Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
2001-07-13
2004-07-06
Colaianni, Michael (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C264S328170, C264S331110, C428S311110, C428S326000, C162S218000, C162S293000, C162SDIG009
Reexamination Certificate
active
06758996
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composite formulation useful as a feedstock in the manufacture of composite end products, such as structural and non-structural construction materials, roofing tiles, fences, door panels, sound barriers, decking materials, decorative wall coverings and the like, and methods of formulating the composite.
BACKGROUND OF THE INVENTION
Composite materials based on thermoplastic polymers and wood fiber-typically in the form of milled wood products or sawdust-mixed (compounded) with each other and with additives (lubricants, adhesives, compatibilizers, etc.), and manufactured using a high volume process such as extrusion or injection molding, have been known for many years. These materials, extruded or molded into suitable profiles, can replace wood in some applications, and offer the advantages of high resistance to moisture, insects and rot, good appearance, and the absence of knots and splinters.
The prior art includes thermosetting molding compounds containing cellulose fiber as filler. For example, U.S. Pat. No. 3,367,917 describes a thermosetting melamine-formaldehyde-benzoguanamine resinous molding composition containing a fibrous filler, such as alpha-cellulose pulp, in an amount between about 25% and 42% by weight. U.S. Pat. Nos. 3,407,154 and 3,407,155 describe thermosetting urea-formaldehyde and aminoplast resinous molding composition comprising fusible reactive urea-formaldehyde and aminotriazine-formaldehyde resin, respectively, and purified alpha-cellulose fibers (14%-25% by weight) as a filler. More recent innovations in this area are described in U.S. Pat. Nos. 4,282,119 and 4,362,827. In accordance with these patents, particle boards were produced employing a binding agent which was a combination of a polyisocyanate with a aminoplast resin containing 0.25 to 0.65 mole of formaldehyde per mole equivalent of amino groups. U.S. Pat. No. 3,546,158 describes a flooring composition involving a terpolymer, a non-fibrous filler (calcium carbonate, silica, clay, kaolin, carbon black, and the like) and a fibrous filler, such as wood flour, cellulose fibers, asbestos, and the like. Compositions may include 25% to 53% by weight of non-fibrous filler and 17% to 40% by weight of fibrous filler, with the fillers accounting for 50% to 80% of the total composite weight. U.S. Pat. No. 3,720,641 describes a process of blending an aromatic polyamide molding resin with reinforcing fillers, such as glass fibers, asbestos, cellulose fibers, cotton fabric paper and the like with the fillers ranging from 2% to 70% by weight based on the total molding composition. U.S. Pat. No. 5,288,775 describes moldable thermoset acrylic polymer composites containing 3% to 15% of cellulose fibers, fillers and water; the composite is a hard, high molecular cross-linking type that requires a chemical hardener. U.S. Pat. No. 5,767,177 describes a thermosetting composition comprising 33% to 43% of a thermosetting polyester resin, 5% to 15% of cellulose fiber of wood or cotton origin, 15% to 21% of mineral fillers (calcium carbonate or hydrated alumina) and 12.5% to 22.5% of reinforcement fibers such as glass, carbon, or Kevlar. U.S. Pat. No. 5,767,178 describes a thermoset (or a cold-set) composition of a phenol-aldehyde, a urea-aldehyde or a polyurethane, mixed with cellulose fibers and latex, containing magnesium oxychloride or magnesium oxysulphate to improve fire resistance of the resulting composite. A thermosetting composition, comprising both polyvinylchlorides and polyester resins along with sawdust and mineral fillers, is also described in U.S. Pat. No. 5,783,125.
Cellulose fiber has also been used as a reinforcing ingredient in thermoplastic compositions. U.S. Pat. No. 3,856,724 describes a composite based on polypropylene or low-density polyethylene (density 0.92) and 5% to 45%, preferably 20%, by weight of alpha-cellulose (100-mesh flock) along with some additives. U.S. Pat. No. 3,875,088 describes a composite material comprising 50% to 75% of a thermoplastic resin binder (ABS or rubber-modified polystyrene) and 20%-40% of wood flour (40-mesh and 100-mesh), with the ratio of plastic to wood flour being between 1.5 and 3.0. U.S. Pat. No. 3,878,143 describes a composite material comprising 63% by weight of polyvinyl chloride or polystyrene or ABS, and 30% of wood flour along with some minor additives. U.S. Pat. No. 3,943,079 describes a composite material comprising thermoplastic polyvinyl chloride polymer and cellulose fiber as major components, the cellulose fiber being wood pulp or cotton linters in amounts ranging from 16% to 30% by weight of the total. U.S. Pat. No. 4,165,302 describes filled thermoplastic resin compositions comprising low-density polyethylene, polypropylene and other resins (in amounts ranging from 95% to 50% by weight), organic fillers (such as wood flour) and inorganic fillers (such as fly ash or calcium carbonate). The '302 patent is concerned primarily with increasing the melt flow index of filled thermoplastic resin compositions rather than their mechanical properties.
It became recognized that fillers, particularly cellulose fibers, do not disperse easily throughout the plastic formulations during mixing and molding. Accordingly, the finished products typically do not exhibit the desirable physical characteristics ordinarily associated with fiber-reinforced plastic composites. This problem has been dealt with in a number of patents. For example, U.S. Pat. No. 4,250,064 describes usage, along with low-density organic fibers (such as polyester fiber or cellulosic fiber), of a combination of coarse and fine inorganic filler such as calcium carbonate (20% to 50% by weight), which makes the organic filler more easily and uniformly dispersed in a plastic matrix (preferably chlorinated polyethylene or a vinyl chloride/vinyl acetate copolymer), avoiding visible clumps of fiber. U.S. Pat. No. 4,339,363 describes a thermoplastic resin composition involving crushed wastepaper (40% to 60% by weight), polyethylene, polypropylene or other thermoplastic resin and their combinations, and optionally an inorganic filler, such as calcium carbonate, talc, barium sulfate or the like (8% to 12% by weight). The '363 patent indicates that such compositions provide higher heat resistance, flame retardancy and mechanical strength compared with those made of synthetic resins, pure or blended with woodmeal or having incorporated inorganic filler. U.S. Pat. No. 4,343,727 describes a thermoplastic compounded injection molding material comprising polyvinyl chloride and cellulosic fiber (Solca-Floc, 5% to 20% by weight) along with epoxidized soybean oil, hydrocarbon extenders, and stearic acid as a lubricant.
Another method of improving the dispersibility of cellulose fibers in a thermoplastic matrix is described in U.S. Pat. No. 4,414,267, according to which cellulose fibers (hardwood kraft, from 1% to 40% by weight of the final composite) are pretreated by slurrying them in water, contacting them with an aqueous suspension of a mixture of a vinyl chloride polymer and a plasticizer, and drying the thus-treated fibers. Yet another approach to improving cellulose filler dispersibility is described in U.S. Pat. No. 4,559,376, according to which cellulose or lignocellulose material is subjected to a hydrolytic pretreatment using diluted hydrochloric or sulfuric acid. Essentially, the treatment converts cellulose or lignocellulose material to a fine powder of microcrystalline cellulose, which exhibits better dispersibility in a polymer matrix such as high-density polyethylene (HDPE).
Attention in the fiber-plastic composite area has been increasingly paid to improving the physical properties, such as mechanical strength, stiffness, resistance to thermal deformation, etc., of the composite products. U.S. Pat. Nos. 4,687,793 and 4,783,493 describe elimination of moisture from cellulosic fiber (wood flour, rice hulls, waste paper, pulp, etc.) before blending them with a thermoplastic polymer (polypropylene, polyethylene, ABS, polyvinyl chlori
Anderson Steven J.
Klyosov Anatole A.
Leeman David
Monovoukas Yiannis A.
Philippidis George P.
Colaianni Michael
Fontaine Monica
Kadant Composites Inc.
Testa Hurwitz & Thibeault LLP
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