DE2039494C3 - Process for the production of polyisoprene - Google Patents

Description

Polyisoprene is generally made by solution polymerization of isoprene in an organic solvent (e.g. a hydrocarbon) with organometallic Mixed catalysts (Ziegler catalysts) produced. This polymerization gives mostly K- to 20 '? ige polyisoprene solutions which initially still contain the active catalyst. To the To obtain the solid polyisoprene, the catalyst is first deactivated. the polymer is stabilized and then removing the organic solvent. This is usually done by steam distillation of the organic solution (“stripping”) and subsequent drying of the polymer.

The organometallic catalysts used for the polymerization, for example combinations of salts of metals from group IV. V. VI and VIII of the periodic table with organometallic compounds from groups I., II and III of the periodic table, are almost always chlorine-containing because the preferred metal salts are the chlorides (ζ. Β. I ιί I ₁ ). When the polyisoprene solution is worked up, considerable amounts of chlorine remain in the polyisoprene, usually around ppm. back, which adversely affect the properties of the polymer. This is particularly true when the Dcsaklivicrung diamines or polyamines (gem.iU British Patent Specification 1 77 I ¹ W)) uses the lOlvimnsaleigcnsdiaftcn, in particular the Wärniesiabilitätj are thin but Gul _t 'of the Chiüfidgehält is very high. It is also known from OE-AS 1 2580% to add dispersants of the type described during the coagulation process, ie during the steam distillation. This procedure gives a product with a very high chlorine content.

Mali also has selion the catalysts in l'ölydiene solutions deactivated with aqueous metal hydroxide solutions. Then products with a low value emerged Chloride content, but their properties, especially their thermal stability, are very unsatisfactory. > The object of the present invention is to provide a method with which one from catalyst-containing Polyisoprene solutions can isolate a polyisoprene that has a low chloride content and at the same time perfect polymer properties. The removal of the chloride from the polymer is necessary because it interferes with the further processing of the rubber, especially metallic further processing devices attacks.

The invention relates to a process for the isolation of polyisoprene from its catalyst-containing solutions which contain chlorine in organic solvents
1) Deactivation of the catalyst by means of a

aliphatic di- and / or polyamine and
- ¹ Ii 2) subsequent conversion of the organic Polynicrisatlüsung by means of a dispersant into an emulsion and subsequent
3) Coagulation of the emulsion without separation of the

Water by steam distillation,
. · "> Characterized in that after deactivation and before coagulation, the organic polymer solution with water in the presence of a water-soluble alkali, alkaline earth or earth metal salt of water-soluble polymeric compounds containing COOH groups,

as a dispersant, in a oil-in-water emulsion is converted, the conversion being carried out at a temperature at which does not yet coagulate Γι of the polymer during emulsification.

For the success of the procedure it is necessary to follow the individual steps in the order given to execute.

All solutions of poly-isoprene in organic solvents, such as those obtained in conventional solution polymerization with mixed organometallic catalysts, are suitable for the process. In particular, these are H to 20% solutions in hydrocarbons or chlorinated hydrocarbons such as benzene. Chlorobenzene. Toluene. Hexane.

Suitable aliphatic di- or polyamines for deactivating the catalyst are e.g. Ii. Alkylenediamine such as alhylenediamine. Propylenediamine, 1,4-diaininohulane. retramethylethylenedianiine and N-methylpropylpropylamine and alkylenepolyamine such as diethyltriamine. Dipropyleniriamin and fetraathylenpentamin Their amount is between (1.01 and 1.0 weight per cent, preferably 0.02 to 0.5 weight per weight, based on synthetic rubber.

To convert the polymer solution into an emulsion, the solution is mixed intensively with water in amounts of about 1 to .10 (1 wt .- '/. Preferably 1 to 70 Cicw .-' /. Based on the polymer solution. This water Dispersants, preferably particularly water-soluble alkali, alkaline earth or earth metal salts of water-soluble polymeric compounds which contain GÖÖH groups are used. Copolymers of isobutylene and maleic anhydride which have been saponified with alkali hydroxides, for example sodium hydroxide, are particularly preferred This dispersant may be added with water generally in amounts of I to 1 () _{t is} preferably 3 to 7 wt .-%. the Hersel averaging of the emulsion is generally ini

at room temperature. It is possible to use slightly higher temperatures, only when Emulsifying the polymer will not be precipitated.

The emulsion obtained in this way can be used directly without separating off the water in the customary manner by steam distillation be coagulated.

If these measures are observed, a polyisoprene with good heat resistance, light color and low chlorine content (below 450 ppm).

Example I.

In a continuous process using a TiClj / AIRj catalyst became polyisoprene solution (solids content 8 to 10%) stopped in a continuous mixer by adding 0.19% ethylenediamine. At the same time, 0.5% Di-tert-butyl-p-cresol and 0.4% N-methylstearylamine admitted. In a second mixer, 70% water (based on the polymer solution) was added, which 0.02% cijes copolymers of maleic anhydride and isobutylene hydrolyzed by means of NaOH contained as a dispersant. A stable emulsion was obtained which did not have the water separated off was coagulated by means of steam. After drying, the rubber contained 0.026% chlorine ions. During storage in heat (14 days at 70 ° C.) the ML-4 'value was reduced by only 10 units.

Comparative example A

Analogous to Example I, but omitting the dispersant, a product was obtained which still contained 0.09% chlorine ions. The ML-4 'was

by 56 units

after 14 days of storage at 70 '
lower than at the beginning.

Comparative example B

A rubber was produced analogously to Example 1, but with the addition of the dispersant in the coagulator with unchanged high chlorine content (0.1%) found. After 14 days of storage at 70 ° C., the Mooney value fell (ML-4 ') by 51 units.

Example 2

In a continuous mixer, the polyisoprene solution was stopped by adding 0.25% propylenediamine. A mixture of 0.5% di-tert-butyl-p-cresol was successively mixed in a second mixer and 0.4% N-methylstearylamine in hexane and 15% water (based on rubber cement), which 0.1% of a copolymer of maleic anhydride dissolved with diisobutylene was metered in. To When the emulsion emerged from the mixer, it was coagulated with hot water. The dried one colorless product contained 0.023% chlorine ions and showed after storage in heat for 14 days 70 ° C a lowering of the original M1.4 'value (88) by 9 units.

Example 3

A rubber was made analogously to Example 1, but omitting the addition of N-methylstearylamine obtained with a chlorine ion content of 0.025%. During the 14-day heat storage one occurred ML-4 'depression of only 11 units.

Claims (1)

3) Claim: Process for the isolation of polyisoprene from its catalyst-containing solutions containing chlorine contained, in organic solvents by 1) deactivation of the catalyst by means of a aliphatic di- and / or polyamine and subsequent conversion of the organic Polymer solution into an emulsion by means of a dispersant and subsequent coagulation of the emulsion without separation of the water by steam distillation, characterized in that after the deactivation and before the coagulation organic polymer solution with water in the presence of a water-soluble alkali, Alkaline earth or earth metal salt of water-soluble polymeric compounds containing COOH groups as a dispersant, converted into an OI-in-Wüa ^ erertiuNion is, the conversion being carried out at a temperature at which, during emulsification, there is still no coagulation of the Polymer occurs.