RU2284340C1 - Polyethylene-based composition - Google Patents

Abstract

FIELD: polymer production.

SUBSTANCE: invention provides polyethylene-based composition containing 100 wt parts low-density polyethylene, 0.5-2 wt parts stearic acid, and 4-ω-hydroxyalkyloxy-4'-formylazobenzene having general formula:

, wherein n=2, 3, 6, or 8-10.

EFFECT: increased resistance of compositions based on low-density polyethylene to light and heat ageing due to utilization of 4-ω-hydroxyalkyloxy-4'-formylazobenzene.

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Description

Introduction

The invention relates to the chemistry of polymers, in particular to the processing of polymer compositions based on thermoplastics, namely polyethylene for injection molding, moldings and film materials.

State of the art

Every year, the scope of application of polyethylene and materials based on it is expanding and the requirements for the conditions of its processing and operation are becoming more complicated. Very urgent is the task of extending the service life of materials based on polyethylene, since during processing and operation they are subjected to various influences, leading to a deterioration in their properties and ultimately to destruction.

Low-pressure polyethylene (HDPE), which is widely used for injection molding, moldings and film materials, under the influence of heat and light, becomes brittle and loses its mechanical strength. Therefore, in addition to stearic acid, light and heat stabilizers are introduced as a lubricant in a composition based on HDPE.

Known polymer composition, including, parts by weight: HDPE - 100, stearic acid - 0.5, N, N'-diphenyl-n-phenylenediamine-2 [I. Voigt. Stabilization of synthetic polymers against the effects of light and heat. L .: Chemistry, 1972]. However, the material from this composition is insufficiently resistant to light and heat and its use is limited due to the coloring of the polymer.

Also known composition [Greenspan PP, Gall RJ, J. Am. Oil. Chem. Soc., 33, 391 (1956)], consisting of the following components, parts by weight: HDPE - 100, stearic acid - 0.5 and Ionol stabilizer - 3. Although this polymer composition is physiologically harmless, it is not very resistant to light, because Ionol stabilizer does not show light stabilizing properties.

Also known is a polymer composition of the following composition, parts by weight: HDPE - 100, stearic acid - 0.5, carbon black - 3 [Chemicals for polymeric materials. Ed. B.N. Gorbunova. - M .: Chemistry, 1984, p.127]. However, the material from this composition is not sufficiently resistant to light and heat and can only be used for black products.

Also known is a polymer composition that is closest in essence to the invention, of the following composition, parts by weight: HDPE - 100, stearic acid - 0.5, Benazol P - 0.1 [Chemicals for polymeric materials. Ed. B.N. Gorbunova. - M .: Chemistry, 1984, 127 pp.]. However, the material from this composition is not sufficiently resistant to light and heat.

SUMMARY OF THE INVENTION

An inventive task is to find a polymeric composition based on HDPE, including HDPE, stearic acid as a lubricant and stabilizer, which would increase the resistance of the material to light and heat.

The problem is solved by a polymer composition based on polyethylene, including HDPE, stearic acid as a lubricant and a stabilizer, which contains 4-ω-hydroxyalkyloxy-4'-formylazobenzene of the general formula as a stabilizer

where n = 2, 3, 6, 8-10,

at the following content of components, parts by weight:

HDPE one hundred stearic acid 0.5-2 4-ω-hydroxyalkyloxy-4'-formylazobenzene 0.1-0.5

The material of the claimed polymer composition has a higher resistance to the action of both light and heat at the same time.

Information confirming the reproducibility of the invention

The following substances are used to prepare the composition:

1. HDPE GOST 16338-85

2. Stearic acid GOST 6484-64

3. Benazol P TU 6-14-197-76

4. 4-ω-hydroxyalkyloxy-4'-formylazobenzene obtained by boiling 4-hydroxy-4'-formylazobenzene and n-chloroalcohols in dimethylformamide in the presence of potash [S.A. Kuvshinova, A.V. Zavyalov, O.I. Koifman , V.V.Aleksandriysky, V.A. Burmistrov. Mesogenic 4-ω-hydroxyalkyloxy-4'-formylazobenzenes. ZhOKh, 2004, v.40, v.8, p. 1161-1164].

The preparation of the polymer composition, light thermal aging and testing of the material from this composition is illustrated by the following example.

Example 1. Mixing in accordance with the formulation of low-pressure polyethylene, stearic acid as a lubricant and the stabilizer 4-ω-hydroxyalkyloxy-4'-formylazobenzene. This polymer composition was loaded onto rollers heated to a temperature of 160 ° C, rolled to obtain a fabric that was uniform in structure and color, from which, after being removed from the rollers, the plates were pressed on a laboratory press at 140 ° C and a pressure of 5 MPa for 2 minutes, followed by cooling in press. Samples of a thickness of 0.6 ± 0.05 mm were obtained. In the process of producing HDPE films, rolling and subsequent calibration under pressure, aging and testing of samples, no exudation and volatility of stabilizers were detected.

These samples were placed under a DRT-375 lamp with a power of 375 W over a distance of 20 cm. Heat and light aging was carried out at 70 ° C for 72 hours according to GOST 8979-85.

100 × 10 mm samples were cut from the initial (before aging) and aged polymer films. Standard samples were clamped in the clamps of a tensile testing machine РМ-30-1 and the load was determined at which the sample F _i breaks and the length of the working section of the sample, measured at the time of its break Δl _i , is increased according to GOST 14236-86.

Tensile strength (tensile stress) was calculated by the formula

, где F_i - разрывная нагрузка, A_i - сечение образца.

where F _i - breaking load, A _i - section of the sample.

The average of 30 results was determined.

The relative elongation (ε _p ,%) at break was determined by the formula

,

,

where l _i is the initial size of the i-th sample.

The average of 30 results was determined.

Resistance to light thermal aging was determined as the percentage of preservation of the property (σ and ε _p ) after light thermal aging.

Comparison samples from a polymer composition consisting of HDPE, stearic acid as a lubricant and Benazole P as a stabilizer were prepared and tested according to the same GOST 8979-85 as for samples from the claimed polymer composition.

Table 1 shows the compositions of the compositions based on HDPE.

Table 2 shows the test results of the samples for light and heat resistance.

The data of table 2 clearly confirm that the use of the claimed composition based on polyethylene allows 1.3-1.4 times to increase the strength characteristics of the polymer material from this composition and 3-4 times to increase its elasticity.

Table 1
Formulations of polyethylene compositions N p / p Name of ingredients The content of ingredients, parts by weight one 2 3 four 5 one HDPE one hundred one hundred one hundred one hundred one hundred 2 Stearic acid 0.5 0.5 1,0 1,5 2.0 3 Benazole P 0.1 - - - - four A-2 - 0.1 - - - 5 A-3 - - 0.3 - - 6 A-6 - - - 0.4 - 7 A-8 - - - - 0.5 Note: A-2, A-3, A-6, A-8 - 4-ω-hydroxyalkyloxy-4'-formylazobenzene of the general formula

where for A-2, A-3, A-6, A-8 n = 2, 3, 6, 8, respectively.

table 2
Sample Test Results The name of indicators Recipe Number one 2 3 four 5 1. Destructive stress, MPa - under normal conditions 28.60 29.80 28.90 29.36 30.15 - after light thermal aging 23.90 34.51 33.58 34,20 34.83 Resistance to aging,% 83.60 115.8 116.20 116.50 115.50 2. The relative elongation at break,% - under normal conditions 19 eighteen fifteen 17 fifteen - after light thermal aging 12 37 thirty 40 35 Resistance to aging,% 63,2 205.5 200,0 235.3 233.8

Claims (1)

Composition based on polyethylene, including low-pressure polyethylene, stearic acid as a lubricant and stabilizer, characterized in that it contains 4-ω-hydroxyalkyloxy-4'-formylazobenzene of the general formula as stabilizer

where n = 2, 3, 6, 8-10, in an amount of 0.1-0.5 parts by weight per 100 parts by weight polyethylene in the following ratio, wt.h .: Low-pressure polyethylene one hundred Stearic acid 0.5-2 4-ω-hydroxyalkyloxy-4'-formylazobenzene 0.1-0.5