Stock material or miscellaneous articles – All metal or with adjacent metals – Surface feature
Reexamination Certificate
2000-08-17
2001-04-17
Nutter, Nathan M. (Department: 1711)
Stock material or miscellaneous articles
All metal or with adjacent metals
Surface feature
C525S240000
Reexamination Certificate
active
06218032
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a polyolefin composition comprising (A) a propylene polymer material and (B) a partially crosslinked thermoplastic olefin elastomer composition.
BACKGROUND OF THE INVENTION
With advances in polyolefin technology, the use of polypropylene materials, particularly thermoplastic olefin materials (TPOs), in automotive applications has increased dramatically, replacing nonolefin materials such as acrylonitrile/butadiene/styrene terpolymer, polyvinyl chloride, and polycarbonate. Thermoplastic olefins are uncrosslinked blends of olefin polymers and polyolefin elastomers. New reactor product TPOs are finding use in areas such as interior trim (e.g., dashboards and door panels) due to their soft feel, thermoformability, and resistance to ultraviolet light and heat.
The process of producing these parts involves the following steps: (a) extrusion or calendering of the TPO sheet, (b) embossing (on- or off-line) of the extruded or calendered sheet to produce a textured or “grained” surface, (c) laminating and/or bonding extruded or calendered sheet to a foam or fabric for softness, (d) topcoating or painting the sheet for UV, scratch and mar resistance, and (e) forming the final part or other article from the sheet by thermoforming or low pressure injection molding.
U.S. Pat. No. 5,338,801 describes a polyolefin composition comprising (A) 70 to 90% of a propylene polymer material and (B) 30 to 10% of an olefin polymer material selected from the group consisting of (1) a partially crosslinked thermoplastic olefin elastomer composition consisting of a thermoplastic elastomer and an olefin rubber composition, (2) an uncrosslinked ethylene-propylene-conjugated diene terpolymer rubber, and (3) mixtures of (B)(1) and (B)(2). The composition provides low gloss after processing with retention of physical and mechanical properties.
A major drawback of TPOs has been their inability to retain embossed grain after the sheet is thermoformed into a large part such as a dashboard. The low melt strength and shear thinning that are typical of TPOs result in loss of the textured surface and walls that are too thin when the TPOs are formed into a part or other article.
SUMMARY OF THE INVENTION
In one embodiment, the polyolefin composition of this invention comprises, by weight,
(A) about 70% to about 40% of a propylene polymer material consisting essentially of:
(1) about 10% to about 50% of a propylene homopolymer having an isotactic index of about 80% to about 99%, or a copolymer selected from the group consisting of (a) propylene and ethylene, (b) propylene, ethylene and a CH
2
═CHR alpha-olefin, where R is a C
2-8
straight or branched alkyl group, and (c) propylene and an alpha-olefin as defined above in (1)(b), the copolymer containing about 85% to about 99% propylene and having an isotactic index of about 80% to about 98%,
(2) about 3% to about 20% of a semi-crystalline, essentially linear copolymer fraction having a crystallinity of about 20% to about 60% by differential scanning calorimetry (DSC), wherein the copolymer is selected from the group consisting of (a) ethylene and propylene containing over 50% ethylene; (b) ethylene, propylene, and an alpha-olefin as defined above in (1)(b), containing from 1 to 10% of the alpha-olefin and over 50% up to 98% of both ethylene and alpha-olefin; and (c) ethylene and an alpha-olefin as defined in (1)(b) containing over 50% up to 98% of the alpha-olefin, which copolymer is insoluble in xylene at room or ambient temperature, and
(3) about 40% to about 80% of a copolymer fraction selected from the group consisting of a copolymer of (a) ethylene and propylene, wherein the copolymer contains from 20% to less than 40% ethylene; (b) ethylene, propylene, and an alpha-olefin as defined in (1)(b), wherein the alpha-olefin is present in an amount of about 1% to 10%, and the amount of ethylene and alpha-olefin present is from 20% to less than 40%; and (c) ethylene and an alpha-olefin as defined in (1)(b), containing from 20 to less than 40% of the alpha-olefin, and optionally containing 0.5 to 10% of a diene, the copolymer fraction (3) being soluble in xylene at ambient temperature, and having an intrinsic viscosity of from 1.7 to 3.0 dl/g, wherein the total amount of fractions (2) and (3), based on the total olefin polymer composition is about 65% to about 80%, the weight ratio of fractions (2)/(3) is from 0.1 to about 0.3, and the total content of ethylene or C
4-8
alpha-olefin or combination thereof in fractions (2)+(3) is less than 50%, and
(B) about 30% to about 60% of a partially crosslinked thermoplastic olefin elastomer composition consisting essentially of:
(1) about 50 to about 125 parts by weight of a thermoplastic elastomer consisting essentially of:
(a) about 20% to about 70% of a propylene homopolymer having an isotactic index greater than 90, or a crystalline propylene copolymer with ethylene and/or a C
4-8
alpha-olefin having a propylene content greater than 85% and an isotactic index of greater than 85%;
(b) about 30% to about 75% of an amorphous ethylene-propylene or ethylene-butene copolymer fraction, optionally containing from about 1% to about 10% of a diene, which is xylene soluble at room temperature and contains from about 30% to about 70% ethylene;
(c) about 3% to about 30% of a semi-crystalline ethylene-propylene or ethylene-butene copolymer that is xylene insoluble at room temperature and contains greater than 75% ethylene; and, optionally,
(d) about 2 to about 20 parts by weight of polybutene-1 based on 100 parts of (a)+(b)+(c), wherein the ratio of polybutene-1 to the amorphous fraction (b) is less than 0.5; and
(2) about 5 parts to about 150 parts by weight of an olefin rubber material selected from the group consisting of:
(a) an ethylene/propylene copolymer rubber having an ethylene content of about 30% to about 70%, and
(b) a mixture of (i) a homopolymer of propylene having an isotactic index greater than 90, and (ii) an ethylene-propylene copolymer rubber containing about 30% to about 70% ethylene.
In another embodiment, the olefin polymer composition of this invention comprises:
(A) about 80% to about 40% of a propylene polymer material consisting essentially of:
(1) about 10% to about 50% of a propylene homopolymer having an isotactic index of about 80% to about 99%, or a copolymer selected from the group consisting of (a) propylene and ethylene, (b) propylene, ethylene and a CH
2
═CHR alpha-olefin, where R is a C
2-8
straight or branched alkyl group, and (c) propylene and an alpha-olefin as defined above in (1)(b), the copolymer containing about 85% to about 99% propylene and having an isotactic index of about 80% to about 98%,
(2) about 3% to about 20% of a semi-crystalline, essentially linear copolymer fraction having a crystallinity of about 20% to about 60% by differential scanning calorimetry (DSC), wherein the copolymer is selected from the group consisting of (a) ethylene and propylene containing over 50% ethylene; (b) ethylene, propylene, and an alpha-olefin as defined above in (1)(b), containing from 1 to 10% of the alpha-olefin and over 50% up to 98% of both ethylene and alpha-olefin; and (c) ethylene and an alpha-olefin as defined in (1)(b) containing over 50% up to 98% of the alpha-olefin, which copolymer is insoluble in xylene at room or ambient temperature, and
(3) about 40% to about 80% of a copolymer fraction selected from the group consisting of a copolymer of (a) ethylene and propylene, wherein the copolymer contains from 20% to less than 40% ethylene; (b) ethylene, propylene, and an alpha-olefin as defined in (1)(b), wherein the alpha-olefin is present in an amount of about 1% to about 10%, and the amount of ethylene and alpha-olefin present is from 20% to less than 40%; and (c) ethylene and an alpha-olefin as defined in (1)(b), containing from 20 to less than 40% of the alpha-olefin, and optionally containing 0.5 to 10% of a diene, the copolymer fraction (3) being soluble in xylene at ambient temperature, and having an intrinsic viscosity
Montell North America Inc.
Nutter Nathan M.
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