JPS58173130A - Production of novel transparent polyamide - Google Patents

Abstract

PURPOSE:To produce, at low cost, a polyamide which does not lose transparency upon contact with hot water and is excellent in transparency and mechanical properties, by reacting an isophthalic acid (derivative) with a specified diamine. CONSTITUTION:A transparent polyamide is produced by using a diamine component and a dicarboxylic acid component which are industrially and inexpensively available in quantity. Namely, (A) a diamine component containing at least about 85mol% 2,5-dimethylhexamethylenediamine (the balance comprising hexamethylenediamine, for example) is polycondensed with (B) a dicarboxylic acid component containing at least about 85mol% isophthalic acid (derivative) (the balance comprising terephthalic acid, for example) at above about 200 deg.C under an elevated pressure.

Description

[Detailed description of the invention] The present invention relates to a method for producing transparent polyamide.

In particular, the present invention relates to a method for inexpensively producing a polyamide that does not devitrify due to hot water and has excellent transparency and good mechanical properties.

Conventionally, as a method of producing transparent polyamide.

For example, a method using 2,2,4-) dimethylhexamethylene diamine as a diamine raw material (Japanese Patent Publication No. 44-1987
0 and Japanese Patent Publication No. 49-21115), and a method using 3-aminomethyl-3,5,5-)dimethylcyclohexylamine (Japanese Patent Publication No. 43-6072). However, because these transparent polyamides use extremely special diamines that cannot be obtained industrially at low cost as raw materials, they cannot be provided industrially advantageously as molding materials, and there is a gap in the development of applications. It has become. Furthermore, the transparent polyamide obtained using 2,2,4-) dimethylhexamethylene diamine has the disadvantage that crystallization gradually progresses in hot water, resulting in whitening and devitrification.

On the other hand, a method for producing transparent polyamide using 2,5-dimethylhexamethylene diamine, which can be produced advantageously industrially, in combination with naphthalene dicarboxylic acid as a dicarboxylic acid raw material component was also proposed (West German Patent No. 1,
No. 254,347). However, the polyamide obtained in this manner is expensive because it uses expensive raw materials.

Since the processing temperature is high, it has drawbacks such as a lack of melt thermal stability during processing, and is not necessarily satisfactory.

The present inventors have conducted extensive research to overcome the drawbacks of conventional transparent polyamides and to develop an industrially advantageous method for producing polyamides that have stable transparency and excellent physical properties. As a result of stacking, 2,
It was discovered that the object could be achieved by incorporating 5-dimethylhexamethylene diamine with isophthalic acid as the dicarboxylic acid component, and based on this knowledge, the present invention was accomplished.

Specifically, the present invention provides a transparent polyamide characterized by reacting a diamine component mainly composed of 2,5-dimethylhexamethylene diamine with a dicarboxylic acid component mainly composed of inphthalic acid or its reactive acid derivative. A manufacturing method is provided.

All of the raw material components used in the method of the present invention are supplied in large quantities and at low cost as industrial raw materials. For example, 2,5-dimethylhexamethylene diamine is used as a diamine component.

It is easily produced by electrolytic trimerization of azilonitrile and hydrogenation.

Furthermore, isophthalic acid and its reactive acid derivatives used as the dibasic acid component in the method of the present invention are compounds widely used as raw materials for various polyamides and raw materials for various polyesters.

It is an industrially extremely advantageous raw material component.

The diamine component used in the method of the present invention needs to be a diamine mainly composed of 2,5-dimethylhexamethylene diamine. Preferably, the mole percent is 2,5-dimethylhexamethylene diamine.

Examples of other diamines that can be used in combination with this include hexamethylene diamine, bis(4-aminocyclohexyl)methane, diaminobenzene, and xylylene diamine. These can be used alone or in combination with 2,5-dimethylhexamethylene diamine.

Furthermore, the dibasic acid component used in the method of the present invention is as follows.

Lucicarboxylic acid components based on isophthalic acid or reactive acid derivatives thereof, preferably at least 85 mole % based on the total dicarboxylic acid components.

As the functional acid derivatives of isophthalic acid which form polyamides, mention may be made of acid halides such as isophthalic acid dichloride, alkyl esters or aryl esters such as dimethyl inphthalate.

Comonomers that can be used in combination with these include terephthalic acid, succinic acid, and adipic acid.

Examples include dibasic acid compounds such as sebacic acid and dodecanedicarboxylic acid, and lactam compounds such as caprolactam and lauryllactam can be added to the reaction system and introduced into the polyamide.

For the polycondensation of the L diamine component and dibasic acid component in the production of the transparent polyamide of the present invention, any reaction method commonly used in the production of known polyamides containing diamine residues and dicarboxylic acid residues may be used. Can be adopted.

For example, a concentrated aqueous solution of a salt of 2,5-dimethylhexamethylenediamine and isophthale is added under pressure to
A method of heating polycondensation at a temperature of 0' C or lower, or a method of dissolving an equimolar amount of the image component compound in hot water, and then heating and polymerizing it under pressure at high temperature, Polyamide can be easily produced by a method such as solution polymerization or interfacial polycondensation of dimethylhexamethylene diamine at room temperature.

The polyamide obtained by the method of the present invention is transparent and devitrified even when immersed in hot water for a long time, like the transparent polyamide obtained using 2,2,4-trimethylhexamethylene diamine. No phenomena were observed, and it is an extremely desirable plastic material with excellent physical properties, especially mechanical strength.

In addition, since restarting raw materials can be easily obtained at low cost, it is extremely advantageous industrially.1 The present invention has great practical value.

Since the transparent polyamide according to the present invention has the above-mentioned excellent properties, it can be conveniently used in, for example, flowmeters, speedometer covers, gas lighters, A hour=+ covers, sight windows, fuse distribution board covers, etc. be able to.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 2.5-dimethylhexamethylenediamine 2.6g,
Isophthalic acid 3. OKf and 5.7 kg of water were placed in a 201 autoclave, heated to 220°C, and the internal pressure was increased to 17.5 kg.
The temperature was raised to 280° C. while maintaining the temperature at Kg/c4.

After maintaining the temperature for 2 hours, the pressure was gradually released and polycondensation was allowed to proceed for 1 hour at atmospheric pressure in a nitrogen atmosphere. The obtained polyamide was transparent and colorless, and the specific viscosity of an 8.4% by weight solution using formic acid as a solvent was 30. This polyamide is S
After drying for 24 hours under reduced pressure of O'c% lmHg,
Using a 1 oz injection molding machine, the cylinder temperature was 230°C.
ASTM No. 1 dumbbell test pieces were molded at a mold temperature of 80°C and subjected to physical property measurements. As a result, the tensile strength was 750
A value of 9/i and an elongation of 60% were obtained. Further, this test piece was immersed in hot water at 80°C for 30 days, but no change in transparency was observed. In contrast, Trogamid T (manufactured by Dynamite Nobel, 2
, 2.4-) in transparent polyamides such as dimethylhexamethylene diamine and terephthalic acid).

Under the same immersion conditions, partial whitening occurred and a decrease in transparency was observed.

Example 2 Polycondensation was carried out in the same manner as in Example 1 except that 10 mol% of isophthalic acid was replaced with terephthalic acid. The obtained polyamide was transparent, and the specific viscosity of an 8.4% by weight solution using formic acid as a solvent was 35. No change in transparency was observed even after immersion in hot water at 80°C for 30 days.

Example 3 10 mol% of 2.5-dimethylhexamethylene diamine
Polycondensation was carried out in the same manner as in Example 1, except that hexamethylene diamine was used instead of hexamethylene diamine. The obtained polyamide was transparent, and the specific viscosity of an 8.4% by weight solution using formic acid as a solvent was 30. No change in transparency was observed even after immersion in hot water at 80°C for 30 days.

Example 4 2.5-Dimethylhexamethylenediamine l, sKg.

Sodium hydroxide soo f! - was dissolved in 25 liters of water.

While vigorously stirring this aqueous solution, cyclohexanone lO6 containing 2.1 Kf of isophthaloyl chloride was added dropwise and stirred for 30 minutes. The polymer suspension was poured into a large amount of acetone, and the polymer was then filtered out. The polymer was washed repeatedly with hot water and dried. The obtained polyamide was colorless and transparent.8.
The specific viscosity of the 4% by weight solution was 35.

Patent applicant: Asahi Kasei Industries, Ltd. Agent Akira Agata

Claims (1)

[Claims] A method for producing a transparent polyamide, which comprises reacting a diamine component mainly composed of 2,5-dimethylhexamethylene diamine and a dicarboxylic acid component mainly composed of isophthalic acid or its reactive acid derivative.