DD283503A7 - STABILIZER FOR POLYVINYL CHLORIDE AND A PROCESS FOR ITS PRODUCTION - Google Patents

Abstract

The invention relates to a stabilizer for polyvinyl chloride and a process for its preparation. For the proposed stabilizer of the polyvinyl chloride, a micronized hydrophobized alkali nitrate is used. The process for its preparation consists of the following: The alkali metal nitrate is micronised (preferably with sizes less than 50 micromols, independently or together with a hydrophobizing agent.) As hydrophobing agents, components participating in the polyvinyl chloride compositions are used - lubricants or stabilizers in amounts of 1.01: Micronization is accomplished in known apparatus such as spherical, hammer, vortex, colloidal and micronizers, etc. In the independent micronization of the alkali nitrate, hydrophobicization in mixing apparatus is carried out under intensive stirring The stabilizer proposed has a good compatibility with the components of the polyvinyl chloride compositions, according to the lyophilic property obtained when the alkali nitrate is treated with the hydrophobizing agent Spers with a stable disperse stability and also easily accessible. {stabilizer; for polyvinyl chloride; Production method; Alkali metal nitrate; micronized; hydrophobic}

Description

- 1 - Berlin, December 5, 1989 69 328/12 SchAA

Stabilizer for polyvinyl chloride and a process for its preparation

Field of application of the invention

The invention relates to a stabilizer for polyvinyl chloride and a process for its preparation.

Chara k teristik of the known state of the art

Stabilizers of polyvinyl chloride (1) are known, of which the most commonly used are: lead salts, barium-cadmium and calcium-zinc complexes, organotin and organo-antimony compounds (2). The disadvantages of these stabilizers are: the toxicity of the lead and barium-cadmium complexes, the inadequate effectiveness of the potassium-zinc compositions, difficult to access and / or with an unpleasant odor as far as the organic tin and antimony compounds are concerned.

Alkali nitrates are also known as stabilizers of polyvinyl chloride, but have no practical application, due to some deficiency of these salts, such as hydrophilicity, precipitability in powder form, incompatibility and appreciable dispersibility of the components of the polyvinyl chloride compositions.

Object of the invention

The invention provides a stabilizer,

which is finely disperse, has consistent disperse stability, and is readily accessible. Furthermore, a simple method of making the stabilizer is provided.

Explanation of the essence of the invention

It was an object of the present invention to provide a stabilizer of polyvinyl chloride having hydrophobic behavior, forming stable finely dispersed forms, having sufficient compatibility with the components of polyvinyl chloride compositions well dispersed therein, and a process for its production of readily available ones raw materials.

This object has been achieved by using a micronized hydrophobized alkali nitrate for the stabilizer of the polyvinyl chloride. The process for its preparation consists in the following: the alkali nitrate is micronised (preferably with sizes below 50 micromoles) independently or, what is preferable, together with a hydrophobizing agent. As hydrophobing agents, components commonly used in the polyvinyl chloride compositions are used - lubricants or stabilizers in amounts to the alkali metal nitrate of 0.01: 1 to 0.9 j 1. The micronization is in known apparatus such as ball, hammer, vortex , Koloidal u. s. Micronizers completed. In the self-micronization of the alkali nitrate, hydrophobing is carried out in mixing apparatus with intensive stirring of the nitrate to be micronized with a hydrophobizing agent.

The advantages of the invention are that a stabilizer is proposed which is compatible with the components of the polyvinyl chloride compositions, according to the lyophilic property obtained when the alkali nitrate is treated with the hydrophobizing agent. The stabilizer is finely dispersed, with a stable disperse stability and also easily accessible.

The advantages of the method consist in that are used as hydrophobizing agents conventional components of the polyvinyl chloride compositions, that it is simple and is implemented in a generally accessible apparatus. Another advantage of the process is that the hydrophobing is accomplished simultaneously with the micronization of the alkali nitrate, with the possibility of successive micronization and hydrophobing not being excluded.

embodiments

Based on the examples given below, the invention is explained in more detail, without thereby limiting.

example 1

Into a mixer is added 10 kg of sodium nitrate having an average size of crystals of 1 mm, 1 kg of powdery calcium stearate. The mixture is stirred for 5 minutes at 1200 rpm. The resulting mixture is micronized at a peripheral speed of the rotor of 100 m / sec and at a continuous feed of 5 kg / hr. The product obtained has

- 4 - ZfS50b

an average size of 40 micromols. This product floats in water and its sieve composition does not change after 3000 hours of storage.

Example 2 (comparative example )

The sodium nitrate rr ¹ : is micronized at the same ratios as in Example 1 without first being mixed with calcium stearate. The feeding of the micronizer is uneven, wegon the poor flowability of the nitrate. The micronized product has the same average size * as in Example 1, but it quickly loses its flowability and after 28 hours it forms permanent agglomerates. The product sinks in the water and dissolves.

Example 3

To a mixture of 40 g of stearic acid and 70 g of polyethylene wax, 120 g of product prepared according to Example 1 is added at a temperature of 120 ⁰ C. The mixture is stirred intensively for 5 minutes. It is produced a homogeneous mass, which hardens after cooling.

Example 4 (Comparative Example )

In the proportions of Example 3, instead of 120 g of product prepared as in Example 1, 120 g of product prepared as in Example 2 are added after 48 hours of storage. A non-homogeneous mass is obtained in which agglomerates of non-dispersed alkaline nitrate are present. Agglomerates are also observed after stirring for 40 minutes.

Example 5

In the ratios of Example 4, sodium nitrate "made according to Example 2" is used, but immediately after micronization. To obtain a homogeneous mixture, it must be stirred for 30 minutes.

Example 6

Using a product prepared as in Example 1, a polyvinyl chloride composition is prepared. In a mixer 10 kg of polyvinyl chloride suspension with ¹ ^ ST ⁼ ^ ® * ^ 9 stearic acid, 70 g of polyethylene wax, 20 g of titanium dioxide, 100 g of chalk and 120 g of product prepared according to Example 1, dosed. The mixture is stirred at 1200 revolutions / minute, during which it is heated to a temperature of 130 ^° C. for 7 minutes and then cooled down to 40 ^° C. The composition produced has the following properties: bulk material - 570 g / l ( ISO-R60), free-flowing - 23 ml / sec. (DIN 53492), thermal stability in oven - 80 minutes (ASTM 2115-67).

Example 7

In the proportions of Example 6, a composition is prepared by replacing the amounts (quanta) of stabilizer and lubricants with 230 g of product prepared according to Example 3. The prepared composition has the properties of the composition prepared according to Example 6.

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Example 8 (Comparative Example )

In the proportions of Example 6, a composition is prepared in which the quantity of stabilizer and lubricants is replaced by 250 g of a mixture of calcium-zinc compositions and a lead stabilizer. The composition prepared has the properties of the composition prepared in Example 6, but its thermal stability is 60 minutes.

Claims (2)

in claims 1. A stabilizer for polyvinyl chloride, characterized in that it is a hydrophobized micronized alkali metal nitrate. 2. A process for the preparation of the stabilizer according to the invention, characterized in that the alkali metal nitrate is micronized in the presence of lubricants and / or stabilizers for polyvinyl chloride in a quantum of from 0.01: 1 to 0.9: 1 over the alkali nitrate.