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US 4,024,014 AGranted
Non-combustible hardboard sheet
AssigneeConwed Corporation
InventorDavid Wallace Akerson
Life of this patent
Estimating the term…
Abstract
A process for preparing a non-combustible hardboard sheet is disclosed. The process comprises the formation of relatively low density insulation board type product which is dried, whereafter the board is wetted on both sides and compressed at relatively high temperatures to form a dense non-combustible hardboard product.
Claims7
A process for producing a hardboard product having a fire rating of Class A according to ASTM Test E-84 comprising:
- a. forming an aqueous slurry of solids and water said solids consisting essentially of the following ingredients:
- i. from about 75% to about 85% by weight mineral material, said mineral material consisting essentially of:
- A. from about 20% to about 85% mineral fibers;
- B. from 0% to about 50% perlite;
- C. from 0% to about 5% of other mineral materials;
- ii. from about 15% to about 25% of a binding system, said binding system consisting essentially of:
- A. from about 5% to about 15% by weight cellulosic fibers;
- B. from about 10% to about 20% of a heat and moisture re-activatable binding agent;
- b. forming a relatively light product by depositing the said aqueous slurry on a forming screen;
- c. drying the said formed product to a moisture content of no greater than about 3% by weight;
- d. applying to each side of the dried product from about seven pounds per thousand square feet to about fifteen pounds per thousand square feet of water;
- e. simultaneously heating and pressing the formed product to reduce its thickness by a factor of at least 2.5 and to increase its density to at least 50 pounds per cubic foot.
9 more elements
A process for producing a hardboard product having a fire rating of Class A according to ASTM Test E-84 comprising:
- a. forming an aqueous slurry comprising from about 95% to about 98% water and from about 2% to about 5% solids, said solids consisting essentially of the following ingredients:
- i. from about 75% to about 85% by weight mineral material, said mineral material consisting essentially of:
- A. from about 20% to about 85% mineral fibers;
- B. from 0% to about 50% perlite;
- C. from 0% to about 5% of other mineral materials;
- ii. from about 15% to about 25% of a binding system, said binding system consisting essentially of:
- A. from about 5% to about 15% by weight cellulosic fibers;
- B. from about 10% to about 20% of a heat and moisture re-activatable binding agent;
- B. forming a relatively light product by depositing the said aqueous slurry on a forming screen;
- c. drying the said formed product to a moisture content of no greater than about 1% by weight, said dried product having a density of from about 20 to about 23 pounds per cubic foot;
- d. applying to each side of the dried product from about seven pounds per thousand square feet to about fifteen pounds per thousand square feet of water;
- e. simultaneously heating at a temperature of from about 300.degree. to about 400.degree. F. and pressing with a minimum pressure of at least about 300 p.s.i. the formed product to reduce its thickness by a factor of at least 2.5 and to increase its density to at least about 50 pounds per cubic foot, the simultaneous heating and pressing being for a period of from about 30 seconds to about five minutes.
9 more elements
Dependencies are inferred from the claim text.