Ectrudable cement core thermoplastic composite

[0002] This claims benefit of provisional application 60/017,397 filed May 14, 1996.

[0003] Vinyl siding has long been used as exterior cladding for residential construction. It possesses good long term appearance retention. However, it suffers from several shortcomings. Color choice is limited due to heat build-up limitations. In addition, its strength (or stiffness) and thermal expansion behavior also limit its use. Finally, vinyl siding will soften, melt, or burn when exposed to high temperatures.

[0004] Cementious materials, such as Hardiplank® and Hardipanel™, have been used for residential siding. These materials possess good strength, thermal expansion behavior, and fire resistance. However, they require post-treatment, such as painting, in order to have acceptable aesthetics and resistance to environmental abuse.

[0005] Therefore, there is a need for a siding material which has good strength, thermal expansion characteristics, and fire resistance, as well as good long term appearance retention.

[0006] FIG. 1 is a partial cross-section of the siding of the present invention.

[0007] The present invention is a panel for use in siding. The panel comprises a cement core in a shape defining the panel of the siding and a plastic film layer attached to the cement core. The plastic film layer is selected from the group consisting of polymers and copolymers of vinyl chloride. The panel may also include an adhesive layer which adheres the plastic film layer to the cement core. The cement core preferably contains fiber reinforcement. The plastic film layer preferably surrounds the cement core.

[0008] The siding panel of the present invention is shown in FIG. 1. The siding panel 10 has a cement core 15. The cement core 15 contains fiber reinforcements 20. The cement for the core may be any typical cement. The fibers used for reinforcement can be cellulose fibers, for example. A plastic film layer 25 is attached to the cement core 15 of the siding panel 10. The plastic film layer 25 is preferably made of polymers or copolymers of vinyl chloride. The plastic film layer 25 may be attached to the cement core 15 directly. Alternatively, an adhesive layer 30 may be used to attach the plastic film layer 25 to the cement core. Any adhesive which will adhere to the cement core and to the plastic film layer can be used.

[0009] The cement layer 15 and the plastic film layer 25 could be formed separately, followed by a lamination step attaching the plastic layer 25 to the cement core 15. Alternatively, the cement layer 15 could be coextruded with the plastic film layer 25, and the adhesive layer 30, if desired, through an appropriate die configuration, such as cross-head extrusion, to form the siding panel. The plastic film layer 25 may be attached to one side of the cement core 15 or to both sides. Coextrusion would allow the cement core 15 to be completely surrounded by the plastic film layer 25.