DD154708A1 - STABILIZER COMBINATION FOR EXTRUDABLE IMPACT POLYVINYL CHLORIDE - Google Patents

Abstract

The invention relates to a stabilizer combination for extrudable impact-modified polyvinyl chloride, which contains as Schlagzaehkomponente preferably ethylene vinyl acetate. The object of the invention is to improve the previously known stabilizer systems for the stabilization of extrudable impact polyvinyl chloride so that a trouble-free processing on conical short twin screw extruders is possible, and thin-walled tubes and profiles are obtained with high mechanical characteristics, their aging behavior improves and the shear stress The object is achieved by dissolving a mixture of barium-cadmium compound having a barium content of 3.5 to 8% by weight and a cadmium content of 2 to 12% by weight and a basic lead acetate. Lead phosphide mixture are used with a lead content of 40 to 93 wt .-%. The stabilizers are present in the polyvinyl chloride mixture between 0.5 to 5%.

Description

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Title of the invention

Stabilizer combination for extrudable impact-resistant polyvinyl chloride

Field of application of the invention

The invention relates to a stabilizer combination for extrudable impact-resistant polyvinyl chloride, which preferably contains ethylene vinyl acetate as an impact-modifying component. The stabilized impact-resistant polyvinyl chloride is particularly suitable for. Extrusion of thin-walled tubes and half-round profiles on conical short double screw systems ♦

Characteristic of the known technical solutions

Various stabilizer systems are known for stabilizing impact-resistant polyvinyl chloride.

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Thus, the use of barium-cadmium complex stabilizers for components made of impact-resistant polyvinyl chloride-S with different impact-resistant components, such as ethylenevinylacetate or chlorinated polyethylene, recommended by stabilizer manufacturers and commodity producers (stabilizer manual from Siegle & Co., Stuttgart, stabilizers for PVC, 1970).

The stabilization effect achieved by the barium-cadmium compounds is, according to Menzel (Angew · Makromol · Chemie, 47 (1975), pp. 181 to 199 and pp. 201 to 216), the good dispersibility in polyvinyl chloride and by the synergistic effect of the complex compounds · They are liquid throughout the processing range and show quite good processing behavior.

However, it is known in the art that the processing of barium-cadmium complex-stabilized impact-resistant polyvinyl chloride S with ethylene vinyl acetate impact modifier on conical twin screw extruders is associated with thin walled profiles, especially pipe profiles, with the following disadvantages

- Increased load on the extruder drive

- high shear stress of impact-resistant POlyvinylchlorid-S

- significant reduction of emissions

- Complicated shaping and increased dimensional tolerances by adversely reducing the melt viscosity of the plastic material.

Furthermore, the stabilization of polyvinyl chloride with lead compounds is known.

The use of lead stabilizers on the basis of lead stearates and lead phosphites requires

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Fleischer (Kunststoffe 67 (1977), 6, pp 312-316, an increase of the cylinder temperature of the extruder by approximately 30 · ⁰ C, since the stabilized with polyvinyl lead compounds a completely different extrusion behavior is shown as having Barium.Cadmium compounds stabilized polyvinyl chloride.

Another specialty of lead stabilization is that in the semi-finished products of the thus stabilized impact resistant polyvinyl chloride a very rapid drop in the mechanical characteristics after a brief W impact, z. B. the impact resistance and the impact strength, ready at 500 hours Xenotest weathering occurs, so that such semi-finished products can not be used for outdoor use ·

Another disadvantage is the discoloration or chalking in these semifinished products (Menzel, Angew Makromol Chemistry 47 (1975), pp. 181 to 199).

Object of the invention

The aim of the invention is to improve the previously known stabilizer systems for the stabilization of extrudable impact-resistant polyvinyl chloride so that a trouble-free processing of the stabilizer-containing polyvinyl chloride mixtures on conical Kurzdoppelschneckenextrudern is possible and thin-walled profiles are obtained with high mechanical characteristics whose aging behavior meets the requirements of Outdoor use correspond and an extension of the scope of application in terms of use at high altitudes and processing at low temperatures allows. A further object of the invention is to reduce the load on the extruder drive in comparison to barium-cadmium stabilization, to increase the shear stress of the impact-resistant polyvinyl chloride and the output of the system.

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Explanation of the essence of the invention

- The technical problem of inventions

The object of the present invention is to develop a stabilizer combination for extrudable impact-resistant polyvinyl chloride with ethylene vinyl acetate as an impact component which is suitable for economical processing on short-conical conical extruders and satisfies the above requirements.

Explain the nature of the invention

The technical object is achieved by a mixture of the known stabilizers A and B, wherein A is a barium-Oadmium-Verbfcadung with a barium content of 3.5 to 8 wt .- $ and a cadmium content of 2 to 12 wt .- $ and B is a lead acid lead-lead phosphite with a lead oxide content of 40-93% by weight.

The stabilizers A and B are present in the mixture in a total amount of 0.5 to 5 $.

As stabilizers A and B, all commercially available stabilizers can be used in the range of the specified metal compounds in the mixture according to the invention.

Preferably, the following compounds are suitable:

- lead stearate

- lead phosphine

- Barium-cadmium complex

The stabilizer combination according to the invention is added to the polyvinyl chloride in proportions of from 2 to 5% by weight

Compound with customary additives, such as lubricants and pigments.

The polyvinyl chloride S to be stabilized preferably has a K value of 59 to 70 and a mass fraction of the impact strength component of 0.5 and 5 $.

Polyvinyl chloride is mixed together with the stabilizer combination and the customary additives in known heating and cooling mixers to form a dry blend and processed to thin-walled profiles on a conical twin-screw extruder.

When using the stabilizer combination according to the invention, the dry blend mixture is extruded at temperatures of 423 to 473 K into thin-walled profiles and calibrated, cooled and cut to length in known devices.

The advantage of the stabilizer combination is that it is possible to process the impact-resistant polyvinyl-S mixture on a conical short twin-screw extruder with surprisingly high throughput at low load of .Antriebssystems to thin-walled profiles. It is surprising that the mechanical values are improved and their long-term behavior does not drop significantly as expected, due to aging processes, as occurs with lead stabilizations. Furthermore, surprisingly good mechanical properties result at temperatures up to 248 K, which are processed at low temperatures enable and extend the scope of application ·

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embodiment

Extruded gutter ITG 130 on an extruder

recipe

Polyvinyl chloride S 60 100 parts 100 parts 100 parts mm Impact resistant component 10 parts 10 parts. 10 parts i Stabilizer content Pb-based 3.7 parts • j 9 parts kJ / m ² St ab ilisat orgehalt Ba / od basis - 3.2 parts 1 * 9 parts 20 years lubricant content 0.8 parts 3.4 parts 3, 4 parts dyes 1.5 parts 3.4 parts 3 parts Parameter: throughput 81.4 kg / h 63.5 kg / h 73 kg / h Extruder temperature 423 to 473 K. Extruder loading 10 to .14 A 20 to 28 A 12 to 16 A Properties: Fall breakage 248 K TGL 25 129 500 mm 1000 mm 1000 Impact resistance 273 K TGL 25 129 (without break) $ 40 loo ψ 100 Impact resistance after 4000 hours Xenotest (293 K) 5 kJ / m ² > 3O kJ / m ² > 30 lifespan 8 years 20 years

Claims (1)

Erf charge response Stabilizer combination for extrudable impact-resistant polyvinyl chloride with ethylene vinyl acetate as Schlagzähkomponente, characterized in that the stabilizer combination consists of a mixture of the known stabilizers A and B, wherein A is a barium-cadmium compound with a barium content of 3j5 to 8 wt .- ^ and a cadmium content of 2 to; 12% by weight and B is a basic lead acetate-lead phosphite mixture with
a lead oxide content of 40 to 93 wt .- ^ and the stabilizers A and B are present in the mixture in a total amount of 0.5 to 5 $> .