JP2009061446A - Method of treating long object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of heat-treating a long object such as a textile, a film, a sheet, a metal foil, and a metal foil laminate capable of efficiently converting a metal foil laminate prepared by directly applying a polyimide resin solution in particular onto a metal foil and subsequently subjecting it to a preliminary drying treatment, into a metal foil laminate free of curling and excellent in such a characteristic as dimensional precision, moisture absorption characteristics, adhesion strength, and the reliability thereof (consistent adhesion strength subsequent to the heat treatment, for example) at a high yield. <P>SOLUTION: The method of heat-treating a metal foil laminate prepared by continuously applying a polyimide resin solution onto a metal foil and subjecting the resulting metal foil laminate to a preliminary drying treatment is characterized in that the metal foil laminate is continuously conveyed by a specific conveying method and heat-treated under a specific condition in a furnace equipped with a far-infrared heater. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for treating a long object, and more specifically, drying a long object after impregnating or coating a long object such as a film, a textile fabric, a sheet, and a metal foil with water or an organic solvent solution, and The present invention relates to a method for efficiently performing a heat treatment with a high yield and a method for treating a long object having excellent performance such as dimensional stability and moisture absorption characteristics.

  Conventionally, drying and heat treatment after impregnating or coating long materials such as textile fabrics, films, sheets and metal foils with water or organic solvent solutions are usually performed continuously at a constant rate in a heating zone of a certain length. It is done by passing. However, in this method, when the boiling point of the solvent is high, curling (warping) is likely to occur during drying or heat treatment, and when the coating thickness is thick, it is difficult to dry efficiently with good yield. Met. In particular, when heat treating a metal foil laminate obtained by applying a polyimide resin solution and / or its precursor to metal foil and initially drying it as a long object, the curl is large and it is difficult to manufacture with high productivity. In addition, efficient drying was difficult. In addition, the curl is large, and the properties of the product itself such as appearance and dimensional stability are also unfavorable. Simply drying it will result in properties such as moisture absorption properties, adhesive strength, and reliability (such as adhesive strength after heat treatment). There was a disadvantage of being inferior.

  In order to solve these problems, as disclosed in the following documents, various methods such as heat treatment by wrapping around a cylindrical drum have been studied so far. It is not a highly productive system, and the characteristics of the product itself such as appearance, dimensional stability, and adhesive strength are not always sufficient.

JP-A-57-50670 JP-A-60-15728 JP 55-75289 A JP-A 61-307789 JP-A-5-50547

  From the background art as described above, the object of the present invention is to provide a fiber woven fabric, film, sheet, metal foil, in particular, a metal foil laminate in which a polyimide resin solution or / and its precursor is directly applied to metal foil and initially dried. By heat-treating, a metal foil laminate having no curling and excellent dimensional accuracy is intended to be efficiently dried and manufactured with a high yield. Furthermore, it is intended to improve characteristics such as moisture absorption characteristics, adhesive strength, and reliability (such as adhesive strength after heat treatment).

As a result of diligent research to achieve the above object, the present inventors have conducted a heat treatment on a metal laminate obtained by continuously applying a polyimide resin solution and / or its precursor to a metal foil and initial drying. It has been found that this can be achieved in a far-infrared heating type heating furnace, preferably further continuously conveyed by a specific conveying method and heat-treated, and the present invention has been achieved.
That is, the present invention has the following configuration.
(1) In the continuous processing method of a long thing including the process of carrying and heat-treating a long thing continuously, this heat processing is a far-infrared heating system, The long thing processing method characterized by the above-mentioned.
(2) The long object processing method according to (1), wherein the transport is a staggered transport system.
(3) The long material treatment according to (1) or (2), wherein the long material is a metal foil laminate in which a polyimide resin solution and / or a precursor thereof is applied to metal foil and initially dried. Method.
(4) A long object obtained from the long object processing method according to any one of (1) to (3).

  As described above, the long object of the present invention is manufactured by continuous conveyance by a far-infrared heating method, preferably by employing a specific conveyance method. For this reason, a product excellent in dimensional stability, adhesive strength, reliability of adhesive strength, and moisture absorption characteristics without curling can be manufactured with good yield, and is industrially useful.

  As long objects applied to the present invention, for example, films and sheets made of various polymers, foils made of various metals, thin plates that can be processed in a roll shape, and the like, It can be applied to heat treatment such as drying, aging and curing. A particularly preferable application example is a case where a metal foil laminate obtained by applying a polyimide resin solution and / or a precursor thereof to a metal foil and initially drying it is heat-treated and dried.

  As the metal foil used for producing the metal foil laminate, copper foil, aluminum foil, steel foil, nickel foil, and the like can be used. A metal foil treated with the above metal can also be used. The thickness of the metal foil is not particularly limited, but for example, a metal foil of 1 to 50 μm, preferably 3 to 35 μm, more preferably 3 to 18 μm can be suitably used. When the thickness of the metal foil is less than 1 μm, the yield at the time of conveyance is lowered, and when it is greater than 50 μm, the winding as a long object is unsatisfactory and the winding property is inferior, and the yield is lowered. As the polyimide-based resin to be used, any resin may be basically used as long as it has a thermal expansion coefficient equivalent to that of the metal foil and is excellent in heat resistance, but preferably aromatic polyimide or aromatic resin. Polyamideimide. The thickness of the resin is not particularly limited, but is, for example, 1 to 200 μm, preferably 5 to 75 μm, and more preferably 8 to 35 μm. When the thickness of the resin is 200 μm or more, like a copper foil, it is unwound as a long object, is inferior in winding property, and the yield decreases. If it is less than 1 μm, there is no problem in production, but it is practically difficult to use as a metal foil laminate, for example, a printed wiring board. The width is not limited, and a commercially available copper foil can be used as it is, for example, having a width of 250 mm to 1080 mm.

  An aromatic polyimide or an aromatic polyamideimide can be produced by a usual method, for example, an isocyanate method, an acid chloride method, a low temperature solution polymerization method, a room temperature solution polymerization method, or the like.

Examples of raw materials used for the aromatic polyimide include the following. Examples of the acid component include pyromellitic acid, benzophenone-3, 3 ', 4, 4'-tetracarboxylic acid, biphenyl-3, 3', 4, '-tetracarboxylic acid, diphenylsulfone 3, 3', 4, 4'- Tetracarboxylic acid, diphenyl ether-3,3 ', 4,4'-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, naphthalene-1 Monoanhydrides such as 4,5,8-tetracarboxylic acid, dianhydrides, esterified products and the like can be used alone or as a mixture of two or more.
As the amine component, P-phenylenediamine, m-phenylenediamine, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3, 3 ' -Diaminobenzophenone, 3,4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 4,4′-diaminodiphenyl Hexafluoropropane, 3,3′-diaminodiphenylhexafluoropropane, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylhexafluoroisopropylidene, P-xylenediamine, m -Xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, O-tolidine, m-tolidine, 2,2'-bis (4-amino Phenyl) propane, 2,2′-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (
3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, bis [4- (3- Aminophenoxy) phenyl] hexafluoropropane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) ) Phenyl] hexafluoropropane, or the corresponding diisocyanate, or a mixture of two or more It is possible. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used.

  Raw materials used for aromatic polyamideimides include trimellitic anhydride, diphenyl ether-3, 3 ′, 4′-tricarboxylic acid anhydride, diphenylsulfone-3, 3 ′, 4′-tricarboxylic acid as acid components. Tricarboxylic acid anhydrides such as anhydride, benzophenone-3, 3 ′, 4′-tricarboxylic acid anhydride, naphthalene-1,2,4-tricarboxylic acid anhydride alone or as a mixture, and the amine component is a diamine similar to polyimide Or a diisocyanate alone or a mixture thereof. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used. Moreover, you may use the acid component illustrated as a raw material used for an aromatic polyimide other than the said acid component.

Particularly preferred polyimide resins are aromatic polyimides and aromatic polyamideimides soluble in organic solvents, and more preferably aromatic polyamideimides containing structural units represented by the following general formula (1) or (2).
In the structural unit, the preferable content of the general formula (1) is 5 mol% to 99 mol%, more preferably 20 mol% to 90 mol%, and still more preferably 40 mol% to 70 mol%. If the content of the general formula (1) is less than 5 mol%, the curl (warpage) or dimensional accuracy of the metal laminate is inferior, and if it is more than 99 mol%, the solubility of the organic solvent becomes poor. The workability of becomes worse.
One preferred structural unit is trimellitic anhydride (TMA), 3, 3, '4, 4'-benzophenone tetracarboxylic dianhydride (BTDA), 3, 3,', 4, 4 as the acid component. '-Biphenyltetracarboxylic dianhydride (BPDA) is used as an amine component, O-tolidine (or diisocyanate), the composition ratio of the acid component is TMA / BTDA / BPDA = 80-50 mol / 5-20 mol / 20-40 mol polyamideimide resin.
Further, the preferable content of the general formula (2) is 1 mol% to 99 mol%, more preferably 10 mol% to 90 mol%, and still more preferably 20 mol% to 80 mol%. If the content of the general formula (2) is less than 1 mol%, the curl (warp) or dimensional accuracy of the metal laminate is inferior. If it is more than 99 mol%, the solubility of the organic solvent becomes poor. It becomes poor in workability. One preferred structural unit is trimellitic anhydride (TMA), 3, 3, '4, 4'-benzophenone tetracarboxylic dianhydride (BTDA), 3, 3,', 4, 4 as the acid component. '-Biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic anhydride (PMA) are used as amine components and 1,5-naphthalenediamine (or diisocyanate) is used, and the composition ratio of the acid components is TMA / BTDA / BPDA / PMA = 10-40 mol / 20-50 mol / 10-10-30 mol / 5-15 mol polyamideimide resin.
Further, the same polymer may contain the structures of the general formulas (1) and (2), or the polymers having the structures of the general formulas (1) and (2) may be blended. I do not care.

（式中、Ｒ５、Ｒ６は同じであっても異なっていてもよく、それぞれ、水素もしくは炭素数１〜４のアルキル基を示す。）

(In the formula, R5 and R6 may be the same or different and each represents hydrogen or an alkyl group having 1 to 4 carbon atoms.)

Examples of the solvent for the polyimide resin solution include N-methyl-2-pyrrolidone, N, N′-dimethylformamide, N, N′-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane. Dimethyl sulfoxide, γ-butyrolactone, cyclohexanone, cyclopentanone, etc., preferably N-methyl-2-pyrrolidone. Some of these can be replaced with hydrocarbon organic solvents such as toluene and xylene, ether organic solvents such as diglyme, triglyme and tetrahydrofuran, and ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone.

  Any molecular weight of the polyimide resin can be used. For example, in N-methyl-2-pyrrolidone, it is preferable that the logarithmic viscosity at 30 ° C. is 0.3 to 2.5 dl / g, more preferably 1.0 to 2.0 dl / g in a polymer concentration of 0.5 g / dl. It is. If the logarithmic viscosity is less than 0.3 dl / g, the mechanical properties such as bendability and resistance to end tearing of the substrate are insufficient, and if it is greater than 2.5 dl / g, the adhesive strength is insufficient, and the solution viscosity is too low. Since it becomes high, the molding process becomes difficult. The number average molecular weight is preferably about 5000 to 100,000, and the molecular weight distribution is preferably about 2.0 to 5.0.

  Moreover, in the range which does not impair heat resistance and a thermal expansion coefficient in the aromatic polyimide used by this invention, and aromatic polyamideimide, adipic acid, azelaic acid, sebacic acid, cyclohexane-4,4, '-dicarboxylic acid, Aliphatic and alicyclic dicarboxylic acids such as butane-1,2,4-tricarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid , Polycarboxylic acids, and their monoanhydrides, dianhydrides, esterified products, and the like, and as an amine component, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, cyclohexane-1 Aliphatic and alicyclic diamines such as 1,4-diamine and diaminosiloxane or dii corresponding thereto Cyanate may be used alone or in combination of two or more. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used.

  In the present invention, other resins, organic compounds, and inorganic compounds are mixed for the purpose of improving various properties of the metal foil laminate, such as mechanical properties, electrical properties, slipperiness, and flame retardancy. Or you may make it react and use together. For example, lubricant (silica, talc, silicone, etc.), adhesion promoter, flame retardant (phosphorus, triazine, aluminum hydroxide, etc.), stabilizer (antioxidant, UV absorber, polymerization inhibitor, etc.), plating activity Agents, organic and inorganic fillers (talc, titanium oxide, fluoropolymer fine particles, pigments, dyes, calcium carbide, etc.), silicone compounds, fluorine compounds, isocyanate compounds, blocked isocyanate compounds, acrylic resins, urethane resins, Resins such as polyester resin, polyamide resin, epoxy resin, phenol resin and organic compounds, or these curing agents, inorganic compounds such as silicon oxide, titanium oxide, calcium carbonate, iron oxide, etc. are within the range not hindering the object of the present invention. Can be used together.

(Initial drying process)
In the present invention, a heat resistant resin solution is applied to a metal foil, and after initial drying (initial drying step), heat treatment and drying (hereinafter referred to as heat treatment / solvent removal step) are further performed to produce a metal foil laminate. Preferably, the amount of the residual solvent after the initial drying is not limited. For example, a laminate of 1% by weight to 50% by weight, preferably 10% by weight to 40% by weight, and more preferably 15% by weight to 30% by weight. Applicable. If the residual solvent ratio after the initial drying is less than 1%, the curl (warp) is large even after the subsequent heat treatment / desolvation step, resulting in poor dimensional accuracy. On the other hand, when the amount is more than 50% by weight, the resin coated surface is blocked, and the yield as a long product is deteriorated. The amount of residual solvent refers to the amount of solvent in the resin system including the solvent after coating and initial drying, and is represented by Equation (2).

The initial drying is preferably performed at a temperature 70 to 130 ° C. lower than the boiling point of the solvent used for the heat resistant resin solution. If the drying temperature is higher than (boiling point of solvent−70) ° C., even if the amount of residual solvent is 1% by weight or more, unevenness of the residual solvent in the thickness direction of the resin layer becomes large. Therefore, in the subsequent heat treatment / solvent removal step, the substrate tends to be curled and the productivity tends to decrease. On the other hand, when the temperature is lower than (boiling point of solvent−130) ° C., the drying time becomes longer and the productivity tends to decrease.
The preferred time for the initial drying varies depending on the temperature to be set and the thickness of the resin. For example, when the thickness of the resin is 25 μm (thickness after the heat treatment / solvent removal step) and the temperature is 100 ° C., 1 minute to 10 minutes It is preferably 3 minutes to 7 minutes, more preferably 4 minutes to 5 minutes. Further, when the temperature is 70 ° C. with the same resin thickness, it is 3 minutes to 15 minutes, preferably 5 minutes to 10 minutes, and more preferably 4 minutes to 8 minutes. If the drying time is less than the lower limit at each temperature, the drying property is insufficient, and the yield decreases due to blocking or the like. On the other hand, if the length is longer than the upper limit, curling (warping) is great even after the subsequent heat treatment / solvent removal step, resulting in poor dimensional accuracy.

The initial drying method can be performed by a conventionally known method such as a roll support method or a floating method. Moreover, it does not specifically limit as a coating method, A conventionally well-known method can be applied. The viscosity of the coating solution can be adjusted by a roll coater, knife coater, doctor blade coater, gravure coater, die coater, multilayer die coater, reverse coater, reverse roll coater, etc., and then applied directly to the metal foil. The suitable solution viscosity is preferably in the range of 1 to 1000 poise in B-type viscosity at 25 ° C. Although the density | concentration of a resin solution is based also on the molecular weight of resin, 5-30 weight% is preferable normally, More preferably, it is 10-20 weight%.
The coating width is not limited and can be set according to the width of the copper foil to be used. For example, it is 250 mm to 1000 mm.

(Heat treatment / solvent removal process)
In the present invention, the atmosphere during the heat treatment / desolvation is preferably performed under reduced pressure and / or in an inert gas atmosphere. When carried out in air, the resin layer is deteriorated or excessively cross-linked, and the curl of the substrate becomes large, or the mechanical properties of the resin layer are impaired. In addition, when heat treatment is performed in an air or oxygen atmosphere with a predetermined amount of an organic solvent such as N-methyl-2-pyrrolidone remaining, not only the mechanical properties of the resin layer but also the resin layer and the metal foil Adhesiveness decreases. The pressure is preferably about 10 mmHg or less, or in an inert gas atmosphere of 1000 ppm or less. More preferably, it is under a reduced pressure of about 5 mmHg or less, or in an inert gas atmosphere of 100 ppm or less. More preferably, it is under a reduced pressure of about 2 mmHg or less, or in an inert gas atmosphere of 50 ppm or less. When the pressure is lower than about 10 mmHg or under an inert gas atmosphere of 1000 ppm, the resin layer deteriorates and the curl increases.

In the present invention, the temperature and time conditions during the heat treatment and solvent removal can be arbitrarily set depending on the type of the long object. The temperature is a surface temperature of the metal laminate resin surface, and a treatment from 50 ° C. to 450 ° C. is suitable, and the conveyance speed can be changed from 1 m / min to 100 m / min in accordance with the treatment time. A preferable application range is 200 ° C. to 400 ° C., more preferably 250 ° C. to 350 ° C., and an arbitrary speed can be set for the treatment. When the temperature exceeds 450 ° C., the resin tends to deteriorate even in a nitrogen atmosphere. For example, in the case of a metal foil laminate in which a polyimide resin solution and / or its precursor is applied to a metal foil and initially dried, the laminate Characteristics, especially curl, dimensional accuracy, etc. are deteriorated. If it is less than 50 degreeC, drying efficiency is bad and productivity falls.
Strictly speaking, the preferred treatment time varies depending on the thickness of the laminated resin and the temperature, but for example, 0.5 minutes to 100 minutes, more preferably 3 minutes to 40 minutes, and even more preferably 5 minutes to 30 minutes. is there. When the heat treatment time is less than 0.5 minutes, the drying property is poor, and curling (warping), thermal dimensional accuracy, moisture absorption characteristics, adhesive strength, and reliability thereof are lowered. When the heat treatment time is longer than 100 minutes, the mechanical properties of the base film layer are deteriorated due to the thermal decomposition of the resin. In the present invention, a far infrared heater is used as the heating method. The type of the far infrared heater is not particularly limited, and an electric type, a steam type using steam or heat transfer oil as a heat source, an oil type, or a gas type using gas combustion heat as a heat source can be used. The wavelength range is not particularly limited and is in the far infrared range (5 μm to 1000 μm), but near infrared and / or infrared radiation can also be preferably used. In particular, from the viewpoint of drying efficiency, dimensional accuracy, and the like, treatment with a combination of near infrared rays (for example, 2 to 20 μm) is also preferable. As the drying furnace, a conventionally known hot air circulation heating path, electric furnace, IR heater, vacuum path, or the like may be used in combination.
The distance (irradiation distance) from the heater to the heating body (metal laminate) is not particularly limited as long as the surface temperature of the metal laminate becomes the above temperature. For example, it is 5 mm to 1000 mm. The heater position may be on the upper surface and / or the lower surface of the metal laminate. The power is not particularly limited, but is usually 1000 to 10 kW.
In addition, when the resin to be used is polyimide, imidation treatment may be necessary, but the heating method is not particularly changed. Polyimide can be formed by heat treatment and solvent removal as described above after the initial drying. However, in the case of a polyimide precursor, compared with a closed ring (soluble polyimide or polyamideimide), it is easier to thermally decompose, and from the viewpoint of thermal dimensional accuracy and heat resistance, in the stage before performing the treatment with far infrared rays, It is preferable to heat-process with a heating furnace, an electric furnace, IR heater, etc.

In the present invention, the base resin laminated on the metal foil may have a laminated structure of two or more layers. As the resin composition, the above-mentioned aromatic polyimide, aromatic polyamideimide and the like are preferable, and polyamideimide containing a repeating unit of the general formula (1) or the general formula (2) is more preferable. For example, the first layer in contact with the metal foil may be a composition containing the general formula (2), and the second layer laminated thereon may be a composition containing the general formula (1). In the general formula structural unit, the preferable content is 5 mol% to 99 mol%, more preferably 20 mol% to 90 mol%, and still more preferably 40 mol% to 70 mol in the case of the general formula (1). %. If the content of the general formula (1) is less than 5 mol%, the curl (warpage) and dimensional accuracy of the metal laminate is inferior, and if it is more than 99 mol%, the solubility of the organic solvent becomes poor. Workability deteriorates. One preferred structural unit is trimellitic anhydride (TMA), 3, 3, '4, 4'-benzophenone tetracarboxylic dianhydride (BTDA), 3, 3,', 4, 4 as the acid component. '-Biphenyltetracarboxylic dianhydride (BPDA) is used as an amine component, O-tolidine (or diisocyanate), the composition ratio of the acid component is TMA / BTDA / BPDA = 80-50 mol / 5-20 mol / 20-40 mol polyamideimide resin.
Further, the preferable content of the general formula (2) is 1 mol% to 99 mol%, more preferably 10 mol% to 90 mol%, and still more preferably 20 mol% to 80 mol%. When the content of the general formula (2) is less than 1 mol%, the metal laminate is inferior in curl (warp) and dimensional accuracy, and when it exceeds 99 mol%, the solubility of the organic solvent becomes poor. Sexuality gets worse. One preferred structural unit is trimellitic anhydride (TMA), 3, 3, '4, 4'-benzophenone tetracarboxylic dianhydride (BTDA), 3, 3,', 4, 4 as the acid component. '-Biphenyltetracarboxylic dianhydride (BPDA), pyromellitic anhydride (PMA) is used as the amine component, and 1,5-naphthalenediamine (or diisocyanate) as the amine component, and the composition ratio of the acid component is TMA / BTDA / BPDA / PMA = 10-40 mol / 20-50 mol / 10-10 mol / 5-15 mol polyamideimide resin. Of course, these can also be mixed and used.
The thickness ratio of the polyamideimide layer containing the repeating unit of the general formula (1) and the polyamideimide layer containing the repeating unit of the general formula (2) is preferably general formula (1) / general formula (2) = 1 to 100 μm. / 1 μm to 100 μm, preferably, general formula (1) / general formula (2) = 10
50 μm / 5 μm to 50 μm, more preferably, general formula (1) / general formula (2) = 20˜
30 μm / 10 μm to 30 μm. When the thickness of the general formula (2) is less than 1 μm, the adhesive strength and its reliability are lowered, and when it is thicker than 100 μm, the moisture absorption property is deteriorated. Further, if the thickness of the general formula (1) is less than 1 μm, the moisture absorption characteristics and dimensional accuracy are deteriorated, and if it is more than 100 μm, it is disadvantageous in terms of curling (warping). For example, the first layer in contact with the metal foil is a polyamideimide containing a repeating unit of the general formula (1), and the second layer laminated thereon is a polyamideimide containing a repeating unit of the general formula (2) You can also

  As a method of laminating two or more layers, the first layer can be applied, and after the initial drying, the second layer can be applied, initial drying, heat treatment and desolvation. Alternatively, the first layer may be coated, initially dried, heat-treated / desolvent, and then the second layer may be coated, initially dried, heat-treated / desolved. Furthermore, after the first layer is applied, the second layer may be applied, or the first layer and the second layer may be applied simultaneously, followed by initial drying, heat treatment and solvent removal. it can.

  In the method of heat treatment and drying in the far-infrared heating furnace in the present invention, the drying efficiency is high, and the drying speed and the drying efficiency in the thickness direction can be made constant. For example, in the case of a metal foil laminate, in addition to the residual solvent rate, curl, dimensional change rate, the adhesive strength, mechanical properties of the applied resin, physical properties such as moisture absorption properties, etc. should be uniform and good. Obtainable. In particular, when the long product of the present application is a metal foil laminate in which a polyimide resin solution and / or a precursor thereof is applied to a metal foil and initially dried, characteristics such as adhesive strength, reliability, and moisture absorption characteristics are conventionally known. Compared to the general drying method and those obtained under the drying conditions, it is greatly improved. This is a unique behavior achieved by the far-infrared heating method.

In the present invention, the continuous conveyance method of a long object at the time of heat treatment / solvent removal is preferably a roll-to-roll continuous conveyance, and a conventionally known method such as a roll support method or a floating method can be applied. It is a method. As shown in Fig. 1, the staggered transport system is a staggered arrangement of support rolls arranged at regular intervals, as shown in Fig. 1, with the upper and lower surfaces of the long object in contact with the rolls alternately. This is a method of conveying. The roll support method is a method in which the roll is conveyed in such a manner that the roll contacts only the upper surface or only the lower surface of the long object. By the staggered conveyance method, a long object can be conveyed in a fixed length in the TD direction (longitudinal direction and vertical direction), and curling (warping) and dimensional accuracy in the TD direction can be reduced. However, since the resin coated surface is usually conveyed in contact with the roll, blocking or the like occurs and cannot be conveyed, but in the present invention, the far infrared heat source, and in some cases, the combination of near infrared and far infrared Can be transported.
A preferable roll pitch is 50 mm or more and 10,000 mm or less, more preferably 100 mm or more and 5000 mm or less, and further preferably 200 mm or more and 1000 mm or less, but there is no particular limitation. When the roll pitch exceeds 10,000 mm, the curl becomes large depending on the long object. When the roll pitch is less than 50 mm, the transportability is inferior and the productivity tends to decrease. Also, the curl increases. There is no particular limitation on the height difference between rolls, but there is no particular limitation, although it tends to be good at 0 mm or more and 10,000 mm or less, preferably 10 mm or more and 5000 mm or less, and more preferably 100 mm or more and 1000 mm or less. If it is 10,000 mm or more, the curl becomes large depending on the type of the long object, and the productivity tends to be lowered.
Strictly speaking, the preferable range of the roll diameter is φ5 mm to φ500 mm, more preferably φ10 mm to φ100 mm, and still more preferably φ20 mm to φ60 mm, although it varies depending on the pitch. If the roll pitch is less than φ5 mm, the curl (warp) property is inferior unless the roll pitch is considerably narrowed, and if the roll pitch is larger than φ500 mm, the equipment becomes large, which is substantially different from the productivity and efficiency that are the objects of the present invention. Come. The material of the roll is not particularly limited, but SUS or the like with less thermal expansion can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not particularly limited by the examples. The evaluation method of the characteristic value in each example is as follows.

Logarithmic viscosity Dissolved in N-methyl-2-pyrrolidone so that the polymer concentration is 0.5 g / dl. The solution viscosity and solvent viscosity of the solution were measured at 30 ° C. using an Ubellose type viscosity tube. Calculated with the formula.

Glass transition point, coefficient of thermal expansion The glass transition point of the resin film layer obtained by etching away the metal foil of the flexible metal laminate of the present invention by TMA (Thermal Mechanical Analysis / manufactured by Rigaku Corporation) tensile load method was measured under the following conditions. did. The film was measured for a film that was once heated to 250 ° C. and then cooled to room temperature in nitrogen at a heating rate of 10 ° C./min. The thermal expansion coefficient was an average value from 100 ° C to 200 ° C.
Load: 1g
Sample size: 4 (width) x 20 (length) mm
Temperature increase rate: 10 ° C / min Atmosphere: Nitrogen

Residual solvent ratio JIS K5400 was calculated from the following equation under the drying conditions of 250 ° C. × 1 hr.

Curling of the substrate The curling rate of the curl of the metal-clad laminate was determined from JIS C6481 for a sample (sample size 100 mm × 100 mm) conditioned for 24 hours at 25 ° C. and 65% RH.

Solder heat resistance [Solder heat resistance (normal)]
A metal foil of a metal-clad laminate was etched by a subtractive method to produce a (35% ferric chloride solution) 1 mm wide circuit pattern (multiple patterns with a circuit width of 5 mm) at 25 ° C. and 65% ( The humidity was adjusted for 24 hours and the flux was washed, and then immersed in a jet solder bath at 320 ° C. for 20 seconds, and the presence or absence of peeling or swelling was observed with a microscope. ○ indicates that there is no peeling or swelling, and × indicates that peeling or swelling has occurred.
[Solder heat resistance (after humidification)]
A metal foil of a metal-clad laminate was etched by a subtractive method to produce a (35% ferric chloride solution) 1 mm wide circuit pattern (multiple patterns with a circuit width of 5 mm) at 40 ° C. and 90% ( The humidity was adjusted for 24 hours and the flux was washed, and then immersed in a jet solder bath at 320 ° C. for 20 seconds, and the presence or absence of peeling or swelling was observed with a microscope. ○ indicates that there is no peeling or swelling, and × indicates that peeling or swelling has occurred.

Dimensional change rate Measured in the MD direction and TD direction by IPC-FC241 using the B method (before and after etching) and the C method (before and after heat treatment at 150 ° C. for 30 minutes).

[Adhesive strength]
In accordance with IPC-FC241 (IPC-TM-650, 2.4.9 (A)), a circuit pattern (heat-resistant resin layer) and a circuit pattern (circuit width 1.2 mm) were prepared by a subtractive method. The adhesive strength of was measured. The samples were measured for two types of samples which were heat-treated at 200 ° C. for 10 days in a normal condition and a hot-air circulating drier.

[Hygroscopic rate]
A resin film having a length and a width of 50 ± 1 mm was measured by the following method. (If the cut surface of the sample is rough, it was finished smoothly with abrasive paper of P240 or higher as defined in JIS R 6252). Five samples were used for the measurement.
(1) The sample is allowed to stand for 24 hours in a thermostat kept at 50 ± 2 ° C.
(2) Leave the sample for 24 hours under the conditions of 25 ° C. and 90% RH so that the samples do not come into contact with each other (use the feather or brush to remove dust on the sample surface).
(3) Transfer the sample to a weighing bottle, seal it quickly with a lid, and leave it in a desiccator for about 1 hour at room temperature.
(4) The total weight of the weighing bottle and the sample is measured (W1), and then the sample is quickly taken out and the weight (W0) of only the weighing bottle is measured. (Or just leave the weighing bottle in the desiccator for more than 1 hour and measure its weight (W0) in advance)
(5) The sample in the weighing bottle is dried for 1 hour in a thermostat kept at 100 ± 5 ° C.
(6) Transfer the sample to a weighing bottle, seal it quickly with a lid, and leave it in a desiccator at room temperature for about 1 hour.
(7) The total weight of the weighing bottle and the sample is measured (referred to as W3), and then the sample is quickly taken out therefrom and the weight (W4) of only the weighing bottle is measured. (Or just leave the weighing bottle in the desiccator for 1 hour or more and measure its weight (W4) in advance)
(8) The moisture absorption rate WA (%) is calculated by the following formula.
WA = [{(W1-W0)-(W3-W4)} / (W1-W0)] × 100

Synthesis Example 1 Trimellitic anhydride 153.7 g (80 mol%), 3, 3 ′, 4, 4′-benzophenone tetracarboxylic dianhydride 40.3 g (12.5 mol%) in resin A synthesis reaction vessel 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 22.1 g (7.5 mol%), O-tolidine diisocyanate 264.3 g (100 mol%), diazabicycloundecene 1.0 g , And 2500 g of N-methyl-2-pyrrolidone (purity 99.9%) were added, the temperature was raised to 100 ° C. under a nitrogen stream, and the mixture was reacted at 100 ° C. for 5 hours. Next, 1031 g of N-methyl-2-pyrrolidone (polymer concentration: 10% by weight) was added and cooled to room temperature. The logarithmic viscosity of the obtained polymer was 1.4, and the solution viscosity at 25 ° C. (measured at 10 revolutions with a B-type viscometer) was 250 poise.

Synthesis Example 2 Synthesis of Resin B Trimellitic anhydride 38.4 g (20 mol%), 3, 3 ′, 4, 4′-benzophenone tetracarboxylic dianhydride 128.9 g (40 mol%), 3 in a reaction vessel 3 ', 4,4'-biphenyltetracarboxylic dianhydride 58.8 g (20 mol%), pyromellitic dianhydride 21.8 g (10 mol%), 1,5-naphthalene diisocyanate 210.2 g ( 100 mol%), 1.5 g of diazabicycloundecene and 2500 g of N-methyl-2-pyrrolidone were added, the temperature was raised to 100 ° C. over 1 hr, and the mixture was further reacted at 100 ° C. for 5 hr. Next, 840 g of NMP (polymer concentration 10% by weight) was added and cooled to room temperature. The logarithmic viscosity of the obtained polymer was 1.2, and the solution viscosity at 25 ° C. (measured at 10 revolutions with a B-type viscometer) was 180 poise.

Synthesis Example 3 Trimellitic anhydride 115.3 g (60 mol%), 3, 3 ′, 4, 4′-benzophenone tetracarboxylic dianhydride 32.2 g (10 mol%), 3 3 ′, 4,4′-biphenyltetracarboxylic dianhydride 88.3 g (30 mol%), O-tolidine diisocyanate 264.3 g (100 mol%), diazabicycloundecene 1.0 g, and N— 2500 g of methyl-2-pyrrolidone (purity 99.9%) was added, the temperature was raised to 100 ° C. under a nitrogen stream, and the mixture was reacted at 100 ° C. for 5 hours. Next, 1200 g of N-methyl-2-pyrrolidone (polymer concentration 10% by weight) was added, and the mixture was cooled to room temperature. The logarithmic viscosity of the obtained polymer was 1.6, and the solution viscosity at 25 ° C. (measured at 10 revolutions with a B-type viscometer) was 330 poise.

Synthesis Example 4 Synthesis of resin D 43 g (50 mol%) of p-phenylenediamine, 3200 g of N-methyl-2-pyrrolidone, and 80 g (50 mol%) of 4,4′-diaminodiphenyl ether were added and cooled to 5 ° C. Then, it stirred and melt | dissolved. Next, 236 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation) was gradually added and reacted at 5 ° C. for 2 hours (polymer concentration 10%). Subsequently, 1 g of 2-hydroxypyridine (2 mol% with respect to the monomer; manufactured by Nacalai Tesque) was added and reacted for 1 hour. The obtained polymer dope was light yellowish brown and transparent, and the polymer was dissolved in NMP. The logarithmic viscosity was 1.9 dl / g.

Example 1
The resin solutions obtained in Synthesis Examples 1 and 2 were subjected to solvent removal using a die coater on a treated surface of an electrolytic copper foil (USLP-SE-18 manufactured by Nihon Electrolysis Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively. Coating was continuously performed so that the thickness was 25 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
The metal-clad laminate thus obtained was subjected to a roll support system (roll pitch 200 mm, roll system 50 mmΦ) wavelength 5.6 to 1000 μm far infrared system (RtoR heat treatment apparatus heat manufactured by Noritake Engineering Co., Ltd.). The inside of the heating furnace was continuously conveyed. N2 flow rate 500L / min, oxygen concentration 100ppm, far infrared plate heater upper surface, lower surface arrangement, irradiation distance 100mm, capacity 225kW, heater dimensions 150mm x 700mm, temperature in heating furnace is 300 ° C (metal laminate surface temperature) The conveying speed was such that the drying time was 10 minutes. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 2
Using the die coater on the treated surface of the electrolytic copper foil (F2-WS manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively, the resin solutions obtained in Synthesis Examples 1 and 2 were removed. Was continuously coated to a thickness of 25 μm. Next, the film was continuously passed through a 20 m long flotation type drying furnace set at 100 ° C. at a speed of 3 m / min. The residual solvent ratio of the obtained metal laminate was 12% by weight.
The long product thus obtained is placed in a far-infrared heating furnace, and between the rolls as shown in FIG. 1 (roll pitch 200 mm, roll system 50 mmΦ, height difference between rolls 300 mm) is staggered. It was conveyed to. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), the oxygen concentration was 100 ppm, and the conveying speed was such that the drying time was 10 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 3
Thickness after solvent removal of the resin solutions obtained in Synthesis Examples 1 and 2 using a die coater on the treated surface of electrolytic copper foil (FT0-WS manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively. Was continuously coated to a thickness of 35 μm. Next, the film was continuously passed through a 20 m long flotation type drying furnace set at 100 ° C. at a speed of 3 m / min. The resulting metal laminate had a residual solvent ratio of 29% by weight.
The long product thus obtained is placed in a far-infrared heating furnace, and between the rolls as shown in FIG. 1 (roll pitch 200 mm, roll system 50 mmΦ, height difference between rolls 300 mm) is staggered. It was conveyed to. An aramid nonwoven fabric having a thickness of 100 μm was previously wound around the rolls conveyed in a staggered manner. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), the oxygen concentration was 100 ppm, and the conveying speed was such that the drying time was 10 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 4
The resin solution obtained in Synthesis Example 2 (resin B) was subjected to solvent removal using a die coater on the treated surface of an electrolytic copper foil (USLP-SE-12 manufactured by Nihon Denki Co., Ltd.) having a thickness of 12 μm and a width of 540 mm. Coating was continuously performed so that the thickness was 20 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
Next, the resin solution obtained in Synthesis Example 1 (resin A) was continuously coated on the coated surface of the laminate using a die coater so that the thickness after solvent removal was 20 μm, It was continuously passed through a 20 m long floating drying oven set at 120 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
The metal-clad laminate thus obtained was continuously conveyed in a far-infrared heating furnace of a roll support system (roll pitch 200 mm, roll system 50 mmΦ). The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), the oxygen concentration was 100 ppm, and the conveying speed was such that the drying time was 15 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 5
Thickness after solvent removal of the resin solutions obtained in Synthesis Examples 1 and 2 using a die coater on the treated surface of electrolytic copper foil (FT0-WS manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively. Was continuously coated to a thickness of 35 μm. Next, the film was continuously passed through a 20 m long flotation type drying furnace set at 100 ° C. at a speed of 3 m / min. The resulting metal laminate had a residual solvent ratio of 29% by weight.
The long support thus obtained is placed in a far-infrared heating furnace, the far-infrared type (RtoR type manufactured by Noritake Engineering Co., Ltd.) of the roll support type (roll pitch 200 mm, roll type 50 mmΦ). The inside of the heating furnace was continuously conveyed. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), and the conveying speed was such that the drying time was 10 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 6
Thickness after solvent removal using a die coater on the treated surface of an electrolytic copper foil (U-WZ manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 12 μm and a width of 540 mm. Was continuously coated so as to be 20 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
Next, the resin solution obtained in Synthesis Example 3 (resin C) was continuously coated on the coated surface of the laminate using a die coater so that the thickness after solvent removal was 20 μm. It was continuously passed through a 20 m long flotation type drying furnace at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
The metal-clad laminate obtained in this way is formed in a staggered manner between rolls (roll pitch 200 mm, roll system 50 mmΦ, height difference between rolls 300 mm) as shown in FIG. It was made to convey continuously in the heating furnace of engineering RtoR type heat treatment apparatus heat). An aramid nonwoven fabric having a thickness of 100 μm was previously wound around the rolls conveyed in a staggered manner. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), the oxygen concentration was 100 ppm, and the conveying speed was such that the drying time was 15 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 7
Thickness after solvent removal using a die coater on the treated surface of an electrolytic copper foil (U-WZ manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 12 μm and a width of 540 mm. Was continuously coated so as to be 10 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 20% by weight.
Next, the resin solution obtained in Synthesis Example 3 (resin C) was continuously coated on the coated surface of the laminate using a die coater so that the thickness after solvent removal was 30 μm, It was continuously passed through a 20 m long flotation type drying furnace at a speed of 5 m / min and wound up. The resulting metal laminate had a residual solvent ratio of 23% by weight.
The metal-clad laminate obtained in this way is formed in a staggered manner between rolls (roll pitch 200 mm, roll system 50 mmΦ, height difference between rolls 300 mm) as shown in FIG. The inside of the heating furnace of engineering RtoR type heat treatment apparatus heat) was continuously conveyed. An aramid nonwoven fabric having a thickness of 100 μm was previously wound around the rolls conveyed in a staggered manner. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), the oxygen concentration was 100 ppm, and the conveying speed was such that the drying time was 15 minutes. Other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Example 8
The resin solution D obtained in Synthesis Example 4 was treated with a die coater on an electrolytic copper foil having a thickness of 18 μm and a width of 540 mm (USLP-SE-18 manufactured by Nihon Denki Co., Ltd.), and the thickness after solvent removal was 25 μm. It was continuously coated so that Next, the film was continuously passed through a 20 m long floating drying oven set at 140 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
The metal-clad laminate thus obtained is continuously fed in the heating furnace of the far-infrared system (RtoR heat treatment device manufactured by Noritake Engineering Co., Ltd.) of the roll support system (roll pitch 200 mm, roll system 50 mmΦ). It was conveyed to. The temperature in the heating furnace and the drying time were 10 minutes at 300 ° C. (metal laminate surface temperature) and 10 minutes at 350 ° C. (metal laminate surface temperature), and other conditions were the same as in Example 1. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Comparative Example 1
Thickness after solvent removal of the resin solutions obtained in Synthesis Examples 1 and 2 using a die coater on the treated surface of electrolytic copper foil (FT0-WS manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively. Was continuously coated so as to be 30 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 32% by weight.
The long product thus obtained is continuously transported between roll support type rolls arranged in a hot air circulation type heating furnace (inter-roll pitch 200 mm, roll system 50 mmΦ, inter-roll height difference 300 mm). I let you. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), and the conveying speed was such that the drying time was 15 minutes. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

Comparative Example 2
The resin solutions obtained in Synthesis Examples 1 and 2 were subjected to solvent removal using a die coater on a treated surface of an electrolytic copper foil (USLP-SE-18 manufactured by Nihon Electrolysis Co., Ltd.) having a thickness of 18 μm and a width of 540 mm, respectively. Coating was continuously performed so that the thickness was 25 μm. Subsequently, the film was continuously passed through a 20 m long floating drying oven set at 100 ° C. at a speed of 5 m / min and wound up. The residual solvent ratio of the obtained metal laminate was 25% by weight.
The long product thus obtained is continuously transported between roll support type rolls arranged in a hot air circulation type heating furnace (inter-roll pitch 200 mm, roll system 50 mmΦ, inter-roll height difference 300 mm). I let you. The temperature in the heating furnace was 300 ° C. (metal laminate surface temperature), and the conveying speed was such that the drying time was 15 minutes. The solvent in the coating film of the obtained metal-clad laminate was completely removed, and the characteristics were as shown in Tables 1 and 2.

    The present invention relates to a method for treating a long object, and more specifically, drying a long object after impregnating or coating a long object such as a film, a textile fabric, a sheet, and a metal foil with water or an organic solvent solution, and The present invention relates to a method for efficiently performing a heat treatment with a high yield and a method for treating a long object having excellent performance such as dimensional stability and moisture absorption characteristics. In particular, the present invention relates to a method for producing a flexible metal-clad laminate obtained by applying polyimide resin or a precursor thereof to a metal foil and drying, which is useful as a flexible printed wiring board.

Staggered transport system

Claims (4)

In the continuous processing method of a long thing including the process of carrying and heat-treating a long thing continuously, this heat treatment is a far-infrared heating system, The long thing processing method characterized by the above-mentioned. The long object processing method according to claim 1, wherein the conveyance is a staggered conveyance system. 3. The long object processing method according to claim 1, wherein the long object is a metal foil laminate obtained by applying a polyimide resin solution or / and a precursor thereof to a metal foil and initially drying the metal foil. The long thing obtained by the long thing processing method in any one of Claims 1-3.

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