JPS61204218A - Production of aromatic polyamide - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having improved hue, crystallizability, and high molecular weight, by subjecting tolyene-2,6-diisocyanate and terephthalic acid to polycondensation in the presence of a specific alkali metallic compound in a solvent of an N,N'-dimethylalkylurea. CONSTITUTION:Tolylene-2,6-diisocyanate and terephthalic acid are subjected to polycondensation in the presence of an alkali metallic carbonate, alkali metallic hydrogencarbonate, alkali metallic hydroxide, or a polyvalent carboxylic acid alkali metallic salt shown by the formula I (R<1> does not exist, or is di--tetrafunctional organic group not to be reacted with carboxyl group and isocyanate group; M is alkali metal; l is 0-3 integer; m is 1-4 integer, l+m is 2-4) in an N,N'-dimethyl-alkylurea compound shown by the formula II (n is 2 or 3) as a solvent at >=100 deg.C, to give a poly(2-methyl-1,3-phenylene terephthalamide).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to poly(2-methyl-1,3-phenylene terephthalamide) [repeating unit structure: [conventional [Technology] It is already known to produce an aromatic polyamide from an aromatic dicarboxylic acid and an aromatic diisocyanate, and generally, an aromatic dicarboxylic acid and an aromatic diisocyanate are mixed in an anhydrous organic polar solvent at room temperature to 250°C. The reaction is carried out at a temperature of 1 to 20 hours. However, this reaction product usually has a lower molecular weight compared to polyamides made from aromatic diamines and aromatic tribasic acid civalides, and often branched or crosslinked polymers are used as reaction products. This ease of formation has created problems in preparing homogeneous and stable polymer solutions from the reaction products, which are then difficult to process into fiber or film form.

In addition, in this conventional technology, when single polycondensation is performed at high temperature,
The resulting polymer was often colored, which caused practical problems in the final product. Furthermore, depending on the specific combination of raw materials and additives, the resulting aromatic polyamide may have low solubility in the solvent, so the polymer may precipitate out of the polymerization solution system before reaching a sufficient high molecular weight during polymerization, or the polymerization may be delayed. There have been problems in that the post-processing process after completion is complicated, making industrial production difficult.

The present inventors have developed a method using an alkali metal salt of a polycarboxylic acid as a catalyst, which was disclosed in JP-A-57-151 Eils as an innovative method for producing high molecular weight polyamide from a polycarboxylic acid and a diisocyanate. , JP-A-58-1
3 [He invented a method using an alkali metal carbonate or hydrogen carbonate as a catalyst disclosed in No. 129, and a method using an alkali metal hydroxide as a catalyst disclosed in JP-A No. 58-67723, and further patent application 5th No. 134130, No. 13413
No. 1 proposes a method using purified sulfolane as a solvent.

Catalysts used in similar reactions include U.S. Pat.
Alkali metal alkoxides and phenoxides described in No. 822, No. 4,094. Alkali metal lactamate described in Be1l1 specification, 4.158,0
Cyclic and phosphorus oxides described in No. 65 or JP-A-53-92703 are also known. In these techniques, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, γ-
linear or cyclic amides or phosphorylamides such as butyrolactone, hexamethylphosphoric triamide;
Alternatively, sulfoxides or sulfones such as tetramethylene sulfone, diphenyl sulfone, dimethyl sulfoxide, or tetramethyl urea are used.

[Problem that the invention seeks to solve]

However, even in these prior art techniques, when diisocyanate and polycarboxylic acid are reacted at high temperature in the presence of a polar solvent, there are problems such as the polymer becoming yellow or brown and reducing the commercial value of the product. there were. There is also the problem that a polymer of sufficiently high molecular weight cannot be obtained depending on a particular combination of raw materials and additives. Solving these problems simultaneously and satisfactorily has been a long-standing challenge.

An object of the present invention is to provide a new method for producing a crystalline, high-molecular-weight aromatic polyamide with good color based on a combination of specific monomers.

[Means for solving problems]

The present invention provides the following method for producing aromatic polyamide.

Tolylene-2,8-diisocyanate and terephthalic acid are combined into an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkali metal hydroxide or an alkali metal hydroxide (%) [wherein R is not present or a carboxyl group and Incyanate groups are divalent to tetravalent organic groups that do not substantially react with each other, and in the case of trivalent organic groups, two of the three carboxyl groups (including GOON) bonded to R1 are acidic. It is bonded to a position that can form an anhydride, and in the case of a tetravalent organic group, the four carboxyl groups (including Cool) bonded to R1 are bonded to a position that can form two sets of acid anhydrides. is bonded to, M is an alkali metal atom.

l is an integer from O to 3, m is an integer from 1 to 4, and J+m is from 2 to 4.

] In the presence of one or more alkali metal compounds selected from alkali metal salts of polyhydric carboxylic acids represented by , 3-phenylene terephthalamide), the solvent has the formula [where n is 2 or 3]. ] A method for producing an aromatic polyamide, which is an N,N'-dimethylalkylene urea compound represented by:

Trilene-2 used as a monomer in the present invention,
6-diisocyanate is generally produced by reacting tolylene-diamine (2,4-diamine/2,8-diamine mixture) with phosgene as a starting material, and is obtained by further purification and separation. Trilene-2,6-
There is also the difficulty of separating diisocyanate and tolylene-2,4-diisocyanate with high purity. However, even if it contains 10 mol% or less of tolylene-2,4-diisocyanate, the physical properties of the resulting polymer are similar to those of poly(2-methyl-1,3-phenylene terephthalamide) and are not satisfactory for practical use. can get.

On the other hand, when copolymerizing isophthalic acid by adding isophthalic acid as a comonomer to the monomer terephthalic acid, if it is 10 mol% or less of terephthalic acid, the physical properties of the resulting polymer will change to poly(2-methyl-1,3 -Phenylene terephthalamide), which is practically satisfactory.

The molar ratio of tolylene-2,8-diisocyanate to terephthalic acid ranges from 0.70 to 1.30, in particular 0.70 to 1.30.
Preferably, the weight is substantially equivalent in the range of 95 to 1.10.

Examples of alkali metal carbonates and alkali metal hydrogen carbonates used as catalysts in the method of the present invention are disclosed in JP-A No. 5
8-1311129, and 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-58-117723, and potassium hydroxide and sodium hydroxide are particularly preferred.

Further, to specifically explain the alkali metal salt of a polyhydric carboxylic acid represented by the above formula CI) used as a catalyst, when R is not present in formula (I), it is an alkali metal salt of oxalic acid.

When R is a di- to tetravalent organic group, this organic group is preferably an aliphatic group, an aromatic group, an alicyclic group, or a heterocyclic group, which is substantially similar to a carboxyl group and an incyanate group. Non-reactive groups and/or atoms 1 may be substituted with, for example, alkyl groups, cycloalkyl groups, aryl groups, alkoxy groups, halogen atoms, etc., or two or more of these groups may be bonded, for example, by carbon-carbon. or alkylene, -o-, -s-, -1.

group or aryl group, which may be different if two are bonded).

Examples of alkali metal salts of polyhydric carboxylic acids represented by formula (I) are disclosed in JP-A-57-151815 and JP-A-59-12.
9ia89, it is preferable to use an alkali metal salt of an acid having a structure similar to terephthalic acid, which is the raw material dicarboxylic acid, because a polymer with a highly homogeneous molecular chain structure can be obtained.

Preference is given to the alkali metal salts of aromatic dicarboxylic acids, especially the monopotassium or monosodium salts of isophthalic acid or terephthalic acid.

There is no particular difference in the effects of the above three types of alkali metal compound catalysts, but considering the influence of impurities normally contained in these compounds, the alkali metal salt of the polyhydric carboxylic acid of formula (I) It is preferable to use

The amount of the alkali metal compound added as a catalyst is preferably 0.10 to 20 mol%, particularly 0.10 to 20 mol%, based on the raw material dicarboxylic acid.
．． 5 to 10 mol% is preferred.

The above formula (rV
) N,N'-dimethylalkyleneurea is N,N'-
This solvent, which is dimethylethyleneurea or N,N'-dimethylpropyleneurea, particularly preferably N,N'-dimethylethyleneurea, needs to be used in a substantially anhydrous state.

Other solvents inert to the polymerization reaction, such as benzene, toluene, xylene, etc., can be used in combination.

In the production of the aromatic polyamide with the specific structure of the present invention, the characteristics of the polymer obtained by polycondensation of tolylene-2,8-diisocyanate and terephthalic acid in the presence of the alkali metal compound and the economic efficiency of the production method were investigated. In order to achieve a satisfactory result, it is essential to use the N,N'-dimethylalkylene urea compound represented by the above formula (II) as a solvent.

In producing poly(2-methyl-1,3-phenylene terephthalamide) from tolylene-2,6-diisocyanate and terephthalic acid according to the present invention, there is a method for adding alkali metal salts to the raw materials and a catalyst. Although the order of addition can be selected arbitrarily, these are conveniently dissolved in the solvent simultaneously or sequentially at room temperature. In some cases, it is also possible to continuously add one of the raw materials, preferably diisocyanate, at the reaction temperature.

In the present invention, the polycondensation reaction temperature is preferably 100°C or higher and lower than the boiling point of the solvent. If the temperature is 100°C or lower, the reaction is insufficiently completed and a polymer with high molecular weight and good thermal stability cannot be obtained. the time is.

Usually 1 to 20 hours. The point at which the by-product carbon dioxide is substantially no longer observed can be regarded as the completion point of the reaction.

According to the method of the present invention, polymer concentrations as high as about 25% by weight can be produced, but the optimum concentration is selected by selecting the desired polymer molecular weight and polymerization temperature. Further, if the polymer solution has a high viscosity and interferes with stirring, it may be diluted with a suitable solvent.

〔Effect of the invention〕

In the method of the present invention, poly(2-methyl-1,3-
The most remarkable effect of using the fulkylene urea compound of Formula 1 (IV) as a solvent when producing crystalline aromatic polyamide (phenylene terephthalamide) is (1)
When the constituent requirements of the present invention are satisfied, the coloring of the obtained polymer is so small that it does not pose a practical problem; (2)
(3) Poly(2-methyl-1,
3-7 enylene terephthalamide) has high solubility in the solvent and can be economically produced at high concentrations.These effects are due to the dissolution of the aromatic polyamide due to the polarity of this solvent. This is based on the strong force and the fact that side reactions between the solvent and the polymerization raw material under polymerization conditions are so small that they can be ignored.

Poly(2-methyl-1,3-phenylene terephthalamide) produced by the present invention is a white linear polymer with a high degree of polymerization, and is used in various textile products and films.

Suitable for manufacturing sheets and paper products. In addition, its excellent heat resistance, heat insulation, radiation resistance, thermal dimensional stability, mechanical properties,
Taking advantage of its electrical properties, chemical resistance, and flame retardancy, it is effective as a high-performance industrial material such as various industrial materials, protective materials, composite materials, reinforcing materials, and electrical insulation materials, and is useful in the electrical and electronic fields, automobiles, Vehicle.

It has great utility in the aircraft industry, consumer clothing, and interior design fields.

〔Example〕

The method of the present invention will be explained below using Examples, but the present invention is not limited by these.

Example 1 Terephthalic acid 25.02 g (0,1508 mol) and terephthalic acid monopotassium salt 0.3074 g (0, 0015
mole).

Anhydrous N,N'-dimethylethyleneurea 830- was placed in a nitrogen atmosphere, and the temperature was raised to 220° C. with stirring on an oil bath. While maintaining the contents at 220°C, torylene-
2,8-diisocyanate 2E1.83g (0,1
A solution of 529 mol) dissolved in anhydrous N,N'-dimethylethylene urea 8011j was added dropwise from the dropping funnel over a period of 2 hours, and the reaction was continued for an additional 2 hours, after which heating was stopped and the mixture was cooled to room temperature.The reaction solution was pale yellow in color. Met. The cooled viscous polymerization liquid was poured into 3 times the volume of strongly stirred water to precipitate the polymer, and after washing thoroughly with a large amount of water, V
The p-separated cake was dried under reduced pressure at 150° C. for about 3 hours to obtain a milky white polymer powder. Logarithmic viscosity of this polymer (95% concentrated sulfuric acid, 0.1%.

(30°C, same hereinafter) was 1.4.

Comparative Example 1 Using the same equipment and method as in Example 1, terephthalic acid 2
A mixture of 5.11 g (0,1511 mol), 0.3080 g (0,0015 mol) of monopotassium terephthalate, and 6301 anhydrous N-methyl-2-pyrrolidone was added to 18
Heating to 0°C, tolylene-2,6-diisocyanate
1.71 g (0,1534 mol) of 2E was dissolved in anhydrous tomethyl-
A solution dissolved in 2-pyrrolidone 60d was added dropwise over a period of 2 hours. The reaction was continued for an additional 2 hours and then cooled to room temperature. The polymer obtained by treatment in the same manner as in Example 1 was yellowish brown and had a logarithmic viscosity of 1.28.

Comparative Example 2 Terephthalic acid 25.08g (0,
1510 mol), anhydrous N,N'-dimethylethylene urea 6301 was heated to 220°C, tolylene-2
,6-diisocyanate 28.811g (0,15
32 mol) of anhydrous N,N'-dimethylethyleneurea 8
A solution dissolved in 0 ml was added dropwise over 2 hours, and the reaction was then continued for an additional 2 hours. A milky white polymer powder was obtained by processing in the same manner as in Example 1. The logarithmic viscosity of this polymer was 0.42.

Example 2 Terephthalic acid 35.1
0g (0,2112 mol), anhydrous sodium carbonate 0.
A mixture of 2238 g (0,0021 mol) of anhydrous N,N'-dimethylpropylene urea 4501 was heated to 220° C. and tolylene-2,6-diisocyanate 37.
82 g (0,21130 mol) Wofi water N, N'-
A solution dissolved in dimethylpropylene urea 30d was added dropwise over a period of 2 hours, and the reaction was continued for an additional 2 hours.The resulting reaction solution was pale yellow and slightly cloudy. A milky white polymer powder was obtained by post-treatment in the same manner as in Example 1.

This polymer had a logarithmic viscosity of 1.3.

From the X-ray diffraction spectrum of this polymer powder, the diffraction angle 2
θ= 18.8°, 19.4@, 21.9°, 2
5.0”.

It was confirmed that the polymer was a crystalline polymer exhibiting a sharp diffraction spectrum at 27.2°.

Further, from the results of differential thermal analysis of this polymer powder, it was determined that this polymer had a glass transition temperature (Tg) of 287°C and a crystal melting peak temperature (Ts) of 454°C.

Claims (1)

[Claims] 1. Trilene-2,6-diisocyanate and terephthalic acid are combined into an alkali metal carbonate, an alkali metal hydrogen carbonate,
Alkali metal hydroxide or a divalent to tetravalent compound of the formula R^1(COOH)_l(COOM)_m(I) [wherein R^1 is absent or does not substantially react with carboxyl groups and isocyanate groups In the case of a trivalent organic group, two of the three carboxyl groups (including COOM) bonded to R^1 are bonded to positions that can form an acid anhydride. In the case of a tetravalent organic group, the four carboxyl groups (including COOM) bonded to R^1 are bonded to positions that can form two sets of acid anhydrides, and M is an alkali. It is a metal atom, l is an integer of 0 to 3, m is an integer of 1 to 4, and l+m is 2 to 4. ] In the presence of one or more alkali metal compounds selected from the alkali metal salts of polyhydric carboxylic acids represented by , 3-phenylene terephthalamide), the solvent has the formula ▲ Numerical formula, chemical formula, table, etc. ▼ (II) [In the formula, n is 2 or 3. ] A method for producing an aromatic polyamide, which is an N,N'-dimethylalkylene urea compound represented by: 2. The N,N'-dimethylalkylene urea is N,N
'-dimethylethylene urea Claim 1
The method described in section. 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 method according to claim 1, wherein the alkali metal compound is potassium carbonate, 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.