ZIEGELMAN DUSTIN (US)
ZHANG YIYAN (US)
GONZALEZ RIC (US)
WANG MIN (US)
US20200024806A1 | 2020-01-23 | |||
US5800647A | 1998-09-01 | |||
US20180339826A1 | 2018-11-29 | |||
US20180016750A1 | 2018-01-18 | |||
US5709913A | 1998-01-20 |
CLAIMS 1. A method of manufacturing a microwave bowl, comprising the steps of: providing a wire mesh mold approximating the shape of the meat tray; preparing an aqueous fiber based slurry comprising at least one of old corrugated containers (OCC) and double-lined kraft (DLK) paper; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the bowl; transferring the bowl from the press to a coating station; and applying a non-acrylate moisture barrier layer to a surface of the bowl at the coating station. 2. The method of claim 1, wherein the embedded moisture barrier comprises 2% – 5% by weight alkyl ketene dimer (AKD). 3. The method of claim 1, further comprising: adding a dry strength additive to the slurry. 4. The method of claim 3, wherein the dry strength additive comprises .5% - 4.5% by weight starch. 5. The method of claim 1, wherein the coating station comprises: a spray system; and a conveyor configured to move the bowl along a direction of travel into engagement with the spray system. 6. The method of claim 5, wherein the spray system comprises a first nozzle configured to discharge a first predetermined spray pattern onto a bottom of the bowl. 7. The method of claim 6, wherein the first predetermined spray pattern comprises a substantially vertical curtain terminating in a line at the bowl. 8. The method of claim 6, wherein the spray system further comprises a second nozzle configured to discharge a second predetermined spray pattern onto a sidewall of the bowl. 9. The method of claim 1, wherein the moisture barrier layer comprises non-acrylate based particulate solids in an aqueous solution. 10. The method of claim 1, wherein the moisture barrier layer comprises an approximately 1:3 solution of particulates and water. 11. A method of manufacturing a microwave bowl of the type characterized by a substantially flat, circular, bottom region bounded by a circumferential sidewall, comprising the steps of: providing a wire mesh mold approximating the shape of the bowl; preparing an aqueous fiber based slurry comprising at least one of hardwood virgin fiber and softwood virgin fiber; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the bowl; transferring the bowl from the press to a coating station; and applying a topical barrier layer to the inside surfaces of the bowl at the coating station. 12. The method of claim 11, wherein the embedded moisture barrier comprises 2% – 5% alkyl ketene dimer (AKD). 13. The method of claim 11, further comprising: adding a dry strength additive to the slurry, wherein the dry strength additive comprises .5% - 4.5% starch. 14. The method of claim 11, wherein the topical barrier layer comprises about 6.5% - 8.5% solids in a water solution. 15. The method of claim 14, wherein the topical barrier comprises polyvinyl alcohol, sugar alcohol, citric acid, and cellulose nanofibrils (CNF). 16. The method of claim 14, wherein the topical barrier comprises 30% - 40% polyvinyl alcohol, about 30% - 50% sugar alcohol, 9% - 18% citric acid, and 4.5% - 6.5% CNF. 17. The method of claim 14, wherein the topical barrier comprises about 36% polyvinyl alcohol, about 45% sugar alcohol, about 13.5% citric acid, and about 5.5% CNF. 18. The method of claim 11, wherein the topical barrier layer comprises about 6% - 8% solids in a water solution. 19. The method of claim 18, wherein the topical barrier comprises 30% - 40% polyvinyl alcohol, about 30% - 50% sugar alcohol, 9% - 18% citric acid, and 3% - 12% CNF. 20. The method of claim 18, wherein the topical barrier comprises about 38% polyvinyl alcohol, about 38% sugar alcohol, about 14% citric acid, and about 10% CNF. |
[0066] More generally, the DWP spray coating may be described as an aqueous formulation containing in the range of 15 – 40% by weight total solids, and preferably in the range of 25 – 30%, and most preferably about 27.5%. One ingredient in this formulation may comprise acrylic polymers which, upon curing, crosslink and polymerize to facilitate forming desired moisture, oil, and/or oxygen barrier layers. This formulation also contains rice bran wax to provide non-stick properties and non-glossy surface finishing of the coated surface. The wax is emulsified with pea protein for stable aqueous dispersal. This formulation also contains pectin as a viscosity modifier for optimal adhesion to hydrophobic fibrous surface during spray coating. pH of formulation is around 9.0 with added ammonia to maintain solubility of the acrylic polymers. [0067] Exemplary methods for preparing a solution to applied as a topical coating will now be described in the context of a seventy-five (75) gallon batch using the following definitions: RBW: Rice Bran Wax PP: Pea Protein Pec: Pectin G: Gallons L: Liters kg: Kilograms [0068] Heat 35.6 gallons of water to at least 185 °F, and mix in 5.1 kg RBW at high speed for approximately 12 minutes until the wax pellets are fully melted and the temperature of the solution returns to 185 °F. Add .85 kg PP to the mixture over approximately one minute. Mix the PP for an additional ten minutes or longer until no clumps are visible. Add 1.14 kg Pec over .5 minutes and allow the contents to mix for an additional 15 minutes or longer until there no clumps are visible. Continue mixing at low speed and bring the batch temperature to approximately 120 °F. While mixing add 37.5 gallons Rhobarr 110 to the batch and continue to mix for ten minutes. Slowly pour 2.15 L of 4% ammonia to the batch and continue mixing for ten additional minutes. [0069] Referring now to FIG. 1, an exemplary vacuum forming system and process 100 using a fiber-based slurry includes a first stage 101 in which mold (not shown for clarity) in the form of a mirror image of the product to be manufactured is envelop in a thin wire mesh form 102 to match the contour of the mold. A supply 104 of a fiber-based slurry 104 is input at a pressure (P1) 106 (typically ambient pressure). By maintaining a lower pressure (P2) 108 inside the mold, the slurry is drawn through the mesh form, trapping fiber particles in the shape of the mold, while evacuating excess slurry 110 for recirculation back into the system. [0070] With continued reference to FIG. 1, a second stage 103 involves accumulating a fiber layer 130 around the wire mesh in the shape of the mold. When the layer 130 reaches a desired thickness, the mold enters a third stage 105 for either wet or dry curing. In a wet curing process, the formed part is transferred to a heated press (not shown) and the layer 130 is compressed and dried to a desired thickness, thereby yielding a smooth external surface finish for the finished part. In a dry curing process, heated air is passed directly over the layer 130 to remove moisture therefrom, resulting in a more textured finish much like a conventional egg carton. [0071] In accordance with various embodiments the vacuum mold process is operated as a closed loop system, in that the unused slurry is re-circulated back into the bath where the product is formed. As such, some of the chemical additives (discussed in more detail below) are absorbed into the individual fibers, and some of the additive remains in the water-based solution. During vacuum formation, only the fibers (which have absorbed some of the additives) are trapped into the form, while the remaining additives are re-circulated back into the tank. Consequently, only the additives captured in the formed part must be replenished, as the remaining additives are re-circulated with the slurry in solution. As described below, the system maintains a steady state chemistry within the vacuum tank at predetermined volumetric ratios of the constituent components comprising the slurry. [0072] Referring now to FIG. 2, is a closed loop slurry system 200 for controlling the chemical composition of the slurry. In the illustrated embodiment a tank 202 is filled with a fiber-based slurry 204 having a particular desired chemistry, whereupon a vacuum mold 206 is immersed into the slurry bath to form a molded part. After the molded part is formed to a desired thickness, the mold 206 is removed for subsequent processing 208 (e.g., forming, heating, drying, top coating, and the like). [0073] In a typical wet press process, the Hot Press Temperature Range is around 150-250 degree C, with a Hot Press Pressure Range around 140-170kg/cm 2 . The final product density should be around 0.5-1.5 g/cm 3 , and most likely around 0.9-1.1 g/cm 3 . Final product thickness is about 0.3-1.5mm, and preferably about 0.5-0.8mm. [0074] With continued reference to FIG. 2, a fiber-based slurry comprising pulp and water is input into the tank 202 at a slurry input 210. In various embodiments, a grinder may be used to grind the pulp fiber to create additional bonding sites. One or more additional components or chemical additives may be supplied at respective inputs 212 – 214. The slurry may be re-circulated using a closed loop conduit 218, adding additional pulp and/or water as needed. To maintain a steady state balance of the desired chemical additives, a sampling module 216 is configured to measure or otherwise monitor the constituent components of the slurry, and dynamically or periodically adjust the respective additive levels by controlling respective inputs 212 – 214. Typically, the slurry concentration is around 0.1-1%, most ideally around 0.3-0.5% and preferably about 0.4 - 0.5%. In one embodiment, the various chemical constituents are maintained at a predetermined desired percent by volume; alternatively, the chemistry may be maintained based on percent by weight or any other desired control modality. [0075] The pulp fiber used in 202 can also be mechanically grinded to improve fiber-to- fiber bonding and improve bonding of chemicals to the fiber. In this way the slurry undergoes a refining process which changes the freeness, or drainage rate, of fiber materials. Refining physically modifies fibers to fibrillate and make them more flexible to achieve better bonding. Also, the refining process can increase tensile and burst strength of the final product. Freeness, in various embodiments, is related to the surface conditions and swelling of the fibers. Freeness (csf) is suitably within the range of 200-700, and preferably about 350 - 550 for many of the processes and products described herein. [0076] Various chemical formulations (sometimes referred to herein as “chemistries”), spray coating and immersion systems, and nozzle configurations and product configurations for various fiber-based packages and containers, as well as various methods for applying topical coatings, will now be further described in conjunction with FIGS.3–8. [0077] FIG. 3 is a perspective view of a meat tray 300 illustrating the underside 302 of the bottom surface and the outside surfaces of side walls 304. [0078] FIG. 4 is a side elevation view of the meat tray 402 of FIG. 3. [0079] FIG. 5 is a top plan view of the meat tray of FIGS. 3 and 4 illustrating the top surface 502 of the bottom region of the tray, and respective side walls 504 and 506. [0080] FIG. 6 is an end view of the meat tray 602 of FIG. 5. [0081] FIG. 7 is a schematic perspective of a spray coating system 700 useful for spray coating meat trays in accordance with various embodiments. [0082] More particularly, system 700 includes a conveyor 708 having a pocket 710 for holding a tray as it is conveyed along a direction indicated by arrow 730. The tray includes a bottom panel 704 having structural features (e.g. ribs) 706 and is circumscribed by a side wall 702. [0083] With continued reference to FIG. 7, the illustrated spray system comprises respective first and second spray nozzles 712 and 718. Nozzle 712 is configured to discharge a substantially planar spray pattern 715 bounded by side edges 714 and terminating in a line 716 substantially orthogonal to direction 730. Nozzle 718 is configured to discharge a substantially planar spray pattern 721 bounded by side edges 720 and terminating in a line 716 substantially orthogonal to direction 722. As the tray passes underneath the spray nozzles, spray lines 716 and 722 apply the coating to all or selected portions of bottom surface 704 and/or the inside surfaces of sidewall 702. [0084] FIG. 8 is a schematic perspective of a spray coating system 800 including a full cone nozzle 810 configured to discharge a full cone spray pattern, and a hollow cone nozzle 814 configured to discharge an annular (or “doughnut”) shaped spray pattern. In particular, system 800 is configured to apply a full cone spray pattern 812 to an inside bottom surface 802 of the workpiece (bowl). System 800 is further configured to apply a hollow cone spray pattern 816 to the inside surface of the workpiece side walls 804. [0085] With continued reference to FIG. 8, conveyor 806 is configured to carry trays along a direction defined by arrow 830 (to the right in FIG. 8). In one embodiment, conveyor 806 may be configured to sequentially index in the direction of arrow 830 to thereby position successive trays under stationary nozzles 810, 814 suspended from stationary platen 820. In this position, the bowl on the left may have its bottom spray coated while the bowl on the right has its sidewalls spray coated. After indexing to the next position, the bowl previously underneath nozzle 810 is then disposed under nozzle 814, and so on. [0086] In an alternate embodiment, total workpiece throughput may be increased by operating conveyor 806 in a continuous fashion (as opposed to sequentially indexing). In order to maintain positional registration between the nozzle system and the underlying workpieces during application of the spray coating, platen 820 may be configured to travel to the right along with conveyor 830 to temporarily suspend relative motion between the nozzles, and thereafter shift leftwardly to align the nozzles with the next series of workpieces to be coated. [0087] While FIG. 8 illustrates two workpieces and one of each of a full cone and hollow cone nozzle, those skilled in the art will appreciate that the system may be scaled to accommodate any number of nozzles and workpieces for each reciprocating operation of platen 820. [0088] As briefly mentioned above, the various slurries used to vacuum mold containers according to the present invention comprises a fiber base mixture of pulp and water, with added chemical components to impart desired performance characteristics tuned to each particular product application. The base fiber may include any one or combination of at least the following materials: softwood (SW), bagasse, bamboo, old corrugated containers (OCC), and newsprint (NP). Alternatively, the base fiber may be selected in accordance with the following resources, the entire contents of which are hereby incorporated by this reference: “Lignocellulosic Fibers and Wood Handbook: Renewable Materials for Today's Environment,” edited by Mohamed Naceur Belgacem and Antonio Pizzi (Copyright 2016 by Scrivener Publishing, LLC) and available at “Efficient Use of Flourescent Whitening Agents and Shading Colorants in the Production of White Paper and Board” by Liisa Ohlsson and Robert Federe, Published October 8, 2002 in the African Pulp and Paper Week and available at Efficient_use_of_fluorescent_w/efficient_use_of_fluorescent_ w.html; Cellulosic Pulps, Fibres and Materials: Cellucon ’98 Proceedings, edited by J F Kennedy, G O Phillips, P A Williams, copyright 200 by Woodhead Publishing Ltd. and available at books. and U.S. Patent No. 5,169,497 A entitled “Application of Enzymes and Flocculants for Enhancing the Freeness of Paper Making Pulp” issued December 8, 1992. [0089] For vacuum molded produce containers manufactured using either a wet or dry press, a fiber base of OCC or OCC/DLK and NP may be used, where the OCC/DLK component is between 50% - 100%, and preferably about 70% OCC/DLK and 30% NP or VNP, with an added moisture/water repellant in the range of 1% – 10% by weight, and preferably about 1.5% - 4%, and most preferably about 4%. In a preferred embodiment, the moisture/water barrier may comprise alkyl ketene dimer (AKD) (for example, Hercon 79, Hercon 80) and/or long chain diketenes, available from FOBCHEM at fobchem.com/html_products/Alkyl-Ketene-Dimer%EF%BC%88AKD- WAX%EF%BC%89.html#.V0zozvkrKUk; and Yanzhou Tiancheng Chemical Co., Ltd. at yztianchengchem.com/en/index.php?m=content&c=index&a =show&catid=38&id=124&gclid =CPbn65aUg80CFRCOaQod0JUGRg. [0090] In order to yield specific colors for molded pulp products, cationic dye or fiber reactive dye may be added to the pulp. Fiber reactive dyes, such as Procion MX, bond with the fiber at a molecular level, becoming chemically part of the fabric. Also, adding salt, soda ash and/or increase pulp temperature will help the absorbed dye to be furtherly locked in the fabric to prevent color bleeding and enhance the color depth. [0091] To enhance structural rigidity, a starch component may be added to the slurry, for example, liquid starches available commercially as Topcat® L98 cationic additive (or Hercobond 6950 available from Solenis LLC), Hercobond, and Topcat® L95 cationic additive (available from Penford Products Co. of Cedar Rapids, Iowa). Alternatively, the liquid starch can also be combined with low charge liquid cationic starches such as those available as Penbond® cationic additive and PAF 9137 BR cationic additive (also available from Penford Products Co., Cedar Rapids, Iowa). [0092] For dry press processes, Topcat L95 or Hercobond 6950 may be added as a percent by weight in the range of 0.5% - 10%, and preferably about 1% - 7%, and particularly for products which need maintain strength in a high moisture environment most preferably about 6.5%; otherwise, most preferably about 1.5-2.0%. For wet press processes, dry strength additives such as Topcat L95 or Hercobond 6950 which are made from modified polyamines that form both hydrogen and ionic bonds with fibers and fines. Dry strength additives help to increase dry strength, as well as drainage and retention, and are also effective in fixing anions, hydrophobes and sizing agents into fiber products. Those additives may be added as a percent by weight in the range of 0.5% - 10%, and preferably about 1% - 6%, and most preferably about 3.5%. In addition, both wet and dry processes may benefit from the addition of wet strength additives, for example solutions formulated with polyamide-epichlorohydrin (PAE) resin such as Kymene 920A or 1500 or similar component available from Ashland Specialty Chemical Products at ashland.com/products. In a preferred embodiment, Kymene 920A or 1500 may be added in a percent by volume range of 0.5% - 10%, and preferably about 1% - 4%, and most preferably about 2% or equal amount with dosing of dry strength additives. Kymene 920A or 1500 is of the class of polycationic materials containing an average of two or more amino and/or quaternary ammonium salt groups per molecule. Such amino groups tend to protonate in acidic solutions to produce cationic species. Other examples of polycationic materials include polymers derived from the modification with epichlorohydrin of amino containing polyamides such as those prepared from the condensation adipic acid and dimethylene triamine, available commercially as Hercosett 57 from Hercules and Catalyst 3774 from Ciba-Geigy. [0093] The present inventor has determined that molded fiber containers can be rendered suitable as single use food containers suitable for use in microwave, convection, and conventional ovens by embedding barrier chemistries into the slurry, adding a topical coating to the finished vacuum formed container, or both. In particular, the slurry and/or topical coating chemistry should advantageously accommodate one or more of the following three performance metrics: i) moisture barrier; ii) oil barrier; and iii) water vapor (condensation) barrier to avoid condensate due to placing the hot container on a surface having a lower temperature than the container. [0094] In this context, the extent to which water vapor permeates the container is related to the porosity of the container, which the present invention seeks to reduce. That is, even if the container is effectively impermeable to oil and water, it may nonetheless compromise the user experience if water vapor permeates the container, particularly if the water vapor condenses on a cold surface, leaving behind a moisture ring. The present inventor has further determined that the condensate problem is uniquely pronounced in fiber-based applications because water vapor typically does not permeate a plastic barrier. [0095] Accordingly, for microwavable containers the present invention contemplates a fiber or pulp-based slurry including a water barrier, oil barrier, and water vapor barrier, and an optional retention aid. In an embodiment, a fiber base of softwood (SW)/bagasse at a ratio in the range of about 10% - 90%, and preferably about 7:3 may be used. As a moisture barrier, AKD may be used in the range of about .5% - 10%, and preferably about 1.5% - 4%, and most preferably about 3.5%. As an oil barrier, the grease and oil repellent additives are usually water based emulsions of fluorine containing compositions of fluorocarbon resin or other fluorine-containing polymers such as UNIDYNE TG 8111 or UNIDYNE TG-8731 available from Daikin or World of Chemicals at worldofchemicals.com/chemicals/chemical- The oil barrier component of the slurry (or topical coat) may comprise, as a percentage by weight, in the range of .5% - 10%, and preferably about 1% - 4%, and most preferably about 2.5%. As a retention aid, an organic compound such as Nalco 7527 available from the Nalco Company of Naperville, Ill. May be employed in the range of 0.1% - 1% by volume, and preferably about 0.3%. Finally, to strengthen the finished product, a dry strength additive such as an inorganic salt (e.g., Hercobond 6950 available at solenis.com/en/industries/tissue-towel/innovations/hercobond -dry-strength-additives/; see also sfm.state.or.us/CR2K_SubDB/MSDS/HERCOBOND_6950.PDF) may be employed in the range of 0.5% - 10% by weight, and preferably about 1.5% - 5%, and most preferably about 4%. [0096] As mentioned, vapor barrier performance is directly impacted by porosity of the fiber tray. Reducing the porosity of the fiber tray and, hence, improving vapor barrier performance can be achieved using at least two approaches. One is by improving freeness of the tray material by grinding the fibers. The second way is by topical spray coating using, for example, Daikin S2066, which is a water based long chain Fluorine-containing polymer. Spray coating may be implemented using in the range of about 0.1% - 3% by weight, and preferably about 0.2% - 1.5 %, and most preferably about 1%. [0097] Presently known meat trays, such as those used for the display of poultry, beef, pork, and seafood in grocery stores, are typically made of plastic based materials such as polystyrene and Styrofoam, primarily because of their superior moisture barrier properties. The present inventor has determined that variations of the foregoing chemistries used for microwavable containers may be adapted for use in meat trays, particularly with respect to the moisture barrier (oil and porosity barriers are typically not as important in a meat tray as they are in a microwave container). [0098] Accordingly, for meat containers the present invention contemplates a fiber or pulp-based slurry including a water barrier and an optional oil barrier. In an embodiment, a fiber base of softwood (SW)/bagasse and/or bamboo/bagasse at a ratio in the range of about 10% - 90%, and preferably about 7:3 may be used. As a moisture/water barrier, AKD may be used in the range of about 0.5% - 10%, and preferably about 1% - 4%, and most preferably about 4%. As an oil barrier, a water based emulsion may be employed such as UNIDYNE TG 8111 or UNIDYNE TG-8731. The oil barrier component of the slurry (or topical coat) may comprise, as a percentage by weight, in the range of 0.5% - 10%, and preferably about 1% - 4%, and most preferably about 1.5%. Finally, to strengthen the finished product, a dry strength additive such as Hercobond 6950 may be employed in the range of 0.5% - 10% by weight, and preferably about 1.5% - 4%, and most preferably about 4%. [0099] As discussed above in connection with the produce containers, the slurry chemistry and/or spray coating chemistry may be combined with structural features to provide prolonged rigidity over time by preventing moisture/water from penetrating into the tray. [0100] A method of manufacturing a meat tray is thus provided. The method includes: providing a wire mesh mold approximating the shape of the meat tray; preparing an aqueous fiber based slurry comprising at least one of old corrugated containers (OCC) and double- lined kraft (DLK) paper; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the meat tray; transferring the meat tray from the press to a coating station; and applying a supplemental moisture barrier layer to a surface of the meat tray at the coating station. [0101] In an embodiment, the embedded moisture barrier comprises 2% – 5% alkyl ketene dimer (AKD). [0102] In an embodiment, the method further includes adding a dry strength additive to the slurry. [0103] In an embodiment, the dry strength additive comprises 0.5% - 4.5% starch. [0104] In an embodiment, the coating station comprises: a spray system; and a conveyor configured to move the meat tray along a direction of travel into engagement with the spray system. [0105] In an embodiment, the spray system comprises a first nozzle configured to discharge a first predetermined spray pattern onto the meat tray. [0106] In an embodiment, the first predetermined spray pattern comprises a substantially vertical curtain terminating in a line at the meat tray, the line having a predetermined thickness and oriented substantially orthogonal to the direction of travel. [0107] In an embodiment, the spray system further includes a second nozzle configured to discharge a second predetermined spray pattern onto the meat tray, wherein the first spray pattern is angled toward the direction of travel and the second spray pattern is angled away from the direction of travel. [0108] In an embodiment, the supplemental moisture barrier layer comprises an acrylic copolymer latex in an aqueous solution. [0109] In an embodiment, the supplemental moisture barrier layer comprises an approximately 1:3 solution of acrylic and water. [0110] A method is also provided for manufacturing a microwave bowl of the type characterized by a substantially flat, circular, bottom region bounded by a circumferential sidewall. The method includes: providing a wire mesh mold approximating the shape of the bowl; preparing an aqueous fiber based slurry comprising at least one of hardwood virgin fiber and softwood virgin fiber; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the bowl; transferring the bowl from the press to a coating station; and applying a topical oil barrier layer to at least a portion of the bowl at the coating station. [0111] In an embodiment, the embedded moisture barrier comprises 2% – 5% alkyl ketene dimer (AKD). [0112] In an embodiment, the method further includes adding a dry strength additive to the slurry, wherein the dry strength additive comprises 0.5% - 4.5% starch. [0113] In an embodiment, the topical oil barrier layer comprises about 27.5% solids in a water solution. [0114] In an embodiment, the solids comprise acrylate, rice bran wax, pectin, and pea protein. [0115] In an embodiment, the coating station includes: a spray system; and a conveyor configured to move the bowl along a direction of travel underneath the spray system. [0116] In an embodiment, the spray system includes: a first nozzle configured to discharge a full cone spray pattern onto the bottom region of the bowl; and a second nozzle configured to discharge a hollow cone spray pattern onto the inside surface of the circumferential sidewall. [0117] In an embodiment, the method further includes the step of moving the spray system along the direction of travel such that: i) the first nozzle is disposed above and remains stationary with respect to the bowl for a first predetermined period of time; and ii) the second nozzle is disposed above and remains stationary with respect to the bowl for a second predetermined period of time. [0118] In an embodiment, the first period of time is one of: i) greater than; ii) equal to; and iii) less than the second period of time. [0119] A method is provided for manufacturing a fiber based microwave bowl of the type including a substantially circular bottom portion bounded by an inclined circumferential side wall. The method may include the steps of: providing a wire mesh mold approximating the shape of the bowl; preparing an aqueous fiber based slurry comprising up to 100% virgin fiber; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the bowl; transferring the bowl from the press to a coating station; and applying an acrylic based oil barrier layer to a surface of the bowl at the coating station. [0120] In an embodiment, the embedded moisture barrier comprises 2% – 5% alkyl ketene dimer (AKD). [0121] In an embodiment, the oil barrier layer comprises a calcium carbonate component to facilitate bonding to a bowl surface. [0122] In an embodiment, the oil barrier layer comprises a pea emulsion. [0123] In an embodiment, the oil barrier layer comprises an alginate. [0124] In an embodiment, the oil barrier layer comprises an aqueous solution including about 25% acrylate and a first supplemental component configured to reduce tackiness. [0125] In an embodiment, the first supplemental component comprises about 1.8 % rice bran wax. [0126] In an embodiment, the first supplemental component comprises about 0.4% pectin. [0127] In an embodiment, the oil barrier layer comprises a second supplemental component configured to facilitate emulsion of the first supplemental component. [0128] In an embodiment, the second supplemental component comprises about 0.3% pea protein. [0129] In an embodiment, the oil barrier layer comprises a third supplemental component configured to adjust the PH level of the oil barrier coating to thereby facilitate acrylate curing. [0130] In an embodiment, the third supplemental component comprises about 0.2% liquid ammonium. [0131] In an embodiment, the coating station comprises: a spray system; and a conveyor configured to move the bowl along a direction of travel into engagement with the spray system. [0132] In an embodiment, the spray system comprises a first nozzle configured to discharge a full cone spray pattern onto the bottom of the bowl. [0133] In an embodiment, the spray system comprises a second nozzle configured to discharge a hollow cone spray pattern onto an inside surface of the sidewall. [0134] In an embodiment, the oil barrier layer comprises an approximately 1:3 solution of acrylic and water. [0135] A method is also provided for manufacturing a microwave bowl of the type characterized by a substantially flat, circular, bottom region bounded by a circumferential sidewall, comprising the steps of: providing a wire mesh mold approximating the shape of the bowl; preparing an aqueous fiber based slurry comprising at least one of hardwood virgin fiber and softwood virgin fiber; adding an embedded moisture barrier to the slurry; immersing the mold in the slurry; drawing a vacuum across the mold within the slurry until a desired thickness of fiber particles accumulates at a surface of the mold; removing the accumulated particles from the mold; drying and pressing the accumulated particles in a press to thereby form the bowl; transferring the bowl from the press to a coating station; and applying a topical oil barrier layer to at least a portion of the bowl at the coating station, the topical oil barrier layer comprising about 27.5% solids in a water solution. [0136] In an embodiment, the solids comprise acrylate, rice bran wax, pectin, and pea protein. [0137] A microwave bowl may be manufactured using any of the methods described herein. [0138] While the present invention has been described in the context of the foregoing embodiments, it will be appreciated that the invention is not so limited. For example, the various spray systems and nozzle configurations, slurry chemistries, and spray coat chemistries may be adjusted to accommodate additional applications based on the teachings of the present invention. [0139] As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations, nor is it intended to be construed as a model that must be literally duplicated. [0140] While the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing various embodiments of the invention, it should be appreciated that the particular embodiments described above are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. To the contrary, various changes may be made in the function and arrangement of elements described without departing from the scope of the invention.