JPS634572B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyimide molded article, particularly a film, which has excellent strength and heat resistance. That is, the present invention is directed to the molar ratio (DADE:DABA) of 4,4'-diaminodiphenyl ether (hereinafter sometimes abbreviated as DADE) and diaminobenzoic acid (hereinafter sometimes abbreviated as DABA).
is 50:50 to 0:100,
A solution of polyamic acid (also called polyamic acid) obtained by polymerizing 3,3',4,4'-biphenyltetracarboxylic dianhydride in an organic polar solvent at a temperature of 0 to 80°C. The present invention relates to a method for producing a polyimide molded article, which comprises molding a polyamic acid molded article and then heating the polyamic acid molded article at a high temperature. Conventionally, known polyimides contain an aromatic diamine component and an aromatic tetracarboxylic dianhydride component,
Polyamic acid is polymerized in approximately equimolar amounts in an organic polar solvent at a temperature of approximately 80°C or lower, and while forming a film from the polyamic acid solution (reaction liquid), the imide ring is thermally or chemically formed. It is known that polyimide films can be produced by In particular, JP-A No. 55-7805 discloses aromatic fragrances in which the molar ratio (DADE/PPD) of 4,4'-diaminodiphenyl ether (DADE) and P-phenylenediamine (PPD) is 0 to 2.5. The group diamine component and 3,3',4,4'-biphenyltetracarboxylic dianhydride are mixed in an organic polar solvent at 0 to 80°C.
A method for producing a heat-resistant polyimide molded product with extremely high strength by molding a polyamic acid molded product from a polyamic acid solution obtained by polymerization at a temperature of , and then heating the polyamic acid molded product. It is written about. However, the dynamic viscoelasticity of the known polyimide molded article sharply decreases at temperatures of 300° C. or higher, and there were problems with heat resistance at such high temperatures. The inventors discovered that even at high temperatures of 300°C or higher,
As a result of various research into methods for manufacturing polyimide molded products that do not significantly reduce dynamic viscoelasticity and maintain heat resistance, we have developed an aromatic diamine component mainly containing diaminobenzoic acid (DABA) instead of PPD. , 3,3',4,4'-biphenyltetracarboxylic acid component in an organic polar solvent,
By molding a polyamic acid molded product from a polyamic acid solution obtained by polymerization at a temperature of 0 to 80°C and heating the molded product to a high temperature, a polyimide molded product with excellent heat resistance can be obtained. discovered that it could be done, and completed this invention. The polyimide molded product obtained by the method of this invention has extremely excellent heat resistance at high temperatures (300°C or higher). For example, the polyimide film obtained by the method of this invention has a temperature of approximately Ten
×10 ⁹ dyne/cm ² or more dynamic viscoelasticity, 300℃
It also has excellent heat resistance with dynamic viscoelasticity of about 15×10 ⁹ dyne/cm ² or more. The polyamic acid used in the method of this invention has a molar ratio of 4,4'-diaminodiphenyl ether (DADE) to diaminobenzoic acid (DABA) (DADE:DABA) of 50:50 to 0:100, particularly 40 :60 to 0:100,
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) is polymerized in approximately equimolar amounts in an organic polar solvent at a temperature of 0 to 80°C, particularly 5 to 60°C. It is a high molecular weight polyamic acid. The aromatic diamine component may be composed of DABA alone or a mixture of DABA and DADE, and in addition to the diamine component, other aromatic diamines such as m-, p-phenylene diamine, 4 , 4'-diaminodiphenyl thioether, 4,4'-diaminodiphenyl sulfone,
4,4'-diaminodiphenylmethane, etc., in an amount of about 15 mol% or less based on the total aromatic diamine component, especially
If it is 10 mol% or less, DABA alone or
It may also be used with a mixture of DABA and DADE. As the diaminobenzoic acid (DABA),
Mention may be made, for example, of 3,5-diaminobenzoic acid, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid or mixtures thereof, in particular 3,5-diaminobenzoic acid or 3,5-diaminobenzoic acid. Mixtures based on diaminobenzoic acid are preferred. The above-mentioned aromatic diamine component should contain 50 mol% or more of DABA, especially 60 mol% of the total aromatic diamine component, since the DABA content decreases and the heat resistance of the polyimide molded product at high temperatures decreases.
It is preferable that it is contained in the above ratio. The above-mentioned 3,3',4,4'-biphenyltetracarboxylic dianhydride may be substituted with other aromatic tetracarboxylic dianhydrides, such as 2,3,3',4'-biphenyltetracarboxylic acid. Dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic acid, bis(3,4-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl) ) An acid dianhydride such as ether may be contained in a proportion of 10 mol % or less, particularly 5 mol % or less, based on the total acid dianhydride. In the above-mentioned polymerization of both monomer components, all of the aromatic diamine components and all of the aromatic tetracarboxylic acid components are added to the solvent in approximately equal moles, particularly substantially equal moles, simultaneously or in stages. It is preferable to carry out the polymerization. That is, in the polymerization, the difference (moles) in the amounts used between the aromatic diamine component and the aromatic tetracarboxylic dianhydride component is 5 mol% with respect to the total number of moles of the aromatic tetracarboxylic dianhydride component. Hereinafter, it is preferable that both monomer components are added to the polymerization solvent and polymerized so that the amount is particularly 3 mol % or less, more preferably 2 mol % or less. In the method of this invention, polyamic acid is
Logarithmic viscosity (30℃, concentration 0.5g/100ml N-methyl
2-pyrrolidone) has a high molecular weight of 0.3 or more, particularly 0.5 to 7, more preferably about 0.7 to 5. If this logarithmic viscosity is too low, the strength and heat resistance of the polyimide molded product obtained This is not preferable because it reduces In order to produce polyamic acid having a logarithmic viscosity of 0.3 or more, the difference (in moles) in the amounts added to the polymerization solvent of the aromatic diamine component and the aromatic tetracarboxylic dianhydride is Both monomer components are added to the polymerization solvent in an amount of 1.5 mol% or less, particularly 1.0 mol% or less, more preferably 0.5 mol% or less, based on the total number of moles of the monomer components, and the polymerization temperature is adjusted to about 0 to 60°C, especially 5 mol% or less. It is optimal to carry out the polymerization at a temperature of ~50°C and a polymerization time of 0.5 to 20 hours, particularly 1 to 15 hours. In the method of this invention, the polyamic acid solution may be prepared by using the above-mentioned polymerization solution as it is, or by once isolating and purifying the polyamic acid and dissolving it in the same organic polar solvent as used in the polymerization. It may also be a solution containing The organic polar solvent used for polymerization in the method of this invention includes N-methyl-2-pyrrolidone,
Amide solvents such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylcaprolactam, sulfoxide solvents such as dimethylsulfoxide and diethylsulfoxide, tetra Suitable examples include solvents that can sufficiently dissolve polyamic acid, such as alkyl urea solvents such as methylurea and tetraethyl urea, and phenolic solvents such as cresol and phenol. In the method of the present invention, the method of forming a polyamic acid molded article while gradually removing the solvent from a polyamic acid solution may be carried out by any known method. When molding a polyamic acid film, a polyamic acid solution is mixed into glass plates, copper plates,
A thin film of the solution is formed by casting on a flat plate with a smooth surface such as an aluminum plate or a stainless steel plate, and the solvent is gradually removed from the thin film by heating. diameter rotating roll,
Alternatively, a method may be used in which a solution of polyamic acid is cast onto a metal belt to form a thin film of the solution on a rotating drum or belt, and the solvent is gradually removed from the thin film. The polyamic acid molded product formed as described above is heated to a temperature of 100 to 350°C to convert the amide-acid bond of the polyamic acid to an imide bond, thereby obtaining a polyimide molded product. Note that the removal of the solvent during molding of a molded product (film) from a thin film of a solution of polyamic acid and the heating for imide cyclization of the polyamic acid molded product may be performed continuously, or the removal of the solvent may be performed continuously. The second half and the first half of imide cyclization may be performed simultaneously in an overlapping manner. In the latter half of the heating of the polyamic acid molded article described above, or after imidization by heating is completed, the molded article is heated to a high temperature of 250 to 500°C, particularly 300 to 450°C. The polyimide molded product obtained by the method of the present invention has no dislocation point (Tg) and has excellent heat resistance without a sudden drop in dynamic viscoelasticity at high temperatures of 300° C. or higher. Examples and comparative examples of the present invention will be shown below. Example 1 Into a 14 cylindrical polymerization tank, 1.80 mol of 3,5-diaminobenzoic acid as an aromatic diamine component and 3,3', 3,3',
4,4'-biphenyltetracarboxylic dianhydride
1.80 mol, and N-methyl-2-pyrrolidone 6
was added and stirred at room temperature (30°C) for 6 hours to obtain a solution of polyamic acid having a logarithmic viscosity (30°C, 0.5g/100ml N-methyl-2-pyrrolidone) of 1.7. The polyamic acid solution was placed on a glass plate at 25°C.
to form a thin film of polyamic acid solution,
The thin film was kept under reduced pressure (approximately 1 mmHg) at room temperature for 1 hour.
The solution was then maintained at 120° C. and vacuum for 1.5 hours to evaporate the solvent to form a polyamic acid film (approximately 30μ). The polyamic acid film was peeled off from the glass plate, attached to a metal frame, and heated from room temperature to 200°C in about 30 minutes, then from 200°C to 300°C in about 30 minutes, and then heated to 300°C for about 1 hour. The polyamic acid film was then imide-cyclized to form a polyimide film. The polyimide film was subjected to a tensile strength test and a dynamic viscoelasticity test, and the results are shown in Table 1. Example 2 Polyamic acid was polymerized in the same manner as in Example 1, except that 1.44 mmol of 3,5-diaminobenzoic acid and 0.36 mmol of 4,4'-diaminophenyl ether were used as the aromatic diamine component. A solution was prepared. In addition to using the polyamic acid solution,
A polyimide film was formed in the same manner as in Example 1. The test results for the film are shown in Table 1. Example 3 Polyamic acid was obtained by polymerizing in the same manner as in Example 1, except that 0.9 mol of 3,5-diaminobenzoic acid and 0.9 mol of 4,4'-diaminophenyl ether were used as aromatic diamine components. A solution was prepared. A polyimide film was formed in the same manner as in Example 1 except that the polyamic acid solution was used. The test results for the film are shown in Table 1. Comparative Example 1 The same procedure as Example 1 was carried out except that P-phenylenediamine was used as the aromatic diamine component, a solution of polyamic acid was produced by polymerization in the same manner as in Example 1, and that solution was used. A film was formed in the same way,
A polyimide film was formed. The test results for the film are shown in Table 1. 【table】

Claims (1)

[Claims] 1 4,4'-diaminodiphenyl ether (hereinafter
(abbreviated as DADE) and diaminobenzoic acid (hereinafter referred to as
(abbreviated as DABA) and molar ratio (DADE:
DABA) of 50:50 to 0:100 and 3,3',4,4'-biphenyltetracarboxylic dianhydride in an organic polar solvent of 0 to 80%
1. A method for producing a polyimide molded article, which comprises molding a polyamic acid molded article from a solution of polyamic acid obtained by polymerization at a temperature of 10.degree. C., and then heating the polyamic acid molded article at a high temperature.