Methods for producing polyaspartic acids in the presence of methanesulfonic acid
First Claim
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1. A method for producing polyaspartic acids with a weight-average molecular weight (Mw) of 6000 to 15 000 g/mol, comprising the following steps:
- (i) polycondensation of(a) aspartic acid in the presence of(b) 1 to 15 mol % of methanesulfonic acid, based on the amount of aspartic acid used in (a)at a temperature of 170°
C. to 230°
C. for a time period of 1 minute to 50 hours;
(ii) subsequent hydrolysis of the polycondensates with addition of a base; and
(iii) optional acidification of the salt of polyaspartic acid obtained in (ii) with mineral acids or acidic ion exchangers, andwherein the polycondensation step further comprises the addition of water.
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Abstract
The present invention relates to methods for producing polyaspartic acids with a weight-average molecular weight (Mw) of from 6,000 to 15,000 g/mol. The invention also relates to polyaspartic acids which can be obtained by the method according to the invention, to a composition containing the polyaspartic acids, and to the use thereof as scale inhibitors, dispersants and as an additive in dishwashing agents, detergents or cleaning agents.
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20 Claims
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1. A method for producing polyaspartic acids with a weight-average molecular weight (Mw) of 6000 to 15 000 g/mol, comprising the following steps:
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(i) polycondensation of (a) aspartic acid in the presence of (b) 1 to 15 mol % of methanesulfonic acid, based on the amount of aspartic acid used in (a) at a temperature of 170°
C. to 230°
C. for a time period of 1 minute to 50 hours;(ii) subsequent hydrolysis of the polycondensates with addition of a base; and (iii) optional acidification of the salt of polyaspartic acid obtained in (ii) with mineral acids or acidic ion exchangers, and wherein the polycondensation step further comprises the addition of water. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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