DE1770817A1 - Process for the production of polyvinyl chloride - Google Patents

Description

CHEMISCHE WERKE HÜLS AG 4370 Mari, July 5th, 1968

- Patent Department - 2067 / J

Our reference: O.Z. 2297 Process for the production of polyvinyl chloride

In addition to the block and LösungsmittelpOlynierisation of vinyl chloride etc. The suspension and emulsion polymerization are now playing the much larger role * The two latter are carried out in aqueous phase.

In suspension polymerization, the activator is in the vinyl chloride The suspension of vinyl chloride or polyvinyl chloride is dissolved in water for the duration of the polymerization stabilized with a suspension aid, i.e. the polymerization runs off in the droplet suspended in water.

In the case of emulsion polymerization, on the other hand, a water-soluble one becomes Activator used. As a result, the polymerization takes place at the water / vinyl chloride interface. f

As is known, vinyl chloride can be added to ■ without further additives polymerize in this way, but the conversion is low, and no dispersions are obtained.

When adding emulsifiers, e.g. fatty acid salts or synthetic ones Detergents, you get higher sales and stable Dispersions. .

The amount of emulsifier to be used depends primarily Line according to the polymerization technique and also fluctuates a little

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with the type of emulsifier.

Since, for reasons of economy, the aim is always to work with high-percentage * namely at least 40%, mostly 45 to 47% solutions, the Emuigator concentration should not be below 1.5 % for continuous operation and not below 1.5% for discontinuous operation Reduce O> 5 % .

For the subsequent work-up to the powder, the Dispersions subject to mechanical stress, such as pumps. Therefore, they must be stable over long periods of time be.

As a result, the emulsifier concentrations used are ■ tions are practically still considerably above the specified amounts.

These comparatively high emulsifier concentrates have a very detrimental effect on the end products. You effect namely a reduced transparency and an increased water sensitivity of the polymers. These disadvantages make themselves felt particularly noticeable since spray drying has been the main work-up process for emulsion polyvinyl chloride has prevailed.

Naturally, the existing ones remain in this work-up process Accompanying substances retained in the end product. However, also with the less common precipitation as a work-up process so large amounts of emulsifiers still remain in the end product that they are in the above-described form Way noticeably as significantly annoying.

It has now surprisingly been found that these disadvantages of the prior art can be avoided if you are involved in the polymerization of vinyl chloride in aqueous emulsion Use of customary emulsifiers in the presence of 0.1 to 1.0

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-> ■ - ■ OZ 2297

5.7. I968

Percentage by weight, in particular 0.1 to 0.5 percent by weight, based on the monomer used, of two alcohols works, one of which contains k to 8 carbon atoms and the other 10 to 20 carbon atoms and whose weight ratio to one another is between 1:10 and 1: 1.

The alcohols containing 4 to 8 carbon atoms are in Limited solubility in water. Can be used as such for example n-butanol, sec-butanol, iso-butanol, n-pentanol, n-hexanol, iso-hexanol.

The alcohols containing 10 to 20 carbon atoms are in. Practically insoluble in water. It can be used as such n-lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol.

The two alcohols should be used together in amounts of 0.1 to 1.0 Percent by weight, preferably 0.1 to 0.5 percent by weight, can be used. Their proportions by weight should be 10: 1, preferably 1: 1 (alcohol with limited water solubility: water-insoluble alcohol).

■■■■■ '. ■ ^:

The emulsifiers used in emulsion polymerization technology are intended to be used customary surface-active substances, such as alkyl sulfonates, alkyl sulfates, alkyl aryl sulfonates and fatty acid salts, are used as described, for example, in the monograph "Polyvinyl Chloride and vinyl chloride copolymers "from Helmut Kainer, Springer-Verlag, Berlin, Heidelberg, New York, 1965 * page 36ff are described.

The catalysts used are the substances customary in emulsion polymerization technology, such as potassium persulfate, H ₃ O ₃ / potassium persulfate, bisulfite / potassium persulfate or ascorbic acid / potassium persulfate. .

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If an emulsion polymerization is carried out according to the invention through, so you can work discontinuously with emulsifier contents of less than 0.5 percent by weight - down to * 0.1 percent by weight - stable polyvinyl chloride emulsions with solids contents of more than 40 percent by weight are obtained. Even when working up by the spray drying that is customary today, in which the during the polymerization before * existing accompanying substances in the end product inevitably remain completely intact ', products are created which are characterized by high transparency and low water sensitivity due to the low emulsifier content *

The two alcohols required for polymerization escape during spray drying according to their water vapor moisture content so that only a small amount of emulsifier remains in the end product.

example 1

In §in§ffl d? Uekf§§t§n Rühfkegeel from ko 1 content wsfdin presented:

14 kg deionized water 10 g K ₂ S ₂ O ₈

1 g NaHSO (or other redox components) 25 g n-butanol
25 g of n-lauryl alcohol
20 g sulfosuccinic acid di-iso-octyiester

The pH of this solution is 6.5 and the surface tension is approx. 29 dynes / cm. After flushing of the gas space with _N2 To this solution, 10 kg of liquid vinyl chloride placed under pressure and heated to 50 ⁰ C and held at this temperature.

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5.7.1968

After the initial pressure has fallen from approx. 5 * 5 atmospheres to 2 atmospheres, the mixture is cooled to room temperature and the unreacted monomer is depressurized. A stable polyvinyl chloride dispersion is obtained which contains practically no coagulate. The final pH is 3.2, the surface tension about 70 dynes / cm. The dispersion has a solids content of 42.8 %,

Example 2 .

Is used in the approach in Example 1 instead of sulfosuccinic acid ester the same amount of alkyl sulfonate of the K 50 type, the dispersion obtained has the same properties like the one in example 1.

^x ^ (mean chain length 15 to 16 carbon atoms)

example 3

One operates as in Example 1, instead of 25 g of n-butanol t, however, 25 g i-amyl alcohol and 25 g of myristyl alcohol used in place of 25 g of lauryl alcohol. The dispersion has a solids content of 4.0 percent by weight. ■

Example 4

The procedure is as in Example 2, but instead of 25 g n-butanol and 25 g laury alcohol are used: 25 g n-hexanol and 25 g stearyl alcohol * The dispersion has a solids content of 42.5 percent by weight.

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Claims (1)

- 6 - OZ 2297 5.7.1968 Claim Process for the production of polymers of vinyl chloride by polymerizing vinyl chloride in an aqueous emulsion using conventional emulsifiers, characterized, that in the presence of 0.1 to 1 percent by weight, in particular 0.1 to 0.5 percent by weight, based on the used Monomer, two alcohols works, one of which has 4 to 8 carbon atoms and the other 10 to 20 carbon atoms and their weight ratio to one another is between 1:10 and 1: 1. 109883/1380