With the rapid development of science and technology, the progress of various composite materials research techniques, especially co-extrusion compounding technology has developed rapidly since the rise of the century. Wood plastic composite co-extrusion technology has two kinds: pre-coextrusion and post-coextrusion. The former coextrusion refers to the way in which the two materials are composite and synchronously formed in the course of not being fully formed; and coextrusion refers to one. After the material has been fully formed, it is then compounded with another material. Compared with traditional pre-coextrusion technology, post-coextrusion technology has the floowing features: simple process, flexible application, low reject rate, easy recovery, and contollable adhesive strength. ASA/PE coextruded WPC are widely used in gardens, transportation, construction, home improvement, interiors and other areas. ASA/PE coextruded WPC products have gradually developed into a new industry as new material that can replace wood.
The latest research shows that due to the complex interaction between the components, the weather resistance, color loss and aging resistance of the materials will be affected, at same time, because of the use of the environment, the influence of strong UV, cold and heat changes, wind and rain erosion can also cause problems such as discoloration, chalking, cracking and srtength degradation of WPC material that are based on the raw material of low weathering plastics(PE, PP and PVC).It is understood that most of the outdoor WPC materials on the market in China at this stage of the time when there is a feeling of color fading(△E>3) is generally 15-90 days, which always trouble the industry development because of customers' complaints and related claim for compensation. Therefore, the key to development of industry is how to improve the weather resistance of WPC material. The ASA/PE co-extruded WPC can improve its related performance.
The ASA coating and PE dry mix are merged in seperate flow channel before exiting the mouth mold. The ASA melt( in a very thin thickness)is composite with the PE melt. They are extruded out of the mold; set by the mold and the water tank; and then after polished and traction, a layer of protective film is posted; and finally sawed into the specified length. The products is easy to be molded so it can be processed by ordinary plastic processing equipment or slight modification. And because the surface of WPC substrate coated by ASA is completely isolated from the environment, figuratively speaking, the ASA is a layer of armor of WPC material, it greatly improve the performance of weathering and aging resistance of WPC.
ASA structure and performance
Acrylonitrile-Styrene-Acrylic rubber terpolymer ( abbreviated as ASA) is a copolymerized by styrene-acrylonitrile resin and acrylic rubber, and it has excellent weather-ability due to its structural characteristics. In the natural environment, with superior durability, even though ASA is exposed to strong UV, moisture, heat and cold climate, it also can maintain its stability of color and physical properties. Therefore, it is the first choice for outdoor materials and has been widely used in building materials, automobiles and other fields since its inception.
As a new type of weathering material, ASA is widely used in the production of color coextruded profiles, interior and exterior wall gussets, WPC door and windows, handrails, fence, floors. ASA coextruded material provide powerful security for the improvement of WPC profile.