Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
1999-12-03
2002-12-03
Tarazano, D. Lawrence (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S516000, C264S173140, C264S173150, C264S173190
Reexamination Certificate
active
06489019
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to co-extruded sheets made from olefin polymer materials.
BACKGROUND OF THE INVENTION
Structural parts, especially large structural parts, have typically been made from an acrylonitrile/butadiene/styrene rubber (ABS). When weatherability is required, a laminate of ABS and a layer of acrylonitrile/styrene/acrylic resin (ASA) or an acrylic resin is used. These materials have only adequate weatherability, poor chemical resistance, and a high density, which is a disadvantage when used in applications such as, for example, co-extruded profiles; boat hulls and boat decks as well as boat engine covers, consoles, and hatches; indoor and outdoor whirlpool tubs or hot tubs; pick-up truck caps, and body parts for golf carts, all-terrain vehicles, lawn mowers and lawn tractors, and agricultural equipment.
European Patent Application 873,862 discloses co-extruded laminates comprising at least one layer of a graft copolymer made from a propylene polymer material onto which is graft polymerized acrylic and/or styrenic monomers, and at least one other layer comprising one or more polyolefin materials, which may include a high melt strength propylene polymer material. These laminates are characterized by better weather resistance, better chemical resistance, greater toughness, and better scratch and mar resistance than materials available at that time for making large thermoformed structural parts.
Glass fibers have been used to reinforce various polyolefin materials. For example, U.S. Pat. No. 5,030,682 discloses a glass fiber reinforced polyolefin resin composition consisting essentially of (a) 15-80% polypropylene-1, (b) 20-60% polybutene-1, (c) 5-60% glass fiber, (d) 0-5 parts by weight of polyolefin modified with an unsaturated carboxylic acid or unsaturated carboxylic acid derivative per 100 parts of the resin composition, and (e) 0.01-3 parts by weight of a crystal nucleating agent per 100 parts of the resin composition. The composition can be molded to make products having superior surface smoothness, superior heat resistance, and improved mechanical properties.
However, there is still a need for polymer materials having even greater melt strength that will produce thermoformed parts that have an even higher surface gloss after thermoforming than currently available materials. There is also a need for thermoformed parts with significantly increased flexural modulus and good impact strength.
SUMMARY OF THE INVENTION
The co-extruded sheet of the present invention comprises:
(1) at least one outer layer comprising (a) a propylene polymer material selected from the group consisting of (i) a propylene homopolymer or a copolymer of propylene and ethylene or a 4-8 C alpha-olefin, both having a melt flow rate (MFR) of 0.5 to 15 dg/min, wherein the polymerized ethylene or polymerized alpha-olefin content of the copolymer is not greater than 20%, and (ii) a graft copolymer comprising a backbone of a propylene polymer material, having graft polymerized thereto polymerized monomers selected from the group consisting of: at least one acrylic monomer, (II) at least one styrenic monomer, and (III) mixtures of (I) and (II), and (b) about 0.15% to about 0.70% of a nucleating agent having a melting point greater than 265° C. when the propylene polymer material is (i) or about 0.5% to about 1.5% of a nucleating agent having a melting point greater than 265° C. when the propylene polymer material is (ii), and
(2) another layer comprising:
(a) a material selected from the group consisting of (i) about 5% to about 50% of a propylene polymer having strain hardening elongational viscosity selected from the group consisting of (I) a propylene homopolymer and (II) a copolymer of propylene and ethylene or a 4-10 C alpha-olefin, provided that when the olefin is ethylene, the maximum polymerized ethylene content is 5%, and when the olefin is a 4-10 C alpha-olefin, the maximum polymerized content thereof is 20%, (ii) about 5% to about 40% of chopped glass fibers having a maximum length of ½ inch, and (iii) a mixture of (i) and (ii),
(b) optionally about 5% to about 40% of an inorganic filler, the total amount of chopped glass fibers plus inorganic filler, when present, being not greater than 50%,
(c) about 2% to about 50% of an olefin polymer composition comprising
(i) about 10 parts to about 60 parts by weight of a crystalline propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer from monomers selected from the group consisting of (a) propylene and ethylene, (b) propylene, ethylene and a C
4
-C
8
&agr;-olefin, and (c) propylene and a C
4
-C
8
&agr;-olefin, the copolymer having a polymerized propylene content of more than 85% by weight and an isotactic index greater than 85;
(ii) about 5 parts to about 25 parts by weight of a copolymer of ethylene and propylene or a C
4
-C
8
&agr;-olefin that is insoluble in xylene at ambient temperature; and
(iii) about 30 parts to about 70 parts by weight of an elastomeric copolymer from monomers selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene, and a C
4
-C
8
&bgr;-olefin, and (c) ethylene and a C
4
-C
8
&agr;-olefin, the copolymer optionally containing about 0.5% to about 10% by weight of a polymerized diene, and containing less than 70% by weight of polymerized ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity measured in decahydronaphthalene at 135° C. of about 1.5 to about 4.0 dl/g;
the total of (ii) and (iii), based on the total olefin polymer composition being from about 50% to about 90%, and the weight ratio of (ii)/(iii) being less than 0.4, wherein the composition is prepared by polymerization in at least two stages and has a flexural modulus of less than 150 MPa; and
(d) optionally about 5% to about 70% of at least one propylene polymer material selected from the group consisting of:
(i) a crystalline homopolymer of propylene having an isotactic index greater than 80;
(ii) a crystalline copolymer of propylene and an olefin selected from the group consisting of ethylene and C
4
-C
10
&agr;-olefins, provided that when the olefin is ethylene, the maximum polymerized ethylene content is 10% by weight, and when the olefin is a C
4
-C
10
&agr;-olefin, the maximum polymerized content thereof is 20% by weight, the copolymer having an isotactic index greater than 85;
(iii) a crystalline terpolymer of propylene and two olefins selected from the group consisting of ethylene and C
4
-C
8
&agr;-olefins, provided that the maximum polymerized C
4
-C
8
&agr;-olefin content is 20% by weight, and, when ethylene is one of the olefins, the maximum polymerized ethylene content is 5% by weight, the terpolymer having an isotactic index greater than 85;
(iv) a thermoplastic olefin comprising:
(1) about 10% to about 60% of a propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer from monomers selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene, and a C
4
-C
8
&agr;-olefin, and (c) ethylene and a C
4
-C
8
&agr;-olefin, the copolymer having a polymerized propylene content greater than 85% and an isotactic index of greater than 85%;
(2) about 20% to about 60% of an amorphous copolymer from monomers selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene and a C
4
-C
8
&agr;-olefin, and (c) ethylene and a C
4
-C
8
&agr;-olefin, the copolymer optionally containing about 0.5% to about 10% of a polymerized diene, and containing less than 70% polymerized ethylene and being soluble in xylene at ambient temperature; and
(3) about 3% to about 40% of a copolymer of ethylene and propylene or a C
4
-C
8
&agr;-olefin that is insoluble in xylene at ambient temperature,
wherein the composition has a flexural modulus of greater than 150 but less than 1200 MPa;
(v) a heterophasic polyolefin composition comprising:
(1) about 30% to about 98% of a polymeric material selected from the group consisting of a propylene homo
Rosenthal Jay S.
Shah Bakhtiar Alam
Basell Poliolefine Italia S.p.A.
Tarazano D. Lawrence
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