FI58646B - REFRIGERATED FOUNDATION OF VINYL CHLORIDE BASED POLYMERS AND COPOLYMERS - Google Patents

Description

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Patent- och rcglftarttyrelaan Antöian uttagd och uti. * Krifi * n pubticarad 28.11.80 (32) (33) (31) Pyy ^ «« y etuelkew — Begird prlorhet l6.02.73

France-France (FR) 7305537 (71) Rhöne-Progil, 25, Quai Paul Doumer, F-92 ^ 08 Courbevoie, France

Francrike (FR) (72) Francis Foumel, Chauny, Salosien Soussan, St-Fons, France-Frankrike (FR) (7M Berggren Oy Ab (5U) Process for the mass production of vinyl chloride-based polymers and copolymers 62) By dividing separated from the application 1 + 13/7 ^ (patent 57 ^ 26) -Avdelad fr & n trap 1 + 13/7 ^ (patent 57 ^ + 26)

The present invention relates to a process for the mass production of vinyl chloride-based polymers and copolymers.

It is known that in the past it has been proposed to carry out the mass production of vinyl chloride-based polymers and copolymers in two steps in different equipment, by a method of limited polymerization in the first step, called the prepolymerization step, with vigorous vortexing until the monomers are converted to %, and then in the second step the final polymerization is carried out at a low agitation rate, which, however, is sufficient to ensure that the good temperature of the reaction mixture is equalized until the completion of the polymerization or copolymerization reaction.

This method and its application variants are described in detail in French Patent 1,382,072, Produits Chimiques PSchiney-Saint-Gobain, and in its supplementary patents 84,958, 84,965, 84,966, 85,672, 89,025 and French Patents No. 5,866. 6 436 744 and its supplementary patents 87 620, 87 623, 87 625, 87 626.

According to one embodiment of the method, the final polymerization delivery is carried out in an upright autoclave equipped with a stirrer comprising a single stirrer consisting of at least one helically wound strip attached by at least one support to a rotating shaft which inserts the autoclave into its center line at least one branch is attached to the lower end, which follows the shape of the curved bottom of the autoclave.

The process according to the invention, according to which the final polymerization is also carried out in an upright autoclave, has the following surprising advantages over the prior art: - reduction of deposits and precipitate formation on the autoclave walls, - higher efficiency of polymerization initiators, making it possible to reduce polymerization the amount of substances expressed as active oxygen and thus to obtain polymers and copolymers which have better properties and in particular greater homogeneity and a denser grain composition and which can be used to obtain products which are weakly colored.

According to the process of the invention, in the first step, called the prepolymerization step, limited polymerization is carried out with vigorous vortexing until the conversion of the monomer or monomers is 7-15%, and then in a second step, in a substantially upright autoclave, the final polymerization is carried out at low agitation. to ensure good thermostatization of the reaction mixture until the completion of the polymerization or copolymerization reaction.

According to the method of the invention, at least one agitation zone is formed in the autoclave around a vertical axis by means of an agitator comprising an agitator A consisting of a helically wound strip fixed to a rotating shaft which simultaneously injects and rotates through the top of the autoclave independently a second agitation zone in the lower part of the autoclave by means of agitator B, the use of which is independent of the use of agitator or dampers A, consisting of at least one branch conforming to the curved bottom of the autoclave and fixed through the center of the autoclave.

Mixer B usually comprises two branches. Agitators A and B may be hollow so that a heat exchange medium can be recycled therein.

According to an embodiment of the invention, the agitation zones formed by the agitator A and the agitator B, respectively, are concentric.

According to another embodiment of the invention1, the agitation zones formed by the agitators A are equidistant from the center line of the autoclave and are generally evenly distributed around the center line. Thus, if there are, for example, three agitation zones formed by the agitators A, they are equidistant from the center line and are located at the vertices of an equilateral triangle. This embodiment is particularly advantageous in the case of a high-volume autoclave, since it avoids recourse to an unreasonably large drive, which requires a special structure.

In the following, two embodiments of an autoclave with which the method according to the invention is carried out will be described by way of example in connection with the accompanying drawing.

Figures 1 and 2 are vertical sectional views along the centerline of the autoclave.

Figures 3 and 4 are horizontal sectional views taken along lines III-III of Figs. From IV to IV.

In Figures 1 and 3, the agitator comprises only one agitator A.

4,58646

In Figures 2 and 4, the agitator comprises three agitators A.

The vertical axial autoclave 1 is surrounded by a jacket 2, inside which a heat exchange medium is circulated, which enters through the pipe joint 3 and exits through the pipe joint 4. At the top of the autoclave 1 there is a pipe connection 5 for loading the prepolymer, the necessary reagents and any monomers and a pipe connection 6 for removing the unreacted monomer mixture at the end of the operating step. At the bottom of the autoclave 1 there is a pipe connection 7 for removing the polymer.

A rotating shaft 9, to which two arms 10 are attached and which is supported by a bearing 11, is inserted through the base 8 of the autoclave 1; the rotating shaft is sealed to the bottom of the autoclave with a sleeve seal 12.

In Figures 1 and 3, a shaft 13 rotating along the center line of the autoclave, supported by a bearing 14, is inserted through the upper part of the autoclave 1; the rotating shaft is sealed relative to the top of the autoclave by a sleeve seal 15. This rotating shaft has a strip 16 threaded into helical threads.

In Figures 2 and 4, three rotating shafts 17, 18 and 19 are inserted through the upper part of the autoclave 1 at equal distances from the center line of the autoclave, placed at the tips of an equilateral triangle and supported by bearings 20, 21 and 22; these rotating shafts are sealed relative to the top of the autoclave by sleeve seals 23, 24 and 25. For the rotating shafts 17, 18 and 19, strips 26, 27 and the like are threaded into helical threads. 28.

With the method according to the invention, it is possible to carry out the best possible mixing by selecting the appropriate agitation intensity and direction for each mixing zone.

Claims (1)

A process for the mass production of vinyl chloride-based polymers and copolymers in two steps carried out in a certain apparatus, which process comprises carrying out limited polymerization in a first step, called a prepolymerization step, with vigorous vortexing until 7% conversion of monomer or monomers in a second step in a substantially upright autoclave, final polymerization at a low agitation rate, which, however, is sufficient to ensure good heat equilibration of the reaction mixture until the completion of the polymerization or copolymerization reaction, characterized in that at least one agitation zone A is formed in the autoclave. a screw-threaded strip attached to a rotating shaft which pierces through the top of the autoclave and rotates about a vertical axis, j a simultaneously and independently forming a second agitation zone in the lower part of the autoclave by means of agitator B, the use of which is independent of agitator or agitators A and consisting of at least one branch conforming to the curved base of the autoclave and fixed to the center of the autoclave.