High resistance gypsum parts and preparation method to obtain these parts
AssigneeInovamat, Inovacao Em Materiais Ltda
InventorsMilton Ferreira de Souza, Hebert Luis Rossetto, Wellington Massayuki Kanno
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Abstract
The preparation of gypsum parts (dihydrate calcium sulfate) with high mechanical strength is obtained with the aid of water layers with nanometric thickness. Calcium sulfate is used, dihydrate as well as hemihydrate, to obtain parts from these two materials, pure or mixed, especially to use in construction work, where the parts are prepared by compressing their slightly humidified powders.
Claims5
A gypsum part having increased mechanical strength, comprising crystals of DH and/or HH calcium sulfate wherein the gypsum part is characterized by adhesion of hydrophilic surfaces of the DH or the HH crystals to each other via hydrogen bonding with a thin layer of interstitial water between the surfaces, the layer of water thereby providing a structural connection between the crystals with reduced dynamics among water molecules;
- where a preparation method of the gypsum part uses HH calcium sulfate powder from mineral origin or from chemical processes as the starting material and is characterized by the following steps:
- (i) humidification of HH calcium sulfate powder,
- (ii) compaction of humidified powder;
- (iii) drying at temperatures around 20 degrees C. to 70 degrees C.;
- characterized by the drying being performed between 60 degrees C. and 50 degrees C.;
- characterized by the drying time between 2 and 12 h;
- and
- where the method is characterized by the additional step of surface treatment of the part by means of paints, resins and/or sealing substances.
A gypsum part having increased mechanical strength, comprising crystals of DH and/or HH calcium sulfate wherein the gypsum part is characterized by adhesion of hydrophilic surfaces of the DH or the HH crystals to each other via hydrogen bonding with a thin layer of interstitial water between the surfaces, the layer of water thereby providing a structural connection between the crystals with reduced dynamics among water molecules;
- characterized by deriving hemihydrates from mineral plaster or chemical plaster;
- and
- characterized by the adherence among the crystals occurring by means of hydrophilic polymers.
A gypsum part having increased mechanical strength, comprising crystals of DH and/or HH calcium sulfate wherein the gypsum part is characterized by adhesion of hydrophilic surfaces of the DH or the HH crystals to each other via hydrogen bonding with a thin layer of interstitial water between the surfaces, the layer of water thereby providing a structural connection between the crystals with reduced dynamics among water molecules;
- and
- characterized by preparing the part by direct compaction between 30 degrees C. and 100 degrees C. from:
- (i) slightly moistened DH calcium sulfate, where the Water/DH ratio is between 0.07 and 0.15;
- (ii) moistened DH by a suspension of urea-formaldehyde resin;
- or
- (iii) DH calcium sulfate whose crystals have their surface covered by a thin coating of a hydrophilic polymer.
A gypsum part having increased mechanical strength, comprising crystals of DH and/or HH calcium sulfate wherein the gypsum part is characterized by adhesion of hydrophilic surfaces of the DH or the HH crystals to each other via hydrogen bonding with a thin layer of interstitial water between the surfaces, the layer of water thereby providing a structural connection between the crystals with reduced dynamics among water molecules;
- and
- characterized by the preparation method of the part involving direct compaction between 30 degrees C. and 100 degrees C.:
- (i) using slightly moistened HH with Water/HH ratio between 0.05 and 0.10;
- or
- (ii) using HH crystals covered by a thin layer of urea-formaldehyde resin or polyvinyl alcohol or insoluble polyvinyl acetate after drying.
Dependencies are inferred from the claim text.