Laminate and method for forming a 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 insulation, 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 an insulating layer is formed by electrostatically coating a powder coating made of a thermosetting resin such as an epoxy resin on a copper conductor (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 copper-containing substrate 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 copper-containing substrate and a film containing a perfluoropolymer. The laminate is characterized in that the adhesion 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.

[0008] Preferably, the perfluoropolymer is a copolymer comprising tetrafluoroethylene (TFE) units and at least one selected from the group consisting of perfluoroalkyl vinyl ether (PAVE) units and hexafluoropropylene (HFP) units. The perfluoropolymer is preferably a TFE / HFP copolymer. Preferably, the adhesion strength between the substrate 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] This disclosure relates to a copper-containing substrate, A primer composition is applied, and then a powder composition containing a perfluoropolymer is applied by electrostatic coating. This method for forming a laminate is characterized by heating the perfluoropolymer to a temperature above its melting point to form a film. In the above method for forming the laminate, it is preferable to heat the perfluoropolymer to a temperature above its melting point under oxygen-free conditions to form the film. Furthermore, 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. It is preferable to form the film by heating the perfluoropolymer to a temperature above its melting point and below 320°C under oxygen-free conditions.

[0010] This disclosure relates to a copper-containing substrate, A powder composition containing a perfluoropolymer having a melting point of less than 310°C is applied by electrostatic coating. This method for forming a laminate is characterized by heating the perfluoropolymer to a temperature above its melting point and below 320°C to form a film. In the method for forming the laminate described above, it is preferable to form the film by heating the perfluoropolymer to a temperature above its melting point and below 320°C under oxygen-free conditions.

[0011] This disclosure relates to a copper-containing substrate, A powder composition containing a perfluoropolymer is applied by electrostatic coating. This method for forming a laminate is characterized by heating the perfluoropolymer to a temperature above its melting point under oxygen-free conditions to form a film.

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

[0013] In the method for forming the above laminate, the perfluoropolymer is It is preferable that the copolymer comprises 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 described above, the primer composition preferably contains a perfluoropolymer and further includes one or more resins selected from the group consisting of polyamide-imide, polyethersulfone, and polyarylene sulfide.

[0015] This disclosure also refers to a laminate formed by any of the above-described methods for forming a laminate. In a laminate formed by any of the above methods for forming a laminate, it is preferable that the perfluoropolymer is a TFE / HFP copolymer. This disclosure is also an article having the laminate described above. This disclosure also relates to a magnet wire having the laminate described above. This disclosure is also a busbar having the laminate described above. This disclosure also relates to a high-frequency substrate having the laminate described above. [Effects of the Invention]

[0016] The laminate of the present disclosure has excellent adhesion between a base material containing copper and a perfluoropolymer film. Moreover, 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] It is an explanatory diagram showing the state of the film when measuring the adhesion strength between the film and the base material in the examples.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present disclosure will be described in detail. A laminate formed with a perfluoropolymer film having excellent insulation properties on a base material such as copper or a copper alloy is expected to be utilized in 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 problems such as peeling and cracking of the film and non-uniform film thickness occur when bending 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] This disclosure provides a laminate with excellent adhesion by forming a laminate having a perfluoropolymer film on a copper-containing substrate by at least one of the following methods (1) to (3). Furthermore, the laminate of this disclosure also has excellent surface smoothness. (1) A primer composition is applied to a copper-containing substrate, then a powder composition containing a perfluoropolymer is applied by electrostatic coating, and the mixture is heated to a temperature above 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 to a copper substrate by electrostatic coating, and the surface is heated to a temperature above the melting point of the perfluoropolymer and below 320°C to form a film. (3) A powder composition containing a perfluoropolymer is applied to a copper substrate by electrostatic coating, and the mixture is heated to a temperature above the melting point of the perfluoropolymer under oxygen-free conditions to form a film.

[0022] By forming the laminate as described above, a laminate can be obtained in which the adhesion strength between the copper-containing substrate and the coating is 0.2 N / mm or higher, and the surface roughness of the coating is less than 15 μm. Such laminates exhibit particularly excellent performance when applied to magnet wires, busbars, high-frequency substrates, etc., that use copper-containing conductors as a base material.

[0023] (Laminated structure) The laminate of this disclosure comprises a copper-containing substrate and a perfluoropolymer-containing film, wherein the adhesion strength between the substrate and the film is 0.2 N / mm or greater, and the surface roughness of the film is less than 15 μm.

[0024] In the laminate of this disclosure, the adhesion strength between the substrate and the coating is 0.2 N / mm or higher. Because the adhesion strength is 0.2 N / mm or higher, when the laminate is bent, peeling or cracking of the coating does not occur, and problems such as uneven film thickness do not occur. The adhesion strength between the substrate and the coating is preferably 0.3 N / mm or higher, and more preferably 0.4 N / mm or higher. There is no particular upper limit to the adhesion strength, but 1.2 N / mm or lower is sufficient, and even 1.0 N / mm or lower will sufficiently achieve the effects required in this disclosure. In this specification, the adhesion strength is the value obtained by the method for measuring adhesion strength in the following examples.

[0025] Furthermore, the above-mentioned adhesion strength refers to the adhesion strength between the substrate and the primer film when a primer film is applied to the substrate surface in advance, as in the laminate formation method described in (1) above, and then a film made of a powder composition containing a perfluoropolymer is applied.

[0026] The surface roughness of the coating is preferably less than 1.5 μm. A surface roughness of less than 1.5 μm is advantageous because it allows for good electrical properties. The surface roughness of the film is preferably 1.0 μm or less, and more preferably 0.7 μm or less. The lower limit of the surface roughness is not particularly limited, but it is preferably 0.01 μm or more, and more preferably 0.1 μm or more. In this specification, surface roughness is the value obtained by the surface roughness measurement method in the following examples. To achieve a surface roughness of less than 1.5 μm of the coating, for example, heating at a temperature 20°C or more above the melting point of the perfluoropolymer for 20 minutes or more can be used.

[0027] (base material) The substrate used in the laminate of this disclosure contains copper, and includes elemental copper and copper alloys. For example, examples of elemental copper include tough pitch copper and oxygen-free copper. Other examples include composite copper composed of trace components such as aluminum, nickel, and silver, and copper-aluminum clad materials. Preferably, the substrate used in the laminate of this disclosure is elemental copper.

[0028] The above-mentioned substrate may be subjected to surface treatments such as cleaning and sandblasting as necessary. Surface treatment of the substrate to create a rough surface increases the anchoring effect with the powder composition used during film formation, thereby improving adhesion to the film.

[0029] (Perfluoropolymer) The perfluoropolymer included in the coating of the laminate of this disclosure is not particularly limited, and any known perfluoropolymer can be used. Examples of such perfluoropolymers include those obtained by polymerization using one or more perfluoro monomers such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE) as monomer components.

[0030] The PAVE mentioned above is not particularly limited and includes one or more perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), and perfluoropropyl vinyl ether (PPVE), with perfluoropropyl vinyl ether (PPVE) being particularly preferred.

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

[0032] Specifically, TFE / PAVE copolymer (PFA), TFE / HFP copolymer (FEP), TFE / PAVE / HFP copolymer, etc. are preferred. In particular, TFE / HFP copolymers and TFE / PAVE / HFP copolymers are preferred because they can be formed 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 heat of fusion curve when the temperature is increased 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. Within the above melt flow rate range, interlayer adhesion is good. Furthermore, the flow during coating is good, resulting in high surface smoothness. Additionally, prolonged heating is not required to achieve the desired film smoothness, and degradation of the perfluoropolymer is not a problem. A more preferable lower limit is 5g / 10 mins, and a more preferable upper limit is 30g / 10 mins.

[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-mentioned perfluoropolymer can be made to have an MFR within the above-mentioned range by adjusting the molecular weight, etc.

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

[0037] The above-mentioned film may contain, in addition to the perfluoropolymer, a heat stabilizer, a coloring pigment additive, and the like, as described later. In the above-mentioned coating, it is preferable that the perfluoropolymer is contained in an amount of 70 to 100% by mass. A perfluoropolymer content within this range is advantageous in that it can exhibit good electrical properties. 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 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 become difficult to miniaturize equipment such as motors. Conversely, if the film thickness is too thin, sufficient insulation may not be achieved.

[0039] Furthermore, the dielectric constant of the above-mentioned film is preferably 2.1 to 2.8, and more preferably 2.6 μm or less. Having a dielectric constant within this range is advantageous because it allows for good insulating properties. In this specification, the relative permittivity is the value obtained by the method for measuring the relative permittivity in the following examples.

[0040] (Method for forming a laminate) The formation of the laminate according to this disclosure is preferably carried out by using the above-mentioned perfluoropolymer-containing powder composition, applying it to a substrate by electrostatic coating, and then heating to form a film.

[0041] (Powder composition) In this disclosure, the powder composition used for film formation includes the perfluoropolymer powder described above.

[0042] The above powder composition preferably has an average particle size of 1 to 100 μm. If the particle size is less than 1 μm, electrostatic repulsion is likely to occur when applied, making it difficult to form a film. If the particle size 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 made to fall within the above range by adjusting the grinding and classification conditions in the powder composition manufacturing method described later. In this specification, the average particle diameter is a value measured by laser diffraction. Specifically, it is the volume-based median diameter measured by Microtrac MT-3300II.

[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, it tends to cause foaming during painting or lead to an increase in the number of coats, making electrostatic painting difficult. If it exceeds 1.1 g / ml, it tends to become difficult to industrially manufacture such a powder composition. The lower limit of the preferred apparent density is 0.7 g / ml, and the upper limit is 1.0 g / ml. In this specification, the 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. If the powder composition contains the above heat stabilizer, it is possible to prevent discoloration and foaming of the coating film that may occur when the perfluoropolymer becomes unstable when heated to a temperature near or above its melting point. The heat stabilizer is preferably at least one selected from the group consisting of amine-based antioxidants, organic sulfur-containing compounds, and metal powders, in order to prevent oxidation of the perfluoropolymer.

[0046] Examples of the above-mentioned amine-based antioxidants include aromatic amines having aromatic hydrocarbon groups such as phenyl groups and naphthyl groups in their molecules. Examples include 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, phenylcyclohexy-p-phenylenediamine, and styrene-diphenylamine.

[0047] Examples of the above organic sulfur-containing compounds include mercaptobenzoimidazole compounds such as 2-mercaptobenzoimidazole and 2-mercaptomethylbenzimidazole; 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, 2-(4'-morpholinodithio)benzothiazole, N-cyclohexyl-2-benzothiazolyl sulfenamide, N-oxydiethylene-2-benzothiazolyl sulfenamide, and N-tert-butyl-2-benzo Examples include mercaptobenzothiazole compounds such as thiazolyl sulfenamide; mercaptoimidazoline compounds such as 2-mercaptoimidazoline; and dithiocarbamic acids such as pentamethylenedithiocarbamic acid, pipecholyldithiocarbamic acid, dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dibutyldithiocarbamic acid, and N-ethyl-N-phenyldithiocarbamic acid. These may also be metal salts such as Zn, Sn, Cd, Cu, and Fe; or organic salts such as piperidine salts and pipecholyl salts.

[0048] Examples of the above-mentioned organic sulfur-containing compounds include thiram compounds, such as thiram monosulfides like tetramethylthiram monosulfide; thiram disulfides like tetramethylthiram disulfide, tetraethylthiram disulfide, and tetrabutylthiram disulfide; and other thiram compounds such as dipentamethylenethiram tetrasulfide. The above-mentioned organic sulfur-containing compound may also be, for example, thiourea derivatives such as N,N'-diethylthiourea, dibutylthiourea, and dilaurylthiourea.

[0049] Examples of the above-mentioned metal powders include one or more of the following: 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 amine-based antioxidant rather than using it alone.

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

[0051] The above-mentioned heat stabilizers can be manufactured by conventionally known methods, but commercially available products can usually be used.

[0052] The amount of the heat stabilizer is preferably 0.001 to 5 parts by mass per 100 parts by mass of the perfluoropolymer. If it is less than 0.001 parts by mass, the heat stability of the perfluoropolymer may deteriorate, and if it exceeds 5 parts by mass, discoloration of the resulting film and foaming due to decomposition of the heat stabilizer may occur, which is undesirable. More preferably, it is 0.003 to 2 parts by mass.

[0053] The above powder composition may contain a coloring pigment. Examples of coloring pigments include titanium dioxide, cobalt oxide, carbon, chromium oxide, iron oxide, and mica. The above-mentioned coloring pigment is preferably in an amount of 0.001 to 5 parts by mass per 100 parts by mass of the above-mentioned TFE-based copolymer. If it is less than 0.001 parts 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 contain additives, etc., as needed, in combination with the above perfluoropolymer and the stabilizer and / or coloring pigment, which may be used as desired. The above additives, etc. are not particularly limited and include, for example, those commonly used in powder compositions. Examples of the above-mentioned additives include, for example, rust-preventive pigments, calcined pigments and other pigments for rust prevention; coating reinforcing materials such as carbon fibers, glass fibers, glass flakes, and mica for preventing shrinkage of the coating film; and conductive materials such as conductive carbon for imparting conductivity. Leveling agents and antistatic agents may also be used.

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

[0056] The average particle size of the heat stabilizer, coloring pigment, and additives is preferably 0.1 to 70 μm, and more preferably 0.1 to 50 μm. When these particle sizes are within this range, they can be uniformly dispersed in the composition and stably coated. These average particle sizes are measured by laser diffraction. Specifically, they are volume-based median diameters measured using the Microtrac MT-3300II.

[0057] The powder composition used in this disclosure can be produced by mixing the above-mentioned components. By using various grinding machines such as jet mills, hammer mills, and pin mills, and combining them as needed, appropriate crushing can be achieved by adjusting the grinding conditions, grinding time, and the blending ratio of resin components used in combination.

[0058] The method for forming a laminate according to this disclosure is particularly preferable in which a laminate comprising a copper substrate and a perfluoropolymer film is formed by at least one of the following methods (1) to (3). By forming the laminate in this manner, adhesion and surface smoothness can be improved. (1) A primer composition is applied to a copper-containing substrate, and then the powder composition is applied by electrostatic coating and heated to a temperature above the melting point of the perfluoropolymer to form a film. (2) The powder composition containing a perfluoropolymer having a melting point of less than 310°C is applied to a copper substrate by electrostatic coating, and the surface is heated to a temperature above the melting point of the perfluoropolymer and below 320°C to form a film. (3) The powder composition is applied to a copper-containing substrate by electrostatic coating, and a film is formed by heating to a temperature above the melting point of the perfluoropolymer under oxygen-free conditions.

[0059] The method described in (1) above involves forming a primer film on the substrate beforehand. When forming a perfluoropolymer film on a copper-containing substrate, applying a primer layer beforehand is preferable because it can further improve the adhesion between the perfluoropolymer layer and the substrate.

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

[0061] The primer composition preferably further uses one or more heat-resistant resins selected from the group consisting of polyamide-imide (PAI), polyethersulfone (PES), and polyarylene sulfide (PAS).

[0062] (Polyamide-imide) PAI is a resin composed of a polymer having amide and imide bonds in its molecular structure. The above PAI is not particularly limited, and examples include resins composed of high molecular weight polymers obtained by reactions such as the reaction of an aromatic diamine having an amide bond in the molecule with an aromatic tetravalent carboxylic acid such as pyromellitic acid; the reaction of an aromatic trivalent carboxylic acid such as trimellitic anhydride with a diamine such as 4,4-diaminophenyl ether or a diisocyanate such as diphenylmethane diisocyanate; and the reaction of a dibasic acid having an aromatic imide ring in the molecule with a diamine. As the above PAI, a polymer having an aromatic ring in the main chain is preferred in terms of excellent heat resistance.

[0063] PAI preferably has a glass transition temperature of 200°C or higher, more preferably 250°C or higher. A glass transition temperature within this range can improve the heat resistance of the primer composition. Furthermore, 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 using a differential scanning calorimetry (DSC) device.

[0064] PAI preferably has a melting point of 250°C or higher, more preferably 260°C or higher. Having a melting point within this range improves the heat resistance of the resin composition. Furthermore, the melting point of PAI is preferably 320°C or lower, and more preferably 300°C or lower. The above melting point is measured using a differential scanning calorimetry (DSC) device.

[0065] (Polyethersulfone) The above-mentioned PES exhibits excellent adhesion to the object to be coated, possesses sufficient heat resistance even at the firing temperature during the formation of the coating film, and the resulting coating film has excellent corrosion resistance and water vapor resistance.

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

[0067] [ka] This resin is made of a polymer having repeating units represented by .

[0068] PES is not particularly limited, and examples include resins made from polymers obtained by polycondensation of dichlorodiphenylsulfone and bisphenol.

[0069] The PES preferably has a glass transition temperature of 200°C or higher. More preferably, it is 205°C or higher, and even more preferably, 210°C or higher. A glass transition temperature within this range can improve the heat resistance of the primer composition. Furthermore, the glass transition temperature of the 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) device.

[0070] (Polyarylene sulfide) For example, the following general formula can be used for PAS: -(Ar-S)- Examples include resins having repeating units represented by the formula (wherein Ar represents an arylene group and S represents sulfur), and the content of the repeating units in the resin is preferably 70 mol% or more. Examples of arylene groups 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, etc. Although PAS can be broadly classified into resins having crosslinked or branched structures (crosslinked type) and resins substantially without crosslinked or branched structures (linear type), in this disclosure, either the crosslinked type or the linear type can be used without any problems. For example, polyphenylene sulfide is a preferred example of PAS.

[0071] The glass transition temperature of the PAS is preferably 70°C or higher. More preferably, it is 80°C or higher, and even more preferably, 85°C or higher. A glass transition temperature within the above range can improve the heat resistance of the resin composition. Furthermore, the glass transition temperature of the 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) device.

[0072] PAS preferably has a melting point of 180°C or higher, more preferably 190°C or higher. Having a melting point within this range improves the heat resistance of the resin composition. Furthermore, the melting point of PAS is preferably 380°C or lower, and more preferably 350°C or lower. The melting point is measured using a differential scanning calorimetry (DSC) device.

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

[0074] The above resin may also preferably consist of 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 PAI is included in addition to PAS or PES as the above resin, a coating film with excellent secondary adhesion (adhesion to the substrate after repeated heating and cooling of the coating film) can be obtained. The above resin is more preferably PAS and PAI, that is, a mixture of PAS and PAI. PAS, PES, and PAI may each consist of one or more types.

[0075] When the above resin is PAS or PES and PAI, it is preferable that the amount of PAS or PES is 20 to 80% by mass of the total amount of 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 above-mentioned fluororesin to the above-mentioned heat-resistant resin is within the above range, the adhesive strength between the perfluoropolymer layer and the primer layer, and the adhesive strength between the primer layer and the substrate can be increased.

[0077] The above primer composition may optionally contain other additives. The above-mentioned primer composition is preferably a powder composition, and it is preferable to form the primer layer by applying it by electrostatic coating and heating, similar to the film formation of perfluoropolymers. In forming the primer layer, it is also preferable to use the methods described in (2) and / or (3) above.

[0078] The thickness of the primer film is preferably 10 to 100 μm, more preferably 20 to 80 μm. A primer film thickness within this range is advantageous because it allows for good adhesion between the perfluoropolymer layer and the substrate.

[0079] The above-mentioned powder composition can be applied to the primer film by electrostatic coating and then heated and baked to form a film. The electrostatic coating described above is not particularly limited and can be carried out using conventional methods.

[0080] The heating temperature is preferably above the melting point of the perfluoropolymer. Specifically, it is preferably above the melting point + 20°C. 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 coating. The heating time is preferably 5 minutes or more, and 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 coating.

[0081] As described above, method (2) involves applying the powder composition containing a perfluoropolymer having a melting point of less than 310°C onto a substrate by electrostatic coating, and then heating it to a temperature above the melting point of the perfluoropolymer and below 320°C to form a film.

[0082] When forming a coating on the surface of a copper-containing substrate using a powder composition containing a perfluoropolymer, heating the powder composition at temperatures above 320°C can accelerate copper oxidation, potentially impairing the adhesion between the copper substrate and the perfluoropolymer coating. Therefore, in method (2), heating at a temperature of less than 320°C suppresses the oxidation of copper and improves the adhesion between the copper substrate and the perfluoropolymer film. The heating temperature is preferably less than 300°C.

[0083] In the method described in (3) above, the powder composition is applied by electrostatic coating and heated to a temperature above the melting point of the perfluoropolymer under oxygen-free conditions. By performing heating under oxygen-free conditions, oxidation of the substrate can be suppressed, preventing the formation of a fragile oxide layer, resulting in good adhesion to the substrate.

[0084] Heating can be performed in an oxygen-free environment using an inert gas containing no more than 1% by mass of oxygen. Examples of inert gases include nitrogen gas.

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

[0086] Of the methods (1) to (3) described above, it is particularly preferable to use methods (1), (2), and (3) in combination. It is also preferable to use methods (1) and (3), or methods (2) and (3) in combination. By using these two methods in combination, the formation of oxide films can be suppressed, and by applying the primer composition, good adhesion to the copper substrate can be achieved.

[0087] By forming the laminate as described above, a laminate with excellent adhesion and surface smoothness can be obtained. This disclosure also relates to a method for forming a laminate, characterized by coating a copper-containing substrate with a primer composition, then applying the powder composition by electrostatic coating, and heating to a temperature above the melting point of the perfluoropolymer to form a film.

[0088] Furthermore, this disclosure also relates to a method for forming a laminate, characterized by applying the powder composition containing a perfluoropolymer having a melting point of less than 310°C to a copper substrate by electrostatic coating, and then heating it to a temperature above the melting point of the perfluoropolymer and below 320°C to form a film.

[0089] Furthermore, this disclosure also relates to a method for forming a laminate characterized by applying the powder composition to a copper-containing substrate by electrostatic coating and then heating it to a temperature above the melting point of the perfluoropolymer under oxygen-free conditions to form a film.

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

[0091] This disclosure is also an article having the above-mentioned laminate. Specifically, the laminate of this disclosure is suitably used in articles such as magnet wires, busbars, and high-frequency substrates. These conductors are typically copper or copper alloys, and the laminates of this disclosure are preferably used.

[0092] This disclosure is also a magnet wire having the laminate of this disclosure. Magnet wire is used in coils for motors and transformers, among other applications. Examples of motors in which magnet wire is used include electric vehicle motors, air conditioner and refrigerator compressor motors, and sealed motors.

[0093] This disclosure is also a busbar having the laminate of this disclosure. Busbars are used in electric vehicles and as wiring components for transmitting electric current within power conversion devices such as inverters and converters. Furthermore, busbars are used in distribution boards (cubicles), control panels, batteries, etc., and are designed to conduct large amounts of current. Busbars have low electrical resistance, which allows them to efficiently supply large amounts of current to various parts. Furthermore, because wiring is completed simply by securing the busbars with screws, it's possible to distribute high-capacity power to the entire panel, even in large distribution and control panels, relatively easily. Taking advantage of these characteristics, busbars are widely used as an alternative to cables and wires. For example, in battery modules with multiple batteries, the terminals of one battery are electrically connected to the terminals of another battery via a busbar.

[0094] The laminate of this disclosure is suitably used as a circuit board. A circuit board is a plate-shaped component used to electrically connect electronic components such as semiconductors and capacitor chips, while simultaneously arranging and fixing them within a limited space. The configuration of the circuit board formed from the laminate of this disclosure is not particularly limited. The circuit board may be a rigid board, a flexible board, or a rigid-flexible board. The circuit board may be a single-sided board, a single-sided board, a double-sided board, or a multilayer board (such as a pull-up board). It can be suitably used for flexible substrates and rigid substrates. In particular, it can be suitably used as a substrate for high-frequency applications of 10 GHz or higher. This disclosure is also a high-frequency substrate having the laminate of this disclosure.

[0095] In this disclosure, a high-frequency circuit includes not only circuits that simply transmit high-frequency signals, but also circuits that have transmission lines for transmitting signals other than high-frequency signals, such as transmission lines that convert high-frequency signals into low-frequency signals and output the generated low-frequency signals to the outside, and transmission lines that supply power for driving high-frequency compatible components, all located on the same plane. The high-frequency substrate of this disclosure can be suitably used in mobile communication terminals such as mobile phones, smartphones, and tablet devices, communication equipment 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, and other applications.

[0096] Circuit boards can be manufactured using the laminates described above by general methods. [Examples]

[0097] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the table, "%" and "parts" refer to "mass%" and "parts by mass," respectively. The properties shown in the examples were measured by the following method.

[0098] Film thickness The film thickness was measured using a Kett Scientific Instruments LZ-373 film thickness gauge.

[0099] Surface roughness of the coating The surface roughness Ra of the coating was measured using a Taylor Hobson Sartronic DUOII surface roughness analyzer.

[0100] Adhesion strength between the coating and the substrate The adhesion strength between the coating and the substrate was measured using a Shimadzu AGS-J Autograph (50N). As shown in Figure 1, two approximately parallel cuts of 50 mm in the long axis direction were made on the coating of the laminate, and both ends of these cuts were made perpendicular to the coating in the short axis direction. One end was peeled off by 10 mm and clamped in the upper chuck (not shown in the figure). The substrate was fixed to the bottom so that its long side was horizontal. When the device was moved in the tensile direction, a jig that moved laterally in conjunction with the vertical movement distance was used to adjust the angle so that the peeled film was always perpendicular to the substrate in the long plane direction. The tensile stress was measured when the material was pulled at 100 mm / min until 30 mm of peeling was achieved, and the maximum point stress was defined as the adhesion strength.

[0101] Relative permittivity of the coating Using a HIOKI LCR high-tester 3522-50, capacitance was obtained and the relative permittivity was calculated using the following formula. C = Ca + Cb (In the formula, C is the capacitance per unit length of the film (pf / m), which is the sum of the capacitance Ca of the flat section and the capacitance Cb of each curved section.) 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 coating.)

[0102] Comparative Example 1 A copper plate (1 mm thick) was electrostatically coated with perfluoropolymer powder A (TFE / PPVE copolymer, melting point 301°C), and the resulting film was heated in a drying oven under an oxygen atmosphere at 350°C for 30 minutes. The properties of this film were then evaluated.

[0103] Example 1 A copper plate was electrostatically coated using PFA primer A (PFA / polyamide-imide / polyarylene sulfide = 80 / 10 / 10 (mass%)), and the resulting film was obtained by heating it in a drying oven under an oxygen atmosphere at 350°C for 30 minutes. Furthermore, electrostatic coating was performed using perfluoropolymer powder A, and the resulting film was obtained by heating it in a drying oven under an oxygen atmosphere at 350°C for 30 minutes. The properties of these films were evaluated.

[0104] Example 2 A copper plate was electrostatically coated with perfluoropolymer powder A, and the resulting film was heated at 350°C for 30 minutes in a drying oven under a nitrogen-purged, oxygen-free atmosphere to obtain a coating. The properties of this coating were then evaluated.

[0105] Example 3 A copper plate was electrostatically coated using PFA primer A, and then heated in a drying oven under a nitrogen-purged, oxygen-free atmosphere at 350°C for 30 minutes to obtain a film. Furthermore, a film was obtained by electrostatically coating using perfluoropolymer powder A, and then heated in a drying oven under an oxygen-free atmosphere at 350°C for 30 minutes. The properties of these films were evaluated.

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

[0107] Example 4 A copper plate was electrostatically coated using FEP primer B (FEP / polyethersulfone = 80 / 20 (mass%)), and the resulting film was obtained by heating it in a drying oven under an oxygen atmosphere at 320°C for 30 minutes. Furthermore, electrostatic coating was performed using perfluoropolymer powder B, and the resulting film was obtained by heating it in a drying oven under an oxygen atmosphere at 320°C for 30 minutes. The properties of these films were evaluated.

[0108] Example 5 A copper plate was electrostatically coated with perfluoropolymer powder B, and the resulting film was heated in a drying oven under an oxygen atmosphere at 290°C for 30 minutes. The properties of this film were then evaluated.

[0109] Example 6 A copper plate was electrostatically coated with perfluoropolymer powder B, and the resulting film was heated at 320°C for 30 minutes in a drying oven under a nitrogen-purged, oxygen-free atmosphere to obtain a coating. The properties of this coating were then evaluated.

[0110] Example 7 A copper plate was electrostatically coated using FEP primer B, and then heated in a drying oven under an oxygen atmosphere at 290°C for 30 minutes to obtain a film. Furthermore, electrostatic coating was performed using perfluoropolymer powder B, and this was also heated in a drying oven under an oxygen atmosphere at 290°C for 30 minutes to obtain a film. The properties of these films were evaluated.

[0111] Example 8 A copper plate was electrostatically coated using FEP primer B, and then heated in a drying oven under a nitrogen-purged, oxygen-free atmosphere at 320°C for 30 minutes to obtain a film. Furthermore, electrostatic coating was performed using perfluoropolymer powder B, and this was also heated in a drying oven under an oxygen-free atmosphere at 320°C for 30 minutes to obtain a film. The properties of these films were evaluated.

[0112] Example 9 A copper plate was electrostatically coated with perfluoropolymer powder B, and the resulting film was heated at 290°C for 30 minutes in a drying oven under a nitrogen-purged, oxygen-free atmosphere to obtain a coating. The properties of this coating were then evaluated.

[0113] Example 10 A copper plate was electrostatically coated using FEP primer B, and then heated in a drying oven under a nitrogen-purged, oxygen-free atmosphere at 290°C for 30 minutes to obtain a film. Furthermore, electrostatic coating was performed using perfluoropolymer powder B, and this was also heated in a drying oven under an oxygen-free atmosphere at 290°C for 30 minutes to obtain a film. The properties of these films were evaluated.

[0114] Comparative Example 3, Examples 11-17 Except for using perfluoropolymer powder C (TFE / HFP / PPVE copolymer, melting point 257°C) instead of perfluoropolymer powder B, the same procedure as in Comparative Example 2 and Examples 4-10 was performed, and the properties of the coating were evaluated. These results are shown in Tables 1 and 2.

[0115] [Table 1]

[0116] [Table 2]

[0117] The results in Table 1 show that the laminates in the examples exhibited excellent adhesion between the substrate and the coating, and had low surface roughness of the coating.

[0118] Example 18 A copper flat wire substrate was electrostatically coated with FEP primer B, and then heated in a drying oven under a nitrogen-purged, oxygen-free atmosphere at 320°C for 30 minutes to obtain a coating. Furthermore, electrostatic coating was performed using perfluoropolymer powder C, and then heated in a drying oven under an oxygen-free atmosphere at 320°C for 30 minutes to obtain a coating. The primer layer of this film had a thickness of 50 μm, and the perfluoropolymer layer also had a thickness of 50 μm. The surface roughness was 0.7 μm, and the dielectric constant was 2.3. Furthermore, the adhesion strength to the substrate was evaluated using the following procedure. Two flat rectangular wires were placed approximately parallel to each other, 50 mm in the longitudinal direction, and the coating at both ends was cut perpendicular to the short axis direction. 10 cm of the coating was then peeled off and the wires were clamped in the upper chuck of an AGS-J Autograph (50N) (manufactured by Shimadzu Corporation). The conductors were fixed to the bottom so that their longitudinal direction was horizontal. When the device was moved in the tensile direction, a jig that moved in conjunction with the longitudinal movement distance was used to adjust the angle so that the peeled coating was always perpendicular to the conductor in the longitudinal direction. The tensile stress was measured when the wire was pulled at 100 mm / min until 30 mm was peeled off, and the adhesion strength corresponding to the maximum point stress was 0.4 (N / mm). [Industrial applicability]

[0119] The laminate of this disclosure can be suitably used in magnet wires, busbars, high-frequency substrates, etc., using copper as the base material.

Claims

1. A laminate having a film containing a perfluoropolymer directly on a copper-containing substrate, wherein the perfluoropolymer is at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer. A laminate characterized in that the adhesion 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. On a substrate containing copper, A laminate having a film containing a perfluoropolymer via a primer film, The primer film comprises at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer, The perfluoropolymer is at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer. A laminate characterized in that the adhesion strength between the substrate and the primer film is 0.2 N / mm or more, and the surface roughness of the film is less than 15 μm.

3. The laminate according to claim 1 or 2, wherein the perfluoropolymer is a TFE / HFP copolymer.

4. The laminate according to claim 1 or 2, wherein the adhesion strength between the substrate 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.

5. On a copper-containing substrate, A primer composition is applied to form a primer film, and then a powder composition containing a perfluoropolymer is applied onto the primer film by electrostatic coating. A method for forming a laminate, characterized by heating the perfluoropolymer to a temperature above its melting point and below 320°C to form a film, The primer composition comprises at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer, A method for forming a laminate, wherein the perfluoropolymer is at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer.

6. Directly onto a copper-containing substrate, A powder composition containing a perfluoropolymer having a melting point of 270°C or lower is applied by electrostatic coating. A method for forming a laminate, characterized by heating the perfluoropolymer to a temperature above its melting point and below 300°C to form a film, A method for forming a laminate, wherein the perfluoropolymer is at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer.

7. Directly onto a copper-containing substrate, A powder composition containing a perfluoropolymer is applied by electrostatic coating. A method for forming a laminate, characterized by heating the perfluoropolymer to a temperature above its melting point and below 320°C under oxygen-free conditions to form a film, A method for forming a laminate, wherein the perfluoropolymer is at least one selected from the group consisting of tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer and tetrafluoroethylene (TFE) / perfluoroalkyl vinyl ether (PAVE) / hexafluoropropylene (HFP) copolymer.

8. A powder composition containing a perfluoropolymer having a melting point of 270°C or lower is applied by electrostatic coating. The method for forming a laminate according to claim 5, characterized in that the film is formed by heating the perfluoropolymer to a temperature above its melting point and below 300°C.

9. The method for forming a laminate according to claim 5, characterized in that the film is formed by heating the perfluoropolymer to a temperature above its melting point and below 320°C under oxygen-free conditions.

10. A powder composition containing a perfluoropolymer having a melting point of 270°C or lower is applied by electrostatic coating. The method for forming a laminate according to claim 5, characterized in that the film is formed by heating the perfluoropolymer to a temperature above its melting point and below 300°C under oxygen-free conditions.

11. The method for forming a laminate according to claim 6, characterized in that the film is formed by heating the perfluoropolymer to a temperature above its melting point and below 300°C under oxygen-free conditions.

12. The method for forming a laminate according to any one of claims 5, 9, or 10, characterized in that the primer composition further comprises one or more resins selected from the group consisting of polyamide-imide, polyethersulfone, and polyarylene sulfide.

13. An article having the laminate according to claim 1 or 2.

14. A magnet wire having the laminate according to claim 1 or 2.

15. A bus bar having the laminate according to claim 1 or 2.

16. A high-frequency substrate having the laminate according to claim 1 or 2.

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