JPH03126725A - Production of copolyamide - Google Patents

Abstract

PURPOSE:To stably obtain an aromatic amide having high rigidity, low water absorption and excellent gas barrier properties in subjecting a dicarboxylic acid component to hexamethylenediamine to polycondensation by polymerizing the components in the presence of sodium hypophosphite in a specific ratio. CONSTITUTION:In subjecting (A) adipic acid, terephthalic acid and isophthalic acid as dicarboxylic acid components and (B) hexamethylenediamine as a diamine component to polycondensation, (C) 1/5,000-1/100mol sodium hypophosphite based on number of total mols of the dicarboxylic acid or the diamine is added to the components, which are polymerized to give an aromatic copolyamide having <=2.5X10<-5> equivalent/g terminal group concentrations of amino and/or carboxyl group at both terminal groups and 1.9-4.0 relative viscosity etarel by sulfuric acid solution method.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to the use of dicarboxylic acids obtained by copolymerizing hexamethylene diamine with dicarboxylic acids consisting of adipic acid, terephthalic acid, and isophthalic acid components. The present invention relates to a method for producing an aromatic copolyamide without impairing the excellent properties of the aromatic copolyamide, preventing gelation during polymerization, and without abnormally increasing the melt viscosity.

(Prior art) Polycapramide, polyhexamethylene diamine, etc. are highly crystalline polyamides that can be easily melt-molded, so they are widely used in clothing or industrial fibers, textiles, films, monofilaments, engineering plastics, etc. There is.

Although this polyamide molded article has excellent mechanical properties, it has the drawbacks of poor dimensional stability due to its low Young's modulus and low glass transition point and high hygroscopicity.

In order to overcome this drawback, various attempts have been made to introduce rigid aromatic components such as terephthalamide units into the main chain of the polymer as copolymerized units. A copolymer using hexamethylene diamine as the diamine component and adipic acid, terephcuric acid, and isophthalic acid as the dicarboxylic acid component as monomers is made into an aqueous solution of equimolar amounts of their salts or diamine component and dicarboxylic acid component, and heated under pressure. It is possible to obtain polyamides that can be produced by the usual polyamide polymerization method of melt polymerization, and that have different glass transition points, melting points, transparency, hygroscopicity, etc. depending on the proportions of adipic acid, terephthalic acid, and isophthalic acid as dicarboxylic acid components. Can be done.

However, when polymerizing polyamide containing a phthalic acid component, the melt viscosity of the polymer has conventionally increased significantly,
Industrially, it has been difficult to make product chips due to problems such as difficulty in discharging from the polymerization tank and gelation during polymerization.

That is, an aromatic copolyamide (hereinafter referred to as 66/6 T6 copolyamide) using hexamethylene diamine as a diamine component and adipic acid, terephthalic acid, and isophthalic acid as monomer components as dicarboxylic acid components.
During copolymerization, it may be difficult to discharge the polymer from the polymerization tank due to its high viscosity, and gelation may occur during polymerization, or the discharged polymer may contain a large amount of air bubbles, resulting in poor discharge stability or When melt-molding the obtained polymer, there were problems such as fluctuations in melt viscosity and the inability to obtain a polymer with stable mechanical properties, so that it could not be implemented industrially.

(Problems to be Solved by the Invention) The present invention solves the above problems and achieves a stable melt viscosity of 66/6 T/6 without deteriorating the quality of the polymer.
The main object of the present invention is to provide a method for industrially easily producing I copolyamide.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the inventors of the present invention have made extensive studies and have arrived at the present invention. That is, in the present invention, when polycondensing a dicarboxylic acid component consisting of the three components of adipic acid, terephthalic acid, and isophthalic acid with hexamethylene diamine, sodium hypophosphite is added to The aromatic copolyamide obtained by polymerization by adding 15,000 to 1/100 mol] has a terminal group concentration of either or both of amino groups and carboxyl groups at both ends.
．． This is a method for producing an aromatic copolyamide having a relative viscosity ηreJ of 5×10 −5 equivalent/g or less and a relative viscosity ηreJ of 1.9 to 4.0 by a sulfuric acid solution method.

In the aromatic copolyamide of the present invention, when copolymerizing hexamethylene diamine as the diamine component and adipic acid, terephthalic acid, and isophthalic acid as the dicarboxylic acid components, the copolymerization ratio of the resulting 66/6T/6I copolyamide is arbitrary. can be selected. for example,
In order to increase the melting point and glass transition point, it is preferable to increase the copolymerization ratio of terephthalamide units, and in order to increase transparency, it is preferable to increase the copolymerization ratio of isophthalamide units. Furthermore, the thermoabsorption of the molded article can be reduced by increasing the copolymerization ratio of terephthalamide and isophthalamide units.

The method of warming the starting materials prior to polymerization is not particularly limited. That is, a method in which a single salt is prepared in advance from each diamine and dicarboxylic acid and mixed in a predetermined amount during polymerization, and a diamine aqueous solution containing a predetermined amount of hexamethylene diamine is added with a predetermined amount of adipic acid and terephthalate under heating. Any method can be used, such as adding and mixing acid and isophthalic acid to form a nylon salt aqueous acid.

The terminal group regulator used to adjust the concentration of either the amino group or the carboxyl group or both at both ends of the copolyamide finally obtained to 2.5×11' equivalent/g or less is an aliphatic Dicarboxylic acid, aromatic dicarboxylic acid, aliphatic monocarboxylic acid, aromatic monocarboxylic acid, aliphatic diamine, aromatic diamine, aliphatic monoamine, aromatic monoamine, etc. Molecular weight used in the polymerization of ordinary nylon 6 and nylon 66, etc. A regulator may be used alone or in combination.

The amount of the end group concentration regulator added is not particularly limited. That is, the relative viscosity η of the copolyamide finally obtained. 1 in 98% concentrated sulfuric acid, 1 g/dl concentration,
The polymer must have a concentration of 1.9 to 4.0 at 25°C, and either or both of the amino group concentration or carboxyl group concentration at both ends must be 2.5X10-5 equivalent/g or less. This is essentially important, and since the reactivity with the polymer constituents differs depending on the type of end group concentration adjusting agent, it is important to specify the amount added depending on the type of end group concentration adjusting agent used. For example, when acetic acid is used, it is 1/100 to 1/30 of the number of moles charged in the polymer component (total number of moles of dicarboxylic acid or diamine).
Preferably 0 mol of acetic acid is added, in the case of stearic acid 1/
It is preferable to add 70 to 1/20 mol.

Next, the amount of sodium hypophosphite used in the present invention is 115,000 to 115,000 to the number of moles of the polymer components charged.
1/100 mole is preferable, more preferably 1/200
It is 0 to 11,500 moles. In a system in which sodium hypophosphite is not added, the relative viscosity ηrel increases abnormally even if the end group concentration of the final polymer is 2.5X10-5 equivalent/g or less, and the objective of the present invention is It is not possible to obtain a polymer with

When polymerizing 66/6 T/6 ecobolyamide under conditions that satisfy the above structural requirements, the polymerization may be performed under reduced pressure at the final stage of polymerization. Further, during polymerization, in addition to the above-mentioned components, heat resistant agents, weather resistant agents, light stabilizers, antifoaming agents, plasticizers, etc. may be added.

The method of the present invention can be applied to either batch or continuous polymerization.

(Example) EXAMPLES Below, the present invention will be specifically explained with reference to Examples.

Examples 1 to 5 and Comparative Example 1.2 Using a small pressurized polymerization tank, 66/6 T/61 components,
Regarding end group concentration regulator and sodium hypophosphite,
Polymerization was carried out using the types and amounts shown in Table 1. For polymerization, each salt is first prepared, and after purification, predetermined amounts of an end group concentration regulator and sodium hypophosphite are added, and then water is added at 18% of the amount of polymer components charged.
% by weight was added. The polymerization method is to completely replace the inside of the container with N2, heat the container with a mantle heater, and raise the pressure to 17.
5 kg/cm2.2], and was subjected to pressure polymerization at 0°C for 3 hours. After that, lower the pressure and keep it at 240°C for 6 hours at normal pressure.
, post-polymerization was performed, and the polymer was discharged as a strand into water from a nozzle at the bottom of the polymerization tank. The strands were pelletized using a pelletizer, dried under reduced pressure under heat, and evaluated as described below. The results are shown in Table 1.

(1) Measurement of ηrel According to the sulfuric acid solution method of JIS K6810, the concentration was 1 g/a in 98% concentrated sulfuric acid! , measured at 25°C.

(2) Quantification of terminal amino group concentration The produced copolyamide was dissolved in phenol and titrated with 05N hydrochloric acid.

(3) Quantification of terminal carboxyl group concentration Dissolving the produced copolyamide in benzyl alcohol,
Titrated with 0.05N caustic soda.

(4) Evaluation of discharge stability After polymerizing the copolyamide, the polymer strand discharged from the polymer extraction nozzle at the bottom of the polymerization tank was visually observed to evaluate discharge stability. The evaluation criteria were as follows: 0 if the polymer could be stably removed, poor if the polymer could not be discharged due to abnormal increase in viscosity or gelation, and poor if the polymer contained air bubbles and unstable string removal.

Example 6 Example 1 was carried out, except that the postpolymerization was carried out at a temperature of 290'C. The results are shown in Table 1.

Comparative Example 3 The same procedure as Example 1 was carried out except that the post-polymerization reaction time was 38 r. The results are shown in Table 1.

1 [Effect of the invention] As described above, by using the method of the present invention,
It has now become possible to stably produce 6 6/6 T/6 I copolyamide, which has high rigidity, low water absorption, and poor gas barrier properties, by an industrial polymerization method.

Claims (1)

[Claims] When polycondensing a dicarboxylic acid component consisting of three components of adipic acid, terephthalic acid, and isophthalic acid with hexamethylene diamine, add sodium hypophosphite to the number of moles of monomer components (total number of moles of dicarboxylic acid or diamine). The aromatic copolyamide obtained by polymerization by adding 1/5000 to 1/100 mol has an amino group or a carboxyl group at both ends, or a terminal group concentration of 2.5 x 10^-^5 equivalent/ A method for producing an aromatic copolyamide having a relative viscosity ηrel of 1.9 to 4.0 in a sulfuric acid solution method.