31-12-2015 дата публикации
Номер: US20150376063A1
Принадлежит:
A gypsum wallboard and a method of making the wallboard using a modified beta-gypsum hemihydrate obtained by calcining gypsum in the presence of a calcination modifier, under conditions for forming a beta-gypsum hemihydrate, wherein the wallboard is prepared using a stucco slurry formed by mixing the modified beta-gypsum hemihydrate with water, pre-gelatinized starch and a stucco dispersant. 1. An ultra-lightweight gypsum wallboard comprising a set gypsum core formed between two substantially parallel cover sheets , the set gypsum core formed by hydrating a modified beta-gypsum hemihydrate in a stucco slurry comprising the modified beta-gypsum hemihydrate , water , a pre-gelatinized starch and a stucco dispersant , wherein the modified beta-gypsum hemihydrate is prepared by calcining gypsum in the presence of a calcination modifier under conditions for producing beta-gypsum hemihydrate.2. The gypsum wallboard of wherein the calcination modifier is selected from the group consisting of saturated and unsaturated claim 1 , monocarboxylic acids claim 1 , dicarboxylic acids claim 1 , tricarboxylic acids claim 1 , polycarboxylic acids claim 1 , and combinations thereof.3. The gypsum wallboard of wherein the calcination modifier is selected from the group consisting of acetic acid claim 2 , acetic anhydride claim 2 , an acetic acid salt claim 2 , adipic acid claim 2 , adipic acid anhydride claim 2 , an adipic acid salt claim 2 , aspartic acid claim 2 , aspartic anhydride claim 2 , an aspartic acid salt claim 2 , citric acid claim 2 , citric acid anhydride claim 2 , a citric acid salt claim 2 , formic acid claim 2 , formic acid anhydride claim 2 , a formic acid salt claim 2 , fumaric acid claim 2 , a fumaric acid salt claim 2 , gluconic acid claim 2 , gluconic acid anhydride claim 2 , a gluconic acid salt claim 2 , maleic acid claim 2 , maleic anhydride claim 2 , a maleic acid salt claim 2 , malic acid claim 2 , malic anhydride claim 2 , a malic acid salt claim 2 , malonic ...
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