DD256136A1 - PROCESS FOR PREPARING POLYMERS OF VINYL CHLORIDE - Google Patents

Abstract

The invention relates to a process for the preparation of polyvinyl chloride having different porosity and relatively high Schuettdichten. The process is designed using polysiloxane-polyoxyalkylene block copolymers as suspension stabilizers, and by carrying out the polymerization in two stages, the first stage being limited to a conversion of up to 20% and at a temperature which varies according to the desired K value above or below the temperature corresponding to the K value.

Description

Field of application of the invention

The invention relates to a process for the preparation of polymers of vinyl chloride by radical polymerization of vinyl chloride and predominantly vinyl chloride-containing monomer mixtures by the suspension process.

Characteristic of the known technical solutions

The suspension polymerization of vinyl chloride or the preparation of copolymers based on vinyl chloride is carried out on an industrial scale in the presence of dispersants for the preparation and stabilization of the vinyl chloride / polyvinyl chloride suspension in the aqueous phase. It determines u.a. the property of the dispersant system the distribution of the monomer in the aqueous phase, the morphology of the PVC Koms, in particular its porosity, the particle size distribution, but also the thermostability of the polymer. For the processing of the polyvinyl chloride, particularly the bulk density and the plasticizer capacity are of crucial importance. However, both properties are related in such a way that usually in the improvement of one size deterioration of the other occurs.

As dispersants u.a. Cellulose ethers, as described in DE-OS 2412014, in question. Furthermore, cellulose ethers in a mixture with partially saponified polyvinyl acetate (DD-PS 145539) or only polyvinyl acetate (DE-AS 1142238) are optionally used in conjunction with nonionic emulsifiers (DE-OS 2945073). To achieve high porosities, additional aliphatic or aromatic hydrocarbons or alcohols are used (US Pat. No. 2875186, US Pat.

Furthermore, it is known, by adding long-chain fatty acids or their esters or by adding ionic or nonionic surfactants, often combined with other additives, such as reducing agent to the polymerization to increase the plasticizer receptivity (DE-OS 2365134,2151703, DE-PS 1 545 179, DE-OS 2244905.2143604).

Also described is the combination of suspension stabilizers for influencing the plasticizer receptivity (US Pat. No. 3,879,365, DE-AS 1720328, DE-OS 2209592).

A polyvinyl chloride having a high bulk density, low porosity and a relatively broad particle size distribution is obtained when using styrene / maleic anhydride copolymers as a dispersant (DD-PS 13583.14358).

Furthermore, a polyvinyl chloride with a relatively high bulk density and a good porosity by addition of diallyl or triallyl compounds to the commonly used dispersants or their mixtures (DD-PS 151455).

The known methods have the disadvantage that they affect only one size positively and the others are neglected, d. H. With a high bulk density, one obtains low porosities or vice versa. Due to the large number of additives, it is often necessary to reduce the deterioration of other product properties, such as i.a. the thermal stability, accept.

Object of the invention

The aim of the invention is the production of polyvinyl chloride with different porosity at relatively high bulk densities.

Explanation of the essence of the invention

- technical task, which is solved by the invention

The object of the invention is to develop a process for the suspension polymerization of vinyl chloride or predominantly vinyl chloride-containing monomer mixtures which, in the presence of known radical-forming initiators or initiator systems, produces polymers with different porosity and relatively high bulk densities.

Features of the invention

The object is achieved in that the suspension stabilizers polysiloxane-polyoxyalkylene block copolymers of the general formulas

H ^ SiO ^ SiE ¹ OV _n G

GE ^ SiO / SiR «0_ / _m / j 0

Hj ₁ SiO / SiH: '0_ / _{m / 3}

, J

I

/ LH'O G

SiEj y _{n / 2}

SiH

in which mean:

R '- identical or different lower, optionally substituted alkyl radicals; preferably methyl groups m - integer fractionated numbers between 1 and 12, preferably between 2 and 5 η - integers or fractions between 30 and 250, preferably between 40 and 120 G - polyoxyalkylene glycol acetate oil, alkoxylate, cyanoalkoxylate or ureate radical of general formula - [CH ₂ I ₃ - [OCH ₂ CH ₂ ] P- [OCH ₂ CH (CH ₃ ) Ic-R '

R '-OCOCH ₃₁ -OK-OCH ₃₁ -OC ₄ H ₉₁ -OCH ₂ -CH ₂ Cn ₁ OCONHR ", R" alkyl or aryl radical

p, q integer-breaknumbers between4 and 50

in concentrations of between 0.001 and 0.3% by weight, based on the aqueous phase, and in that the polymerization is carried out in two sections, the first polymerization section being limited to a conversion of up to 20% and depending on the desired K value is carried out at a temperature which is above or below the polymerization temperature corresponding to the K value, while the second polymerization is carried out at the polymerization temperature corresponding to the K value.

embodiments Example 1 to 2

An oxygen-free rinse autoclave was charged with 400 parts of water, 200 parts of vinyl chloride, 0.15 parts of lauroyl peroxide, 0.1 parts of dicetyl peroxydicarbonate and 0.05 wt .-% based on the aqueous phase of polysiloxane-polyoxyalkylene block copolymers. The polymerization was carried out at the temperature and time indicated in Table 1.

Example 3 to 4

An oxygen-free rinse autoclave was charged with 400 parts of water, 200 parts of vinyl chloride, 0.1 part of lauroyl peroxide, 0.3 part of dicetyl peroxydicarbonate and 0.05 wt% of polysiloxane-polyoxyalkylene block copolymers. The polymerization was carried out at the temperature and time indicated in Table 1.

Table 1 1. Polymerization Time min. 2. Polymerization bulk centrifugal av. distri K value at section section mass genweich- grain lungs- game Temp. ⁰ C Temp. ⁰ C g / i macher- by width - admission knife 30 % μΓΠ 62.5 - 63 612 22.2 161 1.49 62.8 1 54 30 63 502 24.7 148 1.89 70.3 2 - 54 384 32.3 172 1.89 68.5 3 63 54 510 29.7 180 1.86 4

c - average grain diameter of the gas distribution F - distribution width calculated according to:

d - grain diameter

G - Sum weight of the sieve fraction

Claims (1)

1. A process for the preparation of polymers of vinyl chloride by free radical polymerization of vinyl chloride and monomer mixtures predominantly containing vinyl chloride in the presence of known radical-forming initiators or initiator systems by the suspension process, characterized in that as suspension stabilizers polysiloxane-polyoxyalkylene block copolymers of the general formulas, RJSiO / SiH ¹ O 7 _m G
or GRJSiO / SiE'0 / _m / SiR ₂ O / _{q / 2} - SiEJG G
or RJSiO / Si 0 G in which mean: R '- identical or different lower, optionally substituted alkyl radicals; preferably methyl groups m - integers or fractions between 1 and 12, preferably between 2 and 5 η - integers or fractions between 30 and 250, preferably between 40 and 120 G - polyoxyalkylene glycol acetate, oil, alkoxylate, cyano alkoxylate or ureate radical general formula - [CH ₂ ] ₃ - [OCH ₂ CH ₂ ] _p - [OCH ₂ CH (CH ₃ )] _q -R ' R 'is -OCOCH ₃ , -OH ₁ -OCH ₃ , -OC ₄ H ₉ , -OCH ₂ -CH ₂ CN, -OCONH R "R" alkyl or aryl radical p, q whole or fractional numbers between 4 and 50 in concentrations between 0.001 to 0.3 wt .-% _f based on the aqueous phase can be used. A method according to item 1, characterized in that the polymerization is carried out in two sections, wherein the first polymerization is limited to a conversion to 20% and, depending on the desired K value, carried out at a temperature above or below the K value corresponding polymerization temperature, while the second polymerization is carried out at the polymerization temperature corresponding to the K value.