JP2010201871A - Method of manufacturing polyimide resin mold and polyamic acid film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of easily manufacturing a polyimide resin mold having a high dimensional stability, and having a small thickness. <P>SOLUTION: This manufacturing method of the polyimide resin mold is provide for forming imide by setting a polyamic acid film having a tensile elastic modulus of 900-1,500 MPa and an elongation of 30-60% in a mold. The polyamic acid film is desirably dried until a residual solvent quantity becomes 5-18 mass% by applying a solution of a polyamic acid on a support. A desirable thickness of the polyimide resin mold provided by this manufacturing method is 10-500 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a polyimide resin molded body. Moreover, this invention relates to the polyamic acid film used exclusively for manufacture of a polyimide resin molding.

  Conventionally, polyimide resin materials have been used in a wide range of fields from the aerospace field to the electrical and electronic materials field because of their high mechanical strength and heat resistance. This polyimide resin material is molded into various shapes, for example, a cylindrical shape, a cup shape, an umbrella shape, a dome shape, a corrugated shape, and the like according to the application.

  As a method for producing a polyimide resin molded body, for example, there is simply a method in which a solution of polyamic acid, which is a polyimide precursor, is directly applied to a mold and imidized. According to the manufacturing method, a thin molded article having good shape following property can be obtained, and tearing and wrinkle are hardly generated. However, there is a problem that the film thickness may be thinned or thickened at a portion having a small radius of curvature or a corner portion of the mold, and the dimensional stability is lacking particularly in a complicated shape.

  On the other hand, Patent Document 1 proposes to produce a polyimide resin molded body having excellent dimensional stability by pre-heating high temperature and high pressure molding of a two-layer powder of crystalline polyimide and amorphous polyimide. is doing. However, this method has a problem that the process is complicated and it is difficult to obtain a molded product having a small thickness.

Japanese Patent No. 4010594

  In view of the above problems, an object of the present invention is to provide a method capable of easily producing a molded article of polyimide resin having high dimensional stability and small thickness. It is another object of the present invention to provide a polyamic acid film as a raw material for a molded body, which can easily produce a molded body of polyimide resin having high dimensional stability and a small thickness.

  The present invention that has achieved the above object is a method for producing a polyimide resin molded body, in which a polyamic acid film having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60% is set in a mold and imidized. The polyamic acid film is preferably one obtained by applying a polyamic acid solution on a support and drying it until the residual solvent amount is 5 to 18% by mass. The suitable thickness of the polyimide resin molding obtained by the said manufacturing method is 10-500 micrometers.

  Another aspect of the present invention is a polyamic acid film for producing a polyimide resin molded body having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60%.

  According to the present invention, since a uniform film having a small thickness can be used as a molding material, it is possible to easily produce a polyimide resin molded body having a high dimensional stability and a small thickness. The resulting polyimide resin molded article has high mechanical strength, heat resistance, etc. specific to the polyimide resin.

  In the present invention, a polyamic acid film having a tensile modulus of 900 to 1500 MPa and an elongation of 30 to 60% is used. When the tensile modulus is less than 900 MPa, the film becomes brittle and breakage or the like may occur. When the tensile elastic modulus exceeds 1500 MPa, the force required to fix the film to the mold becomes high, and when the drawing amount is large, wrinkles are likely to occur. On the other hand, when the elongation is less than 30%, it becomes difficult for the film to follow the acute angle surface of the mold, and it becomes difficult to obtain a molded body having a desired shape. If the elongation exceeds 60%, the film tends to be stretched unevenly when set in a mold, and the film thickness may eventually vary. The tensile elastic modulus is preferably 1000 to 1400 MPa. The elongation is preferably 35 to 55%.

  The tensile modulus and elongation can be determined using a tensile tester according to JIS K6251 (2004), for example. In the present invention, “elongation” means “elongation at break”.

  The solvent content of the polyamic acid film is not particularly limited as long as the film has a tensile modulus of 900 to 1500 MPa and an elongation of 30 to 60%, but is preferably 5 to 18% by mass. When the film contains a solvent in such a range, the film tends to have a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60%. When the solvent content of the film is less than 5% by mass, the film becomes rigid and tends to be difficult to follow the mold. If it exceeds 18% by mass, wrinkles are likely to occur on the film surface, and the film may shrink and deform greatly due to the volatilization of the solvent.

  Although there is no restriction | limiting in particular as a solvent which the said polyamic acid film contains, The solvent used for the synthesis | combination of a polyamic acid is preferable. As such a solvent, a polar solvent is preferable, and specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N Examples include -dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone and the like. These may be contained alone or in combination of two or more. In addition to these polar solvents, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like may be mixed alone or in combination.

  The polyamic acid constituting the polyamic acid film has a structure obtained by polymerization reaction of acid dianhydride and diamine. Preferable examples of acid dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid A dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride etc. are mentioned. Examples of diamines include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3 '-Diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine, 3, Examples include 3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, and the like.

  The thickness of the polyamic acid film is preferably set to a value such that the thickness of the polyimide resin molded body is 10 to 500 μm. When the thickness of the molded body is less than 10 μm, the rigidity is insufficient, and folding and buckling are likely to occur. On the other hand, if it exceeds 500 μm, the amount of shrinkage at the time of molding is large, it becomes difficult to follow a fine uneven shape, and cracks are likely to occur. Further, the thickness uniformity is preferably as high as possible, but may be appropriately selected according to the dimensional stability required for the molded body.

  The polyamic acid film is preferably produced by applying a polyamic acid solution on a support and drying it until the residual solvent amount is 5 to 18% by mass. Here, a polyamic acid film having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60% can be easily obtained by appropriately adjusting the residual solvent amount within this range depending on the type of polyamic acid.

  The solution of polyamic acid can be obtained by reacting the above acid dianhydride and diamine in the above solvent. In addition, since polyamic acid is hydrolyzed by the presence of water to reduce the molecular weight, the synthesis and storage of polyamic acid are preferably performed in an anhydrous environment. The monomer concentration during the reaction (the total concentration of acid dianhydride and diamine in the solvent) may be appropriately determined according to various conditions, but is preferably 5 to 30% by mass. The reaction temperature is preferably set to 80 ° C or lower, more preferably 5 to 50 ° C. The reaction time is preferably 0.5 to 10 hours.

  The viscosity of the polyamic acid solution is, for example, 10 to 10000 poise (1 to 1000 Pa · s), preferably 50 to 5000 poise (5 to 500 Pa · s) (B-type viscometer, 23 ° C.). If the viscosity is less than 10 poise, so-called sagging or repelling of the coating layer is likely to occur, and it may be difficult to obtain a uniform coating thickness. On the other hand, when it exceeds 10,000 poise, it is necessary to apply a high pressure when discharging at the time of application, and the leveling property and defoaming property tend to be inferior.

  What is necessary is just to select what has chemical resistance with respect to a polyamic acid, for example, a glass plate etc. as a support body. In addition, in order to increase the uniformity of the film thickness, a support having a high surface smoothness may be selected.

  The amount of the polyamic acid solution applied to the support is preferably set to such an amount that the final molded body has a thickness of 10 to 500 μm.

  The drying conditions of the polyamic acid solution were the temperature, wind speed, and time conditions so that the residual solvent amount was such that the tensile modulus of the polyamic acid film after drying was 900 to 1500 MPa and the elongation was 30 to 60%. Control is sufficient.

  The method for setting the polyamic acid film to the mold is not particularly limited. For example, the film may be set along the inner surface of the mold (set inside the mold) or the mold may be a film. The film may be set along the outer surface of the mold and covered (set on the outside of the mold), or the film may be set between two molds.

  The imidization may be performed by heating to an imidization temperature or higher, or may be performed by chemical dehydration. In the case of imidization by heating, depending on the composition of the polyimide and the presence or absence of a catalyst, for example, the heating may be performed at 300 to 400 ° C. for 10 to 60 minutes.

  In the case of chemical dehydration, a dehydrating agent may be added to the polyamic acid solution at the time of preparing the polyamic acid film. Examples of the dehydrating agent include organic carboxylic acid anhydrides, N, N′-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, thionyl halides, and the like. Of these, organic carboxylic acid anhydrides are preferred. Examples of organic carboxylic acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, and their intermolecular anhydrides. In addition, anhydrides of aromatic monocarboxylic acids, for example, anhydrides such as benzoic acid and naphthoic acid, and anhydrides of carbonic acid, formic acid and aliphatic ketenes (ketene and dimethylketene) can be mentioned. These can be used alone or as a mixture of two or more, and among them, acetic anhydride is preferable.

  The amount of the dehydrating agent is preferably 0.5 to 4 mol, particularly preferably 1 to 3 mol, per 1 mol of the polyamic acid amide acid unit constituting the film. When the amount of the dehydrating agent is less than 0.5 mol with respect to 1 mol of the amic acid unit, the imidization reaction does not proceed sufficiently, and the mechanical properties of the resulting polyimide may be greatly reduced. On the other hand, when the amount of the dehydrating agent is more than 4 mol, it is necessary to raise the temperature in order to evaporate excess dehydrating agent, so that the mechanical properties of the resulting polyimide film may be greatly reduced.

  A tertiary amine may be added to promote imidization. Examples of the tertiary amine include trimethylamine, triethylamine, triethylenediamine, pyridine, picoline, quinoline, isoquinoline, lutidine, and the like. , Β-picoline, γ-picoline, quinoline and isoquinoline. The amount of the tertiary amine is 0.1 to 2 mol, more preferably 0.2 to 1 mol, relative to 1 mol of the amic acid unit of the polyamic acid constituting the film. When the amount of the tertiary amine is less than 0.1 mol relative to 1 mol of the amic acid unit, the mechanical properties of the resulting polyimide may be greatly reduced. If the amount exceeds 2 mol, tertiary amine may remain in the film, and it is necessary to raise the temperature in order to evaporate excess tertiary amine.

  A filler may be added to the polyamic acid film according to the function required for the polyimide resin molded body. Generally, the addition amount of a filler is 1-50 mass%. When the addition amount is less than 1% by mass, the function of the filler is hardly exhibited, and when it exceeds 50% by mass, not only the mechanical strength is lowered, but also appearance unevenness may occur. Regarding the type of filler, for example, to increase the dielectric constant of the film, carbon, barium titanate, etc., to increase the thermal conductivity, boron nitride, carbon fiber, etc., to increase the slidability. In this case, it is preferable to add a fluororesin such as polytetrafluoroethylene (PTFE) or a modified product thereof, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

  As described above, a polyimide resin molded body can be obtained by setting the polyamic acid film in a mold and imidizing it. Since a single film is used, an unnecessary portion may be generated as a molded body. However, the unnecessary portion may be removed by cutting or the like as appropriate. In the production method of the present invention, since a uniform film having a small thickness can be used for molding, a molded article of polyimide resin having high dimensional stability and a small thickness can be easily obtained. From the viewpoint of sufficiently exerting the effect of the present invention, the thickness of the polyimide resin molded body is preferably 10 to 500 μm.

  Another aspect of the present invention is a polyamic acid film for producing a polyimide resin molded body having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60%, and the polyamic acid film is applied to the above production method. It is the same as the film to be used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples.

First, the evaluation method employed in this example will be described.
Tensile modulus and elongation Measured according to JIS K6251 (2004). Tensilon UTM1000 (manufactured by Orientec) was used as the tensile tester, the sample was dumbbell-shaped No. 3, the distance between chucks was 30 mm, and the tensile speed was 100 mm / min.

The thickness of the polyimide resin molded body was measured using a 1/1000 mm dial gauge. In the case where the molded body was a plate shape, a total of 9 points were measured: one point at the center of the bottom surface, four points near the outer periphery of the bottom surface (approximately every π / 2), and four points on the side surface (every π / 2). In the case of the corrugated shape, a total of 5 points were measured: 1 peak, 1 valley, and 3 midpoints between peaks and valleys. The thickness was evaluated from the coefficient of variation (%) = (standard deviation / average) × 100.

Example 1
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and substantially equivalent p-phenylenediamine were dissolved in N-methyl-2-pyrrolidone (NMP) (monomer concentration 20% by mass). ). This solution was stirred at room temperature, stirred while heating to 70 ° C., and amidated to prepare a polyamic acid solution having a viscosity of 200 Pa · s measured by a B-type viscometer at 23 ° C.

  Next, this polyamic acid solution was applied to a glass plate so as to have a thickness of 0.5 mm, and then dried by heating at 130 ° C. for 30 minutes to prepare a polyamic acid film. The residual NMP content of this polyamic acid film was 15% by mass, the tensile modulus was 1280 MPa, and the elongation was 48%.

  This film was placed on a cylindrical (Φ70 mm) mold and set so that the film was on the cylindrical side of the mold. This was heated at 350 ° C. for 20 minutes for imidization to obtain a dish-shaped molded body having a bottom surface and side surfaces. When the film thickness was measured, the coefficient of variation was 3%.

Example 2
The polyamic acid film obtained in Example 1 was sandwiched between mesh-type corrugated molds. This was heated at 350 ° C. for 20 minutes for imidization to obtain a corrugated film molded body. When the film thickness was measured, the coefficient of variation was 1%.

Comparative Example 1
The polyamic acid solution obtained in Example 1 was applied to a glass plate to a thickness of 0.5 mm, and then dried by heating at 130 ° C. for 20 minutes to produce a polyamic acid film. The polyamic acid film was wrinkled on the surface after cooling. The residual NMP content of this polyamic acid film was 20% by mass, the tensile modulus was 660 MPa, and the elongation was 35%.

  This film was placed on a cylindrical (Φ70 mm) mold and set so that the film was on the cylindrical side of the mold. This was imidized by heating at 350 ° C. for 20 minutes to obtain a dish-shaped molded body having a bottom surface and a side surface, but the shrinkage unevenness was large, and when the film thickness was measured, the coefficient of variation was 8%. It was.

Comparative Example 2
The polyamic acid solution obtained in Example 1 was applied to a glass plate to a thickness of 0.5 mm, and then dried by heating at 200 ° C. for 20 minutes to produce a polyamic acid film. The residual NMP content of this polyamic acid film was 4% by mass, the tensile modulus was 2170 MPa, and the elongation was 60%.

  This film was placed on a cylindrical (Φ70 mm) mold and set so that the film was on the cylindrical side of the mold. When this was imidized by heating at 350 ° C. for 20 minutes, the flexibility of the film was insufficient, so that it did not follow the mold, and a large wrinkle occurred on the cylindrical side surface of the mold, A dish-shaped molded article having a clean side surface could not be obtained.

Comparative Example 3
A bottomed cylindrical container (Φ70 mm) was placed upside down (with the bottom face up). The polyamic acid solution obtained in Example 1 was placed on the bottom surface (upper surface) of the cylindrical container, and the container was tilted to allow the polyamic acid solution to reach the upper part of the side surface of the container. The direction in which the container is tilted was changed by 360 ° so that the polyamic acid solution was applied to the upper surface of the cylindrical container and the upper part of the side surface. This was dried at 130 ° C. for 30 minutes and then heated at 350 ° C. for 20 minutes for imidization. When the film thickness of the obtained molded body was measured, the coefficient of variation was 45%.

  According to the present invention, a molded article of polyimide resin having high dimensional stability and a small thickness can be obtained in various shapes, and the molded article is suitable for various fields where thin polyimide resin molded articles are used. Can be used.

Claims (4)

  A method for producing a polyimide resin molded body, wherein a polyamic acid film having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60% is set in a mold and imidized.   The manufacturing method according to claim 1, wherein the polyamic acid film is obtained by applying a solution of polyamic acid on a support and drying it until the amount of residual solvent is 5 to 18% by mass.   The manufacturing method according to claim 1 or 2, wherein the polyimide resin molded body has a thickness of 10 to 500 µm.   A polyamic acid film for producing a polyimide resin molded body having a tensile elastic modulus of 900 to 1500 MPa and an elongation of 30 to 60%.