US 3762454 A
A disposable garbage container is provided which will degrade in situ in a garbage dump. The container is made of a plastic film, e.g., a polyvinyl alcohol plastic film which will dissolve in the presence of moisture at temperatures of at least about 100 DEG F. One embodiment of the invention includes a degradable garbage container made of a plastic sheet material which comprises a laminate or a mixture of cold water soluble polyvinyl alcohol and hot water soluble polyvinyl alcohol.
Description (OCR text may contain errors)
United States Patent [1 1 Wilkins, Jr.
[ Oct. 2, 1973 1 1 DISPOSABLE GARBAGE CONTAINER  Inventor: Roy A. Wilkins, Jr., 806 Red Oak Ln., Arlington, Tex.
22 Filed: Nv.l5, 1971 211 Appl.No.: 198,575
 US. Cl. ..150/1,117/16,l17/138.8 PV, l61/D1G. 5, 161/410, 161/162, 161/166, 161/168, 161/7, 220/D1G. 30, 229/35 R  Int. Cl 1165f 1/14, 8326 /16 I58] Field of Search 61/5366;
l61/D1(j.5,4l0,162,168,166;150/1; 220/D1G. 229/ R; 117/16, 138.8 PV
156] References Cited UNlTED STATES PATENTS 2,413,789 1/1947 Scheiderbaver 260/913 VA 2,980,941 4/1961 Miller l6l/D1G. 5 3,089,493 5/1963 Galindo 161/410 Wilson 3,249,950 5/1966 161/410 3,279,511 10/1966 Griffin, Jr. 161/410 3,347,297 10/1967 Garland 220/D1G. 30 3,563,244 2/1971 Asaka 161/410 3,565,753 2/1971 Yurkowitz l61/D1G. 5
3,632,039 l/l972 Gayle /1 3,640,629 2/1972 161/410 3,652,371 3/1972 Hirata H 161/410 3,396,546 8/1968 Pleuger 61/5366 OTHER PUBLlCATlONS Davidson & Sittig, Water Soluble Resins, 2nd Ed. Reinhold Book Corp., N.Y., 1968, pp. 109-115, & 123. (Article by Argana et al.).
Primary lixamim'rGeorge F. Lesmes Assistant Examincr-Charles E. Lipsey Alt0rneyD. Carl Richards et a1.
15 Claims, 5 Drawing Figures DISPOSABLE GARBAGE CONTAINER This invention relates to disposable containers. In another aspect, this invention relates to a disposable garbage container which will degrade in the presence of water and increased temperature.
The increases in population and industry in metropolitan areas have resulted in corresponding increases in environmental pollution. A particularly troublesome problem which most cities in the world are facing is the adequate disposal of solid waste material such as household garbage. Most areas are still trying to solve the problem of what to do with mounting piles of solid waste materials which have been allowed to 'stagnate over the years. In addition to this, is the problem of the proper disposal of currently generated solid waste materials from homes, offices, and factories.
It is estimated that more than 90 percent of all collected solid waste material ends up in open dump and landfill disposal sites.
Cities have been perplexed with the problems of both collecting and disposing of this solid garbage. The practice of directly depositing garbage into conventional trash cans has resulted in unsanitary and littered areas, as well as much difficulty in garbage collection. As a result, many cities have instigated ordinances requiring each patron of the garbage system to enclose solid waste and household garbage materials within plastic garbage bags. These garbage bags are then collected and transferred to the disposal areas.
While this legislation has resulted in more sanitary conditions during garbage pickup and delivery to the disposal area, it has created problems because the plastic garbage bags add to the mounting piles of nondecomposable garbage rubble and hasten the occupation of the available landfill areas. In addition, other problems have been caused by the use of plastic garbage bags. For example, landfills containing numerous enclosed polyethylene bags containing household garbage and the like, have actually exploded due to the buildup of gas pressure caused by the natural decomposition of the garbage within the polyethylene bags.
Thus, while the use of the plastic garbage bag has imparted many beneficial factors in the garbage disposal system, it has also created many problems which contribute to our environmental pollution problems.
Therefore, one object of this invention is to provide a novel garbage container.
Another object of this invention is to provide a novel garbage container which will degrade in situ in a garbage dump and leave no polluting residue.
A further object of this invention is to provide novel disposable garbage containers which will degrade in situ in water disposal areas and in landfill disposal areas to yield no polluting residue.
According to one embodiment of this invention, a novel garbage container is provided which comprises a receptacle having a closable inlet, and is made of a thin plastic sheet material which is water soluble at temperatures of at least about lF. The preferred plastic material is a polyvinyl alcohol which is at least 98 percent hydrolyzed.
According to another embodiment of this invention, a novel garbage container is provided which comprises a receptacle with a closable inlet, and is made of thin plastic sheet material which comprises either a mixture or a laminate of a cold water soluble polyvinyl alcohol and a hot water soluble polyvinyl alcohol.
According to still another embodiment of this invention, the sidewalls of disposable garbage container of this invention carry microcapsules of liquid. The microcapsules contain liquid such as water, perfume, disinfectants, aqueous solutions of bacteria which will degrade the polymer film, and the like. Rupturing of the microcapsules results in sufficient moisture and/or bacteria to degrade the container, or the release of other desirable material such as perfume.
This invention can be more easily understood from a study of the drawings in which:
FIG. 1 is a perspective view of a preferred garbage container of the subject invention;
FIG. 2 is a schematic view showing the garbage container of the subject invention degrading in situ in a landfill;
FIG. 3 is a partial sectional view of a sidewall of a garbage container of the subject invention having a laminated structure;
FIG. 4 is a partial sectionalview of the sidewall of a garbage container of the subject invention having fiber reinforcement; and
FIG. 5 is a partial sectional view of a sidewall of a garbage container of the subject invention which carries microcapsules of liquid thereon.
Now referring to the drawings and in particular to FIG. 1, a preferred form of the disposable garbage container of the subject invention is illustrated in perspective. As shown, container 10 comprises a plastic tube infolded at areas 12, and sealed along bottom 14 thereof to yield a receptacle having a closable inlet 16.
Container 10 is formed of a plastic sheet material which is soluble in water at a temperature of at least about [00F, and preferably is soluble at a temperature within the range of from about F to about F. The preferred sheet material used in container 10 is a polyvinyl alcohol. It is to be noted that other polymeric materials which are soluble in water at a temperature of at least about 100F can be used as construction material for container 10. However, this embodiment will be described in relation to the preferred container 10 used in the scope of this invention which is made of polyvinyl alcohol sheet material.
The polyvinyl alcohol sheet material used in this embodiment is a conventional polyvinyl alcohol which is derived from the process of hydrolyzing at least about 98 mole percent of the acetate groups of polyvinyl acetate. Thus, as used in the scope of this invention the terms percent hydrolysis or percent hydrolyzed shall mean the mole percent of the acetate groups of polyvinyl acetates which have been hydrolyzed and thereby replaced by hydroxyl groups. Therefore, a 98 percent hydrolyzed polyvinyl alcohol is understood to mean polyvinyl acetate which has been hydrolyzed to the extent that 98 mole percent of the acetate groups have been replaced by hydroxyl groups.
The molecular weight of the polyvinyl alcohol to be used in the scope of this invention need only be sufficient to yield a polymer which is formable into a thin plastic film of at least about 1 mil and generally from I to 3 mils in thickness. Generally, it is preferred that the polyvinyl alcohol which is used in the scope of this invention have a viscosity of at least about 25 centipoises when measured in a 4 percent aqueous solution of the polymer at 20C by any conventional technique such as the Hoeppler falling ball method or other techniques, such as with a Brookfield viscometer, LVF (No.
l spindle 60 rpm 20C). Generally, any polyvinyl alcohol which is hydrolyzed from about 98-l00 percent and has a viscosity of from about 25 to about 135 centipoises measured in a 4 percent aqueous solution at 20C can be utilized in the scope of this embodiment of the subject invention. Such material will hereinafter be referred to as hot water soluble polyvinyl alcohol.
It is genrally preferred that container 10 have a wall thickness of from about 1 to 3 mils. The resulting container is relatively high tensile strength and tearresistance, and is insoluble in cold water.
The polyvinyl alcohol film can be formed into a suitable tube in the manufacture of container 10 by conventional methods such as extrusion. Thus, container 10 can be manufactured by longitudinally infolding opposed regions of an extruded tube, sequentially severing the infolded tube to obtain a number of tube segments, and heat sealing one open end of each tube segment. Alternately, a suitable container can be formed by folding a sheet of polyvinyl alcohol in half and sealing such as by heat sealing edges of the open side and one end of the resulting folded material to yield a container comprising a receptacle with a closable end. Any other suitably shaped container configuration can be used in the scope of this invention. Other methods of forming the polyvinyl alcohol film can be utilized as desired, such as by casting the film from water solutions of the polyvinyl alcohol.
It is to be understood that minor quantities of materials such as plasticizers, deodorants, colorants, and the like can be present in the polyvinyl alcohol film. Examples of suitable plasticizers include high boiling water soluble organic compounds containing hydroxyl, amide, or amino groups; glycerine; ethylene; glycol; low molecular weight polyoxyethylene glycol; sorbitol; formamide; and urea. Suitable colorants include conventional pigments and dyes. Filler materials such as clay and calcium carbonate and the like can also be present in the film. A suitable bactericide includes hexachlorophene. Other such conventional materials can be utilized in minor quantities in the polyvinyl alcohol film. In addition, for heavy duty operations, the polyvinyl alcohol film can contain reinforcing fibers, preferably cellulose fibers or polyvinyl acetate fibers.
The fibers can be randomly dispersed within the polyvinyl alcohol film, or can comprise a knitted network which is encapsulated with polyvinyl alcohol.
Examples of suitable commercially available polyvinyl alcohols which can be used to form the plastic sheet material for container 10 of the subject invention include the polyvinyl alcohols manufactured by Du Pont de Nemours and sold under the trademark of EL- VANOL." Specific suitable ELVANOL materials include ELVANOL 72-60, and ELVANOL 71-30. Other suitable commercially available polyvinyl alcohols which can be used to form container 10 of the subject invention are manufactured by Air Reduction Chemical & Carbide Company of New York, N.Y. and sold under the trademark of VINOL." Specific compounds include VINOL 125 and VINOL 165. Examples of other suitable commercially available hot water soluble materials (soluble at a temperature of at least about IF) which can be used in the scope of this invention as the construction material for container include the polyethylene oxides sold under the trademark of WSR N-80 and WSR N-l0 by Union Carbide.
In use, container 10 is filled with disposable solid material, for example, household garbage, and then inlet 16 is closed by suitable means such as tie wire 18 (FIG. 2). The enclosed container can then be deposited within an earthen excavation at an appropriate garbage dump area and covered with earth in the conventional manner. Preferably, before the garbage is covered, the bags of the subject'invention are lightly sprayed with water. The temperature of the decomposing garbage within enclosed container 10 in such a landfill will heat container 10 to a temperature well above 100F. This increased temperature together with moisture within the landfill as well as the moisture generated on the interior of the bag, which condenses on the inside wall thereof due to the decomposition of the garbage material, will dissolve portions 20 of the sidewalls of container 10, as illustrated in FIG. 2. This degradation of portions 20 of the sidewalls of container 10 will cause the decomposing garbage to flow normally from container I0 and will allow gases formed in the decomposition of the garbage to be released from container 10 and slowly diffuse into the soil. The dissolved polyvinyl alcohol will remain in aqueous solution, and the resulting aqueous solution is nondeleterious to the environment. In addition, the resulting polyvinyl alcohol is bio degradable by common bacteria in garbage fill. Tests show that such polyvinyl alcohol has a very low biochemical oxygen demand during decomposition. Container 10 will finally become totally degraded in the garbage fill and will thereby not contribute to the residual indestructible solid waste material which is ever present in garbage landfill areas.
According to another embodiment of the subject invention, a degradable garbage container is provided which is suitable for sea disposal in that portions of the bag will degrade in relatively cold water to release the contents of the bag in the disposal area. As is well known, many cities around seaport areas dispose of solid waste material in ocean dumping grounds. The use of conventional plastic garbage bags in these areas for containing solid waste material such as household garbage, is undesirable because such bags have a tendency to float due to entrapped air. In addition, the plastic material is nondegradable by the seawater and constitutes an added source of ocean pollution. In ac cordance with this embodiment of the subject invention, a plastic garbage container which can have a similar configuration to that of container 10 is made from a plastic film material which is composed of a mixture of cold water soluble polymeric material and a noncold water soluble polymeric material. Examples of suitable cold water soluble polymeric materials which can be used in the scope of this invention include methyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, and the like. Examples of suitable non-cold water soluble polymeric materials which can be used in the scope of this invention include the above-described hot water soluble polyvinyl alcohols" and polyethylene oxides.
The preferred cold water soluble polymeric materials are polyvinyl alcohols which are less than 98 percent hydrolyzed and will completely dissolve in water at temperatures less than about 100F, e.g., about F. Preferably, the cold water soluble polyvinyl alcohol for use in this embodiment is from 87 to about 89 percent hydrolyzed; however, polyvinyl alcohols with both lower and higher degrees of hydrolysis can be utilized.
Generally the cold water soluble polyvinyl alcohol is at least about 70 percent hydrolyzed. Commercially available polyvinyl alcohols which can be used in the scope of this embodiment include the material sold by Du Pont under the trademark ELVANOL 50-42; and EL- VANOL 52-22.
It is only necessary that the cold water soluble polymeric material have a molecular weight sufficient to enable it to be molded by suitable techniques such as extrusion, to form a thin plastic film having a uniform thickness of between about 1 to about 3 mils. It is preferred that the cold water soluble polymeric material have a viscosity of at least about 25 centipoises, as measured in a 4 percent aqueous solution of the polymer at 20C by any conventional method as hereinbefore described.
The preferred method of producing a sea disposable garbage container of the subject invention includes initially forming a blend of cold and hot water soluble polyvinyl alcohols and thereafter forming a plastic sheet material which is then formed into suitable garbage containers. Specifically, the polymer blend can be produced by admixing from about 5 to about 65 parts by weight of the cold water soluble polyvinyl alcohol with from about 95 to about 35 parts by weight of the hot water soluble polyvinyl alcohol. More preferably, the blend is produced by admixing from about to about 50 parts by weight of the cold water soluble polyvinyl alcohol with from about 90 to about 50 parts by weight of the hot water soluble polyvinyl alcohol. The cold and hot water polyvinyl alcohols can be admixed in powdered form and blended thoroughly and thereafter melted and extruded in conventional machinery.
The resulting container formed from the blend of cold and hot water soluble polyvinyl alcohols possess sufficient structural integrity and moisture-resistance to withstand normal household handling, and handling during garbage pickup and delivery to a sea disposal barge, for example. However, once the garbage container is deposited in the ocean, water will readily dissolve the cold water soluble polyvinyl alcohol, release the entrapped air from the bag and thoroughly engulf the enclosed garbage to thereby allow natural decomposition thereof. It is to be understood that any other polymeric material which is compatible with the cold water soluble polyvinyl alcohol can be used in place of the hot water soluble polyvinyl alcohol in the scope of this embodiment, e.g., polyethylene oxide. However, because the hot water soluble polyvinyl alcohol is biodegradable and has a low biochemical oxygen demand, its use in this embodiment is highly preferred.
As an alternate to a container material which comprises a blend of the cold water soluble polyvinyl alcohol and the hot water soluble polyvinyl alcohol, suitable undersea degradable garbage bags can be produced from laminated structures, such as illustrated in FIG. 3. FIG. 3 is a partial sectional view of a sidewall of a suitable laminated structure which can be utilized in accordance with this invention. As shown, the sidewalls 30 of the container comprise a layer 32 which is laminated by conventional techniques with layer 34. Layer 32 which serves as the substructure for sidewall 30 is made of the aforementioned non-cold water soluble polymeric material and preferably a hot water soluble polyvinyl alcohol. Layer 34 comprises a cold water soluble polymeric material, e.g., the aforementioned cold water soluble polyvinyl alcohol material. Furthermore, layer 32 carries a series of apertures 36 therethrough. The two films 32 and 34 can be produced by any conventional film forming technique, and apertures 36 can be made through film 34 either during the forming technique or afterwards in a hole-punching operation. The number and size and configuration of apertures 36 can be varied as desired. The two films are then laminated together by suitable heat sealing techniques to yield a composite laminate which generally comprises a double wall thickness material except in areas of apertures 36. A container made from the laminated material will maintain its structural integrity during normal handling operations and in the presence of minor amounts of moisture. However, when it is utilized in ocean or fresh water disposal, film 34 will dissolve in the ocean water and allow water to flow to the interior of the container via apertures 36. Thus, the container functions in the same manner as the container made with the above-described blend of cold water soluble polymer with a non-cold water soluble polymer.
Still a further embodiment of this invention is illustrated in FIG. 4. As shown, FIG. 4 is a partial sectional view of a portion of the sidewall of a suitable container which can be used in the scope of this invention, and is particularly useful for undersea disposal. Sidewall 40 comprises a woven fiber innerlayer 42 which serves as a substructure for sidewall 40 and is encapsulated by plastic layer 44. Layer 42 can comprise any knitted or woven reinforcing fibrous material, but preferably a fibrous material which is made from the aforementioned hot water soluble polyvinyl alcohol which is a biodegradable material. Fiber layer 42 is encapsulated by layer 44 of the aforementioned cold water soluble polymeric material and preferably polyvinyl alcohol. A garbage container made of this material will function'in undersea disposal in a similar manner as a container made of the material illustrated in FIG. 3.
According to still another embodiment of this invention, either the hot water soluble degradable garbage container of the invention which is used in standard landfills or the underwater disposable garbage container can carry suitable amounts of microencapsulated liquid. For example, as shown in FIG. 5, microcapsules 50 containing liquid (microspheres) can be affixed to the surface of container 10 by suitable techniques. One particularly suitable technique for affixing the microencapsulated liquid to the surface of container 10 involves the use of an annular nozzle or a ring of nozzles positioned in alignment with an extruder die for a tube such that the extruded tube passes therethrough. A gaseous stream such as air or nitrogen carrying conventional microspheres containing a suitable liquid is emitted from the nozzle means and directed inwardly to impinge upon the extruded tube passing from the extruder die. The impingement of the gaseous stream containing the entrained microspheres upon the soft extruded tube implants the microspheres in the soft sidewalls, and thereafter hardens the sidewalls. The entire sidewall portion or preferably the lower or middle sidewall portion of container 10 can be coated with microencapsulated liquid such as water, for example. If desired, only the upper sidewall portion for example, about the upper 10 to 30 percent of the container adjacent opening 11 can be treated with suitable microspheres containing a microencapsulated liquid such as a deodorant or disinfectant. When using a container made by this process, the act of affixing tie wire 18 to the upper portion of container 10 will burst the microspheres and release the liquid. When container 10 carries microspheres containing water, heating or special treating of the container during the garbage disposal will burst the microspheres and moisten the polyvinyl alcohol to hasten the degradation thereof. In addition, if desirable, minor amounts of bacteria which will degrade the poly mer film can be included within the microencapsulated liquid. For example, conventional bacteria normally found in a garbage disposal area can be used in microspheres affixed to container 10 made of polyvinyl alcohol.
Alternately, if desired, the microencapsulated liquid can be molded within the body of the film which forms container 10 by admixing the microspheres with the polyvinyl alcohol before the film is made. The microspheres containing liquid can be produced by any conventional technique and can be made from any suitable encapsulating material such as glass, epoxy resins, phenolic resins, waxes, or polyvinyl alcohol. The conventionally produced microspheres generally have diameters in the range of from about 5 to 5,000 microns and are preferably from about 20 to 150 microns in diameter. These microspheres are conventionally utilized in the manufacture of carbonless paper and sample paper containing various microencapsulated odors. The microspheres can be ruptured by any suitable method, depending upon the composition of the encapsulating material. Suitable techniques include heat, pressure, or techniques such as subjecting the container to high frequency radio waves or ultraviolet or infrared radiation.
While this invention has been described in relation to its preferred embodiments, it is to be understood that various modifications thereof will now be apparent to one skilled in the art upon reading this specification and it is intended to cover such modifications which fall within the scope of the appended claims.
1. A flexible garbage container comprising a receptacle having a closable inlet, said receptacle made of film which comprises hot water soluble film, and having microencapsulated liquid container within rupturable microspheres maintained in a fixed contact with said film, said microencapsulated liquid consisting essentially of water or an aqueous solution of bacteria which will degrade the polymer film and being in contact with said film in sufficient quantities to dissolve said film in contact with said microspheres when said microspheres are ruptured and said container is heated to a temperature sufficient to solubilize said film.
2. The flexible garbage container of claim 1 wherein said microspheres are dispersed within said film.
3. The flexible garbage container of claim 1 wherein said microspheres are implanted on the surface of said film.
4. The flexible garbage container of claim 1 comprising a tubular member having opposed sidewalls and sealed at one end and having said closable inlet at the opposite end thereof.
5. The flexible garbage container of claim 4 wherein said sidewalls are coated with said microspheres.
6. The flexible garbage container of claim 4 wherein the middle sidewall portions of said container are coated with microspheres.
7. The flexible garbage container of claim 4 wherein the lower sidewall portions of said container are coated with said microspheres.
8. A flexible garbage container comprising a receptacle having a closable inlet, said receptacle made of a hot water soluble polymer film which is water soluble at temperatures of at least about F, and having microencapsulated liquid contained within rupturable microspheres maintained in fixed contact with said film, said microencapsulated liquid consisting essentially of water or an aqueous solution of bacteria which will degrade the polymer film and being in contact with said film in sufficient quantities to dissolve said film in contact with said microspheres when said microspheres are ruptured and said container is heated to at least about 100F.
9. The flexible garbage container of claim 8 wherein said hot water soluble film is polyvinyl alcohol which is at least 98 percent hydrolyzed.
10. The flexible garbage container of claim 8 wherein said microspheres are dispersed within said film.
1 l. The flexible garbage container of claim 8 wherein said microspheres are implanted on the surface of said film.
12. The flexible garbage container of claim 8 comprising a tubular member having opposed sidewalls and sealed at one end and having said closable inlet at the opposite end thereof.
13. The flexible garbage container of claim 12 wherein said sidewalls are coated with said microspheres.
14. The flexible garbage container of claim 12 wherein the middle sidewall portions of said container are coated with said microspheres.
15. The flexible garbage container of claim 12 wherein the lower sidewall portions of said container are coated with said microspheres.
223 UNITED STATES PATENT W?! CERTIFKCATE OFCORR Dated' Oats-be: 2, 1973 I Inventofls; Roy A. Wilkins, Jr.
It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as} shown bekcwz Col. 7, line 43 "container" should be -T'contained" Signed and sealed this 9th day of April 1971p (SEAL) Attest:
EDWARD I LFLETGIEHJR. G MARSHALL DAMN Attosting Officer- Comivs'aioner Qf Patents