DE1184958B - Process for the production of homopolymers or copolymers of vinyl esters - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school KL: C08f

German KL: 39 c- 25/01

Number: 1184 958

File number: F37386IVd / 39c

Filing date: July 21, 1962

Opening day: January 7, 1965

It is known that polyvinyl esters or vinyl ester copolymers can be used can be prepared by polymerization in bulk or in solution.

The continuous polymerization in bulk can, for. B. carried out according to the tower method will. In solvent polymerization, peroxides are generally used as catalysts. The chain length of the polymers can be determined by the amount of catalyst used is, also by so-called chain transmitters, ζ. Β. ίο lower aliphatic aldehydes, regulate. However, the polymers obtained by this process are mostly yellowish and have a characteristic odor of the aldehyde or aldehydes used, after aldehyde condensation products and reaction products of the aldehyde or aldehydes with peroxides. The solvent polymerization is particularly useful when using polymers with K values (K values according to H. F i k e η t s c h e r, 1% strength measured in ethyl acetate; Cellulosechemie, Vol. 13, p. 58 [1932]) wants to get in the range of about 30 to 70, mostly carried out in special boilers. As a solvent alcohols, esters or aromatic hydrocarbons are used. So it is from the USA patent specification 2,582,055 known that vinyl acetate can be polymerized in isopropanol. Furthermore, the USA.-Patent 2 007 557 to infer that a polymerization in the presence of organic Can carry out diluents or in the presence of preformed polymers and that this gives polymers with a low molecular weight. The quality of the after the solvent polymerization process produced products is generally better than that obtained by a bulk polymerization process. However, there are other serious disadvantages with the solvent polymerization process. The reaction speed is slower. The space and time yield is worse, since most of the time not completely polymerized. The use of large amounts of solvent is also costly and dangerous and requires special security measures.

It should also be pointed out that the chain-transferring effect of the alcohols, used up to now in solvent polymerization is lower than that of aldehydes.

According to an earlier proposal, it was found that excellent polymers of vinyl esters are obtained if the polymerization in a secondary aliphatic alcohol or in a mixture of a secondary aliphatic alcohol is used for the preparation of homo- or
Copolymers of vinyl esters

Applicant:

Farbwerke Hoechst Aktiengesellschaft
formerly Master Lucius & Brüning,
Frankfurt / M., Brüningstr. 45

Named as inventor:

Dr. Werner Ehmann, Frankfurt / M .;

Dr. Heinrich Freudenberger,

Bad Soden (Taunus);

Dr. Karlheinz Kahrs, Frankfurt / M.

and water and initially only part of the monomer or monomers polymerized and then only the apparent amount of monomers to which no secondary alcohol has been added is added. To this process gives polymers with very low K values in particular, since they are secondary Alcohols do not cause pronounced chain transfer.

There has now been a process for the preparation of homopolymers of vinyl esters and of copolymers of vinyl esters with other olefinically unsaturated compounds by polymerizing the Monomers in one or more secondary aliphatic alcohols or a mixture of one or more aliphatic alcohols with up to 20% water, in which initially only part of the or the monomers is partially polymerized, found, in which one also very valuable vinyl ester polymers receives, especially those with a K value in a medium range, e.g. B. from 30 to 70, if the remaining amount of monomers together with further amounts of secondary aliphatic Alcohol adds and the concentration of secondary aliphatic alcohol in the polymerizing mixture is always higher than in the mixture added later.

According to this procedure, the K value can be regulated over a wide range, and the values obtained Polymers are distinguished by their particular purity and freedom from odor and taste and are therefore extremely versatile

409 767/416

bar. The following are three process options for solvent polymerization contrasted by vinyl acetate. It was under comparable test conditions with changing Amounts of isopropanol worked.

Procedure I:

Vinyl acetate, bisazoisobutyronitrile (ABN) and isopropanol were used together and all at once added to the polymerization vessel.

Procedure II:

Vinyl acetate, bisazoisobutyronitrile (ABN) and isopropanol were in a storage vessel mixed and poured a quarter of this mixture into the polymerization vessel and the remainder of the mixture is metered in as the polymerization progresses.

Method III (method according to the invention):

Three quarters of the isopropanol was added to the polymerization vessel. In the storage jar was the vinyl acetate, the last quarter of the isopropanol and the bisazoisobutyronitrile (ABN) mixed and poured a quarter of it into the polymerization vessel. The rest was after Metered in according to the polymerization.

The table gives the K values of the polymers obtained.

Table 1

Relatively low molecular weight products are therefore obtained or, in other words, relatively little is required Isopropanol to produce products with a certain K value.

To show again that there is a marked reduction in the K value in the production of polyvinyl esters or polyvinyl ester copolymers occurs when one polymerizes that in the polymerization vessel a higher concentration of secondary

ίο aliphatic alcohol is present than in that the monomers flowing in during the polymerization, the above-described process I, II and III also carried out using methanol and n-propanol, respectively. The K values of the obtained Polymers are compared with one another in the table below.

° / o alcohol based on
Vinyl acetate

3 ¹¹ Z ₀ iso- 3% n-Pro-; 3% methpropanol panol anol

60 80 . 86 59 79 I 82 42 73 ! 80

0 1 / 0 isopropanol, based i 2 ^{3 4th} on 5 80 Vinyl acetate ¹ 69 60 57 52 80 ! 67 59 53 47 71 1 58 42 39 37

Procedure I.
Procedure II.
Procedure III

When submitting part of the isopropanol, i. H. when the concentration in the polymerization vessel increases Isopropanol is higher than in the monomer flowing in during the polymerization, a unexpectedly pronounced decrease in the molecular weight of the polymer. This appearance is technically very important and practically usable.

If only part of the isopropanol is initially charged and if the concentration in the polymerization vessel is too high Isopropanol is higher than the amount of monomer flowing in during the polymerization, a as can be seen from the table, pronounced lowering of the molecular weight of the polymerization process, which together with other very valuable properties of the polymer, e.g. B. its odorlessness and its colorlessness, of is of considerable technical importance.

The process according to the invention can be carried out both batchwise and continuously. At the z. B. continuous polymerization of vinyl acetate in the presence of isopropanol in a vertical tube, the upper part of which is under reflux, isopropanol accumulates in this part of the apparatus in the steady state of continuous polymerization. The concentration there is therefore higher than that in the incoming monomers and that in the outflowing polymer. Procedure I ..
Procedure II
Procedure III

It is generally advantageous, depending on the type of monomer and the desired molecular weight 0.5 to 20% of one or more secondary aliphatic alcohols, preferably isopropanol, based on the total weight of the solvent and the monomers, but preferably 1 to 8% ^using . The process according to the invention can also be carried out in the presence of water. Up to 20% of water, based on the alcohol or alcohols, can be present without the advantages of the process according to the invention being lost.

The polymers prepared according to the invention are, as already stated, compared to those according to conventional processes, in particular with the addition of aldehyde regulators, produced practically colorless and odorless and they continue to give less discolored saponification products than the saponification the previously known method produced. Copolymers produced by the new process unlike those produced with the aid of aldehyde regulators, are not or less crosslinked and therefore show more favorable solution properties. As catalysts in the inventive Process known per se, which involve free radical polymerization in bulk or in release organic solvents, can be used, e.g. B. Diacylperoxides and with special Advantage of azo compounds such as bisazoisobutyronitrile.

For the production of vinyl ester copolymers, all those which are copolymerizable with vinyl esters are suitable Connections, e.g. B. esters of fumaric acid, esters of maleic acid, also crotonic acid. A preferred one An embodiment of the process according to the invention is continuous polymerization. It is in general expedient to carry out the polymerization under inert gases, such as nitrogen.

The polymerization temperatures are as long as the polymerization feed is still stirrable, are generally between 40 and 9O ⁰ C. For complete complete polymerization of the monomer, it is generally advantageous to increase the polymerization temperature can last up to 130 ⁰ C.

example 1

a) 400 g of vinyl acetate are polymerized by the process III described further above.

Three quarters of the amount of isopropanol given in Table 1 above is poured into a 1-1 bottle, which is equipped with a powerful stirrer and a reflux condenser. 100 g of a mixture prepared in a storage vessel and consisting of a quarter of the amount of isopropanol given in Table 1, 400 g of vinyl acetate and 0.8 g of ABN are then added. The mixture is then polymerized at 80 ⁰ C external temperature until the mixture has a viscosity reaches about 1000 poises. Then the mixture still contained therein is added dropwise from the storage vessel in such a way that the viscosity of the polymerizing mass remains constant at a value of about 1000 poises until the end of the addition. After completion of the polymerization, the bottle is strongly cooled, crushed, the contents dissolved in ethyl acetate to about 20 ° / ₀ solution diluted one part thereof to 1%, and this part is used for K-value determination.

b) For comparison, carrying out the polymerization according to process I.

400 g of vinyl acetate, 0.8 g of ABN, and as much percent isopropanol, as indicated in Table 1 are polymerized in a manner as described in Example a) apparatus at 8O ⁰ C external temperature. Then, as described in Example 1, a), worked up.

c) For comparison, carrying out the polymerization according to process II described above.

400 g of vinyl acetate, 0.8 g of ABN and as much percentage of isopropanol as indicated in Table 1 are mixed and 100 g of this mixture are introduced into an apparatus as described in Example 1, a). These are polymerized at 8O g 100 ⁰ C external temperature until the viscosity of the mass is about 1000 poise. The remainder of the mixture is then added dropwise in such a way that the viscosity remains approximately constant at the specified value until the end of the addition. After the end of the polymerization, the product is worked up as described in Example 1, a).

Example 2

45

Apparatus: A vertical, thin-walled glass tube with a clear width of 50 mm and a length of 1.5 m. The tube carries a reflux condenser and a dropping funnel at its upper end. The pipe will heated from the outside by a water bath, the height of which is equal to the height of the material to be polymerized in the Pipe is.

A mixture of 1.5 kg of vinyl acetate, 45 g of isopropanol and 3 g of ABN is polymerized.

From this mixture 100 g are initially submitted and in the tube at 80 ° C outside temperature up to one Polymerized viscosity of about 1000 poises. Then the above mixture is tapered to the same extent left that the viscosity at the surface of the polymerizing mixture is approximately maintained. The tube gradually fills with polymer. The isopropanol preferably distills upwards, see above that there is always a higher one in the reflux and thus in the upper, lower-viscosity polymer melt Percentage of isopropanol is in the feed and in the lower part of the pipe, in which the polymerization is complete took place.

When the tube was filled, polymerization was continued for 2 hours, then the tube was cooled, the glass was knocked off, the polymer rod cut up and the K values of the polymer at various levels certainly. Polymer with a K value of 61 had formed at the bottom of the tube. Up to a pipe height of around 50 cm the K-value fell and then remained constant at 53. So you can say that the steady state had set. If one compares with the values in table 1, then this value lies between the values according to method II and III when using 3% isopropanol.

In principle it is possible to continue this experiment continuously by starting from below beginning, parts of the tube removed during the polymerization or the tube further increased at the top. The arrangement described was chosen because it is difficult with small amounts of substance to a to achieve continuous outflow of a viscous polymer melt from a tube.

Example 3 Production of a copolymer

2.5 g of isopropanol, 0.4 g of water and 100 g are placed in an apparatus as described in Example 1, a) of a mixture consisting of 320 g vinyl acetate, 80 g maleic acid dibutyl ester, 0.9 g isopropanol, 0.2 g Water and 0.8 g ABN, brought.

When polymerizing at 85 ° C outside temperature, the mixture in the bottle has a viscosity of about 2000 poises, the remaining solution is allowed to run in so that the viscosity is about remains constant. After the polymerization is complete, work-up is carried out as described in Example 1, a). The K value of the polymer is 58.

Claims (1)

Claim: Process for the production of homopolymers of vinyl esters and of copolymers of vinyl esters with other olefinically unsaturated compounds by polymerization of the monomers in one or more secondary aliphatic alcohols or a mixture of one or more secondary aliphatic alcohols with up to 20% water, in which initially only part of the monomer (s) is / are polymerized, characterized in that that the remaining amount of monomers is added together with further amounts of secondary aliphatic alcohol and the Concentration of secondary aliphatic alcohol in the polymerizing mixture is always higher than in the mixture added later. References considered: U.S. Patent Nos. 2,007,557, 2,582,055. 409 767/416 12. 64 © Bundesdruckerei Berlin