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US 12,668,538 B2Granted
High temperature sag resistant lightweight gypsum board
AssigneeKnauf Gips KG
InventorsMark Hemphill, Qinghua Li
Life of this patent
Estimating the term…
Abstract
A high temperature sag resistant lightweight wallboard. The addition of a small amount of urea (about 0.1%) significantly improves the high-temperature sag resistance on Type X gypsum wallboards. These gypsum wallboards may have a board weight of less than 2100 lbs/msf when cast to have an overall 5.8 inch thickness, and may include glass fibers and/or mineral wool. Also, methods of making the gypsum wallboard and a wall system for employing the gypsum wallboard.
Claims19
A gypsum board comprising:
- a gypsum core layer comprising
- at least 70 wt. % calcium sulfate dihydrate,
- and
- 0.2-0.5 wt. % urea distributed uniformly throughout the gypsum core,
- 0.1 to 1.0 wt. % glass fiber or 0.5 to 10 wt. % mineral wool as reinforcing material,
- 0.5 to 3 wt. % pregelatinized, partially hydrolyzed starch,
- 0 to 0.4 wt. % phosphate,
- 0 to 1.0 wt. % dispersant,
- optionally vermiculite,
- optionally an accelerator,
- optionally a retarder,
- and an absence of clay additive,
- wherein the gypsum core layer results from setting of a mixture comprising an addition of urea provided in dry form or an aqueous solution admixed to an aqueous slurry comprising calcium sulfate hemihydrate and water,
- wherein the gypsum core has air voids,
- wherein the gypsum core layer has a density of 30-40 pounds per cubic foot, and
- wherein the gypsum board has a mass of pounds per area 1600 to 1886 lbs/msf, wherein the mass of pounds per area lbs/msf values are for a ⅝ inch thick board and subject to proportional adjustment for thicker or thinner boards,
- wherein the board has a thickness of ⅜″-1″,
- wherein the gypsum core layer has opposed front and back outer surfaces, further comprising a front cover sheet on the gypsum core front surface and a back cover sheet on the gypsum core back surface, and
- wherein the front and/or back cover sheets are made of paper or fiberglass.
16 more elements
A gypsum board having a gypsum core layer between front and back cover sheets, the gypsum core layer made from a mixture of:
- an aqueous slurry comprising water and at least 70 wt. % on a dry basis calcium sulfate hemihydrate,
- 0.03-1 wt. % on a dry basis urea in dry form or an aqueous solution,
- 0.1 to 1.0 wt. % glass fiber or 0.5 to 10 wt. % mineral wool,
- 0.5 to 3 wt. % pregelatinized, partially hydrolyzed starch,
- 0 to 0.4 wt. % phosphate,
- 0 to 1.0 wt. % dispersant,
- 0 to 1.0 wt. % dispersant,
- optionally an accelerator,
- optionally a retarder,
- optionally sodium trimetaphosphate,
- an absence of clay additive,
- optionally vermiculite,
- water, and
- air,
- wherein the mixture results from a process comprising an addition of urea admixed to the aqueous slurry comprising the calcium sulfate hemihydrate and the water,
- wherein the gypsum core layer has a density of 30-40 pounds per cubic foot or less,
- wherein the gypsum board has a mass of pounds per area 1600 to 1886 lbs/msf, wherein the mass of pounds per area lbs/msf values are for a ⅝ inch thick board and subject to proportional adjustment for thicker or thinner boards,
- wherein the gypsum board has a thickness of ⅜″-1″,
- wherein the gypsum core layer has opposed front and back outer surfaces, the front cover sheet on the gypsum core front surface and the back cover sheet on the gypsum core back surface, and
- wherein the front and/or back cover sheets are made of paper or fiberglass.
17 more elements
Dependencies are inferred from the claim text.