A method of inhibiting the polymerization of vinyl chloride

 

(57) Abstract:

Usage: inhibition of polymerization of vinyl chloride in the process of its synthesis and distillation. The inventive as inhibitor use nN-bis-/3,5-di-tert-butyl-4-oxybenzyl/piperazine in the amount of 0.025 to 0.2% by weight of vinyl chloride. table 1.

The invention relates to the field of macromolecular chemistry, more specifically to methods for inhibiting the polymerization of vinyl chloride. The problem is particularly relevant in industrial scale for the synthesis of a monomer and its rectification, because in these conditions, there is the formation of polymer, collecting pipes, showerheads, and a plate distillation columns, as well as tube boilers, which reduces the length of the run of the columns.

You know the introduction of the polymerization recipe inhibitors 2,2-methylene or 2,2-ethylidene-bis(4,6-di-tert - butylphenol) [1]

The closest in technical essence to the present invention is a method of inhibiting the polymerization of vinyl chloride in the process of rectification and storage in the presence of inhibitors, representing aromatic oxycoedone type phenol or its alkalinuria, when in the reaction mixture are the real initiators (percarbonate, Monomeric or polymeric peroxide vinyl chloride).

The aim of the invention is to increase the efficiency of inhibition of polymerization in the synthesis and distillation of vinyl chloride (I).

This goal is achieved using the inhibitor N,Nlbis-(3,5-di-tert-butyl-4-oxybenzyl)piperazine (BP), taken in an amount of 0.025 to 0.2 wt. from REF. The product under THE 6-22-166-87 and has the structural formula:

HO - CH2- NN CH2-

N, Nlbis-(3,5-di-tert-butyl-4-oksijen - ZIL)piperazine is a white powder with a melting point 212about(Mass fraction of the basic substance is 97% mass fraction of water and volatile substances 0,5%).

P R I m e R 1-5. In spetsstalej autoclave (4 liters) equipped with a jacket for maintaining the desired temperature and stirrer, load 1550 g of the aqueous phase (0,15% solution of methyl hydroxypropyl in water), consisting of 0.09 g of caustic soda and 0,0089 g of diphenylolpropane; 2.9 g of the initiator di-2-ethylhexylcarbonate and 800 g of vinyl chloride. In the curing composition of the formulation is administered inhibitor of BP in the number 0,025; 0,05; 0,075; 0,1; 0,2% by weight of mono the first change of the amount of pressure from the initial appointment, the duration of polymerization and polymer yield.

The results are presented in the table and show that with increasing concentration of the inhibitor is observed the decrease of the magnitude of R, the increase in time of polymerization and reduction of output PVC. The highest efficiency of product BP is manifested at a concentration of 0.1% by weight of vinyl chloride.

P R I m e R 6 (for comparison). Similar to examples 1-5, but without the introduction of inhibitor. In this case, there is a significant pressure drop, the polymerization ends quickly enough for 6 h, and the polymer yield is at the level of conventional suspension process. The data given in the table.

P R I m e R s 7-9 (for comparison). Similar to examples 1-5, but as inhibitors used respectively hydroquinone (0.1% of I) and BHT (0.1 and 0.4% of BX). The results are shown in the table. It should be noted that the sum of the indicators introduction hydroquinone almost identical to the control sample (example 6). BHT is a more effective inhibitor than hydroquinone, but much inferior to the proposed BP product even in the case of a fourfold increase in concentration (comparison of examples I, as inhibitor use N, N-bis-(3,5-di-tert-butyl-4-oxybenzyl)piperazine in the amount of 0.025 to 0.2% by weight of vinyl chloride.

 

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1 tbl

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3 cl, 2 tbl

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10 ex, 1 tbl

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1 dwg, 6 ex

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8 cl, 2 tbl

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5 cl, 1 tbl, 1 ex

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2 cl, 5 tbl, 1 dwg, 21 ex

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5 cl, 2 tbl

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1 tbl

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