JPH0613594B2 - Method for producing polyamide and / or polyimide - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improved process for producing polyamides and / or polyimides from polycarboxylic acids and diisocyanates.

[Prior art]

It is already known to produce a polyamide from a dicarboxylic acid and a diisocyanate, similarly producing a polyamic acid from a tricarboxylic acid or a tetracarboxylic acid and a diisocyanate, and further by using this polyamic acid as a precursor, an imide by intramolecular dehydration ring closure reaction. It is also known to form bonds to produce polyamide-imides or polyimides. Then, the production of the polyamide, the polyamic acid or the polyamic acid containing an imide bond in a part of the molecular chain by the reaction is generally a polyvalent carboxylic acid and a polyisocyanate in an organic polar solvent, at room temperature to 250 ° C. At a temperature of 1 to 20 hours. However, usually, this reaction product, compared to a polyamide produced from a diamine and a dibasic acid dihalide, or a polyamic acid produced from a diamine and a tricarboxylic acid anhydride halide or a tetracarboxylic acid dianhydride, Since a polymer having a low molecular weight and often a branched or crosslinked polymer is easily formed, problems such as increase in melt viscosity of the polymer and decrease in solubility occur, and thus a high molecular weight linear polymer which can be subjected to melt processing or solution processing is selected. It was difficult to get.

The present inventors, as an epoch-making method for producing a high-molecular weight polyamide from a polyvalent carboxylic acid and a diisocyanate, a method using an alkali metal salt of a polyvalent carboxylic acid disclosed in JP-A-57-151615 as a catalyst. Inventing a method using an alkali metal carbonate or hydrogen carbonate as a catalyst disclosed in JP-A-58-13629, a method using an alkali metal hydroxide as a catalyst disclosed in JP-A-58-67723, and the like, Japanese Patent Application Sho 59-134130
No. 134131 proposes a method using purified sulfolane as a solvent.

Examples of the catalyst used in the similar reaction include alkali metal alkoxides and phenoxides described in U.S. Pat.No. 4061622, alkali metal lactamates described in 4094866, and 4156065 or JP-A-53-92703. The described cyclic phosphorous oxide and the like are also known. In these techniques, as a solvent, a chain or cyclic amide such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, hexamethylphosphoric acid triamide or phosphorylamide, or tetramethylene sulfone, diphenyl Sulfoxides or sulfones such as sulfone and dimethyl sulfoxide, or tetramethylurea are used.

[Problems to be solved by the invention]

However, even in these prior arts, when the diisocyanate and the polycarboxylic acid are reacted at a high temperature in the presence of a polar solvent, the polymer is colored yellow or brown, and there is a problem that the commercial value of the product is reduced. there were. In addition, depending on the specific combination of raw material monomers, the solubility of the produced polymer in the solvent is low, so that a low molecular weight polymer may be precipitated and separated during the polymerization, or the post-treatment process after the completion of the polymerization becomes complicated. There were also problems such as making industrial production difficult. It has been an issue for many years to solve these problems simultaneously and sufficiently.

An object of the present invention is to provide a method for producing a high molecular weight polyamide and / or polyimide having a good hue.

Another object of the present invention is to provide a method for producing a polyamide and / or polyimide in which a low molecular weight polymer is not separated and separated during the polymerization and the post-treatment step after the completion of the polymerization is not complicated.

[Means for solving problems]

The present invention provides the following method for producing polyamide and / or polyimide.

Formula R ¹ (COOH) n (I) [In the formula, R ¹ is absent or is a divalent to tetravalent organic group, and in the case of trivalent, it is ^one of the three carboxyl groups bonded to R ¹ . Two of them are bonded to the position capable of forming an acid anhydride, and in the case of tetravalent, the four carboxyl groups bonded to R ¹ are at the positions capable of forming two sets of acid anhydrides. And n is an integer of 2 to 4. And a polycarboxylic acid represented by], wherein OCN-R ² -NCO (II) [wherein, R ² is a divalent organic group. And a diisocyanate represented by the formula: an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkali metal hydroxide or a formula R ¹ (COOH) 1 (COOM) m (III) [wherein R ¹ is a formula (I) Has the same definition as in 1., l is an integer from 0 to 3, m is an integer from 1 to 4, and l + m is 2 to 4. In producing a polyamide and / or a polyimide by polycondensing at a temperature of 100 ° C. or higher in the presence of one or more alkali metal compounds selected from alkali metal salts of polyvalent carboxylic acids represented by , Expression [In formula, p is 2 or 3. ] The manufacturing method of polyamide and / or polyimide characterized by using the N, N'- dimethylalkylene urea compound represented by these as a solvent.

Polymer produced by the present invention, various heat resistance, heat insulation, radiation resistance, thermal dimensional stability, mechanical properties, electrical properties, chemical resistance further various industrial materials, taking advantage of flame retardancy, etc. It is useful as a high-performance industrial material such as protective material, composite material, reinforcing material, and electrical insulating material, and is used in electric, electronic fields, automobiles, vehicles, aircraft industry fields, clothing and interior fields, and molded articles, films, papers, fibers. It can be widely used for varnishes, adhesives and the like.

The divalent to tetravalent organic group R ¹ in the formulas (I) and (III) and the divalent organic group R ² in the formula (II) are preferably aliphatic groups, aromatic groups, alicyclic groups or Heterocyclic groups, which are groups or atoms that do not substantially react with carboxyl groups and isocyanate groups, such as alkyl groups,
It may be substituted with a cycloalkyl group, an aryl group, an alkoxy group, a halogen atom or the like. Two or more of these groups may be bonded, for example, at carbon-carbon, or may be alkylene, -O-, -S-, And the like (in the formula, R is an alkyl group, a cycloalkyl group or an aryl group, and when two Rs are bonded, they may be different).

Examples of the polycarboxylic acid represented by the formula (I) are described in JP-A-57-
151615, JP-A-57-179223, JP-A-58-13629 and JP-A-58-67723. Examples of n = 2 in the formula (I) are fumaric acid, malonic acid, adipic acid, terephthalic acid, isophthalic acid, diphenyl ether-4,4'-dicarboxylic acid and pyridine-2,6-dicarboxylic acid. . Examples of n = 3 are butane-1,2,4-tricarboxylic acid, benzene-1,2,4-tricarboxylic acid (trimellitic acid), and naphthalene-1,2,4-tricarboxylic acid.
Examples of n = 4 are butane-1,2,3,4-tetracarboxylic acid, cyclobutane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid. Acids (pyromellitic acid), 3,3 ', 4,4'-benzophenone tetracarboxylic acid, and 3,3', 4,4'-dophenyl ether tetracarboxylic acid. These polyvalent carboxylic acids may partially contain an intramolecular acid anhydride group. You may use 2 or more types of polyvalent carboxylic acid.

Examples of the diisocyanate represented by the formula (II) are described in JP-A-57-151615, JP-A-57-179233, JP-A-58-13629 and JP-A-58-67723. Typical examples are 1,2-diisocyanateethane, cyclohexane-1,4
-Diisocyanate, phenylene-1,3-diisocyanate, toluylene-2,4-diisocyanate, toluylene-2,
6-diisocyanate and diphenylmethane-4,4'-diisocyanate. Two or more kinds of diisocyanates can be used.

By combining compounds having various skeletons and bonds as described above as the polyvalent carboxylic acid and diisocyanate represented by the formulas (I) and (II), the processability, chemical and thermal properties of the resulting polymer can be improved. , Electrical properties and mechanical properties can be freely controlled.

Examples of alkali metal carbonates and alkali metal hydrogen carbonates used as catalysts in the process of the present invention are disclosed in JP-A-58.
-13629, potassium carbonate, sodium carbonate, potassium hydrogen carbonate and sodium hydrogen carbonate are particularly preferred.

Further, examples of alkali metal hydroxides used as catalysts are described in JP-A-58-67723, and potassium hydroxide and sodium hydroxide are particularly preferable.

Further, as the alkali metal salt of the polyvalent carboxylic acid represented by the formula (III) used as a catalyst, it is preferable to use one which is industrially and economically advantageous, but similar to the polyvalent carboxylic acid used for polymerization. Particularly preferable effects can be exhibited by using an alkali metal salt of a polycarboxylic acid having the above structure. Examples thereof include mono- and / or di- and / or tri- and / or tetratylium salts of dicarboxylic acids, tricarboxylic acids and tetracarboxylic acids, sodium salts, potassium salts, rubidium salts, cesium salts and francium salts, and more preferably isophthalic acid. Examples thereof include monosodium salt and monopotassium salt of acid or terephthalic acid.

The above-mentioned three kinds of alkali metal compound catalysts have no particular difference in their effects, but in consideration of influences of impurities usually contained in these compounds, the alkali metal salt of the polyvalent carboxylic acid represented by the formula (III) is used. Is preferably used.

Of the above formula (IV) used as a catalyst in the method of the present invention
The N, N'-dimethylalkyleneurea is N, N'-dimethylethyleneurea or N, N'-dimethylpropyleneurea, with N, N'-dimethylethyleneurea being particularly preferred. This solvent needs to be used in a substantially anhydrous state. Other solvents inert to the polymerization reaction, such as benzene, toluene and xylene, can be mixed and used.

In the method of the present invention, a high-molecular weight polyamide having a good hue and / or a polyvalent carboxylic acid and a diisocyanate are used.
Alternatively, the use of the above catalyst is a prerequisite for producing a polyimide, and the use of N, N′-dimethylalkylene urea represented by the above formula (IV) as a polymerization catalyst is an essential requirement. By using the catalyst and N, N'-dimethylalkylene urea solvent in combination, an amide solvent generally used for producing a polyamide from a polycarboxylic acid and a diisocyanate, for example, N-methyl-2-pyrrolidone. Or, N, N- dimethylacetamide and the like, there is no significant coloration that seems to be due to a side reaction with isocyanate, which is a problem, and a polymer with an extremely good hue is produced,
In addition, the combined effect of the catalysts was even better than in the case of using the amide-based solvent, and it became possible to produce a high molecular weight polymer.

In the present invention, the polycondensation reaction temperature is preferably 100 ° C. or higher and not higher than the boiling point of the solvent. At a temperature of 100 ° C or lower, the reaction is not completely completed, and a polymer having a high molecular weight and good thermal stability cannot be obtained. The reaction time is usually 1 to 20 hours. The reaction can be completed at the time when carbon dioxide produced as a by-product is substantially not recognized.

The molar ratio of diisocyanate to polycarboxylic acid is 0.
In the range of 70 to 1.30, particularly preferably in the range of 0.95 to 1.10.

Method of adding raw material monomer and catalyst alkali metal salt,
The order of addition can be arbitrarily selected, but conveniently, they are dissolved in the solvent simultaneously or successively at room temperature. Further, depending on the case, it is possible to continuously add one of the raw material monomers, preferably diisocyanate, at the reaction temperature.

Generally, the concentration of the raw material monomer (polyvalent carboxylic acid + diisocyanate) at the start of the polymerization reaction is selected in the range of 50 to 400 g / l solvent, but the selection of this concentration depends on the reactivity of the raw material monomer and the polymer in the polymerization solvent. It is carried out depending on the solubility and the like. When the polymerization is started at a high concentration, it is preferable to add the solvent continuously or discontinuously in some cases so that the stirring may not be hindered by the increase in viscosity during the polymerization.

Further, the reaction of the present process is de-CO ₂ reaction, moreover CO ₂
Is produced in the form of gas, its removal is extremely easy as compared with the de-HCl or de-H ₂ O reaction between an amino group and an acid halide or acid, and by-products cause side reactions and polymer deterioration. Don't worry.

Further, generally used chemical or physical methods can be used to form an imide bond from the substantially linear high molecular weight polyamic acid obtained by the method of the present invention. It depends on the final form of each. For example, in the case of film and molded products,
A product free from voids can be obtained by careful simultaneous heating in the range of 150 to 350 ° C and removal of condensation water, and when fibers are spun from a solution, heat treatment should be carefully performed or acetic anhydride should be used. Other methods such as addition of a dehydrating agent are used.

〔Example〕

Hereinafter, the method of the present invention will be described with reference to examples, but the present invention is not limited thereto.

In the examples, the logarithmic viscosity (ηinh) is Where t ₀ = flow time of the solvent in the viscometer.

t = flow time of dilute polymer solution in the same solvent in the same viscometer.

C = concentration in grams of polymer in 100 ml of solvent.

Is. In the examples, the concentration was 0.1 g polymer / 100 ml solvent, the temperature was 30 ° C., and 95% concentrated sulfuric acid was used as the solvent unless otherwise specified. In the case of polyamic acid (or partial polyimide), N, N'-dimethylacetamide was used as a solvent.

Example 1 Isophthalic acid 8.3 was added to a 500 ml separable flask equipped with a stirrer, thermometer, condenser, dropping funnel, and nitrogen inlet.
0 g (0.05 mol), terephthalic acid 8.30 g (0.05 mol), isophthalic acid monosodium salt 0.188 g (0.001 mol) and anhydrous N, N'-dimethylethylene urea 370 ml were added, and the oil bath was stirred under nitrogen atmosphere. The contents were completely dissolved by heating above to 200 ° C.

Next, a solution prepared by dissolving 17.76 g (0.102 mol) of toluylene-2,4-diisocyanate / toluylene-2,6-diisocyanate mixture (molar ratio = 80: 20) in 50 ml of anhydrous N, N′-dimethylethyleneurea was added. It dripped over 6 hours from the dropping funnel. The reaction solution remained slightly yellow and increased in viscosity.
After continuing the reaction for another 2 hours, the heating was stopped and the mixture was cooled to room temperature with stirring. A portion of this cooled reaction mixture (about 20
ml) was poured into 500 ml of stirred water in a mixer to precipitate the polymer. After repeating washing with stirring the other polymer with 500 ml of methanol twice,
It was dried at a temperature of 3 ° C. for 3 hours under a reduced pressure of 2 to 3 mmHg to obtain a milky white polymer powder. The ηinh of this product was 2.15.

Comparative Example 1 The reaction was performed in the same manner as in Example 1 except that anhydrous N-methyl-2-pyrrolidone was used instead of the anhydrous N, N′-dimethylethyleneurea of Example 1.

The reaction solution was brownish, the obtained polymer powder was pale yellow, and ηinh was 1.56.

Example 2 16.61 g (0.10 mol) of isophthalic acid, 0.212 g (0.002 mol) of anhydrous sodium carbonate and 370 ml of anhydrous N, N′-dimethylethyleneurea were added to the same apparatus as in Example 1 and stirred in a nitrogen atmosphere. While heating to 200 ° C on an oil bath, the contents were completely dissolved.

Next, a solution prepared by dissolving 17.76 g (0.102 mol) of toluylene-2,4-diisocyanate / toluylene-2,6-diisocyanate mixture (molar ratio = 65: 35) in 50 ml of N, N′-dimethylethyleneurea was added dropwise. It dripped from the funnel over 6 hours. After continuing the reaction for another 2 hours, the heating was stopped and the mixture was cooled to room temperature with stirring.

The cooled reaction solution was poured into 2 of water in the same manner as in Example 1 to precipitate a polymer. Another polymer was washed twice with stirring with methanol twice, and then dried under reduced pressure of 2 to 3 mmHg at 150 ° C. for 5 hours to obtain a milky white polymer powder. The ηinh of this product was 1.95.

Comparative Example 2 The anhydrous N, N'-dimethylethylene urea of Example 2 was converted into N, N '.
-Change the reaction temperature from 200 ° C to 1
The reaction was performed in the same manner as in Example 2 except that the temperature was changed to 60 ° C.

The reaction liquid was brownish, the obtained polymer powder was pale yellow, and ηinh was 0.93.

Example 3 In Example 2, the isophthalic acid was replaced with terephthalic acid, 0.212 g (0.002 mol) of anhydrous sodium carbonate was replaced with 0.204 g (0.001 mol) of monopotassium terephthalate, and N, N'-dimethylethyleneurea was replaced with anhydrous. The reaction was performed in the same manner as in Example 2 except that N, N'-dimethylpropyleneurea was used. A milky white polymer powder was obtained. Ηinh of this thing
Was 2.23.

Example 4 Trimellitic acid 21.0 g (0.10
Mol), 0.188 g (0.001 mol) of monosodium isophthalate and 400 ml of anhydrous N, N'-dimethylethyleneurea, and heated to 160 ° C on an oil bath while stirring under a nitrogen atmosphere to completely dissolve the contents. Let

Next, a solution of 17.59 g (0.101 mol) of toluylene-2,4-diisocyanate / toluylene-2,6-diisocyanate mixture (molar ratio = 80: 20) dissolved in 50 ml of N, N′-dimethylethyleneurea was added dropwise. It dripped from the funnel over 3 hours. After continuing the reaction for another 2 hours, the heating was stopped and the mixture was cooled to 15 ° C with stirring. This solution was poured into 2 cold water in the same manner as in Example 1 to precipitate the polymer.
Another polymer was washed twice with stirring with cold methanol twice, and then dried under reduced pressure of 2-3 mmHg at 100 ° C. for 15 hours to obtain a milky white polymer powder. This thing
When dissolved in DMAc and measured ηinh, it was 1.28.

Example 5 In the same apparatus as in Example 1, 17,90 g (0.05 mol) of 3,3 ', 4,4'-benzophenonetetracarboxylic acid, 0.102 g (0.0005 mol) of monopotassium terephthalate and anhydrous N, N'-dimethyl were used. 370 ml of ethylene urea was added, and the contents were completely dissolved by heating to 160 ° C. on an oil bath while stirring under a nitrogen atmosphere.

Then toluylene-2,4-diisocyanate / toluylene-2,
6-diisocyanate mixture (molar ratio = 80:20) 8.80 g (0.
A solution of 505 mol) dissolved in 50 ml of anhydrous N, N'-dimethylethyleneurea was added dropwise from the dropping funnel over 3 hours. After continuing the reaction for another 2 hours, the heating was stopped and the mixture was cooled to 15 ° C with stirring. This was washed and dried in the same manner as in Example 4 to obtain a milky white powder. This was dissolved in DMAc and measured for ηinh, which was 1.40.

〔The invention's effect〕

According to the present invention, there is no precipitation separation of a low molecular weight polymer during the polymerization, the post-treatment process after the completion of the polymerization is not complicated, and the hue is good, and the substantially linear high molecular weight polyamide and / or A polyimide can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Toyota 2070, Iijima-cho, Totsuka-ku, Yokohama-shi, Kanagawa (72) Inventor Hiromi Nakano 4-10-8, Kuki, Zushi, Kanagawa

Claims (6)

[Claims] 1. A compound represented by the formula R ¹ (COOH) n (I) [wherein R ¹ is absent or is a divalent to tetravalent organic group, and in the case of trivalent, 3 is bonded to R ¹ Two of the carboxyl groups are bound to positions capable of forming an acid anhydride, and in the case of tetravalent, the four carboxyl groups bound to R ¹ are two groups of acid anhydrides. It is bonded to a position where it can be formed, and n is an integer of 2 to 4. And a polycarboxylic acid represented by], wherein OCN-R ² -NCO (II) [wherein, R ² is a divalent organic group. And a diisocyanate represented by the formula: alkali metal carbonate, alkali metal hydrogen carbonate, alkali metal hydroxide or the formula R ¹ (COOH) l (COOM) m (III) [wherein R ¹ is the formula (I) Has the same definition as in, and l is 0
Is an integer of 3; m is an integer of 1 to 4; and l + m is 2 to 4. In producing a polyamide and / or a polyimide by polycondensing at a temperature of 100 ° C. or higher in the presence of one or more alkali metal compounds selected from alkali metal salts of polyvalent carboxylic acids represented by , Expression [In formula, p is 2 or 3. ] The manufacturing method of polyamide and / or polyimide characterized by using the N, N'- dimethylalkylene urea compound represented by these as a solvent. 2. The N, N′-dimethylalkylene urea is
A method according to claim 1 which is N, N'-dimethylethylene urea. 3. The method according to claim 1, wherein the alkali metal compound is an alkali metal salt of an aromatic dicarboxylic acid. 4. The method according to claim 3, wherein the alkali metal salt of aromatic dicarboxylic acid is a monopotassium salt or a monosodium salt of isophthalic acid or terephthalic acid. 5. The alkali metal compound is potassium carbonate,
A method according to claim 1 which is sodium carbonate, potassium hydrogen carbonate or sodium hydrogen carbonate. 6. The method according to claim 1, wherein the alkali metal compound is potassium hydroxide or sodium hydroxide.