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US 7,396,924 B2Granted
Building additives based on purified hydroxyalkyl guar
AssigneeLamberti SPA
InventorsCristina Rinaldi, Ugo Pfeiffer, Giuseppe Molteni, Giuseppe Li Bassi
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Abstract
The present invention relates to highly hydroxyalkylated, glyoxal crosslinked, purified hydroxyalkyl guar useful as additive in the building industry, and to a method for its preparation.
Claims18
A dry purified hydroxyalkyl guar product, useful as an additive for building products and characterized by the facts:
- that it contains from 0.3 to 1.5% by weight of glyoxal;
- that it is not soluble at pH<7 and quickly and completely soluble at pH>8;
- that its molar substitution is between 0.4 and 2.0;
- and that it exhibits a Brookfield viscosity at alkaline pH, 20° C., 20 rpm and 2% by weight of higher than 20,000 mPa.
1 more element
A process for the preparation of a dry purified hydroxyalkyl guar product useful as an additive for building products comprising:
- a) treating, at ambient temperature, a hydroxyalkyl guar in the solid form and having a molar substitution of between 0.4 and 2.0, with an amount of glyoxal of from 2 to 3% by weight and in the form of an aaueous solution at a pH<6;
- b) washing the product of step a) with water at pH<6, for from 30 to 90 minutes, and then drying and milling it;
- wherein the dry purified hydroxyalkyl guar product is not soluble at pH<7 and quickly and completely soluble at pH>8.
Dependencies are inferred from the claim text.