SU477172A1 - Polymer composition - Google Patents

Description

one

The present invention relates to the field of processing of polymeric materials and can be widely used to protect polymers (polyethylene, polypropylene) from exposure to external factors such as heat, light, oxygen, air, etc., which significantly dyes the life of the polymer. Stabilized compositions based on polyolefins with the addition of thermal stabilizers or light stabilizers of polyolefins are widely known. However, such compositions do not solve the problem of the simultaneous protection of polymers from heat and light.

Polymer compositions are known on the basis of a polyolefin and a stabilizing additive, which is a mixture of 2-hydroxy-4-alkoxy-1bnzophenone with 2-ethylhexyl-bis (octylphenyl) phosphites in a 2: 1 ratio.

However, it is known that phosphites are very unstable compounds that easily undergo hydrolysis, as a result of which their stabilizing efficiency drops sharply. This process, as a rule, is accompanied by a change in the color of the polymer, which is highly undesirable with modern requirements for polymeric materials. In addition, all phosphites have a limited shelf life. Most often, phosphites are used in a mixture with phenolic antioxidants, since their individual use is insufficient to effectively protect polymers from thermo-oxidative degradation.

In order to improve the thermal and light stability of the polyolefin and to obtain unreduced polymers, a mixture of tris, (3,5-di-heated. Butyl-4-hydroxyphenyl) phosphate with 2-hydroxy, 4-K-hydroxybenzophenone, where. The ratio of phosphate and benzophenone is 1: 0.5-1: 2, the concentration of phosphate in polyolefin is 0.1 - 1 weight. %, and benzophenone 0.2-2 weight. %

The introduction of tris- (3,5-di-tert-butyl-4-o "Snphenyl) phosphate as one of the components of the stabilizing mixture allows

to provide highly effective protection of the polymer from thermo-oxidative degradation. This can be explained by the structure of a phosphite molecule, which includes elements of phenols that are difficult to access in spatial terms, preventing radical processes of destruction.

It is known that in a composition with phosphates, as well as with phosphites, the inhibition of the processes of destruction by alkylphenols is significantly accelerated.

In addition, unlike phosphites, phosphates are sufficiently resistant to hydrolysis and do not stain nolmer.

The light stabilizing efficacy of 2-4-C-hydroxy-befenone increases significantly when mixed with g / 7s- (3,5-diter. Butyl-4-hydroxyphenyl phosphate.

Example G. Powdered polypropylene of industrial brands used for the production of plastics, whose characteristics are shown in Table. 1, is mixed with stabilizers by additives in the Aeger mixer for 20 minutes at a stirrer rotation speed of 1400 rpm.

The resulting mixture granularit on a laboratory single-screw extruder ET-30 at 200-250 ° C, depending on the brand of polypropylene. Then, from the granulator, press films are thicker, a different 0.2 mm or 1 mm thick plates on an OMZ press.

Press mode:

Temperature, ° С205-230 (depending on the brand of polymer); Specific pressure,

KG / CM210.0

Warming up15

Cooling to

to 50 ° C, MIN6-8.

The samples thus obtained are tested for thermal and light aging.

Table 1

Characteristics of polypropylene used in the testing of stabilizing mixtures

Example 2. From powdered polypropylene, granulates are prepared as in example 1.

From the obtained granulator by the method of casting under pressure, plates with a thickness of 1 mm are obtained.

Mode pour

Pressure, atm150

Temperature, ° С220-250

Warm up time, s20-30

Cooling time, s30-40.

The plates prepared in this way are tested for thermo- and veto-aging.

The results of thermal and light-stabilizing efficiency of the proposed mixtures are given in table. 2 and 3.

O1

i; -f II-Comparative effectiveness of tris (3,5-di- / m / e /. boogil, -4-hydroxyphenyl) phosphate (F-50) mixed with 2-hydroxy-4-octoxybenzophenone and topanol composition KA + DLTP 2-Oxy-4-alkoxybenzophenone at

light aging at xenotest-150

Table 3

Subject invention

A polymer composition based on polyolefins and a stabilizing additive, which is a mixture of 2-hydroxy-4-alkoxybenzophenone with an organophosphorus compound, characterized in that, 3,5-di-greg. Butyl-4-hydroxyphenyl) phosphate with a ratio of the latter and benzophenone 1: 0.5 -1: 2 and the amount of stabilizing additive is 0.3-3% by weight of the polyolefin.