Process for preparation of high water-absorbent polymer beads

• US 4,446,261 A
• Filed: 03/22/1982
• Issued: 05/01/1984
• Est. Priority Date: 03/25/1981
• Status: Expired due to Term

• Current Assignee: Kao Soap Co., Ltd. (KAO Corporation)
• Original Assignee: Kao Soap Co., Ltd. (KAO Corporation)
• Inventors: Harada, Shoichiro, Yamasaki, Harumasa
• Primary Examiner(s): Kight, III, John
• Assistant Examiner(s): Nutter, Nathan M.
• Application Number:
  US06/360,496
• Time in Patent Office: 771 Days
• Field of Search: 524/27, 524/35, 524/37, 524/38, 524/39, 524/40, 524/42, 524/457, 524/501, 524/502, 524/513, 524/733, 523/201, 523/202, 523/207, 523/210
• US Class Current: 524/40
• CPC Class Codes: C08F 2/08 with the aid of dispersing agents for the polymer
• CPC Class Codes: C08F 2/14 Organic medium
• CPC Class Codes: Y10S 526/909 Polymerization characterized by particle size of product
• CPC Class Codes: Y10S 526/93 Water swellable or hydrophilic

Abstract

Water-insoluble, high water-absorbent polymer beads are prepared by dispersing and suspending an aqueous solution of a water-soluble, ethylenically unsaturated monomer containing a small amount of a crosslinking agent in a dispersion medium of a hydrocarbon or a halogenated aromatic hydrocarbon, carrying out the bead polymerization in the presence of a water-soluble radical polymerization initiator and a protecting colloid comprising a cellulose ester or cellulose ether which is oil-soluble at the polymerization temperature, and separating the resulting beads.

Claims

1. A process for preparing beads consisting of water-insoluble, crosslinked polymer, which beads have a particle size of from 100 to 1000 microns and have an absorbent capacity for physiological saline in the range of from 30 to 150 grams per one gram of the dried polymer, which consists of the steps of:

dispersing droplets of (1) an aqueous solution consisting of water-soluble, ethylenically unsaturated monomer, from 0.01 to 5% by weight, based on the weight of said monomer, of water-soluble crosslinking agent, a water-soluble radical polymerization initiator, and the balance is water, said aqueous solution containing from 30 wt.% up to the saturation concentration of said monomer, into (2) a liquid dispersion medium having a temperature of higher than 40°

C., said liquid dispersion medium consisting of an oil material selected from the group consisting of hydrocarbons having from 6 to 10 carbon atoms and halogenated aromatic hydrocarbons, and said oil material having dissolved therein from 0.05 to 10% by weight, based on the weight of said oil material, of a protective colloid selected from the group consisting of cellulose esters and cellulose ethers which are not soluble in said oil material at room temperature but are soluble in said oil material at a temperature of higher than 40°

C., whereby to form a W/O suspension of said droplets in said liquid dispersion medium, the volumetric ratio of said dispersion medium/said aqueous solution being in the range of 1;

1 to 5;

1;

suspension polymerizing said monomer, at a temperature higher than 40°

C. in the presence of said crosslinking agent and said radical polymerization initiator, whereby to form said beads; and

then recovering said beads from said liquid dispersion medium.

2. Water-insoluble, highly water-absorbent polymer beads which consist of a water-insoluble, crosslinked polymer, which beads have a particle size of at least 100 microns and have an absorbent capacity for physiological saline in the range of from 30 to 150 grams per one gram of the dried polymer, which beads are prepared by a process consisting essentially of the steps of:

dispersing droplets of (1) an aqueous solution consisting essentially of water-soluble, ethylenically unsaturated monomer, water-soluble crosslinking agent, a water-soluble radical polymerization initiator and the balance is essentially water, into (2) a liquid dispersion medium having a temperature of higher than 40°

C., said liquid dispersion medium consisting essentially of an oil material selected from the group consisting of hydrocarbons and halogenated aromatic hydrocarbons, said oil material having dissolved therein a protective colloid selected from the group consisting of cellulose esters and cellulose ethers which are not soluble in said oil material at room temperature but are soluble in said oil material at a temperature of higher than 40°

C., whereby to form a W/O suspension of said droplets in said liquid dispersion medium;

suspension polymerizing said monomer, at a temperature higher than 40°

C. in the presence of said crosslinking agent and said radical polymerization initiator, whereby to form said beads; and

then recovering said beads from said liquid dispersion medium.