Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2000-05-05
2002-07-02
Mayekar, Kishor (Department: 1741)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C525S323000, C525S240000, C525S331700, C525S331900, C205S165000, C205S927000, C205S928000, C428S935000
Reexamination Certificate
active
06413652
ABSTRACT:
FIELD OF INVENTION
The present invention relates to polyolefin alloys that are specially formulated to be readily plated with various metals. These compositions can be easily processed into molded articles by molding methods, such as injection, and then plated with metal to provide a decorative or functional finish. More particularly, these compositions are blends of polyolefin homopolymers or copolymers, acrylonitrile-butadiene-styrene polymers, and styrenic block copolymers, which blends have excellent platability as well as superior physical properties including enhanced rigidity, toughness, and dimensional stability.
BACKGROUND ART
A substantial market exists for metal plated thermoplastics, particularly for applications in the automotive industry. The current overwhelming choice of plastic materials for such applications include acrylonitrile-butadiene-styrene (“ABS”) engineered resins, either alone or in polymer alloys with polycarbonates. These materials are useful due to the degree of unsaturation and polarity of the plastic which render it suitable for metal plating.
There are disadvantages in the use of ABS resins. The platable grades are relatively expensive, while the final properties of the metal plated plastic are not all that are desired. In an effort to improve upon the properties of the plastic, impact modified polypropylene blends have been utilized as alternatives. These blends include thermoplastic polyolefins and are widely used in interior and exterior automotive applications, such as bumpers, body panels, fascia, and the like. Many of these are decorated by full or partial painting for enhanced visual or functional effects.
Polypropylene is difficult to plate with metal, however, due to its lack of polarity or unsaturation. While it can be plated using special electroplating conditions, it generally is not because of cost and availability considerations. As polypropylene has certain performance advantages compared to ABS, the modification of this material to improve platability has been studied.
U.S. Pat. No. 3,655,433 discloses polyolefin alloys that are suitable for electroplating, wherein the adhesion of metal to the compositions is enhanced by incorporating into the composition a metal resinate. Crystalline polyolefins are modified with metal resins to improve the adhesion of metal thereto.
U.S. Pat. No. 3,663,260 discloses a metallizable polyolefin superimposed on a metal layer, wherein the polyolefin contains a finely divided talc having a platey (minacious) or massive (granular) particle shape. The talc filled polyolefin composition may be metallized by electroplating or other metallizing processes to form metallized shaped articles.
U.S. Pat. No. 3,918,927 discloses electroplating of polypropylene polymers containing a non-porous natural silica filler by conditioning a preformed article of the propylene polymer with a high acid content chromate conditioning agent followed by preplating the conditioning agent with an electrolessly platable metal, and then electroplating the preplated article with a final finish to obtain a metal-plated propylene polymer product.
U.S. Pat. No. 3,929,702 discloses a polypropylene composition that can be formed into a predetermined shape and can be plated with a coating of one or more metals. The polypropylene compositions comprise polypropylene polymer having a polyhydric aromatic compound and a resinous material.
U.S. Pat. No. 4,038,042 discloses polyolefin based compositions that are blends of particular proportions and types of polypropylene, low polarity rubber, highly conductive carbon black, polyethylene and optional mineral additives that provide electroplating to give adherent, plated surfaces.
Despite these patents, there still exists a need for olefinic materials containing polypropylene that are readily electroplatable utilizing conventional processes to obtain parts or components that are visually appealing as well as functional. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The invention relates to platable polyolefin blends comprising a propylene-containing polymer formed from a semi-crytalline homopolymer of propylene or a copolymer of propylene with ethylene or an alpha olefin, a polymeric compatibilizer that contains styrene and is present in an amount sufficient to facilitate adhesion between the components of the blend, and an ABS resin component of an acrylonitrile-butadiene-styrene resin or a blend of styrene-acrylonitrile resin with a diene. The ABS resin component is present in an amount sufficient to render the polyolefin blend suitable for electroplating.
In a preferred embodiment, the platable polyolefin blend includes a toughening agent of a substantially amorphous copolymer or terpolymer of ethylene and an alpha olefin. In particular, the substantially amorphous copolymer or terpolymer includes but is not limited to ethylene, an alpha olefin, and a diene or mixtures thereof.
Advantageously, the compatibilizer is a block copolymer comprising at least two different block components of styrene-ethylene/butylene-styrene, styrene-butadiene-styrene, styrene-ethylene/propylene-styrene, styrene-ethylene/butylene, styrene/ethylene-propylene, styrene-butadiene-styrene, styrene/butadiene, styrene-ethylene/propylene-styrene-ethylene/propylene, styrene/isoprene, styrene-isoprene-styrene or mixtures thereof.
Additionally, the compatibilizer can comprise copolymers of ethylene and styrene. The compatiblizer can also comprise random copolymers, random copolymers that have block segments or mixtures thereof.
In these blends, the propylene-containing polymer is typically present in an amount of about 20 to 80 weight percent, the polymeric compatibilizer is present in an amount of about 0.01 to 20 weight percent, and the ABS resin component is present in an amount of about 5 to 80 weight percent of the alloy. When present, the substantially amorphous copolymer or terpolymer of ethylene and an alpha olefin is used in an amount of about 0.01 to 30 weight percent. When an inorganic filler is included, it is typically present in an amount of about 0.01 to 30 percent by weight.
In a preferred embodiment the platable polyolefin blend is a molded article of manufacture comprising a propylene-containing polymer formed from a semi-crytalline homopolymer of propylene or a copolymer of propylene with ethylene or an alpha olefm, a polymeric compatibilizer that contains styrene and is present in an amount sufficient to facilitate adhesion between the components of the blend, and an ABS resin component of an acrylonitrile-butadiene-styrene resin or a blend of styrene-acrylonitrile resin with a diene, the ABS resin component being present to render the polyolefin blend suitable for electroplating. In a preferred embodiment the platable polyolefin blend can comprise a substantially amorphous copolymer or terpolymer of ethylene and an alpha olefin. In a particular embodiment, the substantially amorphous copolymer or terpolymer includes ethylene and an alpha olefin or a diene. In another particular embodiment the molded article of manufacture is in the form of an automotive component.
Another embodiment of the invention encompasses a process for preparing a plated polyolefin article which comprises blending a propylene-containing polymer formed from a semi-crytalline homopolymer of propylene or a copolymer of propylene with ethylene or an alpha olefin, a polymeric compatibilizer that contains styrene and is present in an amount sufficient to facilitate adhesion between the components of the blend, and an ABS resin component of an acrylonitrile-butadiene-styrene resin or a blend of styrene-acrylonitrile resin with a diene, the ABS resin component being present to render the polyolefin blend suitable for electroplating, wherein the article has a desired form, shape, and an exterior surface, and then first depositing an initial conductive metal onto at least a portion of the surface of the article, and secondly plating polyolefin article with a second metal.
In a preferred embodiment, the polyolefin artic
Ding Rui-dong
Matteucci Scott
Srinivasan Satchit
Mayekar Kishor
Solvay Engineered Polymers
Tran Thao
Winston & Strawn
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