CS243904B1 - Polypropylene degradation activator - Google Patents

Abstract

Mixtures of powdered or granular isotactic polypropylene with bis(o-benzamidophenyl)disulfide were degraded under static conditions in the chamber of a VP-05 extrusion plastometer. By selecting the sample processing temperature in the range of 255 to 300 °C, the concentration of bis(o-benzamidophenyl)disulfide from 0.02 to 1% by weight and the duration of thermal stress from 1 to 30 minutes, the desired melt flow index value can be achieved. Bis(o-benzamidophenyl)disulfide can be used as a degradation activator even in the presence of a stabilization system.

Description

The invention relates to the use of bis(o-benzamidophenyl) disulfide as an alcohol activator for the degradation of polypropylene for the purpose of modifying its molecular characteristics.

Commercial types of polypropylene intended for the production of fibers and injection molded products do not meet the requirements of processors in terms of molecular characteristics.

Depending on the type of product, polypropylenes with melt flow index values of up to 50 g/10 minutes are required, while the types of polypropylene produced in our company have melt flow index values of up to 11 g/10 minutes.

There are two possible ways of modifying the molecular characteristics; during the synthesis of the polymer by appropriate adjustment of the polymerization system, or by additional modification of the finished polymer during the processing process using a degradation activator. This method simultaneously allows a significant narrowing of the molecular weight distribution.

Currently, the second method is used to modify the processing properties of polypropylene, using low-molecular substances such as organic and inorganic peroxides, nitrogen compounds, sulfur compounds and C-C initiators as degradation activators.

The need for polypropylene with modified molecular characteristics has so far been met by importing finished modified polymer or by importing degradation activators from abroad.

The above-mentioned shortcomings are eliminated by the subject of the invention, the essence of which is the use of bis(o-benzamidophenyl) disulfide of domestic production as an activator of the degradation of powdered polypropylene, or powdered or granular stabilized polypropylene. The degradation of mixtures of polypropylene with bis(o-benzamidophenyl) disulfide from the initial melt flow index value of the type of polypropylene used to the melt flow index value of 250 g/10 minutes is carried out in a processing device in the temperature range of 255 to 300 °C, at a bis(o-benzamidophenyl) disulfide concentration of 0.02 to 1% by weight.

Until now, bis(o-benzamidophenyl) disulfide has been used as a plasticizer in rubber processing.

Example 1

Mixtures of polypropylene powder with bis(o-benzamidiophenyl)disulfide were processed in the chamber of the VP-05 extrusion plastometer under static conditions as follows: The sample was poured into the melting chamber of the plasticizing cylinder at the selected temperature and closed with a piston. The nozzle was plugged with a wire. After the selected retention time, the sample was extruded in the form of a string, which was granulated and the melt flow index of the granules was measured under standard conditions (ČSN 64 0861).

The test results are shown in Table 1. The raw polypropylene powder had a melt flow index of 3.42 g/10 minutes. The results for samples containing no degradant are also shown for comparison.

Table 1

Processing temperature: 260 °C concentration of bis (o-benzamidophenyl) disulfide, % by weight retention time, minutes melt flow index, g/10 minutes

2.61

12.78

5 14.90

16.50

3.51

7.46

0.07 5 11.52

20.27

3.66

8.04

0.18 5 15.33

22.45

3.76

8.71

0.35 5 17.22

25.48

Example 2

Mixtures of polypropylene powder with bis(o-benzamidophenyl) disulfide containing a constant amount of the phenolic antioxidant 2,6-di-tert-butyl-4-methylphenol ^of 0.1% by weight were processed in the same way as described in Example 1.

The results for temperatures of 260 and 270 °C and different degradant concentrations and thermal stress lengths are presented in Table 2.

Table 2 temperature, °C retention time, melt flow index, g/10 minutes minutes at the concentration of bis (o-benzamidophenyl) disulfide % by weight

0.04 0.07 0.21 0.35 0.56 0 6 11.12 14.82 15.63 16.16 16.32 6.33 260 10 15.13 25.55 26.63 30.08 33.59 6.88 6 21.90 32.49 41.19 44.90 41.74 — 270 10 27.88 59.33 100.02 128.66 149.64 —

Example 3 Mixtures of commercially stabilized granular plastomer with the trade name Mosten 55 212 and a melt flow index of 0.6 g/10 minutes were degraded in a compression chamber at 260 and 280 °C by the process described in Example 1. The resulting melt flow index values are given in Table 3.

Table 3 Melt flow index Thermal stress length, g/10 minutes minutes for degraded samples

at temperature 0 3 5 7 10 15 260°C 0.86 1.40 2.17 3.45 5.66 10.21 280°C 0.86 2.40 9.39 22.40 80.54 immeasurable Can be used like this edited polypropylene is in fiber and coats-

the car industry.

Claims (3)

EYE OF THE INVENTION Use of bis (o-benzamidophenyl) disulfide as activator of polypropylene degradation.