WO2001023471A1 - Article thermostable, composition de latex, et procede de fabrication - Google Patents

Article thermostable, composition de latex, et procede de fabrication Download PDF

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Publication number
WO2001023471A1
WO2001023471A1 PCT/US2000/026653 US0026653W WO0123471A1 WO 2001023471 A1 WO2001023471 A1 WO 2001023471A1 US 0026653 W US0026653 W US 0026653W WO 0123471 A1 WO0123471 A1 WO 0123471A1
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WO
WIPO (PCT)
Prior art keywords
article
methacrylate
acrylate
composite material
ofthe
Prior art date
Application number
PCT/US2000/026653
Other languages
English (en)
Inventor
Daniel B. Derbyshire
Charles J. Mcdonald
Harry A. Rubbright
David A. Spears
Original Assignee
The Dow Chemical Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Dow Chemical Company filed Critical The Dow Chemical Company
Priority to AU76208/00A priority Critical patent/AU7620800A/en
Publication of WO2001023471A1 publication Critical patent/WO2001023471A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
    • C04B26/02—Macromolecular compounds
    • C04B26/04—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/003—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor characterised by the choice of material
    • B29C39/006—Monomers or prepolymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D81/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package
    • B65D81/343—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package specially adapted to be heated in a conventional oven, e.g. a gas or electric resistance oven
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
    • B29K2033/04—Polymers of esters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0058—Liquid or visquous
    • B29K2105/0064—Latex, emulsion or dispersion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/16—Fillers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2233/00—Use of polymers of unsaturated acids or derivatives thereof, as reinforcement
    • B29K2233/04—Polymers of esters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2205/00—Venting means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2581/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D2581/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2581/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D2581/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within
    • B65D2581/3401—Cooking or heating method specially adapted to the contents of the package
    • B65D2581/3402—Cooking or heating method specially adapted to the contents of the package characterised by the type of product to be heated or cooked
    • B65D2581/3405—Cooking bakery products
    • B65D2581/3406—Pizza or bread
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D81/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package
    • B65D81/3446—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package specially adapted to be heated by microwaves
    • B65D81/3453—Rigid containers, e.g. trays, bottles, boxes, cups
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00948—Uses not provided for elsewhere in C04B2111/00 for the fabrication of containers

Definitions

  • the present invention relates to a heat stable article, and more particularly, to a method of forming a heat stable article such as an ovenable container which includes a latex composition and which may be heated to high temperatures in an oven without generating objectionable odors.
  • disposable containers which can be used to package and cook food
  • disposable containers may be used to package frozen foods which may then be heated within the container.
  • Such containers have been typically formed from paper, paperboard, plastics such as polystyrene and polyethylene terephthalate, metals such as aluminum, or combinations of these materials.
  • plastics such as polystyrene and polyethylene terephthalate
  • metals such as aluminum, or combinations of these materials.
  • polymeric materials fail both at low temperature applications due to embrittlement and breakage, and at high temperature applications due to degradation and the generation of an offensive odor.
  • Dual ovenable containers are typically formed from plastic or paperboard; however, such materials are limited for use in conventional ovens at temperatures of less than about 400°F. At higher temperatures, such containers tend to degrade, darken, deform, and emit odors, resulting in an unfavorable appearance and smell, both for the container and the food contained therein.
  • a number of coatings have been developed for paperboard substrates to increase their heat resistance for use as ovenable containers.
  • Seung et al., U.S. Patent No. 5,494,716 teach an aqueous coating including a styrene-acrylic latex which provides heat resistance.
  • Katsura et al., U.S. Patent No. 5,078,939 teaches a heat resistant container formed from a laminate of a paper substrate and an aqueous dispersion of a hiding pigment and a thermosetting epoxy-acrylic resin.
  • Calvert, U.S. Patent 5,418,008, teaches a barrier coating for paperboard packing comprising a water-based emulsion coating of an acrylic copolymer resin and a high density polyethylene wax.
  • coatings have been found to provide heat resistance only up to about 400°F to 450°F. For some applications, it is desirable to heat food for short periods of time at higher oven temperatures of up to 600°F. Moreover, such coatings only protect the base material of the container.
  • the base material has intrinsic limitations based on its ability to withstand heat and remain odor free. For example, paper and paperboard stock are limited by the thermal decomposition of cellulose. Inorganic materials such as calcium carbonate or clay would make ideal packaging material for high temperature cooking, but their use has been limited due to the difficulties involved in being able to form such materials into geometrically complex shapes.
  • a heat stable article such as a disposable container and method of making it which may be used to package and/or cook foods and which contains a latex composition which may be used in an oven at high temperatures without generating objectionable odors from the container, and without introducing an objectionable flavor to the food.
  • the present invention meets that need by providing a heat stable article and a method of forming the article from a filled composite material containing fillers, fibers, and a polymeric binder.
  • the article can be used as an ovenable container used to cook foods in an oven such as a conventional or microwave oven at high temperatures (i.e., oven temperatures greater than 400°F, and preferably greater than 450°F and up to 600°F) without generating an objectionable odor from the container or introducing an objectionable flavor to the food.
  • the container also may be used to store or package frozen foods.
  • heat stable it is meant an article which is capable of withstanding temperatures up to 600°F without substantial chemical or structural degradation.
  • a heat stable article comprising a filled composite material comprising a filler, a fibrous material, and a binder selected from the group consisting of natural and synthetic latexes and natural and synthetic dispersed polymers.
  • the filler provides the bulk portion ofthe article and is inert and thermally stable for ovenable cooking.
  • the filler also provides the article with a good surface for cooking.
  • the filled composite material preferably comprises from about 20 to 90% by weight ofthe filler, and more preferably, from about 60 to 80% by weight ofthe filler.
  • the filler is preferably selected from the group consisting of calcium carbonate, talc, clay, or combinations thereof.
  • the fibrous material imparts tensile strength and flexural stability to the article.
  • the fibrous material is preferably selected from the group consisting of cellulose, polyester, glass, nylon, polypropylene, polyethylene, acrylic, rayon, aramid, polystyrene, or combinations thereof.
  • the filled composite material may comprise from about 2 to 40% by weight fibers, and more preferably, from about 4 to 20% by weight total fibers.
  • the filled composite material comprises from about 4 to 15% by weight cellulose fiber, and from about 1 to 5% by weight polyester fiber.
  • the filled composite material comprises from about 4 to 15% by weight cellulose fiber and from about 1 to 5% by weight nylon fiber.
  • the filled composite material comprises from about 4 to 20% by weight cellulose fibers.
  • the filled composite material comprises from about 4 to 20% by weight nylon. In yet another embodiment, the filled composite material comprises from about 4 to 20% by weight polyester.
  • the binder functions to bind the various components ofthe final article together and to impart cohesiveness and other desired properties.
  • the filled composite material preferably comprises from about 2 to 30% by weight ofthe binder, and more preferably, from about 10 to 20% by weight.
  • the binder preferably comprises a latex formed from at least one "soft” monomer, or at least one "hard” monomer, or a combination thereof, such that the resulting polymer has a glass transition temperature of between 0 and 125°C.
  • latex it is meant any dispersed, water- insoluble natural or synthetic polymer or copolymer which is in the form of a colloidal dispersion or suspension.
  • Synthetic polymers are typically formed by radical polymerization of monomer droplets emulsified in an aqueous medium.
  • the polymerized particle is colloidally dispersed and stable or nearly stable in an aqueous medium and has an individual particle size of about 0.05 to 5 ⁇ m in diameter. See J.M.G. Cowie, Polymers: Chemistry & Physics of Modern Materials, International Textbook Company Limited, 1973.
  • soft monomer it is meant a monomer whose homopolymer glass transition temperature is less than about room temperature (25°C).
  • hard monomer it is meant a monomer whose homopolymer glass transition temperature is greater than about room temperature (25°C).
  • the soft monomer is preferably selected from the group consisting of methyl acrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, vinylidine chloride, or combinations thereof.
  • a preferred soft monomer is methyl acrylate.
  • the hard monomer is preferably selected from the group consisting of methyl methacrylate, ethyl methacrylate, acrylonitrile, vinyl chloride, or combinations thereof.
  • a preferred hard monomer is methyl methacrylate.
  • the latex also preferably includes a polymerizable emulsion stabilizer which provides appropriate colloidal or near colloidal stability to the composite material.
  • the binder preferably includes, based on total monomers, from about 0.5 to 3% by weight ofthe polymerizable emulsion stabilizer, which is preferably selected from the group consisting of fumaric acid, itaconic acid, acrylic acid, methacrylic acid, acrylamide, 2-hydroxyethyl acrylate, and sulfopropyl methacrylate.
  • a preferred polymerizable emulsion stabilizer is itaconic acid.
  • the latex also preferably comprises, based on total monomers, from about 0.1 to 3% by weight of a molecular weight modifier such as a cross linking agent or a chain transfer agent to control the molecular weight and other physical properties ofthe polymer.
  • a molecular weight modifier such as a cross linking agent or a chain transfer agent to control the molecular weight and other physical properties ofthe polymer.
  • the molecular weight modifier is preferably selected from the group consisting of glycidyl methacrylate, allyl methacrylate, trimethylol propane triacrylate, n-methylol methacrylamide, and ethyl glycol dimethacrylate.
  • a preferred molecular weight modifier is glycidyl methacrylate.
  • the latex preferably comprises, based on total monomers, from about 0.1 to 99% by weight methyl acrylate, from about 0.1 to 99% by weight methyl methacrylate, from about 0.1 to 5% by weight of a polymerizable emulsion stabilizer, and from about 0 to 3% by weight of a molecular weight modifier. More preferably, the latex comprises from about 20 to 40% by weight methyl acrylate, from about 60 to 80% by weight methyl methacrylate, from about 0.5 to 3% by weight of the polymerizable emulsion stabilizer, and from about 0 to 3% by weight ofthe molecular weight modifier.
  • the binder comprises a natural or synthetic dispersed polymer.
  • Such polymers have limited or no water solubility and can be selected from those polymers that can be mechanically dispersed or which are self-dispersing.
  • Such polymers can be synthetically manufactured polymers, naturally occurring polymers, or derivatives of naturally occurring polymers.
  • the filled composite material preferably further includes a colloidal destabilization additive or additives which function to bind the filler, fiber and binder into a larger aggregate structure during the process of forming the container.
  • a colloidal destabilization additive or additives which function to bind the filler, fiber and binder into a larger aggregate structure during the process of forming the container.
  • colloidal destabilization By “causing colloidal destabilization” ofthe mixture, it is meant that the inherent electrostatic, steric and solvation forces that repulse the separate components of the formulation are removed and/or inhibited to the extent that the materials come into close association in macro-structures.
  • the colloidal destabilization additive(s) function to form the individual particles mechanically dispersed in the aqueous medium into soft floes or macro- particles.
  • the colloidal destabilization additive is preferably selected from the group consisting of flocculants, cationic sources, or combinations thereof.
  • the filled composite material preferably comprises from about 0 to 4% by weight of the coll
  • the colloidal destabilization additive comprises a flocculant which is selected from the group consisting of cationic amine polymer-epichlorohydrin adducts, cationic starches, gums, phenolic resins, polyamines, polyacrylamides, urea-formaldehyde, melamine-formaldehyde, polyamides, quarternary amines, polyethyleneimines, colloidal silica, and bentonite clays.
  • a flocculant which is selected from the group consisting of cationic amine polymer-epichlorohydrin adducts, cationic starches, gums, phenolic resins, polyamines, polyacrylamides, urea-formaldehyde, melamine-formaldehyde, polyamides, quarternary amines, polyethyleneimines, colloidal silica, and bentonite clays.
  • the colloidal destabilization additive comprises a cationic source selected from the group consisting of cationic amine polymer-epichlorohydrin adducts, alum, and quaternary amines.
  • the filled composite material further comprises from about 0.1 to 10% by weight of a coloring agent selected from the group consisting of carbon black, titanium dioxide, iron oxides, inorganic pigments, organic pigments, dyes and lakes.
  • a coloring agent selected from the group consisting of carbon black, titanium dioxide, iron oxides, inorganic pigments, organic pigments, dyes and lakes.
  • the coloring agent comprises carbon black.
  • the heat stable article ofthe present invention is preferably formed from a dilute mixture of the filled composite material containing water in which the formation occurs primarily through the draining of a substantial portion of water from the mixture.
  • the shaped article may then optionally be trimmed, coated, laminated or surface treated for protection.
  • shaped article it is meant an article having a three-dimensional configuration with at least one dimension having a nonplanar surface.
  • Colloidal destabilization of the mixture is preferably caused by the addition of the colloidal destabilization additive(s) described above.
  • the colloidal destabilization additive(s) may be added to the composite mixture in a batch process, or alternatively in a continuous process.
  • the resulting destabilized material is preferably fed to a formation tank by gravity.
  • the mixture is formed into a shaped article by depositing an amount of the filled composite material onto a first tool which is then mated to a second tool.
  • the first tool is a vented formation tool and the second tool is a vented transfer tool.
  • the filled composite material is preferably applied to the first tool either by immersing the tool into the formation tank of the dilute destabilized mixture or by applying the filled composite material directly to the tool in a quantity sufficient to form the article.
  • the filled composite material is drawn onto the first tool by use of a vacuum and/or pressure system which pulls the water through the tool but traps the solid material on a porous surface that is contoured in the desired shape. Once sufficient material is drawn on to the screen, the tool is mated to a second heated tool. In this method, a substantial amount of water is removed from the system by vacuum drainage.
  • the mixture is formed into a shaped article by drawing an amount ofthe mixture onto a first tool, transferring the mixture to a second tool, and then pressing the article in a vented press.
  • a substantial amount of water is also removed by vacuum drainage.
  • the article can be pressed while the article is still wet or it can be pressed after the article is dried.
  • the mixture is formed into a shaped article by placing the colloidally destabilized mixture on a moving wire mesh where substantial drainage of water is used to form a sheet.
  • the sheet is then applied to a first tool which is then mated to a second tool.
  • the sheet may be dried prior to applying it to the first tool.
  • the method of the present invention may further include providing one or more barrier layers in or on the article.
  • the barrier layer functions to prevent grease or oils in the food from penetrating the container and/or to prevent the absorption of material from the container into the food.
  • the barrier layer(s) may also function to prevent oxygen transport through the article.
  • the barrier layer(s) may comprise single or multiple ply films formed by techniques known in the art including co-extrusion. Suitable barrier layer materials include nitrile resins, polycarbonates, polyethylene terephthalate, polyethylene terephthalate copolymers, polyvinylidene chloride, polyvinyl chloride, polyolefins, cellulose ethers, or combinations thereof.
  • the method of making the article as described above may also be used to make a lid adapted to seal the container. This may be beneficial, for example, to maintain freshness of food during storage and/or delivery.
  • the lid of the container may be comprised of materials such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyolefins, paper, paperboard, or molded pulp. If desired, the lid and or the container may be embossed or printed.
  • the lid may also include one or more optional barrier layers as described.
  • the lid could be sealed using a film or other material commonly used in the food industry such as Saran®, polyethylene, polyethylene terephthalate, poly(vinyl alcohol), polypropylene, polyvinyl chloride, or modified atmosphere packaging.
  • the method of the present invention may be used to form a variety of shaped articles which are suitable for use in a wide range of environmental conditions including temperatures well below freezing to oven conditions, and a humidity range from very low to saturated.
  • Useful articles made in accordance with the method ofthe present invention include ovenable containers, food storage containers, protective packaging devices, embossed floor tiles, and plastic housing replacements.
  • the container preferably comprises a container body including a base and surrounding sidewalls defining an opening for containing food.
  • a lid may also be provided which is adapted to be fitted onto the peripheral edge ofthe sidewalls.
  • the container of the present invention may be used to cook food by placing food in the container and heating the container in an oven at temperatures of up to 600EF for a period sufficient to cook the food; wherein no objectionable odors are generated from the container during heating, and without any substantial degradation, discoloration, or deformation of the container.
  • the container may be used as a pizza pan in which dough may be added, sealed with the lid, optionally frozen, and then delivered to a cooking location where the dough is thawed, ingredients added, and a pizza cooked and served or delivered with the lid in place all within the same container.
  • the container may also be used to cook foods in microwave ovens, as well as ovens which use a combination of heat, light, convection or air jets, and/or microwaves.
  • the container may also be used to cook a wide variety of other foods including frozen or refrigerated soups, frozen or refrigerated meats, frozen entrees, and frozen or refrigerated casseroles.
  • the container can be filled with food, sealed with a lid or film, stored, and then cooked and served within the same container.
  • Fig. 1 is a schematic illustration of a fine pulp molding process used to form a shaped article in accordance with the present invention
  • Fig. 2 is a schematic illustration of an alternative embodiment ofthe method shown in Fig.
  • FIG. 3 is a schematic illustration of a paper-making process used to form a shaped article in accordance with the present invention
  • Fig. 4 is a schematic illustration of an alternative embodiment ofthe method shown in Fig. 3;
  • Fig. 5 is a perspective view illustrating a container and lid formed in accordance with the present invention.
  • Fig. 6 is a cross-sectional view ofthe container and lid where the container includes a barrier layer
  • Fig. 7 is a perspective view illustrating the lid mounted on the container.
  • the article ofthe present invention comprises a filled composite material which is formed from a composite formulation of a filler, fibers, and a binder.
  • Suitable fillers for use in the composite formulation include any organic or inorganic, natural or synthetic filler which will withstand the high temperatures required for using the container.
  • suitable fillers include calcium carbonate (precipitated, ground limestone, whiting, etc.), barium carbonate, magnesium carbonate, calcium fluoride, sodium aluminum fluoride, aluminum hydroxide, aluminum, bronze, lead, zinc, aluminum oxide, aluminum trihydrate, calcium oxide (cement), magnesium oxide, silicon dioxide (silica: colloidal sol, diatomaceous, novaculite, pyrogenic, quartz flour, vitreous, wet process), titanium dioxide, zinc oxide, silicates (kaolin clay, montmorillonite clay, hectorite clay, calcined kaolin, calcium silicate, feldspar, glass tripolite, mica, muscovite, phlogopite, vermiculite, nephiline, pyrophyllite, perlite, talc, woUastonite), barium sulfate (barite, blanc fixe), calcium sulfate (gypsum, anhydrite, precipitated), lithopone, zinc sulf
  • the filled composite material comprises from about 20 to 90% by weight of the filler, and preferably, about 60 to 80% by weight, and is preferably selected from the group consisting of calcium carbonate, talc, and clay or blends of these materials.
  • the fibers may be organic or inorganic, natural or synthetic, and may include, by way of example, cellulose fibers (cotton, flax, wood pulp [soft and hard wood, refined and unrefined, bleached and unbleached], other plant pulp), protein fibers (wool, silk, alginate, casein fiber), rayon fibers, cellulose acetate fibers, cellulose triacetate fibers, acetate fibers, acrylic fibers, aramid fibers (Kevlar®, Nomex®), azlon fibers, glass fibers, modacrylic fibers, novaloid fibers, nylon fibers (type 6, etc.), nitrile fibers, olefin fibers, (polyethylene, polypropylene, etc.), polystyrene fibers, polyester fibers (polyethylene terephthalate, etc.), polyurethane fibers (Spandex, etc.), vinyl fibers, benzoate fibers, poly(hydroxyacetic acid ester) fibers, Teflon
  • Prefened fibers for use in the present invention include cellulose, nylon, polyester, glass, polypropylene, polyethylene, acrylic, rayon, aramid, or polystyrene fibers, or blends of such fibers.
  • Preferred natural fibers for use in the present invention are cellulose fibers, which may comprise up to about 40% by weight of the filled composite material.
  • the cellulose fibers (including soft and hardwood fibers or cotton fibers), preferably have a length of about 0.5-5 mm.
  • Preferred synthetic fibers are polyester fibers, which may comprise up to about 40% by weight ofthe filled composite material and more preferably between about 1 to 20% by weight ofthe filled composite material.
  • These synthetic fibers preferably have a length of about 1-10 mm, and more preferably, about 2-7 mm, with a denier of about 1 to 8, and preferably from 1.5 to 6.
  • the binder used in the composite formulation may include natural and synthetic latexes and natural and synthetic dispersed polymers.
  • the prefened binder for use in the present invention is a synthetic latex.
  • the latex used in the present invention is preferably formed from the emulsion polymerization of a soft monomer and a hard monomer.
  • soft monomer it is meant a monomer whose homopolymer glass transition temperature is less than about room temperature (25°C) as measured by any traditional technique such as dynamic scanning calorimetry.
  • hard monomer it is meant a monomer whose homopolymer glass transition temperature is greater than about room temperature (25°C) as measured by any traditional technique such as dynamic scanning calorimetry.
  • Monomers falling on or near room temperature (25°C) can be classified as either hard or soft.
  • the monomer compositions should be controlled such that 1 ) the final polymer will withstand the high temperatures required for using the article, and 2) the glass transition temperature (T g ) is maintained between about 0 to 125°C, and preferably between about 60 to 90°C.
  • T g glass transition temperature
  • This glass transition temperature can be achieved with homopolymers whose glass transition temperature normally falls within this range when measured by an appropriate method such as dynamic scanning calorimetry.
  • a methyl acrylate homopolymer has a T g of approximately 8°C.
  • comonomers must be added such that the Fox equation would reasonably predict a copolymer glass transition temperature in the correct range.
  • a form ofthe Fox equation is as follows:
  • Prefened soft monomers for use in the present invention include acrylate monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, n-propyl acrylate, iso-propyl acrylate, sec-butyl acrylate, t-butyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, benzyl acrylate, methyl phenyl acrylate, tolyl acrylate, ethoxyethyl acrylate, methoxybutyl acrylate, iso-bornyl acrylate, cyclohexyl acrylate, and cycloheptyl acrylate.
  • acrylate monomers such as methyl acrylate, ethyl acrylate,
  • Suitable soft monomers include methacrylate monomers such as n-butyl methacrylate, hexyl methacrylate, iso-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, octadecyl methacrylate, amyl methacrylate.
  • methacrylate monomers such as n-butyl methacrylate, hexyl methacrylate, iso-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, lauryl methacrylate
  • Additional soft monomers include butadiene, isoprene, chloroprene, 1 -pentenylene, fluoroprene, vinylidene chloride, vinylidene bromide, chlorotrifluoroethylene, 1 , 1 -dichloro-2-fluoroethylene, vinylidene fluoride, tetrafluoroethylene, vinyl acetate, vinyl sterate, vinyl versatate, vinyl pelargonate, benzoyloxyethylene, 4-butyryloxybenzoyloxyethylene, 4-ethylbenzoyloxyethylene, trifluoroacetoxyethylene, heptafluorobutyryloxyethylene, formyloxyethylene, 2-methoxy- benzoyloxyethylene, pivaloxyloxyethylene, propionyloxyethylene, vinyl propionate, and vinyl n- butyrate.
  • Methyl acrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, and vinylidene chloride are prefened for use in the present invention because of their lack of odor contribution during cooking at high temperatures. Methyl acrylate is the most prefened.
  • This monomer preferably comprises from about 0.1 to 99% by weight ofthe polymer, more preferably from about 5 to 55% by weight ofthe polymer and most preferably from 20 to 40% by weight of the polymer.
  • the latex preferably comprises, based on total monomers, about 3 to 40% by weight ethyl acrylate, and more preferably, from about 5 to 25% by weight.
  • the latex preferably comprises about 2 to 35% by weight n-butyl acrylate, and more preferably, from about 3 to 20% by weight.
  • the latex preferably comprises about 5 to 50% by weight n-butyl methacrylate, and more preferably, from about 15 to 35% by weight.
  • the latex preferably comprises from about 20 to 70% by weight vinylidene chloride, and more preferably, from about 35 to 55% by weight.
  • Prefened hard monomers for use in the present invention include methacrylate monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and iso-propyl methacrylate; styrene-based monomers such as styrene, vinyl toluene, ⁇ -methyl styrene, 2-methyl styrene, ethylstyrene, iso-propylstyrene, 4-butylstyrene, t-butylstyrene, 4-hexylstyrene, 4- phenylstyrene, 4-acetylstyrene, 3-(4-biphenylyl)styrene, 4-( 1 -hydroxy- 1 -methylpropyl)styrene, 4- octanolylstyrene, 2-methoxystyrene, 4-methoxyst
  • Methyl methacrylate, ethyl methacrylate, acrylonitrile, and vinyl chloride are prefened for use in the present invention because of their lack of odor contribution during cooking at high temperatures. Methyl methacrylate is most prefened.
  • This monomer comprises preferably from about 0.1 to 99% by weight ofthe polymer, more preferably from about 45 to 95% by weight of the polymer, and most preferably from about 60 to 80% by weight ofthe polymer.
  • the latex preferably comprises, based on total monomers, from about 35 to 85% by weight ethyl methacrylate, and more preferably, from about 50 to 70% by weight.
  • the latex preferably comprises from about 45 to 95% by weight acrylonitrile, and more preferably, from about 60 to 80% by weight.
  • the latex preferably comprises from about 40 to 90% by weight vinyl chloride, and more preferably, from about 55 to 75% by weight.
  • the latex of the present invention is made with appropriate colloidal or near colloidal stability by the incorporation of a polymerizable emulsion stabilizer or the inclusion of ionic or steric stabilizers that can be preferentially adsorbed onto the surface ofthe polymer.
  • Suitable polymerizable emulsion stabilizers include mono-vinyl acids such as acrylic acid, methacrylic acid, crotonic acid, citriconic acid, and 2-acrylamidoglycolic acid; divinyl acids such as fumaric acid, maleic acid, vinyl succinic, aconitic acid, and 1,2,3-butenetricarboxylic acid, anhydride or mono-esters for all diacids ofthe variety methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl, 2-ethylhexyl, amyl, and vinyl; vinyl amide functional monomers such as acrylamide, methacrylamide, n-butylacrylamide, t-butylacrylamide, N-dodecylacrylamide, N,N- dibutylacrylamide, morpholylacrylamide, carboxylphenyl methacrylamide, and N- hydroxymethacrylamide; modified st
  • Prefened emulsion stabilizers for use in the present invention include itaconic acid, fumaric acid, acrylic acid, methacrylic acid, acrylamide, 2-hydroxyethyl acrylate, and sulfopropyl methacrylate because of their lack of odor contribution during cooking at high temperatures and the ease with which they produce a stable emulsion during and after polymerization.
  • Itaconic acid is most prefened and is preferably included in an amount from about 0.1 to 5% by weight of the polymer, and more preferably, from about 0.5 to 3% by weight of the polymer. It should be appreciated that the amount of the emulsion stabilizer used may vary depending on the efficacy of the stabilizer.
  • a surface active non-monomeric emulsion stabilizer, or surfactant is optionally added during or prior to polymerization to provide additional stabilization of the latex. It should be appreciated that not every surface active agent is able to equally withstand the final use temperature of the container. Some surfactants may withstand the final use temperature but contribute to polymeric degradation. Prefened surfactants are sodium lauryl sulfate, the disodium salt of dodecyl (sulfophenyoxy) benzene sulfonic acid and analogs (Dowfax® 2A1, commercially available from The Dow Chemical Company) and polyoxyethylene tridecyl ether phosphate (Rhodofac® RS-710, commercially available from Rhone-Poulenc).
  • surfactants are prefened because of their lack of odor contribution during cooking at high temperatures and the ease with which they produce an appropriately stable emulsion during and after polymerization.
  • suitable surfactants are well known in the art and suitable materials can be selected, for example, from among those listed in McCutcheon 's Volume 1: Detergents and Emulsifiers 1998 North American Edition.
  • the latex may optionally include a molecular weight modifier to control the molecular weight of the resulting polymer.
  • the molecular weight modifier may comprise a chain transfer agent or a crosslinking agent.
  • the crosslinking agent acts as a bridge or connector between two or more polymer chains so as to increase the crosslink density of the final polymer, and is typically characterized as being at least di-reactive and possibly multiple reactive.
  • the reaction points can be equivalent (e.g., allyl methacrylate - two vinyl bonds) or dissimilar (e.g., glycidyl methacrylate - one vinyl bond and one epoxy bond).
  • reaction points can be the same as the reactive species ofthe backbone monomers (e.g., the vinyl bonds of a glycol diacrylate in a typical free radical emulsion polymerization). They can also be dissimilar from the reactive species of the backbone monomers so long as the backbone or side chains of the backbone polymer contain sites that, under the appropriate conditions, will be functionally reactive with the crosslinker reactive sites (e.g., the n-methylol methacrylamide hydroxyl reactive site needs a receptive site like a carboxylic acid group).
  • a chain transfer agent acts to reduce the molecular weight of a polymer by transferring the growing end of the polymer chain to a new starting chain during the course of polymerization.
  • a species such as a thio compound with a labile hydrogen or an organic halide with a labile hydrogen.
  • the labile species transfers in order to terminate the growing polymer chain and a new polymer chain begins on the transfer agent from where the labile species was removed.
  • Mercaptans and halides are typically employed as chain transfer agents as the thio-hydrogen or the halogen is particularly labile.
  • Prefened chain transfer agents are t-dodecyl mercaptan and analog alkyl mercaptans as well as ethylthioethylene, bromoform, and carbon tetrachloride.
  • the molecular weight modifier is preferably selected from multifunctional monomers with dissimilar functional groups such as glycidyl methacrylate, glycidyl acrylate, oxybutadiene, n- methylol acrylamide, and n-methylol methacrylamide.
  • multifunctional vinyl monomers such as allyl methacrylate, diallyl phthalate, diallyl fumarate, and diallyl maleate
  • multifunctional acrylate monomers such as trimethylol propane triacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, ethylene glycol diacrylate, 4-methyl-l,4-pentanediol diacrylate, propylene glycol diacrylate, 1 ,6-hexanediol diacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, poly(butanediol) diacrylate, triisopropylene glycol diacrylate, polyethylene glycol diacrylate, trimethylo
  • Glycidyl methacrylate, allyl methacrylate, trimethylol propane triacrylate, n-methylol methacrylamide, and ethyl glycol dimethacrylate are prefened molecular weight modifiers because of their lack of odor contribution during cooking at high temperatures.
  • Glycidyl methacrylate is the most prefened, and preferably comprises from about 0 to 3% by weight ofthe polymer, and more preferably, from about 1 to 2% by weight ofthe polymer.
  • the amount of molecular weight modifier may vary depending on the particular modifier used.
  • the latex also preferably includes an initiator for initiating polymerization.
  • Suitable initiators include inorganic persulfates, azo compounds, organic peroxides, and inorganic peroxides.
  • the prefened initiator for use in the present invention is sodium persulfate run at a reaction temperature of between 70 and 105°C.
  • post-reaction reduction-oxidation additives include antioxidant additives.
  • redox post-reaction reduction-oxidation
  • antioxidant additives include antioxidant additives.
  • the post-reaction redox additives promote the reduction of residual monomer concentration by chemical reaction of species containing vinyl bonds.
  • an oxidizing agent such as t-butyl hydroperoxide is added to the latex followed by a reducing agent such as sodium meta-bisulfite. This combination can effectively reduce low levels of vinyl monomeric species to non-detectable levels.
  • Antioxidants can be added to improve the stability of the polymer by preventing or reducing the rate of free radical generated oxidative degradation.
  • Common antioxidants are frequently based on hinder phenol or amine chemistry. They can be naturally occurring, such as Vitamin E, or they can be synthetically produced. Suitable antioxidants are well known in the art and can be selected, for example, from among those listed in McCutcheon's Volume 2: Functional Materials, 1998 North American Edition. Prefened antioxidants include Vitamin E (d-alpha tocopherol) available from BASF Corporation, Aquamix 494 (blend of a hindered phenol and thioester synergist) available from Harwick Corporation, and FlexolTM Plasticizer EPO (epoxidized soybean oil) available from Union Carbide Corporation.
  • the initiators, stabilizers, and other additives used in the emulsion polymerization may contribute to the specific odor characteristics ofthe resulting polymer.
  • certain initiators will produce a polymer with low or no detectable odor characteristics compared to other initiators (e.g., inorganic persulfates compared to azo compounds).
  • the use of an antioxidant can improve the odor profile of a polymer whose thermal degradation occurs through a free-radical process. A post-reaction reduction- oxidation process to remove odorants may also improve the performance of the latex. Care should be taken that the antioxidant selected does not contribute to thermal decomposition by-products that will produce an offensive odor.
  • the latex composition of the present invention is preferably formed by a conventional emulsion polymerization process in which water is used as a continuous phase.
  • any liquid may be used for the continuous phase as long as the monomers used for the polymerization and the polymers derived from the polymerization are largely, but not completely immiscible in the liquid.
  • less conventional emulsion polymerization processes can be used to produce the latex such as, for example, microemulsion polymerization and inverted phase emulsion polymerization.
  • a surfactant is preferably included to reduce interfacial surface tension, and must be present at a concentration greater than its critical micelle concentration (the concentration in the given medium above which the surfactant will form micelles) in order for an emulsion polymerization to take place.
  • Sodium lauryl sulfate is prefened for use as the micelle forming surfactant.
  • Organic monomers may optionally be present prior to the start of the polymerization, which monomers should be largely immiscible in the continuous medium.
  • a free radical initiator such as sodium persulfate or ammonium persulfate is added.
  • a well controlled level of an organic soluble initiator such as an azo compound (AIBN for example) may be used.
  • the free radical may be generated by any convenient mechanism such as redox conditions or thermal initiation. Where persulfate based initiators are used, thermal initiation in the range of 70 to 110 °C is prefened.
  • the radicals generated by the initiator encounter the monomers to a limited extent as a solubilized species in the aqueous phase and begin a typical stepwise radical polymerization. This is accomplished by the addition of each monomer as a single unit.
  • the radical attaches itself to one end to the monomeric vinyl bond and the reactive radical sight is propagated to the opposite end of the vinyl bond where it is ready to continue the reaction with additional monomeric units.
  • the polymer formed rapidly loses it solubility in the aqueous phase as it grows and eventually precipitates onto a micelle, taking with it a single radical that continues the polymeric growth by addition of monomers found within the swollen micelle. As the monomer is depleted within the now growing particle, it is replaced by monomer found in the monomer droplets. The growing polymer can now be thought of as a latex particle and not a micelle.
  • Stage I only a limited number of micelles will grow into particles. As the particles start to grow, they create surface area that requires surface coverage in order to maintain colloidal stability. The surfactant for this additional coverage is scavenged from micelles that do not contain a growing polymer chain. Stage I ends when the micelle population is completely depleted and only growing polymer and monomer droplets exist in the aqueous system. At this point, the total number of particles in the system is set and cannot increase. This stage typically lasts the first 10 to 20% ofthe total monomer reaction that is going to take place.
  • Monomers may all be present at the beginning of stage I, or they may be added discretely or continuously during stage I. Any reactive vinyl monomer that is largely immiscible in its monomeric and polymeric state may be used in this stage. However, with careful control of concentrations through feed control, monomers that are miscible in water can be used as long as the resulting polymer is not.
  • methyl methacrylate or styrene is preferably used as the stage I monomer.
  • a vinyl monomer that contributes to particle stability by being both polymerizable and surface active may be employed.
  • a vinyl acid such as acrylic or itaconic acid is prefened for use in the present invention.
  • additives may be included. Additional surfactants of the same or a different type can be present or added to the system. Chelating agents can be present or added to the system to reduce fugitive metals. If persulfate based initiators are used, a small amount of base may be added to the system to compensate for low levels of sulfuric acid generated by hydrolytic degradation.
  • stage II ofthe polymerization the particles started in stage I continue to grow. As the particles grow, the monomer droplets containing reserves of monomers continue to shrink. Stage II is complete when the monomer droplets are completely consumed. Typically, this will last from around 10 to 20% ofthe total monomer conversion of the reaction to 60 to 90% of the total monomer conversion of the reaction. During this phase of the reaction, the total number of latex partricles is fixed and only the size of the particles change.
  • stage II a wide variety of vinyl monomers may be used for this polymerization. Any reactive vinyl monomer that is largely immiscible in its monomeric and polymeric state may be used. With careful control of concentrations through feed control, monomers that are miscible in water can be used as long as the resulting polymer is not. Additionally, a vinyl monomer that contributes to particle stability by being both polymerizable and surface active may be employed. Most prefened is a vinyl acid such as acrylic or itaconic acid. In the present invention, two options are available for stage II polymerization: unseeded and seeded. In the "unseeded" approach, the stage I monomer is preferably a combination of methyl methacrylate and methyl acrylate. The process starts as described in stage I and proceeds with essentially the same monomer combination through stage II.
  • a relatively small styrene or other polymerized vinyl monomer particle is made in stage I and completed through stages II and III.
  • This polystyrene latex is used to begin a new stage II reaction with a different set of monomers, preferably methyl methacrylate and methyl acrylate.
  • a carefully calculated and nanowly distributed final particle size can be achieved that would otherwise be very difficult to obtain.
  • the styrene particle which is used is relatively small (on the order of 100 to 300 A in diameter) compared to the final desired particle diameter of 500 to 50,000 A in diameter.
  • stage II starts with the number of particles already fixed and growth occurs through monomer droplet depletion.
  • itaconic acid is also preferably employed to increase the particle stability by the addition of a surface-active polymerizable species.
  • An initiator must be added to the system to continue the polymerization.
  • Other additives may also be included such as surfactants, chelating agents, or bases as described above.
  • the morphological architecture ofthe polymer can be specifically tailored or modified by changing the composition of the monomers present and available for reaction during the course ofthe polymerization. This results in phases of polymer generation with dissimilar composition. In its most mild form, this results in minor compositional drift during the polymerization. In its more extreme form, the monomers used can be completely changed and a polymer can be made with discrete blocks of dissimilar monomer units and phase separation into two or more distinct polymer regimes within each particle.
  • stage III the monomer droplets are depleted and the remainder ofthe reaction occurs within the polymer particle. As such, very little change in particle size occurs, but the molecular weight ofthe particle continues to increase.
  • This stage begins at around 60-90% ofthe total monomer conversion ofthe system and continues to 100% ofthe total monomer conversion of the system. Termination can occur through coupling or disproportionation.
  • the monomers remain the same during stage III and residual analysis shows very high overall monomeric conversions, in excess of 99%.
  • the polymer within a given particle is essentially a single molecule and is, accordingly, of very high molecular weight.
  • the polymer typically exists with a level of internal crosslinking, the degree of which is refened to as the crosslink density ofthe polymer.
  • a molecular weight modifier is preferably added during all three stages of polymerization.
  • the molecular weight modifier may comprise chain transfer agents or crosslinking agents as described above.
  • Low level residual monomers and latent impurities may be removed by a number of reaction or distillation techniques. For example, redox of somewhat water soluble vinyl monomers can be a useful reaction. Vacuum or steam aided distillation of the emulsion polymer can selectively remove organic species of appreciable vapor pressure.
  • the emulsion polymer may be filtered to remove any gross sized coagulate present.
  • the pH may also be adjusted with acids or bases to better suit the desired end use.
  • a biostatic agent may be added to help prevent bacterial growth, and other additives may be added such as surfactants, defoamers, dispersants, surface spreading agents, or stabilizers. If these are organic species, they may exist as liquid-liquid emulsions in the water independent ofthe polymerized solid particles, or the organic liquid may partition into the particles. If these are water soluble species, they may exist as independent dissolved species or they may be associated with the surface ofthe polymerized particles.
  • the resulting latex functions as a good binder for the highly filled composite, imparting strength and stiffness to the formed article.
  • the latex used in the present invention is unique in that it acts as a good binder and is thermally stable such that the resulting article can be used in high temperature applications such as food preparation process, either to cook or reheat food at oven temperature up to about 600°F without the generation of an odor resulting from polymeric degradation. Polymers typically experience degradation upon exposure to high temperatures which leads to the release of odor causing agents.
  • an article can be produced which is thermally stable at oven temperatures as high as 600 S F.
  • a dispersed polymer is any polymer present as the discrete phase of a multi-phase heterogeneous system with a continuous medium.
  • the degree of dispersion refers to how finely the non-continuous polymer phase is divided and distributed throughout the continuous phase.
  • the continuous medium is limited to aqueous systems, and the degree of dispersion must be adequate to provide sufficient polymer surface area to allow the polymer to function as a binder in the filled composite material.
  • dispersed polymers must be largely or completely insoluble in water.
  • the polymer can be selected from those polymers that require mechanical energy to be dispersed or those polymers that are self-dispersing.
  • the polymer can be either synthetically produced, naturally occurring, or a derivative of a naturally occurring polymer. See D.H. Everett, Basic Principles or Colloidal Science, Royal Society of Chemistry, 1989.
  • Mechanically dispersed polymers can also be made by conventional techniques to emulsify polymers in the presence of an appropriate level of water and emulsifier to form a mechanical dispersion. Examples of such techniques are set forth in Pate et al., U.S. Patent No. 5,688,842. Such mechanical dispersion polymers are generally greater in particle size than latexes and are somewhat less colloidally stable.
  • Suitable polymers include polyethylene or polyethylene copolymers, polypropylene, polyethylene terephthalate, polyurethanes, poly(thermoplastic epoxies), poly(lactic acid) and others. When dispersed to a particle size range that is colloidally or nearly colloidally stable, these polymers can behave as latexes and can be incorporated into the composite material formulation as a binder.
  • self dispersing polymer any polymer that can form a heterogeneous dispersion without the input of mechanical energy. This dispersion can be accomplished through chemical or other means.
  • An example of a self-dispersing latex would be a poly(ethylene-acrylic acid) copolymer with an appropriate molecular weight to transition from solution to dispersion by changing the aqueous pH. Primacor® (available from The Dow Chemical Company) is one example of such a polymer.
  • binders can disperse in the aqueous system from which the article is formed. They can act to provide binding strength just as a synthetic latex or mechanically dispersed polymer would.
  • Dispersible natural polymers and their derivatives fall into four broad categories and for the purpose of this invention are limited to those binders within each category that are not excessively water soluble at the use conditions, i.e., binders which are sufficiently water insoluble so that they can perform properly as a binder in the flocculated system.
  • binders which are sufficiently water insoluble so that they can perform properly as a binder in the flocculated system.
  • These groups include cellulose ethers (such as methyl and ethyl cellulose ethers), proteins (such as corn zein or collagen), starches (such as potato starch or dextrin), and other polysacchararides (such as guar gum).
  • the composite formulation also preferably includes a colloidal destabilization additive or additives which function to destabilize the latex and aid in its binding ofthe filler and fibers into a larger aggregate structure.
  • the colloidal destabilization additives modify the electric charge of the fiber such that the filler and binder will precipitate onto the fiber.
  • This process is generally refened to as flocculation, which involves the formation of larger particles of a solid phase dispersed into a solution by gathering of smaller particles into groups.
  • the groups of particles are in effect discrete clumps which are sufficiently large to resist passing through the openings of the porous support surface on which they must be retained.
  • Flocculation is caused by chemically overcoming the intrinsic repulsive forces that exist to keep a heterogeneous solution in its most dispersed state. These forces include electrostatic, solvation, and steric repulsion. To overcome these forces and create the larger grouped particles, several mechanisms can be employed.
  • the process of flocculation can be achieved by: 1 ) double- layer compression, 2) specific ion adsorption, 3) sweep flocculation, 4) polymer charge patch, and 5) polymer bridge (Kirk-Othmer Encyclopedia of Chemical Technology, 3 rd Ed., Vol. 10, 1980).
  • Components which make use of the first three mechanisms are typically refened to as cationic sources.
  • Components which make use ofthe last two mechanisms are typically refened to as flocculants.
  • Many components can contribute to one or more ofthe first three mechanisms and one or both ofthe last two mechanisms. Accordingly, for purposes of the present invention, a single component may function as both a cationic source and a flocculant.
  • a suitable flocculant for use in the present invention includes any material which can act by either a general patch accumulation effect or a bridging activity to chemically render larger particles from the aggregation of smaller dispersed particles.
  • Flocculants for use in the present invention may be cationic, anionic or nonionic, and may be natural or synthetic.
  • the activity of the flocculant is pH dependent and can be activated in certain ranges. Activity and degree of activity for polymeric materials may be largely dependent on achieving an appropriate molecular weight range. Polymers outside the molecular weight range may have the conect composition and still exhibit no activity as a flocculant.
  • Useful cationic flocculants grouped by chemical class include cationic amine polymer- epichlorohydrin adducts, poly(alkylene polyamines) (polyethyleneimine [PEI]), poly(hydroxylalkylene polyamines), quaternary polyamines, polyaziridines, cationic cyanamide derivatives, cationic carbamoyl polymers (polyacrylamide reacted with formaldehyde and dimethylamine), polycyclic amine (poly(2-vinylimidazoline), vinyl addition polymers (diallyldimethylammoniurn chloride), acrylic and methacrylic ester polymers, and N- (dialkylaminoalkyl)acrylamide polymers.
  • Many other cationic polyelectrolytes are useful such as cationic starch derivatives and cationic polysaccharide derivatives (e.g. chitosan).
  • Useful anionic flocculants grouped by chemical class include polymers containing carboxyl groups (e.g. polyacrylic, polyacrylic-co-acrylamide, etc.), polymers containing sulfonic acid groups (e.g. polyethylenesufonic acid), anionic starch derivatives, and anionic polysaccharide derivatives (e.g. Xanthan), colloidal silica and bentonite clays.
  • carboxyl groups e.g. polyacrylic, polyacrylic-co-acrylamide, etc.
  • polymers containing sulfonic acid groups e.g. polyethylenesufonic acid
  • anionic starch derivatives e.g. Xanthan
  • colloidal silica and bentonite clays e.g. Xanthan
  • Useful nonionic flocculants grouped by chemical class include polyacrylamide polymers and copolymers, poly(ethylene oxide) polymers and copolymers, poly(vinylpynolidone) polymers and copolymers, starches, polysaccharides, and colloidal protein (e.g. gelatin or animal glue).
  • Suitable commercially available flocculants include poly(ethyleneamine), poly(2- hydroxypropyl- 1 -N-methylammonium chloride), poly(2-hydroxypropyl- 1 , 1 ,-N-dimethylammonium chloride), poly[N-dimethylaminomethyl)-acrylamide- ⁇ ], poly(2-vinylimidazolinum bisulfate), poly(diallyldimethylammonium chloride), poly(N,N-dimethylaminoethyl methacrylate), poly[N- (dimethylaminopropyl)-methacrylamide], poly(sodium or ammonium acrylate), poly(sodium styrenesulfonate), polyacrylamide, poly(ethylene oxide), poly(vinylpynolidone), starches (amylose and or amylopectin), starch derivatives, polysaccharides (e.g., guar gum, alginic acid, sodium alginate, chitos
  • Suitable cationic sources for use in the composite formulation include metals, metal salts, hydrolyzed metal ions, low molecular weight, highly charged polymers, or any other suitable materials which function to destabilize the electrostatic repulsive forces that stabilize the dispersed system. It should be noted that while in some instances, cationic sources can cause flocculation, they are typically not capable of sufficiently flocculating the dispersed composite materials when used alone. However, the use of a cationic source in combination with a flocculant aids in reducing the amount of flocculant needed to completely flocculate the dispersed composite materials.
  • Suitable cationic sources include, by way of example, aluminum, aluminum hydroxide, supersaturated aluminum hydroxide, sodium aluminate, aluminum sulfate, alum, hydrolyzed aluminum chloride ion, ferric hydroxide, supersaturated ferric hydroxide, ferric sulfate, ferric chloride, fenous sulfate, magnesium bicarbonate, lime (calcium or calcium/magnesium oxide, dolomitic lime), sodium silicate, hydrolyzed derivatives of silicon, bentonite clay, common dispersants (tetrasodium pyrophosphate, tetrapotassium pyrophosphate, sodium hexametaphosphate, appropriate molecular weight polyacrylic acid and polyacrylic acid salts, etc.), cationic amine polymer-epichlorohydrin adducts, poly(alkylene polyamines), (e.g.
  • polyethyleneimine poly(hydroxylalkylene polyamines), quaternary polyamines-vinyl addition polymers (e.g. diallyldimethylammomum chloride).
  • quaternary polyamines-vinyl addition polymers e.g. diallyldimethylammomum chloride.
  • Many other cationic polyelectrolytes are also suitable for use. It should also be appreciated that not every cationic source is able to equally withstand the final use temperature ofthe article. Some cationic sources may be able to withstand the final use temperature but contribute to polymeric degradation.
  • latex itself may be modified to be cationic such that it performs the function of binding the filler, fiber and latex without the need for a colloidal destabilization additive.
  • the composite formulation may also optionally include additives such as pigments or dyes, optical brighteners, sizing agents, antioxidants, UV stabilizers, impact modifiers, dry strength additives, wet strength additives, defoamers, antimicrobials, slimicides, mildicides and fungicides.
  • additives such as pigments or dyes, optical brighteners, sizing agents, antioxidants, UV stabilizers, impact modifiers, dry strength additives, wet strength additives, defoamers, antimicrobials, slimicides, mildicides and fungicides.
  • the filled composite material further comprises from about 0.1 to 10% by weight of a coloring agent such as carbon black. It should be appreciated that in some instances, the filler can also function as a coloring agent.
  • Fig. 1 One prefened process for making the container ofthe present invention is illustrated in Fig. 1.
  • This process is carried out using an adaptation of a traditional fine pulp molding process in which a portion 10 of the composite materials (filler, fiber, binder, optional cationic source and any additives such as colorants, antioxidants, anti-microbial agents, etc.) are mixed in a mix tank 12.
  • the materials are mixed as a dilute mixture in water at about 1 to 10% solids based on total wet weight.
  • the materials can be added in any order with the exception ofthe flocculating agent, which is preferably added last.
  • the majority of the water is placed in the tank, followed by the fibers, fillers, cationic source, and binder.
  • a flocculant and/or cationic source 16 is prepared for addition and stored. While a single tank is illustrated herein, it should be appreciated that multiple tanks may be necessary to achieve the conect degree of flocculation.
  • the mixed materials 10 are then placed in a flocculation tank 18 and the materials are flocculated by the batch-wise addition of flocculant 16 from the tank 14. Additional water can be added at this step to decrease the material solids to between 0.1 and 5% solids based on total wet weight.
  • the flocculated material 20 is then transfened to a formation tank 22.
  • the flocculation tank 18 is preferably agitated by a low shear, low efficiency agitator such as an A310 type agitator which includes several vertically fixed profiled baffles (not shown).
  • the baffles and agitator keep the flocculated material dispersed and prevent settling without imparting a level of shear that would degrade the flocculated material structure.
  • the baffles are designed to provide low flow resistance and axial mixing.
  • the batch flocculation tank 18 is operated so that a desired amount of flocculated material 20 is made periodically and sent to the formation tank 22 to keep the formation tank level above a minimum level but below a maximum level. Minimum shear is desirable during the flocculation and transfer process. Accordingly, it is preferable to transfer the flocculated material 20 from flocculation tank 18 to the formation tank 22 by means of gravity feed. This requires that the flocculation tank 18 be located physically above the formation tank 22 as shown.
  • the mixed materials may be run through one or more step tanks. Flocculant is continuously added to the step tanks from storage tanks. Additional water can also be added at this time to decrease the material solids to between 0.1 and 5% solids based on total wet weight. The resulting flocculated material is then transfened to the formation tank.
  • the step tanks are essentially equivalent in design and include low shear, low efficiency agitators such as an A310 type agitator.
  • the mixed material enters the step tanks through ports located in the top ofthe tanks such that the mixed material is preferably introduced at the tip of the agitator blade.
  • the material preferably drops down in the vessel and is processed around an interior draft tube which helps to determine the flow path and average residence time of the flocculated material.
  • the draft tube includes low shear axial flow profiled baffles.
  • the tanks also include profiled baffles. After the flocculated material has moved down and around the draft tube, it rises in an annular ring between the draft tube exterior wall and the tank interior wall until it reaches an overflow outlet which controls the height ofthe flocculated material.
  • the draft tube functions to minimize the average residence time of the material in the step tank while maintaining a low shear environment.
  • the draft tube is not critical to the function of the step tank and may be removed in some or all of the step tanks depending on the desired flocculated particle size and its resistance to shear degradation. This continuous system minimizes the total shear the flocculated material will receive before it is formed into an article.
  • the rate of flocculated material production in the continuous step tank system is controlled to maintain a constant level of flocculated material in the formation tank.
  • the composite mixture can be delivered directly to a vented formation tool which is a porous shaped tool which may be covered with a screen of fine mesh on the outside.
  • the mixture is delivered in amounts just necessary for formation of a single part.
  • the material would be flocculated while being delivered to the formation tool by flocculant addition and in-line mixing using a device such as a static line mixer.
  • the formation tank can be removed and the flocculated composite material shear history is held to an absolute minimum.
  • the flocculated material composite material 20 in the formation tank 22 is maintained at around 0.1 to 5% solids based on total wet weight.
  • a vented formation tool 24 is then placed into the mixture.
  • the tool 24 is a porous tool which may be covered with a screen of fine mesh on the outside. It is mounted on a platen 26 and is adapted to have a vacuum drawn through it such that it pulls water from the mixture 20 through the tool and into a vacuum system (not shown). As water is drawn through the porous formation tool, a layer of flocculated material 20' is retained. After the material 20' has built up on the tool 24 to the extent desired, the tool is removed from the mixture. The amount of material retained on the tool is dependent on the length of time the vacuum is employed, the strength ofthe vacuum, the concentration of the flocculated mixture, and the nature ofthe strength of the flocculated materials and their ability to withstand shear. Each of these variables can be independently manipulated to control deposition weight.
  • the platen may hold any number of tools that can be geometrically fitted into the available area. In a typical system, the number of tools per platen should be maximized to operate at the greatest efficiency.
  • the tool can be mated to a vented transfer tool 28 positioned on a receiving platen 30. Once mated, vacuum can be applied to both tools 24, 28 to further decrease the water content of the formed article 20'. Heat can also be applied through the top and bottom platens 26,30 and/or tools 24,28 to help drive off water and dry the article. While Fig.
  • the article may be transfened by means of additional transfer tools mounted on additional platens such that the article is moved to additional vented drying tools in series. This can be done to decrease the time each article spends drying on each tool by spreading this time out over several stations, resulting in increased output. It should be apparent that the independent drying and transfer tools can be operated at different temperatures to enhance the rate at which water is removed without damaging the article by drying too rapidly or with too much heat.
  • the drying process results in an article having the desired shape and size.
  • the article shown in the drawing figures is in the form of a substantially circular container 70 which is appropriate for cooking. It should be understood that the shape ofthe formation, transfer and drying tools employed controls the shape ofthe container.
  • the article may be pressed at any point during the formation or drying step to increase surface smoothness or to densify the material. Pressing can also be performed offline after the formation is complete, either on the dried article or on a remoistened article. Pressing can be performed at room temperature or at elevated temperatures.
  • FIG. 2 An alternative process for making the container is illustrated in Fig. 2 which utilizes an adaptation of a traditional thin wall pulp molding process.
  • the initial process is identical to the process illustrated in Fig. 1, i.e., the composite materials 10 are mixed and placed in the tank 12, then transfened to flocculation tank 18 in which flocculant 16 is added from tank 14 to obtain flocculated material 20.
  • the mixed material may also be run through step tanks as described above with reference to Fig. 1 ).
  • a vented formation tool 32 is placed into the flocculated material mixture 20.
  • the tool 32 is porous and may be covered with a screen of fine mesh on the outside.
  • Tool 32 is mounted on a platen 34 and is adapted to have vacuum drawn through it as described above.
  • the composite mixture can be delivered directly to the formation tool in an amount appropriate for the formation of a single part.
  • the material 20 is formed on the formation tool 32, it is transfened to a vented transfer tool 36 positioned on a second platen 38.
  • the transfer tool is a mated match for formation tool 32 but the tools are not closed together with pressure. Vacuum is drawn through the formation and transfer tools 32, 36 and heat may be additionally employed to decrease the water content of the resulting article 20'. A substantial portion of the water is removed by vacuum induced water drainage. This minimizes the energy required to complete the drying process.
  • article 20' After article 20' is sufficiently dry to retain its shape, it is transfened between two pressing tools 40, 42 mounted on two separate platens 46, 48. Pressure is applied to both platens so that the tools 40,42 are forced together.
  • This pressing step may be followed by the final drying step. If the drying step follows pressing, the tools must be vented to allow for the evolution of steam during the pressing process. Also, to aid in the forming and drying process, the press tools and/or platens can be heated. If desired, the article 20' may be dried prior to pressing. In this case, the tools do not need to be vented. The article 20' may be dried in any industrial oven 50 until it reaches the desired dryness.
  • Suitable ovens include gas or electric forced air impingement ovens or any other type of commercially available drying oven.
  • the process results in a shaped article, which in the embodiment shown, is in the form of a substantially circular container 70 which is appropriate for cooking at elevated temperatures.
  • Another prefened process for making the article ofthe present invention is illustrated in
  • a portion 10 of the composite materials are mixed in a mix tank 12.
  • the materials are mixed as a dilute mixture in water at about 1 to 10% solids based on the total wet weight.
  • the materials can be added in any order with the exception of the flocculating agent, which is preferably added last.
  • the majority of the water is placed in the tank, followed by the fibers, fillers, cationic source, and binder. Any other additives or fillers may then be added prior to or after flocculation occurs.
  • a flocculant and or cationic source 16 is prepared for addition and stored. While a single tank is illustrated herein, it should be appreciated that multiple tanks may be necessary to achieve the conect degree of flocculation.
  • the mixed materials 10 are placed in the flocculation tank 18 and the materials are flocculated by the batch- wise addition of flocculant 16 from tank 14. Additional water can be added at this step to decrease the material solids to between 0.1 and 5% solids based on total wet weight.
  • the flocculated material 20 is then transfened to a formation tank 22.
  • the flocculation tank 18 is preferably agitated by a low shear, low efficiency agitator such as an A310 type agitator which includes several vertically fixed profiled baffles (not shown).
  • a low shear, low efficiency agitator such as an A310 type agitator which includes several vertically fixed profiled baffles (not shown).
  • the batch flocculation tank 18 is operated so that a desired amount of flocculated material
  • the flocculated material 20 is made periodically and sent to the formation tank 22 to keep the formation tank level above a minimum level but below a maximum level. Minimum shear is desirable during the flocculation and transfer process. Accordingly, it is preferable to transfer the flocculated material 20 from flocculation tank 18 to the formation tank 22 by means of gravity feed. This requires that the flocculation tank 18 be located physically above the formation tank 22 as shown.
  • the mixed materials 10 may be run through one or more step tanks as described above with regard to the pulp molding process. Additional water can also be added at this time to decrease the material solids to between 0.1 and 5% solids based on total wet weight. The resulting flocculated material is then transfened to the formation tank. The rate of flocculated material production in the continuous step tank system is controlled to maintain a constant level of flocculated material in the formation tank 22.
  • the flocculated material 20 is formed into a sheet by placing the flocculated composite mixture on a moving wire screen 124 from the formation tank 22.
  • the material is evenly distributed over a wide screen (up to or more than 12 feet wide) by the use of a flowspreader or other similar apparatus, and water is removed from the forming sheet at 28.
  • This apparatus is similar to a Fourdrinier paper formation system. As with a Fourdrinier system, the water is removed from the sheet by the use of appropriate placed hydrofoils, table rolls, and vacuum boxes. Additional apparatus such as a breast roll, rubber deckle, and dandy rolls may also be used. It should be understood that any appropriate paper formation system could be used as long as it can be adapted to handle the highly filled composite material of the present invention.
  • the sheet formation step a substantial portion of water is removed from the composite material. Once it is sufficiently dry to retain its shape and allow handling, the sheet 20' is separated from the wire screen at couch roll 126' and opposing lump breaker roll 126. At this point the sheet has sufficient strength to be processed as a freestanding sheet. No mechanical assistance is required to transport the sheet other than to pull it through the finishing path along which it will travel.
  • the sheet 20' may simply be removed from the wire or it can be lightly or significantly pressed by couch roll 126' and lump breaker rolls 126 or by additional process rolls up or downstream of the couch roll.
  • This pressing contributes to surface smoothness and densification of the sheet.
  • the increase in speed should be directly related to the decrease in thickness and all other steps in the process should accommodate this rate change.
  • the sheet 20' can be dried. As shown in Fig. 3, a series of three drying cylinders 31, 32, 33 are utilized for drying. It should be understood that the number of drying cylinders may vary based on the wetness ofthe material.
  • the cylinders may be heated in any conventional way, such as steam and hot oil.
  • the composite material sheet 20' is typically in contact with the drying cylinder(s).
  • a felt sheet (not shown) may be placed behind the composite material 10 to force greater contact as the sheet passes over the drying cylinders. The felt must allow for water transport so that it does not retard drying. Two felt loops can be utilized in this fashion, one for the top set of rollers and one for the bottom set of rollers.
  • the composite sheet 20' is then preferably pressed into a geometric shape by a single mated tool press 50 that employs pressure against upper and lower platens 57, 59 which include a male tool 52 and a matched female tool 51.
  • a single mated tool press 50 that employs pressure against upper and lower platens 57, 59 which include a male tool 52 and a matched female tool 51.
  • the tools will mate and force the material into the tool shapes to form an article 68. Care must be taken not to tear the material during the pressing step. If the pressing is done too rapidly, or the size of the change exceeds the limitations of the specific formulation in use, the resulting article will be damaged.
  • the tools may be heated to aid in formation.
  • the composite sheet can be rolled or cut into discrete segments and pressed at a convenient time and location. It should be understood that the shape ofthe tools controls the shape ofthe resulting article. While Fig. 3 illustrates a single tool set being used to press a single article, it should be appreciated that multiple tools could be employed to create multiple articles with each compression.
  • the article 68 is preferably cut from the continuous sheet using a single cutting unit 60 to form a finished article, which in the embodiment shown, is in the form of a container 70.
  • This unit descends onto the article 68 and cuts using any appropriate die cutting system around the perimeter ofthe container leaving a clean and aesthetically pleasing edge.
  • the article 70 is removed from the scrap composite material sheet so that it can be sorted, stacked, wrapped and/or packed for shipment. It should be understood that the article can be removed by a number of techniques.
  • the scrap composite material can be accumulated for recycling or discarded as appropriate.
  • An alternative method of the present invention is illustrated in Fig. 4 in which the article 68 is pressed prior to drying, i.e., the article is pressed in a moist condition.
  • the materials are mixed and flocculated, and the flocculated mixture 20 is placed on a moving wire screen 124 as described above.
  • the moist composite sheet 20' is removed from the wire and pressed in a tool 50 to form a shaped article 68.
  • the article 68 is then dried in any industrial oven device 35 until it reaches the desired dryness. This can be a gas or electric forced air impingement oven or any other type of commercially available drying oven.
  • the drying step does not have to immediately follow the pressing step. Drying can be performed after cutting and/or after barrier application if an appropriate adhesive is used.
  • the shaped article is cut as described above. In any ofthe methods utilized to form the article, one or more optional barrier layers can be applied on or incorporated into the article.
  • the barrier layer or layers function to protect food in the container from gas and vapor exchanges within the environment which could lead to loss of freshness or the introduction of an undesirable odor or taste.
  • the barrier layer may also function to prevent oil or grease in foods from penetrating the container as well as providing a release layer for removing food from the container without sticking.
  • the barrier layer is preferably laminated to the article.
  • the barrier layer may be applied by coating, painting, powder coating, spraying or dipping techniques.
  • the method of applying the barrier layer is determined by several factors including the nature ofthe barrier material, the form ofthe article, its thickness, sealing capability and acceptance of printing inks.
  • Suitable polymers which may be used to form the barrier layer include ethylene-vinyl alcohol copolymers, nitrile resins, aliphatic and aromatic polyamides, polyethyl pentene, polyethylene terephthalate, poly(lactic acid), polysiloxane, polytetrafluoroethylene, polyvinyl chloride, polyvinylidine chloride and tortuous path blends or multiple layers of barrier polymers and structured resins such as nitrile resins, polycarbonates, polyethylene terephthalate copolymers, polyolefms such as polyethylene, polypropylene, or polytetrafluoroethylene as well as polystyrene and polyvinyl chloride, polybutylene terephthalate, polysulfones, polyethersulfones, polysiloxanes, silicones, polyketones, liquid crystal polymers, polyphthalamide, latexes (polymerized or mechanically dispersed), and cellulose ethers (with or without
  • a prefened barrier layer is amorphous polyethylene terephthalate film.
  • the barrier layer may also be treated or coated prior to lamination to the container with a surface modifier in order to impart additional properties to the barrier polymer.
  • the surface modifier may be used to facilitate the mechanical handling of the barrier layer, to induce a polar surface for ease of printing, to color the barrier layer, to harden the surface so as to provide scratch resistance, or to enhance adhesion ofthe laminate to the substrate.
  • Modifiers such as silane coupling agents and hot-melt adhesives can be coated onto the barrier layer.
  • FIG. 5 A representative shaped article prepared by the method of the present invention is illustrated in Fig. 5.
  • the article is in the form of a container 70 which is configured to include a floor 80 and surrounding side wall 82 defining an opening for containing food.
  • a flange or peripheral edge portion 84 is preferably formed on the top edge of the sidewall.
  • the container also preferably includes a lid 90 which is adapted to be fitted onto the peripheral edge of the sidewall.
  • the lid of the container may be made by the same methods described above with regard to the container, or it may be made from materials such as paper, paperboard, pulp molded paper or formed or foamed thermoplastics (if it does not need to withstand the same thermal conditions as the container).
  • the lid may be designed to screw onto the container, or it may be designed to snap on or form an interlocking or continuous seal with the container.
  • the lid may also be embossed or provided with printed indicia.
  • the container may also be provided with embossed or printed indicia as desired.
  • the container and lid may be formed in a number of different configurations.
  • the container may also include a barrier layer 92 as shown in Fig. 6. As shown in Fig.
  • the article 70 when used as an ovenable food container, it also preferably includes raised areas 94 which aid in food release as well as maintain the food above the level of any moisture, grease, or oils which may drain from the food during cooking. Such raised areas also allow heat to crisp and dry the bottom ofthe food being heated, e.g., pizza crust.
  • the container may be used to store food which is added to the container.
  • the container may be used to store food which is added to the container and refrigerated and/or frozen until such time as it is ready to be cooked.
  • the container may be used as a pizza pan in which dough may be added to the container, sealed with the lid, and frozen, and then delivered to a customer where the dough is thawed, ingredients are added, and a pizza is then cooked within the same container, and delivered to a consumer with the lid in place.
  • the container may also be used for other applications such as packaging and heating or cooking a variety of frozen foods.
  • the design and composition ofthe container and lid provides good thermal insulation properties to maintain heat of the cooked food, e.g., during delivery.
  • the lid may be formed from a variety of materials, the use of a lid formed from the composite material or from pulp-molded paper allows controllable abso ⁇ tion of moisture from chilled or heated food, i.e., no appreciable condensation.
  • the compressed container bottom allows better heat conduction in an oven than containers which have not been formed from compressed materials.
  • the container exhibits a low thermal heat transfer rate which allows manual handling of the hot container.
  • the container and lid may be configured to provide a number of other desirable features.
  • the lid may be designed to interlock with the bottom of a second covered pan such that the pans and lids may be stacked for storage or transport.
  • the lid may also be designed to be removed, inverted, and fitted underneath the container so as to function as a trivet after the food is cooked.
  • the container may be configured in a number of other shapes and sizes, for example, the container may be rectangular in shape and may include handles on opposite sides to aid in transport of the container, e.g. from an oven.
  • the container and lid may be formed in a number of other different configurations as
  • the testing temperature and time were chosen to best simulate the interfacial temperature between the container and a food item at normal and extreme temperatures during an actual cooking cycle in an impinger type forced air oven set at varying temperatures up to 600°F.
  • material formulations were examined. These included various 1) fillers, 2) synthetic fibers, 3) cellulose fibers, 4) binders (both binder classifications and within the synthetic latexes class; variations of hard and soft monomers, emulsion stabilizers, molecular weight control agents, reaction conditions, and other additives), 5) flocculants, 6) cationic sources, 7) colorants, and 8) several miscellaneous additives.
  • the combinations were compared statistically to determine which combinations had acceptable odor profiles for cooking use conditions.
  • Latex samples were prepared in accordance with the present invention and cast into films, dried and collected for thermal conditioning and organoleptic evaluation.
  • a composite material sample was made in sufficient quantity for thermal conditioning and organoleptic evaluation.
  • Composite material samples were made from the various combinations described above in sufficient quantity for thermal conditioning and organoleptic evaluation. Samples were formed using a lab-sized handsheet formation box typically used to make single sheets of pulp or filled pulp paper. The formula used as the basis for testing is shown below in Table 1.
  • the components were mixed in the following order: water, cellulose, polyester, calcium carbonate, Kymene® 736, sodium carbonate, binder, and alum.
  • the components were then flocculated with the BMA 780 and MX-10.
  • the flocculated mixture was placed in a headbox and diluted with water.
  • the water was drained through a fresh screen leaving the solids of the mixture on the screen surface.
  • the screen and formulation were removed from the headbox and placed between pulp testing blotting paper which complied with TAPPI specification T205 om88.
  • the "sandwich” was then placed on a press platen and pressed at approximately 100 psi for about 5 to 10 seconds.
  • the resulting sheet was then removed and placed between 4 sheets of blotter paper (two above and two below sheet).
  • the sheet was re-pressed at 1600 psi for 15 to 30 seconds.
  • the pressed sheet was then placed on an Emerson dryer and dried for about 20 minutes, turning the sheet over 2-3 times during drying. After drying, the sheet was cut in half, weighed, placed in a pre-washed glass jar, and set aside for further testing.
  • the thermal testing cycle was made to best approximate the thermal cycle of food cooked in an air impingement track oven.
  • the testing conditions included a normal cooking cycle and an extreme cooking cycle.
  • the oven was set to a temperature of about 430-465°F, but it should be noted that the food and the container in contact with the food did not reach this temperature.
  • Studies of actual oven use during cooking show that an interface temperature of about 350°F would be typical of this type of oven setting. Accordingly, a temperature of 350°F was adopted as the appropriate normal cooking thermal cycle condition.
  • the food cooked for testing pu ⁇ oses was a thick crust pizza.
  • an air impingement oven may be set as high as 550°F and internal temperatures at hot spots are reported to reach as high as 600°F if the oven is under heavy load.
  • the interfacial temperature may be 50 to 75°F higher than under normal conditions.
  • An excursion temperature of 425°F was adopted as the appropriate cooking thermal cycle condition.
  • Cooking food at these conditions requires significantly less than 10 minutes when using a high velocity air impingement oven such as that used to cook pizza. Under normal conditions, a pizza would be cooked in approximately 7 minutes. This would include browning of the crust, simulating a baking process. Accordingly, 7 minutes was adopted as the processing time for the samples. It should be appreciated that, given the size of the samples examined, these conditions are more severe than an actual cooking article would experience in use. The results were accordingly examined as acceptable, likely acceptable, or unacceptable in a real application.
  • a Model 1301 Lincoln Impingement Conveyor Oven was preheated to the desired temperature of either 350°F or 425°F and allowed to come to temperature for at least 90 minutes.
  • Samples ofthe resin and composite were placed into individual sample pre-washed flint glass jars and their weight recorded. Samples weighing 0.500 ⁇ 0.010 grams for resin samples and 3.0 +0.100 grams for filled composite samples were used.
  • Aluminum foil wiped with clean cheese-cloth was used to cover the jars by removing the jar lid, placing an aluminum foil square over the jar, tightening the lid over the aluminum foil, and then removing the lid.
  • Each jar was placed on its side on the track ofthe oven and pulled into the oven by the track.
  • Each sample was allowed to heat for 3.5 minutes before placing the next sample on the oven track.
  • the samples were then placed upright on a flat surface and allowed to cool to room temperature for about 45 minutes.
  • the lids were then replaced on the jars and the samples were subjected to organoleptic testing within 6 to 9 days after exposure to thermal cycling.
  • organoleptic testing was conducted by an organoleptic testing panel consisting of 25 trained panelists with noted olfactory sensitivity. Prior to the beginning of testing, an orientation was conducted to establish a baseline of agreed upon odor intensities.
  • the samples were distributed to the panelists at the same time, and were given to the panelists in a random order.
  • the samples were examined using the following method:
  • the panelists were oriented to the grape juice reference samples by sensory testing in series. Then, prior to testing, the sample jar was shaken, and the lid unscrewed such that the lid was lifted on one side but remained in contact with the jar on the other side.
  • Several short "bunny" sniffs were taken of each sample, an impression of the overall intensity ofthe sample was made and evaluated on a 10-point scale (1-10) using the grape juice references. A rating of 11 was used for any sample that had an intensity greater than the highest reference intensity of 10.
  • Each component chosen for examination was selected in part based on its ability to represent a general class of components. As such, the conclusions on specific tested components can also be extended to a more general set of components.
  • Calcium carbonate used in the control was identified as acceptable. Also tested and identified as acceptable were hectorite clay, sodium silicate treated hectorite clay, talc, portland cement, vermiculite, silicon carbide, Kaolin clay, peralite, mica, reprecipitated calcium carbonate, sand, gympsum, and aluminum trihydrate. Expanded poly(vinylidene chloride) beads (Expancel®) and aluminum flake were both identified as having unacceptable odor contribution.
  • the hectorite clay and sodium silicate treated hectorite clay appear to have superior odor properties (contributed less to odor intensity) compared to the control.
  • Talc, portland cement, vermiculite, and silicon carbide were not statistically significantly superior at a 95% confidence interval but may have been better than the control.
  • the expanded poly(vinylidene chloride) is an example of a polymeric degradation of an organic filler even at low levels (5% ofthe total formulation solids). This demonstrates that care must be taken when selecting organic fillers.
  • Aluminum flake was unacceptable even at low addition levels (5% ofthe total formulation solids). This demonstrates that even inert inorganics can be processed in such a way as to contribute odor. It is expected that appropriate treatment of the aluminum during the forming, rolling, and flaking process would result in a filler having acceptable odor contribution.
  • polyester (PET) fiber used in the control was identified as acceptable. Also tested and identified as acceptable were nylon 6, nylon 6,6, rayon and mineral wool. Unacceptable fibers included glass, polyaramid (Kevlar®), polypropylene, and a polyester/polyethylene blend.
  • nylon 6, nylon 6,6, rayon and mineral wool were all equivalent to the control.
  • the control polyester can represent an entire class of ester based condensation polymers that have high melting and deformation temperatures.
  • nylon 6 and nylon 6,6 represent the entire class of amide-hydroxyl condensation polymers as acceptable.
  • Unbleached, unrefined softwood used in the control was identified as acceptable. Also tested and identified as acceptable were bleached, unrefined softwood, bleached, unrefined hardwood, and bleached, refined softwood. In all cases the cellulose fiber used was acceptable and equivalent. The pulp sources tested represent pulp from more than just wood sources. It can be reasonably concluded that pulp from any source that has been appropriately processed and is not contaminated will have an acceptable odor contribution.
  • Methyl acrylate (used in the control latex), was identified as acceptable. Also tested and identified as acceptable were ethyl acrylate, butyl acrylate, butyl methacrylate, and vinylidene chloride. Marginally acceptable monomers included ethylhexyl acrylate. Unacceptable monomers included hexyl methacrylate and butadiene.
  • Vinylidene chloride showed acceptable odor properties. This can be thought of as representative ofthe general class of multi-halide substituted vinyl monomers. These would be considered appropriate for use from an odor contribution concern.
  • Butadiene was clearly unacceptable, and accordingly, its di-vinyl analogs are also considered unacceptable.
  • Methyl methacrylate (used in the control latex) was considered acceptable. Additionally, ethyl methacrylate, acrylonitrile and methyl ⁇ -chloroacrylate were tested and shown to be acceptable. Styrene was tested and consistently performed poorer than the methyl methacrylate control.
  • Methyl ⁇ -chloroacrylate represents the general class of mono-halide substitute vinyl monomers, of which vinyl chloride is a member. It is expected from this testing that this group and vinyl chloride in particular would be an acceptable set of monomers. Styrene and the substituted phenyl vinyl monomers it represents are clearly not prefened compared to methyl methacrylate but may still have some application.
  • Itaconic acid was used in the control polymer and was found to be acceptable. Also acceptable were fumaric acid, acrylic acid, methacrylic acid, acrylamide, sulfopropyl methacrylate, and hydroxyethyl acrylate. Marginally acceptable emulsion stabilizers included diethylaminoethyl methacrylate and sodium styrene sulfonate. 4-vinyl pyridine was unacceptable.
  • Itaconic, fumaric, acrylic, and methacrylic acids are representative of all ofthe mono and multi-carboxylic acid functional vinyl monomers, which should be considered acceptable.
  • Acrylamide represents all the simple amide functional monomers. They can all be considered acceptable monomers and equivalent to the weak vinyl acids for odor contribution.
  • the vinyl amide monomers may be considered equivalent in terms of odor contribution but inferior in terms of providing stability to the polymer.
  • Sulfopropyl methacrylate is representative of simple strong vinyl acids, including the sulfuric, sulfonic, and phosphonic types. It is equivalent to the weak vinyl acids in odor performance. It is also acceptable for latex stabilization and represents an alternative to weak vinyl acid stabilization.
  • Sodium styrene sulfonate represents more complex strong vinyl acids.
  • the resulting monomer has surfactant-like activity because of the size of the hydrophobic phenyl portion.
  • this monomer class is marginally acceptable as a monomer and reinforces that larger monomers tend to contribute greater odor.
  • Hydroxyethyl acrylate represents the general class of hydroxy modified emulsion stabilizers. With the requirement that the alkyl side chains remain below about 5 to 6 carbons in size, these appear to be an acceptable class of monomers and they aid significantly in the stabilization of the polymer during production.
  • Diethylaminoethyl methacrylate and 4-vinyl pyridine represent alkyl or cyclic amine functional monomers. The smaller alkyl side chains of the diethylaminoethyl methacrylate render it preferable to the 4-vinyl pyridine, but neither is acceptable, even at the very low levels used. The smaller amine functional monomers may be marginally acceptable for odor contribution. The larger amine functional vinyl monomers were clearly not acceptable. The difficulty with which successful polymerizations were made with these stabilizing monomers also contributes to their not being selected as prefened emulsion stabilizers.
  • Glycidyl methacrylate was the molecular weight modifier used for the control and was found to be acceptable for odor contribution. However, it clearly contributed more odor than a polymer made with no molecular weight modifier or with allyl methacrylate, ethylene glycol dimethacrylate, and N-methylol acrylamide. Glycidyl methacrylate may contribute marginally more odor than trimethylol propane triacrylate and is equivalent to the odor contributed by divinyl benzene. Tert-dodecyl mercaptan was clearly unacceptable.
  • Glycidyl methacrylate represents a class of multifunction molecular weight modifiers in which one functional group is a vinyl bond and the other is an epoxy group that will react with the carboxylic acid function of a vinyl acid. As such, it can only function as a molecular weight modifier if used in combination with a vinyl acid or other vinyl monomer that has a second function that is reactive with an epoxy group. While this class of modifiers is identified as acceptable and is prefened based on superior polymerization results, it clearly contributes more odor than several alternative molecular weight monomers.
  • Allyl methacrylate represents the class of simple divinyl monomers in which the two vinyl monomers are on dissimilar side-chains. It is superior to glycidyl methacrylate in terms of odor contribution and the general class is acceptable.
  • Ethylene glycol dimethacrylate represents the general class of multifunctional acrylate and methacrylate, primarily derivatized from glycol ethers. Recalling from the soft monomer study that longer substituted alkyl side chains contribute greater odor, this class of monomers is considered acceptable and superior to glycidyl methacrylate regarding odor contribution.
  • N-methylol acrylamide is a vinyl amide monomer with a methanol side chain on the amide nitrogen that is a reactive nucleophile. In the presence of vinyl acids, a crosslinking bond is formed. The monomer contributes less odor than glycidyl methacrylate and the general class is considered acceptable from an odor and processability assessment.
  • Trimethylol propane triacrylate represents a class of more complex multifunctional acrylate and methacrylate monomers. As anticipated from soft monomer work, the larger molecular weight modifier monomers are not as good as the less bulky alternatives. This is still an acceptable alternative for glycidyl methacrylate.
  • Divinyl benzene represents the general class of multi-vinyl functional styrene derivatives. As is the case with styrene, this monomer class is marginally acceptable and should only be used for lower thermal exposure conditions or in combination with other notably good monomers.
  • tert-Dodecyl mercaptan is a chain transfer agent and represents the general class of thio based chain transfer agents. This monomer class is not acceptable for odor.
  • a redox system would serve to reduce trace residuals of the monomers used in the polymerization by post- polymerization reaction.
  • the additives were examined by comparing the control emulsion polymer (methyl methacrylate/methyl acrylate/glycidyl methacrylate/fumaric acid) with the same control latex with the additives included.
  • the four samples were: 1) vitamin E (obtained through the Aldrich Chemical Company), 2) epoxidized soybean oil (commercially available from Union Carbide under the trade name FlexolTM, 3) an emulsion of a synthetic hindered phenol (commercially available from Akron Dispersions, Inc under the trade name Bostec 24), and 4) an emulsion of a synthetic hindered phenol with a synergist (commercially available from the Harwick Chemical Manufacturing Co ⁇ under the trade name Aquamix 494).
  • the redox system clearly improved the odor profile ofthe control polymer system. As such, it is considered acceptable and even desirable for the cunent polymer system.
  • the specific system used is only representative ofthe general class of redox systems. It is apparent that odor can be reduced through the use of a redox system. However, care needs to be taken when selecting the redox agents so that they do not contribute odor upon their own thermal decomposition.
  • antioxidants improved the odor profile of the polymer system tested and accordingly were considered acceptable, specifically, the vitamin E and the epoxidized soybean oil.
  • the hindered phenol and the hindered phenol/synergist emulsions were both marginally acceptable and appear to contribute an odor of their own to the system after thermal cycling. This demonstrates that the general class of antioxidants functions to reduce the rate of thermally activated oxidative degradation and thereby reduce the odor of the polymer after thermal exposure. However, care must be used in choosing an antioxidant that does not thermally degrade to produce odor.
  • reaction conditions during polymerization also play an important role in polymer produced from the reaction and thereby the potential for odor.
  • a system that is marginally acceptable may be made more acceptable and a system that is acceptable may be made superior.
  • reaction conditions There is an almost endless variety of reaction conditions that can be examined in an emulsion polymerization. To illustrate that manipulation of reaction conditions has an impact on the resulting polymer, three conditions were examined specifically: reaction temperature, mo ⁇ hological structuring, and initiator type.
  • the reaction temperature determines the relative rates of the primary propagation reaction during the polymerization as well as the relative rates of all the other competing reactions such as initiation, termination, and chain transfer. Accordingly, the polymerization temperature has an impact on the nature of the polymer produced. Reaction temperatures were varied from 75 °C to 105 °C. The resulting change in polymer structure could not be measured by the organoleptic testing. All the reaction temperatures were acceptable for odor contribution.
  • a polymer may be structured through composition drift or specific polymeric domains by changing the type or ratio of monomers used during the polymerization. This might be used to produce desirable physical properties in the final polymer or to reduce the cost of manufacturing the polymer by placing less expensive monomers in the core of the latex particle and covering them with a functional domain on the outside of the particle. By creating such a mo ⁇ hological structure, the odor contribution was roughly equivalent to a polymer made only from the least favorable monomers used.
  • initiator types are available for use to begin an emulsion polymerization.
  • a common commercial means of initiating would be to use a persulfate salt which initiates polymerization by a thermal decomposition reaction. This was the case with the control polymer.
  • An alternative would be to use an azo type initiator. In this specific case, the azo initiated polymer contributed more odor than the persulfate initiated polymer. The azo initiated polymer was only marginally acceptable for odor. The persulfate is prefened. This can be applied to the general class of initiators that a simpler salt will likely contribute less odor than a more complex organic molecule.
  • the thermoplastic epoxy contributed significant odor and was not acceptable.
  • the poly( vinyl acetate) emulsion can represent the entire class of vinyl acetate containing copolymers or acetate analogs.
  • the Vinac® 884 contributed significant odor as a resin and would not be considered acceptable.
  • the dispersed polymers were compared to the control methyl methacrylate/methyl acrylate/glycidyl methacrylate/fumaric acid latex.
  • a methyl cellulose ether (Methocel K4M®, commercially available from The Dow Chemical Company)
  • a protein corn Zein®, a prolamine derived from corn available from Acros Organics
  • a polysaccharide cationic guar gum available as BMB-9010 from Eka Chemicals.
  • the methyl cellulose ether had an odor contribution that was superior to the control and would be categorized as acceptable. This compound can reasonably represent the expected performance of general ethers and starches. These classes of compounds would be expected to give acceptable or superior odor contribution.
  • the Zein® contributed more odor than the control and was categorized as unacceptable. This chemical represents the general category of complex natural organic molecules of the protein class.
  • the cationic guar gum can act as both a binder and a cationic source. It contributed an odor intensity equivalent to the control and was found to be acceptable. Guar gum represents the general class of natural polysaccharide binders. It is believed that these binders will have acceptable odor contribution.
  • Flocculants Cationic polyacrylamide in water-in-oil emulsion (MX-10) and colloidal silica (BMA-780) used in the control formulation as the two flocculants were identified as acceptable. Additional acceptable flocculants included quarternary acrylate salt/acrylamide copolymers, sodium acrylate/acrylamide copolymers, acrylamide copolymer in hydrocarbon/water emulsion, and bentonite clay. Polyethyleneimine had unacceptable odor contribution. While the majority of flocculants had an acceptable odor profile, it is clear from the polyethyleneimine results that care must be taken regarding selection. The results reinforce the results ofthe emulsion stabilizer study in which acrylic and amide functions were generally acceptable for odor contribution but more complex nitrogen containing compounds were not.
  • Alum and a cationic amine copolymer-epichlorohydrin adduct were used in the control formulation and identified as acceptable as cationic sources.
  • Cationic guar gum as mentioned above, also had an acceptable odor contribution.
  • the control formulation did not have a colorant added and was identified as having acceptable odor intensity. Carbon black was added at the 2% level and an improvement was seen in the odor intensity. Pthalo green pigment, red dye, and carta yellow dye were added at the 2% level and judged acceptable for odor contribution. While not statistically superior to the control formulation with no colorant at the 95% confidence level, these three colorants may contribute less odor intensity than the control. Equivalent to the control and identified as acceptable were iron oxide red, pthalo blue pigment, titanium dioxide, and red 40 aluminum lake.
  • the carbon black formulation was clearly superior to the colorant free control and may show the ability of some species to act as a fugitive chemical sink even at elevated temperatures. As a general group, colorants do not contribute additional odor to the formulation.
  • a preferred formulation might include the following components:
  • Filler clay, calcium carbonate, talc
  • Fiber cellulose (unbleached, unrefined softwood), polyethylene terephthalate, nylon 6, nylon 6,6, rayon, mineral wool
  • Soft monomer methyl acrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, vinylidene chloride.
  • Hard monomer methyl methacrylate, ethyl methacrylate, acrylonitrile, vinyl chloride.
  • Polymerizable emulsion stabilizer itaconic acid, fumaric acid, acrylic acid, methacrylic acid, acrylamide, sulfopropyl methacrylate, 2-hydroxyethyl acrylate
  • Molecular weight modifier glycidyl methacrylate, allyl methacrylate, ethylene glycol dimethacrylate, N-methylol acrylamide, trimethylol propone triacrylate.
  • Reduction-oxidation post-reaction additives t-butyl hydroperoxide and sodium meta- bisulfite
  • Antioxidant additives vitamin E, epoxidized soybean oil
  • Flocculants cationic polyacrylamide in water-in-oil emulsion, quaternary acrylate salt/acrylamide copolymers, sodium acrylate/acrylamide copolymer, acrylamide copolymer in hydrocarbon/water emulsion, and bentonite clay
  • Cationic sources alum, cationic amine copolymer-epichlorohydrin adduct, cationic guar gum
  • the most prefened formulation would include clay, cellulose fiber, polyethylene terephthalate fiber, a latex binder with the composition methyl acrylate, methyl methacrylate, itaconic acid, and glycidyl methacrylate (the soft and hard monomers would be proportioned such that the glass transition temperature is between 0 and 125°C, and more preferably between 60 and 90°C), cationic polyacrylamide in water-in-oil emulsion and bentonite clay flocculants, cationic amine copolymer-epichlorohydrin adduct cationic source, and carbon black.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Food Science & Technology (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Paper (AREA)
  • Package Specialized In Special Use (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • General Preparation And Processing Of Foods (AREA)

Abstract

L'invention concerne un article thermostable qui peut s'utiliser, dans un mode de réalisation, comme récipient de cuisson conçu pour recevoir des aliments dans un four à des températures pouvant atteindre 600 °F sans produire d'odeurs désagréables. L'article est constitué d'un matériau composite chargé comportant une charge, une matière fibreuse, et un liant sélectionné parmi des latex synthétiques et des polymères synthétiques dispersés. L'article peut être formé selon un processus semblable à celui de la fabrication du papier ou du moulage de pâte au cours duquel le matériau composite chargé est colloïdalement déstabilisé et formé en un article modelé.
PCT/US2000/026653 1999-09-30 2000-09-28 Article thermostable, composition de latex, et procede de fabrication WO2001023471A1 (fr)

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AU76208/00A AU7620800A (en) 1999-09-30 2000-09-28 Heat stable article, latex composition, and method of making

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US15685499P 1999-09-30 1999-09-30
US60/156,854 1999-09-30

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PCT/US2000/026635 WO2001023276A1 (fr) 1999-09-30 2000-09-28 Procede d'emballage et de cuisson d'aliments dans un recipient allant au four

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010069329A1 (fr) * 2008-12-16 2010-06-24 Carlsberg A/S Matériau polymère à base de cellulose
WO2011087438A1 (fr) * 2010-01-12 2011-07-21 Innventia Ab Matériau moulable
US9029470B2 (en) 2009-02-24 2015-05-12 Akzo Nobel Coatings International B.V. Latex emulsions and coating compositions formed from latex emulsions
US9133292B2 (en) 2009-03-05 2015-09-15 Akzo Nobel Coatings International B.V. Hydroxyl functional oil polyol acrylic graft copolymers
US9260625B2 (en) 2011-12-21 2016-02-16 Akzo Nobel Coatings International B.V. Water-based coating compositions
US9273226B2 (en) 2011-12-21 2016-03-01 Akzo Nobel Coatings International B.V. Solvent-based coating compositions
US9394456B2 (en) 2009-02-24 2016-07-19 Akzo Nobel Coatings International B.V. Latex emulsions and coating compositions formed from latex emulsions
US9458345B2 (en) 2010-12-28 2016-10-04 Akzo Nobel Coatings International B.V. Coating compositions comprising latex emulsions and hydroxyl functional oil polyol graft copolymers
US10800941B2 (en) 2014-12-24 2020-10-13 Valspar Sourcing, Inc. Coating compositions for packaging articles such as food and beverage containers
US10968288B2 (en) 2014-12-24 2021-04-06 Swimc Llc Styrene-free coating compositions for packaging articles such as food and beverage containers
US11059989B2 (en) 2017-06-30 2021-07-13 Valspar Sourcing, Inc. Crosslinked coating compositions for packaging articles such as food and beverage containers
US11981822B2 (en) 2014-12-24 2024-05-14 Swimc Llc Crosslinked coating compositions for packaging articles such as food and beverage containers

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2557267C (fr) 2004-03-01 2013-04-23 Kraft Foods Holdings, Inc. Ensemble de preparation d'aliment a usages multiples
DE202004018759U1 (de) * 2004-12-04 2005-03-03 Kaya, Nihat Behältnis zum Lagern sowie zum Kochen oder Backen von Gerichten
WO2015048655A1 (fr) * 2013-09-27 2015-04-02 Sabert Corporation Conteneur comprenant une base en pulpe moulée et un couvercle plastique ventilé pour conserver le croustillant d'aliments sensibles à l'humidité
DE102015101404B4 (de) * 2015-01-30 2020-07-16 Emilio Giusti Abdeckung für Speisen
JP2019182520A (ja) * 2018-04-16 2019-10-24 凸版印刷株式会社 電子レンジ加熱用パウチ

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US4477509A (en) * 1982-08-19 1984-10-16 Mott Joseph J Disposable lid for pots, pans and like receptacles
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US5565228A (en) * 1995-05-02 1996-10-15 Gics & Vermee, L.P. Ovenable food product tray and an ovenable food product package

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8796362B2 (en) 2008-12-16 2014-08-05 Carlsberg A/S Cellulose based polymer material
CN102317365B (zh) * 2008-12-16 2014-08-13 嘉士伯有限公司 基于纤维素的聚合物材料
EA021761B1 (ru) * 2008-12-16 2015-08-31 Карлсберг А/С Полимерный материал на основе целлюлозы
EA021761B9 (ru) * 2008-12-16 2015-12-30 Карлсберг А/С Полимерный материал на основе целлюлозы
WO2010069329A1 (fr) * 2008-12-16 2010-06-24 Carlsberg A/S Matériau polymère à base de cellulose
US9428635B2 (en) 2008-12-16 2016-08-30 Carlsberg A/S Coating of hydroxylated surfaces by gas phase grafting
US9394456B2 (en) 2009-02-24 2016-07-19 Akzo Nobel Coatings International B.V. Latex emulsions and coating compositions formed from latex emulsions
US9029470B2 (en) 2009-02-24 2015-05-12 Akzo Nobel Coatings International B.V. Latex emulsions and coating compositions formed from latex emulsions
US9133292B2 (en) 2009-03-05 2015-09-15 Akzo Nobel Coatings International B.V. Hydroxyl functional oil polyol acrylic graft copolymers
WO2011087438A1 (fr) * 2010-01-12 2011-07-21 Innventia Ab Matériau moulable
US9458345B2 (en) 2010-12-28 2016-10-04 Akzo Nobel Coatings International B.V. Coating compositions comprising latex emulsions and hydroxyl functional oil polyol graft copolymers
US9273226B2 (en) 2011-12-21 2016-03-01 Akzo Nobel Coatings International B.V. Solvent-based coating compositions
US9260625B2 (en) 2011-12-21 2016-02-16 Akzo Nobel Coatings International B.V. Water-based coating compositions
US10800941B2 (en) 2014-12-24 2020-10-13 Valspar Sourcing, Inc. Coating compositions for packaging articles such as food and beverage containers
US10968288B2 (en) 2014-12-24 2021-04-06 Swimc Llc Styrene-free coating compositions for packaging articles such as food and beverage containers
US11332636B2 (en) 2014-12-24 2022-05-17 Swimc Llc Coating compositions for packaging articles such as food and beverage containers
US11725067B2 (en) 2014-12-24 2023-08-15 Swimc Llc Styrene-free coating compositions for packaging articles such as food and beverage containers
US11981822B2 (en) 2014-12-24 2024-05-14 Swimc Llc Crosslinked coating compositions for packaging articles such as food and beverage containers
US11059989B2 (en) 2017-06-30 2021-07-13 Valspar Sourcing, Inc. Crosslinked coating compositions for packaging articles such as food and beverage containers

Also Published As

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AR025935A1 (es) 2002-12-18
WO2001023276A1 (fr) 2001-04-05
AU7620800A (en) 2001-04-30
CO5160368A1 (es) 2002-05-30
AU7620700A (en) 2001-04-30

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