JPS627732A - Production of wholly aromatic polyamide carrying pendant primary amino group - Google Patents

Abstract

PURPOSE:To obtain in an industrially stable manner the titled polyamide suitable for, e.g., adhesivity enhancer for aramid fiber, by polymerization between a substituted nitro group-carrying aromatic dicarboxylic acid dichloride and aromatic diamine followed by reduction of the nitro group. CONSTITUTION:First, a pendant nitro group-carrying wholly aromatic polyamide is prepared by low-temperature polymerization, in the presence of, e.g., an acid acceptor (e.g., alkali metal carbonate) and water, between (A) a 6-22C (constituted by 1-3 aromatic ring) aromatic dicarboxylic acid dichloride carrying 1-2 substituted nitro group per molecule (e.g., 2-nitroterephthaloyl chloride) and (B) an aromatic diamine (e.g., p-phenylenediamine). The objective polyamide can be obtained by reduction, using a reducing agent (e.g., sodium hydrosulfite), in a medium such as water, of said aromatic polyamide. If desired, the component A may be incorporated with 0-50mol% of a nitro group-free analogue thereof.

Description

[Detailed Description of the Invention] a. Industrial Application Fields Fully aromatic polyamides having pendant primary amino groups have been proposed for use as curing agents for epoxy resins and membrane materials for reverse osmosis membranes. There is. According to the research conducted by the present inventors, the aramid fiber is also useful as an adhesion improver between the fiber and the matrix resin when the aramid fiber is used as a reinforcing fiber in a composite material. The present invention provides a method for industrially stably producing such useful polyamides.

b. Prior art A method for producing a wholly aromatic polyamide having a pendant primary amino is to protect the amino group by -H acetylation of one amino group of an aromatic poly(e.g., tri)amine, and then protect the amino group with aromatic acid. A known method is to react with chloride to form an aromatic polyamide, then remove the binder 113 and amine it.

C1 Object of the Invention The present invention provides a method for industrially stably producing a vedant primary amino-containing wholly aromatic polyamide, which has conventionally been difficult to produce industrially.

d1 Structure of the Invention The present invention relates to an aromatic dicarboxylic acid dichloride having 1 to 2 substituted nitro groups per molecule directly connected to an aromatic nuclear carbon atom, or a mixture thereof with an aromatic dicarboxylic acid dichloride having no nitro group. and an aromatic diamine: low-temperature polymerization in the presence of an acid acceptor to form a fully aromatic polyamide having pendant nitro groups; thereafter, the nitro groups are reduced to amine groups. This is a method for producing a wholly aromatic polyamide having groups.

In the present invention, an aromatic dicarboxylic acid dichloride having 1 to 2 substituted nitro groups per molecule directly connected to an aromatic nuclear carbon atom refers to an aromatic dicarboxylic acid dichloride having 1 to 3 aromatic rings and having 6 carbon atoms.
It has ~22 aromatic groups, two carboxylic acid chloride groups (-cocl) directly attached to them, and 1 to 2 nitro groups, and it has an inert substituent such as a lower alkyl group. You can leave it there.

Specific examples of such compounds include 2-nitroterephthalic acid chloride, 5-nitroisophthalic acid chloride, 2-nitroterephthalic acid chloride,
-Nitro-5-methylterephthalic acid chloride, 4-nitronaphthalene-2,6-dicarboxylic acid chloride, 2
-Nitro-4,4'-oxydiphenylenedicarboxylic acid dichloride, 2-nitro-14,3'-oxydiphenylenedicarboxylic acid dichloride, 2,6-sinitro-4,4'-oxydiphenylenedicarboxylic acid dichloride.

1.3-bis(4-chloroformylphenyloxy)=2
．． 6-cinitrobenzene and the like can be mentioned.

From an industrial point of view, mention may be made in particular of 2-nitroterephthalic acid chloride and 5-nitroisophthalic acid chloride. These can be obtained in high yields by nitrating terephthalic acid or isophthalic acid, which is produced in large quantities industrially, with a mixed acid and then converting it into the corresponding acid chloride using a conventional method, for example, using phosphorus pentachloride or thionyl chloride. be able to.

In the present invention, the aromatic dicarboxylic acid dichlorite that does not have a nitro group and is optionally used together with the above-mentioned nitro group-containing aromatic dicarboxylic acid dichloride is an aromatic dicarboxylic acid dichlorite having 6 to 22 carbon atoms and having 1 to 3 aromatic rings. It has a group group and two carboxylic acid chloride groups directly connected to it, and includes a lower alkyl group, a lower alkoxy group,
It may have an inert substituent such as a halogen atom.

Suitable examples of such aromatic dicarboxylic acid dichloride include terephthalic acid chloride, isophthalic acid chloride, 2-methylterephthalic acid chloride, naphthalene-2,6-dicarboxylic acid dichloride, 4.4'
-oxydiphenylene dicarboxylic acid dichloride,
4.3'-oxydiphenylenedicarboxylic acid dichloride, 3.3'-diphenylmethanedicarboxylic acid dichloride, 4.3'-benzophenonedicarboxylic acid silolide, 1,4-bis(4-chloroformylphenyloxy)-benzene, etc. can be mentioned.

Particularly useful from an industrial point of view are terephthalic acid chloride and isophthalic acid chloride. Such a dicarboxylic acid chloride can be obtained by converting the corresponding dicarboxylic acid into acid chloride using a conventional method.

Such a dicarboxylic acid dichloride that does not have a nitro group is added to adjust the content of pendant amino groups in the target wholly aromatic polyamide, and if a suitable amino group content is determined depending on the application, it can be added according to the content. Just add it.

Generally, it is used in a range of 0 to 50 mol % based on the total dicarboxylic acid components.

Next, the aromatic diamine used in the present invention refers to a divalent aromatic group having 1 to 3 aromatic rings, a divalent aromatic group having 6 to 22 carbon atoms, and a primary amino group and/or lower alkyl group directly connected thereto. It has a total of two group-substituted secondary amino groups, and the aromatic group may have an inert substituent such as a lower alkyl group, a lower alkoxy group, or a halogen atom.

Six preferred examples of such aromatic diamines include p-phenylene diamine and m-phenylene diamine.

2.4-toluylenediamine, 2-chloro-p-phenylenediamine, 4-methoxy-1,3-phenylenediamine, 4.4'-diaminodiphenylmethane,
4.4'-diaminodiphenyl ether.

3,4'-diaminodiphenyl ether, 3.3
' -diaminodiphenylsulfone, 4.4' -
Examples include diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 1,4-bis-(4-aminophenoxy)benzene.

Particularly preferred from an industrial standpoint are p-phenylenediamine and m-phenylenediamine.

3.4'-diaminodiphenyl ether, 4.4
'-diaminodiphenyl ether and the like.

Such diamines may be used alone or in combination of two or more.

Furthermore, in the present invention, other than the dicarboxylic acid dichloride and diamine described above, small amounts of other polymerization components can also be used within a range that does not impair the properties of the polymer of the present invention.

The reaction between the dicarboxylic acid dichloride and the diamine is carried out in the presence of an acid acceptor by a method known as low-temperature polymerization. That is, preferred examples include ether-based or ketone-based, which are at least partially miscible with water, in the presence of water and an inorganic acid acceptor such as an alkali metal carbonate and/or bicarbonate. A so-called interfacial polymerization method in which low-temperature polymerization is carried out using a non-active solvent: and N-methylpyrrolidone.

Examples include a low-temperature solution polycondensation method in which a polycondensation reaction is carried out in an aprotic polar solvent, the preferred examples of which are so-called amide solvents such as N,N-dimethylacetamide and N,N'-dimethylethyleneurea.

According to the former method, the polyamide produced is generally obtained in the form of a powder, and according to the latter method, the polyamide produced is generally obtained in the form of a solution because the amide solvent used is a good solvent for aromatic polyamides.

The degree of polymerization of the resulting polymer can be adjusted appropriately depending on the intended use, since it is easy to produce a polymer with a sufficiently high degree of polymerization (eg, intrinsic viscosity of 1 to 3).

The method of reducing the nitro groups of the wholly aromatic polyamide having pendant nitro groups thus obtained to form amine groups involves selecting appropriate conditions from conventionally known reduction methods, taking into account that the compound to be reduced is a polymer. can be selected.

A particularly preferred embodiment is a method in which an amide solvent solution of a polyamide having pendant nitro groups obtained by the low-temperature solution polycondensation method is used as it is to reduce the polyamide to amino groups. That is, a method in which a catalytic hydrogenation catalyst such as palladium charcoal or platinum charcoal is added to the solution and catalytic hydrogenation is carried out using normal pressure or pressurized hydrogen gas; at least hydrogen chloride produced as a by-product during the polycondensation reaction is A method of partially utilizing hydrogen chloride and reducing it using metals such as iron, zinc, and tin: A method of neutralizing by-product hydrogen chloride and then adding water and sodium hydrosulfite under neutral conditions for reduction. be able to.

Although the reducing agent itself is expensive, the last method is suitable for small-scale production because the reduction reaction can be carried out under very mild conditions and the product can be easily separated.

On the other hand, when the polymer is obtained in powder form (porous fine powder form) as in the interfacial polycondensation method, it can be reduced in a non-uniform state without being redissolved. For example, the above-mentioned sodium hydrosulfite! in a medium such as water or a water-alcohol system! A method of reducing using a reducing agent such as .

The polyamides having pendant amino groups thus obtained are generally N-methylpyrrolidone, dimethylformamide, dimethylacetamide, tetramethylurea, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, tetramethylurea, N
It is soluble in many aprotic polar solvents such as , N'-dimethylethylene urea and dimethyl sulfoxide, and can be easily coated from these solutions and formed into films, membranes, etc.
It is possible to form it into a fibrous form.

Therefore, the polyamide having pendant amino groups obtained by the present invention is not only suitable for use as a molded article itself as described above, but also as a curing agent for epoxy resins and a membrane material for reverse osmosis membranes, and is also suitable for use as a fiber. It can be thinly coated on the surface of aramid fibers used as reinforcing fibers in reinforced composite materials, or blended into the fibers to improve adhesion with matrix resins such as epoxy resins, unsaturated polyester resins, polyimide resins, and phenolic resins. It is also possible to strengthen it.

The present invention will be explained in more detail below with reference to Examples.

Example 1 2-Nitroterephthalic acid 97.3 g of nitroterephthalic acid and 215 g of phosphorous pentachloride were mixed in a dry nitrogen stream in a 3-tube flask equipped with a roller stirring blade. The reaction proceeded rapidly with the generation of hydrogen chloride gas, forming a homogeneous solution.

- After leaving to stand under a stream of dry nitrogen overnight, phosphorus oxychloride was distilled off while still present. Then, 2-nitroterephthalic acid chloride was obtained by vacuum distillation (180-b/1-8 mH (1)).

3 in a dry nitrogen stream in a 3-tube flask equipped with a stirring blade.
．． 15 N-methylpyrrolidone obtained by dehydrating 9.062 g of 4'-diaminophenyl ether with molecular sieves
Dissolved in 0d.

The solution was externally cooled with ice water, 2-nitroterephthalic acid chloride 11.8869 was added, and poly-3,4'
-Oxydiphenylene(2-nitro)terephthalamide was prepared.

Hydrogen chloride in the above polymer solution was added to lithium carbonate by 11.
After neutralizing by adding 3SF, 5.6 g of water and hydrosulfide (Na 2 S20< ) 41.7! iF was added to reduce the pendant nitro groups of the polymer to amine groups.

The reaction mixture was precipitated with water to obtain poly-3,4'-oxydiphenylene(2-amine)terephthalamide in powder form.

The aforementioned 3,4'-diaminodiphenyl ether and 2
- By changing the molar balance with nitroterephthalic acid chloride, it was possible to control ηinh = 0.3 to 3.5.

[Brief explanation of the drawing]

FIG. 1 is an IR chart of poly-3,4'-oxydiphenylene (2-amine) terephthalamide obtained in Example 1. Purification of the drawings (no change in content) Procedural amendment (flag) 1. Case indication patent application No. 1987-145729 2. Title of the invention

Claims (1)

[Claims] 1 substituted nitro group directly attached to an aromatic nuclear carbon atom per minute.
An aromatic dicarboxylic acid dichloride having ~2 or a mixture thereof and an aromatic dicarboxylic acid dichloride having no nitro group and an aromatic diamine; low temperature polymerization in the presence of an acid acceptor to produce a fully aromatic product having a pendant nitro group. A method for producing a wholly aromatic polyamide having pendant primary amino groups, characterized in that the nitro groups are then reduced to amino groups.