DD143079A1 - METHOD FOR THE MICROSUSPENSION POLYMERIZATION OF VINYL MONOMERES - Google Patents

Abstract

Method of microsuspension polymerization of vinyl monomers, preferably vinyl chloride, the resulting polymers especially suitable for the preparation of plastisols. The Polymerization takes place by adding a seed latex containing the whole to the Polymerization required initiator and 0.3 to 2.0 Ma .-%, based is presented to the monomer of the seed latex, emulsifier. The Feed of the monomer (s) is such that a polymer-monomer ratio from 0.3 to 0.8, preferably 0.5 to 0.6 is, wherein the emulsifier content in the polymer at the end of the Polymerization <1.0 Ma ···, and during the supply of the Monomers a peripheral speed of the stirrer from 0.4 to 1.0 m · s "1 'is maintained. The advantage of the invention Procedure consists in a substantial improvement of Space-time yield in the polymerization and in a reduction of the Residual emulsifier content in the polymer.

Description

253

Title of the invention

Method for microsuspension polymerization of vinyl mono mers a

Field of application of the invention

The invention relates to a process for the microsuspension of vinyl monomers, preferably vinyl chloride, wherein the resulting polymers are particularly suitable for the preparation of Piastt-: ^r -ols.

_ ₂ _ 212 253

Characteristic of the known technical solutions

It is known to polymerize vinyl monomers in particular vinyl chloride according to the principle of microsuspension, this process is carried out by a certain characteristics containing seed latex, which contains the entire amount required for the final polymerization initiator, and further polymerized after a single addition of the monomer to its conversion becomes. (DB-AS 1745220).

This method has the disadvantage that the polymerization process at the beginning is very slow and therefore the v / poor from leading. It is disadvantageous that in order to stabilize the dispersion and to introduce the entire monomer, it is necessary to use increased amounts of emulsifier.

It is also known to provide as seed latex a mixture of latices of different particle sizes, one of the latex components being prepared by emulsion polymerization. (DE-OS 2618761). _;

The disadvantage of this method is that in addition a separate process is required for the preparation of the aforementioned seed latex. Moreover, the abovementioned disadvantages which relate to the beginning of the polymerization are not eliminated.

In another known method, metal salts and organic complexing agents are added to the polymerization batch in order to increase the reaction rate in the starting phase. (DE-OS 2427385).

The disadvantage of this method is that the thermal stability of the resulting polymers is reduced. As a result, the possible applications of the polymers are restricted.

t12 2s3

Object of the invention

The object of the invention is to carry out the microsuspension of Vinylmonoiaeren, preferably of vinyl chloride with improved space-time yield and produce polymers which have a low residual emulsifier content and are suitable for the preparation of low-viscosity plastisols or pastes.

the essence of the invention

The technical problem to be solved by the invention The object of the invention is to develop a process for the microsuspension polymerization of vinyl monomers, preferably vinyl chloride, which makes it possible to carry out the polymerization with improved space-time trapping, with polymers having a low emulsifier content , which are suitable for the preparation of low-viscosity pastes or plastisols obtained v / earth. In this case, first of all a seed latex is prepared which contains all the initiator required for the further polymerization and 0.3-2.0% by weight, based on the amount of monomer used, of emulsifier, while the monomer is added with stirring.

- Features of the invention _: The object is achieved according to the invention by feeding the monomer (s) in such a way that a polymer-monomer ratio of 0.3 to 0.8, preferably 0.5 to 0.6, during the polymerization is maintained, wherein the Einulgatorgehalt in the polymer at the end of the polymerization K is 1% and during the supply of the monomer peripheral velocity

-1

is maintained from 0.4 to 1.0 m.sek.

Examples

The invention will be explained in more detail with reference to the following examples.

- * - 2t 2 253

example 1

In a stirred reactor 360 Tl. Vinyl chloride, 900 Tl ₀ Water, '3 Tl. Alkylsulfonate and 0.72 Tl lauroyl peroxide are added and dispersed using a suitable homogenizer to give a fine emulsion.. Eei 52 ° C results after 8 hours of polymerization, a latex of 25.2 % solids, from this dispersion in a further stirred tank 1000 Tl are added and then fed 200 Tl. Vinyl chloride. The stirrer is set for 10 minutes to a peripheral speed of 1 § and then at 0.2 m / s and 52 ° G, the polymerization 'started. After ~ 1 hour at achieving maximum reaction rate of vinyl chloride ₀ / h with a metering pump, the monomer is over a period of about 4 hours at a Rührerumfangsgeschwindigkeit of r- * 0.6 m / s retracted with a power of 80 Tl. Thereafter, the VC feed is stopped, the stirrer is set at a rate of 0.2 m / s, and the polymerization is continued until the pressure drops after a total of 6 hours of Pm time. The total polymerization time of both Pm stages including charging times is 16 hours. The result is a dispersion having a solids content of 48.3 % _t worked up by spray drying a powder results, which in admixture with the plasticizer DOP in the ratio 60: 40 to a viscosity at D =

-1 48.6 s from 2 ^ 40 mPas leads. The emulsifier content in the powder; is 0.4 % _t, which provides a water absorption of the foils produced from the pastes of only 0.2 mg / cm.

Example 2

The starting latex is prepared as in Example 1. Of this, 1-000 parts by weight are placed in a stirred tank, 200 parts of vinyl chloride are added, 10 minutes are applied at a peripheral speed.

~ stirred and then at 0.2 ~ and 52 °

ίο ..ίο

polymerized to the beginning temperature or pressure drop,

1 - stirred and then at 0.2 - and 52 C to

: 2t 2 253

Then again at peripheral speeds of 1 ^ 100 Tl,

Vinyl chloride metered, at 0.2 - polymerized until incipient pressure or temperature drop. These Veriserisschritte be repeated three times, so that there is a PesDstoffgehalt of 48.8 % . The total polymerization time including charging times is 18 hours. The quality of the products produced therefrom corresponds to the parameters given in Example 1. ;

Example 3

A .Vinylchlorid / water emulsion prepared according to Example 1 is polymerized until it reaches the gel phase. Then, at stirrer primary velocities of 0.6 ~, a feed of vinyl chloride is effected by means of a metering pump at a capacity of 80 parts / h. After 7 hours, the metering is stopped, the stirrer peripheral speed is set to 0.2 f and up to temperature or Pressure drop polymerized. It is achieved a solids content of 47.9 % . The total polymerization time including charging times is 14 hours.

The quality of the products produced therefrom corresponds to the parameters given in Example 1.

Example 4

The procedure corresponds to Example 3. However, over a period of 9 hours per 80 parts of vinyl chloride retracted. Here it is necessary, after 4 and 8 hours each 0.2 % Alkylsuli'onat bez. a. Add total monomer. It results in a solids content of 52 Yo ₉ The paste viscosity corresponds to Example 1, the emulsifier, is 0.4 ^ % with a water absorption of the film of 0.25 mg / qm.

- 6-

.412 2S3

Example 5 (Comparative Example )

The starting latex is prepared as in Example 1. 1000 parts of this are placed in a stirred kettle, 0.6 % alkylsulfonate. a. retracted monomer and 600 parts of vinyl chloride, stirred for 30 minutes at a peripheral speed of 1 ~ and then at 52 ° C and a peripheral speed of the stirrer from 0.2 - to Temperaturbzv /. Pressure drop polymerized. The Gesamtpolymerisationsze.it · including charging times is 22 hours. The solids content of the dispersion is 47.8 %,

The paste viscosity gives a value at D = 48.6 s of 2380 mPas, the emulsifier content of the powder is 0.9% »what one

Water absorption of the film of 0.48 mg / cm corresponds.

Claims (1)

Erfindungsansoruch A process for the microsuspension of vinyl mononers, preferably vinyl chloride, wherein the polymers obtained are particularly suitable for the preparation of plastisols, by a seed latex, the total initiator necessary for the polymerization and 0.3 to 2.0 mass%, based on the monomer of Seed latex containing emulsifier, characterized in that the feed of the monomer (s) is such that a polymer to monomer ratio of 0.3 to 0.8, preferably 0.5 to 0.6 is maintained the emulsifier is in the polymer at the end of the polymerization <! 1.0% by mass and during the feeding of the monomer a peripheral speed of the stirrer of 0.4 to 1.0 m.sec is complied with,