Foamed polymer-fiber composite
AssigneeCertainTeed Corporation
InventorsDavid J. Stucky, Randall Elinski
Life of this patent
Estimating the term…
Abstract
Foamed polymer-fiber composites, building materials and methods of making such building materials are provided by this invention. The composites include about 35-75 wt. % of a polymeric resin, about 25-65 wt. % fiber and have a specific gravity of less than about 1.25 g/cc. The low density is provided by the introduction of a blowing agent or gas into a molten precursor of the composite during thermo forming, such as in an extrusion operation.
Claims20
A foamed polymer fiber composite building material, comprising:
- about 35-75 wt. % polymeric resin;
- about 25-65 wt. % fiber, and a specific gravity of less than about 1.25 g/cc, said composite building material including at least 1% porosity by volume of solids resulting from the addition of a gaseous medium or blowing agent to a molten precursor of said composite building material.
A foamed polymer—wood composite, formed from a molten mixture comprising:
- about 35-75 wt. % polymeric PVC resin, about 25-65 wt. % wood fiber, and a blowing agent or gaseous medium, said molten mixture forming a polymer—wood composite having a specific gravity of less than about 1.25 g/cc, and a flexural modulus of about 100,000-450,000 psi.
A method of forming a foamed polymer-cellulosic composite building material, comprising:
- (a) compounding about 35-75 wt. % polymeric resin, about 25-65 wt. % cellulosic fiber, and about 0.1 to 2 wt. % of a blowing agent to form a compounded mixture;
- (b) feeding said compounded mixture into an extruder, whereby said blowing agent becomes decomposed, disbursing a gas into said compounded mixture as it melts;
- and
- (c) extruding said molten mixture containing said gas through a die whereby said gas forms tiny bubbles which are trapped within said polymer-cellulosic fiber composite.
A foamed polymer wood composite building material having a generally board-shaped cross-section, formed from a molten precursor comprising:
- about 45-60 wt. % of a polyvinyl-chloride resin, about 35-55 wt. % wood flour, about 0.1-15 wt. % acrylic modifier;
- and about 0.1-2.0 wt. % of a chemical blowing agent;
- said building material having a specific gravity of less than about 1.25 g/cc and permitting a screw to be fastened flush to a surface of said building material without predrilling;
- said building material also comprising a flexural modulus of about 100,000-450,000 psi.
Dependencies are inferred from the claim text.