DE1295812B - Process for the production of gel-free solutions of diene polymers - Google Patents

Description

It is known that anhydrous polymer solutions can be obtained from the process according to the invention

water-containing polymers in such a way. /. The dispersions of the diene / polymerizates are expedient make sure that the water-containing polymers in with an excess of polymerizable äthylemit Water azeotropically distillable solvents, nically unsaturated compounds such as styrene, a-Mez. B. aromatic hydrocarbons, and the 5 thylstyrene and butyl acrylate, optionally Water in the form of the azeotropic mixture with a also mixed with other solvents before part of the solvent by distillation from the added solution in a weight ratio of 1: 1 to about 1:40 removed. However, this procedure has more. Berries are used as additional solvents Disadvantage. For example, an azeotropic distillation is always aliphatic, cycloaliphatic or aromatic a temperature load of the in the Lö- io matic hydrocarbons, ethers, esters, ketones Solution contained polymer connected what is or halogenated liquid hydrocarbons in Bebei sensitive polymers, such as polytracht. , Cyclohexanone, benzene, serve, or even if the solvent is xylene, ethylbenzene and toluene, is itself a monomer, in the formation of It is advantageous to use the diene polymer dispersions

crosslinked and gel-like particles are disadvantageously noticeable before or after being combined with the solution power. Furthermore, after the medium has been circled, there is still precipitant to destroy the dispersing water from the solution in general to add a filtration sion, z. B. Electrolytes, such as diluted the remaining solution is essential to prevent sulfuric acid, calcium chloride, aluminum sulfate or existing suspended matter, e.g. B. catalyst residues or sodium chloride. The precipitated polymer is then Boiler contamination, to be removed from the solution- ao immediately dissolved from the organic liquid, run. It is often expedient to additionally use phase separation agents

It is from US Pat. No. 2,888,498 in amounts of 0.001 to 0.5 percent by weight knows, from aqueous diene polymer dispersions rapid separation of the water-containing systems into the add the diene polymers by adding precipitated aqueous and organic phases. Suitable agents to be deposited as an oil gel layer and these oily phase separation agents are, for example, polyethers, such as Layer then after it has been separated from the aqueous polypropylene or polyethylene glycols, with a molecular phase in solvents such as methylcyclohexane and weights between 500 and 2000. Take up benzene and the solutions by addition. According to the invention, the water-containing systems are

of desiccant to dry. This method is available in amounts from 0.05 to. 20%, in particular 0.05, however, very expensive. In addition, it is known from the 30 to 0.5% ^{sedimentation USA patent specification 2 739 954, which is} customary in its weight, that a solution is added as an aid. Examples of suitable sediments of a butadiene-styrene copolymer in toluene tation auxiliaries are finely divided inorganic substances to be prepared by removing residual monomers from insoluble substances such as kaolin, zinc oxide, titanium-containing polymer paste with a solids content of dioxide, aluminum oxide, chalk or Ba-62% with the addition of larger amounts Albumin with 35 rium sulfate. The toluene treated is particularly suitable here. The effectiveness of this method of adding calcium hydroxide and / or silica gel, however, leaves something to be desired, and it prepares great The separation of the water and that in the solution

Difficulties, technically reproducible results of undissolved constituents, such as the catalyst residues, the to obtain. Finally, this is also from the British boiler contaminants, as well as the inorganic ones Patent specification 828 650 known process for the precipitation agent and sedimentation aid takes place provision of solutions, for example the polybuta- afterwards with the help of a customary separator at Raumdiens, in styrene not satisfactory, since you then temperature, z. B. with a slingshot or better with cloudy solutions containing only crosslinked gels a continuously operating separator, receives. This way of working not only makes it possible

It has now been found that gel-free solutions 45 in a continuous procedure from dispersions of of diene polymers with water contents among diene polymers without the detour of precipitation 0.1% from aqueous dispersions of the polymers and the other work-up directly polymer especially can be produced advantageously if one produces in solutions with water contents below 0.1%, the dispersions solvent, which only but it is achieved at the same time that by the or partially from polymerizable unsaturated 50 works under mild conditions, d. H. prak connections consist, emulsified, the water-containing table at room temperature, any stress of the System with 0.05 to 20% of its weight of inorganic polymers, which have the disadvantages mentioned above Ganischen sedimentation aids added and brings, is avoided.

Water and undissolved constituents with the help of a The process is therefore particularly suitable for

Separators at room temperature in a known 55 production of solutions of rubbery Way. Diene polymers in polymerizable ethylenic

For the process as a starting material in unsaturated compounds in the manufacture of Aqueous dispersions of the diene impact-resistant polymers in question.

Polymers generally have dry contents. The parts mentioned in the examples are so far

between 5 and 60 percent by weight and may not be otherwise noted 60 parts by weight. The indicated immediately and gently in practically anhydrous percentages relate to the weight. Polymer solutions are transferred. Suitable . -I ₁

are especially the commercially available polymers in Example 1

Based on butadiene or isoprene, the homopoly 100 parts of an 18.6% aqueous polybutadiene

Merisates or copolymers with other mono-dispersions were made with 150 parts of styrene, 50 parts mers, such as acrylic esters, styrene, vinyl esters, vinyl n-butyl acrylic acid, 10 parts of acrylonitrile and ether, z. B. n-butyl acrylate, 2-ethylhexyl acrylate, VI 40 parts of ethylbenzene and 10 parts of china clay nyl acetate or vinyl propionate, may be present. and 15 parts of a 20% aqueous phosphoric acid

solution added and stirred. After the phase separation, most of the separated water was peeled off and the polymer solution forming the upper layer to a Westfalia separator type LHG 205, supplied and freed from solid impurities, the auxiliary materials and the remaining water. A clear, gel-free solution with a solids content of about 6.5% was obtained, the water content of which was below 0.1.

Example 2

IO

100 parts of a 20.5% aqueous polyisoprene dispersion were mixed with 200 parts of a-methylstyrene, 50 parts of acrylonitrile, 50 parts of xylene, 0.5 part of 2,6-di-tert-butyl-p-cresol and 10 parts of a 25% aqueous phosphoric acid solution and stirred. After the phase separation, 10% aluminum oxide became metered in, based on the water-containing polymer solution forming the upper layer, and the polymer solution continuously in an ao separator with self-cleaning drum, type SAOH 205 from Westfalia Separator, Oelde, separated from solid impurities and the remaining water. A clear gel-free polymer solution with a solids content of about 6.1% was obtained, whose water content was below 0.1%.

Example 3

100 parts of a 23% strength aqueous dispersion of a polymer composed of 85% butadiene, 10% styrene and 5% vinyl methyl ketone with 100 parts of toluene, 200 parts of styrene and 5 parts of aluminum sulfate and 0.5 part of polyethylene glycol (molecular weight 2500 to 5000) as a phase separating agent and 10 parts a 15% aqueous hydrochloric acid was added and the mixture was stirred. After the phase separation, the under aqueous phase (about 60 parts) drawn off. The upper organic phase (aqueous polymer solution) 2 parts of titanium dioxide were added and fed continuously into a Sharpless separator. the end the separator was discharged a clear, gel-free polymer solution, the solids content of which was 7% and the water content of which was less than 0.05%.

Example 4

100 parts of a 10% polybutadiene dispersion were mixed with 1 part of polypropylene glycol, 250 parts Styrene, 10 parts of a 10% strength aqueous sodium chloride solution and 5 parts of 1% strength aqueous sulfuric acid added and stirred. After the phase separation, most of the deposited was Water (about 50 parts) drawn off, then 3 parts of kaolin added and the cloudy solution continuously fed to a separator and there from solid impurities, the auxiliary materials and the rest Frees water. A clear solution with a solids content of about 4% was obtained Water content below 0.1%

Claims (2)

Patent claims: 1. Process for the preparation of gel-free solutions of diene polymers with water contents below 0.1% from aqueous dispersions of the polymers, characterized in that one in the dispersions solvents that consist exclusively or partially of polymerizable ethylenic unsaturated compounds exist, emulsified, the water-containing system with 0.05 to 20% its weight in inorganic sedimentation agents and water and undissolved components separated with the aid of a separator at room temperature in a manner known per se. 2. The method according to claim 1, characterized in that the water-containing systems Adding precipitant to destroy dispersions and / or phase separating agents.