Title of Invention	" A CONTAINER FOR ROTAINING LIQUID AND /OR FOOD AND A METHOD FOR FORMING THE SAME"
Abstract	A foam thermoplastic cotitainer e.g. cup, bowl 10 molded from expandable thermoplastic particles e.g. expandable polystyrene, has a film made of a thermoplastic resin e.g, solid polystyrene, rubber- modified polystyrene, PET, polyethylene, polypropylene, fused to its inner sidewall surface f5 by heat and pressure to create a barrier to resist the leakage of liquid and food with oil and/or fatry components and to increase the rim atrength of the container. The thermoplastic resin film can be fused to the outer surface of the container for printing 20 purposes and/or to create a barrier and/or can be fused to the base surfaces of the container. The molding machine used to form the foam container is used to fuse the film to the container.

Title of Invention

" A CONTAINER FOR ROTAINING LIQUID AND /OR FOOD AND A METHOD FOR FORMING THE SAME"

Abstract

A foam thermoplastic cotitainer e.g. cup, bowl 10 molded from expandable thermoplastic particles e.g. expandable polystyrene, has a film made of a thermoplastic resin e.g, solid polystyrene, rubber- modified polystyrene, PET, polyethylene, polypropylene, fused to its inner sidewall surface f5 by heat and pressure to create a barrier to resist the leakage of liquid and food with oil and/or fatry components and to increase the rim atrength of the container. The thermoplastic resin film can be fused to the outer surface of the container for printing 20 purposes and/or to create a barrier and/or can be fused to the base surfaces of the container. The molding machine used to form the foam container is used to fuse the film to the container.

Full Text	The present invention relates to a disposable container. More particularly, the present invention 10 relates to a thermoplastic film, which is heat and pressure fused to the inner and/or outer surfaces of the sidewall of a thermoplastic container, and optionally, to the inner and/or outer surfaces of container's base. The container is generally pre- 15 formed via a molding process from expandable thermoplastic particles, e.g. expandable polystyrene particles (EPS). The container is used for holding liquids, such as coffee or foods containing oil and/or fat components such as precooked fat- 20 containing foods, e.g. instant noodles, soups, fried chicken, and the like. 2 . Background Art The manufacture of molded articles, such as 25 containers, i.e, cups, bowls, etc. from expanded thermoplastic particles is well known. The most commonly used thermoplastic particles are expandable polystyrene particles known as EPS. Typically, polystyrene beads are impregnated with a blowing 30 agent, which boils below the softening point of the polystyrene and causes the impregnated beads to expand when they are heated. The formation of molded articles from impregnated polystyrene beads is generally done in 35 two steps. First, the impregnated polystyrene beads 9253 PCT 5 are pre-expanded to a density of from about 2 to 12 pounds per cubic foot. Second, the pre-expanded beads are heated in a closed, mold to further expand the pre- expanded beads to form a fused article haying the shape of the mold. 10 The expandable polystyrene particles used to make foam containers are generally prepared by an aqueous suspension polymerisation process, which results in beads that can be screened to relatively precise bead sizes. Typically, bead diameters are 15 within the range of from about 0,008 to about 0-02 inch. Occasionally, cups are made from particles having bead diameters as high as 0,03 inches. In spite of careful bead sise control, one problem, which continues to plague the container 20 industry, is that after a period of time the EPS containers have a tendency to leak coffee or the oil and/or fat components in food substances carried by the containers. That is, the coffee or the oil and/or fat permeate around the fused polystyrene 25 beads onto the outer surface of the sidewall of the container. The result can be an unsightly stain on the outer surface of the sidewall of the container and/or inconvenience to the holder of the container. Several approaches have evolved over the years 30 directed toward the reduction of leakage in these containers for retaining liquids and/or pre-cooked foods. Amberg et al., U.S. Patent 4,036,675 discloses a container made from foamed plastic material, 35. preferably foamed polystyrene, which is lined on and or both sides with unoriented polyplefin film, 2 5 preferably polypropylene. The film is secured to the foamed plastic base material using as a heat- sensitive adhesive a vinylic polymer or polyamide resin. The film is coated with a wet adhesive and dried before laminating the film to the foam 10 material. Laminating is done by heating the foam material to 250-375ºF, preheating the coated film to lOO-l8OºP, and pressing the coated film surface against the heated foam using a cold platen or roller for 10 to 15 seconds, 15 Sonnenberg U.S. Patent Nos. 4,703,065 and 4,720 ,419 disclose thermoplastic polymer foam cups for retaining coffee that are molded from thermoplastic polymer particles whose surfaces are- coated with a fluorosurfactant before molding. 20 Sonnenberg U.S. Patent No. 4, 785,022 discloses a method for enhancing the coffee retention of molded foam cups, which involves coating the expandable polystyrene particles with various rubber polymers and copolymers. The rubber useful in the 25 invention can be selected from the group consisting of polybutene, polyisobutylene, isobutylene-butene copolymer and butene-ethylene copolymer. Arch, et al. U.S. patent No. 4,798,749 approaches the problem of coffee leakage by 30 replacing conventional blowing agents such as butanes, n-pentane, hexanes, and the halogenated- hydrocarbons with isopentane in the expandable styrene polymer particles. Ikeda, et al., U.S. Patent Mo. 4,698,367 35 discloses expandable thermoplastic resin particles in which the thermoplastic resin in which a 3 9253 PCT 5 copolymer composed of a fluorinated vinyl polymer part and a hydrophi1ic vinyl polymer part covers or is included on the surface or in the surface layer of the expandable thermoplastic particle. These resin particles are useful for producing package 10 containers for oily or fatty foods- Sakoda et al., U.S. Patent No. 6,277,451 B1 is directed to the prevention of oil from penetrating into a vessel obtained from expandable thermoplastic resin beads through molding. This is achieved by 15 coating the surface or the resin beads or incorporating the resin beads with a fluorine- containing block copolymer comprising a fluorine - containing vinyl-type polymer segment derived from- a fluorine-containing vinyl-type monomer and a 20 lipophilic vinyl-type polymer segment derived from a lipophilic vinyl-type monomer. The containers of the above prior art are generally addressed to polystyrene containers, such as cups or bowls. The following patents pertain to 25 paper cups that are either spray coated or that contain a thermoplastic resin film either for heat insulating purposes or for producing a high impermeability to liquids. For example, Suzuki et al., U.S. Patent No. 30 4,206,249 discloses a process for producing a paper container having high impermeability to liquid which comprises spray coating a polymerizable solution containing a prepolynter onto a wall surface of a previously fabricated paper container and 35 irradiating the coated wall with ultraviolet light to effect the setting of the prepolymer on the wall 4 9253 PCT 5 surface of the container. This forms a coating, which is impermeable to liquids, such as water, milk, soft drinks, oils, etc. This 249 patent also teaches in column 2, lines 4 5-62, that there is a lining method in which the interior wall surface of 10 the container is lined with a thermoplastic film. The thermoplastic film is first laminated onto a blank and the blank is formed into a container. lioka, U.S. Patent Flo. 4,435/344 discloses a heat-insulating paper container where the outer and is inner surfaces of the body member are extrusion coated or laminated with a thermoplastic synthetic resin film. The resin film is converted into a formed layer on the paper substrate and then the container is formed. The result is a container with: 20 good thermo-insulation properties. This film preferably is polyethylene but as taught in column 3, lines 50 - 55, this resin film cart be polypropylene, polyvinyl chloride, polystyrene, polyester, nylon and the like. 25 lioka et al . , u.s, Patent No. 5,4 90,631 discloses a heat insulating paper container comprising a body member wherein a thick foamed heat insulating layer is made of a thermoplastic synthetic resin film is formed in the printed area 30 of the outer surface and a less thick foamed heat- insulating layer that can be made of the seme thermoplastic synthetic resin film is formed in the non-printed area of the outer surface. The thermoplastic synthetic resin film is typically; 35 polyethylene. 5 9253 PCT 5 Breining, et al. , U.S. Patent NO. 6,416,829 B2 discloses a heat insulating paper cup where the body member is coated on its outside surface with, a foamed low density polyethylene, and on its inside surface with an unfoamed modified low density 10 polyethylene. None of the containers of the prior art have a thin thermoplastic film fused to the inner and/or outer surfaces of a foam molded container for retaining food items such as coffee, soups, meats, 15 and the like for the purpose of reducing the penetration of the liquid and/or the oil or fatty components in these food items through the foam container. SUMMARY__OF THE INVENTION 20 The invention relates to a container suitable for use in retaining hot liquids such as coffee or water added to food items such as instant soups and/or stews. A foam molded container made from expandable thermoplastic particles is formed, and an 25 extruded or blown thin thermoplastic film is encircled at least ground the inside of the container, and the film is heat fused onto the inner surface of the sidewall of the container. Optionally, a thin thermoplastic film can be 30 encircled around and heat fused onto the outer surface of the sidewall of the container, and optionally, a film can be heat fused to the inner and/or outer surfaces of the base of the container. The resultant container is impervious to leakage 35 and/or stains caused by liquids and/or oily and fatty foods. The film around the outer surface of 6 9253 PCT 5 the sidewall of the container can also be used for labeling and printing purposes. The thermoplastic film is made of a polymer selected from the group consisting of solid polystyrene, rubber modified polystyrene, polymethyl 10 methacrylate, rubber-modified polymethyl methacrylate, polypropylene, polyethylene, polyethylene terephthalate (PET), and mixtures thereof. Additionally, one or more of these polymers can be blerided with a styrene/maleic 15 anhydride copolymer. In the preferred embodiments of the invention, the polymer for the thermoplastic film is selected from the group consisting of solid polystyrene and rubber-modified polystyrene, i.e. a medium impact 20 polystyrene resin, and a high impact polystyrene resin. The high impact polystyrene appears to give the best results. The thickness of the thermoplastic film ranges from about 0.10 mil to about 5.0 mils, and preferably is about 1..0 mil, and 25 extends substantially the depth of the container around the inner and/or outer surfaces of the sidewall of the container. Preferably, the thermoplastic film is fused to the inner and/or outer surfaces of the sidewall of 30 the foam container via the same molding equipment used to form the foam container. The thermoplastic film can optionally be fused to the inner and/or outer surfaces of the base of the formed container. The foam molded container is made of expandable 35 thermoplastic resin beads, and in the preferred 7 5 embodiments, this expandable thermoplastic resin is expandable polystyrene particles (EPS). It is an object of the present invention to provide a thermoplastic foam container that exhibits improved resistance to leak-age and/or stain, and 10 improved mechanical properties, such as improved- rim strength and surface hardness of the container. It is a further object of the present invention to provide a thermoplastic film fused to at least the inner surface of the sidewall of a formed foam 15 container by heat and pressure, and optionally can be fused to the outer surface of the sidewall and/or to the surfaces of the base of the container. It is still a further object of the present invention to provide a thermoplastic container that 20 is suitable for receiving hot liquids, such as coffee, hot water for instant soups, stews, etc and which thermoplastic container with its contents can be reheated in a microwave. 25 DETAILED DESCRIPTION OF THE INVENTION In the invention, 3 foam container, e.g., cups, bowls, and the like is molded from expandable thermoplastic particles. These expandable thermoplastic particles are made front any suitable 30 thermoplastic homopolymer or copolymer. Particularly suitable for use are homopolymers derived from vinyl aromatic monomers including styrene, isopropylstyrene, alpha-methylstyrene, nuclear methylstyrenes, chlorostymers, tert- 35 butylstyrene, and the like, as well as copolymers prepared by the copolymeriation of at least one. 9253 PCT 5 vinyl aromatic monomer with monomers such as divinylbenzene, butadiene, alkyl methacrylates, alkyl acrylates, acrylonitrile, and maleic anhydride, wherein the vinyl aromatic monomer is present in at lease 50% by weight of the copolymer. 10 Styrenic polymers are preferred, particularly polystyrene. However, other suitable polymers may be used, such as polyolefins (e.g. polyethylene, polypropylene}, and polycarbonates (polyphenylene oxides, and mixtures thereof, 15 In the preferred embodiments; the expandable thermoplastic particles are expandable polystyrene (EPS) particles. These particles can be in the form of beads, granules, or other particles convenient for the expansion and molding operations. Particles 20 polymerized in an aqueous suspension process are essentially spherical and are preferred for molding the foam container of the invention. These particles are screened so that their size ranges from about 0,008 to about 0.02 inch. 25 These expandable thermoplastic particles are impregnated using any conventional method with a suitable blowing agent. For example, the impregnation can be achieved by adding the blowing agent to the aqueous suspension during the 30 polymerization of the polymer, or alternatively by re-suspending the polymer particles in an aqueous medium and then incorporating the blowing agent as taxtght in U.S. Patent No. 2,963,692 to D. Alelio. Any gaseous material or material which will produce 35 gases on heating can be used as the blowing acfent. Conventional blowing agents include aliphatic 9253 PCT 5 hydrocarbons containing 4 to 6 carbon atoms in the molecule, such as butanes, pentanes, hexcanes, and the halogenated hydrocarbons, e.g. CFC's and HCFC'S, which boil at a temperature below the softening point of the polymer chosen. Mixtures of these 10 aliphatic hydrocarbons blowing agents can also be used. Alternatively, water can be blended with these aliphatic hydrocarbons blowing agents or water can be used as the Sole blowing agent as taught in U.S. 15 Patent Nos. 6, 127,432; 6,160,02-7; and 6,242,540 assigned to NOVA, Chemicals (International) S.A. In these patents, water-retaining agents are used. The weight percentage of water for use as the blowing agent can range from 1 to 20%. The texts of U.S. 20 Patent Nos. 6,127,4 39, 6,16 0,02 7 and 6, 242, 54 0 are incorporated herein by reference. The imprecated thermoplastic particles are generally pre-expanded to a density of from about 2 to about 12 pounds per cubic food. The pre- 25 expansion step is conventionally carried out by heating the impregnated beads via any conventional heating medium, such as steam, hot air, hot water, or radiant heat. One generally accepted, method for accomplishing the pre-expansion of impregnated 30 thermoplastic particles is taught in U.S. Patent NO- 3,023,175 to Rodman. The impregnated thermoplastic particles can be foamed cellular polymer particles as taught in Arch et al. U.S. Patent Application Serial No. 10/021,716 35 assigned to NOVA Chemicals Inc, the teachings of which are incorporated herein by reference. The 10 9253 PCT 5 foamed cellular particles are preferably polystyrene that are pre-expanded to a density of from about 12.5 to about 34.3 pounds per cubic foot, and contain a volatile blowing agent level less than 6-0 weight percent, preferably ranging from, about 2.0 wt 10 % to about 5.0 wt %, and more preferably ranging from about 2.5 wt % to about 3,5 wt % based on the weight of the polymer. In a conventional manner, the pre-expanded particles or "pre-puff" are beated in a closed mold 15 to further expand the pre-puff and to form the container of the invention. The thermoplastic film is made of a polymer selected from the group consisting of solid polystyrene, rubber modified polystyrene, polymethyl 20 methacrylate, rubber-modified polymethyl methacrylate, polypropylene, polyethylene, polyethylene terephthalate (PET), and mixtures thereof. Additionally, one of the preceding polymers can be blended with a styrene/maleic 25 anhydride copolymer. In the preferred embodiments of the invention, the polymer for the thetmoplastic film is selected front the group consisting of solid polystyrene and rubber-modified polystyrene, i..e. a. medium impact polystyrene resin and a high impact 30 polystyrene resin. Polystyrene is a high molecular weight linear polymer produced by polymerising styrene. When made from only the styrene monomer, the resulting polymer has a glass transition temperature of about 100ºC 35 and is brittle, showing very poor strength i.e. elongation to rupture characteristics. It is known 11 9253 PCT 5 that the strength characteristics can be improved by incorporating rubber modifiers such as butadiene rubber, which product is referred to as a medium impact polystyrene or a high impact polystyrene (HIPS), depending on the weight percent of rubber 10 polymer incorporated into the styrene. for the medium impact polyscyrene, the polystyrene ranges from about 95 to 98 weight percent and the rubber polymer ranges from about 2 to about 5 weight percent, based on the weight of the polystyrene 15 resin. For the high impact polystyrene, the polystyrene ranges from about 35 to about 95 weight percent and the rubber polymer ranges from about 5 to about 15 weight percent, based on the weight of the polystyrene resin. 20 The process for making "HIPS" is well known to Chose skilled in the art. Such known processes are exemplified in U.S. Patent No. 3,903,202 and U.S. Patent 4,146,559, the teachings of which are incorporated herein by reference. The rubber is 25 "dissolved" in the styrene monomer (actually the rubber is infinitely swollen with the monomer). The resulting "solution" is fed to a reactor and with the use of a suitable initiator system polymerization occurs typically under shear. During 30 the polymerization, the styrene is grafted to the rubber. The grafting is thought to be necessary to provide the higher modulus and impact strength, as compared to simple blends of polystyrene and butadiene rubbers. When the conversion of the 35 styrene is about equal to the weight percent of the rubber in the system the phases invert, i.e. the 12 9253 PCT 5 styrene/styrene polymer phase becomes continuous and the rubber phase becomes discontinuous. After phase inversion the polymer is finished in a manner essentially similar to that for finishing polystyrene. 10 Preferably, the amount of rubber used in the high impact polystyrene film of the invention is about 8 weight percent and that used in medium impact polystyrene film is about 3 weight percent, based on the weight of the polystyrene resin. 15 Suitable rubbers for modifying the polystyrene are natural rubber, polybutadiene and its copolymers with styrene or other comonamers , i.e. styrene- butadiene copolymer rubber, polyisoprene and its copolymers with styrene or other comonomers, acrylic 20 rubbers, EPDM rubbers, polybutylene and so on. Preferably, the rubber is polybutadiene or styrene- butadiene copolymer rubber. The particle distribution of the rubber in the polystyrene matrix is preferably unimodal. The 25 average rubber particle size ranges from about 0.5. microns to about 3 microns in size; preferably from about 1.0 micron to about 2.5 microns , more preferably from about 1 to about 2.0 micron; and most preferably from about 1.5 micron, to about 2.0 _30 microns. As is known to those skilled in the art, the particle sise of the rubber particles are generally controlled by the applied shear rate, heat, pressure, or a combination of these factors, during the stage of inversion of the polymerization 35 when polystyrene becomes the continuous phase. 12 5 Suitable rubber modified polystyrene particles are commercially available. Preferred among the commercial products of medium and high impact polystyrene are 5500, 5210, 4211, all available from NOVA Chemicals inc., 5100 Bainbridge Boulevard, to Chesapeake, VA 23320. The rubber modified polystyrene particles may be in bead or pellet form and may include the cystomary ingredients and additives, such as pigments, colorants, plasticizers, mold release 15 agents, stabilizers, ultraviolet light absorbers, and so on. Typical pigments include, without limitation, inorganic pigments such as carbon black, zine oxide, titanium dioxide, and iron oxide, as well as organic pigmente such as quinacridone reds 20 and violets and copper phthalocyanine blues and greens. In a further preferred embodiment of the invention, the thermoplastic film is comprised of general solid polystyrene, which also is available 25 from NOVA Chemicals Inc., Beaver Valley Plant, Monaca, Pennsylvania. The thermoplastic film may be formed via an extrusion process or a blow molding process. Molding conditions may be the same as conditions 30 usually employed for molding impact modified polystyrenes. Preferably, the thermoplastic film of the invention is extruded from a slot or a circulate die. Preferably, the thermoplastic film has an IZOD 35 impact value ranging from about 50 to about 100 J/M 14 9253 PCT 5 and an impact resistance greater than 1. 0 ft- lb/inch. The thermoplastic container can be a polystyrene cup that is fabricated by a conventional cup-forming machine that has an inner shell and an 10 outer shell, for example, Cup Production MODEL 6- VLC-125 machine, made by Autonational B.V. In one embodiment of the invention, after the cup or cups are molded, the thermoplastic film is formed into a cylinder and inserted into the cup, 15 which, in turn is carried by a mandrel . The inner shell is inserted into the cup, and heat and pressure is applied to the thermoplastic film to fuse the film to the inner surface of the side wall of the cup. The pressures for the inner shell against 20 the thermoplastic film ranges from shout 20 to about 80 pounds per square inch, preferably from about 30 to about 50 pounds per square inch (psi). The fabrication rate for the film fusing operation for a single machine producing 10-ounce 23 cups ranges from about 18 to 120 cups per minute. Several machines can be used to increase the production rate. Heat is applied to the thermoplastic film by means of steam in order to melt the thermoplastic film and the adjacent 30 polystyrene beads so that a cohesive effect occurs. between the inner surface of the sidewall of the cup and the thermoplastic film. The temperature and time for this cohesion to occur may vary, for example., from about 60°C to about 120ºC for about 13 35 to about 20 seconds. 15 9253 PCT 5 IC has been found that the thermoplastic film also increases the rim strength of the container, which, in effect, increases the overall strength of the container. The rim strength is a measure of the force required (in kilograms) to cause the rim to 10 crumble a one-fourth inch displacement from the opened edge of the container. Other embodiments of the invention involve the thermoplastic- film being fused to the inxier and/or outer surfaces of the sidewall and/or fused to the 16 inner and/or outer surfaces of the base of the container. The invention is further illustrated, but not limited by, the following examples wherein all parts and percentages are by weight unless otherwise 20 specified. Examples Example 1 This example illustrates the preparation of 25 thermoplastic film lined containers. The NOVA Chemicals F2T1TU (expandable polystyrene) cup beads blended with zinc stearate were pre-expanded in an 11-gallon Rodman Steam pre-expandar (Artisan Industries Inc-l at atmospheric pressure. The pre- 30 expansion was operated batch wise. The weight of the cup beads (i.e. 3.5 lbs.) was adjusted to make a pre-puff with a density ranging between 2,6 - 3.6 pounds per cubic foot (pcf) . The newly prepared pre- puff was air dried for 5 minutes to remove the 35 moisture and was allowed to age for about 4 hours before molding. 16 9253 PCT 5 Six-ounce standard cups using different density aged pre-puff besds were molded. The steam header pressure used was 80 pounds per square inch (psi) and the total cycle time was in the range of 7.50 to 8.25 seconds. The molded cups were allowed to age 10 overnight. Pre-cut extruded polystyrene film (1.0 mil thickl wade from NOVA. Chemical PS 2110 (general solid polystyrene) resin was fused onto the inner surface of the sidewall of the cups in the same 15 molder used for forming the cups. The header steam pressure used in the film fusion process was 45 pounder per square inch and the total cycle time was 5.55 seconds. The film-lined containers were stored overnight before testing. 20 The cups with the varying density pre-puff beads, i.e. 3.47, 3.54 , 3.21, and 2.61 pcf, were tested by tha following method: Spicy oil at room temperature was poured into each container up to around 80% of the cup's height. The outside wall of 25 each container containing the spicy oil was observed for oil stains and leakage every 10 minutes over the first l.5 hours., every 20 minutes in the time period from 1.5 hours to 6 hours, and, then, every hour up to a total of 48 hours. 30 The average time failure (ATF) for each cup group sampling was calculated by adding the time to failure for each container, and dividing the total time by the number of containers tested. Typically, ten cups of each group sampling were tested. The 35 maximum ATP value of 48 hours represents that none of the cups for each cup group sampling exhibited 17 9253 PCT 5 any stain or leakage. The minimum ATP value of 0.17 hours represents that all of the cups in. each of cup group sampling failed within the first 10 minutes. Each cup in each group sampling was tested for rim strength with and without a thermoplastic film 10 and the average force was recorded. Ten cups were tested in each group sampling. The results for the oil retention and the rim. strength are shown in Table l, As indicated in Table 1, the cup samples with the thermoplastic film of 15 the invention have an increased ATF and rim strength compared to the cup sample without the thermoplastic film. 20) Example 2 The oil retention testing and the rim strength testing cor cups with a pre-puff density of 3.4 7 pcf were performed in a manner similar to that of Example 1. These results are shown in Table 2. The 25 polystyrene film was similar to that used in Example l and its thickness varied as shown in Table 2 . As indicated in Table 2, the cup samples with the thermoplastic film of the invention have an 18 5 increased ATF and rim strength compared to the cup samples without the thermoplastic film. Example 3 10 The oil retention testing and the rim strength testing for cups with a pre-puff density of 3.50 pcf were performed in a manner similar to that of Example 1. The thermoplastic film was similar to that used in Example 1 and was either extruded or 15 blown as indicated in Table 3 . The volume of the- EPS cups was changed from 6 ounces to 16 ounces. The: results are shown in Table 3 . The samples with the thermoplastic film fabricated via an extrusion or a blown process have comparable testing results, 20 Also, the samples with the thermoplastic film of the invention regardless of the process for making the thermoplastic film have an increased ATF and rim strength compared to the samples without the thermoplastic film. 19 9253 PCT Example 4 In this Example, the polystyrene resin film was replaced with the thermoplastic materials indicated 10 chersin. NOVA PS 3500, 4211, 5500, and 5102 are the medium and high impact polystyrenes, all of which are discussed hereinabove. As is indicated in Table 4, the cup samples, with the thermoplastic film fabricated from the different thermoplastic 15 materials have comparable ATF and rim strength values. The cups with the fused thermoplastic film of 20 the above Examples have a generally uniform "rough" pr "bumpy" inner sidewall surface. This is due in part to the fact that the film material when fused against the sidewall of the cup covers the voids formed by the expanded polystyrene beads during the 25 mold processing of the cups and the applied temperature for this "fusing" process causes the expanded polystyrene beads to expand even further. 20 9253 PCT 5 The thermoplastic container is used' for retaining pre-packaged foods, e.g. instant noodles, soups, stews, chicken that are sold an the shelves in the grocery stores. The container can be placed in the freezer, or in the microwave for reheating 10 purposes without lessening the integrity of the container. While the present invention has been set forth in terms of specific embodiments thereof, it will be understood in view of the instant disclosure that 15 numerous variations upon the invention are now enabled yet reside within the scope of the invention. Accordingly, the invention is to be broadly construed and limited only by the scope and spirit of the claims now appended hereto. 20 21 9253 PCT 5 WHAT IS CLAIMED IS: 1. A container for retaining liquid and/or food that contains oil and/or fatty components, comprising: a foam molded thermoplastic container having a 10 sidewall with an inner surface and an outer surface and a base with an inner surface and an outer surface; and a thermoplastic film fused to at least one of said, inner surface or said outer surface of said 15 sidewall of said foam molded thermoplastic container for making said container resistant to the penetration of said, liquid and/or said oil and/or fat components of said food through said sidewall of said container. 20 2. A container of claim 1 wherein said foam molded thermoplastic container is made from expandable thermoplastic- particles. 3. A container of claim 2 wherein said expandable thermoplastic particles are expandable polystyrene 25 particles. 4. A container of claim 1 wherein said thermoplastic film is made of a polymer selected form the group consisting of solid polystyrene, rubber modified polystyrene, polymethyl 30 methacrylate, polypropylene, polyethylene, polyethylene terephthalate (PET), and mixtures thereof. 3. A container of claim 4 wherein said thermoplastic film is made of a polymer selected 35 from the group consisting of solid polystyrene and rubber modified polystyrene. 22 9253 PCT 5 6. A container of claim 5 wherein said thermoplastic film is made of solid polystyrene. 7. A container of claim l wherein said thermoplastic film has a thickness ranging from about 0.10 mil to about 5.0 mils. 10 B. A container of claim 1 wherein said thermoplastic film is fused to said inner surface of said sidewall of said container. 9. A container of claim 1 wherein said- thermoplastic film is fused to said outer surface of 13 said sidewall of said container. 10. A container of claim 1 wherein said thermoplastic film is fused, to said base of said. container. 11 . A container of claim 1 wherein said 20 thermoplastic film is produced through an extrusion process. 12. A container of claim l wherein said thermoplastic film is produced through a blowing process. 25 13. A method for forming a container for holding liquid and/or foods containing oil and/or fatty components, the steps comprising: forming a foam thermoplastic container having a sidewall witn an inner surface and an outer 30 surface and a base with an inner surface and an outer surface, and. fusing a thermoplastic film made of thermoplastic resin to at least one of said inner surface and said outer surface of said sidewall of 33 said container to make said container resistant to the penetration of said liquid and/or said oil 23 9253 PCT 5 and/or fat components of said food through said sidewall of said container 14. A method of claim 13 wherein said fusing comprises the application of heat at a temperature ranging from about 60ºC to about 12O°C for about 5 10 to about 20 seconds and the application of pressure to said thermoplastic film ranging from about 20 to about 80 pounds per square inch (psi). 15. A method of claim 13 wherein and foam thermoplastic container is fabricated via a 15 container machine, the steps further comprising; fusing said thermoplastic film to said one of said inner surface and said outer surface of said sidewall of said container via the same machine used for fabricating said thermoplastic container. 20 16. A method of claim 13 the steps further comprising. fusing a thermoplastic film roads of thermoplastic resin to said inner surface of said sidewall of said container. 25 17. A method of claim 13 the steps further comprising: fusing a thermoplastic film made of thermoplastic resin to said outer surface of said sidewall of said container. 30 18, A methcd of claim 13 the steps further comprising; fusing a thermoplastic film made of thermoplastic resin to said base of said container. A foam thermoplastic cotitainer e.g. cup, bowl 10 molded from expandable thermoplastic particles e.g. expandable polystyrene, has a film made of a thermoplastic resin e.g, solid polystyrene, rubber- modified polystyrene, PET, polyethylene, polypropylene, fused to its inner sidewall surface f5 by heat and pressure to create a barrier to resist the leakage of liquid and food with oil and/or fatry components and to increase the rim atrength of the container. The thermoplastic resin film can be fused to the outer surface of the container for printing 20 purposes and/or to create a barrier and/or can be fused to the base surfaces of the container. The molding machine used to form the foam container is used to fuse the film to the container.

Full Text

The present invention relates to a disposable
container. More particularly, the present invention
10 relates to a thermoplastic film, which is heat and
pressure fused to the inner and/or outer surfaces of
the sidewall of a thermoplastic container, and
optionally, to the inner and/or outer surfaces of
container's base. The container is generally pre-
15 formed via a molding process from expandable
thermoplastic particles, e.g. expandable polystyrene
particles (EPS). The container is used for holding
liquids, such as coffee or foods containing oil
and/or fat components such as precooked fat-
20 containing foods, e.g. instant noodles, soups, fried
chicken, and the like.
2 . Background Art
The manufacture of molded articles, such as
25 containers, i.e, cups, bowls, etc. from expanded
thermoplastic particles is well known. The most
commonly used thermoplastic particles are expandable
polystyrene particles known as EPS. Typically,
polystyrene beads are impregnated with a blowing
30 agent, which boils below the softening point of the
polystyrene and causes the impregnated beads to
expand when they are heated.
The formation of molded articles from
impregnated polystyrene beads is generally done in
35 two steps. First, the impregnated polystyrene beads

9253 PCT
5 are pre-expanded to a density of from about 2 to 12
pounds per cubic foot. Second, the pre-expanded
beads are heated in a closed, mold to further expand
the pre- expanded beads to form a fused article
haying the shape of the mold.
10 The expandable polystyrene particles used to
make foam containers are generally prepared by an
aqueous suspension polymerisation process, which
results in beads that can be screened to relatively
precise bead sizes. Typically, bead diameters are
15 within the range of from about 0,008 to about 0-02
inch. Occasionally, cups are made from particles
having bead diameters as high as 0,03 inches.
In spite of careful bead sise control, one
problem, which continues to plague the container
20 industry, is that after a period of time the EPS
containers have a tendency to leak coffee or the oil
and/or fat components in food substances carried by
the containers. That is, the coffee or the oil
and/or fat permeate around the fused polystyrene
25 beads onto the outer surface of the sidewall of the
container. The result can be an unsightly stain on
the outer surface of the sidewall of the container
and/or inconvenience to the holder of the container.
Several approaches have evolved over the years
30 directed toward the reduction of leakage in these
containers for retaining liquids and/or pre-cooked
foods.
Amberg et al., U.S. Patent 4,036,675 discloses
a container made from foamed plastic material,
35. preferably foamed polystyrene, which is lined on and
or both sides with unoriented polyplefin film,
2

5 preferably polypropylene. The film is secured to
the foamed plastic base material using as a heat-
sensitive adhesive a vinylic polymer or polyamide
resin. The film is coated with a wet adhesive and
dried before laminating the film to the foam
10 material. Laminating is done by heating the foam
material to 250-375ºF, preheating the coated film to
lOO-l8OºP, and pressing the coated film surface
against the heated foam using a cold platen or
roller for 10 to 15 seconds,
15 Sonnenberg U.S. Patent Nos. 4,703,065 and
4,720 ,419 disclose thermoplastic polymer foam cups
for retaining coffee that are molded from
thermoplastic polymer particles whose surfaces are-
coated with a fluorosurfactant before molding.
20 Sonnenberg U.S. Patent No. 4, 785,022 discloses
a method for enhancing the coffee retention of
molded foam cups, which involves coating the
expandable polystyrene particles with various rubber
polymers and copolymers. The rubber useful in the
25 invention can be selected from the group consisting
of polybutene, polyisobutylene, isobutylene-butene
copolymer and butene-ethylene copolymer.
Arch, et al. U.S. patent No. 4,798,749
approaches the problem of coffee leakage by
30 replacing conventional blowing agents such as
butanes, n-pentane, hexanes, and the halogenated-
hydrocarbons with isopentane in the expandable
styrene polymer particles.
Ikeda, et al., U.S. Patent Mo. 4,698,367
35 discloses expandable thermoplastic resin particles
in which the thermoplastic resin in which a
3

9253 PCT
5 copolymer composed of a fluorinated vinyl polymer
part and a hydrophi1ic vinyl polymer part covers or
is included on the surface or in the surface layer
of the expandable thermoplastic particle. These
resin particles are useful for producing package
10 containers for oily or fatty foods-
Sakoda et al., U.S. Patent No. 6,277,451 B1 is
directed to the prevention of oil from penetrating
into a vessel obtained from expandable thermoplastic
resin beads through molding. This is achieved by
15 coating the surface or the resin beads or
incorporating the resin beads with a fluorine-
containing block copolymer comprising a fluorine -
containing vinyl-type polymer segment derived from- a
fluorine-containing vinyl-type monomer and a
20 lipophilic vinyl-type polymer segment derived from a
lipophilic vinyl-type monomer.
The containers of the above prior art are
generally addressed to polystyrene containers, such
as cups or bowls. The following patents pertain to
25 paper cups that are either spray coated or that
contain a thermoplastic resin film either for heat
insulating purposes or for producing a high
impermeability to liquids.
For example, Suzuki et al., U.S. Patent No.
30 4,206,249 discloses a process for producing a paper
container having high impermeability to liquid which
comprises spray coating a polymerizable solution
containing a prepolynter onto a wall surface of a
previously fabricated paper container and
35 irradiating the coated wall with ultraviolet light
to effect the setting of the prepolymer on the wall
4

9253 PCT
5 surface of the container. This forms a coating,
which is impermeable to liquids, such as water,
milk, soft drinks, oils, etc. This 249 patent also
teaches in column 2, lines 4 5-62, that there is a
lining method in which the interior wall surface of
10 the container is lined with a thermoplastic film.
The thermoplastic film is first laminated onto a
blank and the blank is formed into a container.
lioka, U.S. Patent Flo. 4,435/344 discloses a
heat-insulating paper container where the outer and
is inner surfaces of the body member are extrusion
coated or laminated with a thermoplastic synthetic
resin film. The resin film is converted into a
formed layer on the paper substrate and then the
container is formed. The result is a container with:
20 good thermo-insulation properties. This film
preferably is polyethylene but as taught in column
3, lines 50 - 55, this resin film cart be
polypropylene, polyvinyl chloride, polystyrene,
polyester, nylon and the like.
25 lioka et al . , u.s, Patent No. 5,4 90,631
discloses a heat insulating paper container
comprising a body member wherein a thick foamed heat
insulating layer is made of a thermoplastic
synthetic resin film is formed in the printed area
30 of the outer surface and a less thick foamed heat-
insulating layer that can be made of the seme
thermoplastic synthetic resin film is formed in the
non-printed area of the outer surface. The
thermoplastic synthetic resin film is typically;
35 polyethylene.
5

9253 PCT
5 Breining, et al. , U.S. Patent NO. 6,416,829 B2
discloses a heat insulating paper cup where the body
member is coated on its outside surface with, a
foamed low density polyethylene, and on its inside
surface with an unfoamed modified low density
10 polyethylene.
None of the containers of the prior art have a
thin thermoplastic film fused to the inner and/or
outer surfaces of a foam molded container for
retaining food items such as coffee, soups, meats,
15 and the like for the purpose of reducing the
penetration of the liquid and/or the oil or fatty
components in these food items through the foam
container.
SUMMARY__OF THE INVENTION
20 The invention relates to a container suitable
for use in retaining hot liquids such as coffee or
water added to food items such as instant soups
and/or stews. A foam molded container made from
expandable thermoplastic particles is formed, and an
25 extruded or blown thin thermoplastic film is
encircled at least ground the inside of the
container, and the film is heat fused onto the inner
surface of the sidewall of the container.
Optionally, a thin thermoplastic film can be
30 encircled around and heat fused onto the outer
surface of the sidewall of the container, and
optionally, a film can be heat fused to the inner
and/or outer surfaces of the base of the container.
The resultant container is impervious to leakage
35 and/or stains caused by liquids and/or oily and
fatty foods. The film around the outer surface of
6

9253 PCT
5 the sidewall of the container can also be used for
labeling and printing purposes.
The thermoplastic film is made of a polymer
selected from the group consisting of solid
polystyrene, rubber modified polystyrene, polymethyl
10 methacrylate, rubber-modified polymethyl
methacrylate, polypropylene, polyethylene,
polyethylene terephthalate (PET), and mixtures
thereof. Additionally, one or more of these
polymers can be blerided with a styrene/maleic
15 anhydride copolymer.
In the preferred embodiments of the invention,
the polymer for the thermoplastic film is selected
from the group consisting of solid polystyrene and
rubber-modified polystyrene, i.e. a medium impact
20 polystyrene resin, and a high impact polystyrene
resin. The high impact polystyrene appears to give
the best results. The thickness of the
thermoplastic film ranges from about 0.10 mil to
about 5.0 mils, and preferably is about 1..0 mil, and
25 extends substantially the depth of the container
around the inner and/or outer surfaces of the
sidewall of the container.
Preferably, the thermoplastic film is fused to
the inner and/or outer surfaces of the sidewall of
30 the foam container via the same molding equipment
used to form the foam container. The thermoplastic
film can optionally be fused to the inner and/or
outer surfaces of the base of the formed container.
The foam molded container is made of expandable
35 thermoplastic resin beads, and in the preferred
7

5 embodiments, this expandable thermoplastic resin is
expandable polystyrene particles (EPS).
It is an object of the present invention to
provide a thermoplastic foam container that exhibits
improved resistance to leak-age and/or stain, and
10 improved mechanical properties, such as improved- rim
strength and surface hardness of the container.
It is a further object of the present invention
to provide a thermoplastic film fused to at least
the inner surface of the sidewall of a formed foam
15 container by heat and pressure, and optionally can
be fused to the outer surface of the sidewall and/or
to the surfaces of the base of the container.
It is still a further object of the present
invention to provide a thermoplastic container that
20 is suitable for receiving hot liquids, such as
coffee, hot water for instant soups, stews, etc and
which thermoplastic container with its contents can
be reheated in a microwave.
25 DETAILED DESCRIPTION OF THE INVENTION
In the invention, 3 foam container, e.g., cups,
bowls, and the like is molded from expandable
thermoplastic particles. These expandable
thermoplastic particles are made front any suitable
30 thermoplastic homopolymer or copolymer.
Particularly suitable for use are homopolymers
derived from vinyl aromatic monomers including
styrene, isopropylstyrene, alpha-methylstyrene,
nuclear methylstyrenes, chlorostymers, tert-
35 butylstyrene, and the like, as well as copolymers
prepared by the copolymeriation of at least one.

9253 PCT

5 vinyl aromatic monomer with monomers such as
divinylbenzene, butadiene, alkyl methacrylates,
alkyl acrylates, acrylonitrile, and maleic
anhydride, wherein the vinyl aromatic monomer is
present in at lease 50% by weight of the copolymer.
10 Styrenic polymers are preferred, particularly
polystyrene. However, other suitable polymers may
be used, such as polyolefins (e.g. polyethylene,
polypropylene}, and polycarbonates (polyphenylene
oxides, and mixtures thereof,
15 In the preferred embodiments; the expandable
thermoplastic particles are expandable polystyrene
(EPS) particles. These particles can be in the form
of beads, granules, or other particles convenient
for the expansion and molding operations. Particles
20 polymerized in an aqueous suspension process are
essentially spherical and are preferred for molding
the foam container of the invention. These
particles are screened so that their size ranges
from about 0,008 to about 0.02 inch.
25 These expandable thermoplastic particles are
impregnated using any conventional method with a
suitable blowing agent. For example, the
impregnation can be achieved by adding the blowing
agent to the aqueous suspension during the
30 polymerization of the polymer, or alternatively by
re-suspending the polymer particles in an aqueous
medium and then incorporating the blowing agent as
taxtght in U.S. Patent No. 2,963,692 to D. Alelio.
Any gaseous material or material which will produce
35 gases on heating can be used as the blowing acfent.
Conventional blowing agents include aliphatic

9253 PCT
5 hydrocarbons containing 4 to 6 carbon atoms in the
molecule, such as butanes, pentanes, hexcanes, and
the halogenated hydrocarbons, e.g. CFC's and HCFC'S,
which boil at a temperature below the softening
point of the polymer chosen. Mixtures of these
10 aliphatic hydrocarbons blowing agents can also be
used.
Alternatively, water can be blended with these
aliphatic hydrocarbons blowing agents or water can
be used as the Sole blowing agent as taught in U.S.
15 Patent Nos. 6, 127,432; 6,160,02-7; and 6,242,540
assigned to NOVA, Chemicals (International) S.A. In
these patents, water-retaining agents are used. The
weight percentage of water for use as the blowing
agent can range from 1 to 20%. The texts of U.S.
20 Patent Nos. 6,127,4 39, 6,16 0,02 7 and 6, 242, 54 0 are
incorporated herein by reference.
The imprecated thermoplastic particles are
generally pre-expanded to a density of from about 2
to about 12 pounds per cubic food. The pre-
25 expansion step is conventionally carried out by
heating the impregnated beads via any conventional
heating medium, such as steam, hot air, hot water,
or radiant heat. One generally accepted, method for
accomplishing the pre-expansion of impregnated
30 thermoplastic particles is taught in U.S. Patent NO-
3,023,175 to Rodman.
The impregnated thermoplastic particles can be
foamed cellular polymer particles as taught in Arch
et al. U.S. Patent Application Serial No. 10/021,716
35 assigned to NOVA Chemicals Inc, the teachings of
which are incorporated herein by reference. The
10

9253 PCT
5 foamed cellular particles are preferably polystyrene
that are pre-expanded to a density of from about
12.5 to about 34.3 pounds per cubic foot, and
contain a volatile blowing agent level less than 6-0
weight percent, preferably ranging from, about 2.0 wt
10 % to about 5.0 wt %, and more preferably ranging
from about 2.5 wt % to about 3,5 wt % based on the
weight of the polymer.
In a conventional manner, the pre-expanded
particles or "pre-puff" are beated in a closed mold
15 to further expand the pre-puff and to form the
container of the invention.
The thermoplastic film is made of a polymer
selected from the group consisting of solid
polystyrene, rubber modified polystyrene, polymethyl
20 methacrylate, rubber-modified polymethyl
methacrylate, polypropylene, polyethylene,
polyethylene terephthalate (PET), and mixtures
thereof. Additionally, one of the preceding
polymers can be blended with a styrene/maleic
25 anhydride copolymer. In the preferred embodiments
of the invention, the polymer for the thetmoplastic
film is selected front the group consisting of solid
polystyrene and rubber-modified polystyrene, i..e. a.
medium impact polystyrene resin and a high impact
30 polystyrene resin.
Polystyrene is a high molecular weight linear
polymer produced by polymerising styrene. When made
from only the styrene monomer, the resulting polymer
has a glass transition temperature of about 100ºC
35 and is brittle, showing very poor strength i.e.
elongation to rupture characteristics. It is known
11

9253 PCT
5 that the strength characteristics can be improved by
incorporating rubber modifiers such as butadiene
rubber, which product is referred to as a medium
impact polystyrene or a high impact polystyrene
(HIPS), depending on the weight percent of rubber
10 polymer incorporated into the styrene. for the
medium impact polyscyrene, the polystyrene ranges
from about 95 to 98 weight percent and the rubber
polymer ranges from about 2 to about 5 weight
percent, based on the weight of the polystyrene
15 resin. For the high impact polystyrene, the
polystyrene ranges from about 35 to about 95 weight
percent and the rubber polymer ranges from about 5
to about 15 weight percent, based on the weight of
the polystyrene resin.
20 The process for making "HIPS" is well known to
Chose skilled in the art. Such known processes are
exemplified in U.S. Patent No. 3,903,202 and U.S.
Patent 4,146,559, the teachings of which are
incorporated herein by reference. The rubber is
25 "dissolved" in the styrene monomer (actually the
rubber is infinitely swollen with the monomer). The
resulting "solution" is fed to a reactor and with
the use of a suitable initiator system
polymerization occurs typically under shear. During
30 the polymerization, the styrene is grafted to the
rubber. The grafting is thought to be necessary to
provide the higher modulus and impact strength, as
compared to simple blends of polystyrene and
butadiene rubbers. When the conversion of the
35 styrene is about equal to the weight percent of the
rubber in the system the phases invert, i.e. the
12

9253 PCT
5 styrene/styrene polymer phase becomes continuous and
the rubber phase becomes discontinuous. After phase
inversion the polymer is finished in a manner
essentially similar to that for finishing
polystyrene.
10 Preferably, the amount of rubber used in the
high impact polystyrene film of the invention is
about 8 weight percent and that used in medium
impact polystyrene film is about 3 weight percent,
based on the weight of the polystyrene resin.
15 Suitable rubbers for modifying the polystyrene
are natural rubber, polybutadiene and its copolymers
with styrene or other comonamers , i.e. styrene-
butadiene copolymer rubber, polyisoprene and its
copolymers with styrene or other comonomers, acrylic
20 rubbers, EPDM rubbers, polybutylene and so on.
Preferably, the rubber is polybutadiene or styrene-
butadiene copolymer rubber.
The particle distribution of the rubber in the
polystyrene matrix is preferably unimodal. The
25 average rubber particle size ranges from about 0.5.
microns to about 3 microns in size; preferably from
about 1.0 micron to about 2.5 microns , more
preferably from about 1 to about 2.0 micron; and
most preferably from about 1.5 micron, to about 2.0
_30 microns. As is known to those skilled in the art,
the particle sise of the rubber particles are
generally controlled by the applied shear rate,
heat, pressure, or a combination of these factors,
during the stage of inversion of the polymerization
35 when polystyrene becomes the continuous phase.
12

5 Suitable rubber modified polystyrene particles
are commercially available. Preferred among the
commercial products of medium and high impact
polystyrene are 5500, 5210, 4211, all available from
NOVA Chemicals inc., 5100 Bainbridge Boulevard,
to Chesapeake, VA 23320.
The rubber modified polystyrene particles may
be in bead or pellet form and may include the
cystomary ingredients and additives, such as
pigments, colorants, plasticizers, mold release
15 agents, stabilizers, ultraviolet light absorbers,
and so on. Typical pigments include, without
limitation, inorganic pigments such as carbon black,
zine oxide, titanium dioxide, and iron oxide, as
well as organic pigmente such as quinacridone reds
20 and violets and copper phthalocyanine blues and
greens.
In a further preferred embodiment of the
invention, the thermoplastic film is comprised of
general solid polystyrene, which also is available
25 from NOVA Chemicals Inc., Beaver Valley Plant,
Monaca, Pennsylvania.
The thermoplastic film may be formed via an
extrusion process or a blow molding process.
Molding conditions may be the same as conditions
30 usually employed for molding impact modified
polystyrenes. Preferably, the thermoplastic film of
the invention is extruded from a slot or a circulate
die.
Preferably, the thermoplastic film has an IZOD
35 impact value ranging from about 50 to about 100 J/M
14

9253 PCT
5 and an impact resistance greater than 1. 0 ft-
lb/inch.
The thermoplastic container can be a
polystyrene cup that is fabricated by a conventional
cup-forming machine that has an inner shell and an
10 outer shell, for example, Cup Production MODEL 6-
VLC-125 machine, made by Autonational B.V.
In one embodiment of the invention, after the
cup or cups are molded, the thermoplastic film is
formed into a cylinder and inserted into the cup,
15 which, in turn is carried by a mandrel . The inner
shell is inserted into the cup, and heat and
pressure is applied to the thermoplastic film to
fuse the film to the inner surface of the side wall
of the cup. The pressures for the inner shell against
20 the thermoplastic film ranges from shout 20 to about
80 pounds per square inch, preferably from about 30
to about 50 pounds per square inch (psi).
The fabrication rate for the film fusing
operation for a single machine producing 10-ounce
23 cups ranges from about 18 to 120 cups per minute.
Several machines can be used to increase the
production rate. Heat is applied to the
thermoplastic film by means of steam in order to
melt the thermoplastic film and the adjacent
30 polystyrene beads so that a cohesive effect occurs.
between the inner surface of the sidewall of the cup
and the thermoplastic film. The temperature and
time for this cohesion to occur may vary, for
example., from about 60°C to about 120ºC for about 13
35 to about 20 seconds.
15

9253 PCT
5 IC has been found that the thermoplastic film
also increases the rim strength of the container,
which, in effect, increases the overall strength of
the container. The rim strength is a measure of the
force required (in kilograms) to cause the rim to
10 crumble a one-fourth inch displacement from the
opened edge of the container.
Other embodiments of the invention involve the
thermoplastic- film being fused to the inxier and/or
outer surfaces of the sidewall and/or fused to the
16 inner and/or outer surfaces of the base of the
container.
The invention is further illustrated, but not
limited by, the following examples wherein all parts
and percentages are by weight unless otherwise
20 specified.
Examples
Example 1
This example illustrates the preparation of
25 thermoplastic film lined containers. The NOVA
Chemicals F2T1TU (expandable polystyrene) cup beads
blended with zinc stearate were pre-expanded in an
11-gallon Rodman Steam pre-expandar (Artisan
Industries Inc-l at atmospheric pressure. The pre-
30 expansion was operated batch wise. The weight of the
cup beads (i.e. 3.5 lbs.) was adjusted to make a
pre-puff with a density ranging between 2,6 - 3.6
pounds per cubic foot (pcf) . The newly prepared pre-
puff was air dried for 5 minutes to remove the
35 moisture and was allowed to age for about 4 hours
before molding.
16

9253 PCT
5 Six-ounce standard cups using different density
aged pre-puff besds were molded. The steam header
pressure used was 80 pounds per square inch (psi)
and the total cycle time was in the range of 7.50 to
8.25 seconds. The molded cups were allowed to age
10 overnight.
Pre-cut extruded polystyrene film (1.0 mil
thickl wade from NOVA. Chemical PS 2110 (general
solid polystyrene) resin was fused onto the inner
surface of the sidewall of the cups in the same
15 molder used for forming the cups. The header steam
pressure used in the film fusion process was 45
pounder per square inch and the total cycle time was
5.55 seconds. The film-lined containers were stored
overnight before testing.
20 The cups with the varying density pre-puff
beads, i.e. 3.47, 3.54 , 3.21, and 2.61 pcf, were
tested by tha following method: Spicy oil at room
temperature was poured into each container up to
around 80% of the cup's height. The outside wall of
25 each container containing the spicy oil was observed
for oil stains and leakage every 10 minutes over the
first l.5 hours., every 20 minutes in the time period
from 1.5 hours to 6 hours, and, then, every hour up
to a total of 48 hours.
30 The average time failure (ATF) for each cup
group sampling was calculated by adding the time to
failure for each container, and dividing the total
time by the number of containers tested. Typically,
ten cups of each group sampling were tested. The
35 maximum ATP value of 48 hours represents that none
of the cups for each cup group sampling exhibited
17

9253 PCT
5 any stain or leakage. The minimum ATP value of 0.17
hours represents that all of the cups in. each of cup
group sampling failed within the first 10 minutes.
Each cup in each group sampling was tested for
rim strength with and without a thermoplastic film
10 and the average force was recorded. Ten cups were
tested in each group sampling.
The results for the oil retention and the rim.
strength are shown in Table l, As indicated in Table
1, the cup samples with the thermoplastic film of
15 the invention have an increased ATF and rim strength
compared to the cup sample without the thermoplastic
film.

20) Example 2
The oil retention testing and the rim strength
testing cor cups with a pre-puff density of 3.4 7 pcf
were performed in a manner similar to that of
Example 1. These results are shown in Table 2. The
25 polystyrene film was similar to that used in Example
l and its thickness varied as shown in Table 2 . As
indicated in Table 2, the cup samples with the
thermoplastic film of the invention have an
18

5 increased ATF and rim strength compared to the cup
samples without the thermoplastic film.

Example 3
10 The oil retention testing and the rim strength
testing for cups with a pre-puff density of 3.50 pcf
were performed in a manner similar to that of
Example 1. The thermoplastic film was similar to
that used in Example 1 and was either extruded or
15 blown as indicated in Table 3 . The volume of the-
EPS cups was changed from 6 ounces to 16 ounces. The:
results are shown in Table 3 . The samples with the
thermoplastic film fabricated via an extrusion or a
blown process have comparable testing results,
20 Also, the samples with the thermoplastic film of the
invention regardless of the process for making the
thermoplastic film have an increased ATF and rim
strength compared to the samples without the
thermoplastic film.

19

9253 PCT

Example 4
In this Example, the polystyrene resin film was
replaced with the thermoplastic materials indicated
10 chersin. NOVA PS 3500, 4211, 5500, and 5102 are the
medium and high impact polystyrenes, all of which
are discussed hereinabove. As is indicated in Table
4, the cup samples, with the thermoplastic film
fabricated from the different thermoplastic
15 materials have comparable ATF and rim strength
values.

The cups with the fused thermoplastic film of
20 the above Examples have a generally uniform "rough"
pr "bumpy" inner sidewall surface. This is due in
part to the fact that the film material when fused
against the sidewall of the cup covers the voids
formed by the expanded polystyrene beads during the
25 mold processing of the cups and the applied
temperature for this "fusing" process causes the
expanded polystyrene beads to expand even further.
20

9253 PCT
5 The thermoplastic container is used' for
retaining pre-packaged foods, e.g. instant noodles,
soups, stews, chicken that are sold an the shelves
in the grocery stores. The container can be placed
in the freezer, or in the microwave for reheating
10 purposes without lessening the integrity of the
container.
While the present invention has been set forth
in terms of specific embodiments thereof, it will be
understood in view of the instant disclosure that
15 numerous variations upon the invention are now
enabled yet reside within the scope of the
invention. Accordingly, the invention is to be
broadly construed and limited only by the scope and
spirit of the claims now appended hereto.
20
21

9253 PCT
5 WHAT IS CLAIMED IS:
1. A container for retaining liquid and/or food
that contains oil and/or fatty components,
comprising:
a foam molded thermoplastic container having a
10 sidewall with an inner surface and an outer surface
and a base with an inner surface and an outer
surface; and
a thermoplastic film fused to at least one of
said, inner surface or said outer surface of said
15 sidewall of said foam molded thermoplastic container
for making said container resistant to the
penetration of said, liquid and/or said oil and/or
fat components of said food through said sidewall of
said container.
20 2. A container of claim 1 wherein said foam molded
thermoplastic container is made from expandable
thermoplastic- particles.
3. A container of claim 2 wherein said expandable
thermoplastic particles are expandable polystyrene
25 particles.
4. A container of claim 1 wherein said
thermoplastic film is made of a polymer selected
form the group consisting of solid polystyrene,
rubber modified polystyrene, polymethyl
30 methacrylate, polypropylene, polyethylene,
polyethylene terephthalate (PET), and mixtures
thereof.
3. A container of claim 4 wherein said
thermoplastic film is made of a polymer selected
35 from the group consisting of solid polystyrene and
rubber modified polystyrene.
22

9253 PCT
5 6. A container of claim 5 wherein said
thermoplastic film is made of solid polystyrene.
7. A container of claim l wherein said
thermoplastic film has a thickness ranging from
about 0.10 mil to about 5.0 mils.
10 B. A container of claim 1 wherein said
thermoplastic film is fused to said inner surface of
said sidewall of said container.
9. A container of claim 1 wherein said-
thermoplastic film is fused to said outer surface of
13 said sidewall of said container.
10. A container of claim 1 wherein said
thermoplastic film is fused, to said base of said.
container.
11 . A container of claim 1 wherein said
20 thermoplastic film is produced through an extrusion
process.
12. A container of claim l wherein said
thermoplastic film is produced through a blowing
process.
25 13. A method for forming a container for holding
liquid and/or foods containing oil and/or fatty
components, the steps comprising:
forming a foam thermoplastic container having
a sidewall witn an inner surface and an outer
30 surface and a base with an inner surface and an
outer surface, and.
fusing a thermoplastic film made of
thermoplastic resin to at least one of said inner
surface and said outer surface of said sidewall of
33 said container to make said container resistant to
the penetration of said liquid and/or said oil
23

9253 PCT
5 and/or fat components of said food through said
sidewall of said container
14. A method of claim 13 wherein said fusing
comprises the application of heat at a temperature
ranging from about 60ºC to about 12O°C for about 5
10 to about 20 seconds and the application of pressure
to said thermoplastic film ranging from about 20 to
about 80 pounds per square inch (psi).
15. A method of claim 13 wherein and foam
thermoplastic container is fabricated via a
15 container machine, the steps further comprising;
fusing said thermoplastic film to said one of
said inner surface and said outer surface of said
sidewall of said container via the same machine
used for fabricating said thermoplastic container.
20 16. A method of claim 13 the steps further
comprising.
fusing a thermoplastic film roads of
thermoplastic resin to said inner surface of said
sidewall of said container.
25 17. A method of claim 13 the steps further
comprising:
fusing a thermoplastic film made of
thermoplastic resin to said outer surface of said
sidewall of said container.
30 18, A methcd of claim 13 the steps further
comprising;
fusing a thermoplastic film made of
thermoplastic resin to said base of said container.

A foam thermoplastic cotitainer e.g. cup, bowl
10 molded from expandable thermoplastic particles e.g.
expandable polystyrene, has a film made of a
thermoplastic resin e.g, solid polystyrene, rubber-
modified polystyrene, PET, polyethylene,
polypropylene, fused to its inner sidewall surface
f5 by heat and pressure to create a barrier to resist
the leakage of liquid and food with oil and/or fatry
components and to increase the rim atrength of the
container. The thermoplastic resin film can be fused
to the outer surface of the container for printing
20 purposes and/or to create a barrier and/or can be
fused to the base surfaces of the container. The
molding machine used to form the foam container is
used to fuse the film to the container.

Documents:

« Previous Patent

Next Patent »

Patent Number

219503

Indian Patent Application Number

01187/KOLNP/2005

PG Journal Number

19/2008

Publication Date

09-May-2008

Grant Date

07-May-2008

Date of Filing

20-Jun-2005

Name of Patentee

NOVA CHEMICALS INC.

Applicant Address

WESTPOINTE CENTER, 1550 CORAOPOLIS HEIGHTS ROAD, MOON TOWNSHIP, PA 15108, U.S.A

Inventors:

#	Inventor's Name	Inventor's Address
1	TANG, JIANSHENG	3005 SALISBURY COURT, MARS, PA 16064, U.S.A
2	RUSSELL, JEFFORY, E.	207 PILGRIM DRIVE, SEWICKLEY, PA 15143, U.S.A
3	COWAN, DAVID, ALLEN	148 ABERDEEN DRIVE, CRANBERRY TOWNSHIP, PA 16066,U.S.A
4	WILLIAMS , MICHAEL , T.	112 PINEBROOK DRIVE, BEAVER FALLS, PA 15010, U.S.A
5	PILSPANEN, DENNIS, H	94 BRIM DRIVE, BEAVER, PA 15009, U.S.A
6	KWOK, JOHN, C.	1301 SARA COURT, MOON TOWNSHIP, PA 15108, U.S.A

PCT International Classification Number

B29D 22/00

PCT International Application Number

PCT/US03/040313

PCT International Filing date

2003-12-16

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10/325,062	2002-12-20	U.S.A.