JP2009286984A - Method for manufacturing polyimide-based film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method for manufacturing a polyimide-based film which has a superior productivity and also gives a polyimide-based film excellent in heat resistance, durability, dimensional stability and appearance. <P>SOLUTION: The method for manufacturing a polyimide-based film involves manufacturing the polyimide-based film from a laminate obtained by drying a resin solution containing the polyimide-based film coated on a carrier and containing not less than 5 wt.% and not more than 40 wt.% of the residual solvent, and is provided with a step of drying and heat-treatment with super-heated steam. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a polyimide resin film from a resin solution containing a polyimide resin, and more particularly to a method for producing a polyimide resin film comprising a step of drying and heat treatment using superheated steam.

The polyimide film has excellent properties such as heat resistance, cold resistance, mechanical strength, electrical insulation, and chemical resistance. Polyimide films are used for electric insulation materials for electric wires, base films for flexible printed wiring boards, films for tape automated bonding (TAB), and the like.
A polyimide resin is produced by obtaining a polyamic acid from a tetracarboxylic dianhydride and a diamine compound and imidizing it with a ring-closing reaction. The imidization includes a chemical ring closure method in which dehydration is performed using a dehydrating agent and a catalyst, and a thermal ring closure method in which dehydration is performed by heating. Moreover, the method of using both together is also known. Organic solvent-soluble polyimide resins that improve the solubility of polyimide resins by using raw materials that have bulky substituents in the side chain and materials that have increased solubility in organic solvents in addition to the method using polyamic acid Are known. Substituting an amide bond with an amide bond increases the solubility in an organic solvent.
Methods for producing a polyimide film include a method in which a polyamic acid solution is applied and dried on a support and then imidized, and a method in which an organic solvent-soluble polyimide resin solution is applied and dried. Polyimide films are generally colored yellow-brown to black-brown, but those made colorless and transparent using alicyclic materials and those made colorless and transparent using diaminodiphenyl sulfone compounds are also known. Yes. Furthermore, it is also known that transparency is improved by using a raw material containing fluorine.
As a solvent for the polyimide resin, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, γ-butyrolactone, phenol, cresol, and the like are used. In particular, amide solvents such as N-methyl-2-pyrrolidone and N, N-dimethylacetamide have low vapor pressure due to intermolecular hydrogen bonding, and the diffusion of the solvent is poor due to the high glass transition temperature of the heat-resistant resin. Yes, it tends to remain in the coating film. Residual solvent causes a decrease in heat resistance and a decrease in dimensional stability. If the drying temperature or heat treatment temperature is too high in order not to leave the solvent, discoloration of the amide solvent occurs, and the appearance of the colorless and transparent polyimide film is deteriorated. In order to avoid adverse effects caused by an increase in drying and heat treatment temperature and not to leave a solvent, drying and heat treatment are performed over time in the film forming process. Therefore, there is a problem in productivity.
Superheated steam refers to steam that has been heated by heating saturated steam at normal pressure. Since superheated steam has a radiant heat energy significantly higher than that of normal steam at a temperature of 150 ° C. or higher, the substance can be heated in a short time. Superheated steam is used for cooking food, washing resin products and metal products, sterilizing food containers, or treating soil. The use of superheated steam as a heating heat source is not very popular except for cooking food.
However, when superheated steam is compared with general heated air, it has the following characteristics.
(1) Since the heat capacity is larger than that of heated air, rapid heating is possible.
(2) Since it has a constant-pressure specific heat about twice that of heated air, it has excellent heating capacity.
(3) Since it has latent heat energy, its enthalpy is larger than that of heated air.
(4) Although heat transfer by air is limited to convection heat transfer, superheated steam has a high heat efficiency because of the combined heat transfer action from convection heat transfer, radiant heat transfer, and condensation heat transfer.
It is known in Patent Documents 1 to 6 and Non-Patent Document 1 to dry superheated steam as a heating heat source. Patent Documents 1 to 5 propose a method of drying moisture of wet paper mainly composed of cellulose fibers with superheated steam. Patent Document 6 proposes application of superheated steam to a polyolefin film, a polyamide film, a coating film on a polyester film, or a wet cellophane film. Non-Patent Document 1 shows characteristics and utilization examples of superheated steam.
Japanese Patent No. 2907265 Japanese Patent No. 2907266 Japanese Patent No. 3007542 Japanese Patent Publication No. 2003-41495 Japanese Patent Publication No. 2005-15924 Japanese Patent Publication No. 2007-276283 Superheated steam technology assembly NTS Corporation (issued in 2005)

  An object of the present invention is to provide a production method in which the heating and drying efficiency is enhanced by using superheated steam in producing a polyimide film by a casting method. Furthermore, it is providing the manufacturing method of the polyimide-type film which does not have the bad effect by a residual solvent or overheating.

    The inventors of the present invention have arrived at the present invention as a result of intensive studies on a method for producing a polyimide film. That is, the present invention provides a laminate comprising a coating layer containing a residual solvent obtained by coating and drying a resin solution containing a polyimide resin on a support made of a metal or a heat-resistant resin in an amount of 5 wt% or more and 40 wt% or less. Is a process for drying and heat-treating using superheated steam, and a process for peeling the polyimide resin layer from the support.

  According to the present invention, a polyimide film can be produced efficiently. In addition, the polyimide film obtained according to the present invention can improve the adverse effects caused by the coloration of the amide solvent, which is likely to occur when a colorless and transparent resin is used.

Examples of the polyimide resin used in the present invention include a polyimide precursor resin, a solvent-soluble polyimide resin, and a polyamideimide resin. The polyimide resin can be polymerized by a usual method. For example, a method of obtaining a polyimide precursor solution by reacting tetracarboxylic dianhydride and diamine in a solution at low temperature, and a method of obtaining a solvent-soluble polyimide solution by reacting tetracarboxylic dianhydride and diamine in a high temperature solution. There are a method using isocyanate as a raw material and a method using acid chloride as a raw material.
The raw materials used for the polyimide precursor resin and the solvent-soluble polyimide resin include the following. Examples of acid components include pyromellitic acid, benzophenone-3,3 ', 4,4'-tetracarboxylic acid, biphenyl-3,3', 4,4'-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 , Monoanhydrides, dianhydrides, esterified products such as naphthalene-1,4,5,8-tetracarboxylic acid, hydrogenated pyromellitic acid, hydrogenated biphenyl-3,3 ', 4,4'-tetracarboxylic acid Etc. 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'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 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'-diaminodiphenylhexafluoropropane, 3,3'-diaminodiphenylhexafluoropropane, 4,4'-diaminodiphenylmeta 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylhexafluoroisopropylidene, p-xylenediamine, m-xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6- Naphthalenediamine, 2,7-naphthalenediamine, o-tolidine, 2,2'-bis (4-aminophenyl) 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] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3- Aminophenoxy) phenyl] hexafuro Propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, One or a mixture of two or more of cyclohexyl-1,4-diamine, isophoronediamine, hydrogenated 4,4′-diaminodiphenylmethane, or the corresponding diisocyanate compounds can be used. 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 polyamideimide resin include trimellitic anhydride, diphenyl ether-3,3 ', 4'-tricarboxylic acid anhydride, diphenylsulfone-3,3', 4'-tricarboxylic acid anhydride, benzophenone as acid component Tricarboxylic acid anhydrides such as -3,3 ′, 4′-tricarboxylic acid anhydride, naphthalene-1,2,4-tricarboxylic acid anhydride, and hydrogenated trimellitic acid anhydride may be used alone or as a mixture. In addition to tricarboxylic acid anhydrides, tetracarboxylic acids mentioned in the polyimide resin, their anhydrides, dicarboxylic acids and the like can also be used in combination. Examples of the amine component include diamines mentioned for polyimide resins, or diisocyanates alone or as a mixture. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used.
The solvent of the polyimide resin solution used in the present invention is that the solubility of the polyimide resin is good, the formation of water and an azeotropic compound in the gas layer, and the compatibility with water is the effect of superheated steam To increase. Further, if the solvent is compatible with water, the evaporated solvent can be easily recovered, which is industrially advantageous. Specifically, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane, dimethyl sulfoxide, Examples thereof include γ-butyrolactone, cyclohexanone, and cyclopentanone. Of these, N-methyl-2-pyrrolidone and N, N-dimethylacetamide are preferred. Further, a solvent such as toluene, xylene, diglyme, tetrahydrofuran, methyl ethyl ketone, etc. may be added as long as the solubility is not inhibited.
In the production method of the present invention, before applying drying / heat treatment with superheated steam, the coating layer containing the polyimide resin contains a solvent in the range of 5 wt% to 40 wt%. When the residual solvent is less than 5% by weight, the strain due to the internal stress is large, and the internal stress cannot be completely relieved by heating with superheated steam. Therefore, curl and heat resistance durability are inferior. On the other hand, when the amount is more than 40% by weight, the transparency of the coating layer may be lowered due to the superheated steam treatment, and surface irregularities are generated. In order to make a residual solvent into said range, you may make it dry at another process, before performing a superheated steam process with the apparatus of this invention. Of course, the drying process and the superheated steam treatment process may be continued.
Examples of the support used in the present invention include metal foils and sheets such as stainless steel, aluminum, copper, and iron, and films and sheets of polyimide and thermosetting resins. Among these, a stainless steel foil, a stainless steel sheet, an aluminum foil, an aluminum sheet, a film or a sheet having improved heat resistance by introducing a skeleton such as polyimide, especially benzoxazole, is desirable.
In the present invention, other resins and various additives may be blended or reacted for the purpose of improving various properties of the polyimide film, for example, mechanical properties, electrical properties, slipperiness, flame retardancy, releasability, etc. It doesn't matter. Examples of the lubricant include silica, talc, and silicone compounds. Examples of the flame retardant include phosphorus-containing compounds, triazine compounds, aluminum hydroxide, and magnesium hydroxide. Examples of the releasing agent include higher alcohols, higher fatty acids, higher fatty acid esters, higher fatty acid metal salts and the like. Also included are stabilizers such as antioxidants and UV absorbers, plating activators, and organic and inorganic fillers. Moreover, you may mix | blend other resins, such as hardening | curing agents, such as an isocyanate compound, an epoxy resin, and a phenol resin, a polyester resin, a polyurethane resin, and a polyamide resin.
In the production method of the present invention, superheated steam having a heat capacity and specific heat larger than air is used as a heat source for drying and heat treatment. In the drying / heat treatment furnace, superheated steam may be circulated or discharged. The optimum range of the temperature of superheated steam varies depending on the resin composition and the type of solvent.
The production method of the present invention will be described. After the polyimide resin solution is applied to the support and primarily dried, it is further dried and heat-treated with superheated steam at a higher temperature. By adjusting the residual solvent ratio in the coating layer after primary drying to a range of 5 to 40%, preferably 15 to 30%, the influence of volume shrinkage due to evaporation of the solvent and the influence on surface smoothness should be reduced. This is effective in improving curl due to a decrease in residual stress. The primary drying conditions are preferably 60 to 150 ° C. and 1 to 10 minutes.
After primary drying, drying and heat treatment with superheated steam is performed. When the polyimide resin is a polyimide precursor resin, a heat treatment involving an imidization reaction is performed. When the polyimide resin is a solvent-soluble polyimide resin or polyamideimide resin, the solvent is removed by heating. The treatment with superheated steam may be used in combination with hot air drying or infrared or far infrared drying. The temperature of the superheated steam used is in the range of 150 to 400 ° C, preferably 200 to 350 ° C. If the temperature is 150 ° C. or less, there is a possibility that a sufficient effect cannot be obtained. If the temperature is 400 ° C. or higher, the residual solvent may bump up and a good laminate may not be obtained, and the resin may be deteriorated. Since the temperature becomes higher than 150 ° C. during the drying heat treatment, the solvent used may be denatured, and the color of the film may be changed by the modified product of the colored solvent. Although superheated steam is almost completely oxygen-free, if air contamination occurs, it is necessary to lower the oxygen concentration as necessary. In order to suppress discoloration of the film, it is desirable to reduce the oxygen concentration to 5% or less, preferably 0.5% or less.
After the heat treatment, it is peeled off from the support. In order to facilitate peeling, it is desirable that the surface of the support is subjected to a release treatment in advance, or a release agent is added to the polyimide resin solution.

In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to the examples. In addition, the measured value described in the Example is measured by the following method.
Residual solvent: The residual solvent concentration in the polyimide film was determined by weight reduction from 150 ° C. to 350 ° C. using a differential thermothermal gravimetric simultaneous measurement apparatus EXSTAR6000TG / DTA manufactured by Seiko Instruments Inc.
Solder heat resistance: Polyimide film and copper foil (electrolytic copper foil 35 μm made by Mitsui Mining Co., Ltd.) copolymerized polyester resin (Byron 550 made by Toyobo Co., Ltd.) Epoxy resin (Epibis type epoxy 828 made by Japan Epoxy Resin) and polyisocyanate compound It bonded together with the adhesive which consists of (Nippon Polyurethane Co., Ltd. coronate L). Curing treatment was performed at 80 ° C. for 2 days. The copper foil of the obtained copper-clad laminate was etched by a subtractive method to create a circuit pattern with a width of 1 mm. After humidity conditioning at 40 ° C. and 65% RH for 24 hours and flux cleaning, the sample was immersed in a solder bath at 280 ° C. for 20 seconds and observed for peeling or swelling with a microscope. The thing in which abnormality was not seen was set as (circle), and the thing in which peeling and the swelling were seen were set as x.
Dimensional change: The dimensional change rate in the MD and TD directions by heat treatment at 150 ° C. for 30 minutes was determined by IPC-FC241 (IPC-TM-650, 2.2.4 (c)) using a polyimide film. The table shows the larger dimensional change rate in the MD and TD directions.

Synthesis example 1
In a reaction vessel, 192 g of trimellitic anhydride, 211 g of 3,3′-dimethyl-4,4′-biphenyl diisocyanate, 35 g of 2,4-tolylene diisocyanate, 0.5 g of sodium methylate and N-methyl-2-pyrrolidone 5 kg was added, the temperature was raised to 150 ° C. over 1 hour, and the reaction was further carried out at 150 ° C. for 5 hours. The obtained polyamideimide resin had a logarithmic viscosity of 1.6 and a glass transition temperature of 320 ° C.

Synthesis example 2
850 g of N, N-dimethylacetamide, 47.7 g of 4,4′-diamino-2,2′-dimethylbiphenyl and 20.7 g of 4,4′-bis (3-aminophenoxy) biphenyl are put into a reaction vessel and stirred. And dissolved. Next, 80.4 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added, and stirring was continued at room temperature for 5 hours to obtain a polyimide precursor.

Synthesis example 3
Add 158 g of hydrogenated trimellitic anhydride, 33 g of terephthalic acid, 261 g of 3,3′-dimethyl-4,4′-biphenyl diisocyanate, 0.5 g of lithium iodide and 2.5 kg of N, N-dimethylacetamide to the reaction vessel, The temperature was raised to 150 ° C. over 1 hour, and further reacted at 150 ° C. for 5 hours. The obtained polyamideimide resin had a logarithmic viscosity of 1.2 and a glass transition temperature of 310 ° C.

<Example 1>
The polyamideimide solution prepared in Synthesis Example 1 was applied by hand to an aluminum foil (50 μm made by Toyo Aluminum) previously treated with a fluorine-based mold release agent using an applicator so that the thickness after drying was 25 μm, and 100 ° C. And primary drying with hot air for 5 minutes. Furthermore, using a steam superheater ("DHF Super-Hi 10" manufactured by Daiichi High Frequency Industrial Co., Ltd.) as a superheated steam generator, drying and heat treatment were performed in a drying and heat treatment furnace for supplying 10 kg / hour of superheated steam. After peeling from the aluminum foil, the amount of residual solvent, solder heat resistance, and dimensional change rate were measured. The results are shown in Table-1.

<Example 2>
In the same manner as in Example 1, the polyimide precursor solution prepared in Synthesis Example 2 was hand-applied to a release-treated aluminum foil using an applicator so that the thickness after dry ring closure was 25 μm, and 5 ° C. at 120 ° C. Primary drying with hot air for minutes. Furthermore, using a steam superheater ("DHF Super-Hi 10" manufactured by Daiichi High Frequency Industrial Co., Ltd.) as a superheated steam generator, drying and heat treatment were performed in a drying and heat treatment furnace for supplying 10 kg / hour of superheated steam. The treatment conditions were that the temperature was raised from 120 ° C. to 320 ° C. over 15 minutes, followed by superheated steam treatment at 320 ° C. After peeling from the aluminum foil, the amount of residual solvent, solder heat resistance, and dimensional change rate were measured. The results are shown in Table-1.

<Example 3>
Stearic acid is added to the polyamideimide solution prepared in Synthesis Example 3 in an amount of 0.2% by weight, and this is applied by hand to a 100 μm thick stainless steel foil so that the thickness after drying is 25 μm. It was applied and primary dried with hot air at 100 ° C. for 5 minutes. Furthermore, using a steam superheater ("DHF Super-Hi 10" manufactured by Daiichi High Frequency Industrial Co., Ltd.) as a superheated steam generator, drying and heat treatment were performed in a drying and heat treatment furnace for supplying 10 kg / hour of superheated steam. After peeling from the stainless steel foil, the amount of residual solvent and the dimensional change rate were measured. The results are shown in Table-1.

<Comparative Example 1>
As in Example 1, the polyamideimide solution prepared in Synthesis Example 1 was preliminarily treated with a fluorine-based mold release agent using an applicator so that the thickness after drying was 25 μm. , Applied by hand, and primary dried with hot air at 100 ° C. for 5 minutes. Further, as a drying and heat treatment, a drying heat treatment was performed in a hot air circulation drying and heat treatment furnace. After peeling from the aluminum foil, the amount of residual solvent, solder heat resistance, and dimensional change rate were measured. The results are shown in Table-1.

<Comparative Example 2>
The polyamideimide solution prepared in Synthesis Example 1 was hand-coated on a release-treated aluminum foil using an applicator so that the thickness after drying was 25 μm, and was primarily dried with hot air at 280 ° C. for 5 minutes. Furthermore, using a steam superheater ("DHF Super-Hi 10" manufactured by Daiichi High Frequency Industrial Co., Ltd.) as a superheated steam generator, drying and heat treatment were performed in a drying and heat treatment furnace for supplying 10 kg / hour of superheated steam. The aluminum foil was peeled off, and the residual solvent amount, solder heat resistance, and dimensional change rate were measured. Further, the curl is larger than that of Example 1 or Comparative Examples 1 and 3. The results are shown in Table-1. The residual solvent amount before drying and heat treatment with superheated steam was 4.1%.

<Comparative Example 3>
The polyamideimide solution prepared in Synthesis Example 1 was hand-coated on a release-treated aluminum foil using an applicator so that the thickness after drying was 25 μm, and was primarily dried with hot air at 50 ° C. for 3 minutes. Furthermore, using a steam superheater ("DHF Super-Hi 10" manufactured by Daiichi High Frequency Industrial Co., Ltd.) as a superheated steam generator, drying and heat treatment were performed in a drying and heat treatment furnace for supplying 10 kg / hour of superheated steam. After peeling from the aluminum foil, the amount of residual solvent, solder heat resistance, and dimensional change rate were measured. The polyimide layer was opaque. The results are shown in Table-1. The residual solvent amount before drying and heat treatment with superheated steam was 45%.

<Comparative Example 4>
The polyimide precursor solution prepared in Synthesis Example 2 was hand-coated on an aluminum foil that had been subjected to mold release treatment using an applicator so that the thickness after dry ring closure was 25 μm, and was primarily dried at 120 ° C. for 5 minutes. Furthermore, using a hot air circulating furnace, the temperature was raised from 120 ° C. to 350 ° C. over 15 minutes, and then hot air drying at 350 ° C. was performed. No heat treatment with superheated steam was performed. After peeling from the aluminum foil, the amount of residual solvent, solder heat resistance, and dimensional change rate were measured. The results are shown in Table-1.

<Comparative Example 5>
Stearic acid is added to the polyamideimide solution prepared in Synthesis Example 3 in an amount of 0.2% by weight, and this is applied by hand to a 100 μm thick stainless steel foil so that the thickness after drying is 25 μm. It was applied and primary dried with hot air at 100 ° C. for 5 minutes. Furthermore, drying and heat treatment were performed using a hot air circulating furnace. After peeling from the stainless steel foil, the amount of residual solvent and the dimensional change rate were measured. The results are shown in Table-1.

  The present invention relates to a simple method for producing a polyimide film. By using this production method, productivity can be improved, and further, a polyimide film excellent in heat resistance, durability, dimensional stability, and appearance can be obtained. Can be provided.

Claims (1)

  A laminate containing 5 wt% or more and 40 wt% or less of a residual solvent obtained by applying and drying a resin solution containing a polyimide resin on a support made of a metal or a heat resistant resin, with superheated steam The manufacturing method of the polyimide-type film characterized by including the process of using and drying and heat-processing, and the process of peeling a polyimide-type resin layer from this support body.