FR2495622A1 - PROCESS FOR POLYMERIZING ETHYLENICALLY UNSATURATED MONOMERS AND CATALYTIC SYSTEM USED THEREFOR - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF POLYMERS AND COPOLYMERS OF ETHYLENICALLY UNSATURATED MONOMERS, IN PARTICULAR VINYL CHLORIDE. THE POLYMERIZATION IN MASS OR IN SUSPENSION OF SUCH MONOMERS IS DONE IN THE PRESENCE OF A CATALYTIC SYSTEM CONTAINING T-AMYL PEROXYPIVALATE AS AN INITIATOR.

Description

The present invention relates, in general, to a process

polymrrisation

  various ethylenically unsaturated monomers, in particular

  vinyl chloride, in bulk or suspension systems, using t-amyl peroxypivalate as the initiator, the invention also encompassing

  catalytic systems comprising this peroxypivalate.

  Vinyl chloride suspension polymerization is generally carried out at temperatures below 70 ° C using organic soluble initiators. Although lauroyl peroxide was previously the most widely used catalyst,

  we started to use fluently in the course of

  years, other catalysts for low tempera-

  including azo-bis-isobutyronitrile, diisopropyl peroxydicarbonate, peroxypivalate

  t-butyl and mixtures thereof.

  The choice of the initiator requires consideration of the nature of the catalyst and its influence on the polymerization process, as well as the properties of the polyvinyl chloride that is produced.

  The polymerization of vinyl chloride is

  characterized by a short priming period, followed by

  a gradually increasing rate of polymerization. Of-

  In the preliminary stages of the polymerization, the reaction rate is below the maximum speed so that the capacity of the reactor is not fully utilized. An appropriate initiator must reduce this

  start-up period and, because of a more

  polymerization aunt, it increases the productivity of the reactor. In addition, an appropriate initiator will be the one

  which can be used, in general, in terms of

  relatively weak tones giving a weak

  branching during polymerization

  Although some peroxyes-zers, c = _w_ the

  diisopropyl peroxydicarbonate, are known to

  While offering me some advantages during the vinyl chloride cure, their disadvantage is however a long time to initiate a non-uniform polymerization speed, the need for a low transport.

  temperature and the decrease in yield at tem-

  high levels. The development of an offering initiator

  the known advantages without the disadvantages

  are normally an important issue

  in the field of the polymerisation of chloride of

nyle.

  An object of the present invention is accordingly

  how to provide a polymerization process from mcno & -

  ethylenically unsaturated resins, er. particular chlorine

  re vinyl, in the presence of a compound perozyDîné aui is not subject to the disadvantage known initiators

  traditional peroxides, at temperatures below

  the peroxide is stable and easily handled. Another object of the present invention is to provide a method for bulk polymerization or

  suspension of vinyl chloride at tm = - =

  less than 70 ° C., using a suitable peroxy-gn compound, as initiator

  It has now been found that such an improvement

  in the polymerization of unsaturated monomers, in particular vinyl chloride, can be

  by employing t-amyl peroxypivalate as an initial

tor.

  According to the present invention, the polymer

  of ethylenically unsaturated monomers, in particular

  vinyl chloride, is carried out in bulk or in suspension, under the conditions which are applicable to them and which are well known to specialists,

  using a catalytic system comprising

  t-amyl xypivalate as initiator. Although it has been found that the use of t-amyl peroxypivalate

  only as initiator gives very satisfactory results.

  it can be used at the same time as other well known initiators or modifiers, and this

desires.

  It has been found that the use of peroxypi

  t-amyl valate gives equally satisfactory results in mass or suspension polymerizations of

  ethylenically unsaturated monomers.

  In general, we will use peroxygen

  t-amyl pivalate in a concentration of about 0.01

  to about 5.0% by weight of the vinyl monomer, the

  preferred concentration within the range of

from about 0.05 to about 1.0% by weight.

  The processes normally used in the

  lymerization by mass or suspension of

  vinyl are applicable in the case of the process of the in-

  vention. Typical methods have been described in "Encyclopedia of Polymer Science and Technology", 14

339-343 (1971).

  The polymerization can be carried out under pressure

  atmospheric pressure or at a higher pressure. In the

  usual process, the reactor is charged to the pressure

  mospheric and the pressure rises when the content

  of this reactor is brought to the reaction temperature.

  The pressure can increase further because of the character

  exothermic reaction and then remains

  aunt until the conversion reaches about%, then decreases rapidly as

the reaction continues.

  The polymerization temperature can range from -501C to + 700C for bulk polymerization, although temperatures of 40 to 600C are preferred. The polymerization can be carried out in suspension at

  temperatures from + 51C to + 70WC, although the temperatures

  Preferred amounts are of the order of 20 to 600 ° C.

  The concentrations of the monomer and water, for example at a weight ratio of about 2: 1, and the types and concentrations of suspending agents are those normally expected in suspension polymerization and which are well known to specialists. Typical suspending agents are polyvinyl alcohol, partially saponified polyvinyl acetate, gelatin, methyl cellulose, a vinyl acetate copolymer and the like.

  of maleic anhydride, etc. we can add various emul-

  such as sulfonated oils and ethylene oxide condensates to control surface tension and particle shape. Buffers may also be used as needed, for example when gelatin is used as a suspending agent. agents can be used

  chain transfer, such as chlorinated hydrocarbons

  res and isobutylene, in the preparation of poly-

mothers of low molecular weight.

  Although the peroxygen initiator of the pre-

  This invention is of particular interest in the bulk polymerization or suspension of chloride

  vinyl, it can also be used in the copoly-

  merit of vinyl chloride with chloride of

  vinylidene, vinyl acetate and other monomers.

  res undergoing copolymerization with chloride

of vinyl.

  Homopolymerization and copolymerization of other ethylenically unsaturated monomers can be accomplished with the peroxygen initiator of the present invention. Examples of monomers are ethylene, vinylidene chloride, styrene, vinyltoluene,

  α-methylstyrene, p-chlorostyrene, p-chloromethyl

  thylstyrene, butadiene, isoprene, piperylene, chloroprene, vinyl acetate, vinyl propionate, vinyl benzoate, acrylic and methacrylic esters, especially methyl acrylate, ethyl acrylate , butyl acrylate, acrylate

  2-ethylhexyl, lauryl acrylate, methacrylate,

  methyl lattice, ethyl methacrylate, methacrylate

  butyl acetate, lauryl methacrylate, methacrylate

  octadecyl crylate, acrylic acid, methacrylic acid,

  crylic, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, maleic anhydride, etc. Such ethylenically unsaturated monomers are

  well-known specialists and they undergo a homo-

  polymerization and copolymerization in the presence of

  the peroxygen initiator of the present invention.

  The following example shows an embodiment of the present invention but does not constitute

  in no way a limitation of any part of it.

Example

  In an autoclave made of stainless steel,

  a 2-liter container equipped with

  After stirring and a temperature control device, the following suspension formulation: 630 g of deionized water ml of a 1% aqueous solution of Methocel F-50 ml of a 1% aqueous solution Tween 60 ml of a 1% aqueous solution of Span 60 Tween 60 is polyoxyethylene monostearate aorbit.e (Atlas Chemical Industries Inc.),

  Span 60 is sorbitan monostearate (Atlas Che-

  mical Industries Inc.) and Methocel F-50 is methylcellulose having a viscosity of 50 centipoise at 200C as a 2% aqueous solution (Dow Chemical Co.). Nitrogen is bubbled through

  the aqueous solution for 15 minutes.

  0.3 g of t-amyl peroxypivalate are then charged into the reactor, and 300 g of liquefied-distilled vinyl chloride are then introduced under pressure into this reactor. The conduit of this reactor is maintained at

   C with stirring over a period of 9 hours. The pro-

  the resultant polymer is harvested with a yield

88c%.

  It will be obvious that the invention is not limited to the details given above since variants are possible without departing from the

this patent.

Claims (5)

  Process for the preparation of polymers and copolymers of ethylenically unsaturated monomers, characterized in that it consists of a bulk or suspension polymerization in the presence of a catalyst system containing t-amyl peroxypivalate as initiator.   2. Process according to claim 1,   characterized in that the monomer is the chloride of vinyl.   3. Process according to one or other of the   1 and 2, characterized in that the polymerisation   tion is carried out at a temperature of the order of   -50 C to + 70 C, in particular of the order of 20 to 60 C.   4. Process according to any one of   Claims 1 to 3, characterized in that the   t-amyl peroxypivalate at a concentration of about   0.01 to about 5.0% by weight of the polymer, in particular   in a concentration of about 0.05 to about 1.0% by weight.   Catalytic systems for the preparation of polymers and copolymers of ethylenically unsaturated monomers in a bulk or suspension system, characterized in that they contain, as an initiator, t-amyl peroxypivalate.