Polyolefin wood fiber composite

Details Polyolefin wood fiber composite Polyolefin wood fiber composite

1999-04-16

2001-07-24

Pyon, Harold (Department: 1772)

Stock material or miscellaneous articles

Light transmissive sheets, with gas space therebetween and...

C428S036700, C428S036900, C428S297400, C052S749100, C052S749100

Reexamination Certificate

active

06265037

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to composite materials for structural members used in commercial and residential architecture and specifically in the manufacture or fabrication of fenestration units such as windows and doors. The composite is made using an extrusion process with an input of polyolefin and wood fiber to form a composite material having improved properties. The materials have improved processability, thermal and structural properties when compared to metal, vinyl, or wooden components and when compared to other polymeric or polyolefin composites. The structural members of the invention can be used in the form of elements used in institutional and residential construction such as framing members, beams, sized lumber, trim, siding, shingle, jambs, stiles, sills, tracks, sash and other components. These applications can require a low cost, complex, thin-walled, hollow profile structural member. The composite can be made with intentional recycle of by-product or waste streams comprising components used in the manufacture of the fenestration unit, if desired.
BACKGROUND OF THE INVENTION
In conventional construction materials and in window and door manufacture, vinyl, vinyl composite, wood and metal components are used in forming structural members. Most commonly siding, trim, window or door units are typically made from extruded vinyl or aluminum or milled wood members. Such materials and units made of these materials, require maintenance and are often energy inefficient. Vinyl materials have been used in forming envelopes, profile and seal components in window units. Such vinyl materials typically comprise a major proportion of vinyl polymer with inorganic pigments, fillers, lubricants, etc. Extruded or injection mold of thermoplastic materials have been used, filled and unfilled as flexible and rigid thermoplastic materials used in seals, trims, fasteners, and other window construction parts. Thermoplastic polyvinylchloride has been combined with wood members in the manufacture of PERMASHIELD® brand windows manufactured by Andersen Corporation for many years. The technology is disclosed in Zaninni, U.S. Pat. Nos. 2,926,729 and 3,432,885. Generally, PVC materials is used as a cladding or coating. The PVC technology used in making PERMASHIELD® brand windows involve extruding or injection molding thin polyvinylchloride coating or envelope onto a shaped wooden structural member. One useful alternative to vinyl envelopes around wood members is a polyvinylchloride wood fiber composite such as that disclosed in patents assigned to Andersen Corporation including U.S. Pat. Nos. 5,406,768; 5,441,801; 5,486,553; 5,539,027; 5,497,594; 5,695,874; 5,518,677; 5,827,607 and published European Patent Application No. 586,212, and others.
Polyolefin materials such as polyethylene and propylene, common polyolefin compositions, have been available in a variety of grades and forms for many years. In large part, polypropylene has not been used in exterior applications or as exterior structural members due to its limited structural capacity and its inability to resist the damaging effect of weather, typically heat, light and cold. Recently, polypropylene has been used in a variety of applications in which the polypropylene is combined with a reinforcing composition in a variety of ways. For example, Shinomura, U.S. Pat. No. 3,888,810, teaches a thermoplastic composite comprising a thermoplastic resin, fibrous materials and preferably synthetic or natural rubbers. Jones, U.S. Pat. No. 3,917,901, teaches a conductor having an insulative layer comprising a polyolefin-wood composite. Nakano et al., U.S. Pat. No. 3,962,157, claim a polypropylene composition modified with a porous filler and a free radical agent that promotes reaction between the filler and the polymer. Laver, U.S. Pat. No. 5,516,472, claims an apparatus and method for making a composite which forms, internally, pellet-like strands that are then recombined to form an extruded part. Bainbridge et al., U.S. Pat. No. 5,766,395, claim a self-supporting composite structure in the form of a panel made by compression molding composite materials. The prior art also discloses a large proportion of patents that compatibilize a combination of a polyolefin with a cellulose filler using such materials as plasticizers, monomeric silicone containing compounds, grafted silyl moieties on either the polymer or the filler, polyolefin lubricants, blends of varied types of polymers in combination with the primary polyolefin, synthetic elastomers and rubbers, methylol phenolic modified polyolefins, blends of ethylene polymers and polypropylene polymers, in situ polymerization of monomers onto a fiber used in the making of a composite, specialized fibers including polytetrafluoroethylene fibers, expanded or otherwise specially modified polyolefins, glyoxal and other types of thermally reactive crosslinking agents, modified cellulosic fibers including the use of metals, crosslinking agents, compatibilizing agents, etc. Wold, U.S. Pat. No. 5,435,954, teaches a molding method for forming a composite into a useful article.
The polypropylene art has shown significant advancement and sophistication in learning to obtain new physical properties from polypropylene, various fibers and reagents or other polymers. Representative examples of recent developments in the manufacture of polypropylene compositions, particularly metallocene catalyst manufactured propylene, is shown in the technical literature owned by Montell North America Inc. For example, Malucelli et al., U.S. Pat. No. 5,574,094, teach improved polyolefin compositions comprising one or more crystalline materials having a melt index higher than 20 grams-10 min
−1
combined with a cellulosic particle or fiber. Malucelli et al. disclose pelletizing such a composite and converting such a pellet into products by way of injection molding. Sacchetti et al., U.S. Pat. No. 5,691,264, disclose a bimetallic metallocene catalyst containing at least one M-&pgr; bond combined with a support comprising magnesium halide in the gas phase polymerization of an olefin such as propylene into a structural polymeric product. In particular, these catalysts obtain the polymerization of olefins such as propylene into high molecular weight useful materials. The patent literature describes bimetallic catalysts comprising a compound of titanium or vanadium supported on a magnesium halide reactive with a metallocene compound containing at least one cyclopentadienyl ring coordinated on a transition metal selected from V, Ti, Zr, Hf, or mixtures thereof. Examples of such catalysts are described in U.S. Pat. No. 5,120,696, EP-A-447070 and EP-A-447071. The bimetallic catalysts can be obtained by impregnating a silica support with a magnesium compound of the type MgR
2
, wherein R is a hydrocarbon radical and then reacting the treated support with a compound of Ti, such as TiCl
4
, optionally with SiCl
4
and thereafter with a metallocene compound. Such materials are shown in EP-A-514594. Such bimetallic catalysts obtained by these treatments and then with other titanocenes such as dicyclopentadienyl titanium dichloride and bis(indenyl) titanium dichloride are shown in EP-A-412750. Similar catalysts obtained by treating carbonated compounds of magnesium such as alkyl magnesium carbonate, with titanium dichloride in the presence of a metallocene compound of Hf or Zr, are known from PCT Application WO 94/03508. Bimetallic catalysts comprising a titanium based catalyst in which the Ti compound is supported on a Mg halide, a metallocene compound and a poly(methylaluminoxane) (a MAO) are disclosed in EP-A-436399. Sacchetti et al., U.S. Pat. No. 5,698,487, disclose additional compositions and methods for preparation of metallocene catalysts for preparing polyolefin materials. Govoni et al., U.S. Pat. No. 5,698,642, disclose a particular gas phase polymerization project having two interconnected polymerization zones for olefin polymerization. Sacchetti et al., U.S. Pat. No. 5,759,940, disclose further information on the

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