Method of making a sheet of building material

摘要

A method of making a sheet of building material, useful for roofing or siding applications, and the sheet material made by such method. A mixture of a thermoplastic resin and mineral filler is prepared, the resin comprising about 10% to 40% by weight of the mixture and the filler comprising about 60% to 90% by weight. The mixture is mixed at a temperature above the melting point of the resin and is formed into a sheet at such temperature. The sheet is allowed to cool until the surface is at a temperature below the midpoint of the melting range of the thermoplastic resin, e.g. in the range of 210 to 220 degrees F. (99 to 104 degrees C.), for polyethylene, at which point it is strained by passing it through calendering rollers. The sheet material made by this process, having a high concentration of mineral filler, is fire resistant, durable, ductile, of moderate weight and resistant to weathering. It can be produced using relatively inexpensive manufacturing equipment. The sheet material can incorporate a high proportion of recycled resin, such as recycled high density polyethylene.

主权项

1. A method of making a sheet of building material for roofing or siding applications, comprising the steps of:
(a) preparing a mixture comprising a thermoplastic resin and a mineral filler, said resin comprising about 10% to 40% by weight of said mixture and said filler comprising about 60% to 90% by weight of said mixture, said resin comprising one of polyethylene and polypropylene; (b) mixing said mixture at a temperature above the melting range of said resin; (c) forming said mixture into a sheet, said forming step being done at a temperature above the melting range of said resin; (d) allowing a surface of said sheet to cool to a temperature below the midpoint of the melting range of said resin, said temperature being in the range of 210 to 220 degrees F. when said resin comprises polyethylene and in the range of 220 to 250 degrees F. when said resin comprises polypropylene; and (e) straining said sheet by calendering, rolling or pressing said sheet when said surface temperature is within said temperature range of step (d) to increase a length of said sheet by 1% to 10%.