DE2827925A1 - PROCESS FOR THE PREPARATION OF POLYMERIZATES FROM ETHYLENIC UNSATURIZED MONOMERS - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

□! PL ING

DR-INQ

3 W. STOCKMAIR

DrL-ING-AaE [CALTEOH)

K. SCHUMANN

Dft RER NAT. ■ DIPL-PHYS.

P. H. JAKOB

DlPL-ING.

<3. BEZOLD

DR RER NAT DPL-CHEM.

8 MUNICH 22

MAXIMILIANSTRASSE 43

June 26, 1978 P 12 620 - 60 / co

CONTINENTAL OIL COMPANY

P.O.Box 126?

Pon'ca City, Oklahoma 7 ^ 601, Y.St.A.

Process for the production of polymers from ethylenic

unsaturated monomers

The invention relates to the production of polymers from ethylenically unsaturated monomers by free radical suspension polymerization.

The preparation of polymers by suspension polymerization of one or more ethylenically unsaturated monomers has been around since known for a long time. The method consists in that a jacketed reaction vessel with water, the monomer or monomers, a Charged initiator and a disperser. The reaction mixture is stirred in the customary manner. Carrying out the polymerization is done by sending hot water or steam through the jacket of the reaction vessel until the desired reaction temperature is reached is reached. Once the desired temperature has been reached, the conversion is controlled via the heating jacket. Man

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lets the reaction run until a given conversion is reached. The polymerization is then terminated by adding chain terminators and / or releasing the pressure in the reaction vessel.

A problem with typical polymerization processes is the formation of reaction products, which are oversized, gel and glassy Contain particles.

A process for the production of polyvinyl chloride is known from the prior art, in which the polymerization of vinyl chloride takes place in substance in a reaction vessel equipped with two stirrers, one of which during the polymerization the first 7 to 12 percent of the vinyl chloride is running at high speed; the other stirrer runs during the remainder of the reaction at low speed, so that a uniform heat distribution takes place in the reaction mass.

According to this known process, polyvinyl chloride is formed smaller particle size and larger apparent density if fast in the first few hours of polymerization Stirring takes place and the stirring is slowed down in the final stage (but still strong enough to ensure good heat transfer to ensure).

According to DE-OS 20 02 380 "polymer particles are more uniform Size also formed by partial polymerization with vigorous stirring, whereupon the further polymerization takes place moderate stirring.

In US Pat. No. 3,882,195 there is a very special method of manufacture of polyvinyl chloride, in which the initiator is added after pre-emulsification of the vinyl chloride. According to of this patent provides the "pre-emulsification of vinyl chloride in the presence of a polyvalent metal ion, a surfactant Substance and a primary polymer with subsequent polymerization by subsequent addition of initiator a high degree

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control of the physical properties of the polymer obtained, which are reproducible at the same time. By adding surface-active substances in the course of the polymerization, the stability is improved. "

There has now been an improved method of suspension polymerization found that reduces the aforementioned problems of oversize, gel and glassy particle formation.

According to the invention, the procedure here is to remove the reaction mixture stir for a short period of time, before significant polymerization of the reactants takes place.

The prior art acknowledged above differs in this respect of the method of the invention than in the prior art two-stage stirring, i.e. two-stage stirring with different Speed. In particular, the measure of the method according to the invention is not described or suggested in the prior art, after which the initiator is added after a first stirring stage.

The invention thus relates to an improvement in manufacture of polymers made from ethylenically unsaturated monomers by free-radical suspension polymerization. The improvement is there summarized in that the reaction mixture is stirred before substantial polymerization of the reactants takes place. Here in one embodiment, the reaction mixture is at the polymerization temperature or at a lower temperature before the initiator is added and the polymerization begins. In another embodiment, the reaction mixture is stirred at low temperature in the presence of the initiator and then increases the temperature to the polymerization temperature. That Process leads to a polymer with improved properties.

The invention thus relates to a process for the production of polymers with improved properties through an improvement in the suspension polymerization of one or more ethyl

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nically unsaturated monomers, with stirring during the polymerization. The method is characterized in that one the reaction mixture is stirred before substantial polymerization of the reactants occurs.

In one embodiment of the invention, the reaction mixture stirred at the polymerization temperature or a lower temperature before adding the initiator and the polymerization begins.

In another embodiment of the invention, the reaction mixture is at low temperature (e.g. 25 ° C) in the presence of the Stirred initiator before increasing the temperature of the reaction mixture to the polymerization temperature.

According to the invention, one or more ethylenically unsaturated Monomers used for the production of polymers, copolymers or terpolymers.

Examples of ethylenically unsaturated ones suitable according to the invention Monomers are vinyl halides such as vinyl chloride, vinyl bromide and vinyl fluoride; Vinylidene chloride; Vinyl acetate; Vinyl alkyl esters (such as vinyl neodecanoate); Ethylene; Propylene; Isobutylene; Acrylonitrile; Styrene; Esters of acrylic and methacrylic acid, v / ie methyl, ethyl, butyl, Propyl, 2-ethylhexyl or hexyl acrylate and methacrylate; or Esters of maleic acid, v / ie diethyl, dipropyl, dihexyl and dioctyl maleate.

Vinyl chloride is preferred, which is exemplified below for the Description of the invention is used.

For the implementation of the method of the invention are those for Suspension polymerization of ethylenically unsaturated monomers is common Suitable initiators. Examples include organic peroxides such as benzoyl peroxide and lauroyl peroxide; Peroxydicarbonates, such as di- (sec-butyl) peroxydicarbonate, di- (2-ethylhexyl) peroxydicarbonate, Diisopropyl peroxydicarbonate / di (n-propyl) peroxydicarbonate, dicetyl peroxydicarbonate and dicyclohexyl peroxydicarbonate;

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Peroxyesters, such as tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, 2,5-dimethyl-2,5-bis- (2-ethyl-hexanoylperoxy) -hexane and tert-butyl peroctoate; Azo compounds such as azobisisobutyronitrile; and other oil soluble initiators.

Even those in the suspension polymerization of ethylenically unsaturated Monomers customary dispersants can be used. Examples of suitable dispersants are natural high molecular weight Substances such as starch and gelatine, as well as synthetic high-molecular substances such as partially saponified polyvinyl alcohol, Methyl cellulose, ethyl cellulose, hydroxypropoxymethyl cellulose, Maleic anhydride vinyl ether copolymers, polyvinylpyrrolidine, Polyvinyl pyrrolidone, and the like.

With regard to the proportions of water, monomers, initiators and dispersants that are used in suspension polymerization Use, reference is made to the relevant literature.

The reaction mixture is stirred by means of conventional equipment (e.g. with turbine stirrers or special stirrers (retreat curve stirrer), with or without baffles). Here, in agitated at different speeds during the various phases of the process; however, this is not required. Accordingly, usually during the entire course of the procedure stirred at a constant speed.

An important feature of the process of the invention is that the reaction mixture be stirred for a short period of time before significant polymerization of the reactants occurs. As used herein, the term "substantial" refers to polymerization to 1 percent or less as measured by monomer conversion.

In one embodiment of the invention, the reaction mixture is at the polymerization temperature or a lower temperature stirred before adding the initiator and the polymerization begins. In another embodiment, stir at a lower level Temperature in the presence of an initiator before setting the temperature

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increased to the polymerization temperature.

Stirring the reaction mixture before any significant occurrence Polymerization of the reactants is hereinafter also referred to as "pre-stirring".

The reaction temperature is about 45 to 75 ^° C. You can also ^{go down to about 40 °} C., although lower temperatures are less preferred since they require a longer duration of the polymerization and increased amounts of initiator.

The following factors determine whether there is significant polymerization takes place or not: presence of initiator, amount of initiator, Type of initiator, temperature, time and size of the reaction vessel . The person skilled in the art can easily determine the conditions for pre-stirring from the information provided. Below however, some information is given in this regard by way of example.

The time for the pre-agitation is, for example, about 1 to about 45 minutes. You can stir for longer than 45 minutes; however, this is neither necessary nor economical. The pre-stirring time is preferably about 10 to about 20 minutes.

In the absence of initiator, the temperature of the mixture may be below the polymerization temperature during the Vorrührens somewhere in the range of up to 25 ⁰ C (eg, 15 ⁰ C). When the Vorrührtemperatur is 45 ⁰ C, or higher, it is preferred to have no initiator present. If the Vorrührtemperatur is 35 ⁰ C or lower, the presence of the initiator is not particularly important, that the initiator can be present or abxvesend.

The remainder of the procedure takes place under normal conditions suspension polymerization.

The examples illustrate the invention.

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example 1

In this example, two tests are carried out under conventional conditions (at 57 ^° C.). Furthermore, two experiments are carried out in which the temperature is ^{kept at 27 °} C. for 30 minutes. The temperature is then increased to 57 ° C. The stirring speed is the same in both series of experiments.

The following relative starting quantities are used:

Component parts

Vinyl chloride 100

Water 180

Dispersant ^a '0.083

Initiator ^b * 0.121

Hydroxypropyl methyl cellulose

Di (2-ethylhexyl) peroxydicarbonate

The particle size is determined by subjecting 100 g of the polymer obtained to a sieve analysis. The number of glassy Particles seen in a roller head is determined. The results are compiled in the table below.

Standard attempts

Grain size, 250 μτη 149 105 74 PAN large gla-
sxge part
chen Attempt no. 420 12th
10 177 15th
9 12th
6th 4th
3 1
1 A.
B. 8th
7th 48
55 (D
50-75

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Experiments at low temperature (first stage)

Grain size, around 77 149 105 74 PAN large gla 51 17th 15th 3 2 sige part 54 20th 15th 5 2 chen Attempt no. 420 250 1 C. 1 11 (D D. 0 4 0

(1) not determined.

It should be noted in the results that particles with a grain size of over 420 and over 250μπι are undesirable. Both In standard tests, a total of 47 g of particles of this size are obtained. In contrast, the tests with lower Temperature in the first stage and before the addition of the initiator only a total of 16 g of particles of this size. Furthermore a marked improvement in the number of large glassy particles is observed.

Example 2

This example describes the process of the invention in which the reaction mixture is stirred at the polymerization temperature will. Comparative tests are also included.

The following raw materials are used in both types of experiments:

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17th 237 28 123 18.5 667

Component parts

Vinyl chloride water

Initiator ^a *

b)

Disperser

Di (2-ethylhexyl) peroxydicarbonate - 18.5 parts, dissolved in 172.5 parts of odorless petroleum ether

Hydroxypropyl methyl cellulose - 1.5 percent solution in water

A 40 liter reaction vessel is used for both experiments made of stainless steel used.

Process conditions - pre-agitation

1. Add deionized water and dispersant to the reaction vessel.

2. Close the reaction container and evacuate for 15 minutes.

3. Start of stirring at 200 rpm.

4. Addition of vinyl chloride.

5. Heating the container and its contents to 57 ⁰ C.

6. Stir the contents for 30 minutes.

7. Adding the initiator solution without changing the temperature or of stirring.

8. Carrying out the reaction until the pressure drops ^{to 6.3 kg / cm 2;} then venting and isolation of the polymer.

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Process conditions - no pre-agitation

1. Adding water, dispersant and initiator solution to the reaction vessel.

2. Close the reaction vessel and evacuate for 15 minutes.

3. Start stirring at 200 rpm.

4. Heat the vessel and its contents to 57 ^° C.

5. Adding the vinyl chloride without changing the temperature and of stirring.

6. Carrying out the reaction until the pressure drops ^{to 6.3 kg / cm 2;} then venting and isolation of the polymer.

The results of four attempts, two with and two without pre-agitation, are compiled in the table below.

Attempt pre-stirring sieve analysis, μΐη grain size

no 420 250 177 149 105 74 PAN middle
(around) Default-
deviation 1 Yes 8th 49 18th 8th 8th 7th 2 270 1, 67 2 Yes 0 49 29 8th 9 3 2 243 1.45 3 no 0 29 45 12th 10 3 1 212 1.34 4th 12th 47 19th 8th 6th 5 0 282 1.57

The numerical values for the particle size are from the above examples of the polymers can be seen for four experiments. It can be seen that by pre-stirring the process from the following points of view the grain size distribution is improved:

1. One does not get large particles with more than 420 (in grain size,

2. the mean particle size is reduced by an average of 18 percent, and

3. the breadth of the grain size distribution, measured according to the standard deviation, is reduced by an average of 14 percent.

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Claims (9)

PATENTANWÄLTE A. GRUNECKER DIPL-ING. H. KINKEUDEY DR-INa 9P97QOC W. STOCKMAlR LO L IOCQ DF1-INC-AaE1CALTECHI K. SCHUMANN DR RER ΝΑΓ. · DIPL-PHYS P. H. JAKOB DIPL-tNG. G. BEZOLD DRflERNAX-DIPL-CHEM. 8 MÜNCHEN 22 MAXIMIUANSTRASSE 4-3 June 26, 1978 P 12 620 - 60 / co patent claims 1. Process for the preparation of polymers by suspension polymerization one or more ethylenically unsaturated monomers with stirring during the polymerization, thereby characterized in that the reaction mixture is stirred, before the polymerization reaches a level of 1 percent or less. 2. The method according to claim 1, characterized in that the ethylenically unsaturated monomer is vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinyl acetate, vinyl neodecanoate, ethylene, propylene, isobutylene, acrylonitrile, styrene, methyl acrylate, methyl methacrylate, diethyl maleate, diropyl maleate and / or Dioctyl maleate is used. 3. The method according to claim 2, characterized in that the monomer used is vinyl chloride. 4. The method according to at least one of claims 1 to 3, characterized in that the process is carried out at a temperature in the range of about 45 to about 75 ⁰ C.. 5. The method according to at least one of claims 1 to 4, characterized characterized in that the mixture is at the polymerization temperature or at a lower temperature before adding the initiator and starting the polymerization. 6. The method according to at least one of claims 1 to 5, characterized in that the pre-stirring is carried out at a temperature in the range of about 15 ⁰ C below the polymerization temperature. 7. The method according to at least one of claims 1 to 6, characterized in that the mixture is at a temperature below The polymerization temperature is pre-stirred in the presence of the initiator before the temperature of the reaction mixture is increased to the polymerization temperature. 8. The method according to at least one of claims 1 to 7, characterized in that the pre-stirring for a period of 1 to about 45 minutes. 9. The method according to at least one of claims 1 to 8, characterized in that the pre-stirring in the range of about 15 to 44 ⁰ C is carried out. 909810/0638