Patent Description:
<CIT> is related to methods of reclaiming plastic from infectious medical waste and manufacturing medical devices from reclaimed plastic. <CIT> is related to treating several miscible and immiscible types of polymers to make a usable product, particularly to the advantageous treatment of such polymers that occur in wide range blends typically recovered from municipal and industrial waste streams. <CIT> is related to methods for obtaining toughened products from unsorted post-consumer plastics. <CIT> is related to fiber glass-enhanced polymer composite materials prepared from recycled plastics, processes of preparing these materials, and use of the materials for making articles having wide industrial applications.

There is a need to develop uses for recycled medical waste and other recycled plastic materials, including methods for their processing and recycling.

The present invention is defined by the granted claims. Blends of recycled plastic materials and plastic products made therefrom are described. The blends combine a high fraction of recycled medical waste with mixed recycled plastics, such as polyolefins or carpet waste. The invention provides methods for processing a heterogeneous waste stream to yield a homogenous material capable of blending with other materials and extrusion to form useful plastic products such as structural materials and consumer articles.

A blend of recycled plastics containing at least about <NUM>% by weight of recycled medical waste, or another heterogeneous recycled material, and at least about <NUM>% by weight of one or more other recycled plastics is described. The blend can further contain one or more additives, such as blending agents, colorants, binders, or fillers. The blend contains for example about <NUM> wt% recycled medical waste and about <NUM>% of one or more other recycled plastics. Alternatively, it contains about <NUM> wt% recycled medical waste and about <NUM>% other recycled plastic. In another alternative the other recycled plastic includes recycled carpet. The blend contains for example one or more of polyethylene, polypropylene, and polyester. , The blend is for example formed into a plastic product, such as a lumber product, landscape product, deck product, fence product, or railroad tie.

An aspect of the invention is a method of making a recycled plastic material. The method includes the steps of: (a) providing a recycled medical waste material, a blending agent and one or more recycled plastic materials; (b) sterilizing the recycled medical waste material; (c) shredding and blending the product of step (b); (d) adding a blending agent and the one or more recycled plastic materials to the product of step (c) ; (e) blending the product of step (d); and
and (f) optionally pelletizing or grinding the product of step (e) and optionally further comprising:(f) forming a melt from the product of step (e) or step (f); and (h) extruding the melt to form a plastic product selected from the group consisting of a lumber, landscaping timbers, railroad ties, decking material, plastic-containing furniture, playground structures, building framing materials, structural members, roofing, and flooring, wherein the surface of the product is paintable.

The invention can further be summarized through the following list of embodiments.

Plastic materials made using recycled medical waste and methods of processing medical waste or other heterogeneous waste streams to form homogenous composite plastic materials in raw form or as finished products are described.

Medical waste for use in the invention is typically in the form of bagged or boxed plastic, paper, and metal articles that have contacted patient materials or samples, or that have been implanted in a patient, and are therefore suspected of potential contamination with pathogens or toxic materials used in medical procedures, such as pharmaceutical or diagnostic agents. The waste is very heterogeneous and may contain needles, tubing, plastic syringes, and the like. Medical waste can also include materials used in the production of biotechnology products, such as cell culture materials, filters, and chromatography columns. The heterogeneity of recycled medical waste makes it nearly impossible to use to create useful homogeneous materials or new articles without significant processing and blending with other materials. In addition to recycling medical waste, the methods of the present invention also can be employed with heterogeneous waste streams, such as waste materials containing a combination of plastic, fibrous materials such as paper, cardboard, or wood, and small metal objects. Preferably the heterogeneous waste contains at least about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% by weight of plastic material, and only small amounts, such as less than about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% by weight of fibrous material, and preferably containing only small amounts of metal or other hard materials, such as less than about <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% by weight. Optionally, the waste can be hand selected or certain types of materials selectively removed by attendants who load the material into the process.

<FIG> shows a diagram of an embodiment of a recycling method of the present invention. Received medical waste is first sterilized prior to further handling. Metal objects are advantageously removed early in the process, so as to avoid interference with machinery or their accidental inclusion in final product. For example, ferromagnetic materials can be removed by exposing them to a magnet, which separates them from the non-ferromagnetic material. Then, the medical waste is shredded into small pieces so as to enhance further processing. One or more grinding processes also can be performed prior to or after shredding. After the material has been reduced to small pieces, it is blended, preferably after heating to melt the low melt plastics in the mixture. After blending, the material can be cooled and granulated to produce a raw material that can be stored and sold for other uses, or can be directly admixed with other materials, such as recycled nonmedical plastic waste, and/or with new (i.e., non-recycled) polymer materials. Blending can be enhanced by the addition of a polymer blending agent. The combined waste materials, and optionally non-waste materials, are then compounded and can be formed into a pelleted or powdered raw material. The raw material can then be further processed, such as by melting and extrusion or molding to form a plastic product. Once a melt is formed containing the medical waste, the melt can be processed to form commercial objects, such as structural lumber or building materials, railroad ties, landscaping materials, or other objects using any standard method for creating plastic articles.

Sterilization may include application of heat, chemicals, and/or radiation. For example, the sterilization process can include the addition of CaO to recycled medical waste. The sterilization process preferably results in at least a log <NUM> kill factor. After sterilization, undesired materials may be removed by magnetic separation, visual inspection and manual removal, or by other means. For example, the process can use rollers, inspection, and electromagnets for separating ferrous and/or nonferrous metals from the recycled medical waste.

Mechanical mixing steps used to combine and reduce the size of objects found in the medical waste stream can include various mixing and processing steps, such as grinding, shredding, heating, cooling, melting, or compounding of a melt with other materials. The medical waste material can be densified so as to render it suitable for gravity feed processing. Fibrous or other filler materials can be added to improve mechanical properties. High-speed grinding can be performed. Blended medical waste can be heated at one or more temperatures to achieve a suitable viscosity. Blends can be melted and extruded at a temperature such as <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), <NUM> (<NUM>°F), or <NUM> (<NUM>°F). A compounding extruder can be used in the extrusion process. In certain embodiments, the extrusion process produces an extruded material containing a core of high melt polymers and an outer layer of lower melt polymers surrounding the core.

Compositions of matter in the form of raw materials and finished products such as lumber, landscaping timbers, railroad ties, decking material, plastic-containing furniture, playground structures are described, and construction materials such as building framing materials, structural members, roofing, and flooring. The surface of products made according to the invention are paintable. For example, the surface can have a suitable level of hydrophobicity, wettability, and surface charge as to render it adherent to oil- or water-based paint applied as a spray, or by brush, roller, or dipping. Products can also be colored by inclusion of a colorant (e.g., carbon black) or dye in the blend, rendering the product made therefrom colored throughout.

The materials prepared by a method of the present invention can contain a combination of polymers obtained from processed and sterilized medical waste, optionally combined with additional polymers sourced from other recycled materials, such as carpet waste, or new polymer materials. The medical waste comprises or consists for example essentially of polypropylene (PP) and/or polyethylene (PE, which may include high density polyethylene (HDPE)). The carpet waste comprises or consists for example essentially of polyethylene terephthalate (PET) and or PP. Additional polymers that can be added as new materials or in the form of recycled plastics include polyamide (PA), nylon, polycarbonate (PC), polyvinylchloride (PVC), polystyrene (PS), polyester, liquid crystal polymers (LCP), and mixtures thereof, as well as copolymers such as ethylene vinyl acetate (EVA) useful to promote blending.

The materials made by methods of the invention include recycled medical waste in an amount by weight of at least <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%. Materials made by methods of the invention include one or more other recycled plastic materials, or new, non-recycled plastic materials, in an amount by weight of at least <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%. Materials made by methods of the invention include one or more blending agents (e.g., EVA) in an amount by weight of <NUM>-<NUM>%, such as <NUM>%, <NUM>%, <NUM>%, or <NUM>%. The materials made by methods of the invention further can contain one or more types of filler or inclusions, such as polymer fibers, carbon fibers, graphene, metals, inorganic oxides, nanoparticles, nanotubes, and the like. Colorants such as carbon black or dyes also can be added. Preferred blends according to the invention include a blend of <NUM>-<NUM>% by weight recycled medical waste and <NUM>-<NUM>% by weight recycled polyolefin (primarily a blend of PE and PP), such as <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin, <NUM>% recycled medical waste and <NUM>% recycled polyolefin, or <NUM>% recycled medical waste and <NUM>% recycled polyolefin. Other preferred blends include a blend of <NUM>-<NUM>% recycled medical waste and <NUM>-<NUM>% recycled carpet material, such as motor vehicle trunk liner material (a blend of approximately <NUM>% PP and <NUM>% PET), such as <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material, <NUM>% recycled medical waste and <NUM>% recycled carpet material, or <NUM>% recycled medical waste and <NUM>% recycled carpet material. For the above described blends, <NUM>% refers to the weight of recycled plastic materials in the blend. In addition, small amounts (less than about <NUM>%, less than about <NUM>%, or less than about <NUM>% by weight of the final composition) of one or more colorants and one or more blending agents and one or more fillers can be added.

Materials made by methods of the invention can be provided in different forms, including pellets, powder, as well as extruded structural members or lumber in the form of boards, sheets, or any other desired shape. The materials can be produced in a variety of different particle sizes, useful as a raw material for different purposes, such as a µm (mesh) size of <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), <NUM> (<NUM>), or <NUM> (<NUM>) µm (mesh).

Four different blends of recycled plastic materials were prepared. The composition of the blends is shown in Table <NUM> below. In Table <NUM>, <NUM>% represents the total of all recycled plastic materials, without including additives such as blending agents or colorants.

The recycled medical waste was prepared by sterilizing the medical waste, removing metals, blending the medical waste with the indicated amounts of other recycled plastic materials. The mixed recycled plastic contained about <NUM> wt% polyolefin (e.g., PE and PP) with the remainder being predominately PC, PVC, and/or PET. The recycled carpet was motor vehicle trunk liner cuttings containing approximately <NUM> wt% PP and <NUM> wt% PET. The final material of each blend additionally contained approximately <NUM>% carbon black as colorant, as well as <NUM>% or less of EVA as blending agent.

<FIG> shows transmission infrared spectra of Blend A in solid form and ground form, together with standard reference materials (SRM) of PE, PP, and polyester. The blend apparently contained contributions from PE, PP, and polyester, in the relative amounts of PE > PP > polyester. The spectra and composition of ground and solid materials appeared essentially identical.

<FIG> shows transmission infrared spectra of Blend D in solid form and ground form, together with standard reference materials (SRM) of PE, PP, and polyester. TL refers to recycled trunk liner (carpet) material. The blend showed contributions from PE, PP, and polyester, with a higher amount of polyester than Blend A. The relative amounts appeared to be PE > polyester > PP. Since PET was present in the carpet material, and PET is a type of polyester, at least a portion of the polyester spectrum observed in the blend was probably due to PET.

The Blends A and D, whose IR spectra are shown in <FIG> and <FIG>, were ashed to remove all organic material, leaving only inorganic filler or residue, which was identified and quantified by energy dispersive X-ray spectroscopy (EDXS). The results are shown in Table <NUM> below for the material extruded in the form of lumber as well as extruded, reground material.

Blends A-C described in Example <NUM> were extruded to form plastic lumber products in different formats, including nominal <NUM> (<NUM>) x <NUM> (<NUM>) cm (inch) boards (actual dimensions <NUM> (<NUM>) cm (inches) x <NUM> (<NUM>) cm (inches) x <NUM> (<NUM>) cm (inches) length) and nominal <NUM> (<NUM>) x <NUM> (<NUM>) cm (inch) posts (actual dimensions <NUM> (<NUM>) cm (inches) x <NUM> (<NUM>) cm (inches) x <NUM> (<NUM>) cm (inches)). These products were subjected to mechanical testing according to standard ASTM protocols, and the results are described below.

Fastenal Premium All Purpose Deck Screws (#<NUM>, <NUM> (<NUM>) x <NUM> (<NUM>) cm (in)) were installed in plastic lumber products on a face, edge, and cut end of each lumber specimen. The specimen was then conditioned at the indicated conditions for <NUM>-<NUM> hours prior to testing. Increasing load was applied to the installed screws until either the screw or the lumber substrate failed, and the load at time of failure is reported in Table <NUM> as the average of <NUM> determinations (average of <NUM> determinations for the <NUM>°F, <NUM>% RH condition).

Fastener stability was best for Blend C in the <NUM> x <NUM> (<NUM> x <NUM>) format, while for the <NUM> x <NUM> (<NUM> x <NUM>) format fastener stability was better for Blend B than for Blend A. In both formats, lowering the temperature increased fastener stability, and raising the temperature weakened fastener stability. Soaking in water had little or no effect.

Plastic lumber specimens were conditioned for at least <NUM> hours at <NUM> (<NUM>°F), <NUM>% relative humidity (RH). Load was increased until the board failed due to flexural rupture. For the <NUM> x <NUM> (<NUM> x <NUM>) lumber the support span was <NUM> (<NUM> inches), the load span was <NUM> (<NUM> inches), and the load was applied to the nominal <NUM> (<NUM> inch) face. For the <NUM> x <NUM> (<NUM> x <NUM>) lumber the support span was <NUM> (<NUM> inches) and the load span was <NUM> (<NUM> inches). Results presented in Table <NUM> are average values from five specimens.

Flexural stability was greatest for Blend A, and least for Blend C.

Lumber specimens were subjected to compressive loading perpendicular to the length of the boards. Load was applied to the nominal <NUM> inch faces of the <NUM> x <NUM> (<NUM> x <NUM>) lumber. Load was applied until <NUM>% strain was achieved. Results presented in Table <NUM> are average values from five specimens.

Resistance to compression was similar for Blends A-C.

The bulk density and specific gravity of plastic lumber specimens were measured by water displacement at <NUM> (<NUM>°F). The lumber was preconditioned according to ASTM D618 prior to testing. One inch pieces of the lumber specimens were cut with a miter saw, and cut edges were covered with packaging tape. Results presented in Table <NUM> are average values from five specimens.

The bulk specific gravity and density were greatest for Blend B.

As used herein, "consisting essentially of" allows the inclusion of materials or steps that do not materially affect the basic and novel characteristics of the claim. Any recitation herein of the term "comprising", particularly in a description of components of a composition or in a description of elements of a device, can be exchanged with "consisting essentially of" or "consisting of".

Claim 1:
A method of making a recycled plastic material, the method comprising the steps of:
(a) providing a recycled medical waste material, a blending agent and one or more recycled plastic materials;
(b) sterilizing the recycled medical waste material;
(c) shredding and blending the product of step (b);
(d) adding a blending agent and the one or more recycled plastic materials to the product of step (c);
(e) blending the product of step (d); and
(f) optionally pelletizing or grinding the product of step (e)
and optionally further comprising:
(g) forming a melt from the product of step (e) or step (f); and
(h) extruding the melt to form a plastic product selected from the group consisting of a lumber, landscaping timbers, railroad ties, decking material, plastic-containing furniture, playground structures, building framing materials, structural members, roofing, and flooring, wherein the surface of the product is paintable.