Wet use chopped strand glass as reinforcement in extruded products

Abstract

A method for incorporating wet use chopped strand glass (WUCS) in a screw extrusion process is provided. A polymeric resin is added to an extruder in a polymer feed zone and conveyed to a first compression zone where the resin is at least partially melted. The molten resin is conveyed to a high volume zone where WUCS fibers are added. In the high volume zone, the flights of the screw may have a greater pitch to facilitate the introduction of the WUCS into the extruder. The molten resin / fiber mixture is conveyed to a second compression zone where the resin and fibers are intimately compounded. Next, the molten resin / fiber mass is conveyed to a low pressure zone where moisture evaporated from the fibers is released through an opening. The resin / fiber mixture is then conveyed through a compression / die feed zone to further compound and mix the resin and fibers.

Description

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION [0001] The present invention relates generally to the formation of thermoplastic composites, and more particularly, to the incorporation of wet use chopped strand glass (WUCS) in an extrusion process. BACKGROUND OF THE INVENTION [0002] Typically, glass fibers are formed by drawing molten glass into filaments through a bushing or orifice plate. Normally, a sizing composition is then applied to the drawn filaments, the sizing containing lubricants, coupling agents, and film-forming binder resins. The aqueous sizing composition provides protection to the fibers from interfilament abrasion and promotes compatibility between the glass fibers and any matrix in which the glass fibers are to be used for reinforcement purposes. After the sizing composition is applied, the fibers may be gathered into one or more strands and wound into a package or, alternatively, the fibers may be chopped (typically while wet) and collected. The co...

AI Technical Summary

Benefits of technology

The present invention relates to a process for making reinforced extruded thermoplastic products using wet use chopped strand glass fibers. The process involves melting a polymer resin and adding the glass fibers in a screw extruder. The glass fibers are mixed with the resin and formed into a molten resin / fiber mix. The mix is then compressed and formed into a desired shape. The use of the wet chopped strand glass fibers in the extrusion process improves the handleability, wind resistance, and ability to withstand high temperatures and sun exposure of the resulting products.

Problems solved by technology

Unfortunately, glass reinforced vinyl siding products made from polymeric resins such as PVC would be too expensive to manufacture, primarily because dry use chopped strand glass (DUCS) requires that the glass be formed, chopped, dried, and cured prior to use in such an extrusion process; each step incurring manufacturing cost.

Such fillers may increase the modulus or stiffness of the siding product and may decrease the amount of movement that can occur as a result of a change of temperature of the siding.

However, conventional PVC siding products are limited in the loading of these fillers due to impact resistance (as required by ASTM D3679) and processing conditions, and, as a result, typically contain only a relatively small amount of inorganic fillers.

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