SU376413A1 - METHOD OF OBTAINING STABILIZED POLYAMIDES - Google Patents

Description

The invention relates to methods for producing polyamides stabilized to thermal oxidative degradation. Thermo-oxidative degradation inhibitors are used to stabilize polyamides, which are introduced either into the finished polymers or into the monomers before polymerization. As inhibitors, aromatic amines, aromatic oxo compounds, phosphorus compounds, copper salts and a number of other organic and mineral substances are used. In order to increase the effectiveness of the stabilization of the polyamides according to the invention, it has been proposed to use a titanium oxide disalicylate (DOT) of the formula in an amount of 0.5-5 wt. % This inhibitor is not inferior in efficiency to di-r-naphthyl-phenylenediamine (DNFDA) and a mixture of copper acetate and potassium iodide-inhibitors, which have received lromo-blind use. Compared to DNFDA, titanium oxide disalipilate has the advantage that polyamides with the addition of this inhibitor do not stain during Processing and long-term storage in air. Example 1. DOT in an amount of 0.5% by weight of polyamide in the form of an acetone solution is mixed with powdered polyamide obtained by polycondensation of adipic acid 1,6-hexamethylenediamine salt of adipic acid, and acetone is evaporated. The degree of thermo-oxidation is determined by the Absorption of oxygen as a result of heating the polymer at 200 ° C in an oxygen atmosphere at an initial pressure of 200 lHHg. Art. By maintaining the stabilized sample at 200 ° C for 2 hours, the initial oxygen pressure is reduced by 11 lsh. The pressure reduction in the case of thermal decomposition of unstabilized polyamide and polyamide stabilized with DNFDA (0.5%) is 67 and 12 mm, respectively. Example 2. A mixture of 100 weight. h. e-zaprolaktam, 0.3 wt. including 1,6-hexamethylenediamine salt adipic acid and 0.5 weight. The DOT is first heated in a glass vial filled with argon at 220 ° C for 2 hours, then at 260 ° C in a stream of argon for 6 hours. The resulting polymer is pulverized and oxidized under the conditions of Example 1. As a result of thermal oxidation for 1 hour, the pressure drop is 7 mm Hg. Art. The pressure drop as a result of the thermal oxidation of samples of unstabilized poly-e-caproamide and poly-e-caproamide chips with the addition of 0.5% of DNFDA prepared in the same way is 25 and 6 jl, respectively.

Example 3. DOT in the amount of 0.5 weight. % is introduced into the p-broshx-like poly-E-caproamide. The decrease in pressure during the oxidation of such a sample at 170 ° C and an initial oxygen pressure of 200 mm Hg. Art. and a heating time of 2 hours is 3 mm. For unstabilized noli-e-caproamide and poly-e-caproamide stabilized with a mixture of copper acetate (0.25%) with potassium iodide (0.25%), the pressure decrease is respectively 19 and 3 mm.

Example 4. A mixture of 100 weight. h. y-dodecalactam, 5 wt. including water, 0.2 wt. including orthophosphoric acid and 0.5 wt. Part DOT is heated first under pressure at 280 ° C for 8 hours and

376413

then in a current of inert gas at the same temperature for 6 hours.

Decrease in pressure 1 during the oxidation of polyamide at 170 ° C for 2 hours with an initial oxygen pressure of 200 mm Hg. Art. is 6 mm. For the unstabilized polymer, in the control one, the pressure reduction is 20 mm.

Subject invention

The method of obtaining stabilized polyamides by introducing thermo-oxidative degradation inhibitors, characterized in that, in order to increase the effectiveness of stabilization, titanium oxide disalicylate is used as an inhibitor in an amount of 0.5 to 5 wt. %