JPH0653796B2 - Copolyimide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a copolyimide having a novel structure having extremely high heat resistance, elastic modulus and strength.

[Object of the Invention]

That is, the present invention has the general formula The repeating unit (A): repeating unit (B) is present in a molar ratio of 20:80 to 80:20 and has a concentration of 0.5 g / dl in 97% concentrated sulfuric acid and a temperature of 30 ° C. Logarithmic fold (ηinh) measured at temperature is 0.5dl / g-10dl /
g relates to copolyimide.

[Structure of Invention]

 Hereinafter, the present invention will be described in detail.

The copolyimide of the present invention comprises biphenyl tetracarboxylic acid dianhydride (hereinafter referred to as component (a)), 3,3′-dimethylbenzidine (hereinafter referred to as component (b)) and 4,4′-diaminodiphenyl ether. (Hereinafter referred to as (c) component) and (b) component
The total amount of the component (c) is substantially equimolar to the amount of the component (a), and the component (b) and the component (c) are charged in a molar ratio of 20:80 to 80:20. The copolyimide precursor (copolyamic acid) is produced by reacting it in a solvent at a low temperature, and then produced by imidization by a conventional method. Alternatively, the copolyimide can be produced in a single step by reacting in an organic solvent at a high temperature.

The reaction between the component (a), the component (b) and the component (c) is an organic solvent,
For example, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylpyrropionamide, N-methyl-2-pyrrolidone, 1,5-dimethyl-2
-Pyrrolidones such as pyrrolidone, phenols such as phenol, p-chlorophenol, o-chlorophenol and the like, dimethylsulfoxide, etc. alone or in a mixed solvent or in a mixed solvent with a small amount of another organic solvent. Be implemented.

The first stage reaction to produce copolyamic acid is relatively low temperature,
For example, it is preferable to carry out at a temperature of 50 ° C. or lower, and generally, a solution prepared by dissolving the components (b) and (c) in a suitable organic solvent is kept under cooling, and the component (a) is added to this solution. The reaction can be carried out.

The copolyamic acid solution thus obtained can be imidized by various methods.

For example, (a) a method of heating and dehydrating as it is to imidize (b) a method of casting a copolyamic acid solution on a glass plate and the like, and then heating and dehydrating to imidize (c) a third copolyamic acid solution. A method of adding and mixing an imidization catalyst such as a primary amine and an acid anhydride and then casting on a glass plate or the like, and performing dehydration at room temperature or by heating and dehydration to imidize (d) Putting in a large amount of a poor solvent such as acetone. Precipitation, separated powders are heated and dried to imidize (e) Imidization catalysts such as tertiary amine and acid anhydride in an imidization catalyst or in an organic solvent containing them at room temperature or by heat dehydration to imidize There is.

The copolyimide of the present invention has a high molecular weight necessary for forming a film or a molded product, that is, 0.5% in 97% concentrated sulfuric acid.
Logarithmic viscosity ηinh measured at a concentration of g / dl and a temperature of 30 ° C
Is 0.5 to 10 dl / g, preferably 1 dl / g or more and 5 dl / g or less. Here, the logarithmic viscosity ηinh is the following formula: ηinh = ln (ηrel) / C (where C is the concentration of the polymer solution (polymer g / solvent 100)
ml) and ηrel is a relative viscosity, that is, a measured value defined by the ratio of the flow times of the polymer solution and the solvent measured by a capillary viscometer. ).

In the copolyimide of the present invention, the repeating units shown in (A) and (B) above are 20:80 to 80:20, preferably 30:70 to 70:30 (molar ratio). As will be apparent from Examples and Reference Examples described later, of course, in each individual system, if the ratio of (A) and (B) is outside the above range, the high elastic modulus of the object of the present invention, a high-strength copolyimide is obtained. Because you cannot get it. That is, when the ratio of (A) is less than the above range, the elastic modulus and heat resistance (Tg) are not sufficiently improved, and when the ratio of (A) is more than the above range, the elastic modulus is high but the strength and elongation are high. Only very low values of can be obtained.

The copolyimide of the present invention can be obtained as a film by the above-mentioned imidization method. Alternatively, it can be obtained as a powder once and then formed into a molded body by a known method. Further, since the copolyimide of the present invention is easily dissolved in concentrated sulfuric acid or fuming sulfuric acid, it can be made into a fiber or the like.

The copolyimide of the present invention may be blended with a well-known compounding agent such as an antioxidant, a heat stabilizer, a UV absorber, a colorant, a filler and the like in accordance with a formulation known per se.

[Examples] The present invention will be described in detail with reference to Examples below, but the present invention is not limited to the following Examples without departing from the gist thereof.

The film characteristics were evaluated as follows.

Tensile test: 20 according to the test method of ASTM B638
It was measured at ° C.

Glass transition temperature (hereinafter abbreviated as Tg): Measured at a temperature rising rate of 10 ° C./min using a thermal mechanical analyzer manufactured by Shimadzu Corporation.

Also, the logarithmic viscosity (ηin
h) was measured in 97% concentrated sulfuric acid at a concentration of 0.5 g / dl and a temperature of 30 ° C.

Example 1 4,4'-diaminodiphenyl ether (hereinafter abbreviated as ODA) 3.0 in a 500 ml four-necked flask equipped with a stirrer.
g, 3,3'-Dimethylbenzidine (hereinafter abbreviated as OTD)
9.6 g was precisely weighed, and 290 ml of N, N-dimethylacetamide (hereinafter abbreviated as DMAC) was added and dissolved. Then, 17.7 g of biphenyl tetracarboxylic dianhydride (hereinafter abbreviated as BPDA) was added and the reaction was carried out at room temperature for 6 hours.
The viscosity of the solution increases with the progress of the reaction, and 10% by weight of OT
An amic acid copolymer solution with D / ODA = 75/25 (molar ratio) was obtained. A part of this copolyamic acid solution is used as N-methyl-2-
0.5g / diluted with pyrrolidone (hereinafter abbreviated as NMP)
A dl solution was prepared and the logarithmic viscosity (hereinafter referred to as ηinh) was measured and found to be 2.7 dl / g. From the infrared absorption spectrum, absorption of amide (N—H) was observed at 3280 cm ⁻¹ .

This copolyamic acid solution was formed into a thin film on a glass plate with a doctor knife and dried at 70 ° C. for 90 minutes in a hot air drying oven.

Then, this semi-dried film was fixed on a metal frame, heat-treated at a temperature of 70 ° C. to 300 ° C., and finally heat-treated at 300 ° C. for 15 minutes to obtain a copolyimide film having a thickness of 35 μm.

Taking the infrared absorption spectrum of this film, new strong imide absorption was observed at 1780 cm ^-1 and 730 cm ^-1.
Absorption of NH at 3280 cm ^-1 was completely gone.

The tensile properties of this film were an elastic modulus of 550 kg / mm ² , a strength of 25 kg / mm ² , and a breaking elongation of 25%.

The Tg of this copolyimide is 400 ° C or higher,
h was 1.6 dl / g.

Example 2 The procedure of Example 1 was repeated except that 6.0 g of ODA, 6.4 g of OTD and 17.7 g of BPDA were used, and the logarithmic viscosity was 2.6 gl / g.
An amic acid copolymer solution with BPDA / ODA = 50/50 (molar ratio) was prepared.

A copolyimide film having a thickness of 38 μm was obtained from this copolyamic acid solution in the same manner as in Example 1. The tensile properties of this film are as follows: elastic modulus 500 kg / mm ² , strength 23 kg / m
It was m ² and the breaking elongation was 45%. The copolyimide had a Tg of about 370 ° C. and an ηinh of 2.1 dl / g.

The elemental analysis values of the above copolyimide are C: 74.6%, H:
It was 3.5%, O: 15.7%, N: 6.0%.
The theoretical value [repeating unit (A) / repeating unit (B) = 50/50
(Molar ratio)] is C: 75.0%, H: 3.5%, O:
15.5% and N: 6.0%. The infrared absorption spectrum of the 8 μm thick copolyimide film prepared in the same manner is shown in FIG.

Example 3 To the copolyamic acid solution prepared in Example 2, 1 mol of isoquinoline and 4 mol of acetic anhydride were added to 1 mol of BPDA unit of copolyamic acid, and after mixing well, they were placed on a glass plate with a doctor knife. A coating film was formed and dried in a hot air drying oven at 120 ° C for 10 minutes. Then, this semi-dried film was fixed on a metal frame, heat-treated at 200 ° C. for 12 minutes, and further heat-treated at 300 ° C. for 15 minutes to obtain a 40 μm-thick copolyimide film.

The tensile properties of this film were an elastic modulus of 560 kg / mm ² , a strength of 28 kg / mm ² , and a breaking elongation of 50%. The ηinh of this copolyimide was 2.1 dl / g. The Tg was 400 ° C or higher.

Example 4 From the copolyamic acid solution prepared in Example 2, a thin film was formed on a glass plate with a doctor knife and dried in a hot air drying oven at 70 ° C. for 90 minutes to obtain a semi-dried film. Acetic anhydride, pyridine, toluene,
After immersing in a mixed solution of 200 ml, 300 ml, and 500 ml for 20 hours, it was fixed on a metal frame and heat-treated in the same manner as in Example 3 to obtain a copolyimide film having a thickness of 37 μm.

The tensile properties of this film were an elastic modulus of 570 kg / mm ² , a strength of 30 kg / mm ² , and a breaking elongation of 51%. The ηinh of this copolyimide was 2.0 dl / g.

The Tg was 400 ° C or higher.

Example 5 ηinh obtained by the same operation as in Example 1 except that 9.0 g of ODA, 3.2 g of OTD, and 7.7 g of BPDA were used.
A copolyimide film having a thickness of 37 μm was produced by the procedure of Example 1 from an amic acid copolymer solution having 2.4 dl / g and OTD / ODA = 25/75 (molar ratio).

The tensile properties of this film are 400 kg / mm ^{2 in} elastic modulus and ² in strength.
It was 3 kg / mm ² and the elongation at break was 60%. The ηinh of this copolyimide was 1.6 dl / g. The Tg was 340 ° C.

Comparative Example 1 Except that 12.0 g of ODA and 17.7 g of BPDA were used,
By the same operation as in Example 1, a polyamic acid solution having an intrinsic viscosity of 2.3 dlg was obtained.

38 μm thick produced from this solution by the procedure of Example 1.
Tensile properties of the polyimide film are elastic modulus 300kg / m
It had a m ² , a strength of 15 kg / mm ² , and a breaking elongation of 60%. Ηinh of this polyimide was 1.2 dl / g. Tg is 280 ℃
It was.

Comparative Example 2 Except that 12.7 g of OTD and 17.7 g of BPDA were used,
By the same procedure as in Example 1, a polyamic acid solution having an intrinsic viscosity of 2.8 dl / g was obtained.

The 38 μm polyimide film produced from this solution by the procedure of Example 1 had tensile properties of a strength of 14 kg / mm ² , a breaking elongation of 4% and an elastic modulus of 580. Ηinh of this polyimide was 1.2 dl / g. The Tg was 400 ° C or higher.

Comparative Example 3 ηin obtained by the same operation as in Example 1 except that 10.8 g of ODA, 1.3 g of OTD, and 17.7 g of BPDA were used.
A 37 μm thick copolyimide film was produced from an amic acid copolymer solution with h = 2.5 dl / g and OTD / ODA = 1/9 (molar ratio).

The tensile elasticity of this film was an elastic modulus of 320 kg / mm ² , a strength of 16 kg / mm ² , and a breaking elongation of 55%. The ηinh of this copolyimide was 1.0 dl / g. The Tg was 315 ° C.

Comparative Example 4 ηin obtained by the same operation as in Example 1 except that 1.2 g of ODA, 11.5 g of OTD, and 17.7 g of BPDA were used.
A 37 µm thick copolyimide film was produced from an amic acid copolymer solution having h = 2.6 dl / g and OTD / ODA = 9/1 (molar ratio).

The tensile properties of this film were an elastic modulus of 540 kg / mm ² , a strength of 17.0 kg / mm ² , and a breaking elongation of 5%. The ηinh of this copolyimide was 1.2 dl / g. The Tg was 400 ° C or higher.

〔The invention's effect〕

As described above, according to the present invention, a copolyimide having a novel structure having extremely high heat resistance, elastic modulus, strength and elongation can be obtained.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum diagram of the copolyimide of the present invention obtained in Example 2.

Claims (1)

[Claims] 1. A general formula The repeating unit (A): repeating unit (B) is present in a molar ratio of 20:80 to 80:20 and has a concentration of 0.5 g / dl in 97% concentrated sulfuric acid and a temperature of 30 ° C. Logarithmic viscosity (ηinh) measured at temperature is 0.5dl / g-10dl /
Copolyimide characterized by being g.