Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1993-04-26
1995-11-07
Zitomer, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
525243, 525261, 525353, 526336, 526340, 5263401, 5263297, 526342, 526910, 526911, C08F 218
Patent
active
054649153
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the production of polymeric materials or, more specifically, to methods used to prepare styrene plastics by suspension (mass-suspension) polymerization. The styrene plastics include polymers and copolymers of styrene or vinyltoluene, expandable (foamable) polystyrene or polyvinyltoluene, expandable copolymers of styrene or vinyltoluene and methylmethacrylate, copolymers of styrene or vinyltoluene and acrylonitrile, methylmethacrylate, or divinylbenzene, and impact resistant copolymers of styrene or vinyltoluene, acrylonitrile or methylmethacrylate, and rubber.
Said materials have found extensive applications in the manufacture of industrial and household products, including food packing, in the radio industries, in building and construction, lighting fixtures, electronics, electrical equipment, in the production of ion-exchange resins, in reproduction and printing technologies, etc.
DESCRIPTION OF THE PRIOR ART
Low water soluble phosphates rank as the most effective suspension stabilizers. These may be in the form of fine-sized tricalcium phosphate, hydroxyapatite, or trimagnesium phosphate powders, or freshly prepared (in-situ) tricalcium phosphate suspension obtained by pouring together aqueous solutions of trisodium phosphate and calcium chloride. In any case the low soluble phosphate reveals its suspension stabilizer function only in the presence of a surface active agent which serves to change the sign of the surface charge of the organic particles (monomer droplets or polymer beads). Normally, the surface active agent is introduced into the water before the organic suspension is obtained; no surface active agent will lead to the suspension becoming unstable, at a certain monomer conversion level different for different monomers, and to agglomeration.
There is known a method for preparing polystyrene by polymerizing styrene in an aqueous suspension in the presence of a stabilizing system comprising fine-sized tricalcium phosphate (ready-for-use), sodium bisulphate or potassium persulphate, and aminoalkanesulfonic acid as surface active agent in the amount of 0.02 to 5 wt. % (U.S. Pat. No. 4,129,707). The beads obtainable by said method feature a low size distribution index of between 12.6 and 45% (percentage ratio of standard deviation to mean bead size). The lower the bead size distribution index, the lower the content in the beads of too fine and too coarse fractions, both undesirable.
The method according to U.S. Pat. No. 4,129,707 is disadvantageous in that it uses ready-for-use tricalcium phosphate, considering that in this case very high purity levels are required of the styrene and polymerization water to be used: water conductivity to be not higher than 3.times.10.sup.-11 .OMEGA./cm. At the same time, the impurities contained in the styrene, e.g. benzaldehyde, are extracted by water in the dispersion process, leading to bead agglomeration. High source material purity requirements will increase the process costs taken on the whole. Besides, the use of aminoalkanesulfonic acid as a surfactant will complicate the waste water treatment process.
There is known a method for preparing expandable polystyrene by suspension polymerization of styrene in the presence of in-situ tricalcium phosphate and a surfactant in the form of at least one of the water soluble calcium slats of an aliphatic or aromatic carboxylic acid introduced in the amount of 0.5 to 20% of the weight of the suspension stabilizer into the water phase before styrene is dispersed therein (CS,A, 232171). In the course of polymerization, sodium dinaphtylmethanedisulfonate is added for process stabilization in the amount of 1% of the total suspension stabilizer weight when the styrene conversion reaches the level of about 75%. The method permits of obtaining beads with a mean diameter of 1.0 to 2.4 mm and a low size distribution index (14-25%).
This method, just as the one previously described, is disadvantageous in that it involves high costs due to the high source material purit
REFERENCES:
patent: 3882195 (1975-06-01), Daniels
patent: 3919355 (1975-11-01), Ballova
patent: 4433108 (1984-02-01), Keppler
Abramova Vera K.
Alexeeva Larisa V.
Amosov Viktor V.
Ballova Galina D.
Eremina Evgenia N.
Angarsk Oil Chemical Share Holding Company
Plastpolymer Share Holding Company
Zitomer Fred
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