Co-extruded laminate comprising at least one propylene graft...

Details Co-extruded laminate comprising at least one propylene graft... Co-extruded laminate comprising at least one propylene graft...

1997-04-21

2001-04-17

Thibodeau, Paul (Department: 1773)

Stock material or miscellaneous articles

Composite

Of addition polymer from unsaturated monomers

C428S304400, C428S308400, C428S318400

Reexamination Certificate

active

06218023

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to co-extruded laminates of polyolefin materials containing at least one layer of a propylene graft copolymer, and at least one layer of a polyolefin material.
BACKGROUND OF THE INVENTION
Currently structural parts, especially large structural parts, are typically 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 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; swimming pools; camper tops; household appliance cabinets and door liners; pick-up truck caps; structural and body components of golf carts; sinks; tractor hoods; automobile body panels; outdoor portable toilets; shower stalls; sinks; wall panels; counter tops, and equipment housings.
Laminates have also been produced from various combinations of polyolefin materials. However, they lack the required rigidity, scratch and mar resistance, and gloss after thermoforming.
SUMMARY OF THE INVENTION
The co-extruded laminate of the present invention comprises:
(1) at least one layer of a graft copolymer comprising a backbone of a propylene polymer material, having graft polymerized thereto polymerized monomers selected from the group consisting of
(a) at least one acrylic monomer,
(b) at least one styrenic monomer, and
(c) mixtures of (a) and (b), and
(2) at least one layer of a polyolefin material selected from the group consisting of:
(a) a crystalline homopolymer of propylene having an isotactic index greater than 80;
(b) a crystalline random 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;
(c) a crystalline random 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;
(d) 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 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 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 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% by weight of a diene, and containing less than 70% by weight of ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity 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;
(e) a thermoplastic olefin comprising:
(i) about 10% to about 60% of a propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer 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 propylene content greater than 85% and an isotactic index of greater than 85%;
(ii) about 20% to about 60% of an amorphous copolymer 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 diene and containing less than 70% ethylene and being soluble in xylene at ambient temperature; and
(iii) 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;
(f) a heterophasic polyolefin composition comprising:
(i) about 30% to about 98% of a polymeric material selected from the group consisting of a polypropylene homopolymer having an isotactic index greater than 90, and a crystalline copolymer having an isotactic index greater than 85 of propylene and at least one &agr;-olefin of the formula CH
2
═CHR, where R is H or a C
2
-C
6
alkyl group, the &agr;-olefin being less than 10% of the copolymer when R is H and being less than 20% when R is a C
2
-C
6
alkyl group or a combination thereof with R&agr;H, and
(ii) about 2% to about 70% of an elastomeric copolymer of propylene and an &agr;-olefin of the formula CH
2
═CHR, where R is H or a C
2
-C
8
alkyl group, the &agr;-olefin being about 45% to about 75% of the elastomeric copolymer, and about 10% to about 40% of the elastomeric copolymer being insoluble in xylene at ambient temperature, or an elastomeric copolymer of ethylene and a C
4
-C
8
&agr;-olefin having an &agr;-olefin content of about 15% to about 60%;
(g) mixtures of two or more of (2)(a) to(2)(f); and
(h) mixtures of one or more of (2)(a) to (2)(g) and about 5% to about 40% of a high melt strength propylene polymer material having strain hardening elongational viscosity, and
wherein about 5% to about 85% of the total thickness of the laminate comprises the graft copolymer layer (1).
The co-extruded laminates of this invention have a lower density, better weather resistance, better chemical resistance, greater toughness, and better scratch and mar resistance than materials currently available for making large thermoformed structural parts. They can also be recycled, have good thermal processing stability, are easy to pigment, and can be buffed or sanded to remove scratches. Any number of materials can be selected for the various layers, making it possible to design a wide variety of materials with whatever combination of properties is desired in the finished product. This combination of properties is not possible when using a single layer sheet.
Composite materials comprising at least one layer of this laminate attached to a low density polyolefin foam layer are another embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
The propylene polymer material that is used as the backbone of the graft copolymer in layer (1) of the laminate of this invention can be:
(a) a crystalline homopolymer of propylene having an isotactic index greater than 80, preferably about 85 to about 99;
(b) a crystalline random 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, preferably about 4%, and when the olefin is a C
4
-C
10
&agr;-olefin, the maximum polymerized content thereof is 20% by weight, preferably about 16%, the copolymer having an isotactic index greater than 85;
(c) a crystalline random terpolymer of propylene and

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