Film, method for manufacturing surface-treated film, laminate, and method for manufacturing surface-treated laminate

Abstract

To provide a film that has excellent resistance to surface roughness when subjected to plasma treatment and also has excellent heat resistance, a laminate and a method for producing a laminate.SOLUTION: A film disclosed herein contains a tetrafluoroethylene polymer with a melting temperature of 260-320°C, and a polymer other than the tetrafluoroethylene polymer, and has a moisture content of 0.01-4 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a film, a method for producing a surface-treated film, a laminate, and a method for producing a surface-treated laminate. [Background technology]

[0002] Tetrafluoroethylene-based polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as chemical resistance, water and oil repellency, heat resistance, and electrical properties, and are known to be used in a variety of applications that utilize these physical properties. In recent years, tetrafluoroethylene-based polymers have been used to produce metal-clad laminates that can be processed into printed circuit boards with excellent electrical properties and heat resistance. For example, Patent Document 1 discloses that a metal-clad laminate is produced by forming a polymer layer on the surface of a metal substrate layer using a powder dispersion containing a tetrafluoroethylene-based polymer powder, a (meth)acrylate-based polymer, a polyimide precursor or polyimide, and a polar organic solvent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 137879 Summary of the Invention [Problem to be solved by the invention]

[0004] The metal clad laminate is required to have various properties depending on its application. For example, the polymer layer may be subjected to plasma treatment for the purposes of controlling the linear expansion coefficient and improving adhesion with adjacent layers such as a substrate layer. If the polymer layer contains an inorganic filler for the purpose of controlling the linear expansion coefficient, the inorganic filler may fall off due to the plasma treatment, causing the surface of the polymer layer to become rough, which may result in an inability to control the linear expansion coefficient or a decrease in thermal conductivity. Therefore, the polymer layer may be required to have excellent surface roughness suppression properties. Furthermore, there is a tendency for a higher degree of heat resistance to be required, so that the adhesion between the polymer layer and the layer adjacent to the polymer layer can be maintained even when the polymer layer is left in a high-temperature environment.

[0005] An object of one embodiment of the present disclosure is to provide a film, a laminate, and a method for manufacturing a laminate that are excellent in surface roughness suppression and heat resistance. [Means for solving the problem]

[0006] Means for solving the above problems include the following aspects. <1> A film containing a tetrafluoroethylene-based polymer having a melting temperature of 260 to 320°C and a polymer other than the tetrafluoroethylene-based polymer, and having a water content of 0.01 to 4% by mass. <2> At least one of the tetrafluoroethylene-based polymer and the polymer other than the tetrafluoroethylene-based polymer has a carbonyl group-containing group. <1> The film according to claim 1. <3> The carbonyl group-containing group is one or more groups selected from the group consisting of an acid anhydride group, a carboxyl group, and a maleimide group. <2> The film according to claim 1. <4> The polymer other than the tetrafluoroethylene-based polymer is one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins. <1> ~ <3> 10. The film according to any one of the preceding items. <5> The content of the tetrafluoroethylene polymer relative to the total mass of the film is 75 to 99 mass %. <1> ~ <4> 10. The film according to any one of the preceding items. <6> The above composition further containing an inorganic filler. <1> ~ <5> 10. The film according to any one of the preceding items. <7> the above <1> ~ <6> A method for producing a surface-modified film, comprising plasma-treating the surface of the film described in any one of the above items to obtain a surface-modified film. <8> A laminate comprising a substrate layer and a polymer layer containing a tetrafluoroethylene-based polymer having a melting temperature of 260 to 320°C and a polymer other than the tetrafluoroethylene-based polymer, and having a water content of 0.01 to 4 mass %. <9> At least one of the tetrafluoroethylene-based polymer and the polymer other than the tetrafluoroethylene-based polymer has a carbonyl group-containing group. <8> The laminate according to claim 1. <10> The carbonyl group-containing group is one or more groups selected from the group consisting of an acid anhydride group, a carboxyl group, and a maleimide group. <9> The laminate according to claim 1. <11> The polymer other than the tetrafluoroethylene-based polymer is one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins. <8> ~ <10> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the <12> The content of the tetrafluoroethylene-based polymer relative to the total mass of the polymer layer is 75 to 99 mass %. <8> ~ <11> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the <13> The above composition further containing an inorganic filler. <8> ~ <12> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the <14> The substrate layer is a metal substrate layer or a film layer containing a polyimide resin. <8> ~ <13> 10. The laminate according to claim 9, wherein the first and second laminates are oriented in a direction perpendicular to the plane of the <15> the above <8> ~ <14> 10. A method for producing a surface-modified laminate, comprising plasma-treating a surface of the polymer layer of the laminate described in any one of 1 to 9, to obtain a laminate having a surface-modified polymer layer. [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, it is possible to provide a film, a laminate, and a method for manufacturing a laminate, which are excellent in surface roughness suppression and heat resistance. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, modes for carrying out embodiments of the present disclosure will be described in detail. However, the embodiments of the present disclosure are not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the embodiments of the present disclosure.

[0009] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, multiple types of particles corresponding to each component may be contained. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "lamination" refers to stacking layers, and two or more layers may be bonded together, or two or more layers may be detachable. In the present disclosure, the "moisture content" is determined by cutting a 10 cm x 10 cm test piece from a film of the present disclosure or a polymer layer of a laminate of the present disclosure, measuring the mass Wi of the test piece in its initial state (water-containing state), and then measuring the mass Wo of the test piece after heat treatment at 150°C for 30 minutes, and then calculating the moisture content from the following formula: When the laminate of the present disclosure has a structure in which substrate layers are provided on both sides of the polymer layer, such as substrate layer / polymer layer / substrate layer, as described below, at least one of the substrate layers is removed to prepare the test piece. Moisture percentage (mass%) = 100 × (Wi-Wo) / Wo In the present disclosure, the "average particle diameter (D50)" refers to the volume-based cumulative 50% diameter of particles determined by laser diffraction / scattering. That is, the particle size distribution is measured by laser diffraction / scattering, and a cumulative curve is calculated with the total volume of the particle population set as 100%. The "average particle diameter (D50)" is the particle diameter at the point on the cumulative curve where the cumulative volume is 50%. The D50 of particles can be determined by dispersing the particles in water and analyzing them by a laser diffraction / scattering method using a laser diffraction / scattering particle size distribution measuring device (for example, LA-920 measuring device manufactured by Horiba, Ltd.). In the present disclosure, the "melting temperature" is the temperature corresponding to the maximum value of the melting peak of a polymer as measured by differential scanning calorimetry (DSC). In the present disclosure, the "weight average molecular weight" is determined using gel permeation chromatography (GPC) in terms of polystyrene. In the present disclosure, the "glass transition temperature (Tg)" is a value measured by analyzing a polymer using a dynamic mechanical analysis (DMA) method. In the present disclosure, a "polymer" is a compound formed by polymerizing a monomer, i.e., a "polymer" has a plurality of units based on the monomer. In the present disclosure, the term "unit" in a polymer refers to an atomic group based on a monomer formed by polymerization of the monomer. The unit may be a unit formed directly by a polymerization reaction, or may be a unit in which a part of the unit is converted into a different structure by treating the polymer. In the present disclosure, the ten-point mean roughness is measured in accordance with the provisions of JIS B 0601 (1994) "Surface roughness - definition and indication." The ten-point mean roughness can be measured, for example, using a high-precision shape measuring system (for example, "KS-1100" manufactured by Keyence Corporation, tip head model number "LT-9510VM") or the like.

[0010] The film of the present disclosure (hereinafter also referred to as "F film") contains a tetrafluoroethylene-based polymer (hereinafter also referred to as "F polymer") having a melting temperature of 260 to 320°C, and a polymer other than the tetrafluoroethylene-based polymer (hereinafter also referred to as "A polymer"), and has a water content of 0.01 to 4 mass%. From the viewpoints of suppressing surface roughness and heat resistance, the water content is preferably 0.03 to 2 mass%, more preferably 0.05 to 1 mass%. The method for adjusting the water content is not particularly limited, and may be performed by humidifying or drying the F film, or by adjusting the water content of a composition used in producing the F film.

[0011] F films have excellent surface roughness suppression and heat resistance. While the mechanism of action is unclear, it is generally assumed as follows. When plasma treatment is performed on an F film with a water content of 0.01% by mass or more, active species (such as hydroxyl radicals) are generated from the water contained in the F film. These active species highly introduce oxygen atoms into the F polymers present at a certain depth from the outermost surface of the F film. The introduced oxygen atoms then form hydrophilic groups such as hydroxyl groups and carbonyl groups in the F polymers, promoting interactions such as crosslinking between the F polymers and between the F polymers and the A polymer. In other words, it is assumed that a sophisticated matrix structure is formed between the two polymers near the surface of the film, suppressing surface roughness. Furthermore, it is assumed that keeping the water content of the F film at 4% by mass or less can suppress the excessive formation of the hydrophilic groups and the interactions, thereby suppressing a decrease in heat resistance due to degradation of the F polymers. This mechanism of action is particularly evident when the F film contains an inorganic filler, improving the retention of the inorganic filler in the F film and suppressing its surface roughness.

[0012] The thickness of the F film is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 25 μm or less. The lower limit of the F film thickness is not particularly limited and can be 1 μm or more. By setting the thickness of the F film within the above numerical range, the F particles, A particles, inorganic filler, etc. can be well dispersed within the F film, the proportion of F particles, A particles, and inorganic filler present on the F film surface can be reduced, and the adhesion to the metal substrate layer when the F film is formed into a laminate described below can be improved.

[0013] In addition to the F polymer and the A polymer, the F film may contain inorganic fillers, various additives, etc. Each component that can be contained in the film will be described below.

[0014] The F film contains an F polymer. One type of F polymer may be used, or two or more types may be used. The F polymer is a polymer containing units (hereinafter also referred to as "TFE units") based on tetrafluoroethylene (hereinafter also referred to as "TFE units"). From the viewpoint of suitably exhibiting the properties due to the TFE units, the content of the TFE units in the F polymer is preferably 50 mol% or more, more preferably 90 mol% or more, based on the total units in the F polymer. The content may be 99 mol% or less, or may be 98 mol% or less.

[0015] From the viewpoints of adhesion to a substrate layer when the F film is formed into a laminate described below, affinity with the A polymer, etc., it is preferable that the F polymer has a carbonyl group-containing group. The carboxyl group-containing group is preferably one or more groups selected from the group consisting of a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a maleimide group, a carbamate group (-OC(O)NH), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.), and a carbonate group (-OC(O)O-), and more preferably one or more groups selected from the group consisting of an acid anhydride group, a carboxyl group, and a maleimide group.

[0016] The number of carbonyl-containing groups in the F polymer is 1 × 10 6The number of carbonyl group-containing groups per unit is preferably 10 to 5000, more preferably 100 to 3000. The number of carbonyl group-containing groups can be quantified based on the composition of the polymer or by the method described in WO 2020 / 145133.

[0017] The carbonyl group-containing group may be contained in a unit derived from a monomer in the F polymer, or may be contained in a terminal group of the main chain of the F polymer, with the former being preferred. Examples of the latter include tetrafluoroethylene-based polymers having a carbonyl group-containing group as a terminal group derived from a polymerization initiator, chain transfer agent, etc., and polymers obtained by subjecting tetrafluoroethylene-based polymers to plasma treatment or ionizing radiation treatment. Preferred monomers having a carbonyl group-containing group include itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"). NAH is more preferred from the viewpoint of adhesion to a substrate layer when the F film is formed into a laminate, as described below.

[0018] The F polymer is preferably polytetrafluoroethylene (PTFE), a polymer (ETFE) comprising TFE units and units based on ethylene, a polymer comprising TFE units and units based on propylene, a polymer (PFA) comprising units based on TFE units and perfluoro(alkyl vinyl ether) (PAVE) (PAVE units) or a polymer (FEP) comprising units based on TFE units and hexafluoropropylene, more preferably PFA or FEP having carbonyl group-containing groups, and even more preferably PFA having carbonyl group-containing groups.These polymers may further comprise units based on other comonomers.

[0019] The F polymer is preferably a polymer having a carbonyl group-containing group containing TFE units and PAVE units, more preferably a polymer containing TFE units, PAVE units, and units based on a monomer having a carbonyl group-containing group, and even more preferably a polymer containing TFE units, PAVE units, and units based on a monomer having a carbonyl group-containing group, in the following order: 90 to 99 mol%, 0.99 to 9.97 mol%, and 0.01 to 3 mol% of the total units. Perfluoro(propyl vinyl ether) (PPVE) is preferred as PAVE. Specific examples of the F polymer include the polymers described in WO 2018 / 016644.

[0020] From the viewpoint of enhancing the above-mentioned mechanism of action, the melting temperature of the F polymer is preferably 250 to 315°C, more preferably 280 to 310°C. From the same viewpoint, the glass transition point of the F polymer is preferably 70 to 150°C. The fluorine content of the F polymer is preferably 70 to 76 mass%. The fluorine content is determined from the polymer composition. An F polymer having a fluorine content within the above-mentioned numerical range has extremely low affinity with other materials, and it is difficult to form a film with excellent surface roughness suppression and heat resistance with other polymers. However, due to the above-mentioned mechanism of action, such a film can be easily obtained according to the present invention.

[0021] From the viewpoint of the smoothness, electrical properties, heat resistance, etc. of the F film, the content of the F polymer relative to the total mass of the F film is preferably 75 to 99 mass%, more preferably 80 to 98 mass%, and even more preferably 85 to 97 mass%.

[0022] The F film contains an A polymer. One type of A polymer may be used, or two or more types may be used. Examples of the A polymer include polyamide resin (hereinafter also referred to as "PA"), polyimide resin (hereinafter also referred to as "PI"), maleimide resin (hereinafter also referred to as "MI"), polyamideimide resin (hereinafter also referred to as "PAI"), polyetherimide resin, polysulfone resin, polyethersulfone resin, polyetherketone resin, polyetheretherketone resin, polyetherketoneketone resin, polyolefin resin, polyacetal resin, polycarbonate resin, polyester resin, polyphenylene sulfide resin, polyphenylene ether resin, poly(meth)acrylate resin, fluororesin, and derivatives thereof. Among the above, from the viewpoints of the adhesion, heat resistance, and affinity with the F polymer, one or more polymers selected from the group consisting of PI, PAI, and MI are preferred.

[0023] From the viewpoint of the adhesion, heat resistance, and affinity with the F polymer, the A polymer preferably has a carbonyl group-containing group. The carbonyl group-containing group is as described above, and will not be described here. The number of carbonyl group-containing groups in the A polymer is 1×10 6 The number per unit is preferably 10 to 5000, more preferably 100 to 3000. The position of the carbonyl group-containing group is not particularly limited, and it is preferable that the carbonyl group be contained in at least one of the side chain and the terminal group of the main chain. In addition, from the viewpoint of improving the UV processability of the F film, the A polymer may have an aromatic group. The weight average molecular weight of the A polymer is preferably 10,000 to 1,000,000.

[0024] From the viewpoint of the above-mentioned adhesion and heat resistance, the content of the A polymer relative to the total mass of the F film is preferably from 1 to 25 mass %, more preferably from 2 to 20 mass %, and even more preferably from 3 to 15 mass %.

[0025] The F film may contain an inorganic filler. Due to the above-mentioned mechanism of action, the F film, even when containing an inorganic filler, has excellent surface roughness suppression and heat resistance, and is likely to highly exhibit the physical properties of the inorganic filler. For example, when an F film containing an inorganic filler is formed into a laminate as described below, the difference in linear expansion coefficient with the substrate layer can be reduced, and adhesion can be improved. Examples of inorganic fillers include nitride fillers and inorganic oxide fillers, and one or more selected from the group consisting of boron nitride filler, beryllium (beryllium oxide), silica filler, and metal oxide (cerium oxide, alumina, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.) fillers are preferred.

[0026] The shape of the inorganic filler is not particularly limited, and may be particulate or non-particulate, such as fibrous or scaly. From the viewpoint of dispersibility in the F film, particulate is preferred. From the viewpoints of surface roughness suppression, adhesion, dispersibility in the F film, etc., the average particle diameter (D50) of the particulate inorganic filler is preferably 0.001 μm to 3 μm, more preferably 0.01 μm to 1 μm. The inorganic filler may also have a microstructure. At least a portion of the surface of the inorganic filler may be coated (surface treated) with a silane coupling agent.

[0027] From the viewpoints of preventing surface roughness and improving adhesion, the content of the inorganic filler relative to the total mass of the F film is preferably 40 to 75 mass%, more preferably 45 to 75 mass%, even more preferably 50 to 75 mass%, and particularly preferably 50 to 65 mass%.

[0028] In addition to the above components, the F film may further contain other components such as surfactants, thixotropy-imparting agents, pH adjusters, pH buffers, viscosity modifiers, antifoaming agents, silane coupling agents, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, flame retardants, and various organic fillers, provided that the effects of the F film are not impaired.

[0029] The F film may be produced by peeling off the substrate layer from a laminate obtained by the laminate production method described below, or may be produced by a method such as extrusion molding, etc. However, the production method of the F film is not limited to these.

[0030] The method for producing a surface-modified film of the present disclosure includes plasma treating the surface of the F film to obtain a surface-modified film. Examples of plasma irradiation devices used in plasma treatment include high-frequency induction, capacitively coupled electrode, corona discharge electrode-plasma jet, parallel plate, remote plasma, atmospheric pressure plasma, and ICP high-density plasma. Gases used in plasma treatment include oxygen gas, nitrogen gas, rare gases (such as argon), hydrogen gas, alcohol gas (such as ethanol), and ammonia gas. Specific examples of gases used in plasma treatment include argon gas, a mixed gas of hydrogen gas and nitrogen gas, a mixed gas of hydrogen gas, nitrogen gas, and argon gas, and a mixed gas of nitrogen gas and ethanol gas. The plasma treatment may be vacuum plasma treatment or atmospheric pressure plasma treatment. Examples of atmospheric pressure plasma treatment include the atmospheric pressure plasma treatment described in JP 2007-284649 A, which uses a mixed gas of nitrogen gas and ethanol gas.

[0031] The laminate of the present disclosure (hereinafter also referred to as "F laminate") comprises a substrate layer and a polymer layer (hereinafter also referred to as "F layer") that contains an F polymer and an A polymer and has a water content of 0.01 to 4 mass %. The F laminate may have two or more F layers, for example, a configuration of F layer / substrate layer / F layer. The F laminate may also have two or more substrate layers, for example, a configuration of substrate layer / F layer / substrate layer.

[0032] The type of substrate layer is not particularly limited, and metal substrate layers, resin substrate layers, etc. can be used. The resin substrate layer can be a film layer containing a resin, and examples of the resin include PI, polyarylate, polysulfone, polyarylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyaryl ether ketone, PAI, liquid crystalline polyester, and liquid crystalline polyesteramide. From the viewpoint of adhesion to the F layer, a film layer containing PI is preferred. The PI content relative to the total mass of the film layer is preferably 70% by mass or more, more preferably 80% by mass or more, and may even be 100% by mass. Examples of metals constituting the metal substrate layer include copper, copper alloys, stainless steel, nickel, nickel alloys (including 42 alloy), aluminum, aluminum alloys, titanium, and titanium alloys. The metal substrate layer is preferably composed of a metal foil layer such as rolled copper foil or electrolytic copper foil. The surface of such a metal foil layer may be subjected to an anti-rust treatment (e.g., an oxide film such as chromate) or a roughening treatment. The metal foil layer may be a carrier-attached metal foil layer consisting of a carrier copper foil (thickness: 10 μm to 35 μm) and an ultrathin copper foil (thickness: 2 μm to 5 μm) laminated on the surface of the carrier copper foil via a release layer. The surface of the metal substrate layer may be treated with a silane coupling agent. In this case, the entire surface of the metal substrate layer may be treated with the silane coupling agent, or only a portion of the surface of the metal substrate layer may be treated with the silane coupling agent.

[0033] When the substrate layer is a metal substrate layer, the thickness of the substrate layer is preferably 2 μm to 40 μm. When the substrate layer is a resin substrate layer, the thickness of the substrate layer is preferably 10 μm to 100 μm. From the viewpoint of adhesion with the F layer, the ten-point average roughness of the surface of the metal substrate layer is preferably 0.01 μm to 1.5 μm.

[0034] The F laminate comprises an F layer containing an F polymer and an A polymer and having a moisture content of 0.01 to 4% by mass. The preferred aspects and contents of the F polymer and the A polymer, as well as the preferred numerical ranges for the moisture content and thickness of the F layer, are the same as those for the F film, and therefore will not be described here. The F layer may contain an inorganic filler and other components. The preferred aspects and contents of the inorganic filler, as well as details of the other components, are the same as those for the F film, and therefore will not be described here. The moisture content of the F layer can be adjusted by any method, including humidifying or drying the laminate, or by adjusting the moisture content of the composition used to form the F layer.

[0035] The F laminate can be produced by the laminate production method described below, although the production method for the F laminate is not limited thereto.

[0036] The method for producing a surface-treated laminate of the present disclosure (hereinafter referred to as the method for producing an F laminate) comprises subjecting the surface of the F polymer layer of the F laminate to plasma treatment to obtain an F laminate having a surface-modified F polymer layer. The method for plasma treatment is the same as the method for producing a surface-treated film, and therefore will not be described here. In addition, the method for producing an F laminate may include placing a composition containing an F polymer, an A polymer, etc. (hereinafter referred to as "F composition") on at least one surface of a substrate layer and heating it to form an F polymer layer on the surface of the substrate layer. The disposition and heating of the F composition may be repeated, and is preferably repeated from the viewpoint of the smoothness of the F polymer layer. The F polymer layer may also be formed on both sides of the substrate layer.

[0037] The preferred aspects and contents of the F polymer and A polymer, as well as the preferred numerical ranges for the water content and thickness of the F layer, are the same as those for the F film, and therefore will not be described here. The F composition may contain an inorganic filler and other components. The preferred aspects and contents of the inorganic filler, as well as details of other components, are the same as those for the F film, and therefore will not be described here. The shape of the F polymer contained in the F composition is not particularly limited, and may be particulate or non-particulate, such as fibrous or scaly. From the viewpoint of the electrical properties (low dielectric constant, etc.) and heat resistance of the F film, a particulate shape is preferred. From the viewpoint of the electrical properties (low dielectric constant, etc.) and heat resistance of the F film, the average particle diameter (D50) of the particulate F polymer (hereinafter also referred to as "F particles") is preferably 0.3 μm to 25 μm, more preferably 1 μm to 10 μm. The composition F may contain a liquid dispersion medium. The liquid dispersion medium may be water or a non-aqueous dispersion medium. Examples of non-aqueous dispersion media include amides, ketones, ester glycols, glycol ethers, and glycol acetates. Among these, amides, ketones, N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone or cyclopentanone, glycol monoalkyl ethers, glycol monoaryl ethers, glycol monoalkyl ether acetates, and glycol monoaryl ether acetates are preferred. The content of the liquid dispersion medium relative to the total mass of the composition F is not particularly limited and may be 30 to 70 mass%.

[0038] The method for disposing the F composition on the substrate layer is not particularly limited, and may be, for example, by coating the F composition. Examples of methods for applying the F composition to the substrate layer include spraying, roll coating, spin coating, gravure coating, microgravure coating, gravure offset coating, knife coating, kiss coating, bar coating, die coating, fountain-meyer bar coating, and slot die coating.

[0039] When the F composition contains a liquid dispersion medium, the heating of the F composition preferably includes maintaining the temperature in a low-temperature range and drying the composition to remove the liquid dispersion medium by evaporation. The temperature of the low-temperature range is not particularly limited, but is preferably 80°C or higher and lower than 180°C, more preferably 120 to 170°C. The temperature of the drying range refers to the temperature of the atmosphere during drying. The maintenance time is preferably 0.1 to 10 minutes, more preferably 0.5 to 5 minutes. The drying of the F composition may be carried out by maintaining the temperature of the drying range in a single stage, or in two or more stages at different temperatures. Examples of methods for maintaining the temperature of the drying range include a method using an oven, a method using a ventilated drying furnace, and a method using heat rays such as infrared rays. The atmosphere during maintenance at the temperature of the drying range may be either normal pressure or reduced pressure. The atmosphere may be an oxidizing gas atmosphere, a reducing gas atmosphere, or an inert gas atmosphere.

[0040] The heating of the F composition preferably includes maintaining the temperature of the baking zone and baking for the purpose of baking the F polymer, etc. The temperature of the baking zone is preferably 250 to 400°C, more preferably 300 to 380°C. The temperature of the baking zone refers to the temperature of the atmosphere during baking. The time for maintaining the temperature of the baking zone is preferably 0.5 to 5 minutes, more preferably 1 to 2 minutes. Examples of methods for maintaining the temperature of the baking zone include a method using an oven, a method using a ventilated drying furnace, and a method of irradiating heat rays such as infrared rays. The baking of the F composition may be performed in one stage by maintaining the temperature of the baking zone, or in two or more stages at different temperatures. To improve the surface smoothness of the F polymer layer, pressure may be applied using a heated plate, heated roll, etc. As a heating method, far-infrared irradiation is preferred because it allows baking in a short time and the far-infrared oven is relatively compact. The heating method may also be a combination of infrared heating and hot air heating. The effective wavelength band of the far infrared rays is preferably 2 μm to 20 μm, more preferably 3 μm to 7 μm, in order to promote uniform fusion of the F polymer. The atmosphere in which heating for the purpose of firing is carried out may be either under normal pressure or under reduced pressure, and may be any of an oxidizing gas atmosphere, a reducing gas atmosphere, and an inert gas atmosphere, with a reducing gas atmosphere or an inert gas atmosphere being preferred from the viewpoint of suppressing oxidative deterioration of the metal substrate layer and the F polymer layer.

[0041] In the method for producing the F laminate, a substrate layer may be further provided on the surface of the F polymer layer formed on one surface of the substrate layer. The method for forming the substrate layer is not particularly limited, and examples include a method of thermocompression bonding the F polymer layer and the substrate layer.

[0042] The uses of the above-mentioned F film and F laminate are not particularly limited, and they can be used, for example, to manufacture printed circuit boards. Examples of methods for manufacturing printed circuit boards include a method of processing the metal substrate layer in the F laminate into a conductor circuit (pattern circuit) of a predetermined pattern by etching or the like, or a method of forming a pattern circuit on the F film by electroplating (semi-additive method (SAP method), modified semi-additive method (MSAP method), etc.). [Example]

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to examples, but the embodiments of the present disclosure are not limited to these.

[0044] 1. Preparation of each component for manufacturing the laminate [F Polymer] F polymer: containing 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE units, NAH units, and PPVE units in this order, and having a carbonyl group-containing group with a main chain carbon number of 1×10 6 Polymer with 1000 particles per particle (melting temperature: 300℃), particulate (D50: 2.1μm). [Polymer A] A polymer: A polyamide-imide resin having a carboxyl group at the terminal. [Inorganic filler] Inorganic filler: Silane coupling agent treated silica particles, D50: 0.6 μm [Board Layer] Substrate layer: Polyimide resin film, thickness 25 μm [Metal foil] Metal foil: Copper foil with a ten-point average roughness of 0.4 μm, thickness 18 μm

[0045] 2. Manufacturing of laminates <Example 1> A composition containing 24 parts by mass of F polymer, 1 part by mass of A polymer, 25 parts by mass of inorganic filler, and 50 parts by mass of water was applied to one surface of the substrate layer and dried to form a coating. The coating was then further heated to bake the F polymer and polymers other than the F polymer, forming a 10 μm thick F layer and obtaining a laminate. The moisture content of the F layer was measured and found to be 0.1% by mass.

[0046] <Example 2 and Example 3> A laminate was produced in the same manner as in Example 1, except that the firing conditions were adjusted so that the water absorption rate of the F layer was set to the values ​​shown in Table 1.

[0047] 3. Evaluation <<Evaluation of surface roughness suppression>> Plasma treatment (introduced gas: hydrogen gas) was performed on the surface of the F layer of the laminate obtained in Examples 1 to 3. The surface of the F layer after the plasma treatment was visually observed and evaluated based on the following evaluation criteria. The results are summarized in Table 1. (Evaluation criteria) A: No surface roughness of the F layer due to sliding of the inorganic filler was observed. B: Surface roughness of the F layer due to sliding of inorganic filler was observed.

[0048] <<Heat resistance evaluation>> Plasma treatment (introduced gas: hydrogen gas) was performed on the surface of the F layer of the laminate obtained in Examples 1 to 3. After the plasma treatment of the laminate, a metal foil was thermocompression bonded to the surface of the F layer to obtain a laminate including the metal foil, the F layer, and the substrate layer. The laminate was subjected to a solder heat resistance test in which it was floated 100 times in a solder bath at 300°C for 30 seconds. After the test, the laminate was visually observed and evaluated based on the following evaluation criteria. The results are summarized in Table 1. (Evaluation criteria) A: Neither the phenomenon of the interface between the F layer and the substrate layer swelling (swelling phenomenon) nor the phenomenon of the metal foil floating from the F layer (floating phenomenon) was observed. B: At least one of the swelling phenomenon and the lifting phenomenon was observed.

[0049] [Table 1]

Claims

1. A film containing a tetrafluoroethylene-based polymer having a carbonyl group-containing group and a melting temperature of 260 to 320°C, and one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins, and having a water content of 0.01 to 4 mass%.

2. The film described in claim 1, wherein one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins have a carbonyl group-containing group.

3. 3. The film according to claim 1, wherein the carbonyl group-containing group is one or more groups selected from the group consisting of an acid anhydride group, a carboxyl group, and a maleimide group.

4. The film according to any one of claims 1 to 3, wherein the content of the tetrafluoroethylene-based polymer relative to the total mass of the film is 75 to 99 mass%.

5. The film according to any one of claims 1 to 4, further comprising an inorganic filler.

6. A method for producing a surface-modified film, comprising plasma-treating the surface of the film according to any one of claims 1 to 5 to obtain a surface-modified film.

7. A laminate comprising a substrate layer and a polymer layer containing a tetrafluoroethylene-based polymer having a carbonyl group-containing group and a melting temperature of 260 to 320°C, and one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins, and having a water content of 0.01 to 4 mass%.

8. A laminate as described in claim 7, wherein one or more polymers selected from the group consisting of polyimide resins, polyamideimide resins, and maleimide resins have a carbonyl group-containing group.

9. 9. The laminate according to claim 7, wherein the carbonyl group-containing group is one or more groups selected from the group consisting of an acid anhydride group, a carboxyl group, and a maleimide group.

10. The laminate according to any one of claims 7 to 9, wherein the content of the tetrafluoroethylene-based polymer relative to the total mass of the polymer layer is 75 to 99 mass%.

11. The laminate according to any one of claims 7 to 10, further comprising an inorganic filler.

12. The laminate according to any one of claims 7 to 11, wherein the substrate layer is a metal substrate layer or a film layer containing a polyimide resin.

13. A method for producing a surface-modified laminate, comprising plasma-treating a surface of the polymer layer of the laminate according to any one of claims 7 to 12, to obtain a laminate having a surface-modified polymer layer.

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