Laminate and method for forming laminate

Abstract

To provide a laminate having excellent adhesiveness between a copper-containing base material and a perfluoropolymer film, and also to provide a method for forming the laminate having excellent adhesiveness.SOLUTION: Provided is a laminate comprising a copper-containing base material and a perfluoropolymer-containing film, wherein the adhesive strength between the base material and the film is 0.2 N / mm or more, and the film has a surface roughness of less than 15 μm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a laminate and a method for forming the laminate.

Background Art

[0002] Generally, perfluoropolymers are widely used as coating materials for metal substrates, taking advantage of the excellent insulating properties, heat resistance, chemical resistance, flame retardancy, etc. of fluororesins.

[0003] For example, Patent Document 1 describes an insulated wire used for a motor coil, in which an insulating layer made of a fluororesin is provided on a copper conductor by extrusion coating.

[0004] Also known is a bus bar in which a powder coating made of a thermosetting resin such as an epoxy resin is electrostatically applied on a copper conductor to form an insulating layer (Patent Document 2, etc.).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present disclosure is to provide a laminate having excellent adhesion between a base material containing copper and a perfluoropolymer film. Another object of the present disclosure is to provide a method for forming a laminate having excellent adhesion as described above.

Means for Solving the Problems

[0007] The present disclosure includes a base material containing copper and a film containing a perfluoropolymer. The laminate is characterized in that the adhesion strength between the base material and the film is 0.2 N / mm or more, and the surface roughness of the film is less than 15 μm.

[0008] It is preferable that the perfluoropolymer is a copolymer containing at least one selected from the group consisting of tetrafluoroethylene (TFE) units, perfluoroalkyl vinyl ether (PAVE) units, and hexafluoropropylene (HFP) units. It is preferable that the perfluoropolymer is a TFE / HFP copolymer. It is preferable that the adhesion strength between the base material and the film is 0.2 N / mm or more and 1.2 N / mm or less, and the surface roughness of the film is 0.1 μm or more and less than 1.5 μm.

[0009] The present disclosure is directed to a method for forming a laminate, comprising applying a primer composition onto a base material containing copper, then applying a powder composition containing a perfluoropolymer by electrostatic coating, and heating to a temperature equal to or higher than the melting point of the perfluoropolymer to form a film. In the method for forming the laminate described above, it is preferable to heat to a temperature equal to or higher than the melting point of the perfluoropolymer to form a film under an oxygen-free atmosphere. Further, in the method for forming the laminate described above, a powder composition containing a perfluoropolymer having a melting point of less than 310 °C is applied by electrostatic coating, and it is preferable to heat to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320 °C to form a film under an oxygen-free atmosphere.

[0010] The present disclosure is directed to a method for forming a laminate, comprising applying a powder composition containing a perfluoropolymer having a melting point of less than 310 °C onto a base material containing copper by electrostatic coating, and heating to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320 °C to form a film. This is also a method for forming a laminate. In the method for forming the laminate, it is preferable to form a film by heating under an oxygen-free condition at a temperature equal to or higher than the melting point of the perfluoropolymer and lower than 320°C.

[0011] This disclosure is about applying a powder composition containing a perfluoropolymer onto a substrate containing copper by electrostatic coating, and forming a film by heating under an oxygen-free condition at a temperature equal to or higher than the melting point of the perfluoropolymer. This is also a method for forming a laminate.

[0012] As described above, among the methods for forming the laminate described above, it is preferable to use two or more of them in combination.

[0013] In the method for forming the laminate, the perfluoropolymer is preferably a copolymer containing tetrafluoroethylene (TFE) units and at least one selected from the group consisting of perfluoroalkyl vinyl ether (PAVE) units and hexafluoropropylene (HFP) units.

[0014] In the method for forming the laminate, the primer composition preferably contains a perfluoropolymer as an essential component and further contains one or more resins selected from the group consisting of polyamideimide, polyethersulfone, and polyarylene sulfide.

[0015] This disclosure is also about a laminate formed by the method for forming any of the above laminates. In the laminate formed by the method for forming any of the above laminates, the perfluoropolymer is preferably a TFE / HFP copolymer. This disclosure is also about an article having the laminate described above. This disclosure is also about a magnet wire having the laminate described above. This disclosure is also about a bus bar having the laminate described above. This disclosure is also about a high-frequency substrate having the laminate described above.

Advantages of the Invention

[0016] The laminate of the present disclosure has excellent adhesion between a base material containing copper and a perfluoropolymer film. In addition, the method for forming the laminate of the present disclosure can provide a laminate having excellent adhesion between a base material containing copper and a perfluoropolymer film.

Brief Description of the Drawings

[0017]

Figure 1

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present disclosure will be described in detail. A laminate formed by forming a perfluoropolymer film having excellent insulation properties on a base material such as copper or a copper alloy is expected to be used for magnet wires, bus bars, high-frequency substrates, and the like.

[0019] As a method for forming the above laminate, a method of forming a film made of an extrusion composition containing a perfluoropolymer on a long copper base material is known. However, in such a laminate, the adhesion between the base material and the film is not sufficient, and when bending, problems such as peeling and cracking of the film and uneven film thickness remain as issues.

[0020] On the other hand, a method of forming a perfluoropolymer film on the surface of a copper base material by electrostatic coating using a powder composition containing a perfluoropolymer can be considered. Such powder coating is advantageous in that it can form a good film on a base material having a complex shape compared to extrusion coating. However, it has been difficult to ensure sufficient adhesion between the copper base material and the perfluoropolymer film.

[0021] The present disclosure can provide a laminate excellent in adhesiveness by forming a laminate having a perfluoropolymer film on a copper-containing substrate by at least one or more of the following methods (1) to (3). Furthermore, the laminate of the present disclosure is also excellent in surface smoothness. (1) A primer composition is applied onto a copper-containing substrate, and then a powder composition containing a perfluoropolymer is applied by electrostatic coating, and heated to a temperature equal to or higher than the melting point of the perfluoropolymer to form a film. (2) A powder composition containing a perfluoropolymer having a melting point of less than 310°C is applied onto a copper-containing substrate by electrostatic coating, and heated to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320°C to form a film. (3) A powder composition containing a perfluoropolymer is applied onto a copper-containing substrate by electrostatic coating, and heated to a temperature equal to or higher than the melting point of the perfluoropolymer in an oxygen-free atmosphere to form a film.

[0022] By the method for forming a laminate as described above, a laminate having an adhesion strength between the copper-containing substrate and the film of 0.2 N / mm or more and a surface roughness of the film of less than 15 μm can be obtained. When such a laminate is applied to a magnet wire, a bus bar, a high-frequency substrate, etc. having a copper-containing conductor as a substrate, it exhibits particularly excellent performance.

[0023] (Laminate) The laminate of the present disclosure includes a copper-containing substrate and a film containing a perfluoropolymer, the adhesion strength between the substrate and the film is 0.2 N / mm or more, and the surface roughness of the film is less than 15 μm.

[0024] In the laminate of the present disclosure, the adhesion strength between the substrate and the film is 0.2 N / mm or more. When the adhesion strength is 0.2 N / mm or more, peeling or cracking of the film does not occur during bending, and problems such as non-uniform film thickness do not occur. The adhesion strength between the substrate and the film is preferably 0.3 N / mm or more, more preferably 0.4 N / mm or more. The upper limit of the adhesion strength is not particularly limited, but 1.2 N / mm or less is sufficient, and even 1.0 N / mm or less can sufficiently exhibit the effects required in the present disclosure. In this specification, the adhesion strength is a value obtained by the method for measuring the adhesion strength in the following examples.

[0025] Note that when the adhesion strength is as described above, such as in the method for forming the laminate according to (1) above, after applying a primer film to the substrate surface in advance and then providing a film composed of a powder composition containing a perfluoropolymer, it means the adhesion strength between the substrate and the primer film.

[0026] The surface roughness of the film is preferably less than 1.5 μm. When the surface roughness is less than 1.5 μm, it is advantageous in that good electrical characteristics can be exhibited. The surface roughness of the film is preferably 1.0 μm or less, more preferably 0.7 μm or less. The lower limit of the surface roughness is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more. In this specification, the surface roughness is a value obtained by the method for measuring the surface roughness in the following examples. To make the surface roughness of the film less than 1.5 μm, for example, it can be achieved by heating at a temperature 20°C or more higher than the melting point of the perfluoropolymer for 20 minutes or more.

[0027] (Substrate) The substrate used in the laminate of the present disclosure contains copper, and examples thereof include copper metal alone and copper alloys. For example, as copper metal alone, tough pitch copper, oxygen-free copper, etc. can be mentioned. In addition, composite copper composed of trace components such as aluminum, nickel, silver, etc., and clad materials of copper and aluminum can be mentioned. The substrate used in the laminate of the present disclosure is preferably copper metal alone.

[0028] The above base material may be subjected to surface treatment such as cleaning and sandblasting as required. When the base material is surface-treated to roughen it, the anchor effect with the powder composition used during film formation increases, and the adhesion to the film is further improved.

[0029] (Perfluoropolymer) The perfluoropolymer contained in the film of the laminate of the present disclosure is not particularly limited, and any known one can be used. The above perfluoropolymer can be obtained, for example, by polymerizing one or more perfluoro monomers such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE) as monomer components.

[0030] The above PAVE is not particularly limited, and examples include one or more of perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), perfluoropropyl vinyl ether (PPVE), etc. In particular, perfluoropropyl vinyl ether (PPVE) is preferred.

[0031] The perfluoropolymer is preferably a copolymer containing a tetrafluoroethylene unit as an essential component and at least one selected from the group consisting of perfluoroalkyl vinyl ether units and hexafluoropropylene units. Also, two or more of these copolymers may be used in combination.

[0032] Specifically, TFE / PAVE copolymers (PFA), TFE / HFP copolymers (FEP), TFE / PAVE / HFP copolymers, etc. are preferred. In particular, TFE / HFP copolymers and TFE / PAVE / HFP copolymers are suitable because they can form films at relatively low temperatures.

[0033] The melting point of the above perfluoropolymer is preferably less than 310°C. More preferably, the melting point is 200°C or higher and less than 310°C, and even more preferably 220°C or higher and 270°C or lower. If the melting point is within the above range, a smooth surface can be obtained without a decrease in heat resistance. In this specification, the melting point is the temperature corresponding to the maximum value in the melting heat curve when the temperature is raised at a rate of 10°C / min using a differential scanning calorimeter [DSC].

[0034] The MFR of the above perfluoropolymer is preferably 1 to 40 g / 10 min. If it is within the above range of the melt flow rate, the interlayer adhesion is good. Also, the fluidity during coating is good and the surface smoothness is high. Further, it is not necessary to heat for a long time to obtain the desired smoothness of the film, and the deterioration of the perfluoropolymer does not become a problem. A more preferable lower limit is 5 g / 10 min, and a more preferable upper limit is 30 g / 10 min.

[0035] In this specification, the above MFR is a value measured according to ASTM D2116 at a temperature of 372°C and a load of 5 kg. The above perfluoropolymer can have an MFR within the above range by adjusting the molecular weight or the like.

[0036] The method for producing the above perfluoropolymer is not particularly limited, and for example, it can be obtained by copolymerizing using a conventionally known polymerization method such as emulsion polymerization or suspension polymerization.

[0037] In addition to the perfluoropolymer, the above film may contain a heat stabilizer, a coloring pigment additive, etc. described later. In the above film, it is preferable that the perfluoropolymer is contained in an amount of 70 to 100% by mass. If the content of the perfluoropolymer is within the above range, it is advantageous in that good electrical characteristics can be exhibited. A more preferable lower limit is 90% by mass, and an even more preferable lower limit is 95% by mass.

[0038] In the laminate of the present disclosure, the film thickness of the film is preferably 10 to 200 μm, more preferably 20 μm or more, even more preferably 30 μm or more, more preferably 150 μm or less, and even more preferably 100 μm or less. If the film thickness is too thick, it may be difficult to miniaturize the device when used in devices such as motors. Also, if the film thickness is too thin, sufficient insulation may not be obtained.

[0039] Also, the relative permittivity of the above film is preferably 2.1 to 2.8, and more preferably 2.6 μm or less. By setting it within such a range, it is advantageous in that good insulation can be exhibited. In this specification, the relative permittivity is a value obtained by the method for measuring the relative permittivity in the following examples.

[0040] (Method for forming a laminate) For forming the laminate of the present disclosure, it is preferable to use a powder composition containing the above perfluoropolymer, coat it on a substrate by an electrostatic coating method, and heat it to form a film.

[0041] (Powder composition) In the present disclosure, the powder composition used for film formation contains the powder of the above perfluoropolymer.

[0042] The above powder composition preferably has an average particle diameter of 1 to 100 μm. If it is less than 1 μm, electrostatic repulsion is likely to occur during coating, and film formation tends to be difficult. If it exceeds 100 μm, the smoothness of the resulting film may deteriorate. A more preferable lower limit is 10 μm, and a more preferable upper limit is 80 μm.

[0043] The average particle size of the powder composition can be within the above range by adjusting the conditions of grinding and classification in the method for producing the powder composition described below. In this specification, the above average particle size is a value measured by the laser diffraction method. Specifically, it is the volume-based median diameter measured by MT-3300II manufactured by Microtrac.

[0044] The above powder composition preferably has an apparent density of 0.5 to 1.1 g / ml. If it is less than 0.5 g / ml, foaming may occur during coating or the number of coating times may increase, making electrostatic coating difficult. If it exceeds 1.1 g / ml, it tends to be difficult to industrially produce such a powder composition. The lower limit of the preferred apparent density is 0.7 g / ml, and the more preferred upper limit is 1.0 g / ml. In this specification, the above apparent density g / ml is a value obtained by measurement in accordance with JIS K 6891.

[0045] The above powder composition may contain a heat stabilizer. When the powder composition contains the above heat stabilizer, it is possible to prevent coloring and foaming of the coating film that may occur due to the instability of the perfluoropolymer when heated at a temperature above the melting point. As the above heat stabilizer, from the viewpoint of preventing the oxidation of the above perfluoropolymer, it is preferably at least one selected from the group consisting of amine-based antioxidants, organic sulfur-containing compounds, and metal powders.

[0046] Examples of the amine-based antioxidant include aromatic amines having an aromatic hydrocarbon group such as a phenyl group or a naphthyl group in the molecule, such as phenylenediamine compounds such as N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and reaction products of diphenylamine and diisobutylene; and other aromatic secondary amine compounds such as dinaphthylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine, phenylcyclohexyl-p-phenylenediamine, and styrenated diphenylamine.

[0047] Examples of the organic sulfur-containing compound include mercaptobenzimidazole-based compounds such as 2-mercaptobenzimidazole and 2-mercaptomethylbenzimidazole; mercaptobenzothiazole-based compounds such as 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, 2-(4'-morpholinodithio)benzothiazole, N-cyclohexyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, and N-tert-butyl-2-benzothiazolylsulfenamide; mercaptoimidazoline-based compounds such as 2-mercaptoimidazoline; and dithiocarbamic acids such as pentamethylenedithiocarbamic acid, pipecolyldithiocarbamic acid, dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dibutyldithiocarbamic acid, and N-ethyl-N-phenyldithiocarbamic acid. These may be, for example, metal salts such as Zn, Sn, Cd, Cu, and Fe; or organic salts such as piperidine salts and pipecolyl salts.

[0048] Examples of the organic sulfur-containing compound include thiuram compounds such as thiuram monosulfide like tetramethylthiuram monosulfide; thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabutylthiuram disulfide; and other thiuram compounds such as dipentamethylenethiuram tetrasulfide. Examples of the organic sulfur-containing compound may also include thiourea derivatives such as N,N'-diethylthiourea, dibutylthiourea, and dilaurylthiourea.

[0049] Examples of the metal powder include one or more of cobalt powder, iron powder, zinc powder, tin powder, or copper powder. It is preferable to use the metal powder in combination with the organic sulfur-containing compound and / or the amine-based antioxidant rather than using it alone.

[0050] Among the above heat stabilizers, aromatic ring-containing compounds are preferable, and aromatic amines, mercaptobenzothiazole-based compounds, and mercaptobenzimidazole-based compounds are more preferable, from the viewpoint that stability at a temperature equal to or higher than the melting point of the perfluoropolymer contained in the powder composition, for example, at a high temperature of about 250°C or higher, is required. When the powder composition is used for applications such as semiconductor manufacturing equipment, a non-metallic compound that does not leave metal residues is preferable as the above heat stabilizer.

[0051] The above heat stabilizer can be produced by a conventionally known method, but usually, commercially available products can be used.

[0052] The above heat stabilizer is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the perfluoropolymer. If it is less than 0.001 part by mass, the thermal stability of the perfluoropolymer may deteriorate, and if it exceeds 5 parts by mass, coloring may occur in the resulting film and foaming may occur due to decomposition of the heat stabilizer, which is not preferable. More preferably, it is 0.003 to 2 parts by mass.

[0053] The above powder composition may contain a coloring pigment. Examples of the coloring pigment include titanium oxide, cobalt oxide, carbon, chromium oxide, iron oxide, mica, and the like. The above coloring pigment is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the above TFE-based copolymer. If it is less than 0.001 part by mass, the desired coloring may not be obtained, and if it exceeds 5 parts by mass, foaming may occur in the resulting film. More preferably, it is 0.003 to 2 parts by mass.

[0054] The above powder composition may be used in combination with the above perfluoropolymer and, if desired, the above stabilizer and / or coloring pigment, and may contain additives, etc. as necessary. The above additives, etc. are not particularly limited, and examples include those used in general powder compositions. Examples of the above additives, etc. include other pigments such as rust-preventing pigments and baking pigments for the purpose of rust prevention, etc.; coating film reinforcing materials such as carbon fibers, glass fibers, glass flakes, mica, etc. for the purpose of preventing shrinkage of the coating film; conductivity-imparting materials such as conductive carbon for the purpose of imparting conductivity, etc., and may also be leveling agents, antistatic agents, etc.

[0055] The content of the above additive is preferably 0 to 10.0% by mass, more preferably 0 to 5.0% by mass, based on the above powder composition.

[0056] The average particle diameter of the above heat stabilizer, coloring pigment, and additive is preferably 0.1 to 70 μm, more preferably 0.1 to 50 μm. If the particle diameters are within this range, they can be uniformly dispersed in the composition and stably applied. These average particle diameters are values measured by the laser diffraction method. Specifically, it is the volume-based median diameter measured by MT-3300II manufactured by Microtrac.

[0057] The powder composition used in the present disclosure can be produced by mixing the above-described components. Using various grinders such as jet mills, hammer mills, and pin mills, and appropriately combining them as necessary, and adjusting the grinding conditions, grinding time, and blending of the resin components used in combination, etc., appropriate comminution can be performed.

[0058] The method for forming the laminate of the present disclosure is preferably to form a laminate including a copper base material and a perfluoropolymer film by at least one or more of the following (1) to (3). By forming the laminate by such a method, the adhesiveness and surface smoothness can be improved. (1) A primer composition is applied onto a base material containing copper, and then the above powder composition is applied by electrostatic coating and heated to a temperature equal to or higher than the melting point of the perfluoropolymer to form a film. (2) The above powder composition containing a perfluoropolymer having a melting point of less than 310°C is applied onto a base material containing copper by electrostatic coating and heated to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320°C to form a film. (3) The above powder composition is applied onto a base material containing copper by electrostatic coating and heated to a temperature equal to or higher than the melting point of the perfluoropolymer under an oxygen-free condition to form a film.

[0059] The method of (1) above forms a primer film on the base material in advance. When forming a perfluoropolymer film on a base material containing copper, providing a primer layer first is preferable in that the adhesiveness between the perfluoropolymer layer and the base material can be further enhanced.

[0060] (Primer composition) The primer composition used in the method of (1) above is preferably the same as the above perfluoropolymer that forms a film. That is, it is preferably a copolymer containing a tetrafluoroethylene unit and at least one selected from the group consisting of a perfluoroalkyl vinyl ether unit and a hexafluoropropylene unit. Specifically, a TFE / PAVE copolymer (PFA), a TFE / HFP copolymer (FEP), a TFE / PAVE / HFP copolymer, etc. are preferable.

[0061] The primer composition preferably further uses at least one resin selected from the group consisting of polyamideimide (PAI), polyethersulfone (PES), and polyarylene sulfide (PAS), which are heat-resistant resins.

[0062] (Polyamideimide) PAI is a resin composed of a polymer having an amide bond and an imide bond in its molecular structure. The above PAI is not particularly limited. For example, the reaction of an aromatic diamine having an amide bond in the molecule with an aromatic tetracarboxylic acid such as pyromellitic acid; the reaction of an aromatic tricarboxylic acid such as trimellitic anhydride with a diamine such as 4,4-diaminodiphenyl ether or a diisocyanate such as diphenylmethane diisocyanate; resins composed of high molecular weight polymers obtained by reactions such as the reaction of a dibasic acid having an aromatic imide ring in the molecule with a diamine, etc. can be mentioned. As the above PAI, those composed of a polymer having an aromatic ring in the main chain are preferable from the viewpoint of excellent heat resistance.

[0063] PAI preferably has a glass transition temperature of 200°C or higher. More preferably, it is 250°C or higher. By having a glass transition temperature in the above range, the heat resistance of the primer composition can be improved. Also, the glass transition temperature of PAS is preferably 320°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower. The above glass transition temperature is measured by a differential scanning calorimetry (DSC) apparatus.

[0064] PAI preferably has a melting point of 250°C or higher. More preferably, it is 260°C or higher. By having a melting point in the above range, the heat resistance of the resin composition can be improved. Also, the melting point of PAI is preferably 320°C or lower, more preferably 300°C or lower. The above melting point is measured by a differential scanning calorimetry (DSC) apparatus.

[0065] (Polyethersulfone) The above PES has excellent adhesion to the object to be coated, has sufficient heat resistance even at the temperature during baking when forming the above coating film, and the obtained coating film is excellent in corrosion resistance and water vapor resistance.

[0066] PES is, for example, the following general formula:

[0067] [Chemical formula] It is a resin composed of a polymer having a repeating unit represented by

[0068] PES is not particularly limited, and examples thereof include resins composed of polymers obtained by polycondensation of dichlorodiphenyl sulfone and bisphenol.

[0069] PES preferably has a glass transition temperature of 200 °C or higher. More preferably, it is 205 °C or higher, and still more preferably, it is 210 °C or higher. By having a glass transition temperature within the above range, the heat resistance of the primer composition can be improved. Also, the glass transition temperature of PES is preferably 250 °C or lower, and more preferably 240 °C or lower. The above glass transition temperature is measured by a differential scanning calorimetry (DSC) apparatus.

[0070] (Polyarylene sulfide) As PAS, for example, the following general formula: -(Ar-S)- (In the formula, Ar represents an arylene group, and S represents sulfur), and those having a repeating unit represented by the formula are exemplified. The content ratio of the repeating unit in the resin is preferably 70 mol% or more. Examples of the arylene group include p-phenylene, m-phenylene, o-phenylene, alkyl-substituted phenylene, phenyl-substituted phenylene, halogen-substituted phenylene, amino-substituted phenylene, amide-substituted phenylene, p,p'-diphenylene sulfone, p,p'-biphenylene, p,p'-biphenylene ether, and the like. PAS can be roughly classified into a resin having a crosslinked or branched structure (crosslinked type) and a resin having substantially no crosslinked or branched structure (linear type). In the present disclosure, either the crosslinked type or the linear type can be used without problems. As PAS, for example, polyphenylene sulfide is preferably exemplified.

[0071] PAS preferably has a glass transition temperature of 70°C or higher. More preferably, it is 80°C or higher, and even more preferably, it is 85°C or higher. By having a glass transition temperature within the above range, the heat resistance of the resin composition can be improved. Also, the glass transition temperature of PAS is preferably 300°C or lower, and more preferably 250°C or lower. The above glass transition temperature is measured by a differential scanning calorimetry (DSC) apparatus.

[0072] PAS preferably has a melting point of 180°C or higher. More preferably, it is 190°C or higher. By having a melting point within the above range, the heat resistance of the resin composition can be improved. Also, the melting point of PAS is preferably 380°C or lower, and more preferably 350°C or lower. The above melting point is measured by a differential scanning calorimetry (DSC) apparatus.

[0073] Since the above resin has excellent adhesion to the substrate and can form a coating film with excellent non-stickiness, it is preferably PES or PAS, and more preferably PAS. PES and PAS may each consist of one type or two or more types.

[0074] The above resin is preferably PES or PAS and PAI. That is, the above resin may be a mixture of PAS and PAI, or a mixture of PES and PAI. When the above resin contains PAI in addition to PAS or PES, a coating film excellent in secondary adhesion (adhesion to the substrate after repeatedly heating and cooling the coating film) can be obtained. It is more preferable that the above resin is PAS and PAI, that is, a mixture of PAS and PAI. PAS, PES, and PAI may each consist of one or more than two kinds.

[0075] When the above resin is PAS or PES and PAI, the above PAS or PES is preferably 20 to 80% by mass of the total amount of the PAS or PES and PAI. More preferably, it is 30 to 70% by mass.

[0076] In the above composition, the mass ratio of the perfluoropolymer to the resin (perfluoropolymer / resin) is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 to 90 / 10, and even more preferably 50 / 50 to 85 / 15. When the mass ratio of the fluororesin to the heat-resistant resin is within the above range, the adhesive force between the perfluoropolymer layer and the primer layer and the adhesive force between the primer layer and the substrate can be increased respectively.

[0077] The above primer composition may appropriately contain other additives. The above primer composition is preferably a powder composition. Similar to the film formation of the perfluoropolymer, it is preferably applied by electrostatic coating and heated to form a film to form a primer layer. In the formation of the primer layer, it is also preferably by the method of (2) and / or (3) above.

[0078] The film thickness of the primer film is preferably 10 to 100 μm, more preferably 20 to 80 μm. If the film thickness of the primer film is within the above range, it is advantageous in that good adhesion can be exhibited between the perfluoropolymer layer and the substrate.

[0079] The above powder composition can be applied onto the primer film by electrostatic coating and then heated and baked to form a film. The electrostatic coating is not particularly limited and may be carried out by a conventional method.

[0080] The heating temperature is preferably set to a temperature equal to or higher than the melting point of the perfluoropolymer. Specifically, it is preferably the melting point + 20°C or higher. The upper limit of the heating temperature may be less than 320°C from the viewpoint of suppressing oxidation of the substrate and deterioration of the film. The heating time is preferably 5 minutes or more, more preferably 10 minutes or more. The upper limit of the heating time may be 60 minutes or less from the viewpoint of suppressing oxidation of the substrate and deterioration of the film.

[0081] As described above, the method of (2) is to apply the above powder composition containing a perfluoropolymer having a melting point of less than 310°C onto a substrate by electrostatic coating and heat it to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320°C to form a film.

[0082] When forming a film made of a powder composition containing a perfluoropolymer on the surface of a substrate containing copper, if the powder composition is heated in a temperature range of 320°C or higher, the oxidation of copper tends to progress. As a result, the adhesion between the copper substrate and the perfluoropolymer film may be impaired. Therefore, in the method of (2), by heating at a temperature of less than 320°C, the oxidation of copper is suppressed and the adhesion between the copper substrate and the perfluoropolymer film is improved. The heating temperature is preferably less than 300°C.

[0083] In the method of (3) above, the powder composition is applied by electrostatic coating and heated under oxygen-free conditions to a temperature equal to or higher than the melting point of the perfluoropolymer. By performing the heating under oxygen-free conditions, oxidation of the substrate can be suppressed, and formation of a fragile oxide layer can be suppressed, so that the adhesiveness to the substrate becomes good.

[0084] As a method of performing heating under oxygen-free conditions, it can be carried out in an inert gas containing at most 1% by mass of oxygen gas. Examples of the inert gas include nitrogen gas and the like.

[0085] In the method of (3) above, it is preferable that the heating temperature and heating time are the same as those in the method of (1) above.

[0086] Among the methods of (1) to (3) above, it is particularly preferable to use the methods of (1), (2), and (3) in combination. Also, it is preferable to use the methods of (1) and (3) in combination, or the methods of (2) and (3) in combination. By using these two methods in combination, formation of the oxide film can be suppressed, and by applying the primer composition, good adhesiveness to the copper substrate can be exhibited.

[0087] By the method for forming a laminate as described above, a laminate excellent in adhesiveness and surface smoothness can be obtained. The present disclosure is also a method for forming a laminate, which is characterized in that a primer composition is applied onto a substrate containing copper, then the above powder composition containing a perfluoropolymer is applied by electrostatic coating, and heated to a temperature equal to or higher than the melting point of the perfluoropolymer to form a film.

[0088] The present disclosure is also a method for forming a laminate, which is characterized in that the above powder composition containing a perfluoropolymer having a melting point of less than 310°C is applied by electrostatic coating onto a substrate containing copper, and heated to a temperature equal to or higher than the melting point of the perfluoropolymer and less than 320°C to form a film.

[0089] The present disclosure is also a method for forming a laminate, which comprises coating the above powder composition on a base material containing copper by electrostatic coating and heating it to a temperature equal to or higher than the melting point of the perfluoropolymer under an oxygen-free atmosphere to form a film.

[0090] By using these methods (1) to (3) alone or in combination of two or more, a laminate excellent in adhesiveness and surface smoothness can be obtained. Among the methods (1) to (3), it is preferable to use two or more in combination. Specifically, as described above, it is preferable to use the methods (1) and (3) in combination, or the methods (2) and (3) in combination, and it is particularly preferable to use the methods (1), (2) and (3) in combination.

[0091] The present disclosure is also an article having the above laminate. Specifically, the laminate of the present disclosure is suitably used for articles such as magnet wires, bus bars, high-frequency substrates, etc. As these conductors, copper or copper alloys are usually used, and the laminate of the present disclosure is suitably used.

[0092] The present disclosure is also a magnet wire having the laminate of the present disclosure. Magnet wires are used for coils of motors and transformers. Examples of motors include motors for electric vehicles, compressor motors for air conditioners and refrigerators, and hermetic motors.

[0093] The present disclosure is also a bus bar having the laminate of the present disclosure. Bus bars are used as wiring members for transmitting current in electric vehicles and in power conversion devices such as inverters and converters. In addition, bus bars are used in switchboards (cubicles), control panels, batteries, etc., and conduct large-capacity currents. Since the bus bar has low electrical resistance, it has the characteristic of being able to efficiently supply a large-capacity current to each part. In addition, since the wiring work is completed simply by fixing the bus bar with screws, it is possible to relatively easily branch a large-capacity power supply throughout the panel even in a large-sized distribution board or control panel. Taking advantage of such characteristics, bus bars are widely used in place of cables and conducting wires. For example, in a battery module equipped with a plurality of batteries, the terminals of one battery and the terminals of another battery are electrically connected via a bus bar.

[0094] The laminate of the present disclosure is suitably used as a circuit board. A circuit board is a plate-shaped component for electrically connecting electronic components such as semiconductors and capacitor chips and at the same time arranging and fixing them in a limited space. The configuration of the circuit board formed from the laminate of the present disclosure is not particularly limited. The circuit board may be any of a rigid board, a flexible board, and a rigid-flexible board. The circuit board may be any of a single-sided board, a double-sided board, and a multilayer board (such as a build-up board). In particular, it can be suitably used for flexible boards and rigid boards. In particular, it can be suitably used as a high-frequency board for 10 GHz or higher. The present disclosure is also a high-frequency board having the laminate of the present disclosure.

[0095] In the present disclosure, the high-frequency circuit includes not only a circuit that simply transmits only high-frequency signals, but also a transmission path that converts a high-frequency signal into a low-frequency signal and outputs the generated low-frequency signal to the outside, and a transmission path that supplies a power supply for driving high-frequency compatible components. Also included are circuits in which transmission paths for transmitting signals that are not high-frequency signals are provided side by side on the same plane. The high-frequency board of the present disclosure can be suitably used for mobile communication terminals such as mobile phones, smartphones, and tablet terminals, communication devices such as Wi-Fi devices, surface acoustic wave (SAW) devices, and radar components. It can also be used as a circuit board for antennas, filters, etc.

[0096] The circuit board can be manufactured by a general method using the above-described laminate.

Example

[0097] Examples are shown below to specifically describe the present invention, but the present invention is not limited to these examples. In the table, “%” and “parts” indicate “mass %” and “parts by mass”, respectively. The various properties shown in the examples were measured by the following methods.

[0098] Film thickness of the film The film thickness of the film was measured using a film thickness meter LZ-373 manufactured by Kett Science Laboratory Co., Ltd.

[0099] Surface roughness of the film The surface roughness Ra of the film was measured using a surface roughness measuring instrument Surtronic DUOII manufactured by Taylor Hobson.

[0100] Adhesion strength between the film and the substrate The adhesion strength between the film and the substrate was measured using an AGS-J autograph (50 N) manufactured by Shimadzu Corporation. As shown in FIG. 1, two cuts were made on the film of the laminate substantially parallel to the long axis direction at 50 mm, and both ends were cut perpendicular to the film in the short axis direction. One end was peeled off by 10 mm and clamped by an upper chuck (omitted in the figure). The substrate was fixed below so that the long side direction was horizontal. When moving the device in the tensile direction, a jig that moves in conjunction with the lateral direction according to the vertical movement distance was used to adjust the angle so that the peeled film was always perpendicular to the substrate in the long side direction. The tensile stress when pulling at 100 mm / min until peeling by 30 mm was measured, and the maximum point stress was taken as the adhesion strength.

[0101] Relative permittivity of the film Using an LCR high tester 3522-50 manufactured by HIOKI, the capacitance was obtained and the relative dielectric constant was calculated from the following formula. C = Ca + Cb (In the formula, C is the capacitance per unit length of the film (pf / m), which is the combination of the capacitance Ca of the flat part and the capacitance Cb of each curved part.) Ca = (ε / ε0) × 2 × (L1 + L2) / T Cb = (ε / ε0) × 2πε0 / Log{(r + T) / r} / r (In the formula, ε0 is the permittivity of vacuum, L1 is the long side of the copper plate, L2 is the short side, and T is the thickness of the film.)

[0102] Comparative Example 1 Electrostatic coating was carried out on a copper plate (thickness 1 mm) using perfluoropolymer powder A (TFE / PPVE copolymer, melting point 301 °C), and this was heated at 350 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0103] Example 1 Electrostatic coating was carried out on a copper plate using PFA primer A (PFA / polyamideimide / polyarylene sulfide = 80 / 10 / 10 (mass%)), and this was heated at 350 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder A, and this was heated at 350 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0104] Example 2 Electrostatic coating was carried out on a copper plate using perfluoropolymer powder A, and this was heated at 350 °C for 30 minutes in a drying furnace under a nitrogen-substituted oxygen-free atmosphere to obtain a film. The properties of this film were evaluated.

[0105] Example 3 Electrostatic coating was carried out on a copper plate using PFA primer A, and this was heated at 350 °C for 30 minutes in a drying furnace under a nitrogen-substituted oxygen-free atmosphere to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder A, and this was heated at 350 °C for 30 minutes in a drying furnace under an oxygen-free atmosphere to obtain a film. The properties of this film were evaluated.

[0106] Comparative Example 2 Electrostatic coating was carried out on a copper plate using perfluoropolymer powder B (TFE / HFP copolymer, melting point 269 °C), and this was heated at 320 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0107] Example 4 Electrostatic coating was carried out on a copper plate using FEP primer B (FEP / polyethersulfone = 80 / 20 (mass%)), and this was heated at 320 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder B, and this was heated at 320 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0108] Example 5 Electrostatic coating was carried out on a copper plate using perfluoropolymer powder B, and this was heated at 290 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0109] Example 6 Electrostatic coating was carried out on a copper plate using perfluoropolymer powder B, and this was heated at 320 °C for 30 minutes in a drying furnace under an oxygen-free atmosphere replaced with nitrogen to obtain a film. The properties of this film were evaluated.

[0110] Example 7 Electrostatic coating was carried out on a copper plate using FEP primer B, and this was heated at 290 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder B, and this was heated at 290 °C for 30 minutes in a drying furnace under an oxygen atmosphere to obtain a film. The properties of this film were evaluated.

[0111] Example 8 Electrostatic coating was carried out on a copper plate using FEP primer B, and this was heated at 320 °C for 30 minutes in a drying oven under an oxygen-free atmosphere replaced with nitrogen to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder B, and this was heated at 320 °C for 30 minutes in a drying oven under an oxygen-free atmosphere to obtain a film. The properties of this film were evaluated.

[0112] Example 9 Electrostatic coating was carried out on a copper plate using perfluoropolymer powder B, and this was heated at 290 °C for 30 minutes in a drying oven under an oxygen-free atmosphere replaced with nitrogen to obtain a film. The properties of this film were evaluated.

[0113] Example 10 Electrostatic coating was carried out on a copper plate using FEP primer B, and this was heated at 290 °C for 30 minutes in a drying oven under an oxygen-free atmosphere replaced with nitrogen to obtain a film. Further, electrostatic coating was carried out using perfluoropolymer powder B, and this was heated at 290 °C for 30 minutes in a drying oven under an oxygen-free atmosphere to obtain a film. The properties of this film were evaluated.

[0114] Comparative Example 3, Examples 11 to 17 Except that perfluoropolymer powder C (TFE / HFP / PPVE copolymer, melting point 257 °C) was used instead of perfluoropolymer powder B, the same operations as in Comparative Example 2 and Examples 4 to 10 were carried out, and the properties of the film were evaluated. These results are shown in Tables 1 and 2.

[0115]

Table 1

[0116]

Table 2

[0117] From the results in Table 1, the laminate of the examples was excellent in the adhesion between the substrate and the film, and had a low surface roughness of the film.

[0118] Example 18 Electrostatic coating was performed on the outer periphery of a rectangular copper wire base material using FEP primer B, and this was heated at 320°C for 30 minutes in a drying furnace under a nitrogen-substituted oxygen-free atmosphere to obtain a film. Further, electrostatic coating was performed using perfluoropolymer powder C, and this was heated at 320°C for 30 minutes in a drying furnace under an oxygen-free atmosphere to obtain a film. The film thickness of the primer layer of this film was 50 μm, and the film thickness of the perfluoropolymer layer was 50 μm. Also, the surface roughness was 0.7 μm, and the relative dielectric constant was 2.3. Furthermore, the adhesion strength with the base material was evaluated by the following procedure. Two pieces were cut approximately parallel to the long axis direction of the rectangular wire base material, and both ends were cut at right angles to the film in the short axis direction, and the ends were peeled off by 10 cm and clamped in the upper chuck of an AGS-J autograph (50 N) (manufactured by Shimadzu Corporation). The conductor was fixed below so that the long side direction was horizontal. When the apparatus was moved in the tensile direction, a jig that moved in conjunction with the movement in the horizontal direction according to the movement distance in the vertical direction was used, and the angle was adjusted so that the peeled film was always perpendicular to the conductor in the long side direction. The tensile stress when pulling at 100 mm / min until peeling by 30 mm was measured, and the adhesion strength corresponding to the maximum point stress was 0.4 (N / mm).

Industrial Applicability

[0119] The laminate of the present disclosure can be suitably used for magnet wires, bus bars, high-frequency substrates, etc., having copper as a base material.

Claims

1. A substrate comprising copper; and a coating containing a perfluoropolymer, A laminate, characterized in that the adhesive strength between the substrate and the coating is 0.2 N / mm or more, and the surface roughness of the coating is less than 15 μm.

2. The perfluoropolymer is The laminate according to claim 1, which is a copolymer containing tetrafluoroethylene (TFE) units and at least one unit selected from the group consisting of perfluoroalkyl vinyl ether (PAVE) units and hexafluoropropylene (HFP) units.

3. 3. The laminate according to claim 1, wherein the perfluoropolymer is a TFE / HFP copolymer.

4. 3. The laminate according to claim 2, wherein the adhesive strength between the substrate and the coating is 0.2 N / mm or more and 1.2 N / mm or less, and the surface roughness of the coating is 0.1 μm or more and less than 1.5 μm.

5. On a substrate containing copper, A primer composition is applied, and then a powder composition containing a perfluoropolymer is applied thereto by electrostatic coating; A method for forming a laminate, comprising heating the perfluoropolymer to a temperature equal to or higher than the melting point thereof to form a film.

6. On a substrate containing copper, A powder composition containing a perfluoropolymer having a melting point of less than 310° C. is applied by electrostatic coating; A method for forming a laminate, comprising heating the perfluoropolymer to a temperature not lower than the melting point of the perfluoropolymer and lower than 320° C. to form a film.

7. On a substrate containing copper, A powder composition containing a perfluoropolymer is applied by electrostatic coating, A method for forming a laminate, comprising heating the perfluoropolymer to a temperature equal to or higher than the melting point of the perfluoropolymer in the absence of oxygen to form a film.

8. A method for forming a laminate, comprising the steps of: combining two or more of the methods for forming a laminate according to claims 5 to 7.

9. 6. The method for forming a laminate according to claim 5, wherein the film is formed by heating to a temperature equal to or higher than the melting point of the perfluoropolymer in an oxygen-free environment.

10. A powder composition containing a perfluoropolymer having a melting point of less than 310° C. is applied by electrostatic coating; 6. The method for forming a laminate according to claim 5, wherein the film is formed by heating the film to a temperature equal to or higher than the melting point of the perfluoropolymer and lower than 320° C. in an oxygen-free environment.

11. 7. The method for forming a laminate according to claim 6, wherein the film is formed by heating in an oxygen-free environment to a temperature equal to or higher than the melting point of the perfluoropolymer and lower than 320°C.

12. The perfluoropolymer is A copolymer containing at least one unit selected from the group consisting of tetrafluoroethylene (TFE) units, perfluoroalkyl vinyl ether (PAVE) units, and hexafluoropropylene (HFP) units; A method for forming a laminate according to any one of claims 5 to 7 and 9 to 11.

13. The primer composition essentially contains a perfluoropolymer, 11. The method for forming a laminate according to claim 5, further comprising at least one resin selected from the group consisting of polyamideimide, polyethersulfone, and polyarylene sulfide.

14. A laminate formed by the method for forming a laminate according to any one of claims 5 to 7 and 9 to 11.

15. The laminate of claim 14, wherein the perfluoropolymer is a TFE / HFP copolymer.

16. An article comprising the laminate according to claim 1 or 2.

17. A magnet wire comprising the laminate according to claim 1 or 2.

18. A busbar comprising the laminate according to claim 1 or 2.

19. A high frequency substrate comprising the laminate according to claim 1 or 2.

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