DD256137A1 - PROCESS FOR PREPARING POLYMERS OF VINYL CHLORIDE - Google Patents

Abstract

The invention relates to a process for the preparation of polyvinyl chloride with high Schuettdichte and good Porositaet with reduced formation of Wandansaetzen by the suspension process. The process is designed so that polysiloxane-polyoxyalkylene block copolymers are used as suspension stabilizers and in that the entire initiator necessary for the polymerization is added at temperatures between 313 K up to and including the predetermined polymerization temperature.

Description

txttAöIU / öUx'U / / joUxXV J "/ λ - oxKx \ x

J. (M)

SiR. yn _{/ 2}

0 G

ZSiRJ 7 _{n / 2}

/ SiR'G 0

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 G - polyoxyalkylene glycol acetate, oleic, alkoxylate, cyanoalkoxylate or ureate radical of the general formula

- [CH ₂ ] ₃ - [OCH ₂ CH ₂ ] _p - [OCH ₂ CH (CH ₃ )] _q -R '

R 'is -OCOCH ₃ , -OK-OCH ₃ , -OC ₄ H ₉ , -OCH ₂ -Ch ₂ CN ₁ -OCONHR "R" alkyl or aryl radical

p, q whole or fractional numbers between 4 and 50

in concentrations between 0.001 to 0.3 wt .-% based on the aqueous phase are used and that the entire initiator necessary for the polymerization is added at temperatures between 313 ° C up to and including the predetermined polymerization temperature.

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 chlorides 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 grain, in particular its porosity, the particle size distribution, or the thermal stability 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 so that in the improvement of one size, the worse is usually the other

entry. ''

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

It is also 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, 2151 703, DE-PS 1 545179 , DE-OS 2244905, 2134604).

Also described is the combination of suspension stabilizers for influencing the plasticizer receptivity (US Pat. No. 3,879,365, DE-AS 1 720328, DE-OS 2209892).

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 having 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, i. 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. Take the thermal stability into account.

Object of the invention

The aim of the invention is to produce polyvinyl chloride with high bulk density and good porosity by the suspension process with reduced formation of wall deposits.

Explanation of the essence of the invention

the technical problem 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 with reduced formation of wall deposits, which makes it possible to produce polymers in the presence of known radical-forming initiators or initiator systems which, in addition to an increased bulk density, produce sufficient Have porosity.

Features of the invention

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

RiSiO ZSiH ¹ O / / SiR'0 J Si G

GSASiO

( "

- α- »σ ίο /

H ^ SiO / SiH'07 _{m / 3} / SiEJO y _{n / 2} / SiHnO

n / 2

(III)

in which mean:

R '- identical or different lower, optionally substituted alkyl radicals; preferably methyl groups m -τ- 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-olefin, alkoxylate, Cyanalkoxylate or ureate radical of general formula - [CH ₂ I ₃ - [OCH ₂ CH ₂ ] P- [OCH ₂ CH (CH ₃ ) Ip-R '

R '-OCOCH ₃ , -OH ₁ -OCH ₃₁ -OC ₄ H ₉ , -OCH ₂ -CH ₂ CN, -OCONHR "

R "is alkyl or aryl radical

p, q whole or fractional numbers between 4 and 50

in concentrations between 0.001 to 0.3 wt .-% based on the aqueous phase, are used and by adding all the initiator necessary for the polymerization at temperatures between 313 K up to and including the predetermined polymerization temperature.

embodiments Example 1 to 2

An oxygen-free rinse autoclave was charged with 400 parts of water, 200 parts of vinyl chloride and 0.05 wt .-% based on the aqueous phase of polysiloxane-polyoxyalkylene block copolymers. The initiator mixture, consisting of 0.15 parts of lauroyl peroxide and 0.1 part of dicetyl peroxydicarbonate, was metered in at the temperature according to Table 1. Polymerization was at 336K.

Example 3 to 4

An oxygen-free rinse autoclave was charged with 400 parts of water, 200 parts of vinyl chloride and 0.05 wt .-% based on the aqueous phase of polysiloxane-polyoxyalkylene block copolymers. The initiator mixture, consisting of 0.1 part of lauroyl peroxide and 0.3 parts of dicetyl peroxydicarbonate, was metered in at the temperature according to Table 1. Polymerization was at 327K.

Example 5 to 6

An oxygen-free rinse autoclave was charged with 400 parts of water, 400 parts of vinyl chloride and 0.05 wt .-% based on the aqueous phase of polysiloxane-polyoxyalkylene block copolymers. The initiator mixture, consisting of 0.15 parts of lauroyl peroxide and 0.25 part of dicetyl peroxydicarbonate, was metered in at the temperature according to Table 1. Polymerization was at 331K.

Table 1 Initiator- Schüttge centrifuge C F K value 62.5 at doserierungs- weight softener μ, ιη t 62 game temperature K g / l admission% 70.3 612 22.2 161 1.49 70 1 333 660 14.0 172 1.51 67.9 2 - 384 32.3 172 1.89 67.4 3 327 451 26.3 170 1.9 4 - 573 27.4 131 1.72 CJL 331 594 25.3 152 1.75 6

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

G _dg5

d - grain diameter G - total weight of the sieve fraction

Claims (1)

1. A process for the preparation of polymers of vinyl chloride by 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 R ^ SiO ZssiE ^f 07 _m / SiRJO (I) G