JPS5863702A - Stabilizer for monomer suspension polymerization - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a highly active stabilizer for suspensions used in the polymerization and copolymerization of monomers such as styrene, α-methylstyrene, divinylbenzene, acrylonitrile, and acrylic and methacrylic esters.

The stabilizer generally used in polymerization systems is calcium phosphate or calcium polyphosphate, and it is
0.6% by weight is used. The activity of the stabilizer is greatly influenced by the manufacturing method and the addition of modifiers that have the ability to coat the surface of the polymerized beads dispersed in the aqueous solution.

Borland Patent & No. 72906 K discloses a method for precipitating calcium phosphate salts directly in a polymerization reactor by adding an aqueous solution of sodium phosphate into an aqueous solution of calcium chloride together with the dissolved sodium salt of a copolymer with tostyrene maleate. has been done. Stabilizers prepared in this way give good results when polymerization is carried out at temperatures up to 100°C, but at higher temperatures,
The stabilizing effect of this protective colloid is insufficient.

Borland Patent A99897 also discloses a method for preparing stabilizers for spunsion polymerization at high temperatures. In the pouring method, a precipitate of calcium polyphosphate is formed using a suspension of calcium hydroxide or lime water containing a small amount of a compound of magnesium and ammonium and dilute phosphoric acid. The product thus produced is mixed with demineralized water and used as a suspension in a polymerization system.

A fundamental property parameter of suspension stabilizers is their ability to uniformly coat the surface of polymerized beads of monomer suspended in an aqueous solution.

This ability depends on the stabilizer's structure, molecular size and type of surface charge.

Research into improving the properties of stabilizers has been directed toward modifying calcium phosphate with anticaking agents. As a result, it was unexpectedly found that calcium salts of acetic acid or propionic acid are good as inhibitors. When these compounds are added to calcium phosphate, they are adsorbed onto the surface of the molecule and their dissociation is limited, thereby reducing the surface charge and increasing the phosphate calcium phosphate obtained by known methods in the form of apatite hydroxide. The stabilizer of the present invention, which is 20% by weight of calcium phosphate, contains 5 to 20% by weight of calcium salt of acetic acid or calcium salt of propionic acid, based on the mass of calcium phosphate.

The stabilizer composition according to the invention is used in the polymerization process in an amount up to 35% by weight of dry solids as a suspension liquid, or in the form of a powder after drying and pulverization.

This powder can be mixed with water and swelled to create a beautiful suspension.

The stabilizer according to the present invention has considerably higher activity than known stabilizers and can reduce the concentration in the polymerization process, thereby reducing production costs and contributing to the reduction of harmful industrial waste. Moreover, this stabilizer is characterized in that the size of the produced polymer is within a predetermined range, so that scattering of the produced granules is suppressed.

The stabilizer according to the invention will be explained in more detail in the Preparation Examples. Comparative studies on the stability of styrene in suspension polymerization processes demonstrate its advantages.

Example 1: Into a mixer equipped with a high-speed stirrer, approximately 30 g of dry mass calcium phosphate and 25 g of calcium acetate aqueous solution 2'
1 ooxg of a wet precipitate of calcium phosphate containing o dcy+t was added. After stirring for 2 hours, a homogeneous suspension solution of stabilizer was obtained.

[Example 2] The amount of calcium acetate added was 2.5 d as a 25% aqueous solution.
The same operation as in Example 1 was repeated except that i* was reduced.

[Example 3] The same operation as in Example 1 was repeated except that 2 (l) of an aqueous solution of calcium propionate xodcrl was added to the mixer instead of calcium acetate.

[Example 4] An O-generated suspension prepared as a stabilizer in the same manner as in Example 1 was dried and ground into powder using an impact mill.

Stabilizers 0.15 and 0.15 made according to Examples 1-4.
An aqueous solution containing 0.05% by weight was used for the suspension polymerization of styrene and the suspension copolymerization of styrene and divinylbechizen. Polymerization was carried out correctly. The size of the obtained beads is 0.25-0.75.1! and buckwheat accounted for 97 tons of the total amount of product. The physico-chemical properties and processability of the polymer were within standard limits.

In the suspension polymerization of styrene, the effects of calcium phosphate containing 5% by weight of acetic acid are compared with those without the addition of a modifier and are shown in Table '1.

Table 1 1) 7 acids 1. Amount of stabilizer in aqueous solution Stability (
(% by weight) Used alone 0.1' 5 Good Used alone 0.05 Lump-Bad Good results were also obtained when the stabilizer of the present invention was used in the suspension polymerization of methacrylic acid ester.

Patent Applicant Ojlodek Badav Ezorozv Oyoviker Uzhkov I. Tovorziv0Vynilovitch Continuation of page 1 @l! Inventor: Roman Nilczak Jr. - Ōswięciřim Zabórzkiego, Boland 187 [Phase] Inventor: Josek Grěszló Poland: Ōświęciřim Śrzyłaczia Szłołowaciego 5/7 0 Inventor Inirzy Muranski Poland Aşwięcim Uliczá Spital 160152

Claims (2)

[Claims] (1) Stabilizers for suspension polymerization of monomers of styrene, α-methylstyrene, divinylbenzene, acrylonitrile, or acrylic acid and methacrylic esters, the stabilizer is in the form of apatite hydroxide. is calcium phosphate obtained by a known method, and the stabilizer is characterized by containing 5 to 2 (0% by weight) of a calcium salt of acetic acid or a calcium salt of propionic acid to the mass of calcium phosphate. stabilizer. (2) The stabilizer according to claim 1, which is used in the polymerization process in the form of a suspension liquid of a dry mass at 35% by weight 1, or in the form of a powder after drying and pulverization.