluoroethylene-based polymer layer in such a laminate film is generally low. Therefore, the present inventors attempted to improve the adhesiveness of the laminated film by surface treatment of the polyimide film. However, in this case, the inventors of the present invention newly discovered a problem that the thickness of the laminated film tends to be uneven, and in particular, that the edge of the laminated film is prone to bulge. Therefore, the inventors of the present invention have also newly discovered the following problem: when the elongated body of such a laminated film is wound into a roll shape, the laminated film will be wrinkled or stretched, resulting in a decrease in yield when used as a printed circuit board material or the like. Difference.

As a result of intensive research conducted by the present inventors, it was found that a liquid composition comprising a liquid dispersion medium having a surface tension in a specific range also has excellent dispersion stability and is more uniform on the surface of a polymer film subjected to a treatment to increase the surface tension. It can form a laminated film with less uneven thickness and high adhesion strength. The present invention has been accomplished based on such findings, and an object of the present invention is to provide a laminated film having a polymer layer having excellent adhesiveness and a difference between the thickness of the end portion and the thickness of the central portion, and a method for producing the same. The ratio is adjusted to a specific range. [Technical means to solve problems]

The present invention has the following aspects. <1> A method for producing a laminated film, comprising coating a liquid composition on the surface of a polymer film subjected to a treatment for increasing surface tension, and heating to obtain a polymer film having a polymer layer formed on the surface of the polymer film. In the laminated film, the liquid composition contains a powder of a tetrafluoroethylene-based polymer and a liquid dispersion medium having a surface tension of 30 mN/m or more, and the content of the powder is 10 mass % or more. <2> The production method according to <1>, wherein the treatment is at least one type of hydrophilization treatment selected from the group consisting of corona treatment and plasma treatment. <3> The production method according to <1> or <2>, wherein the surface tension of the surface of the polymer film subjected to the above treatment is greater than the surface tension of the liquid dispersion medium. <4> The production method according to any one of <1> to <3>, wherein the arithmetic mean roughness Ra of the surface of the polymer film is 0.01 to 5 μm. <5> The production method according to any one of <1> to <4>, wherein a polar functional group is present on the surface of the polymer film subjected to the above treatment. <6> The production method according to any one of <1> to <5>, wherein the average particle diameter of the powder is 0.1 to 10 μm. <7> The production method according to any one of <1> to <6>, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a melting temperature of 260 to 320°C. <8> The production method according to any one of <1> to <7>, wherein the tetrafluoroethylene-based polymer contains units based on perfluoro(alkyl vinyl ether), and contains 1.5 to 1.5 to 5.0 mol% of tetrafluoroethylene-based polymer based on perfluoro(alkyl vinyl ether) units. <9> The production method according to any one of <1> to <8>, wherein the liquid composition contains an aromatic polymer. <10> The production method according to any one of <1> to <9>, wherein the polymer film contains an aromatic polyimide. <11> The production method according to any one of <1> to <10>, wherein the average thickness of the polymer film is 10 μm or more, and the average thickness of the polymer layer is 10 μm or more. <12> A laminated film comprising: a polymer film having a surface treated to increase surface tension; and a polymer layer formed on the surface and containing a tetrafluoroethylene-based polymer, and the polymer layer The ratio of the thickness of the end portion to the thickness of the central portion is 1.1 or less. <13> The laminated film according to <12>, wherein the above-mentioned laminated film is pre-dried at 50° C. for 48 hours, and then immersed in pure water at 23° C. for 24 hours, and the above-mentioned values before and after immersion in the above-mentioned pure water are measured. In the case of the mass of the laminated film, the water absorption rate calculated based on the following formula is 0.1% or less. Water absorption rate (%) = (mass after pure water immersion - mass after pre-drying) / mass after pre-drying × 100 <14> The laminated film according to <12> or <13>, wherein the average thickness of the polymer film is 10 μm or more, and the average thickness of the polymer layer is 10 μm or more. <15> The laminate film according to any one of <12> to <14>, wherein the polymer film is provided on both surfaces of the polymer film. [Effect of invention]

ADVANTAGE OF THE INVENTION According to this invention, the laminated film provided with the polymer layer is excellent in adhesiveness, and the ratio of the thickness of an edge part with respect to the thickness of a center part is adjusted to a specific range.

The following terms have the following meanings. "Average particle size (D50)" is the volume-based cumulative 50% particle size of the object (powder or inorganic filler) determined by the laser diffraction scattering method. That is, the average particle diameter (D50) is obtained by measuring the particle size distribution of the object by the laser diffraction scattering method, and taking the total volume of the aggregate of the particles of the object as 100% to obtain a cumulative curve, and on the cumulative curve The particle size at the point where the cumulative volume becomes 50%. "D90" is the volume-based cumulative 90% particle size of the object measured in the same manner. The "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 obtained by analyzing and measuring the polymer by dynamic viscoelasticity measurement (DMA). The "specific surface area" is a value obtained when the powder is measured by the gas adsorption (constant volume method) BET multipoint method using NOVA4200e (manufactured by Quantachrome Instruments). "Viscosity" is a value obtained by measuring the liquid composition at 25°C under the condition of a rotational speed of 30 rpm using a Brookfield viscometer. The measurement was repeated three times, and the average value of the three measurements was taken. The "thixotropy ratio" means that the viscosity η ₁ is obtained by measuring the liquid composition at a rotational speed of 30 rpm, and the viscosity η ₂ is obtained by measuring at _a rotational speed of 60 rpm. The value calculated by dividing by the viscosity η ₂ (η ₁ /η ₂ ). "Yield strength" means that when the strain becomes large, the relationship between the strain and the stress is not proportional to the stress that begins to generate the phenomenon that the strain remains even after the stress is removed, and is defined as "the tensile modulus of elasticity of the film measured according to ASTM D882" Stress at 5% strain" is specified. "Refractory plastic deformation" means the property of increasing the stress when the support layer is plastically deformed, or the property of requiring a large stress when plastically deforming, and is defined as "15" when the tensile modulus of elasticity of the film is measured according to ASTM D882. % strain stress". The "tensile elastic modulus" is a value when the film is measured at a measurement frequency of 10 Hz using a wide-area viscoelasticity measuring device. "Average thickness" is the average value of the measured values obtained by measuring the thickness of the film at 10 locations with a contact thickness gauge DG-525H (manufactured by Ono Shoki Co., Ltd.) using a measuring head AA-026 (ϕ10 mm, SR7). "The ten-point average roughness (Rzjis) of the surface of metal foil (metal substrate)" is the value specified in Annex JA of JIS B 0601:2013 (ISO 4287:1997, Amd.1:2009). "Arithmetic mean roughness Ra" is the value of the surface of the film measured according to JIS B 0601:2013 (ISO 4287:1997, Amd.1:2009). The "unit" in the polymer may be an atomic group directly formed from a monomer, or an atomic group obtained by processing the obtained polymer by a specific method, so that a part of the structure is converted. The unit based on the monomer A contained in the polymer is also simply referred to as "monomer A unit".

In the production method of the present invention (hereinafter, also referred to as "this method"), a liquid composition is applied to the surface of a polymer film subjected to a treatment for increasing the surface tension, followed by heating to obtain a polymer film with a A method for a laminated film of a polymer layer, wherein the liquid composition contains a powder of a tetrafluoroethylene-based polymer (hereinafter, also referred to as "F polymer") and a liquid dispersion medium having a surface tension of 30 mN/m or more, In addition, the content of the powder of the F polymer (hereinafter, also referred to as "F powder") is 10% by mass or more. Therefore, the obtained laminate film has a laminate of a polymer film and a polymer layer, the polymer film has a surface treated to increase the surface tension, and the polymer layer is formed on the surface and contains the F polymer. In such a laminated film, the ratio of the thickness of the edge part of a polymer layer with respect to the thickness of the center part exists in a specific range (preferably 1.1 or less). That is, the unevenness of the thickness of the polymer layer is reduced. The reason for this is not necessarily clear, but is considered as follows.

In this method, in order to improve the adhesiveness between the polymer film and the polymer layer, before coating the liquid composition, the surface of the polymer film is treated to increase the surface tension. However, when a liquid composition containing F powder is applied to the surface of the polymer film subjected to such a treatment, when the liquid composition flows from the central portion to the end portion and wets and spreads, the flow may occur at the end portion. A phenomenon that stops nearby (pinning phenomenon), causing the coating film to bulge. When the coating film (liquid composition) is heated in this state, the shape of the end portion is maintained, and the thickness of the end portion of the obtained polymer layer is larger than the thickness of the central portion. Therefore, in this method, a liquid composition containing a liquid dispersion medium having a surface tension of 30 mN/m or more is used. From this, it is considered that the wettability of the liquid composition to the surface of the polymer film is improved, and the uniform wetting spreads to the end of the polymer film, thereby reducing the unevenness of the thickness of the obtained polymer layer.

The F polymers in this process are polymers comprising tetrafluoroethylene (TFE) based units (TFE units). The F polymer is preferably thermally fusible, and its melting temperature is preferably 260 to 320°C, more preferably 285 to 320°C. When such an F polymer is used, it becomes easy to form the polymer layer which is dense and excellent in adhesiveness, and it becomes easy to obtain the laminated film which is excellent in heat resistance. The glass transition point (Tg) of the F polymer is preferably 75 to 125°C, more preferably 80 to 100°C. The melt viscosity of the F polymer at 380° C. is preferably 1×10 ² to 1×10 ⁶ Pa·s, more preferably 1×10 ³ to 1×10 ⁶ Pa·s.

The surface tension of the F polymer is preferably 16-26 mN/m, more preferably 16-20 mN/m. In addition, the surface tension of the F polymer can be measured by placing a droplet of the mixed solution (manufactured by Wako Pure Chemical Industries, Ltd.) for a wetting tension test specified in JIS K 6768 on a flat plate made of the F polymer. The fluorine content of the F polymer is preferably 70% by mass or more, more preferably 72 to 76% by mass. Although the F polymer with low surface tension and high fluorine content is excellent in electrical properties and other physical properties, on the other hand, the dispersion stability in the liquid composition is obviously low, and the liquid composition in this method is obtained by Using the above-mentioned liquid dispersion medium, the dispersion stability of the F polymer is improved.

As the F polymer, polytetrafluoroethylene (PTFE), a polymer containing a TFE unit and an ethylene-based unit, a polymer containing a TFE unit and a propylene-based unit, a TFE unit and a perfluoro(alkane-based) polymer may be exemplified. Polyvinyl ether) (PAVE) units (PAVE units) polymers (PFA), polymers comprising TFE units and hexafluoropropylene-based units (FEP), TFE units and fluoroalkylethylene-based units The polymer, the polymer comprising TFE units and chlorotrifluoroethylene-based units, is preferably PFA or FEP, more preferably PFA. The abovementioned polymers may further comprise units based on other comonomers. As PAVE, CF ₂ =CFOCF ₃ , CF ₂ =CFOCF ₂ CF ₃ , or CF ₂ =CFOCF ₂ CF ₂ CF ₃ (hereinafter, also referred to as "PPVE") is preferable, and PPVE is more preferable.

The F polymer preferably has polar functional groups. In this case, it is easy to make the polymer layer excellent in physical properties such as electrical properties and surface smoothness. The polar functional group may be included in the unit contained in the F polymer, or may be included in the terminal group of the F polymer main chain. Examples of the latter F polymer include polymers having polar functional groups as terminal groups derived from polymerization initiators, chain transfer agents, etc.; or polymers having polar functional groups prepared by plasma treatment or ionizing radiation treatment. base polymer.

The polar functional group is preferably a hydroxyl group-containing group, a carbonyl group-containing group, and a phosphonium group-containing group, more preferably a hydroxyl group-containing group and a carbonyl group-containing group, and still more preferably a carbonyl group-containing group. The hydroxyl group-containing group is preferably an alcoholic hydroxyl group-containing group, more preferably -CF ₂ CH ₂ OH, -C(CF ₃ ) ₂ OH and 1,2-diol group (-CH(OH)CH ₂ OH). The carbonyl group-containing group is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a urethane group (-OC(O)NH ₂ ), an acid anhydride residue (-C(O) OC(O)-), imide residues (-C(O)NHC(O)- etc.) and carbonate groups (-OC(O)O-), more preferably acid anhydride residues.

When the F polymer has polar functional groups, the number of polar functional groups in the F polymer is preferably 10 to 5000, more preferably 100 per 1×10 ⁶ carbon number of the main chain ~3000. Furthermore, the number of polar functional groups in the F polymer can be quantified by the composition of the polymer or the method described in International Publication No. 2020/145133.

The F polymer is preferably a tetrafluoroethylene-based polymer containing PAVE units and containing 1.5 to 5.0 mol% of PAVE units with respect to all units, more preferably a polymer containing PAVE units and having a polar functional group (1 ); or a polymer (2) comprising PAVE units and 2.0 to 5.0 mol % of PAVE units relative to all monomer units and having no polar functional groups. These polymers form microspheres in the polymer layer, so the physical properties of the obtained polymer layer are easily improved.

The polymer (1) preferably contains 90 to 98 mol % of TFE units, 1.5 to 9.97 mol % of PAVE units, and 0.01 to 3 mol % based on monomers having polar functional groups with respect to all units. unit. Moreover, as a monomer which has a polar functional group, itaconic acid anhydride, citraconic acid anhydride, and 5-norene-2,3-dicarboxylic acid anhydride (hereinafter, also referred to as "NAH") are preferable. As a specific example of the polymer (1), the polymer described in International Publication No. 2018/16644 can be mentioned.

The polymer (2) is preferably composed of only 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 with respect to all the units. The content of the PAVE units in the polymer (2) is preferably 2.1 mol % or more, more preferably 2.2 mol % or more, based on all the units. Furthermore, that the polymer (2) does not have polar functional groups means that the number of polar functional groups contained in the polymer is less than 500 per 1×10 ⁶ carbon atoms constituting the main chain of the polymer. The number of the above-mentioned polar functional groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of the above-mentioned polar functional groups is usually zero.

The polymer (2) can be produced by using a polymerization initiator or a chain transfer agent that does not generate polar functional groups as the end groups of the polymer chain, and can also be used for polymers with polar functional groups (at the end groups of the polymer chain). A polymer having a polar functional group derived from a polymerization initiator, etc.) is produced by fluorination treatment. As a method of the fluorination treatment, a method using a fluorine gas can be mentioned (refer to Japanese Patent Laid-Open No. 2019-194314, etc.).

The F powder in this method is a powder containing the F polymer, and the content of the F polymer is preferably 80% by mass or more, more preferably 100% by mass. The F powder may also contain other polymers than the F polymer. As another polymer, aromatic polyester, polyimide imide, polyimide, polypheylene ether, polyphenylene oxide, maleimide may, for example, be mentioned. .

The F powder may also contain inorganic substances. The inorganic substances are preferably oxides, nitrides, simple metals, alloys and carbon, more preferably silicon oxides, metal oxides (beryllium oxide, cerium oxide, aluminum oxide, alkali aluminum oxide, magnesium oxide, zinc oxide) , titanium oxide, etc.), boron nitride and magnesium metasilicate (mass talc), more preferably silicon dioxide and boron nitride, especially silicon dioxide. In this case, the dispersion stability of the F powder in the liquid composition is easily improved. It is preferable that the F powder containing inorganic substances has the F polymer as a core, and the surface of the core has inorganic substances. Such an F powder is obtained, for example, by combining (collision, agglomeration, etc.) a powder of an F polymer with a powder of an inorganic substance.

D50 of the F powder is preferably 10 μm or less, more preferably 8 μm or less, and still more preferably 5 μm or less. D50 of the F powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and still more preferably 1 μm or more. Moreover, as for D90 of F powder, it is preferable that it is less than 100 micrometers, and it is more preferable that it is 90 micrometers or less. The specific surface area of the F powder is preferably 1 to 8 m ² /g, more preferably 1 to 5 m ² /g, and still more preferably 1 to 3 m ² /g. When the D50, D90 and specific surface area of the F powder are within the above-mentioned ranges, the dispersion stability of the F powder in the liquid composition can be easily made excellent. Moreover, since the obtained polymer layer becomes dense, water resistance is easy to improve (water absorption rate is reduced).

One type of F powder may be used, or two or more types may be used. In the case of using two types of F powders, the F powder is preferably a powder of a thermally fusible F polymer (a powder of a thermally fusible F polymer containing a TFE unit and a PAVE unit and having a carbonyl group-containing group, etc.) and a non-thermally fusible one. Powder of F polymer (non-thermofusible PTFE powder, etc.). In addition, the ratio of the former powder to the total amount of the two types of F powders is preferably 50% by mass or less, more preferably 25% by mass or less. Moreover, the said ratio becomes like this. Preferably it is 0.1 mass % or more, More preferably, it is 1 mass % or more. Moreover, it is preferable that the D50 of the former powder is 1-4 micrometers, and the D50 of the latter powder is 0.1-1 micrometer.

The surface tension of the liquid dispersion medium in this method is 30 mN/m or more, preferably 35 mN/m or more, more preferably 40 mN/m or more. The surface tension is preferably 75 mN/m or less, more preferably 55 mN/m or less. When a liquid dispersion medium having such a surface tension is used, it is easy to obtain a liquid composition which is excellent in dispersion stability of the F powder and uniformly wets and spreads on the surface of the polymer film subjected to the above treatment. Specific examples of the liquid dispersion medium include N-methyl-2-pyrrolidone (NMP: 41), cyclohexanone (CHN: 35.2), dimethylsulfoxide (DMSO: 43.5), Ethylene glycol (DEG: 45.2), bromobenzene (35.75), water (72.8). In addition, the numerical value in parentheses is the surface tension (unit: mN/m) of each liquid dispersion medium. The liquid dispersion medium may be used alone or in combination of two or more.

Content of the F powder in a liquid composition is 10 mass % or more, Preferably it is 15 mass % or more, More preferably, it is 20 mass % or more. The content of the F powder is preferably 60% by mass or less, more preferably 40% by mass or less. According to the present invention, even if a liquid composition with a relatively high content of F powder is used, a polymer layer with less uneven thickness can be formed, so that a polymer layer of any thickness, especially a thicker polymer can be easily formed Floor. The content of the liquid dispersion medium in the liquid composition is preferably 40% by mass or more, more preferably 50% by mass or more. The content of the liquid dispersion medium is preferably 80% by mass or less.

The liquid composition in this method preferably contains an aromatic polymer (hereinafter, referred to as "AR polymer"). In this case, physical properties (electrical properties, adhesion, low water absorption, etc.) based on the F polymer, and physical properties (low linear expansion, UV absorption, etc.) based on the AR polymer can be imparted to the obtained polymer layer. ). The AR polymer can be dissolved or dispersed in a liquid dispersion medium. The glass transition point of the AR polymer is preferably 300-350°C, more preferably 315-335°C. In this case, the linear expansion coefficient of the polymer layer (laminated film) is easily lowered, and deformation caused by heating can be prevented or suppressed. The 5% weight loss temperature of the AR polymer is preferably 260°C or higher, more preferably 300°C or higher, and still more preferably 320°C or higher. The 5% weight loss temperature of the AR polymer is preferably 600°C or lower. Within the above range, it is easy to reduce the bubbles caused by the decomposition gas of the AR polymer, or the bubbles caused by the gas generated by the reaction of the AR polymer itself, and effectively suppress the polymer layer in the laminated film. The interface of the polymer film is rough.

The AR polymer is preferably thermoplastic. Due to its plasticity, the AR polymer has further improved dispersibility in the polymer layer, and it is easy to form a dense and uniform polymer layer. The AR polymer is preferably at least one selected from the group consisting of aromatic polyimide, aromatic maleimide, aromatic polyphenylene ether, aromatic styrene elastomer, and liquid crystal polyester , more preferably aromatic polyimide. Here, the thermoplastic polyimide means a polyimide that has completed imidization and does not undergo further imidization reaction. If such an AR polymer is used, not only the adhesiveness of the polymer layer to the polymer film, but also the physical properties (UV absorption, etc.) of the film can be easily improved.

Specific examples of AR polymers include "HPC" series (manufactured by Hitachi Chemical Co., Ltd.) as aromatic polyimide imide, and "Neopulim" series (Mitsubishi Gas Chemical) as aromatic polyimide. company), "SPIXAREA" series (manufactured by SOMAR), "Q-PILON" series (manufactured by PI Institute of Technology), "WINGO" series (manufactured by Wingo Technology), "TOHMIDE" series (manufactured by T&K TOKA), "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.) and "UPIA-AT" series (manufactured by Ube Industries, Ltd.). In addition, about the aromatic polyimide which is an AR polymer, the aromatic polyimide demonstrated in the following polymer film can be used.

As a suitable embodiment of the F polymer and the AR polymer in this method, the melting temperature of the F polymer is 285-320°C and the glass transition point of the AR polymer is 315-335°C. In the above aspect, in the polymer layer, not only the F polymer and the AR polymer are uniformly dispersed to easily improve the physical properties of the film, but also in a high temperature environment, the F polymer and the AR polymer highly interact, and it is easy to further improve the film properties. Improve the heat resistance of the polymer layer.

In the liquid composition in this method, the content of the AR polymer is preferably 10% by mass or less, more preferably 7.5% by mass or less, and still more preferably 5% by mass relative to the total content of the F polymer and the AR polymer. mass % or less. Moreover, it is preferable that content of the said AR polymer is 0.1 mass % or more. If the content of each of the F polymer and the AR polymer in the liquid composition satisfies the above ratio, and the content of the AR polymer is relatively low relative to the content of the F polymer, in the obtained polymer layer , it is easy to form a state in which the AR polymer is highly dispersed in the F polymer. As a result, in the polymer layer, the physical properties (electrical properties, low water absorption, etc.) based on the F polymer are likely to be highly exhibited.

From the viewpoint of improving the electrical properties and low linear expansion of the polymer layer, the liquid composition in this method may further contain an inorganic filler. The inorganic fillers are preferably nitride fillers or inorganic oxide fillers, more preferably boron nitride fillers, beryllium oxide fillers (fillers of beryllium oxides), silicate fillers (silica fillers, wollastonite fillers) , talc filler), or metal oxide (cerium oxide, aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, etc.) filler, and more preferably silica filler. The inorganic filler is preferably surface-treated with a silane coupling agent.

The 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 can be any of granular, needle-like (fibrous), and plate-like. Specific shapes of inorganic fillers include spherical, scaly, lamellar, leaf-shaped, almond-shaped, columnar, cockscomb, equiaxed, leaf-shaped, mica-shaped, massive, flat, wedge-shaped Shape, rosette, reticulate, angular column.

Suitable specific examples of inorganic fillers include silica fillers ("Admafine (registered trademark)" series manufactured by Admatechs, etc.), zinc oxide fillers ( "FINEX (registered trademark)" series manufactured by Sakai Chemical Industry Co., Ltd., etc.), spherical fused silica filler ("SFP (registered trademark)" series manufactured by DENKA Corporation, etc.), polyols and inorganic substances. Coated titanium oxide filler (“Tipaque (registered trademark)” series manufactured by Ishihara Sangyo Co., Ltd., etc.), surface-treated rutile-type titanium oxide filler (“JMT (registered trademark)” manufactured by Tayca Corporation) ” series, etc.), hollow silica fillers (“E-SPHERES” series manufactured by Pacific Cement Corporation, “SiliNax” series manufactured by Nippon Steel Mining Corporation, “Ecco sphere” series manufactured by Emerson & Cuming Corporation, etc.), Talc fillers (“SG” series manufactured by Nippon Talc Co., Ltd., etc.), block talc fillers (“BST” series manufactured by Nippon Talc Co., Ltd., etc.), boron nitride fillers (“UHP” series manufactured by Showa Denko Co., Ltd., and DENKA Co., Ltd. "DENKA BORON NITRIDE" series ("GP", "HGP" grades), etc.).

From the viewpoint of improving dispersibility and workability, the liquid composition in this method may further contain a surfactant. The surfactant is preferably nonionic. The hydrophilic part of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group. The hydrophobic portion of the surfactant preferably has an acetylene group, a polysiloxane group, a perfluoroalkyl group or a perfluoroalkenyl group. In other words, the surfactant is preferably an acetylene-based surfactant, a polysiloxane-based surfactant or a fluorine-based surfactant, more preferably a polysiloxane-based surfactant. The surfactant may also be a glycol-based surfactant. One type of surfactant may be used, or two or more types may be used. In the case of using two kinds of surfactants, it is preferable to use a polysiloxane-based surfactant and a glycol-based surfactant.

Furthermore, the liquid composition in this method may contain, in addition to the above-mentioned components, a silane coupling agent, a dehydrating agent, an antifoaming agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antifoaming agent, a Additives such as electrostatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, flame retardants, organic fillers, etc.

The viscosity of the liquid composition is preferably 100 mPa·s or more, more preferably 250 mPa·s or more. The viscosity of the liquid composition is preferably 100,000 mPa·s or less, more preferably 10,000 mPa·s or less, and still more preferably 3,000 mPa·s. The thixotropy ratio of the liquid composition is preferably 1.0 to 2.0. The liquid composition with such viscosity and thixotropic ratio is easy to wet and spread on the surface of the polymer film more uniformly.

In this method, as the treatment performed on the surface of the polymer film, a hydrophilization treatment is preferable. According to the hydrophilization treatment, the surface tension of the surface of the polymer film can be increased relatively simply. The hydrophilic treatment is preferably a physical activation treatment such as corona treatment, plasma treatment, glow treatment, UV ozone treatment, and more preferably at least one treatment selected from the group consisting of corona treatment and plasma treatment. According to these treatments, the hydrophilization treatment can be performed relatively easily and surely.

From the viewpoint of efficiently introducing polar functional groups, the corona treatment is preferably performed in the presence of a flammable gas (vinyl acetate, etc.). As a plasma irradiation device in plasma treatment, a high frequency induction system, a capacitive coupling electrode system, a corona discharge electrode-plasma jet system, a parallel plate type, a remote plasma type, and an atmospheric pressure plasma type can be exemplified. , ICP (Inductive Coupling Plasma, Inductively Coupled Plasma) type high-density plasma type, etc. The gas used in the plasma treatment is preferably a rare gas, hydrogen or nitrogen. Specific examples of such a gas include: argon; a mixed gas of hydrogen and nitrogen; and a mixed gas of hydrogen, nitrogen, and argon.

Preferably, polar functional groups are present on the surface of the polymer film subjected to the above treatment. If polar functional groups exist on the surface of the polymer film, the surface tension (wettability) and adhesion of the surface will increase. Therefore, the uniformity of the thickness of the obtained polymer layer is improved, and the adhesion strength between the polymer film and the polymer layer is further improved. In addition, the effect of reducing the linear expansion coefficient of the polymer film can also be expected. The polar functional group present on the surface of the polymer film is preferably a hydroxyl group-containing group or a carbonyl group-containing group. Furthermore, the polymer film can be annealed to adjust its residual stress. The conditions in the annealing treatment are preferably as follows: the temperature is 120-180° C., the pressure is 0.005-0.015 MPa, and the time is 30-120 minutes.

It is preferable that the surface tension of the surface of the polymer film subjected to the above treatment is larger than the surface tension of the liquid dispersion medium. In this case, the liquid composition tends to wet and spread more smoothly and uniformly on the surface of the polymer film. Specifically, the difference between the surface tension of the treated polymer film and the surface tension of the liquid dispersion medium is preferably 10 mN/m or more, more preferably 20 mN/m or more. The difference in surface tension is preferably 50 mN/m or less, more preferably 40 mN/m or less. In addition, the arithmetic mean roughness Ra of the surface of the polymer film is preferably 0.01 to 5 μm, more preferably 0.03 to 1 μm. In this case, since the level difference which becomes the starting point of the pinning phenomenon is small, the liquid composition is more likely to wet and spread on the surface of the polymer film more uniformly.

When the liquid composition (polymer layer) contains the AR polymer, the glass transition point of the base polymer contained in the polymer film and the AR polymer contained in the liquid composition (polymer layer) The absolute value of the difference between the glass transition points is preferably 20°C or lower, more preferably 10°C or lower. In addition, the absolute value of the difference of the glass transition point may be 0 degreeC. In this case, the glass transition point of the base polymer is close to the glass transition point of the AR polymer, so that the entire laminated film is less likely to be deformed by heating. The specific value of the glass transition point of the base polymer contained in the polymer film is preferably 230 to 340°C, more preferably 250 to 320°C. In this case, the deformation of the polymer film caused by heating becomes sufficiently low.

If the absolute value of the difference between the glass transition points and the specific value of the glass transition point of the base polymer satisfy the above ranges, the generation of wrinkles on the surface of the obtained laminated film can be prevented or suppressed. The base polymer contained in the polymer film is preferably an aromatic polyimide. If an aromatic polyimide is used, the degree of deformation of the polymer film by heating tends to be lower. The content of the base polymer in the polymer film is preferably 80% by mass or more, more preferably 90% by mass or more. The said content may be 100 mass %.

Examples of the base polymer include polyimide, polyamide, polyetherimide, polyphenylene sulfide, polyallyl ether ketone, polyamideimide, liquid crystalline polyester, and tetrafluoroethylene. is a polymer, preferably an aromatic polyimide.

The imide group density of the aromatic polyimide as the base polymer is preferably 0.20 to 0.35. When the imide group density is below the above-mentioned upper limit value, the water absorption rate of the polymer film becomes lower, and it becomes easy to suppress the change in the dielectric properties of the laminated film. When the imide group density is equal to or higher than the above lower limit value, not only the imide group functions as a polar group to further improve the adhesion between the polymer film and the polymer layer, but also the water absorption rate tends to be significantly reduced. Moreover, when the said imide group density exists in such a range, it becomes difficult to generate|occur|produce a wrinkle in a laminated film. Such wrinkles are less likely to occur when the glass transition point of the aromatic polyimide in the polymer film is high.

Furthermore, the density of imide groups is determined by dividing the molecular weight (140.1) per unit of the imide moiety by the polyimide in the polyimide obtained by imidizing the polyimide precursor. The value obtained per unit of molecular weight. For example, a polyimide precursor containing 1 mole of pyromellitic dianhydride (molecular weight: 218.1) and 1 mole of 3,4'-diaminodiphenyl ether (molecular weight: 200.2) The imide group density of the polyimide (molecular weight per unit: 382.2) obtained by imidization is 0.37, which is the value obtained by dividing 140.1 by 382.2.

The aromatic polyimide may, for example, be a polyimide, which is obtained by reacting a diamine with a carboxylic dianhydride to synthesize a polyimide, followed by a thermal imidization method or a chemical imidization method. It is obtained by imidization of this polyamic acid. As a solvent for synthesizing polyamide acid, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone may, for example, be mentioned.

As the diamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3' -Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 1 ,4-Diaminobenzene (p-phenylenediamine), 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1, 3-bis(3-aminophenoxy)benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2'-dimethyl-4 ,4'-diaminobiphenyl, 2,2-bis{4-(4-aminophenoxy)phenyl}propane, 3,3'-dihydroxy-4,4'-diamino-1 , 1'-biphenyl, 2,4-diaminotoluene. These diamine components may be used individually by 1 type, and may use 2 or more types together.

As carboxylic dianhydride, pyromellitic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride may, for example, be mentioned. Anhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-bis Carboxyphenyl) 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, 3,3 ',4,4'-benzophenone tetracarboxylic dianhydride, 2,3,2',3'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-diphenylmethane Ketotetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethylbicyclohexane dianhydride, 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. These dicarboxylic acid components may be used individually by 1 type, and may use 2 or more types together.

Furthermore, the total molar number of oxygen atoms derived from ether bonds contained in the diamine and the carboxylic dianhydride is preferably 35 to 70%, more preferably 45, relative to the total molar number of the diamine and the carboxylic dianhydride. ~65%. In this case, the flexibility of the polymer main chain of the aromatic polyimide is improved, the stackability of the aromatic rings is improved, and the adhesion between the polymer film and the polymer layer is further improved. Moreover, in this case, the UV processability of the laminated film is also more favorable. Inorganic fillers can also be added to this polymer film to improve the properties of yield strength, difficult plastic deformation, thermal conductivity, ring stiffness and the like. Examples of such inorganic fillers include silicon oxide, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, and calcium phosphate.

The polymer film preferably has a higher yield strength. Specifically, the stress at 5% strain of the polymer film is preferably 180 MPa or more, more preferably 210 MPa or more. The stress at the above-mentioned 5% strain is preferably 500 MPa or less. Furthermore, the polymer film is preferably difficult to plastically deform. Specifically, the stress at 15% strain of the polymer film is preferably 225 MPa or more, more preferably 245 MPa or more. The stress at the above-mentioned 15% strain is preferably 580 MPa or less. If the polymer film has high yield strength, especially low plastic deformability, it is easy to sufficiently reduce the absolute value of the linear expansion coefficient of the laminated film, and the occurrence of warpage can be more reliably prevented.

The tensile modulus of elasticity of the polymer film at 320° C. is preferably 0.2 GPa or more, more preferably 0.4 GPa or more. The tensile modulus of elasticity is preferably 10 GPa or less, more preferably 5 GPa or less. The laminated film in this case is excellent in workability even if it is heated and cooled during processing. That is, if the tensile modulus of elasticity of the polymer film is equal to or higher than the above lower limit value, the shrinkage of the polymer layer will be effectively alleviated by the elasticity of the polymer film during heating and cooling during processing, and the laminated film will not be easily generated. Wrinkles easily improve the physical properties (surface smoothness, etc.) of the obtained laminated film. This tendency becomes significant when the content of F polymer in the polymer layer or the thickness of the polymer layer is larger. Moreover, when the tensile modulus of elasticity of the polymer film is equal to or less than the above-mentioned upper limit value, the flexibility of the laminated film is likely to be further improved.

The polymer film is preferably in direct contact with the polymer layer. That is, it is preferable to form (laminate) the polymer layer directly on the surface of the polymer film, without performing surface treatment with a silane coupling agent, an adhesive, or the like. In this case, in the obtained laminated film, film physical properties are less likely to decrease. Furthermore, with the above configuration, even if the polymer film and the polymer layer are in direct contact, high adhesion is exhibited between the polymer film and the polymer layer.

The method of applying the liquid composition to the polymer film may be any method as long as a stable liquid coating film containing the liquid composition is formed on the surface of the polymer film, and examples include spray method, roll coating Cloth method, spin coating method, gravure coating method, micro gravure coating method, gravure offset printing method, blade coating method, contact coating method, rod coating method, die nozzle coating method, injection Mylar rod method, slit die nozzle coating method.

When heating the polymer film on which the liquid coating film is formed, it is preferable to keep the temperature in the low temperature range, and to remove the liquid dispersion medium, that is, to perform drying. Thereby, a dry coating can be obtained. The temperature in the low temperature range is preferably 80°C or higher and less than 180°C. The temperature in the low temperature range means the temperature of the atmosphere in drying. The holding at the temperature in the low temperature range may be carried out in one stage, or may be carried out in two or more stages at different temperatures. The atmosphere when the temperature is kept in the low temperature range can be either under normal pressure or under reduced pressure. In addition, the atmosphere may be any of an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, a rare gas, and an inert gas atmosphere such as nitrogen.

In this method, it is preferable to further heat the dry film in a temperature range exceeding the holding temperature in the low temperature range (hereinafter, also referred to as "calcination range"), and calcine the F powder (F polymer) to polymerize. A polymer layer is formed on the surface of the film. The temperature in the firing range means the temperature of the atmosphere during firing. It is considered that the particles of the F powder are tightly packed, and the F powder (F polymer) is fused to form a polymer layer. Furthermore, when the liquid composition contains a thermosetting AR polymer, a polymer layer comprising a mixture of the F polymer and the AR polymer is formed, and when the liquid composition contains a thermosetting AR polymer, a polymer layer is formed. A polymer layer comprising a hardened product of F polymer and AR polymer.

The atmosphere during the calcination may be in any state under normal pressure or under reduced pressure. In addition, the atmosphere may be any of an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, a rare gas, and an inert gas atmosphere such as nitrogen. The atmosphere during the calcination is preferably a gas atmosphere containing an inert gas and a low oxygen concentration, more preferably a gas atmosphere containing nitrogen and an oxygen concentration (based on volume) of less than 500 ppm. Oxygen concentration (on a volume basis) is usually above 1 ppm. Within this range, the oxidative decomposition of the polymer component is easily suppressed, and the adhesiveness of the polymer layer is improved. The temperature in the calcination range is preferably higher than the melting temperature of the F polymer, more preferably 300 to 380°C. The time for maintaining the temperature in the firing range is preferably 30 seconds to 5 minutes, more preferably 1 to 2 minutes.

When the polymer layers are formed on both sides of the polymer film, it is preferable to apply the liquid composition to one surface of the polymer film, remove the liquid dispersion medium by heating, and apply the liquid composition to the other surface of the polymer film. The composition is heated to remove the liquid dispersion medium, and the F polymer is further heated to calcine the F polymer to form the respective polymer layers, thereby obtaining a laminated film. A laminated film having a polymer layer on both surfaces of a polymer film can be obtained by applying a liquid composition to both surfaces of the polymer film, heating to remove the liquid dispersion medium, and heating to bake F-polymerization material, thereby simultaneously forming polymer layers on both surfaces.

The laminated film having the polymer layer on both surfaces of the polymer film is preferably obtained by immersing the polymer film in the liquid composition to give the liquid composition to both surfaces of the polymer film, and then heating it in a calciner. . Specifically, after immersing the polymer film in the liquid composition, it is more preferably obtained by heating the polymer film in a baking furnace while being pulled from the liquid composition. The direction in which the polymer film is pulled and passed through the calciner is preferably vertically upward. In this case, a smooth polymer layer is easily formed. After the polymer film is pulled up vertically, it can be further heated while being pulled down vertically, or it can be pulled down vertically without heating, thereby pulling the polymer film. In addition, the amount of the liquid composition to be applied to the polymer film can be adjusted by passing the polymer film to which the liquid composition adhered between a pair of rolls. Such a laminated film can be suitably produced using an apparatus having a dip coater and a baking furnace. As the roasting furnace, a vertical roasting furnace may, for example, be mentioned. Moreover, as such an apparatus, the glass cloth coating apparatus manufactured by Tatabata Machinery Co., Ltd. can be mentioned.

The average thickness of the polymer film is preferably 10 μm or more, more preferably 15 μm or more. The average thickness of the polymer film is preferably 500 μm or less, more preferably 100 μm or less. The average thickness of the polymer layer is preferably 10 μm or more, more preferably 15 μm or more. The average thickness of the polymer layer is preferably 500 μm or less, more preferably 100 μm or less. If the liquid composition in this method is used, a relatively thick polymer layer with less uneven thickness can be formed. Moreover, the average thickness of the laminated film is preferably 30 μm or more, more preferably 40 μm or more. The average thickness of the laminated film is preferably 1000 μm or less, more preferably 200 μm or less.

The laminated film of the present invention (hereinafter, also referred to as "this laminated film") includes: a polymer film having a surface treated to increase surface tension; and a polymer layer formed on the surface and containing the F polymer . Furthermore, in such a present laminated film, the ratio of the thickness of the edge portion of the polymer layer to the thickness of the central portion is 1.1 or less, preferably 1.07 or less, and more preferably 1.04 or less. A polymer layer satisfying such a thickness relationship can be said to have a small thickness variation. The laminated film is preferably a long strip. In this case, it is preferable that the ratio of the thickness at the center of the laminated film in the width direction (short-side direction: CD direction (cross direction)) to the thickness at the ends in the width direction satisfies the above relationship. In this case, if the thickness of the polymer layer satisfies the above-mentioned relationship when the long present laminated film is wound into a roll shape and stored, wrinkles are less likely to occur at the ends in the width direction.

Furthermore, the length of the long-side direction (MD direction (Machine direction, machine direction)) of the elongated laminated film is preferably 1-1000 m, and the length of the short-side direction (CD direction) is preferably 100-10000 mm . In addition, the definition and scope of the F polymer and AR polymer in this laminated film, including suitable aspects, are the same as those in this Act. In addition, the range of the composition and physical properties in this laminated film, including suitable aspects, are the same as those in this Act. The laminated film may have a polymer layer only on one side of the polymer film, or may have a polymer layer on both sides of the polymer film, and the latter is preferred. In the latter case, it is easy to prevent warpage of the laminated film.

When the present laminated film has polymer layers on both sides of the polymer film, the ratio of the total average thickness of the two polymer layers to the average thickness of the polymer film is preferably 1 or more. The above-mentioned comparison is preferably 3 or less. In this case, the physical properties of the base polymer in the polymer film (high yield strength, difficult plastic deformation, etc.) and the physical properties of the F polymer in the polymer layer (low dielectric constant, low dielectric constant, etc.) Electrical properties such as electrical dissipation factor, low water absorption, etc.). Moreover, even in the present laminated film which is relatively large and the polymer layer is thick, it is easy to suppress warpage and peeling. In particular, when the tensile modulus of elasticity of the polymer film is equal to or higher than the above lower limit value, this tendency tends to become remarkable.

Also, the thicknesses of the two polymer layers are preferably equal. In this case, the linear expansion coefficients of the two polymer layers are closer, so the laminated film is less likely to warp. The dielectric constant of the laminated film is preferably 2.0 to 3.0. In this case, the present laminated film can be suitably used for a printed circuit board material or the like requiring a low dielectric constant. The dielectric loss factor of the laminated film is preferably 0.0001 to 0.0020.

The absolute value of the linear expansion coefficient of the laminated film is preferably 30 ppm/°C or less, more preferably 20 ppm/°C or less, and still more preferably 10 ppm/°C or less. In this case, irrespective of the temperature of the atmosphere in which the laminated film is arranged, etc., the occurrence of warpage of the laminated film can be effectively prevented. The lower limit of the absolute value of the linear expansion coefficient of the laminated film is 0 ppm/°C. The peel strength between the polymer layer and the polymer film in the laminated film is preferably 10 N/cm or more, more preferably 15 N/cm or more, and still more preferably 20 N/cm or more. The upper limit of the peel strength of the laminated film is 100 N/cm.

In addition, this laminated film exhibits low water absorption (high water barrier properties). The reason for this is considered to be that the polymer layer and the polymer film exist independently of each other, rather than being a compatible integrated body, so the low water absorption of the F polymer complements the high water absorption of the base polymer. Specifically, the laminated film was pre-dried at 50°C for 48 hours, then immersed in pure water at 23°C for 24 hours, and the mass of the laminated film before and after the immersion in pure water was measured, based on the formula: Water absorption rate (%) = (mass after pure water immersion - mass after pre-drying) / mass after pre-drying × 100 The obtained water absorption is preferably 0.1% or less, more preferably 0.07% or less, and still more preferably 0.05% or less. The lower limit of the water absorption of this laminated film is 0%. The laminated film having such a low water absorption rate is not easily deformed by water absorption, so it is suitable for use as a printed circuit board material and the like.

Furthermore, the multilayer film containing AR polymer in the polymer layer has high ultraviolet (UV) absorption, and is suitable for use by lasers such as UV-YAG (ultraviolet-yttrium aluminum garnet, ultraviolet yttrium aluminum garnet) laser. processing. The reason for this is considered to be that, in the polymer layer, the AR polymer is highly dispersed, forms a certain matrix, and is uniformly distributed, so that the aromatic ring possessed by the AR polymer exhibits good UV absorption. Such a polymer layer can be easily formed into a through hole having a good shape by laser processing, so the laminate film having the polymer layer is particularly suitable for use as a printed circuit board material.

The polymer film is an aromatic polyimide film. This laminate film can be used as a release film or a carrier film. Since the present laminate film has excellent adhesion between the polymer layer and the polymer film, and interlayer peeling is unlikely to occur, it can be used repeatedly as a carrier film. Moreover, since the polymer layer is excellent in heat resistance, even if it is used repeatedly, the mold release property is not liable to deteriorate.

Specifically, a dispersion liquid or a varnish containing a resin or an inorganic filler is applied to the surface of the polymer layer of the present laminated film, dried to form a coating film, and then the present laminated film is peeled off from the coating film to obtain an independent the coating. For example, after the above-mentioned coating film is formed on the surface of the polymer layer of the present laminated film, the coating film side of the present laminated film having such a coating film is bonded to another substrate, and the present laminated film is peeled off to obtain other substrates. A laminate of material and coating film. When forming a coating film on the surface of the polymer layer of the present laminate film, for example, during drying, heating may be performed at a temperature below the melting point of the F polymer. Since this laminated film is excellent in heat resistance, it is hard to deform|transform even if it heat-processes repeatedly.

Specifically, the laminated film can be used as a carrier film for forming a ceramic green sheet, a carrier film for forming a secondary battery, a carrier film for forming a solid polymer electrolyte membrane, and a carrier film for forming a catalyst for a solid polymer electrolyte membrane. In the case of using the laminated film as a carrier film, from the viewpoint of obtaining the above-mentioned coating film with a uniform thickness, the ratio of the thickness of the end portion of the laminated film to the thickness of the central portion is preferably 1.1 or less, more preferably 1.07 or less, more preferably 1.04 or less. The thickness ratio is 1 or more.

Since this laminate film has excellent adhesiveness on the surface of the polymer layer, it can be easily and firmly bonded to other substrates. As another base material, a metal foil and a metal conductor are mentioned. For example, a metal foil laminate can be obtained by bonding metal foil to both surfaces of the laminate film. Then, by processing the metal foil, the metal foil laminate can be easily processed into a printed circuit board. As a metal which comprises a metal foil, copper, a copper alloy, stainless steel, nickel, a nickel alloy (Alloy 42 is also included), aluminum, an aluminum alloy, titanium, and a titanium alloy are mentioned. The metal foil is preferably a copper foil, more preferably a rolled copper foil with no distinction between the front and the back, or an electrolytic copper foil with a distinction between the front and the back, and more preferably a rolled copper foil. Since the surface roughness of the rolled copper foil is small, the transmission loss can be reduced even when the metal foil laminate is processed into a printed circuit board. Moreover, it is preferable that the rolled copper foil is immersed in a hydrocarbon-based organic solvent, and is used after removing the rolling oil.

The ten-point average roughness of the surface of the metal foil is preferably 0.01 to 4 μm. In this case, the adhesiveness with the polymer layer becomes favorable, and it becomes easy to obtain the printed circuit board which is excellent in the transmission characteristic. The surface of the metal foil can also be roughened. As a roughening process method, the method of forming a roughening process layer, a dry etching method, and a wet etching method are mentioned. The thickness of the metal foil may be a thickness sufficient to function in the application of the metal foil laminate. The thickness of the metal foil is preferably less than 20 μm, more preferably 2 to 15 μm. Also, a part of the surface or the entire surface of the metal foil may be treated with a silane coupling agent.

In the metal foil laminate, as a method of layering the metal foil on the surface area of the polymer layer, a method of hot-pressing the laminate film and the metal foil can be exemplified. The pressing temperature in the hot pressing is preferably 310 to 400°C. From the viewpoint of suppressing the incorporation of air bubbles and suppressing deterioration due to oxidation, the hot pressing is preferably performed at a degree of vacuum of 20 kPa or less. In addition, in the case of hot pressing, it is preferable to raise the temperature after reaching the above-mentioned degree of vacuum. If the temperature is raised before reaching the above-mentioned degree of vacuum, the polymer layer may be press-bonded in a softened state, that is, in a state having a certain degree of fluidity and adhesion, resulting in the generation of air bubbles. The pressure in the hot pressing is preferably 0.2 to 10 MPa from the viewpoint of suppressing breakage of the metal foil and making the polymer layer and the metal foil tightly adhered. In particular, when the tensile modulus of elasticity of the polymer film is equal to or more than the above lower limit value, it is easy to suppress the occurrence of wrinkles due to heating and cooling during hot pressing.

Metal foil laminates can be used as flexible copper foil laminates or rigid copper foil laminates to manufacture printed circuit boards. The printed circuit board can be produced, for example, by a method of processing the metal foil in the metal foil laminate into a conductor circuit (pattern circuit) of a specific pattern by etching or the like; or by a plating method (semi-additive method (SAP method) , improved semi-additive method (MSAP method, etc.) to process the metal foil laminate of the present invention into a pattern circuit. When manufacturing a printed circuit board, after forming a pattern circuit, an interlayer insulating film can be formed on the pattern circuit, and a conductor circuit can be formed on the interlayer insulating film, and a solder resist can also be laminated on the pattern circuit, and can also be laminated on the pattern circuit. membrane. The interlayer insulating film, the solder resist, and the cover film can be formed from the above-mentioned liquid compositions, respectively.

In the metal foil laminate, the peel strength between the metal foil and the laminate film is preferably 10 N/cm or more, more preferably 15 N/cm or more, and still more preferably 20 N/cm or more. The upper limit of the peel strength of the metal foil and the laminated film is usually 100 N/cm. According to this laminated film, deformation during thermocompression bonding is suppressed, so that it is bonded to the metal foil with high adhesiveness, and it is easy to obtain a metal foil laminate with high peel strength.

As mentioned above, although the manufacturing method and the laminated film of the laminated|multilayer film of this invention were demonstrated, this invention is not limited to the structure of the said embodiment. For example, other arbitrary structures may be added to the structure of the above-mentioned embodiment, and the laminated film of the present invention may be replaced with an arbitrary structure that exhibits the same function. Moreover, in the manufacturing method of the laminated|multilayer film of this invention, other arbitrary steps may be added to the structure of the above-mentioned embodiment, and the arbitrary steps which exhibit the same function may be replaced. [Example]

Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. 1. Preparation of each component [F polymer] F polymer 1: contains 98.0 mol % of TFE units, 0.1 mol % of NAH units and 1.9 mol % of PPVE units, and each 1 ×10 ⁶ PFA-based polymer having 1,000 carbonyl-containing groups (melting temperature: 300° C.) F polymer 2: contains 97.5 mol % of TFE units and 2.5 mol % of PPVE units, and relative to the main chain PFA-based polymer having 25 carbonyl-containing groups per 1×10 ⁶ carbon number (melting temperature: 305° C.) [Powder] Powder 1: D50 is 1.9 μm, Powder 2 containing F polymer 1: D50 is 2.0 μm, powder containing F polymer 2

[Liquid Dispersion Medium] Liquid Dispersion Medium 1: N-methyl-2-pyrrolidone (NMP: Surface Tension: 41 mN/m) Liquid Dispersion Medium 2: Toluene (Tol: Surface Tension: 27 mN/m) [ Surfactant] Surfactant 1: CH ₂ =C(CH ₃ )C(O)OCH ₂ CH ₂ (CF ₂ ) ₆ F and CH ₂ =C(CH ₃ )C(O)(OCH ₂ CH ₂ ) Copolymer of ₂₃ OH, nonionic polymer with a fluorine content of 35% by mass [varnish of AR polymer] Varnish 1: containing AR polymer 1 (glass transition point: 315°C) as aromatic polyimide NMP solution (solid content: 10% by mass) [Polymer film] Polyimide film 1: thickness of 50 μm, glass transition point of 315°C, imide group density of 0.25, tensile elasticity at 320°C Aromatic polyimide film with modulus 0.3 GPa

2. Preparation of liquid composition (liquid composition 1) After 67 parts by mass of the liquid dispersion medium 1, 3 parts by mass of the surfactant 1, and 30 parts by mass of the powder 1 were put into the crucible, zirconia balls were put into the crucible. Then, the crucible was rolled at 150 rpm for 1 hour to disperse the powder 1, and the liquid composition 1 was obtained. (Liquid composition 2) After 87 parts by mass of the liquid dispersion medium 1, 3 parts by mass of the surfactant 1, and 10 parts by mass of the powder 1 were put into the crucible, zirconia balls were put into the crucible. Then, the crucible was rolled at 150 rpm for 1 hour to disperse the powder 1, and the liquid composition 2 was obtained.

(Liquid Composition 3) Liquid Composition 3 was prepared in the same manner as Liquid Composition 1 except that Powder 1 was changed to Powder 2. (Liquid Composition 4) Liquid composition 4 was prepared in the same manner as liquid composition 3 except that liquid dispersion medium 1 was changed to liquid dispersion medium 2 . (Liquid Composition 5) After 70 parts by mass of the liquid dispersion medium 1 and 30 parts by mass of the powder 2 were put into the crucible, zirconia balls were put into the crucible. Then, the crucible was rolled at 150 rpm for 1 hour to disperse the powder 2, and a liquid composition 5 was obtained. (Liquid composition 6) After 57 parts by mass of the liquid dispersion medium 1, 10 parts by mass of the varnish 1, 3 parts by mass of the surfactant 1, and 30 parts by mass of the powder 1 were put into the crucible, zirconia balls were put into the crucible. Then, the crucible was rolled at 150 rpm for 1 hour to disperse the powder 1, and a liquid composition 6 was obtained.

3. Manufacture of laminated film (example 1) First, corona treatment was performed on both surfaces of the polyimide film 1 (surface tension: 35 mN/m, arithmetic mean roughness of the surface: 0.05 μm), and polar functional groups were introduced into the surfaces. Furthermore, the surface tension of the surface of the polyimide film 1 after the corona treatment was 78 mN/m. Next, the liquid composition 1 was coated on one surface of the polyimide film 1 by a small-diameter reverse gravure method, and passed through a ventilation drying oven (furnace temperature: 150° C.) for 3 minutes to remove NMP to form a dry coating. membrane. Furthermore, the other surface of the polyimide film 1 was also coated with the liquid composition 1 in the same manner, and dried to form a dry film. Next, the polyimide film 1 having the dry coating formed on both sides was passed through a far-infrared furnace (furnace temperature: 320° C.) for 20 minutes to melt and bake the powder 1 . Thereby, a polymer layer (thickness: 25 μm) containing the F polymer 1 was formed on both sides of the polyimide film 1, and the polymer layer, the polyimide film 1, and the polymer layer were directly formed in this order. The long layered film 1 of the object layer.

(Example 2) A polymer layer (thickness: 25 μm) containing the F polymer 1 was formed on both sides of the polyimide film 1 in the same manner as in Example 1 except that the liquid composition 2 was used instead of the liquid composition 1 to obtain a The above-mentioned polymer layer, the above-mentioned polyimide film 1, and the above-mentioned long-length laminated film 2 of the above-mentioned polymer layer are directly formed in this order. In addition, in the laminated film 2, in order to form a polymer layer with a thickness of 25 micrometers, it was necessary to repeat the operation of the application of the liquid composition 1 and the melt baking twice. (Example 3) A polymer layer (thickness: 25 μm) containing the F polymer 2 was formed on both sides of the polyimide film 1 in the same manner as in Example 1 except that the liquid composition 3 was used instead of the liquid composition 1 to obtain a The above-mentioned polymer layer, the above-mentioned polyimide film 1, and the above-mentioned long-length laminated film 3 of the above-mentioned polymer layer are directly formed in this order.

(Example 4) A polymer layer (thickness: 25 μm) containing the F polymer 2 was formed on both sides of the polyimide film 1 in the same manner as in Example 1 except that the liquid composition 4 was used instead of the liquid composition 1 to obtain a The above-mentioned polymer layer, the above-mentioned polyimide film 1, and the above-mentioned long-length laminated film 4 of the above-mentioned polymer layer are directly formed in this order. (Example 5) Except that the liquid composition 5 was used instead of the liquid composition 1, and the corona treatment on the surface of the polyimide film 1 was omitted, the polyimide film 1 was formed on both sides of the polyimide film 1 in the same manner as in Example 1. A polymer layer (thickness: 25 μm) of the F polymer 2 was obtained, and a long layered film 5 in which the above-mentioned polymer layer, the above-mentioned polyimide film 1 and the above-mentioned polymer layer were directly formed in this order was obtained. (Example 6) A polymer layer (thickness: 25 cm) comprising F polymer 1 and AR polymer 1 was formed on both sides of the polyimide film 1 in the same manner as in Example 1, except that the liquid composition 6 was used instead of the liquid composition 1. μm) to obtain a long layered film 6 in which the above-mentioned polymer layer, the above-mentioned polyimide film 1, and the above-mentioned polymer layer are directly formed in this order.

4. Evaluation 4-1. Appearance of the polymer layer In each laminated film, the surface of the polymer layer was visually observed and evaluated according to the following criteria. [Evaluation Criteria] ○: No unevenness was seen on the surface of the polymer layer, and it was relatively smooth. ×: Unevenness and unevenness are seen on the surface of the polymer layer.

4-2. Uniformity of thickness of polymer layer In each laminated film, the thickness of the center part and the edge part of the transversal direction of one polymer layer was measured, the ratio of the thickness of an edge part / the thickness of a center part was calculated|required, and it evaluated based on the following criteria. [Evaluation Criteria] ○: The thickness ratio is 1.07 or less. Δ: The thickness ratio exceeds 1.07 and is 1.1 or less. ×: The ratio of thickness exceeds 1.1.

4-3. Water absorption rate According to ASTM D570, each laminated film was pre-dried at 50°C for 48 hours, and then immersed in pure water at 23°C for 24 hours. After measuring the mass of the laminated film before and after immersion in pure water, the water absorption rate was calculated|required based on the following formula, and it evaluated based on the following criteria. Water absorption rate (%) = (mass after pure water immersion - mass after pre-drying) / mass after pre-drying × 100 [Evaluation Criteria] ⊚: Water absorption is 0.05% or less. ○: The water absorption rate exceeds 0.05% and is 0.07% or less. △: The water absorption rate exceeds 0.07% and is 0.1% or less. ×: The water absorption rate exceeds 0.1%.

4-4. Peel strength A rectangular test piece having a length of 100 mm and a width of 10 mm was cut out from each laminated film. Then, the polyimide film 1 and the polymer layer were peeled off to a position 50 mm from one end in the longitudinal direction of the test piece. Then, with a position 50 mm from one end in the longitudinal direction of the test piece as the center, a tensile tester (manufactured by Orientec) was used to perform 90-degree peeling at a tensile speed of 50 mm/min, and the maximum load was defined as the peel strength ( N/cm), and evaluated according to the following evaluation criteria. [Evaluation Criteria] ○: The peel strength is 15 N/cm or more. Δ: The peel strength is 10 N/cm or more and less than 15 N/cm. ×: The peel strength was less than 10 N/cm.

4-5. Dielectric loss factor The dielectric loss factor of each laminated film at 10 GHz was measured by the SPDR (Split Post Dielectric Resonator) method, and evaluated according to the following evaluation criteria. [Evaluation Criteria] ◎: The dielectric loss factor is 0.0015 or less. ○: The dielectric loss factor exceeds 0.0015 and is 0.0020 or less. Δ: The dielectric loss factor exceeds 0.0020 and is 0.0030 or less. ×: The dielectric loss factor exceeds 0.0030. The above results are shown in Table 1 below.

[Table 1] Laminated Film No. 1 2 3 4 5 6 liquid composition F polymer 1 1 2 2 2 1 liquid dispersion medium NMP NMP NMP Tol NMP NMP With or without surfactant Have Have Have Have none Have With or without AR polymer none none none none none Have Powder content [mass%] 30 15 30 30 30 30 With or without corona treatment Have Have Have Have none none Thickness of each layer [μm] 25/50/25 25/50/25 25/50/25 25/50/25 25/50/25 25/50/25 Exterior ○ ○ ○ × ○ ○ uniformity of thickness ○ ○ ○ - × ○ water absorption ○ ○ △ × × ◎ peel strength ○ ○ △ × × ○ Dielectric Dissipation Factor ○ ○ △ - - ◎ [Industrial Availability]

The laminated film of the present invention is excellent in peel strength (adhesion), and the uniformity of the thickness of the polymer layer is high. Therefore, such a laminated film can be processed and used as antenna parts, printed circuit boards, aircraft parts, automobile parts, and the like.

Claims (15)

A method for producing a laminated film, comprising coating a liquid composition on the surface of a polymer film subjected to a treatment for increasing surface tension, and heating to obtain a laminated film in which a polymer layer is formed on the surface of the polymer film The liquid composition contains tetrafluoroethylene polymer powder and a liquid dispersion medium with a surface tension of 30 mN/m or more, and the content of the powder is 10 mass % or more. The manufacturing method of claim 1, wherein the above-mentioned treatment is at least one hydrophilization treatment selected from the group consisting of corona treatment and plasma treatment. The production method of claim 1 or 2, wherein the surface tension of the surface of the polymer film subjected to the above treatment is greater than the surface tension of the liquid dispersion medium. The production method according to any one of claims 1 to 3, wherein the arithmetic mean roughness Ra of the surface of the polymer film is 0.01 to 5 μm. The production method according to any one of claims 1 to 4, wherein polar functional groups exist on the surface of the polymer film subjected to the above treatment. The production method according to any one of claims 1 to 5, wherein the average particle size of the powder is 0.1 to 10 μm. The production method according to any one of claims 1 to 6, wherein the tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having a melting temperature of 260 to 320°C. The production method according to any one of claims 1 to 7, wherein the tetrafluoroethylene-based polymer contains perfluoro(alkyl vinyl ether)-based units, and contains 1.5 to 5.0 mol % of all units. Tetrafluoroethylene-based polymers based on units of perfluoro(alkyl vinyl ether). The production method according to any one of claims 1 to 8, wherein the liquid composition contains an aromatic polymer. The production method according to any one of claims 1 to 9, wherein the polymer film contains an aromatic polyimide. The production method according to any one of claims 1 to 10, wherein the average thickness of the polymer film is 10 μm or more, and the average thickness of the polymer layer is 10 μm or more. A laminated film comprising: a polymer film having a surface treated to increase surface tension; and a polymer layer formed on the surface, containing a tetrafluoroethylene-based polymer, and an end portion of the polymer layer The ratio of the thickness to the thickness of the central portion is 1.1 or less. The laminated film of claim 12, wherein the laminated film is pre-dried at 50°C for 48 hours, and then immersed in pure water at 23°C for 24 hours, and the properties of the laminated film before and after immersion in pure water are measured In the case of mass, the water absorption rate calculated based on the following formula is 0.1% or less; Water absorption rate (%)=(mass after pure water immersion−mass after pre-drying)/mass after pre-drying×100. The laminated film of claim 12 or 13, wherein the average thickness of the polymer film is 10 μm or more, and the average thickness of the polymer layer is 10 μm or more. The laminate film according to any one of claims 12 to 14, wherein the polymer layer is provided on both sides of the polymer film.