Process for polymerizing acrylic acid with inhibitor and retarder present and the use of resultant polyacrylic acids
First Claim
1. A process for the production of a polyacrylic acid in the form of small beads consisting predominantly of beads having an average diameter between 0.05 and 5 millimeters by the polymerization of monomeric acrylic acid in a vigorously stirred liquid hydrophobic reaction medium that is maintained at its boiling point in the presence of (a) a free-radical hydrophobic polymerization catalyst in an amount equivalent to between 0.05 and 5% by weight of the acrylic acid, (b) a polymerization inhibitor in an amount equivalent to between 0.02 and 0.2% by weight of the acrylic acid, and (c) a polymerization retarder in an amount equivalent to between 0.2 and 1.0% by weight of the acrylic acid, the said polymerization being effected by slowly adding to the vigorously stirred liquid hydrophobic reaction medium that is maintained at its boiling point, a solution in the liquid hydrophobic reaction medium of the monomeric acrylic acid, the said solution of monomeric acrylic acid including the free-radical catalyst (a), the polymerization inhibitor (b), and the polymerization retarder (c), or by slowly adding, to the vigorously stirred liquid hydrophobic reaction mixture containing the polymerization inhibitor (b), a solution in the liquid hydrophobic reaction medium of a stabilizer-free monomeric acrylic acid containing the free-radical polymerization catalyst (a) and the polymerization retarder (c), and subsequently recovering the resulting small beads of polyacrylic acid from the reaction medium.
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Abstract
Process of manufacturing bead-shaped polymers from acrylic acid by the polymerization of monomeric acrylic acid under slow addition of the monomer to a powerfully stirred, boiling hydrophobic reaction medium and in the presence of a free radical catalyst as well as polymerization regulator and/or cross-linking agents which comprises carrying out the polymerization in the presence of a polymerization inhibitor and/or polymerization retarder.
15 Citations
10 Claims
- 1. A process for the production of a polyacrylic acid in the form of small beads consisting predominantly of beads having an average diameter between 0.05 and 5 millimeters by the polymerization of monomeric acrylic acid in a vigorously stirred liquid hydrophobic reaction medium that is maintained at its boiling point in the presence of (a) a free-radical hydrophobic polymerization catalyst in an amount equivalent to between 0.05 and 5% by weight of the acrylic acid, (b) a polymerization inhibitor in an amount equivalent to between 0.02 and 0.2% by weight of the acrylic acid, and (c) a polymerization retarder in an amount equivalent to between 0.2 and 1.0% by weight of the acrylic acid, the said polymerization being effected by slowly adding to the vigorously stirred liquid hydrophobic reaction medium that is maintained at its boiling point, a solution in the liquid hydrophobic reaction medium of the monomeric acrylic acid, the said solution of monomeric acrylic acid including the free-radical catalyst (a), the polymerization inhibitor (b), and the polymerization retarder (c), or by slowly adding, to the vigorously stirred liquid hydrophobic reaction mixture containing the polymerization inhibitor (b), a solution in the liquid hydrophobic reaction medium of a stabilizer-free monomeric acrylic acid containing the free-radical polymerization catalyst (a) and the polymerization retarder (c), and subsequently recovering the resulting small beads of polyacrylic acid from the reaction medium.
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