CS219596B1 - A method of suspension polymerization and copolymerization of acrylic monomers - Google Patents

Abstract

The invention relates to the preparation of acrylic polymers and copolymers by suspension polymerization. It solves the problem of suspension stability during polymerization. The necessary stability of the polymerization system consisting of phosphate and calcium carbonate is achieved by using as an additional emulsifier dodecylbenzenesulfonic acid neutralized with an amine, e.g. monoethanolamine in an amount of 0.001-0.01% by weight, calculated on the weight of the aqueous phase.

Description

219,596 (54) Spnsnb suspension polymerization and acrylic polymerization polymerization 1

BACKGROUND OF THE INVENTION The present invention relates to suspension polymerization and copolymerization of acrylic monomer solutions to improve suspension stability during polymerization.

Due to the easy removal of the polymerization heat, the suspension polymerization is in the manner of preparation of acrylic polymers and copolymers. The formation of a suspension, mixing of the monomer, respectively. monoers with dissolved additives, such as initiators, dyes, or a molecular weight regulator in water, such as the initial polymerization stage, up to about 30% conversion to the polymer will have difficulty in correctly selecting the mixer, its rotation and the polymerization temperature. however, about 30-40% of the conversion rate increases the tackiness of the polymerizing bead to their unruly agglomeration. suspension stabilizer. Two groups of substances are used in the polymerization of acrylic monomers. On the one hand, they are water-soluble macromolecular substances (which, by virtue of the structure of the molecule, are classified as protective colloids (gelatin, starch, vinyl alcohol, poly (meth) acrylic acid or salts thereof), and other inorganic substances which are insoluble in water. These substances, such as kaolin, aluminum hydroxide, magnesium hydroxide or calcium phosphate, must be present in the polymerization system in a very fine form and stabilize by enveloping the mono-droplets. by adding a small amount of emulsifier, e.g., an alkaline salt of a sulfonated aromatic hydrocarbon, as described in AO 157 242. The mechanism of coupling the emulsifier in this system is similar to that of emulsion polymerizations, ie, forming a hydrophobic surface toward the monomer phase droplet and however, the summary is currently The use of a pulverulent inorganic powder and a small amount of emulsifier causes the monomeric particles to have larger, larger dimensions than those of emulsion polymerization. From the optical quality of the products prepared from the suspension polymers and the co-polymers of the acrylic type, it is preferred that the polymer be as uniform as possible so that the amount to the polymerization charge of the added components such as suspension stabilizers is as low as possible. Therefore, the efficiency requirements of the high stabilizer are 2. To some extent, their spin-stabilized target system. calcium phosphate and alkali alkylarylsulfonate, e.g. sodium dodecylbenzenesulfonate.

It has now been found that a higher stabilizing effect on the polymerizing suspension is achieved if instead of! the sodium solialkylarylsulfonic acid is used to neutralize the acid with amines, e.g., ethanolamine. The higher effect is seen in the fact that with the same dosing of all the components of the batch and keeping the same polymerization conditions a smaller average grain of the suspension polymer is achieved and that the grain is very uniform. In order to achieve the same average grain size as the addition of the alkali salt of dodecylbenzenesulfonic acid, a lower addition of the target is sufficient. calcium phosphate, which results in an improvement in the optical quality of the polymer. We will translate and document the above-mentioned effect of the novel process in the following examples. Príkl. 1 was carried out using dodecylbenzenesulfonate, e.g. 2 and 3 by an improved process of the invention using mono-ethanolamine neutralized dodecylbenzenesulfonic acid. Example 1

1180 kg of steam condensate and 810 kg of monomeric methyl methacrylate containing a polymerization initiator and a molecular weight regulator were charged into a 2.5 m 3 polymerization vessel, and the stabilization system formed a target. dicalcium phosphate prepared under stirring at 60 ° C by precipitation from 1694 g of dibasic sodium phosphate (content 20.8% w / w) and 1512 g calcium chloride. Other stabilizing ingredients of additive 770 g of calcium carbonate and 17 g of sodium dodecyl benzenesulphonate dispensed in an aqueous solution. Polymerization blended with 110 rpm. min. 1 at 70 ° C until exothermic polymerization occurred. The post-polymerization at 95 ° C for 1.5 h was then carried out. hydrochloric acid, the polymer was centrifuged and then dried under washing, and the granulation of the obtained polymer is shown in the table after Example 2.

Claims (1)

PREDMF.T A process for the suspension polymerization and copolymerization of acrylic monomers using a phosphate and calcium carbonate stabilization system with the addition of an emulsifier, characterized in that an amine-neutralized dodecylbenzenesulfonic acid, for example monoethanolamine, in an amount of 0.001-0.01 wt. calculated on the weight of the aqueous phase.