CS259282B1 - The method of determination, and the stability of the emulsion system of polymers and copolymers - Google Patents

Abstract

The stability of an emulsion polymer system formed by emulsion polymerization or copolymerization of acrylates and/or methacrylates is determined by measuring the conductivity of the emulsion. The stability limit is defined by a sudden increase in conductivity.

Description

The invention relates to a method for determining the stability of an emulsion system of polymers and co-polymers.

The mixed emulsifying system is not used to synthesize polymers and copolymers. These mixed emulsifying systems consist of emulsifiers of the given homologous series, but in some cases mixtures of emulsifiers of the rhode type have also been found suitable [M. S. El-Aasser, T. Makga-winata, J. W. Vanderhoff, C. Pichot: Prepr. Coatings Plastics Chem. 42, 44 (1980)] Low-emulsifier polymer latexes are required for utility properties, since high concentrations of post-active ingredients enhance the hydrophilic character of the low-adhesion polymer films and the inferior physical properties. In other words, the physical properties of the polymer films and the stability of the polymeric ethers are a function of the concentration and the type of emulsifier used (JW Vanderhoff: J.Polym. Sci. Polym. Symp. 72, 161 (1985)] The stability of the polymer and copolymer emulsions is determined by measurement Flocculating agents sensitize the flocculation of the latex particles, their aggregation, and settling. In addition, the addition of a coagulating agent degrades the emulsion and hence its further use [T. Makawinata, MS El-Aasser, JW Vanderhoff, C. Pichot: Acta Polymeric 32, 583 (1981)].

The above drawbacks are substantially obviated by the method of determining the stability of the emulsion polymer and copolymer system, wherein the conductivity of the emulsions is measured and the stability of the emulsion is determined by a sudden increase in the conductivity of the emulsion system. An advantage of the proposed method of determining the emulsion system of polymers and copolymers is that the determination is simpler, less laborious, more economical, and allows the stability of the polymeric dispersants during the polymerization process to be monitored. Example 1

150 ml of distilled water (20 g) are metered into a three-necked 500 ml reaction flask equipped with a stirrer, a back-cooler, a nitrogen inlet, a preconditioned latex sampling device and a conductive electrode (OK 902). methyl methacrylate, 80 gethyl acrylate, 4.5 g 97% wt. aqueous solution of monopalmitate polyoxyethylene sorbital (Tween 40), 0.5 g of a 40% aqueous solution of sodium α-octadecenyl sulfate (Part AOS). After stirring for 30 minutes (400 ° C per minute), 0.25 g of ammonium persulfate (initiator) is added at 60 ° C. During the copolymerization, 10 mllatex is taken to isolate the copolymer, the amount of coagulate, and the degree of conversion. The emulsifier, initiator and unreacted mono- mers are removed from the latex by dialysis using a dialysis tube. The purified copolymer latex is coagulated in methanol acidified with hydrochloric acid to pH = 2 and the copolymer obtained by coagulation is washed with water, dried at 60 ° C for 8 hours. From the thus obtained data on the amount of the resulting copolymer, the conversion value is obtained [I. Čapek, J. Bartoň, E. Orolínová: Chem. Rumors 38, 803 (1984)]. By filtering a sample of the latex, the amount of coagulum in the reaction system was obtained. For a 10% conversion, the conductivity of the solution was 0.5 mS. cm-1 with 0.0 g of coagulated co-polymer. Example 2

The procedure is as in Example 1, except that the conductivity of the latex is measured and the amount of coagulum is determined at 40% conversion. The conductivity of the copolymer latex is 0.5 mS. cm-1 and the latex contains 0.0 g of coagulated copolymer. Example 3

The procedure is as in Example 1, except that the conductivity of the latex is measured and the amount of coagulum is fixed at a 45% conversion. The conductivity of the copolymer latex is 0.6 mS. cm-1 and the latex contains 0.1 g of coagulated copolymer. The data indicate the interstability of the copolymer latex. Example 4

The procedure is as in Example 1, with the exception that the conductivity of the latex is measured and the amount of coagulum is fixed at 60%. The latex conductivity is 1.3 mS. cm '1 alatex contains 1.0 g of coagulated copolymer. Example 5

The procedure is as in Example 1, except that the conductivity of the latex is measured and the amount of coagulum is fixed at 80% conversion. The latex conductivity is 2.0 mS. 1 and 1a-tex contains 2.0 g of the coagulated copolymer. Example 6

The procedure is as in Example 1, except that the conductivity of the latex is measured and the amount of coagulum determined at 30% by weight.

Claims (1)

SUBJECT Method for determining the stability of an emulsion system of polymers and copolymers resulting from emulsion polymerization or copomerization of acrylates and / or methacrylates, characterized in that the conductivity of the emulsion is measured and the emulsion stability limit is determined by suddenly increasing the conductivity of the emulsion system.