DE1048418B - Process for the production of copolymers containing hydroxyl groups from vinyl chloride and a vinyl ester - Google Patents

Description

GERMAN

The invention relates to the transfer of copolymers from vinyl chloride and organic vinyl esters into tertiary copolymers of vinyl chloride, Vinyl esters and vinyl alcohol.

Such copolymers from three components are mainly used in the field of protective coatings (varnishes). The one used so far The manufacturing process consists in that the starting copolymer is in solution brings, this adds an alcohol and an acidic or basic catalyst that the transesterification or the exchange of the hydroxyl groups of the alcohol and the organic acid groups of the polymer favored, and that the solution thus obtained is then heated.

The great disadvantage of this process is the need to dissolve the copolymer in solution bring to. The choice of solvent is very limited; a ketone is generally used. The reaction is slow, because the alcohol has to be in a dilute state for the Polymer, which is otherwise easily precipitated by the alcohol, is kept in solution.

When the reaction is complete, the resulting becomes ternary. Copolymer deposited, filtered, washed and dried. The solvent must consist of a complex mixture, which in addition to the ketone Contains alcohol, acetic acid ester and water generally used for precipitation will. Making the desired. Copolymers are therefore tedious and expensive.

In contrast, the method according to the invention is very much simpler. It consists in that one the saponification is carried out in a heterogeneous phase without the starting copolymer of vinyl chloride and an organic one. Vinyl ester in solution too bring; the copolymers remain in the solid state during the entire work process.

The vinyl chloride-vinyl ester polymer used +0 is a commercial product which, if obtained in suspension, comes in the form of pearls from 0.1 to 1 mm diameter is available. If it has been made in emulsion, it is in the form of a powder before; if the polymerization was carried out in solution with subsequent deposition, then acts there are more or less spongy particles, This starting product is stirred in one. Excess of as possible anhydrous alcohol with a low molecular weight placed in suspension, in which the catalyst used for transesterification is dissolved, which is preferably a strong one Mineral acid, like. Sulfuric or hydrochloric acid, or is a sulfemic acid .. It can also be an anhydrous Process for the production of copolymers containing hydroxyl groups from vinyl chloride and a vinyl ester

Applicant:

PECHINEY, Compagnie de Produits Chimiques et Electrometallurgiques,

Paris

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Pechmann, patent attorneys, Munich 9, Schweigerstr. 2

Claimed priority: France of May 15, 1956

Jean Bisch, La Courneuve, Seine (France), has been named as the inventor

Alkali can be used, such as caustic soda or sodium alcoholate, but this catalyst has the disadvantage of producing colored copolymers.

The mixture is heated to 50 to 80 ° C. with stirring, at or below normal pressure works so that the transesterification between the acidic groups of the copolymer and the Alcohol in the heterogeneous medium formed esters distilled off.

By determining the esters formed, the course of the reaction can be followed and this interrupt when the appropriate degree of saponification is reached. For this it is sufficient to use the catalyst to neutralize. The polymer which has remained dispersed in the solid state is then washed and dried, which offers no difficulty. The excess alcohol is recovered by simply rectifying it.

The rate of reaction depends on the physical state and chemical composition of the starting copolymer from ¹ . It is greater, the more porous the structure of the polymer and the higher its content of vinyl ester groups; is. Other factors that influence the reaction rate are, in particular, the concentration of mixed polymer in the reactant mixture.

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sat and catalyst, the water content of the alcohol and the reaction temperature.

The process can be carried out with all customary vinyl chloride-vinyl ester polymers perform containing 5 to 20% vinyl ester, and is also applicable at higher levels, provided that the Copolymers in which alcohol are insoluble. The most suitable are polymers of vinyl chloride and Vinyl star with 2 to 6 carbon atoms in the Acid group. . . .

In general, the simplest alcohol to use is methyl alcohol, which has particular advantages: Et '. Is by simple rectification, in the anhydrous State available, and its boiling point of 65 ° C at normal pressure is well suited for the reaction. You can also use ethyl or propyl alcohol; because one 'for the purpose of removing the alkyl ester at boiling temperatures must work, but then there is a risk that the> polymer as a result of excessively high temperature decomposed. It is therefore necessary in these cases to work under reduced pressure.

The invention is illustrated by the following examples, in which the parts are parts by weight.

They show the influence of the content of the reaction mixture exerts on the catalyst and water on the reaction rate, and also the different course of the reaction if one of copolymers with different contents of vinyl esters ^ and the rate of reaction of the ester groups with the alcohols as desired varies ..

example 1

A suspension of 40 parts of a copolymer from vinyl chloride and acetate (acetate content 13.5%) is converted into 160 parts of methanol (water content 0.05%) to which 4.5 parts of pure sulfuric acid have been added (acid concentration in the reaction mixture 2.25%), heated to boiling with stirring.

The heating is controlled in such a way that the methyl acetate formed is continuously mixed with a little methanol distilled off. The volume of liquid in the reaction vessel becomes constant by adding appropriate methanol held.

The amount of methyl acetate formed is determined at regular intervals Follow the course of the reaction. Continue as follows:

a) After 7/2 hours you remove approximately the Half of the reaction mixture from the vessel and the acid blunted by a slight excess of sodium acetate. The polymer grains that have retained their shape and become very light Separate by filtration, wash with water to remove any soluble impurities to remove. After drying in the oven, the exact composition of the ternary formed is established by infrared spectrography Copolymer solid. It corresponds to: 89.8% vinyl chloride, 6.2% ■ vinyl acetate, 4.0% vinyl alcohol ;.

As can be seen, the degree of conversion achieved by then amounts to 56.8% of the acetate contained in the 'original copolymer.
^h): The in the _apparatus: remaining portion of the reaction mixture for a further 4 hours under Rüh- 'ren kept boiling. The analysis of the copolymer then removed as above gives the following composition: 91.3% vinyl chloride, 2.8% vinyl acetate,], 5.9% vinyl alcohol.

The overall yield is over 98%. The process therefore works practically quantitatively.

i Example 2

The same amounts of reaction products as in Example 1 are introduced into the device, with but this time a methyl alcohol with a water content of 0.25% was used. After 7/2 hours of heating to 65 ° C! is interrupted. After washing

ίο and drying are obtained in quantitative yield a copolymer of the following composition: 88.6%> vinyl chloride, 8.9% vinyl acetate, 2.5% vinyl alcohol.

From this follows the influence of the water, which in this small one. Content the reaction rate has decreased relatively considerably, since the degree of conversion achieved with the same reaction time was only 35.8% instead of 58.6% as in Example 1.

Example 3

It is worked in the same way and with the same approach as in Example 1, but are on Instead of 4.5 parts of sulfuric acid, only 1.5 parts were added. The degree of conversion is after 7 hours only 15.8%.

Example 4

It is again worked in the same way and with the same approach as in Example 1, wherein but this time a copolymer with 33% (instead of 13.5%) vinyl acetate is used. the The reaction is now much faster, and after 372 hours 51.3% of the acetate groups are saponified. A polymer is obtained with the following composition: 73% vinyl chloride, 17.5% vinyl acetate, 9.5% vinyl alcohol.

Example 5

240 parts of a vinyl chloride-vinyl acetate copolymer with 12.7% acetate are suspended in 360 parts of boiling methyl alcohol with 0.04% water, the reaction mixture being 4 percent by weight Contains sulfuric acid. After the reaction ran for 7 hours as in the previous examples, a copolymer is obtained in a practically quantitative yield, the composition of which is determined by Infrared spectrography was found as follows: 90% vinyl chloride, 5.9% vinyl acetate, 3.7% vinyl alcohol.

This composition corresponds to a degree of conversion of the vinyl acetate from the starting copolymer of 63.1%.

2 »Example 6

40 parts of a vinyl chloride-vinyl acetate copolymer with 13.5% vinyl acetate in 160 parts of boiling methyl alcohol with 0.05% Suspended water content, the reaction mixture containing 2.5 percent by weight of anhydrous hydrochloric acid. After 2 hours, the reaction is interrupted by adding sodium acetate, and a Mixed polymer of the following composition: 87.3% Vinyl chloride, 11.8% vinyl acetate, 0.9% vinyl alcohol. This corresponds to a degree of implementation for the Vinyl acetate from the starting material of 12.6%.

Example 7

It will be the same way and with the same. Approach worked as in Example 1, but the

Claims (6)

10 sulfuric acid as a transesterification catalyst is replaced by a part of anhydrous sodium hydroxide solution. The reaction proceeds very quickly, and after 1 hour the degree of conversion reaches 64.8%, which corresponds to a polymer of the following composition: 90% vinyl chloride, 5.7% vinyl acetate, 4.3% vinyl alcohol. However, the copolymer is discolored, which is not the case with acidic catalysts. Example 8 40 parts of a bead-shaped copolymer with 15% butyrate, which was obtained by copolymerizing vinyl chloride and vinyl butyrate in suspension, are suspended in 160 parts of anhydrous methyl alcohol with 4.5 percent by weight of pure sulfuric acid. The mixture is brought to the boil with vigorous stirring, and some alcohol is allowed to distill off in order to draw off the methyl butyrate as it is formed. After heating for 7 hours, the reaction is interrupted and 37.3 parts of a solid copolymer of the following composition are obtained: 91% vinyl chloride ^. 4.8% vinyl butyrate, 4.2% vinyl alcohol. According to this, 70% of the butyric acid groups were converted into OH groups. P Λ T E N ϊ Λ N S P R C C H E: 1. Process for the preparation of copolymers containing hydroxyl groups by partially Transesterification of a copolymer of vinyl chloride and an organic vinyl ester with an alcohol in the presence of a catalyst, characterized in that the alcohol-insoluble starting copolymer in the lower alcohol used for transesterification, to which the catalyst is added, suspended, the suspension heated with stirring until the The desired degree of conversion is achieved and the polymer which has remained undissolved is separated off. 2. The method according to claim 1, characterized in that the starting copolymer used in the form of pearls, powder or small grains. 3. The method according to claim 1 or 2, characterized in that an alcohol containing fewer than 4 carbon atoms with a water content of less than 0.5%, preferably less than 0.1%, is used. 4. The method according to claim 1 to 3, characterized in that the transesterification when The boiling point of the alcohol and the alkyl ester formed as soon as it is formed distilled off. 5. The method according to claim 1 to 4, characterized in that the transesterification at a Temperature of 50 to 80 ° C carried out, the pressure being adjusted so that the mixture boils within this range. 6. The method according to claim 1 to 5, characterized in that one is used as the transesterification catalyst a strong inorganic acid, especially sulfuric, hydrochloric or phosphoric acid, or a Sulphonic acid or a strong base, especially caustic potash or soda or sodium alcoholate, is used. © 809 728/293 12.