Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2001-09-18
2003-01-21
Nutter, Nathan M. (Department: 1711)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C525S191000, C525S240000, C525S241000, C525S232000, C428S935000, C205S165000, C205S927000, C205S928000
Reexamination Certificate
active
06509107
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 a polymeric compatibilizer including at least one styrene monoolefin copolymer and at least one styrene diolefin copolymer, 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.
U.S. Pat. No. 4,199,491 discloses polyolefin resin compositions including block copolymers of polypropylene and polyethylene. In particular, improved plating by the high-chrome etching-catalyst method can be accomplished by blending a compound containing a cyano group with a mixture of polyolefin resin and inorganic filler. Unsaturated carboxylic acids or rubbers are also blended therein.
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-crystalline 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.
The invention also relates to platable polyolefin blends including a propylene-containing polymer formed from a semi-crystalline homopolymer of propylene or a copolymer of propylene with ethylene or an alpha olefin, a polymeric compatibilizer that includes at least one styrene monoolefin (e.g., a hydrogenated styrenic copolymer) and at least one styrene diolefin (e.g., a non-hydrogenated styrenic copolymer), wherein the styrenic copolymers are each present in an amount sufficient to facilitate adhesion between the components of the polyolefin 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. Preferably, the two or more styrenic compounds are present in a combined amount which is sufficient to facilitate adhesion between the components of the platable polyolefin blend.
In one embodiment, the at least one styrene monoolefin copolymer includes at least one hydrogenated styrenic copolymer and the at least one styrene diolefin copolymer includes at least one non-hydrogenated styrenic copolymer. Advantageously, the styrene monoolefin copolymer includes one or more random or block copolymers of styrene and a hydrogenated olefinic component; random copolymers of ethylene and styrene; or combinations thereof. The styrene monoolefin copolymers preferably include styrene-ethylene/butylene-styrene (SEBS), styrene-ethylene/butylene, styrene-ethylene/propylene-styrene, styrene/ethylene-propylene, styrene-ethylene/propylene-styrene-ethylene-propylene, or combinations thereof, and is present in an amount of about 3 to 40 weight percent of the polyolefin blend. Also, the styrene diolefin copolymer advantageously includes block or random copolymers of styrene and an unsaturated olefinic component. Preferably, this copolymer comprises styrene-butadiene (SB), styrene-butadiene-styrene, styrene-butylene-butadiene-styrene (SBBS), styrene-isoprene, styrene-isoprene-styrene, or combinations thereof, and is present in an amount of about 5 to 40 weight percent of the polyolefin blend. In a more preferred embodiment, the polymeric compatibilizer includes about 5 to 25 weight percent of a styrene monoolefin copolymer and about 7 to 25 weight percent of a styrene diolefin copolymer.
The platable polyolefin blend optionally but preferably 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 can be a block or random copolymer including at least two different block copolymers of styrene-ethylene/butylene-styrene, styrene-butadiene-styrene, styrene-ethylene/propylene-styrene, styrene-ethylene/butylene, styrene/ethylene-pr
Ding Rui-dong
Matteucci Scott
Srinivasan Satchit
Nutter Nathan M.
Solvay Engineered Polymers
Tran Thao
Winston & Strawn
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