DE862511C - Process for stabilizing vinyl chloride polymers - Google Patents

Description

The present invention relates to improvements in the preparation of mixtures and Polyvinyl chloride masses.

During the thermal decomposition of polyvinyl chloride, hydrogen chloride is formed and it becomes assumed that the free hydrogen chloride present in the polymer is responsible for further decomposition of the polymer catalyzed. About the decomposition of the polyvinyl chloride at higher temperatures to reduce, various stabilizers have already been proposed as additives. Metal soaps have been used for this purpose, and in particular lead stearate, the The effect of the stabilizers is that they react with the free hydrogen chloride in the polymer combine and metal chloride and fatty acid are formed.

Lead stearate is a very effective compound as a stabilizer; however, it has the disadvantage that the stearic acid formed by the action of hydrogen chloride and also the bleach chloride in of the polyvinyl chloride composition are not soluble, and therefore it is polyvinyl chloride stabilized with lead stearate always cloudy and opaque.

It has also been proposed to make the metal halide formed from the stabilizer soluble and onnect for this purpose the metal moiety of the stabilizer with a sufficiently large alkyl to \ ^r. A particular example of such a stabilizer is dibutyltin dilaurate. This compound decomposes on reaction with hydrogen chloride to form dibutyltin dichloride and lauric acid. This compound has the advantage that the organometal halide is soluble in the polymer;

however, it has the disadvantage that lauric acid is incompatible with the polymer and that as a result when using dibutyltin dilaurate Obtained in amounts of about Ί percent by weight and more cloudy, cloudy polymeric masses will. The di'butyltin dilaurate is, however, a good stabilizer, if only in very small amounts Concentrations need to be applied or if the transparency of the polyvinyl chloride is of little importance.

While the disadvantage of the use has been eliminated by the dialkyl metal cariboxylates of lead carboxylates, d. H. clinging to the precipitation of lead chloride, they still have "15 the disadvantage that the carboxylic acid deposited will.

An object of the present invention is therefore to provide a method for stabilization of polymers and copolymers of vinyl chloride and those containing these polymers To create masses after which no opaque or cloudy products are obtained will. For this purpose, stabilizers are used according to the invention, which in the reaction disintegrate with hydrogen chloride into products, which in 'the polymers mentioned, copolymers or! compositions are soluble. The invention also aims at the production of stabilized masses or compositions from polymers and copolymers of vinyl chloride with improved electrical properties.

The process for stabilizing a polymer or copolymer of vinyl chloride or the mixtures or compositions prepared from them to prevent thermal decomposition, consists in that said polymer, copolymer or mixture is a trialkyltin monoalkoxy. compound is added whose alkyl radicals are chosen so that the 'corresponding trialkyltin chloride in the polymer or copolymer mentioned or in the polymer. containing Mixture is soluble. Preferably the alkyl radicals each contain not less than four Carbon atoms, and the alkyl radical of the alkoxy group contains from ii to 8 carbon atoms.

It has been found that the tributyltin monoalkoxides are particularly useful stabilizers and provide clear products. The invention Stabilizers can be added before, during or after the polymerization, but they are preferably added after the polymerization.

The effect of the organotin compounds used according to the invention appears to be that in the reaction with hydrogen chloride a double reaction takes place and on the one hand Trialkyltin chloride and, on the other hand, the aliphatic alcohol corresponding to the alkoxy radical will. For example, if tributyltin monobutoxide is used, tributyltin monochloride is used and normal butyl alcohol are formed, and these two compounds are in polyvinyl chloride -and in mixtures of polyvinyl chloride and in copolymers ■ of vinyl chloride and Mixtures of these soluble.

The trialkyltin monoalkoxides can be prepared by adding a trialkyltin monohalide is implemented with an .Alkalimetallalkoxyd. This reaction can be carried out by the trialkyltin halide added to a solution of the alkali metal alkoxide in the corresponding alcohol is, or by the dry powdered alkali metal alkoxide with an ethereal solution ■ of the trialkyltin halide is reacted. So z. B. Tributyltin monobutoxide produced are made by adding tributyltin chloride to a solution of sodium butoxide in butyl alcohol will; sodium chloride is precipitated and the tributyltin butoxide can then pass through Distilling the nitrated solution under reduced pressure can be obtained. The required Trialkyltin monohalide can be prepared by first following the usual Grignard reaction the alkylmagnesium halogen compound formed and then this with a solution of the the correct amount of the corresponding tin tetrahalide is reacted. The product however, this reaction usually consists of a mixture from which the pure trialkyltin halide can only be obtained with difficulty can, and therefore will the pure trialkyltin halide preferably made by a mixture of a tin tetraalkyl and a tin tetrahalide is heated in the proportions given by the equation:

3 R ₄ Sn + SnX ₄ h- 4 R ₃ SnX,

in which R is an alkyl group and X is chlorine, bromine or iodine.

The copolymers which are stabilized by the process of the present invention may include those made from vinyl chloride and other compounds with monoethylene bonds that have Vinyl chloride are polymerizable. These compounds include acrylonitriles; Acrylic acid ester, such as methyl acrylate, ethyl acrylate and the like; Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and the like; Esters of maleic and fumaric acid, such as dimethyl, diethyl, dibutyl, dihexyl or Dibenzyl ester; Esters of itaconic and aconitic acids; nc vinyl esters, such as vinyl acetate, vinyl chloroacetate, Vinyl methoxybutyrate and the like; Esters of glycol monoalkyl ethers, such as ethylene glycol monoalkyl ethers and vinylidene chloride.

The invention is illustrated in more detail by the following examples, which also show the advantages reveal the method according to the invention.

Example ι

There were three tubes each with a mixture of 2 g polyvinyl chloride and ίο ecm dibutyl phthalate filled. The first tube was given ο, .ΐ g of tributyltin methoxy and the second tube 0.1 g lead stearate added while the third tube was used as a comparative sample and no additive received.

All three tubes were placed in an oil bath and kept at a temperature of 180 to 185 ⁰ for 15 minutes. The tubes were then removed from the oil bath, cooled, and then examined for color and appearance. The first tube was pale yellow in color, showing very little degradation, but it was perfectly transparent. The second tube was whitish in color, but it was completely opaque, while the third tube with the comparison mixture was a strong dark red color but was transparent. The depth of color of the three samples of polyvinyl chloride is a measure of the thermal decomposition that has occurred, and the darker the color, the greater the decomposition. It can thus be seen that while the sample with the lead stearate was whitish and showed virtually no decomposition, the tube containing the tributyltin methoxy was slightly pale yellow, indicating that very little thermal decomposition had occurred compared to the comparative sample very severe decomposition had occurred in the absence of a stabilizer. The polyvinyl chloride tested in the present example was of relatively poor quality, i.e. it had a certain color and was not water-clear, and the color that occurred when tributyltin methoxide was used would have been even less if a purer sample of polyvinyl chloride was used for this test were.

Example 2

The following two mixtures were prepared: a) 100 g of polyvinyl chloride, 50 g of methyl glycol phthalate, 3.5 grams of tin stearate; b) 100 g of polyvinyl chloride, 50 g of methyl glycol phthalate, 3.5 g of tributyltin monobutoxide. Each of these mixtures was worked through on steam-heated rollers at 135 ° for 8 minutes. After that time was the mixture was completely homogenized and could be rolled out into a thin plate. the Plate a) was cloudy and opaque, while plate b) was completely translucent and was transparent.

At game 3

100 g of a copolymer of 95 parts by weight of vinyl chloride and 5 parts by weight of ethyl maleate were mixed with 20 g of tricresyl phosphate, 10 g of dibutyl phthalate and 5 g of tributyltin butoxide. This mixture was heated for 5 minutes on heated rollers to 135 to 140 °, and the processed mass was removed from the rollers as a 3 mm thick plate. This plate was then pressed for 3 minutes between polished plates at a temperature of 150 ^° and a pressure of 37.25 kg / cm ^2. The pressed plate, 2.5 mm thick, was so transparent that when held over a newspaper the print could be clearly seen and seen.

Was made from the same mixture but using 2.5 g lead stearate in place of the 5 g of tributyltin butoxide mentioned above made a plate of 2.5 mm, so this was so 'opaque, that the newspaper printing was through, the plate was not recognizable.

The tri-n-butyltin monobutoxide used was prepared by dissolving 9 parts by weight of clean sodium in 200 parts by weight of dry n-butyl alcohol and then quickly adding a solution of 108 parts by weight of tributyltin chloride in 100 parts by weight of dry n-butanol to the still warm solution of the sodium butoxide became. The mixture was stirred at room temperature for 1 hour and refluxed for an additional 40 minutes, after which it was cooled to room temperature and allowed to stand for 16 hours. The precipitated sodium chloride was removed by centrifugation, the clear supernatant liquid was decanted and the excess n-butanol was removed by heating under reduced pressure. By distilling the residue under reduced pressure, όο parts by weight of almost pure tributyltin monobutoxide were obtained; Boiling point at 3 mm Hg pressure 124 to 126 ° and refractive index η% 1.4685.

Example 4

1100 g of polyvinyl chloride were mixed with 50 g of dioctyl phthalate, 3 g of tributyltin monobutoxide and 0.125 g of stearic acid. This mixture was treated for 5 minutes at 140 ⁰ on rollers, and the plate was prepared a test piece having a thickness of 0.15 cm rolled at 150 ^0th It was then cut into seven pieces of 1.5 cm ^2, and six of these pieces were heated in an air oven to 175 ^0th The samples were removed from the oven after 5, 10, 15, 30, 45 and 60 minutes and compared with the unheated sample and with samples prepared in the same way in which the tiributyltin monobutoxide had been omitted.

The samples, which contained tributyltin monobutoxide, remained transparent and their color lay depending on the time of heating between colorless and slightly orange-brown.

The color of the samples that did not contain any stabilizer ranged from pale yellow to dark brown or black.

In each case, the samples that did not contain stabilizer were in color and in Transparency inferior to the corresponding samples containing tributyltin monobutoxide.

The tri-n-butyltin monobutoxide used was prepared by adding 6 parts by weight of pure sodium were dissolved in 250 parts by weight of dry n-butanol and the still warm solution of sodium butoxide a solution of 74 parts by weight of tributyltin bromide in 180 parts by weight of dry n-butanol was added dropwise over 15 minutes. Stirring was still going on. Continued at room temperature for 20 minutes and allowed to stand for 16 hours became. The precipitated sodium bromide was removed by centrifugation, the clear supernatant Liquid decanted and the üibeirschü'Sr

g n-fBufeanql. by heating under reduced _. Pressure removed. By distilling the residue under reduced pressure, 30 parts by weight became almost pure. Tributyltin monobutoxide obtained ;, Boiling point 124 to. r28 ° / 3rd mm Hg column; Refractive index «^ 1.4688 .;

.--- ·· example

.; A. manufactured as in the previous example Mixture,. however the / TrJbutyltinnmonobutoxyd by the same amount of tri-n-octyltin-mono-metal oxide was replaced was subjected to exactly the same treatment.

The samples obtained were in each case equivalent to the corresponding samples stabilized with tributyltin manobutocoxide and superior to the corresponding samples which did not contain any stabilizer.
The tri-n-octyltin monoxide was prepared by dissolving 3 parts by weight of pure sodium in 150 parts by weight of dry methanol and adding 41 parts by weight of tri-n-octyltin chloride to the still warm solution of sodium methoxydis. After the mixture was stirred for 5.5 hours at room temperature - it was allowed to stand for 3 days with the product "separating out as a methanol-insoluble liquid layer." The precipitated sodium chloride was separated by filtration and the excess methanol was removed by heating under reduced pressure. The paste-like residue was shaken with 150 parts by weight of water and the insoluble oil was extracted with light petroleum. The petroleum extract was washed with water and dried over anhydrous magnesium sulfate. After the solvent had been removed, the crude remained. Tri-n-octyltin monomethoxide as a soft and odorless liquid that is insoluble in water and alcohol. The crude product was distilled with slight decomposition under a pressure of 3 mm of mercury, "whereby 15 parts of a still slightly contaminated tri-n-octycin monomethoxide were obtained; refractive index η ^Z _D ° 1.4781.

Claims (1)

Patent claims. -i. Method for stabilizing polymeric Mixtures containing vinyl chloride against thermal decomposition, characterized in that that the mixture mentioned a trialkyltin monoalkoxide is added, its the corresponding trialkyltin chloride is soluble in the polymer mixture, 12. The method according to claim α, characterized in that that the alkyl radicals of the trialkyltin alkoxide each have at least four carbon atoms urtd the alkyl radical of the alkoxy group of the trialkyltin monoalkoxide 1 to 8 carbon atoms contain. 3. The method according to claim 1 and 2, characterized in that the trialkyltin monaalkoxide is added to the polymeric mixture after the polymerization of the vinyl chloride. 4. The method according to claim 1 to 3, characterized characterized in that one of the decomposition products of said trialkyltin monoalkoxide is removed by volatilization during subsequent processing under heat. Referred publications:
U.S. Patent No. 2,267 5615 12.