JPS63230320A - Stretched film manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a film excellent in its strength, modulus and dimension stability by a method in which carboxylic acid monoanhydride and imidation catalyst of a specified amount are mixed with the organic soluvent solution of aromatic polyamic acid, and the mixture is cast on a substrate, and then the film obtained by heating is orientated. CONSTITUTION:0.7mol or more carboxylic acid monoanhydride and a little amount of imidation catalyst are added in an organic solvent solution of polyamic acid of polyimide precussor composed of aromatic tetracarboxylic acid dianhydride and aromatic diamine, and are agitated and mixed. Then, the mixture is cast on a substrate and is molded into a thin film. Next, said thin film is heated in a hot blast drying furnace, and after it has been imidated by drying until the residual solvent amount reaches 10-80wt.%, it is separated from the substrate to give a self supporting semidried film. the obtained film is uniaxially or biaxially orientated at the ratio of 1.1 times or more in an aqueous medium, and is heated and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a stretched film of aromatic polyimide. Due to its excellent heat resistance, mechanical, electrical properties, and chemical resistance, polyimide has long been used in space equipment and heavy electrical equipment, and more recently in the electronics field such as LSI insulation films and flexible printed circuit boards. It is used.

[Conventional technology]

A polyimide film is generally produced by casting a polyimide precursor solution onto a support, heating and drying it to obtain a self-supporting half-dried film, and further heating it, and is a non-stretched film.

As a method for producing a stretched polyimide film, the method is as follows: Journal of the Chemical Society of Japan (2) JRIF (/7ff) is cast with polyamic acid, dried to obtain a half-dried film, stretched in an aqueous medium, and then thermally ring-closed. A method for obtaining a stretched polyimide film has been proposed, but no mention is made of its contribution to physical properties.

Tokukai Akira again! In Patent No. 73/2011, 0.00% of the amic acid unit is added to the polyamic acid solution. / -0,3! A method is described in which the fiber is spun into a partially imidized coagulated liquid by adding an equivalent amount of a chemical ring-closing agent, and after stretching, the process is further imidized by adding a chemical ring-closing agent, but the process is complicated.

[Problem that the invention seeks to solve]

Therefore, the present inventors have intensively studied an improved method for producing stretched polyimide films, and as a result, have arrived at the present invention.

[Means for solving problems]

That is, the gist of the present invention is to mix an organic solvent solution of aromatic polyamic acid with 0.7 mol or more of carboxylic acid anhydride and a small amount of imidization solvent per amic acid unit, and then cast the mixture onto a support. By heating, a self-supporting film is obtained which is diimidized and has a residual solvent amount of 10 to 10% by weight. The method for producing a polyimide film is characterized in that the self-supporting film thus obtained is stretched in one or two directions in an aqueous medium to a ratio of 1 times the width and then heated and dried.

The polyimide film obtained by the method of the present invention is characterized by repeating units represented by the following structural formula.

(However, in the formula, R is a V-valent group having at least 7 aromatic rings.

R' is a divalent group having at least one aromatic ring. ) The polyamic acid of the polyimide precursor used in the production of the polyimide film in the present invention has the following general formula (i
i) (However, R and R' in the formula have the same meanings as in the above general formula (1))
A polymer having a large number of repeating positions represented by
0.0 in N,N-dimethylformamide. j f/dl and the intrinsic viscosity (ηinh) measured at 30°C is at least 0 Jdl/? It is preferable that This is because if the intrinsic viscosity is smaller than o, zct17f, only a film with inferior strength can be obtained.

Here, the intrinsic viscosity (ηinh) is expressed by the following formula (% formula %) (where C is the concentration of the polymer solution (polymer 2/solvent 100
m1), and ηrθl is a measured value defined as the relative viscosity, ie the ratio of the flow times of the polymer solution and the solvent measured with a capillary viscometer.

The polyamic acid can be prepared by a known method, for example, Japanese Patent Publication No. 3A-1.
It is manufactured by the method described in 0 Tatata Publication, 3g-r Publication, 2so Publication, etc. That is, at least one organic diamine represented by the structural formula % (wherein R' is a covalent group having at least one aromatic ring) and the structural formula (wherein R' is a covalent group having at least one aromatic ring) R is a V-valent organic group having at least 7 aromatic rings) At least one tetracarboxylic dianhydride represented by R is reacted in an organic polar solvent under substantially anhydrous conditions. It is produced by carrying out the reaction while maintaining the temperature inside to below 10°C, preferably below 10°C.

Tetracarboxylic dianhydrides suitable for use in the present invention include pyromellitic dianhydride, 3.3', ≠, ≠'-
diphenyltetracarboxylic dianhydride, 3.3', ≠,
v'-benzophenone tetracarboxylic dianhydride, 2,
3. t, 7-naphthalene tetracarboxylic dianhydride,
2. J-bis(3,II-dicarboxyphenyl)propanihydride, bis(3,a-dicarboxyphenyl)
These include ether dianhydride, ethylenetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, and the like.

Diamines suitable for use in the present invention include m-phenylenediamine, p-phenylenediamine tl, %I
- Diaminodiphenylpropane, l.

V'-diaminodiphenylmethane, ≠, ≠'-diaminodiphenyl ether, 0-)lysine, O-dianisidine, /,! Examples include -diaminonaphthalene F, ≠'-diaminodiphenylsulfide, and ≠'-diaminodiphenylsulfone.

Solvents useful in synthesizing the polyamic acids of this invention are water-soluble organic polar solvents whose functional groups do not react with the diamine or dianhydride. The organic polar solvent must be inert to the reaction system, be a solvent for the product, and must also be a solvent for at least the reactants. Preferred solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-corbyroliton, tetramethylenesulfone, dimethylsulfone, and the like. Solvents can be used alone or in combination.

The obtained polyamic acid is used in the production of polyimide films such as these. Conversion of polyamic acid to polyimide is carried out by a chemical method, and imidization is carried out using a combination of a dehydrating agent and an imidization catalyst.

A carboxylic acid anhydride is used as a dehydrating agent. Carboxylic acid anhydrides include acetic acid, propionic acid, isobutyric acid,
Included are aliphatic and aromatic carboxylic acid anhydrides such as benzoic acid, propylbenzoic acid, toluic acid, and the like. The amount of carboxylic acid-anhydride used is 0.7 mol or more based on the amic acid unit of the polyamic acid. If the amount used is less than 0.7 mol, a film with poor physical properties cannot be obtained.

-mer - In addition, as an imidization catalyst, pyridine, isoquinoline, 3
．． Examples include tertiary gauze amines such as j-lutidine, ≠-methylpyridine, and 3-methylpyridine, or imidazole and derivatives thereof, such as comethylimidazole and cophenylimidazole. The amount of imidization catalyst used is 0.00/amic acid unit of polyamic acid.
Above, preferably 0.0/~1 mol.

The concentration of polyamic acid in the organic solvent is 1-10% by weight, preferably 7-20% by weight. Note that the polyamic acid solution is prepared according to a conventional method. For example, it can be produced by mixing a tetracarboxylic dianhydride with a diamine solvent solution and stirring the mixture at around room temperature. The temperature for chemical imidization is 10°C or higher and 2JtO°C or lower, preferably 10
The temperature is 0°C or more and θO°C or less. At temperatures lower than ♂O°C, imidization proceeds, but the solvent oozes out, making it impossible to obtain a molded product with a clean surface. Moreover, at temperatures above λjO°C, the surface properties of the molded product deteriorate due to rapid imidization.

81 In the present invention, the stretched polyimide film is as follows (
It is manufactured through the steps 1) to 4V).

(1) Add 0.7 mol or more of carboxylic acid anhydride and a small amount of imide to the amic acid unit in an organic solvent solution of polyamic acid, which is a polyimide precursor consisting of aromatic tetracarboxylic dianhydride and aromatic diamine. After adding a catalyst and stirring and mixing, the mixed solution is cast onto a support such as a glass plate or an endless belt to form a thin film.

(ii) By heating the thin film in a hot air drying oven as described above, it is dried until the amount of residual solvent becomes 10 to 10% by weight, and after chemical ring closure (imidization), it is peeled off from the support and self-contained. A supportive, wet film is obtained.

OID The obtained film is stretched by 1.1 times or more in one or two directions in an aqueous medium using a stretching machine.

(X/) The stretched film is fixed to a fixed frame and dried by heating at a temperature of 0°C or higher, preferably 300°C to SOO°C.

Here, the aqueous medium is a liquid whose main component is water, and examples include water alone, a mixture of water and a solvent for the polyimide precursor solution, a mixture of water and lower alcohol, and a mixture of water and acetone. .

The solvent content of the film in the present invention was determined by the following formula.

〔Example〕

The present invention will be explained below with reference to Examples, but the present invention is not limited to the Examples unless the gist of the invention is omitted.

Reference Example 1 ψll'-diaminodiphenyl ether (hereinafter abbreviated as ODA), o-) lysine (hereinafter abbreviated as OTD), O, Tatata 7, and N, N-dimethylformamide (hereinafter abbreviated as OTD) were added to a polymerization pot of jOt. Abbreviated as DMF) Rich. 3
The broth was charged and stirred for 7 hours to completely dissolve the diamine component. Next, 2.03 kg of pyrometic acid dianhydride (hereinafter abbreviated as PMDA) was added little by little, and the reaction temperature was maintained at 20°C and polymerized for 10 hours with stirring to form a viscous polyimide precursor (polyamic acid). A solution was obtained. Take a part of this solution and dilute it with DMF to adjust the 0.1 t/di solution to obtain the logarithmic viscosity (ηtnh).
A polyimide film was produced in exactly the same manner as in Reference Example except that A was used alone.

The ηinh of the polyamic acid was λ, 2dllt.

Example 1 Polyamic acid solution obtained in Reference Example 1 //≠, Ri? acetic anhydride/2.1? (1, lr per amic acid unit
A solution consisting of 0.27f of isoquinoline Q and 100f of dimethylformamide (DMF) was added and mixed well under reduced pressure to form a homogeneous solution. Next, this bath liquid was cast onto a glass plate using a doctor knife to form a liquid film to obtain a dry film with a thickness of 1.2 μm, and heated at 100°C.
It was dried in a hot air drying oven for io minutes. The solvent content of the half-dried film peeled off from the glass plate was t/, 0 weight ratio. Infrared absorption spectrum is 17♂061n
Strong imide absorption was newly observed for 730 (M) and 730 (M), while absorption of N-H at 3210σ based on amic acid had completely disappeared. This semi-dry film was fixed in a manual stretching machine and stretched. f!: 10 wt% DM at uO°C
After immersing in the F aqueous solution for io minutes, it was stretched in one direction at a stretching speed of 10 mm for 1 minute, and then heated in a hot air drying oven at 720°C.
The temperature was increased from 230℃ in 11 minutes, and finally 3J
Heat treatment was performed for O'Q≠ minutes to obtain a uniaxially stretched film of about 2 j μm. The tensile properties of this film are shown in Table 1. Table 1 also shows the tensile properties of the film that was dried under irj drying conditions without being stretched.

=12- Table 1 Polyamic acid solution obtained in Example/Reference Example/J-F, At and acetic anhydride/3.3? (1 per amic acid unit, ≠
A solution consisting of isoquinoline 3 and DMFI A, 7 F was added and mixed well under reduced pressure to obtain a homogeneous solution, which was then formed into a film and stretched in the same manner as in Example 1.

Table 2 [Effects of the Invention] According to the method of the present invention, stretching can be achieved extremely effectively with a simple stretching process, and the resulting polyimide stretched film has high strength and high modulus, and is highly oriented. , Humidity expansion coefficient/Humidity [W] Small expansion coefficient, excellent dimensional stability.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - (7 others)

Claims (1)

[Claims] (1) (i) Add 0.7 mol or more of carboxylic acid-anhydride and a small amount of imidization catalyst per amic acid unit to an organic solvent solution of polyamic acid consisting of aromatic tetracarboxylic dianhydride and aromatic diamine. (ii) imidizing by heating to form a self-supporting film with a residual solvent amount of 10 to 80% by weight; (iii) the film. A method for producing a polyimide stretched film, comprising the steps of stretching the polyimide stretched film by 1.1 times or more in one or two directions in an aqueous medium, and (iv) heating and drying the stretched film.