Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
2003-06-27
2004-09-07
Eashoo, Mark (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C264S248000, C264S263000, C264S280000, C264S296000, C264S257000
Reexamination Certificate
active
06787086
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to multi-layer glass-reinforced sheets made from olefin polymer materials.
BACKGROUND OF THE INVENTION
Glass fiber mats have been used to reinforce various polyolefin materials. For example, U.S. Pat. No. 3,437,550 discloses the preparation of a laminate comprising a plurality of alternating plies of glass fabric and crystalline polypropylene film The glass fibers are coated with the reaction product of a silane and a crystalline polypropylene modified with an unsaturated acid or anhydride. U.S. Pat. No. 3,489,639 discloses a laminated structure comprising a sheet of polypropylene, a fabric including glass fibers and polypropylene fibers, and a layer of glass fibers embedded in a solid resin such as a polyester or epoxy resin. U.S. Pat. No. 4,435,466 discloses a multi-layered sealing sheet for the building industry comprising a glass textile reinforcing insert embedded between layers of elastomeric synthetic resin containing additives to enhance weatherability, and fillers to enhance the mechanical properties of the sheet, the outer layers being weldable thermally and/or by use of solvents or swelling agents.
U.S. Pat. No. 4,438,166 discloses a structural laminate useful for thermal insulation applications comprising a facing sheet adhered to a rigid foam layer in which is embedded a mat of long glass fibers arranged in layers, each layer being arranged parallel to the facing sheet, and a second facing sheet on the other side of the foam layer. The facing sheets are made from a flame resistant material such as asbestos, glass fibers, or metals. The foam-forming material can be, for example, polyurethane, polypropylene, or polyethylene.
U.S. Pat. No. 5,895,709 discloses a thermoformable multi-layer sheet product manufactured by pressure laminating one or more molten polymeric films such as polypropylene or polyester films, and superposed layers of glass cloth material such that the molten polymer impregnates the glass cloth layer. The core structure can be laminated on both sides with a neat polymer layer, i.e., one that is free of any reinforcing or non-reinforcing filler.
However, there is still a need for polymer sheet materials with a high flexural modulus as well as an aesthetically pleasing outer surface such as a high gloss layer or an embossed or textured layer.
SUMMARY OF THE INVENTION
The multi-layer sheet of the present invention comprises:
(1) at least one outer layer comprising a propylene polymer material selected from the group consisting of:
(a) a propylene homopolymer or a copolymer of propylene and ethylene or a 4-8 C alpha-olefin, wherein the polymerized ethylene or polymerized alpha-olefin content of the copolymer is not greater than 20%, and, optionally, about 0.15% to about 0.70% of a nucleating agent,
(b) a graft copolymer comprising a backbone of a propylene polymer material, having graft polymerized thereto polymerized monomers selected from the group consisting of (i) at least one acrylic monomer, (ii) at least one styrenic monomer, and (iii) mixtures of (i) and (ii), and, optionally, about 0.5% to about 1.5% of a nucleating agent, and
(c) 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 (1) propylene and ethylene, (2) propylene, ethylene and a C
4
-C
8
&agr;-olefin, and (3) 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 (1) ethylene and propylene, (2) ethylene, propylene, and a C
4
-C
8
&agr;-olefin, and (3) 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 decahydro-naphthalene at 135° C. of about 1.5 to about 4.0 dl/g;
the total of (ii) and (ii), 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,
(2) at least one layer comprising alternate layers of (a) a propylene polymer material selected from the group consisting of (i) a propylene homopolymer and (ii) a copolymer of propylene and ethylene or a 4-8 C alpha-olefin, wherein the polymerized ethylene or polymerized alpha-olefin content of the copolymer is not greater than 20%, wherein the melt flow rate of the propylene polymer material in layer (2) is higher than the melt flow rate of the propylene polymer material in layer (1), and (b) glass fiber mats having a weight/unit area of about 0.5 to about 4.5 oz/ft
2
, with the propylene polymer material as the top and bottom layers,
wherein layer (1) has a thickness of about 0.001 inch to about 0.25 inch.
The process of this invention for making the multi-layer sheet of this invention comprises:
(1) extruding a sheet comprising a propylene polymer material selected from the group consisting of:
(a) a propylene homopolymer or a copolymer of propylene and ethylene or a 4-8 C alpha-olefin, wherein the polymerized ethylene or polymerized alpha-olefin content of the copolymer is not greater than 20%, and, optionally, about 0.15% to about 0.70% of a nucleating agent,
(b) a graft copolymer comprising a backbone of a propylene polymer material having graft polymerized thereto polymerized monomers selected from the group consisting of (i) at least one acrylic monomer, (ii) at least one styrenic monomer, and (iii) mixtures of (i) and (ii), and, optionally, about 0.5% to about 1.5% of a nucleating agent, and
(c) 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 (1) propylene and ethylene, (2) propylene, ethylene and a C
4
-C
8
&agr;-olefin, and (3) 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 (1) ethylene and propylene, (2) ethylene, propylene, and a C
4
-C
8
&agr;-olefin, and (3) 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 decahydro-naphthalene 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;
the sheet of propylene polymer material having a thickness of about 0.001 to about 0.25 inch,
(2) forming a sheet by laying-up alternate layers of (a) a sheet of a propylene polymer material selected from the group consisting of (i) a propylene homopolymer and (ii) a copolymer of propylene and ethylene or a 4-8 C alpha-olefin, wherein
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