CS219661B1 - Polymerization mixture for preparation of the polyamide-4 - Google Patents

Abstract

Polymerization mixture for the preparation of polyamide-4 i from 2-pyrrolidone and alkali salt of 2-pyrrolidone,, especially for the preparation of fibers containing not more than 0.4 mmol of 4-aminobutanoic acid alkaline salt per gram of polymerization mixture, wherein molar the alkali salt of 2-pyrrolidone and alkali salt 4-aminobutanoic acid is 2 to 9

Description

The invention relates to a polymerization mixture for the preparation of polyamide-4 from 2-pyrrolidone and a base, in particular for the production of fibers.

Methods for polymerizing 2-pyrrolidone to produce polypyrrolidone have been described above. For example, U.S. Patent 2,889,958 describes the polymerization of 2-pyrrolidone in the presence of an alkaline polymerization catalyst, optionally in the presence of an activator.

According to the basic US patent 3,721,652, which protects the process of preparing polyamide-4 in more than 20 countries, alkali metal derivatives, e.g. j. alkali metal hydroxides and oxides. Alkali metal alcoholates as well as sodium methylate can also be used with good results. In addition, strongly basic organic metal compounds such as butyl lithium may be used.

Acetyl-pyrrolidone, adipyl-pyrrolidone or organic isocyanates can be used as polymerization activators. For the preparation of melt-spun polyamide-4, it is recommended to use carbon dioxide as a polymerization activator - Pat. USA 2,638,463.

U.S. Pat. No. 3,683,046 discloses a protected combination of carbon dioxide with N-acyllactam type activators added to the system in an amount of 0.6 to 7 mmol per mole of 2-pyrrolidone with the addition of a fine-grained material.

Up to now, it has not been known that by preparing an 2-pyrrolidone polymerization initiator by reacting an alkali metal base with 2-pyrrolidone to form the 2-pyrrolidone alkali salt, the alkali salt of 4-aminobutyric acid is formed as a byproduct by hydrolysis of 2-pyrrolidone. . As we have found, the content of this substance in the polymerization mixture is one of the decisive factors for the course of the anionic polymerization of 2-pyrrolidone and the quality of the polyamide-4 obtained. The method of determining the content of the components of the initiator system in the polymerization mixture for the preparation of polyamide-4 is the subject of the art. AO 219,662.

SUMMARY OF THE INVENTION The present invention provides a polymerization mixture for the preparation of polyamide-4 - consisting of a mixture of 2-pyrrolidone and 0.004 to 3.6 mmol of 2-pyrrolidone alkali salt per g of polymerization mixture containing at most 0.4 mmol of 4-aminobutanoic acid alkali salt. g of polymerization mixture, the molar ratio of the alkali salt of 2-pyrrolidone to the alkali salt of 4-aminobutanoic acid is 2 to 9.

The formation of an alkali salt of 4-aminobutanoic acid in the polymerization mixture can be prevented by appropriate selection of the base dissolution conditions in the 2-pyrrolidone. If the alkali salt of 4-aminobutanoic acid increases when the base is dissolved in the 2-pyrrolidone, the content of the active initiator-alkali salt of 2-pyrrolidone decreases, which is undesirable in view of the polymerization progress and the properties of the obtained polyamide-4 polymer.

The hydrolysis content of the resulting 4-aminobutanoic acid alkali salt increases with increasing base dissolution temperature in the 2-pyrrolidone, and for this purpose temperatures of from 25 ° C to 95 ° C need to be used with or without stirring.

Example 1

To compare the meaning of the invention, the polymer was prepared by adding 9.8 grams of 85% KOH to 220 grams of 2-pyrrolidone. Dissolution of KOH in 2-pyrrolidone was carried out at 100 ° C. 24 grams of a mixture of water and 2-pyrrolidone were distilled from the polymerization mixture by vacuum distillation under nitrogen. The polymerization mixture thus prepared contained 0.3198 mmol of potassium 2-pyrrolidone (hereinafter referred to as KPD) per gram of polymerization mixture and 0.4197 mmol of potassium 4-aminobutyric acid (hereinafter referred to as H) per gram of polymerization mixture.

The ratio of θ KPD _ The polymerization mixture was further mmol H carbonated two minutes at a flow rate of CO ₂ CO ₂ = 10 1 / min. The prepared batch was polymerized at 50 ° C. After 72 hours, a conversion of 2.31% and a cut-off viscosity number of the prepared polymer in m-cresol (at a polymer concentration in m-cresol of 0.02 g / l ([η] = 89.9 ml / g)) were achieved.

Example 2

The polymerization mixture was prepared according to the invention by the same procedure as in Example 1 except that the dissolution of KOH in 2-pyrrolidone was carried out at 50 ° C. The polymerization mixture thus prepared containing 0.5226 mmol of 2-pyrrolidone potassium salt per gram of polymerization mixture and 0.2169 mmol of 4-aminobutyric acid potassium salt per gram of polymerization mixture, i. j. -——— = 2.42, saturated 2 minutes mmol H ·

CO ₂ at a flow rate of 10 l / min. The polymerization of the prepared mixture was conducted at 50 ° C. After 72 hours a conversion of 68.7% and a polymer limit viscosity number of 555.4 ml / g were achieved. <Example 3

To 220 grams of 2-pyrrolidone was added 6.35 grams of NaOH pa. The dissolution of NaOH in 2-pyrrolidone was carried out at 40 ° C. 24 grams of a mixture of water and 2-pyrrolidone were distilled from the polymerization mixture by vacuum distillation under N ₂ . The polymerization mixture thus prepared contained 0.6710 mmol of sodium 2-pyrrolidone per gram of mixture and 0.0895 mmol of sodium 4-aminobutyric acid per gram of mixture, i.e.

Subsequently, the mixture was saturated with a mmol of H min CO ₂ at a flow rate of 10 L / min. After 72 hours of polymerization, conversion was achieved

70.8% and a viscosity limit of the obtained radius of 730 ml / g.

Claims (1)

Polymerization mixture for the preparation of polyamide-4 - consisting of a mixture of 2-pyrrolidone and 0.004 to 3.6 mmol of alkali salt of 2-pyrrolidone per Tg of polymerization mixture, characterized in that it contains not more than 0.4 mmol of alkali salt of 4-aminobutanoic acid per g % of the polymerization mixture, wherein the molar ratio of the alkali salt of the 2-pyrrolidone to the alkali; The typical salt of 4-aminobutanoic acid is 2 to 9. Printed by Moravian Printing Works,