Weatherable Articles Containing a Weatherable Skin and a Lower Cost Core
Publication Date: 2003-Jan-28
The IP.com Prior Art Database
Described are molded weatherable articles with an outer skin of a weatherable resin and inner core of at least one second resin. Said articles are also recyclable by reason of the compatibility of skin with the core.
Weatherable products with molded-in color are useful in a wide variety of applications. Examples include automotive exterior panels, parts, and trim. In addition, in the agriculture and industrial markets examples may include tractor or industrial equipment hoods and fenders. The elimination of the painting process, not only reduces the system cost, but reduces volatile emissions associated with the painting process.
Often the weatherable resin is more expensive that the non-weatherable resin that is painted (on cost per lbs basis). Thus, while the overall systems cost of a small part manufactured by a classical injection molding process maybe cost effective over the corresponding painted part, larger parts may be less cost effective based on the amount resin needed. To further improve the systems cost and the part performance, manufactures have used processes called “IMD” or in-mold decoration. Using this method, the expensive weatherable/chemical resistant resin is placed in a mold as a thermoformed film and a less expensive resin with potentially improved structural properties is back molded behind the weatherable film.
In many cases, either because of the availability of thermoforming equipment or because of part geometry the IMD approach is not acceptable. In this case, molders have used a co-injection process where two or more resins are injected into the same mold. The first resin injected forms the external skin. The second resin injected forms the core. US Patents 6,475,413B1; 5,891,381 and references therein describe examples of these processes.
Using this method, the weatherable resin is injected first to form the skin. A less expensive resin is injected second to form the core. Optionally gas may also be injected into the core to form voids for weight reduction. These processes allow for the formation of complex weatherable parts with reduced raw material costs.
Summary Of the Invention
The present invention provides molded weatherable articles with an outer skin of a weatherable resin and inner core of second resin. Said articles are also recyclable by reason of the compatibility of skin with the core.
In one of its aspects, the invention includes articles with a skin and a core comprising:
at least one core resin and a skin layer thereon, said skin layer comprising a thermoplastic polyester different from said core material and comprising structural units derived from a 1,3‑dihydroxybenzene organodicarboxylate.
Also included are articles in which the skin layer comprises a block copolyestercarbonate. Also included are blends of polycarbonates, polyester carbonates, polyesters and polycarbonate copolymers with a copolymer comprising of structural units derived from a 1,3‑dihydroxybenzene organodicarboxylate.
In various embodiments articles are made by co-injection molding. Article compositions are resistant to loss of glos...