Method for producing low-odor hydrogel-forming polymers
First Claim
1. A process for preparing a low-odor hydrogel-forming acrylic acid polymer, which comprises the steps of:
- a) preparing a polymeric hydrogel by free-radically polymerizing a monomer composition comprising at least 50% by weight of acrylic acid containing volatile saturated carboxylic acids selected from the group consisting of acetic acid, propionic acid and combinations thereof as impurities in a total amount of less than 400 ppm, by weight, based on the amount of acrylic acid, in an aqueous polymerization medium and converting said hydrogel into a particulate hydrogel or into hydrogel-forming powder; and
b) treating said particulate hydrogel or said hydrogel-forming powder with a crosslinking substance which, actually or latently, contains at least two functional groups capable of reacting with the carboxyl groups on the addition polymer.
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Abstract
This invention relates to a process for preparing a low-odor hydrogel-forming acrylic acid polymer, which comprises the steps of: a) preparing a polymeric hydrogel by free-radically polymerizing a monomer composition comprising at least 50% by weight of acrylic acid in an aqueous polymerization medium and converting said hydrogel into a particulate hydrogel or into hydrogel-forming powder; and optionally b) treating said particulate hydrogel or said hydrogel-forming powder with a crosslinking substance which, actually or latently, contain at least two functional groups capable of reacting with the carboxyl groups on the addition polymer; characterized by the acrylic acid used in step a) containing less than 400 ppm of acetic acid and propionic acid. It further relates to the hydrogel-forming addition polymers obtainable by the process and to their use.
21 Citations
11 Claims
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1. A process for preparing a low-odor hydrogel-forming acrylic acid polymer, which comprises the steps of:
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a) preparing a polymeric hydrogel by free-radically polymerizing a monomer composition comprising at least 50% by weight of acrylic acid containing volatile saturated carboxylic acids selected from the group consisting of acetic acid, propionic acid and combinations thereof as impurities in a total amount of less than 400 ppm, by weight, based on the amount of acrylic acid, in an aqueous polymerization medium and converting said hydrogel into a particulate hydrogel or into hydrogel-forming powder; and b) treating said particulate hydrogel or said hydrogel-forming powder with a crosslinking substance which, actually or latently, contains at least two functional groups capable of reacting with the carboxyl groups on the addition polymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification